Wmc diversity
description
Transcript of Wmc diversity
Diversity techniques for mobile wireless radio systems
Diversity Dictionary
ldquothe presence of a wide range of variation Including everyonerdquo
AJALAJ Assistant Professor ndashDept of ECE
Federal Institute of Science And Technology (FISAT) TM MAIL ec2reachgmailcom
Cultural Dimensions
PERSONAL
CORPORATE
ETHNIC
GENERATIONAL
RELIGIOUS
CLASS
GENDER
REGIONAL
NATIONAL
PROFESSIONAL EDUCATIONAL
UNITY IN DIVERSITY
What is Diversity
bull Diversity may refer to Multiculturalism the ideology of including people of diverse
cultural and religious backgrounds Diversity (politics) the political and social policy of
encouraging tolerance for people of different backgrounds Diversity (business) the business tactic which encourages
diversity to better serve a heterogeneous customer base Diversity training the process of educating employees
students or volunteers to function in a diverse environment Biodiversity the variation of life forms within a given
ecosystem Diversity scheme a method for improving the reliability of a
message signal by using multiple communications channels
DIVERSITY as far as mobile
wireless radio systems are
concerned
Common assumption
bull Common assumption
signals that scatter off of different objects fade independently
How when diversity is created
bull Diversity is created when these signals are separated in the receiver
Examples
RAKE receiver - - separates paths by delay [PATH DIVERSITY]
Multi beam antenna - - separates paths by angle [ANGLE DIVERSITY]
change the relative phases of the multi pathsignals
bull Examplesbull 1048672Identical antennas slightly different locations[SPACE DIVERSITY]bull 1048672Same signal received on different RF carriers[FREQUENCY DIVERSITY] Required carrier
separation depends inversely on delay spread
Another way to create diversity
Still other ways to generate diversity
bull Dual polarized antennas [POLARIZATION DIVERSITY]
Introduction
bull Fading
Signal fluctuations caused by multipath propagation and shadowing effects
bull Diversity
Receiving the same information bearing signal over 2 or more fading channels
Introduction (contrsquod)
bull SpaceTransmission using multiple transmitreceive antennas
bull FrequencyTransmission using multiple frequency channels separated by at least the coherence bandwidth
bull Time Transmission using multiple time slots separated by at least the coherence time
Spatial diversity
bull Single-input single-output (SISO) channel
No spatial diversitybull Single-input multiple-output (SIMO) channel
Receive diversitybull Multiple-input single-output (MISO) channel
Transmit diversity bull Multiple-input multiple-output (MIMO) channel
Combined transmit and receive diversity
The following classes of diversity schemes can be identified
1Space diversity 2Polarization diversity 3Frequency diversity 4Time diversity 5Angle or direction diversity
1] Space diversity
bull The signal is transferred over several different propagation paths
bull In the case of wired transmission this can be achieved by transmitting via multiple wires
bull In the case of wireless transmission it can be achieved by antenna diversity using multiple transmitter antennas (transmit diversity) andor multiple receiving antennas (reception diversity)
bull In the latter case a diversity combining technique is applied before further signal processing takes place
2] Polarization diversity
bull Polarization diversity Multiple versions of a signal are transmitted and received via antennas with different polarization
bull A diversity combining technique is applied on the receiver side
POLARIZER
3] Frequency diversity
bull Frequency diversity The signal is transferred using several frequency channels or spread over a wide spectrum that is affected by frequency-selective fading
bull Middle-late 20th century microwave radio relay lines often used several regular wideband radio channels and one protection channel for automatic use by any faded channel Later examples include OFDM modulation in combination with subcarrier interleaving and
forward error correction Spread spectrum for example frequency hopping or DS-CDMA
4] Time diversity
bull Time diversity Multiple versions of the same signal are transmitted at different time instants
Terrestrial microwave radio system with two antenna arrays configured for space-diversity
Diversity Combining
bull Once you have created two or morediversity channels what do you do with them
Spatial diversity (contrsquod)
bullMaximum ratio combining (MRC)
h1
h2
h1
h2
yx
Combining schemes
bullSelection combining (SC)
h1
h2
yx
MonitorSNR
Selectbranch
Switch-and-stay combining (SSC) Switch-and-examine combining (SEC)
h1
h2
x
ComparatorChannelestimator
switchingthreshold
bullSwitched diversity
No trade off to
Without excessively increasing
bull 1 transmitting powerbull 2 Co-channel reuse distance
bull One of the most effective technique to solve this issue is diversity reception technique
What are all the needs of diversity techniques
bull 1No of signal transmission pathsbull 2A circuit to combine the received signal or
select one of them
CONCEPTS OF DIVERSITY BRANCH AND SIGNAL PATH
(a) Branch Construction method using frequency diversity
(b) Branch Construction method using Time diversity
COMBINING AND SWITCHNING METHODS
COMBINING AND SWITCHNINGMETHODS
FOR COHERENT DETECTION
FOR NON - COHERENT DETECTION
FOR COHERENT DETECTION
bull There is no difference whether the combining is carried out in the pre detection or in the post detection stage
FOR NON-COHERENT DETECTION
bull There is a difference in performance exists between whether pre detection amp post detection combining methods
(a) Maximal ratio combining (MRC)
bull MRC is the best performance improvement compared with the other methods
bull However the trade off is It requires 1 cophasing 2 weighting 3summing circuitsResulting in most complicated implementationComplexity performance
(b) Equal Gain Combining (EGC)
EGCbull EGC is similar to MRC except the weighting
circuits are omittedbull The performance improvement obtained by
equal gain combiner is slightly inferior to that of a MRC since the interference and noise corrupted signal combined with high quality signals
For VHF UHF and microwave wireless radio applications
bull Both MRC and EGC methods are unsuitablebull Compared with MRC EGC methods the
selection method is more suitable for mobile radio applications because of its simple implementation
(c) Selection or Switching Combining
bull The diversity branch having the highest signal level (or) lowest Pe is selected
bull Also in addition stable operation is easily achieved even in the fast multipath fading environments
bull But the performance improvement obtained by the selection method is still only slightly inferior to that of MRC method
Disadvantage of Selection or Switching
bull Combining The continuous monitoring of the signals requires the same no of receivers as the no of diversity branches
bull This redundancy can be alleviated by the use of switching or scanning receiver
SWITCHNINGMETHODS
FIXED THERSHOLD VARIABLE THERSHOLD
(a) Switching Methods with Fixed threshold
bull The switching from one branch to the other occurs when the signal level falls below a threshold value
bull The threshold value is fixedbull However this threshold value is not
necessarily the best over the entire service area
FIXED THERSHOLD
(b) Switching Methods with Variable threshold
bull Here the threshold value is adjusted dynamically as the vehicle moves
bull It includes the feedback using Estimationbull But it may introduce the envelope and phase
transients that will reduce the performance improvement
VARIABLE THERSHOLD
Conclusions
bull The diversity is used to provide the receiver with several replicas of the same signal
bull Diversity techniques are used to improve the performance of the radio channel without any increase in the transmitted power
bull As higher as the received signal replicas are decorrelated as much as the diversity gain
Thank you for you attention
- No trade off to
- What are all the needs of diversity techniques
- CONCEPTS OF DIVERSITY BRANCH AND SIGNAL PATH
- (a) Branch Construction method using frequency diversity
- (b) Branch Construction method using Time diversity
- COMBINING AND SWITCHNING METHODS
- Slide 29
- FOR COHERENT DETECTION
- (a) Maximal ratio combining (MRC)
- Slide 32
- (b) Equal Gain Combining (EGC)
- EGC
- For VHF UHF and microwave wireless radio applications
- (c) Selection or Switching Combining
- Slide 37
- Disadvantage of Selection or Switching
- Slide 39
- (a) Switching Methods with Fixed threshold
- Slide 41
- (b) Switching Methods with Variable threshold
- Slide 43
-
Cultural Dimensions
PERSONAL
CORPORATE
ETHNIC
GENERATIONAL
RELIGIOUS
CLASS
GENDER
REGIONAL
NATIONAL
PROFESSIONAL EDUCATIONAL
UNITY IN DIVERSITY
What is Diversity
bull Diversity may refer to Multiculturalism the ideology of including people of diverse
cultural and religious backgrounds Diversity (politics) the political and social policy of
encouraging tolerance for people of different backgrounds Diversity (business) the business tactic which encourages
diversity to better serve a heterogeneous customer base Diversity training the process of educating employees
students or volunteers to function in a diverse environment Biodiversity the variation of life forms within a given
ecosystem Diversity scheme a method for improving the reliability of a
message signal by using multiple communications channels
DIVERSITY as far as mobile
wireless radio systems are
concerned
Common assumption
bull Common assumption
signals that scatter off of different objects fade independently
How when diversity is created
bull Diversity is created when these signals are separated in the receiver
Examples
RAKE receiver - - separates paths by delay [PATH DIVERSITY]
Multi beam antenna - - separates paths by angle [ANGLE DIVERSITY]
change the relative phases of the multi pathsignals
bull Examplesbull 1048672Identical antennas slightly different locations[SPACE DIVERSITY]bull 1048672Same signal received on different RF carriers[FREQUENCY DIVERSITY] Required carrier
separation depends inversely on delay spread
Another way to create diversity
Still other ways to generate diversity
bull Dual polarized antennas [POLARIZATION DIVERSITY]
Introduction
bull Fading
Signal fluctuations caused by multipath propagation and shadowing effects
bull Diversity
Receiving the same information bearing signal over 2 or more fading channels
Introduction (contrsquod)
bull SpaceTransmission using multiple transmitreceive antennas
bull FrequencyTransmission using multiple frequency channels separated by at least the coherence bandwidth
bull Time Transmission using multiple time slots separated by at least the coherence time
Spatial diversity
bull Single-input single-output (SISO) channel
No spatial diversitybull Single-input multiple-output (SIMO) channel
Receive diversitybull Multiple-input single-output (MISO) channel
Transmit diversity bull Multiple-input multiple-output (MIMO) channel
Combined transmit and receive diversity
The following classes of diversity schemes can be identified
1Space diversity 2Polarization diversity 3Frequency diversity 4Time diversity 5Angle or direction diversity
1] Space diversity
bull The signal is transferred over several different propagation paths
bull In the case of wired transmission this can be achieved by transmitting via multiple wires
bull In the case of wireless transmission it can be achieved by antenna diversity using multiple transmitter antennas (transmit diversity) andor multiple receiving antennas (reception diversity)
bull In the latter case a diversity combining technique is applied before further signal processing takes place
2] Polarization diversity
bull Polarization diversity Multiple versions of a signal are transmitted and received via antennas with different polarization
bull A diversity combining technique is applied on the receiver side
POLARIZER
3] Frequency diversity
bull Frequency diversity The signal is transferred using several frequency channels or spread over a wide spectrum that is affected by frequency-selective fading
bull Middle-late 20th century microwave radio relay lines often used several regular wideband radio channels and one protection channel for automatic use by any faded channel Later examples include OFDM modulation in combination with subcarrier interleaving and
forward error correction Spread spectrum for example frequency hopping or DS-CDMA
4] Time diversity
bull Time diversity Multiple versions of the same signal are transmitted at different time instants
Terrestrial microwave radio system with two antenna arrays configured for space-diversity
Diversity Combining
bull Once you have created two or morediversity channels what do you do with them
Spatial diversity (contrsquod)
bullMaximum ratio combining (MRC)
h1
h2
h1
h2
yx
Combining schemes
bullSelection combining (SC)
h1
h2
yx
MonitorSNR
Selectbranch
Switch-and-stay combining (SSC) Switch-and-examine combining (SEC)
h1
h2
x
ComparatorChannelestimator
switchingthreshold
bullSwitched diversity
No trade off to
Without excessively increasing
bull 1 transmitting powerbull 2 Co-channel reuse distance
bull One of the most effective technique to solve this issue is diversity reception technique
What are all the needs of diversity techniques
bull 1No of signal transmission pathsbull 2A circuit to combine the received signal or
select one of them
CONCEPTS OF DIVERSITY BRANCH AND SIGNAL PATH
(a) Branch Construction method using frequency diversity
(b) Branch Construction method using Time diversity
COMBINING AND SWITCHNING METHODS
COMBINING AND SWITCHNINGMETHODS
FOR COHERENT DETECTION
FOR NON - COHERENT DETECTION
FOR COHERENT DETECTION
bull There is no difference whether the combining is carried out in the pre detection or in the post detection stage
FOR NON-COHERENT DETECTION
bull There is a difference in performance exists between whether pre detection amp post detection combining methods
(a) Maximal ratio combining (MRC)
bull MRC is the best performance improvement compared with the other methods
bull However the trade off is It requires 1 cophasing 2 weighting 3summing circuitsResulting in most complicated implementationComplexity performance
(b) Equal Gain Combining (EGC)
EGCbull EGC is similar to MRC except the weighting
circuits are omittedbull The performance improvement obtained by
equal gain combiner is slightly inferior to that of a MRC since the interference and noise corrupted signal combined with high quality signals
For VHF UHF and microwave wireless radio applications
bull Both MRC and EGC methods are unsuitablebull Compared with MRC EGC methods the
selection method is more suitable for mobile radio applications because of its simple implementation
(c) Selection or Switching Combining
bull The diversity branch having the highest signal level (or) lowest Pe is selected
bull Also in addition stable operation is easily achieved even in the fast multipath fading environments
bull But the performance improvement obtained by the selection method is still only slightly inferior to that of MRC method
Disadvantage of Selection or Switching
bull Combining The continuous monitoring of the signals requires the same no of receivers as the no of diversity branches
bull This redundancy can be alleviated by the use of switching or scanning receiver
SWITCHNINGMETHODS
FIXED THERSHOLD VARIABLE THERSHOLD
(a) Switching Methods with Fixed threshold
bull The switching from one branch to the other occurs when the signal level falls below a threshold value
bull The threshold value is fixedbull However this threshold value is not
necessarily the best over the entire service area
FIXED THERSHOLD
(b) Switching Methods with Variable threshold
bull Here the threshold value is adjusted dynamically as the vehicle moves
bull It includes the feedback using Estimationbull But it may introduce the envelope and phase
transients that will reduce the performance improvement
VARIABLE THERSHOLD
Conclusions
bull The diversity is used to provide the receiver with several replicas of the same signal
bull Diversity techniques are used to improve the performance of the radio channel without any increase in the transmitted power
bull As higher as the received signal replicas are decorrelated as much as the diversity gain
Thank you for you attention
- No trade off to
- What are all the needs of diversity techniques
- CONCEPTS OF DIVERSITY BRANCH AND SIGNAL PATH
- (a) Branch Construction method using frequency diversity
- (b) Branch Construction method using Time diversity
- COMBINING AND SWITCHNING METHODS
- Slide 29
- FOR COHERENT DETECTION
- (a) Maximal ratio combining (MRC)
- Slide 32
- (b) Equal Gain Combining (EGC)
- EGC
- For VHF UHF and microwave wireless radio applications
- (c) Selection or Switching Combining
- Slide 37
- Disadvantage of Selection or Switching
- Slide 39
- (a) Switching Methods with Fixed threshold
- Slide 41
- (b) Switching Methods with Variable threshold
- Slide 43
-
What is Diversity
bull Diversity may refer to Multiculturalism the ideology of including people of diverse
cultural and religious backgrounds Diversity (politics) the political and social policy of
encouraging tolerance for people of different backgrounds Diversity (business) the business tactic which encourages
diversity to better serve a heterogeneous customer base Diversity training the process of educating employees
students or volunteers to function in a diverse environment Biodiversity the variation of life forms within a given
ecosystem Diversity scheme a method for improving the reliability of a
message signal by using multiple communications channels
DIVERSITY as far as mobile
wireless radio systems are
concerned
Common assumption
bull Common assumption
signals that scatter off of different objects fade independently
How when diversity is created
bull Diversity is created when these signals are separated in the receiver
Examples
RAKE receiver - - separates paths by delay [PATH DIVERSITY]
Multi beam antenna - - separates paths by angle [ANGLE DIVERSITY]
change the relative phases of the multi pathsignals
bull Examplesbull 1048672Identical antennas slightly different locations[SPACE DIVERSITY]bull 1048672Same signal received on different RF carriers[FREQUENCY DIVERSITY] Required carrier
separation depends inversely on delay spread
Another way to create diversity
Still other ways to generate diversity
bull Dual polarized antennas [POLARIZATION DIVERSITY]
Introduction
bull Fading
Signal fluctuations caused by multipath propagation and shadowing effects
bull Diversity
Receiving the same information bearing signal over 2 or more fading channels
Introduction (contrsquod)
bull SpaceTransmission using multiple transmitreceive antennas
bull FrequencyTransmission using multiple frequency channels separated by at least the coherence bandwidth
bull Time Transmission using multiple time slots separated by at least the coherence time
Spatial diversity
bull Single-input single-output (SISO) channel
No spatial diversitybull Single-input multiple-output (SIMO) channel
Receive diversitybull Multiple-input single-output (MISO) channel
Transmit diversity bull Multiple-input multiple-output (MIMO) channel
Combined transmit and receive diversity
The following classes of diversity schemes can be identified
1Space diversity 2Polarization diversity 3Frequency diversity 4Time diversity 5Angle or direction diversity
1] Space diversity
bull The signal is transferred over several different propagation paths
bull In the case of wired transmission this can be achieved by transmitting via multiple wires
bull In the case of wireless transmission it can be achieved by antenna diversity using multiple transmitter antennas (transmit diversity) andor multiple receiving antennas (reception diversity)
bull In the latter case a diversity combining technique is applied before further signal processing takes place
2] Polarization diversity
bull Polarization diversity Multiple versions of a signal are transmitted and received via antennas with different polarization
bull A diversity combining technique is applied on the receiver side
POLARIZER
3] Frequency diversity
bull Frequency diversity The signal is transferred using several frequency channels or spread over a wide spectrum that is affected by frequency-selective fading
bull Middle-late 20th century microwave radio relay lines often used several regular wideband radio channels and one protection channel for automatic use by any faded channel Later examples include OFDM modulation in combination with subcarrier interleaving and
forward error correction Spread spectrum for example frequency hopping or DS-CDMA
4] Time diversity
bull Time diversity Multiple versions of the same signal are transmitted at different time instants
Terrestrial microwave radio system with two antenna arrays configured for space-diversity
Diversity Combining
bull Once you have created two or morediversity channels what do you do with them
Spatial diversity (contrsquod)
bullMaximum ratio combining (MRC)
h1
h2
h1
h2
yx
Combining schemes
bullSelection combining (SC)
h1
h2
yx
MonitorSNR
Selectbranch
Switch-and-stay combining (SSC) Switch-and-examine combining (SEC)
h1
h2
x
ComparatorChannelestimator
switchingthreshold
bullSwitched diversity
No trade off to
Without excessively increasing
bull 1 transmitting powerbull 2 Co-channel reuse distance
bull One of the most effective technique to solve this issue is diversity reception technique
What are all the needs of diversity techniques
bull 1No of signal transmission pathsbull 2A circuit to combine the received signal or
select one of them
CONCEPTS OF DIVERSITY BRANCH AND SIGNAL PATH
(a) Branch Construction method using frequency diversity
(b) Branch Construction method using Time diversity
COMBINING AND SWITCHNING METHODS
COMBINING AND SWITCHNINGMETHODS
FOR COHERENT DETECTION
FOR NON - COHERENT DETECTION
FOR COHERENT DETECTION
bull There is no difference whether the combining is carried out in the pre detection or in the post detection stage
FOR NON-COHERENT DETECTION
bull There is a difference in performance exists between whether pre detection amp post detection combining methods
(a) Maximal ratio combining (MRC)
bull MRC is the best performance improvement compared with the other methods
bull However the trade off is It requires 1 cophasing 2 weighting 3summing circuitsResulting in most complicated implementationComplexity performance
(b) Equal Gain Combining (EGC)
EGCbull EGC is similar to MRC except the weighting
circuits are omittedbull The performance improvement obtained by
equal gain combiner is slightly inferior to that of a MRC since the interference and noise corrupted signal combined with high quality signals
For VHF UHF and microwave wireless radio applications
bull Both MRC and EGC methods are unsuitablebull Compared with MRC EGC methods the
selection method is more suitable for mobile radio applications because of its simple implementation
(c) Selection or Switching Combining
bull The diversity branch having the highest signal level (or) lowest Pe is selected
bull Also in addition stable operation is easily achieved even in the fast multipath fading environments
bull But the performance improvement obtained by the selection method is still only slightly inferior to that of MRC method
Disadvantage of Selection or Switching
bull Combining The continuous monitoring of the signals requires the same no of receivers as the no of diversity branches
bull This redundancy can be alleviated by the use of switching or scanning receiver
SWITCHNINGMETHODS
FIXED THERSHOLD VARIABLE THERSHOLD
(a) Switching Methods with Fixed threshold
bull The switching from one branch to the other occurs when the signal level falls below a threshold value
bull The threshold value is fixedbull However this threshold value is not
necessarily the best over the entire service area
FIXED THERSHOLD
(b) Switching Methods with Variable threshold
bull Here the threshold value is adjusted dynamically as the vehicle moves
bull It includes the feedback using Estimationbull But it may introduce the envelope and phase
transients that will reduce the performance improvement
VARIABLE THERSHOLD
Conclusions
bull The diversity is used to provide the receiver with several replicas of the same signal
bull Diversity techniques are used to improve the performance of the radio channel without any increase in the transmitted power
bull As higher as the received signal replicas are decorrelated as much as the diversity gain
Thank you for you attention
- No trade off to
- What are all the needs of diversity techniques
- CONCEPTS OF DIVERSITY BRANCH AND SIGNAL PATH
- (a) Branch Construction method using frequency diversity
- (b) Branch Construction method using Time diversity
- COMBINING AND SWITCHNING METHODS
- Slide 29
- FOR COHERENT DETECTION
- (a) Maximal ratio combining (MRC)
- Slide 32
- (b) Equal Gain Combining (EGC)
- EGC
- For VHF UHF and microwave wireless radio applications
- (c) Selection or Switching Combining
- Slide 37
- Disadvantage of Selection or Switching
- Slide 39
- (a) Switching Methods with Fixed threshold
- Slide 41
- (b) Switching Methods with Variable threshold
- Slide 43
-
DIVERSITY as far as mobile
wireless radio systems are
concerned
Common assumption
bull Common assumption
signals that scatter off of different objects fade independently
How when diversity is created
bull Diversity is created when these signals are separated in the receiver
Examples
RAKE receiver - - separates paths by delay [PATH DIVERSITY]
Multi beam antenna - - separates paths by angle [ANGLE DIVERSITY]
change the relative phases of the multi pathsignals
bull Examplesbull 1048672Identical antennas slightly different locations[SPACE DIVERSITY]bull 1048672Same signal received on different RF carriers[FREQUENCY DIVERSITY] Required carrier
separation depends inversely on delay spread
Another way to create diversity
Still other ways to generate diversity
bull Dual polarized antennas [POLARIZATION DIVERSITY]
Introduction
bull Fading
Signal fluctuations caused by multipath propagation and shadowing effects
bull Diversity
Receiving the same information bearing signal over 2 or more fading channels
Introduction (contrsquod)
bull SpaceTransmission using multiple transmitreceive antennas
bull FrequencyTransmission using multiple frequency channels separated by at least the coherence bandwidth
bull Time Transmission using multiple time slots separated by at least the coherence time
Spatial diversity
bull Single-input single-output (SISO) channel
No spatial diversitybull Single-input multiple-output (SIMO) channel
Receive diversitybull Multiple-input single-output (MISO) channel
Transmit diversity bull Multiple-input multiple-output (MIMO) channel
Combined transmit and receive diversity
The following classes of diversity schemes can be identified
1Space diversity 2Polarization diversity 3Frequency diversity 4Time diversity 5Angle or direction diversity
1] Space diversity
bull The signal is transferred over several different propagation paths
bull In the case of wired transmission this can be achieved by transmitting via multiple wires
bull In the case of wireless transmission it can be achieved by antenna diversity using multiple transmitter antennas (transmit diversity) andor multiple receiving antennas (reception diversity)
bull In the latter case a diversity combining technique is applied before further signal processing takes place
2] Polarization diversity
bull Polarization diversity Multiple versions of a signal are transmitted and received via antennas with different polarization
bull A diversity combining technique is applied on the receiver side
POLARIZER
3] Frequency diversity
bull Frequency diversity The signal is transferred using several frequency channels or spread over a wide spectrum that is affected by frequency-selective fading
bull Middle-late 20th century microwave radio relay lines often used several regular wideband radio channels and one protection channel for automatic use by any faded channel Later examples include OFDM modulation in combination with subcarrier interleaving and
forward error correction Spread spectrum for example frequency hopping or DS-CDMA
4] Time diversity
bull Time diversity Multiple versions of the same signal are transmitted at different time instants
Terrestrial microwave radio system with two antenna arrays configured for space-diversity
Diversity Combining
bull Once you have created two or morediversity channels what do you do with them
Spatial diversity (contrsquod)
bullMaximum ratio combining (MRC)
h1
h2
h1
h2
yx
Combining schemes
bullSelection combining (SC)
h1
h2
yx
MonitorSNR
Selectbranch
Switch-and-stay combining (SSC) Switch-and-examine combining (SEC)
h1
h2
x
ComparatorChannelestimator
switchingthreshold
bullSwitched diversity
No trade off to
Without excessively increasing
bull 1 transmitting powerbull 2 Co-channel reuse distance
bull One of the most effective technique to solve this issue is diversity reception technique
What are all the needs of diversity techniques
bull 1No of signal transmission pathsbull 2A circuit to combine the received signal or
select one of them
CONCEPTS OF DIVERSITY BRANCH AND SIGNAL PATH
(a) Branch Construction method using frequency diversity
(b) Branch Construction method using Time diversity
COMBINING AND SWITCHNING METHODS
COMBINING AND SWITCHNINGMETHODS
FOR COHERENT DETECTION
FOR NON - COHERENT DETECTION
FOR COHERENT DETECTION
bull There is no difference whether the combining is carried out in the pre detection or in the post detection stage
FOR NON-COHERENT DETECTION
bull There is a difference in performance exists between whether pre detection amp post detection combining methods
(a) Maximal ratio combining (MRC)
bull MRC is the best performance improvement compared with the other methods
bull However the trade off is It requires 1 cophasing 2 weighting 3summing circuitsResulting in most complicated implementationComplexity performance
(b) Equal Gain Combining (EGC)
EGCbull EGC is similar to MRC except the weighting
circuits are omittedbull The performance improvement obtained by
equal gain combiner is slightly inferior to that of a MRC since the interference and noise corrupted signal combined with high quality signals
For VHF UHF and microwave wireless radio applications
bull Both MRC and EGC methods are unsuitablebull Compared with MRC EGC methods the
selection method is more suitable for mobile radio applications because of its simple implementation
(c) Selection or Switching Combining
bull The diversity branch having the highest signal level (or) lowest Pe is selected
bull Also in addition stable operation is easily achieved even in the fast multipath fading environments
bull But the performance improvement obtained by the selection method is still only slightly inferior to that of MRC method
Disadvantage of Selection or Switching
bull Combining The continuous monitoring of the signals requires the same no of receivers as the no of diversity branches
bull This redundancy can be alleviated by the use of switching or scanning receiver
SWITCHNINGMETHODS
FIXED THERSHOLD VARIABLE THERSHOLD
(a) Switching Methods with Fixed threshold
bull The switching from one branch to the other occurs when the signal level falls below a threshold value
bull The threshold value is fixedbull However this threshold value is not
necessarily the best over the entire service area
FIXED THERSHOLD
(b) Switching Methods with Variable threshold
bull Here the threshold value is adjusted dynamically as the vehicle moves
bull It includes the feedback using Estimationbull But it may introduce the envelope and phase
transients that will reduce the performance improvement
VARIABLE THERSHOLD
Conclusions
bull The diversity is used to provide the receiver with several replicas of the same signal
bull Diversity techniques are used to improve the performance of the radio channel without any increase in the transmitted power
bull As higher as the received signal replicas are decorrelated as much as the diversity gain
Thank you for you attention
- No trade off to
- What are all the needs of diversity techniques
- CONCEPTS OF DIVERSITY BRANCH AND SIGNAL PATH
- (a) Branch Construction method using frequency diversity
- (b) Branch Construction method using Time diversity
- COMBINING AND SWITCHNING METHODS
- Slide 29
- FOR COHERENT DETECTION
- (a) Maximal ratio combining (MRC)
- Slide 32
- (b) Equal Gain Combining (EGC)
- EGC
- For VHF UHF and microwave wireless radio applications
- (c) Selection or Switching Combining
- Slide 37
- Disadvantage of Selection or Switching
- Slide 39
- (a) Switching Methods with Fixed threshold
- Slide 41
- (b) Switching Methods with Variable threshold
- Slide 43
-
Common assumption
bull Common assumption
signals that scatter off of different objects fade independently
How when diversity is created
bull Diversity is created when these signals are separated in the receiver
Examples
RAKE receiver - - separates paths by delay [PATH DIVERSITY]
Multi beam antenna - - separates paths by angle [ANGLE DIVERSITY]
change the relative phases of the multi pathsignals
bull Examplesbull 1048672Identical antennas slightly different locations[SPACE DIVERSITY]bull 1048672Same signal received on different RF carriers[FREQUENCY DIVERSITY] Required carrier
separation depends inversely on delay spread
Another way to create diversity
Still other ways to generate diversity
bull Dual polarized antennas [POLARIZATION DIVERSITY]
Introduction
bull Fading
Signal fluctuations caused by multipath propagation and shadowing effects
bull Diversity
Receiving the same information bearing signal over 2 or more fading channels
Introduction (contrsquod)
bull SpaceTransmission using multiple transmitreceive antennas
bull FrequencyTransmission using multiple frequency channels separated by at least the coherence bandwidth
bull Time Transmission using multiple time slots separated by at least the coherence time
Spatial diversity
bull Single-input single-output (SISO) channel
No spatial diversitybull Single-input multiple-output (SIMO) channel
Receive diversitybull Multiple-input single-output (MISO) channel
Transmit diversity bull Multiple-input multiple-output (MIMO) channel
Combined transmit and receive diversity
The following classes of diversity schemes can be identified
1Space diversity 2Polarization diversity 3Frequency diversity 4Time diversity 5Angle or direction diversity
1] Space diversity
bull The signal is transferred over several different propagation paths
bull In the case of wired transmission this can be achieved by transmitting via multiple wires
bull In the case of wireless transmission it can be achieved by antenna diversity using multiple transmitter antennas (transmit diversity) andor multiple receiving antennas (reception diversity)
bull In the latter case a diversity combining technique is applied before further signal processing takes place
2] Polarization diversity
bull Polarization diversity Multiple versions of a signal are transmitted and received via antennas with different polarization
bull A diversity combining technique is applied on the receiver side
POLARIZER
3] Frequency diversity
bull Frequency diversity The signal is transferred using several frequency channels or spread over a wide spectrum that is affected by frequency-selective fading
bull Middle-late 20th century microwave radio relay lines often used several regular wideband radio channels and one protection channel for automatic use by any faded channel Later examples include OFDM modulation in combination with subcarrier interleaving and
forward error correction Spread spectrum for example frequency hopping or DS-CDMA
4] Time diversity
bull Time diversity Multiple versions of the same signal are transmitted at different time instants
Terrestrial microwave radio system with two antenna arrays configured for space-diversity
Diversity Combining
bull Once you have created two or morediversity channels what do you do with them
Spatial diversity (contrsquod)
bullMaximum ratio combining (MRC)
h1
h2
h1
h2
yx
Combining schemes
bullSelection combining (SC)
h1
h2
yx
MonitorSNR
Selectbranch
Switch-and-stay combining (SSC) Switch-and-examine combining (SEC)
h1
h2
x
ComparatorChannelestimator
switchingthreshold
bullSwitched diversity
No trade off to
Without excessively increasing
bull 1 transmitting powerbull 2 Co-channel reuse distance
bull One of the most effective technique to solve this issue is diversity reception technique
What are all the needs of diversity techniques
bull 1No of signal transmission pathsbull 2A circuit to combine the received signal or
select one of them
CONCEPTS OF DIVERSITY BRANCH AND SIGNAL PATH
(a) Branch Construction method using frequency diversity
(b) Branch Construction method using Time diversity
COMBINING AND SWITCHNING METHODS
COMBINING AND SWITCHNINGMETHODS
FOR COHERENT DETECTION
FOR NON - COHERENT DETECTION
FOR COHERENT DETECTION
bull There is no difference whether the combining is carried out in the pre detection or in the post detection stage
FOR NON-COHERENT DETECTION
bull There is a difference in performance exists between whether pre detection amp post detection combining methods
(a) Maximal ratio combining (MRC)
bull MRC is the best performance improvement compared with the other methods
bull However the trade off is It requires 1 cophasing 2 weighting 3summing circuitsResulting in most complicated implementationComplexity performance
(b) Equal Gain Combining (EGC)
EGCbull EGC is similar to MRC except the weighting
circuits are omittedbull The performance improvement obtained by
equal gain combiner is slightly inferior to that of a MRC since the interference and noise corrupted signal combined with high quality signals
For VHF UHF and microwave wireless radio applications
bull Both MRC and EGC methods are unsuitablebull Compared with MRC EGC methods the
selection method is more suitable for mobile radio applications because of its simple implementation
(c) Selection or Switching Combining
bull The diversity branch having the highest signal level (or) lowest Pe is selected
bull Also in addition stable operation is easily achieved even in the fast multipath fading environments
bull But the performance improvement obtained by the selection method is still only slightly inferior to that of MRC method
Disadvantage of Selection or Switching
bull Combining The continuous monitoring of the signals requires the same no of receivers as the no of diversity branches
bull This redundancy can be alleviated by the use of switching or scanning receiver
SWITCHNINGMETHODS
FIXED THERSHOLD VARIABLE THERSHOLD
(a) Switching Methods with Fixed threshold
bull The switching from one branch to the other occurs when the signal level falls below a threshold value
bull The threshold value is fixedbull However this threshold value is not
necessarily the best over the entire service area
FIXED THERSHOLD
(b) Switching Methods with Variable threshold
bull Here the threshold value is adjusted dynamically as the vehicle moves
bull It includes the feedback using Estimationbull But it may introduce the envelope and phase
transients that will reduce the performance improvement
VARIABLE THERSHOLD
Conclusions
bull The diversity is used to provide the receiver with several replicas of the same signal
bull Diversity techniques are used to improve the performance of the radio channel without any increase in the transmitted power
bull As higher as the received signal replicas are decorrelated as much as the diversity gain
Thank you for you attention
- No trade off to
- What are all the needs of diversity techniques
- CONCEPTS OF DIVERSITY BRANCH AND SIGNAL PATH
- (a) Branch Construction method using frequency diversity
- (b) Branch Construction method using Time diversity
- COMBINING AND SWITCHNING METHODS
- Slide 29
- FOR COHERENT DETECTION
- (a) Maximal ratio combining (MRC)
- Slide 32
- (b) Equal Gain Combining (EGC)
- EGC
- For VHF UHF and microwave wireless radio applications
- (c) Selection or Switching Combining
- Slide 37
- Disadvantage of Selection or Switching
- Slide 39
- (a) Switching Methods with Fixed threshold
- Slide 41
- (b) Switching Methods with Variable threshold
- Slide 43
-
How when diversity is created
bull Diversity is created when these signals are separated in the receiver
Examples
RAKE receiver - - separates paths by delay [PATH DIVERSITY]
Multi beam antenna - - separates paths by angle [ANGLE DIVERSITY]
change the relative phases of the multi pathsignals
bull Examplesbull 1048672Identical antennas slightly different locations[SPACE DIVERSITY]bull 1048672Same signal received on different RF carriers[FREQUENCY DIVERSITY] Required carrier
separation depends inversely on delay spread
Another way to create diversity
Still other ways to generate diversity
bull Dual polarized antennas [POLARIZATION DIVERSITY]
Introduction
bull Fading
Signal fluctuations caused by multipath propagation and shadowing effects
bull Diversity
Receiving the same information bearing signal over 2 or more fading channels
Introduction (contrsquod)
bull SpaceTransmission using multiple transmitreceive antennas
bull FrequencyTransmission using multiple frequency channels separated by at least the coherence bandwidth
bull Time Transmission using multiple time slots separated by at least the coherence time
Spatial diversity
bull Single-input single-output (SISO) channel
No spatial diversitybull Single-input multiple-output (SIMO) channel
Receive diversitybull Multiple-input single-output (MISO) channel
Transmit diversity bull Multiple-input multiple-output (MIMO) channel
Combined transmit and receive diversity
The following classes of diversity schemes can be identified
1Space diversity 2Polarization diversity 3Frequency diversity 4Time diversity 5Angle or direction diversity
1] Space diversity
bull The signal is transferred over several different propagation paths
bull In the case of wired transmission this can be achieved by transmitting via multiple wires
bull In the case of wireless transmission it can be achieved by antenna diversity using multiple transmitter antennas (transmit diversity) andor multiple receiving antennas (reception diversity)
bull In the latter case a diversity combining technique is applied before further signal processing takes place
2] Polarization diversity
bull Polarization diversity Multiple versions of a signal are transmitted and received via antennas with different polarization
bull A diversity combining technique is applied on the receiver side
POLARIZER
3] Frequency diversity
bull Frequency diversity The signal is transferred using several frequency channels or spread over a wide spectrum that is affected by frequency-selective fading
bull Middle-late 20th century microwave radio relay lines often used several regular wideband radio channels and one protection channel for automatic use by any faded channel Later examples include OFDM modulation in combination with subcarrier interleaving and
forward error correction Spread spectrum for example frequency hopping or DS-CDMA
4] Time diversity
bull Time diversity Multiple versions of the same signal are transmitted at different time instants
Terrestrial microwave radio system with two antenna arrays configured for space-diversity
Diversity Combining
bull Once you have created two or morediversity channels what do you do with them
Spatial diversity (contrsquod)
bullMaximum ratio combining (MRC)
h1
h2
h1
h2
yx
Combining schemes
bullSelection combining (SC)
h1
h2
yx
MonitorSNR
Selectbranch
Switch-and-stay combining (SSC) Switch-and-examine combining (SEC)
h1
h2
x
ComparatorChannelestimator
switchingthreshold
bullSwitched diversity
No trade off to
Without excessively increasing
bull 1 transmitting powerbull 2 Co-channel reuse distance
bull One of the most effective technique to solve this issue is diversity reception technique
What are all the needs of diversity techniques
bull 1No of signal transmission pathsbull 2A circuit to combine the received signal or
select one of them
CONCEPTS OF DIVERSITY BRANCH AND SIGNAL PATH
(a) Branch Construction method using frequency diversity
(b) Branch Construction method using Time diversity
COMBINING AND SWITCHNING METHODS
COMBINING AND SWITCHNINGMETHODS
FOR COHERENT DETECTION
FOR NON - COHERENT DETECTION
FOR COHERENT DETECTION
bull There is no difference whether the combining is carried out in the pre detection or in the post detection stage
FOR NON-COHERENT DETECTION
bull There is a difference in performance exists between whether pre detection amp post detection combining methods
(a) Maximal ratio combining (MRC)
bull MRC is the best performance improvement compared with the other methods
bull However the trade off is It requires 1 cophasing 2 weighting 3summing circuitsResulting in most complicated implementationComplexity performance
(b) Equal Gain Combining (EGC)
EGCbull EGC is similar to MRC except the weighting
circuits are omittedbull The performance improvement obtained by
equal gain combiner is slightly inferior to that of a MRC since the interference and noise corrupted signal combined with high quality signals
For VHF UHF and microwave wireless radio applications
bull Both MRC and EGC methods are unsuitablebull Compared with MRC EGC methods the
selection method is more suitable for mobile radio applications because of its simple implementation
(c) Selection or Switching Combining
bull The diversity branch having the highest signal level (or) lowest Pe is selected
bull Also in addition stable operation is easily achieved even in the fast multipath fading environments
bull But the performance improvement obtained by the selection method is still only slightly inferior to that of MRC method
Disadvantage of Selection or Switching
bull Combining The continuous monitoring of the signals requires the same no of receivers as the no of diversity branches
bull This redundancy can be alleviated by the use of switching or scanning receiver
SWITCHNINGMETHODS
FIXED THERSHOLD VARIABLE THERSHOLD
(a) Switching Methods with Fixed threshold
bull The switching from one branch to the other occurs when the signal level falls below a threshold value
bull The threshold value is fixedbull However this threshold value is not
necessarily the best over the entire service area
FIXED THERSHOLD
(b) Switching Methods with Variable threshold
bull Here the threshold value is adjusted dynamically as the vehicle moves
bull It includes the feedback using Estimationbull But it may introduce the envelope and phase
transients that will reduce the performance improvement
VARIABLE THERSHOLD
Conclusions
bull The diversity is used to provide the receiver with several replicas of the same signal
bull Diversity techniques are used to improve the performance of the radio channel without any increase in the transmitted power
bull As higher as the received signal replicas are decorrelated as much as the diversity gain
Thank you for you attention
- No trade off to
- What are all the needs of diversity techniques
- CONCEPTS OF DIVERSITY BRANCH AND SIGNAL PATH
- (a) Branch Construction method using frequency diversity
- (b) Branch Construction method using Time diversity
- COMBINING AND SWITCHNING METHODS
- Slide 29
- FOR COHERENT DETECTION
- (a) Maximal ratio combining (MRC)
- Slide 32
- (b) Equal Gain Combining (EGC)
- EGC
- For VHF UHF and microwave wireless radio applications
- (c) Selection or Switching Combining
- Slide 37
- Disadvantage of Selection or Switching
- Slide 39
- (a) Switching Methods with Fixed threshold
- Slide 41
- (b) Switching Methods with Variable threshold
- Slide 43
-
change the relative phases of the multi pathsignals
bull Examplesbull 1048672Identical antennas slightly different locations[SPACE DIVERSITY]bull 1048672Same signal received on different RF carriers[FREQUENCY DIVERSITY] Required carrier
separation depends inversely on delay spread
Another way to create diversity
Still other ways to generate diversity
bull Dual polarized antennas [POLARIZATION DIVERSITY]
Introduction
bull Fading
Signal fluctuations caused by multipath propagation and shadowing effects
bull Diversity
Receiving the same information bearing signal over 2 or more fading channels
Introduction (contrsquod)
bull SpaceTransmission using multiple transmitreceive antennas
bull FrequencyTransmission using multiple frequency channels separated by at least the coherence bandwidth
bull Time Transmission using multiple time slots separated by at least the coherence time
Spatial diversity
bull Single-input single-output (SISO) channel
No spatial diversitybull Single-input multiple-output (SIMO) channel
Receive diversitybull Multiple-input single-output (MISO) channel
Transmit diversity bull Multiple-input multiple-output (MIMO) channel
Combined transmit and receive diversity
The following classes of diversity schemes can be identified
1Space diversity 2Polarization diversity 3Frequency diversity 4Time diversity 5Angle or direction diversity
1] Space diversity
bull The signal is transferred over several different propagation paths
bull In the case of wired transmission this can be achieved by transmitting via multiple wires
bull In the case of wireless transmission it can be achieved by antenna diversity using multiple transmitter antennas (transmit diversity) andor multiple receiving antennas (reception diversity)
bull In the latter case a diversity combining technique is applied before further signal processing takes place
2] Polarization diversity
bull Polarization diversity Multiple versions of a signal are transmitted and received via antennas with different polarization
bull A diversity combining technique is applied on the receiver side
POLARIZER
3] Frequency diversity
bull Frequency diversity The signal is transferred using several frequency channels or spread over a wide spectrum that is affected by frequency-selective fading
bull Middle-late 20th century microwave radio relay lines often used several regular wideband radio channels and one protection channel for automatic use by any faded channel Later examples include OFDM modulation in combination with subcarrier interleaving and
forward error correction Spread spectrum for example frequency hopping or DS-CDMA
4] Time diversity
bull Time diversity Multiple versions of the same signal are transmitted at different time instants
Terrestrial microwave radio system with two antenna arrays configured for space-diversity
Diversity Combining
bull Once you have created two or morediversity channels what do you do with them
Spatial diversity (contrsquod)
bullMaximum ratio combining (MRC)
h1
h2
h1
h2
yx
Combining schemes
bullSelection combining (SC)
h1
h2
yx
MonitorSNR
Selectbranch
Switch-and-stay combining (SSC) Switch-and-examine combining (SEC)
h1
h2
x
ComparatorChannelestimator
switchingthreshold
bullSwitched diversity
No trade off to
Without excessively increasing
bull 1 transmitting powerbull 2 Co-channel reuse distance
bull One of the most effective technique to solve this issue is diversity reception technique
What are all the needs of diversity techniques
bull 1No of signal transmission pathsbull 2A circuit to combine the received signal or
select one of them
CONCEPTS OF DIVERSITY BRANCH AND SIGNAL PATH
(a) Branch Construction method using frequency diversity
(b) Branch Construction method using Time diversity
COMBINING AND SWITCHNING METHODS
COMBINING AND SWITCHNINGMETHODS
FOR COHERENT DETECTION
FOR NON - COHERENT DETECTION
FOR COHERENT DETECTION
bull There is no difference whether the combining is carried out in the pre detection or in the post detection stage
FOR NON-COHERENT DETECTION
bull There is a difference in performance exists between whether pre detection amp post detection combining methods
(a) Maximal ratio combining (MRC)
bull MRC is the best performance improvement compared with the other methods
bull However the trade off is It requires 1 cophasing 2 weighting 3summing circuitsResulting in most complicated implementationComplexity performance
(b) Equal Gain Combining (EGC)
EGCbull EGC is similar to MRC except the weighting
circuits are omittedbull The performance improvement obtained by
equal gain combiner is slightly inferior to that of a MRC since the interference and noise corrupted signal combined with high quality signals
For VHF UHF and microwave wireless radio applications
bull Both MRC and EGC methods are unsuitablebull Compared with MRC EGC methods the
selection method is more suitable for mobile radio applications because of its simple implementation
(c) Selection or Switching Combining
bull The diversity branch having the highest signal level (or) lowest Pe is selected
bull Also in addition stable operation is easily achieved even in the fast multipath fading environments
bull But the performance improvement obtained by the selection method is still only slightly inferior to that of MRC method
Disadvantage of Selection or Switching
bull Combining The continuous monitoring of the signals requires the same no of receivers as the no of diversity branches
bull This redundancy can be alleviated by the use of switching or scanning receiver
SWITCHNINGMETHODS
FIXED THERSHOLD VARIABLE THERSHOLD
(a) Switching Methods with Fixed threshold
bull The switching from one branch to the other occurs when the signal level falls below a threshold value
bull The threshold value is fixedbull However this threshold value is not
necessarily the best over the entire service area
FIXED THERSHOLD
(b) Switching Methods with Variable threshold
bull Here the threshold value is adjusted dynamically as the vehicle moves
bull It includes the feedback using Estimationbull But it may introduce the envelope and phase
transients that will reduce the performance improvement
VARIABLE THERSHOLD
Conclusions
bull The diversity is used to provide the receiver with several replicas of the same signal
bull Diversity techniques are used to improve the performance of the radio channel without any increase in the transmitted power
bull As higher as the received signal replicas are decorrelated as much as the diversity gain
Thank you for you attention
- No trade off to
- What are all the needs of diversity techniques
- CONCEPTS OF DIVERSITY BRANCH AND SIGNAL PATH
- (a) Branch Construction method using frequency diversity
- (b) Branch Construction method using Time diversity
- COMBINING AND SWITCHNING METHODS
- Slide 29
- FOR COHERENT DETECTION
- (a) Maximal ratio combining (MRC)
- Slide 32
- (b) Equal Gain Combining (EGC)
- EGC
- For VHF UHF and microwave wireless radio applications
- (c) Selection or Switching Combining
- Slide 37
- Disadvantage of Selection or Switching
- Slide 39
- (a) Switching Methods with Fixed threshold
- Slide 41
- (b) Switching Methods with Variable threshold
- Slide 43
-
Still other ways to generate diversity
bull Dual polarized antennas [POLARIZATION DIVERSITY]
Introduction
bull Fading
Signal fluctuations caused by multipath propagation and shadowing effects
bull Diversity
Receiving the same information bearing signal over 2 or more fading channels
Introduction (contrsquod)
bull SpaceTransmission using multiple transmitreceive antennas
bull FrequencyTransmission using multiple frequency channels separated by at least the coherence bandwidth
bull Time Transmission using multiple time slots separated by at least the coherence time
Spatial diversity
bull Single-input single-output (SISO) channel
No spatial diversitybull Single-input multiple-output (SIMO) channel
Receive diversitybull Multiple-input single-output (MISO) channel
Transmit diversity bull Multiple-input multiple-output (MIMO) channel
Combined transmit and receive diversity
The following classes of diversity schemes can be identified
1Space diversity 2Polarization diversity 3Frequency diversity 4Time diversity 5Angle or direction diversity
1] Space diversity
bull The signal is transferred over several different propagation paths
bull In the case of wired transmission this can be achieved by transmitting via multiple wires
bull In the case of wireless transmission it can be achieved by antenna diversity using multiple transmitter antennas (transmit diversity) andor multiple receiving antennas (reception diversity)
bull In the latter case a diversity combining technique is applied before further signal processing takes place
2] Polarization diversity
bull Polarization diversity Multiple versions of a signal are transmitted and received via antennas with different polarization
bull A diversity combining technique is applied on the receiver side
POLARIZER
3] Frequency diversity
bull Frequency diversity The signal is transferred using several frequency channels or spread over a wide spectrum that is affected by frequency-selective fading
bull Middle-late 20th century microwave radio relay lines often used several regular wideband radio channels and one protection channel for automatic use by any faded channel Later examples include OFDM modulation in combination with subcarrier interleaving and
forward error correction Spread spectrum for example frequency hopping or DS-CDMA
4] Time diversity
bull Time diversity Multiple versions of the same signal are transmitted at different time instants
Terrestrial microwave radio system with two antenna arrays configured for space-diversity
Diversity Combining
bull Once you have created two or morediversity channels what do you do with them
Spatial diversity (contrsquod)
bullMaximum ratio combining (MRC)
h1
h2
h1
h2
yx
Combining schemes
bullSelection combining (SC)
h1
h2
yx
MonitorSNR
Selectbranch
Switch-and-stay combining (SSC) Switch-and-examine combining (SEC)
h1
h2
x
ComparatorChannelestimator
switchingthreshold
bullSwitched diversity
No trade off to
Without excessively increasing
bull 1 transmitting powerbull 2 Co-channel reuse distance
bull One of the most effective technique to solve this issue is diversity reception technique
What are all the needs of diversity techniques
bull 1No of signal transmission pathsbull 2A circuit to combine the received signal or
select one of them
CONCEPTS OF DIVERSITY BRANCH AND SIGNAL PATH
(a) Branch Construction method using frequency diversity
(b) Branch Construction method using Time diversity
COMBINING AND SWITCHNING METHODS
COMBINING AND SWITCHNINGMETHODS
FOR COHERENT DETECTION
FOR NON - COHERENT DETECTION
FOR COHERENT DETECTION
bull There is no difference whether the combining is carried out in the pre detection or in the post detection stage
FOR NON-COHERENT DETECTION
bull There is a difference in performance exists between whether pre detection amp post detection combining methods
(a) Maximal ratio combining (MRC)
bull MRC is the best performance improvement compared with the other methods
bull However the trade off is It requires 1 cophasing 2 weighting 3summing circuitsResulting in most complicated implementationComplexity performance
(b) Equal Gain Combining (EGC)
EGCbull EGC is similar to MRC except the weighting
circuits are omittedbull The performance improvement obtained by
equal gain combiner is slightly inferior to that of a MRC since the interference and noise corrupted signal combined with high quality signals
For VHF UHF and microwave wireless radio applications
bull Both MRC and EGC methods are unsuitablebull Compared with MRC EGC methods the
selection method is more suitable for mobile radio applications because of its simple implementation
(c) Selection or Switching Combining
bull The diversity branch having the highest signal level (or) lowest Pe is selected
bull Also in addition stable operation is easily achieved even in the fast multipath fading environments
bull But the performance improvement obtained by the selection method is still only slightly inferior to that of MRC method
Disadvantage of Selection or Switching
bull Combining The continuous monitoring of the signals requires the same no of receivers as the no of diversity branches
bull This redundancy can be alleviated by the use of switching or scanning receiver
SWITCHNINGMETHODS
FIXED THERSHOLD VARIABLE THERSHOLD
(a) Switching Methods with Fixed threshold
bull The switching from one branch to the other occurs when the signal level falls below a threshold value
bull The threshold value is fixedbull However this threshold value is not
necessarily the best over the entire service area
FIXED THERSHOLD
(b) Switching Methods with Variable threshold
bull Here the threshold value is adjusted dynamically as the vehicle moves
bull It includes the feedback using Estimationbull But it may introduce the envelope and phase
transients that will reduce the performance improvement
VARIABLE THERSHOLD
Conclusions
bull The diversity is used to provide the receiver with several replicas of the same signal
bull Diversity techniques are used to improve the performance of the radio channel without any increase in the transmitted power
bull As higher as the received signal replicas are decorrelated as much as the diversity gain
Thank you for you attention
- No trade off to
- What are all the needs of diversity techniques
- CONCEPTS OF DIVERSITY BRANCH AND SIGNAL PATH
- (a) Branch Construction method using frequency diversity
- (b) Branch Construction method using Time diversity
- COMBINING AND SWITCHNING METHODS
- Slide 29
- FOR COHERENT DETECTION
- (a) Maximal ratio combining (MRC)
- Slide 32
- (b) Equal Gain Combining (EGC)
- EGC
- For VHF UHF and microwave wireless radio applications
- (c) Selection or Switching Combining
- Slide 37
- Disadvantage of Selection or Switching
- Slide 39
- (a) Switching Methods with Fixed threshold
- Slide 41
- (b) Switching Methods with Variable threshold
- Slide 43
-
Introduction
bull Fading
Signal fluctuations caused by multipath propagation and shadowing effects
bull Diversity
Receiving the same information bearing signal over 2 or more fading channels
Introduction (contrsquod)
bull SpaceTransmission using multiple transmitreceive antennas
bull FrequencyTransmission using multiple frequency channels separated by at least the coherence bandwidth
bull Time Transmission using multiple time slots separated by at least the coherence time
Spatial diversity
bull Single-input single-output (SISO) channel
No spatial diversitybull Single-input multiple-output (SIMO) channel
Receive diversitybull Multiple-input single-output (MISO) channel
Transmit diversity bull Multiple-input multiple-output (MIMO) channel
Combined transmit and receive diversity
The following classes of diversity schemes can be identified
1Space diversity 2Polarization diversity 3Frequency diversity 4Time diversity 5Angle or direction diversity
1] Space diversity
bull The signal is transferred over several different propagation paths
bull In the case of wired transmission this can be achieved by transmitting via multiple wires
bull In the case of wireless transmission it can be achieved by antenna diversity using multiple transmitter antennas (transmit diversity) andor multiple receiving antennas (reception diversity)
bull In the latter case a diversity combining technique is applied before further signal processing takes place
2] Polarization diversity
bull Polarization diversity Multiple versions of a signal are transmitted and received via antennas with different polarization
bull A diversity combining technique is applied on the receiver side
POLARIZER
3] Frequency diversity
bull Frequency diversity The signal is transferred using several frequency channels or spread over a wide spectrum that is affected by frequency-selective fading
bull Middle-late 20th century microwave radio relay lines often used several regular wideband radio channels and one protection channel for automatic use by any faded channel Later examples include OFDM modulation in combination with subcarrier interleaving and
forward error correction Spread spectrum for example frequency hopping or DS-CDMA
4] Time diversity
bull Time diversity Multiple versions of the same signal are transmitted at different time instants
Terrestrial microwave radio system with two antenna arrays configured for space-diversity
Diversity Combining
bull Once you have created two or morediversity channels what do you do with them
Spatial diversity (contrsquod)
bullMaximum ratio combining (MRC)
h1
h2
h1
h2
yx
Combining schemes
bullSelection combining (SC)
h1
h2
yx
MonitorSNR
Selectbranch
Switch-and-stay combining (SSC) Switch-and-examine combining (SEC)
h1
h2
x
ComparatorChannelestimator
switchingthreshold
bullSwitched diversity
No trade off to
Without excessively increasing
bull 1 transmitting powerbull 2 Co-channel reuse distance
bull One of the most effective technique to solve this issue is diversity reception technique
What are all the needs of diversity techniques
bull 1No of signal transmission pathsbull 2A circuit to combine the received signal or
select one of them
CONCEPTS OF DIVERSITY BRANCH AND SIGNAL PATH
(a) Branch Construction method using frequency diversity
(b) Branch Construction method using Time diversity
COMBINING AND SWITCHNING METHODS
COMBINING AND SWITCHNINGMETHODS
FOR COHERENT DETECTION
FOR NON - COHERENT DETECTION
FOR COHERENT DETECTION
bull There is no difference whether the combining is carried out in the pre detection or in the post detection stage
FOR NON-COHERENT DETECTION
bull There is a difference in performance exists between whether pre detection amp post detection combining methods
(a) Maximal ratio combining (MRC)
bull MRC is the best performance improvement compared with the other methods
bull However the trade off is It requires 1 cophasing 2 weighting 3summing circuitsResulting in most complicated implementationComplexity performance
(b) Equal Gain Combining (EGC)
EGCbull EGC is similar to MRC except the weighting
circuits are omittedbull The performance improvement obtained by
equal gain combiner is slightly inferior to that of a MRC since the interference and noise corrupted signal combined with high quality signals
For VHF UHF and microwave wireless radio applications
bull Both MRC and EGC methods are unsuitablebull Compared with MRC EGC methods the
selection method is more suitable for mobile radio applications because of its simple implementation
(c) Selection or Switching Combining
bull The diversity branch having the highest signal level (or) lowest Pe is selected
bull Also in addition stable operation is easily achieved even in the fast multipath fading environments
bull But the performance improvement obtained by the selection method is still only slightly inferior to that of MRC method
Disadvantage of Selection or Switching
bull Combining The continuous monitoring of the signals requires the same no of receivers as the no of diversity branches
bull This redundancy can be alleviated by the use of switching or scanning receiver
SWITCHNINGMETHODS
FIXED THERSHOLD VARIABLE THERSHOLD
(a) Switching Methods with Fixed threshold
bull The switching from one branch to the other occurs when the signal level falls below a threshold value
bull The threshold value is fixedbull However this threshold value is not
necessarily the best over the entire service area
FIXED THERSHOLD
(b) Switching Methods with Variable threshold
bull Here the threshold value is adjusted dynamically as the vehicle moves
bull It includes the feedback using Estimationbull But it may introduce the envelope and phase
transients that will reduce the performance improvement
VARIABLE THERSHOLD
Conclusions
bull The diversity is used to provide the receiver with several replicas of the same signal
bull Diversity techniques are used to improve the performance of the radio channel without any increase in the transmitted power
bull As higher as the received signal replicas are decorrelated as much as the diversity gain
Thank you for you attention
- No trade off to
- What are all the needs of diversity techniques
- CONCEPTS OF DIVERSITY BRANCH AND SIGNAL PATH
- (a) Branch Construction method using frequency diversity
- (b) Branch Construction method using Time diversity
- COMBINING AND SWITCHNING METHODS
- Slide 29
- FOR COHERENT DETECTION
- (a) Maximal ratio combining (MRC)
- Slide 32
- (b) Equal Gain Combining (EGC)
- EGC
- For VHF UHF and microwave wireless radio applications
- (c) Selection or Switching Combining
- Slide 37
- Disadvantage of Selection or Switching
- Slide 39
- (a) Switching Methods with Fixed threshold
- Slide 41
- (b) Switching Methods with Variable threshold
- Slide 43
-
Introduction (contrsquod)
bull SpaceTransmission using multiple transmitreceive antennas
bull FrequencyTransmission using multiple frequency channels separated by at least the coherence bandwidth
bull Time Transmission using multiple time slots separated by at least the coherence time
Spatial diversity
bull Single-input single-output (SISO) channel
No spatial diversitybull Single-input multiple-output (SIMO) channel
Receive diversitybull Multiple-input single-output (MISO) channel
Transmit diversity bull Multiple-input multiple-output (MIMO) channel
Combined transmit and receive diversity
The following classes of diversity schemes can be identified
1Space diversity 2Polarization diversity 3Frequency diversity 4Time diversity 5Angle or direction diversity
1] Space diversity
bull The signal is transferred over several different propagation paths
bull In the case of wired transmission this can be achieved by transmitting via multiple wires
bull In the case of wireless transmission it can be achieved by antenna diversity using multiple transmitter antennas (transmit diversity) andor multiple receiving antennas (reception diversity)
bull In the latter case a diversity combining technique is applied before further signal processing takes place
2] Polarization diversity
bull Polarization diversity Multiple versions of a signal are transmitted and received via antennas with different polarization
bull A diversity combining technique is applied on the receiver side
POLARIZER
3] Frequency diversity
bull Frequency diversity The signal is transferred using several frequency channels or spread over a wide spectrum that is affected by frequency-selective fading
bull Middle-late 20th century microwave radio relay lines often used several regular wideband radio channels and one protection channel for automatic use by any faded channel Later examples include OFDM modulation in combination with subcarrier interleaving and
forward error correction Spread spectrum for example frequency hopping or DS-CDMA
4] Time diversity
bull Time diversity Multiple versions of the same signal are transmitted at different time instants
Terrestrial microwave radio system with two antenna arrays configured for space-diversity
Diversity Combining
bull Once you have created two or morediversity channels what do you do with them
Spatial diversity (contrsquod)
bullMaximum ratio combining (MRC)
h1
h2
h1
h2
yx
Combining schemes
bullSelection combining (SC)
h1
h2
yx
MonitorSNR
Selectbranch
Switch-and-stay combining (SSC) Switch-and-examine combining (SEC)
h1
h2
x
ComparatorChannelestimator
switchingthreshold
bullSwitched diversity
No trade off to
Without excessively increasing
bull 1 transmitting powerbull 2 Co-channel reuse distance
bull One of the most effective technique to solve this issue is diversity reception technique
What are all the needs of diversity techniques
bull 1No of signal transmission pathsbull 2A circuit to combine the received signal or
select one of them
CONCEPTS OF DIVERSITY BRANCH AND SIGNAL PATH
(a) Branch Construction method using frequency diversity
(b) Branch Construction method using Time diversity
COMBINING AND SWITCHNING METHODS
COMBINING AND SWITCHNINGMETHODS
FOR COHERENT DETECTION
FOR NON - COHERENT DETECTION
FOR COHERENT DETECTION
bull There is no difference whether the combining is carried out in the pre detection or in the post detection stage
FOR NON-COHERENT DETECTION
bull There is a difference in performance exists between whether pre detection amp post detection combining methods
(a) Maximal ratio combining (MRC)
bull MRC is the best performance improvement compared with the other methods
bull However the trade off is It requires 1 cophasing 2 weighting 3summing circuitsResulting in most complicated implementationComplexity performance
(b) Equal Gain Combining (EGC)
EGCbull EGC is similar to MRC except the weighting
circuits are omittedbull The performance improvement obtained by
equal gain combiner is slightly inferior to that of a MRC since the interference and noise corrupted signal combined with high quality signals
For VHF UHF and microwave wireless radio applications
bull Both MRC and EGC methods are unsuitablebull Compared with MRC EGC methods the
selection method is more suitable for mobile radio applications because of its simple implementation
(c) Selection or Switching Combining
bull The diversity branch having the highest signal level (or) lowest Pe is selected
bull Also in addition stable operation is easily achieved even in the fast multipath fading environments
bull But the performance improvement obtained by the selection method is still only slightly inferior to that of MRC method
Disadvantage of Selection or Switching
bull Combining The continuous monitoring of the signals requires the same no of receivers as the no of diversity branches
bull This redundancy can be alleviated by the use of switching or scanning receiver
SWITCHNINGMETHODS
FIXED THERSHOLD VARIABLE THERSHOLD
(a) Switching Methods with Fixed threshold
bull The switching from one branch to the other occurs when the signal level falls below a threshold value
bull The threshold value is fixedbull However this threshold value is not
necessarily the best over the entire service area
FIXED THERSHOLD
(b) Switching Methods with Variable threshold
bull Here the threshold value is adjusted dynamically as the vehicle moves
bull It includes the feedback using Estimationbull But it may introduce the envelope and phase
transients that will reduce the performance improvement
VARIABLE THERSHOLD
Conclusions
bull The diversity is used to provide the receiver with several replicas of the same signal
bull Diversity techniques are used to improve the performance of the radio channel without any increase in the transmitted power
bull As higher as the received signal replicas are decorrelated as much as the diversity gain
Thank you for you attention
- No trade off to
- What are all the needs of diversity techniques
- CONCEPTS OF DIVERSITY BRANCH AND SIGNAL PATH
- (a) Branch Construction method using frequency diversity
- (b) Branch Construction method using Time diversity
- COMBINING AND SWITCHNING METHODS
- Slide 29
- FOR COHERENT DETECTION
- (a) Maximal ratio combining (MRC)
- Slide 32
- (b) Equal Gain Combining (EGC)
- EGC
- For VHF UHF and microwave wireless radio applications
- (c) Selection or Switching Combining
- Slide 37
- Disadvantage of Selection or Switching
- Slide 39
- (a) Switching Methods with Fixed threshold
- Slide 41
- (b) Switching Methods with Variable threshold
- Slide 43
-
Spatial diversity
bull Single-input single-output (SISO) channel
No spatial diversitybull Single-input multiple-output (SIMO) channel
Receive diversitybull Multiple-input single-output (MISO) channel
Transmit diversity bull Multiple-input multiple-output (MIMO) channel
Combined transmit and receive diversity
The following classes of diversity schemes can be identified
1Space diversity 2Polarization diversity 3Frequency diversity 4Time diversity 5Angle or direction diversity
1] Space diversity
bull The signal is transferred over several different propagation paths
bull In the case of wired transmission this can be achieved by transmitting via multiple wires
bull In the case of wireless transmission it can be achieved by antenna diversity using multiple transmitter antennas (transmit diversity) andor multiple receiving antennas (reception diversity)
bull In the latter case a diversity combining technique is applied before further signal processing takes place
2] Polarization diversity
bull Polarization diversity Multiple versions of a signal are transmitted and received via antennas with different polarization
bull A diversity combining technique is applied on the receiver side
POLARIZER
3] Frequency diversity
bull Frequency diversity The signal is transferred using several frequency channels or spread over a wide spectrum that is affected by frequency-selective fading
bull Middle-late 20th century microwave radio relay lines often used several regular wideband radio channels and one protection channel for automatic use by any faded channel Later examples include OFDM modulation in combination with subcarrier interleaving and
forward error correction Spread spectrum for example frequency hopping or DS-CDMA
4] Time diversity
bull Time diversity Multiple versions of the same signal are transmitted at different time instants
Terrestrial microwave radio system with two antenna arrays configured for space-diversity
Diversity Combining
bull Once you have created two or morediversity channels what do you do with them
Spatial diversity (contrsquod)
bullMaximum ratio combining (MRC)
h1
h2
h1
h2
yx
Combining schemes
bullSelection combining (SC)
h1
h2
yx
MonitorSNR
Selectbranch
Switch-and-stay combining (SSC) Switch-and-examine combining (SEC)
h1
h2
x
ComparatorChannelestimator
switchingthreshold
bullSwitched diversity
No trade off to
Without excessively increasing
bull 1 transmitting powerbull 2 Co-channel reuse distance
bull One of the most effective technique to solve this issue is diversity reception technique
What are all the needs of diversity techniques
bull 1No of signal transmission pathsbull 2A circuit to combine the received signal or
select one of them
CONCEPTS OF DIVERSITY BRANCH AND SIGNAL PATH
(a) Branch Construction method using frequency diversity
(b) Branch Construction method using Time diversity
COMBINING AND SWITCHNING METHODS
COMBINING AND SWITCHNINGMETHODS
FOR COHERENT DETECTION
FOR NON - COHERENT DETECTION
FOR COHERENT DETECTION
bull There is no difference whether the combining is carried out in the pre detection or in the post detection stage
FOR NON-COHERENT DETECTION
bull There is a difference in performance exists between whether pre detection amp post detection combining methods
(a) Maximal ratio combining (MRC)
bull MRC is the best performance improvement compared with the other methods
bull However the trade off is It requires 1 cophasing 2 weighting 3summing circuitsResulting in most complicated implementationComplexity performance
(b) Equal Gain Combining (EGC)
EGCbull EGC is similar to MRC except the weighting
circuits are omittedbull The performance improvement obtained by
equal gain combiner is slightly inferior to that of a MRC since the interference and noise corrupted signal combined with high quality signals
For VHF UHF and microwave wireless radio applications
bull Both MRC and EGC methods are unsuitablebull Compared with MRC EGC methods the
selection method is more suitable for mobile radio applications because of its simple implementation
(c) Selection or Switching Combining
bull The diversity branch having the highest signal level (or) lowest Pe is selected
bull Also in addition stable operation is easily achieved even in the fast multipath fading environments
bull But the performance improvement obtained by the selection method is still only slightly inferior to that of MRC method
Disadvantage of Selection or Switching
bull Combining The continuous monitoring of the signals requires the same no of receivers as the no of diversity branches
bull This redundancy can be alleviated by the use of switching or scanning receiver
SWITCHNINGMETHODS
FIXED THERSHOLD VARIABLE THERSHOLD
(a) Switching Methods with Fixed threshold
bull The switching from one branch to the other occurs when the signal level falls below a threshold value
bull The threshold value is fixedbull However this threshold value is not
necessarily the best over the entire service area
FIXED THERSHOLD
(b) Switching Methods with Variable threshold
bull Here the threshold value is adjusted dynamically as the vehicle moves
bull It includes the feedback using Estimationbull But it may introduce the envelope and phase
transients that will reduce the performance improvement
VARIABLE THERSHOLD
Conclusions
bull The diversity is used to provide the receiver with several replicas of the same signal
bull Diversity techniques are used to improve the performance of the radio channel without any increase in the transmitted power
bull As higher as the received signal replicas are decorrelated as much as the diversity gain
Thank you for you attention
- No trade off to
- What are all the needs of diversity techniques
- CONCEPTS OF DIVERSITY BRANCH AND SIGNAL PATH
- (a) Branch Construction method using frequency diversity
- (b) Branch Construction method using Time diversity
- COMBINING AND SWITCHNING METHODS
- Slide 29
- FOR COHERENT DETECTION
- (a) Maximal ratio combining (MRC)
- Slide 32
- (b) Equal Gain Combining (EGC)
- EGC
- For VHF UHF and microwave wireless radio applications
- (c) Selection or Switching Combining
- Slide 37
- Disadvantage of Selection or Switching
- Slide 39
- (a) Switching Methods with Fixed threshold
- Slide 41
- (b) Switching Methods with Variable threshold
- Slide 43
-
The following classes of diversity schemes can be identified
1Space diversity 2Polarization diversity 3Frequency diversity 4Time diversity 5Angle or direction diversity
1] Space diversity
bull The signal is transferred over several different propagation paths
bull In the case of wired transmission this can be achieved by transmitting via multiple wires
bull In the case of wireless transmission it can be achieved by antenna diversity using multiple transmitter antennas (transmit diversity) andor multiple receiving antennas (reception diversity)
bull In the latter case a diversity combining technique is applied before further signal processing takes place
2] Polarization diversity
bull Polarization diversity Multiple versions of a signal are transmitted and received via antennas with different polarization
bull A diversity combining technique is applied on the receiver side
POLARIZER
3] Frequency diversity
bull Frequency diversity The signal is transferred using several frequency channels or spread over a wide spectrum that is affected by frequency-selective fading
bull Middle-late 20th century microwave radio relay lines often used several regular wideband radio channels and one protection channel for automatic use by any faded channel Later examples include OFDM modulation in combination with subcarrier interleaving and
forward error correction Spread spectrum for example frequency hopping or DS-CDMA
4] Time diversity
bull Time diversity Multiple versions of the same signal are transmitted at different time instants
Terrestrial microwave radio system with two antenna arrays configured for space-diversity
Diversity Combining
bull Once you have created two or morediversity channels what do you do with them
Spatial diversity (contrsquod)
bullMaximum ratio combining (MRC)
h1
h2
h1
h2
yx
Combining schemes
bullSelection combining (SC)
h1
h2
yx
MonitorSNR
Selectbranch
Switch-and-stay combining (SSC) Switch-and-examine combining (SEC)
h1
h2
x
ComparatorChannelestimator
switchingthreshold
bullSwitched diversity
No trade off to
Without excessively increasing
bull 1 transmitting powerbull 2 Co-channel reuse distance
bull One of the most effective technique to solve this issue is diversity reception technique
What are all the needs of diversity techniques
bull 1No of signal transmission pathsbull 2A circuit to combine the received signal or
select one of them
CONCEPTS OF DIVERSITY BRANCH AND SIGNAL PATH
(a) Branch Construction method using frequency diversity
(b) Branch Construction method using Time diversity
COMBINING AND SWITCHNING METHODS
COMBINING AND SWITCHNINGMETHODS
FOR COHERENT DETECTION
FOR NON - COHERENT DETECTION
FOR COHERENT DETECTION
bull There is no difference whether the combining is carried out in the pre detection or in the post detection stage
FOR NON-COHERENT DETECTION
bull There is a difference in performance exists between whether pre detection amp post detection combining methods
(a) Maximal ratio combining (MRC)
bull MRC is the best performance improvement compared with the other methods
bull However the trade off is It requires 1 cophasing 2 weighting 3summing circuitsResulting in most complicated implementationComplexity performance
(b) Equal Gain Combining (EGC)
EGCbull EGC is similar to MRC except the weighting
circuits are omittedbull The performance improvement obtained by
equal gain combiner is slightly inferior to that of a MRC since the interference and noise corrupted signal combined with high quality signals
For VHF UHF and microwave wireless radio applications
bull Both MRC and EGC methods are unsuitablebull Compared with MRC EGC methods the
selection method is more suitable for mobile radio applications because of its simple implementation
(c) Selection or Switching Combining
bull The diversity branch having the highest signal level (or) lowest Pe is selected
bull Also in addition stable operation is easily achieved even in the fast multipath fading environments
bull But the performance improvement obtained by the selection method is still only slightly inferior to that of MRC method
Disadvantage of Selection or Switching
bull Combining The continuous monitoring of the signals requires the same no of receivers as the no of diversity branches
bull This redundancy can be alleviated by the use of switching or scanning receiver
SWITCHNINGMETHODS
FIXED THERSHOLD VARIABLE THERSHOLD
(a) Switching Methods with Fixed threshold
bull The switching from one branch to the other occurs when the signal level falls below a threshold value
bull The threshold value is fixedbull However this threshold value is not
necessarily the best over the entire service area
FIXED THERSHOLD
(b) Switching Methods with Variable threshold
bull Here the threshold value is adjusted dynamically as the vehicle moves
bull It includes the feedback using Estimationbull But it may introduce the envelope and phase
transients that will reduce the performance improvement
VARIABLE THERSHOLD
Conclusions
bull The diversity is used to provide the receiver with several replicas of the same signal
bull Diversity techniques are used to improve the performance of the radio channel without any increase in the transmitted power
bull As higher as the received signal replicas are decorrelated as much as the diversity gain
Thank you for you attention
- No trade off to
- What are all the needs of diversity techniques
- CONCEPTS OF DIVERSITY BRANCH AND SIGNAL PATH
- (a) Branch Construction method using frequency diversity
- (b) Branch Construction method using Time diversity
- COMBINING AND SWITCHNING METHODS
- Slide 29
- FOR COHERENT DETECTION
- (a) Maximal ratio combining (MRC)
- Slide 32
- (b) Equal Gain Combining (EGC)
- EGC
- For VHF UHF and microwave wireless radio applications
- (c) Selection or Switching Combining
- Slide 37
- Disadvantage of Selection or Switching
- Slide 39
- (a) Switching Methods with Fixed threshold
- Slide 41
- (b) Switching Methods with Variable threshold
- Slide 43
-
1] Space diversity
bull The signal is transferred over several different propagation paths
bull In the case of wired transmission this can be achieved by transmitting via multiple wires
bull In the case of wireless transmission it can be achieved by antenna diversity using multiple transmitter antennas (transmit diversity) andor multiple receiving antennas (reception diversity)
bull In the latter case a diversity combining technique is applied before further signal processing takes place
2] Polarization diversity
bull Polarization diversity Multiple versions of a signal are transmitted and received via antennas with different polarization
bull A diversity combining technique is applied on the receiver side
POLARIZER
3] Frequency diversity
bull Frequency diversity The signal is transferred using several frequency channels or spread over a wide spectrum that is affected by frequency-selective fading
bull Middle-late 20th century microwave radio relay lines often used several regular wideband radio channels and one protection channel for automatic use by any faded channel Later examples include OFDM modulation in combination with subcarrier interleaving and
forward error correction Spread spectrum for example frequency hopping or DS-CDMA
4] Time diversity
bull Time diversity Multiple versions of the same signal are transmitted at different time instants
Terrestrial microwave radio system with two antenna arrays configured for space-diversity
Diversity Combining
bull Once you have created two or morediversity channels what do you do with them
Spatial diversity (contrsquod)
bullMaximum ratio combining (MRC)
h1
h2
h1
h2
yx
Combining schemes
bullSelection combining (SC)
h1
h2
yx
MonitorSNR
Selectbranch
Switch-and-stay combining (SSC) Switch-and-examine combining (SEC)
h1
h2
x
ComparatorChannelestimator
switchingthreshold
bullSwitched diversity
No trade off to
Without excessively increasing
bull 1 transmitting powerbull 2 Co-channel reuse distance
bull One of the most effective technique to solve this issue is diversity reception technique
What are all the needs of diversity techniques
bull 1No of signal transmission pathsbull 2A circuit to combine the received signal or
select one of them
CONCEPTS OF DIVERSITY BRANCH AND SIGNAL PATH
(a) Branch Construction method using frequency diversity
(b) Branch Construction method using Time diversity
COMBINING AND SWITCHNING METHODS
COMBINING AND SWITCHNINGMETHODS
FOR COHERENT DETECTION
FOR NON - COHERENT DETECTION
FOR COHERENT DETECTION
bull There is no difference whether the combining is carried out in the pre detection or in the post detection stage
FOR NON-COHERENT DETECTION
bull There is a difference in performance exists between whether pre detection amp post detection combining methods
(a) Maximal ratio combining (MRC)
bull MRC is the best performance improvement compared with the other methods
bull However the trade off is It requires 1 cophasing 2 weighting 3summing circuitsResulting in most complicated implementationComplexity performance
(b) Equal Gain Combining (EGC)
EGCbull EGC is similar to MRC except the weighting
circuits are omittedbull The performance improvement obtained by
equal gain combiner is slightly inferior to that of a MRC since the interference and noise corrupted signal combined with high quality signals
For VHF UHF and microwave wireless radio applications
bull Both MRC and EGC methods are unsuitablebull Compared with MRC EGC methods the
selection method is more suitable for mobile radio applications because of its simple implementation
(c) Selection or Switching Combining
bull The diversity branch having the highest signal level (or) lowest Pe is selected
bull Also in addition stable operation is easily achieved even in the fast multipath fading environments
bull But the performance improvement obtained by the selection method is still only slightly inferior to that of MRC method
Disadvantage of Selection or Switching
bull Combining The continuous monitoring of the signals requires the same no of receivers as the no of diversity branches
bull This redundancy can be alleviated by the use of switching or scanning receiver
SWITCHNINGMETHODS
FIXED THERSHOLD VARIABLE THERSHOLD
(a) Switching Methods with Fixed threshold
bull The switching from one branch to the other occurs when the signal level falls below a threshold value
bull The threshold value is fixedbull However this threshold value is not
necessarily the best over the entire service area
FIXED THERSHOLD
(b) Switching Methods with Variable threshold
bull Here the threshold value is adjusted dynamically as the vehicle moves
bull It includes the feedback using Estimationbull But it may introduce the envelope and phase
transients that will reduce the performance improvement
VARIABLE THERSHOLD
Conclusions
bull The diversity is used to provide the receiver with several replicas of the same signal
bull Diversity techniques are used to improve the performance of the radio channel without any increase in the transmitted power
bull As higher as the received signal replicas are decorrelated as much as the diversity gain
Thank you for you attention
- No trade off to
- What are all the needs of diversity techniques
- CONCEPTS OF DIVERSITY BRANCH AND SIGNAL PATH
- (a) Branch Construction method using frequency diversity
- (b) Branch Construction method using Time diversity
- COMBINING AND SWITCHNING METHODS
- Slide 29
- FOR COHERENT DETECTION
- (a) Maximal ratio combining (MRC)
- Slide 32
- (b) Equal Gain Combining (EGC)
- EGC
- For VHF UHF and microwave wireless radio applications
- (c) Selection or Switching Combining
- Slide 37
- Disadvantage of Selection or Switching
- Slide 39
- (a) Switching Methods with Fixed threshold
- Slide 41
- (b) Switching Methods with Variable threshold
- Slide 43
-
2] Polarization diversity
bull Polarization diversity Multiple versions of a signal are transmitted and received via antennas with different polarization
bull A diversity combining technique is applied on the receiver side
POLARIZER
3] Frequency diversity
bull Frequency diversity The signal is transferred using several frequency channels or spread over a wide spectrum that is affected by frequency-selective fading
bull Middle-late 20th century microwave radio relay lines often used several regular wideband radio channels and one protection channel for automatic use by any faded channel Later examples include OFDM modulation in combination with subcarrier interleaving and
forward error correction Spread spectrum for example frequency hopping or DS-CDMA
4] Time diversity
bull Time diversity Multiple versions of the same signal are transmitted at different time instants
Terrestrial microwave radio system with two antenna arrays configured for space-diversity
Diversity Combining
bull Once you have created two or morediversity channels what do you do with them
Spatial diversity (contrsquod)
bullMaximum ratio combining (MRC)
h1
h2
h1
h2
yx
Combining schemes
bullSelection combining (SC)
h1
h2
yx
MonitorSNR
Selectbranch
Switch-and-stay combining (SSC) Switch-and-examine combining (SEC)
h1
h2
x
ComparatorChannelestimator
switchingthreshold
bullSwitched diversity
No trade off to
Without excessively increasing
bull 1 transmitting powerbull 2 Co-channel reuse distance
bull One of the most effective technique to solve this issue is diversity reception technique
What are all the needs of diversity techniques
bull 1No of signal transmission pathsbull 2A circuit to combine the received signal or
select one of them
CONCEPTS OF DIVERSITY BRANCH AND SIGNAL PATH
(a) Branch Construction method using frequency diversity
(b) Branch Construction method using Time diversity
COMBINING AND SWITCHNING METHODS
COMBINING AND SWITCHNINGMETHODS
FOR COHERENT DETECTION
FOR NON - COHERENT DETECTION
FOR COHERENT DETECTION
bull There is no difference whether the combining is carried out in the pre detection or in the post detection stage
FOR NON-COHERENT DETECTION
bull There is a difference in performance exists between whether pre detection amp post detection combining methods
(a) Maximal ratio combining (MRC)
bull MRC is the best performance improvement compared with the other methods
bull However the trade off is It requires 1 cophasing 2 weighting 3summing circuitsResulting in most complicated implementationComplexity performance
(b) Equal Gain Combining (EGC)
EGCbull EGC is similar to MRC except the weighting
circuits are omittedbull The performance improvement obtained by
equal gain combiner is slightly inferior to that of a MRC since the interference and noise corrupted signal combined with high quality signals
For VHF UHF and microwave wireless radio applications
bull Both MRC and EGC methods are unsuitablebull Compared with MRC EGC methods the
selection method is more suitable for mobile radio applications because of its simple implementation
(c) Selection or Switching Combining
bull The diversity branch having the highest signal level (or) lowest Pe is selected
bull Also in addition stable operation is easily achieved even in the fast multipath fading environments
bull But the performance improvement obtained by the selection method is still only slightly inferior to that of MRC method
Disadvantage of Selection or Switching
bull Combining The continuous monitoring of the signals requires the same no of receivers as the no of diversity branches
bull This redundancy can be alleviated by the use of switching or scanning receiver
SWITCHNINGMETHODS
FIXED THERSHOLD VARIABLE THERSHOLD
(a) Switching Methods with Fixed threshold
bull The switching from one branch to the other occurs when the signal level falls below a threshold value
bull The threshold value is fixedbull However this threshold value is not
necessarily the best over the entire service area
FIXED THERSHOLD
(b) Switching Methods with Variable threshold
bull Here the threshold value is adjusted dynamically as the vehicle moves
bull It includes the feedback using Estimationbull But it may introduce the envelope and phase
transients that will reduce the performance improvement
VARIABLE THERSHOLD
Conclusions
bull The diversity is used to provide the receiver with several replicas of the same signal
bull Diversity techniques are used to improve the performance of the radio channel without any increase in the transmitted power
bull As higher as the received signal replicas are decorrelated as much as the diversity gain
Thank you for you attention
- No trade off to
- What are all the needs of diversity techniques
- CONCEPTS OF DIVERSITY BRANCH AND SIGNAL PATH
- (a) Branch Construction method using frequency diversity
- (b) Branch Construction method using Time diversity
- COMBINING AND SWITCHNING METHODS
- Slide 29
- FOR COHERENT DETECTION
- (a) Maximal ratio combining (MRC)
- Slide 32
- (b) Equal Gain Combining (EGC)
- EGC
- For VHF UHF and microwave wireless radio applications
- (c) Selection or Switching Combining
- Slide 37
- Disadvantage of Selection or Switching
- Slide 39
- (a) Switching Methods with Fixed threshold
- Slide 41
- (b) Switching Methods with Variable threshold
- Slide 43
-
POLARIZER
3] Frequency diversity
bull Frequency diversity The signal is transferred using several frequency channels or spread over a wide spectrum that is affected by frequency-selective fading
bull Middle-late 20th century microwave radio relay lines often used several regular wideband radio channels and one protection channel for automatic use by any faded channel Later examples include OFDM modulation in combination with subcarrier interleaving and
forward error correction Spread spectrum for example frequency hopping or DS-CDMA
4] Time diversity
bull Time diversity Multiple versions of the same signal are transmitted at different time instants
Terrestrial microwave radio system with two antenna arrays configured for space-diversity
Diversity Combining
bull Once you have created two or morediversity channels what do you do with them
Spatial diversity (contrsquod)
bullMaximum ratio combining (MRC)
h1
h2
h1
h2
yx
Combining schemes
bullSelection combining (SC)
h1
h2
yx
MonitorSNR
Selectbranch
Switch-and-stay combining (SSC) Switch-and-examine combining (SEC)
h1
h2
x
ComparatorChannelestimator
switchingthreshold
bullSwitched diversity
No trade off to
Without excessively increasing
bull 1 transmitting powerbull 2 Co-channel reuse distance
bull One of the most effective technique to solve this issue is diversity reception technique
What are all the needs of diversity techniques
bull 1No of signal transmission pathsbull 2A circuit to combine the received signal or
select one of them
CONCEPTS OF DIVERSITY BRANCH AND SIGNAL PATH
(a) Branch Construction method using frequency diversity
(b) Branch Construction method using Time diversity
COMBINING AND SWITCHNING METHODS
COMBINING AND SWITCHNINGMETHODS
FOR COHERENT DETECTION
FOR NON - COHERENT DETECTION
FOR COHERENT DETECTION
bull There is no difference whether the combining is carried out in the pre detection or in the post detection stage
FOR NON-COHERENT DETECTION
bull There is a difference in performance exists between whether pre detection amp post detection combining methods
(a) Maximal ratio combining (MRC)
bull MRC is the best performance improvement compared with the other methods
bull However the trade off is It requires 1 cophasing 2 weighting 3summing circuitsResulting in most complicated implementationComplexity performance
(b) Equal Gain Combining (EGC)
EGCbull EGC is similar to MRC except the weighting
circuits are omittedbull The performance improvement obtained by
equal gain combiner is slightly inferior to that of a MRC since the interference and noise corrupted signal combined with high quality signals
For VHF UHF and microwave wireless radio applications
bull Both MRC and EGC methods are unsuitablebull Compared with MRC EGC methods the
selection method is more suitable for mobile radio applications because of its simple implementation
(c) Selection or Switching Combining
bull The diversity branch having the highest signal level (or) lowest Pe is selected
bull Also in addition stable operation is easily achieved even in the fast multipath fading environments
bull But the performance improvement obtained by the selection method is still only slightly inferior to that of MRC method
Disadvantage of Selection or Switching
bull Combining The continuous monitoring of the signals requires the same no of receivers as the no of diversity branches
bull This redundancy can be alleviated by the use of switching or scanning receiver
SWITCHNINGMETHODS
FIXED THERSHOLD VARIABLE THERSHOLD
(a) Switching Methods with Fixed threshold
bull The switching from one branch to the other occurs when the signal level falls below a threshold value
bull The threshold value is fixedbull However this threshold value is not
necessarily the best over the entire service area
FIXED THERSHOLD
(b) Switching Methods with Variable threshold
bull Here the threshold value is adjusted dynamically as the vehicle moves
bull It includes the feedback using Estimationbull But it may introduce the envelope and phase
transients that will reduce the performance improvement
VARIABLE THERSHOLD
Conclusions
bull The diversity is used to provide the receiver with several replicas of the same signal
bull Diversity techniques are used to improve the performance of the radio channel without any increase in the transmitted power
bull As higher as the received signal replicas are decorrelated as much as the diversity gain
Thank you for you attention
- No trade off to
- What are all the needs of diversity techniques
- CONCEPTS OF DIVERSITY BRANCH AND SIGNAL PATH
- (a) Branch Construction method using frequency diversity
- (b) Branch Construction method using Time diversity
- COMBINING AND SWITCHNING METHODS
- Slide 29
- FOR COHERENT DETECTION
- (a) Maximal ratio combining (MRC)
- Slide 32
- (b) Equal Gain Combining (EGC)
- EGC
- For VHF UHF and microwave wireless radio applications
- (c) Selection or Switching Combining
- Slide 37
- Disadvantage of Selection or Switching
- Slide 39
- (a) Switching Methods with Fixed threshold
- Slide 41
- (b) Switching Methods with Variable threshold
- Slide 43
-
3] Frequency diversity
bull Frequency diversity The signal is transferred using several frequency channels or spread over a wide spectrum that is affected by frequency-selective fading
bull Middle-late 20th century microwave radio relay lines often used several regular wideband radio channels and one protection channel for automatic use by any faded channel Later examples include OFDM modulation in combination with subcarrier interleaving and
forward error correction Spread spectrum for example frequency hopping or DS-CDMA
4] Time diversity
bull Time diversity Multiple versions of the same signal are transmitted at different time instants
Terrestrial microwave radio system with two antenna arrays configured for space-diversity
Diversity Combining
bull Once you have created two or morediversity channels what do you do with them
Spatial diversity (contrsquod)
bullMaximum ratio combining (MRC)
h1
h2
h1
h2
yx
Combining schemes
bullSelection combining (SC)
h1
h2
yx
MonitorSNR
Selectbranch
Switch-and-stay combining (SSC) Switch-and-examine combining (SEC)
h1
h2
x
ComparatorChannelestimator
switchingthreshold
bullSwitched diversity
No trade off to
Without excessively increasing
bull 1 transmitting powerbull 2 Co-channel reuse distance
bull One of the most effective technique to solve this issue is diversity reception technique
What are all the needs of diversity techniques
bull 1No of signal transmission pathsbull 2A circuit to combine the received signal or
select one of them
CONCEPTS OF DIVERSITY BRANCH AND SIGNAL PATH
(a) Branch Construction method using frequency diversity
(b) Branch Construction method using Time diversity
COMBINING AND SWITCHNING METHODS
COMBINING AND SWITCHNINGMETHODS
FOR COHERENT DETECTION
FOR NON - COHERENT DETECTION
FOR COHERENT DETECTION
bull There is no difference whether the combining is carried out in the pre detection or in the post detection stage
FOR NON-COHERENT DETECTION
bull There is a difference in performance exists between whether pre detection amp post detection combining methods
(a) Maximal ratio combining (MRC)
bull MRC is the best performance improvement compared with the other methods
bull However the trade off is It requires 1 cophasing 2 weighting 3summing circuitsResulting in most complicated implementationComplexity performance
(b) Equal Gain Combining (EGC)
EGCbull EGC is similar to MRC except the weighting
circuits are omittedbull The performance improvement obtained by
equal gain combiner is slightly inferior to that of a MRC since the interference and noise corrupted signal combined with high quality signals
For VHF UHF and microwave wireless radio applications
bull Both MRC and EGC methods are unsuitablebull Compared with MRC EGC methods the
selection method is more suitable for mobile radio applications because of its simple implementation
(c) Selection or Switching Combining
bull The diversity branch having the highest signal level (or) lowest Pe is selected
bull Also in addition stable operation is easily achieved even in the fast multipath fading environments
bull But the performance improvement obtained by the selection method is still only slightly inferior to that of MRC method
Disadvantage of Selection or Switching
bull Combining The continuous monitoring of the signals requires the same no of receivers as the no of diversity branches
bull This redundancy can be alleviated by the use of switching or scanning receiver
SWITCHNINGMETHODS
FIXED THERSHOLD VARIABLE THERSHOLD
(a) Switching Methods with Fixed threshold
bull The switching from one branch to the other occurs when the signal level falls below a threshold value
bull The threshold value is fixedbull However this threshold value is not
necessarily the best over the entire service area
FIXED THERSHOLD
(b) Switching Methods with Variable threshold
bull Here the threshold value is adjusted dynamically as the vehicle moves
bull It includes the feedback using Estimationbull But it may introduce the envelope and phase
transients that will reduce the performance improvement
VARIABLE THERSHOLD
Conclusions
bull The diversity is used to provide the receiver with several replicas of the same signal
bull Diversity techniques are used to improve the performance of the radio channel without any increase in the transmitted power
bull As higher as the received signal replicas are decorrelated as much as the diversity gain
Thank you for you attention
- No trade off to
- What are all the needs of diversity techniques
- CONCEPTS OF DIVERSITY BRANCH AND SIGNAL PATH
- (a) Branch Construction method using frequency diversity
- (b) Branch Construction method using Time diversity
- COMBINING AND SWITCHNING METHODS
- Slide 29
- FOR COHERENT DETECTION
- (a) Maximal ratio combining (MRC)
- Slide 32
- (b) Equal Gain Combining (EGC)
- EGC
- For VHF UHF and microwave wireless radio applications
- (c) Selection or Switching Combining
- Slide 37
- Disadvantage of Selection or Switching
- Slide 39
- (a) Switching Methods with Fixed threshold
- Slide 41
- (b) Switching Methods with Variable threshold
- Slide 43
-
4] Time diversity
bull Time diversity Multiple versions of the same signal are transmitted at different time instants
Terrestrial microwave radio system with two antenna arrays configured for space-diversity
Diversity Combining
bull Once you have created two or morediversity channels what do you do with them
Spatial diversity (contrsquod)
bullMaximum ratio combining (MRC)
h1
h2
h1
h2
yx
Combining schemes
bullSelection combining (SC)
h1
h2
yx
MonitorSNR
Selectbranch
Switch-and-stay combining (SSC) Switch-and-examine combining (SEC)
h1
h2
x
ComparatorChannelestimator
switchingthreshold
bullSwitched diversity
No trade off to
Without excessively increasing
bull 1 transmitting powerbull 2 Co-channel reuse distance
bull One of the most effective technique to solve this issue is diversity reception technique
What are all the needs of diversity techniques
bull 1No of signal transmission pathsbull 2A circuit to combine the received signal or
select one of them
CONCEPTS OF DIVERSITY BRANCH AND SIGNAL PATH
(a) Branch Construction method using frequency diversity
(b) Branch Construction method using Time diversity
COMBINING AND SWITCHNING METHODS
COMBINING AND SWITCHNINGMETHODS
FOR COHERENT DETECTION
FOR NON - COHERENT DETECTION
FOR COHERENT DETECTION
bull There is no difference whether the combining is carried out in the pre detection or in the post detection stage
FOR NON-COHERENT DETECTION
bull There is a difference in performance exists between whether pre detection amp post detection combining methods
(a) Maximal ratio combining (MRC)
bull MRC is the best performance improvement compared with the other methods
bull However the trade off is It requires 1 cophasing 2 weighting 3summing circuitsResulting in most complicated implementationComplexity performance
(b) Equal Gain Combining (EGC)
EGCbull EGC is similar to MRC except the weighting
circuits are omittedbull The performance improvement obtained by
equal gain combiner is slightly inferior to that of a MRC since the interference and noise corrupted signal combined with high quality signals
For VHF UHF and microwave wireless radio applications
bull Both MRC and EGC methods are unsuitablebull Compared with MRC EGC methods the
selection method is more suitable for mobile radio applications because of its simple implementation
(c) Selection or Switching Combining
bull The diversity branch having the highest signal level (or) lowest Pe is selected
bull Also in addition stable operation is easily achieved even in the fast multipath fading environments
bull But the performance improvement obtained by the selection method is still only slightly inferior to that of MRC method
Disadvantage of Selection or Switching
bull Combining The continuous monitoring of the signals requires the same no of receivers as the no of diversity branches
bull This redundancy can be alleviated by the use of switching or scanning receiver
SWITCHNINGMETHODS
FIXED THERSHOLD VARIABLE THERSHOLD
(a) Switching Methods with Fixed threshold
bull The switching from one branch to the other occurs when the signal level falls below a threshold value
bull The threshold value is fixedbull However this threshold value is not
necessarily the best over the entire service area
FIXED THERSHOLD
(b) Switching Methods with Variable threshold
bull Here the threshold value is adjusted dynamically as the vehicle moves
bull It includes the feedback using Estimationbull But it may introduce the envelope and phase
transients that will reduce the performance improvement
VARIABLE THERSHOLD
Conclusions
bull The diversity is used to provide the receiver with several replicas of the same signal
bull Diversity techniques are used to improve the performance of the radio channel without any increase in the transmitted power
bull As higher as the received signal replicas are decorrelated as much as the diversity gain
Thank you for you attention
- No trade off to
- What are all the needs of diversity techniques
- CONCEPTS OF DIVERSITY BRANCH AND SIGNAL PATH
- (a) Branch Construction method using frequency diversity
- (b) Branch Construction method using Time diversity
- COMBINING AND SWITCHNING METHODS
- Slide 29
- FOR COHERENT DETECTION
- (a) Maximal ratio combining (MRC)
- Slide 32
- (b) Equal Gain Combining (EGC)
- EGC
- For VHF UHF and microwave wireless radio applications
- (c) Selection or Switching Combining
- Slide 37
- Disadvantage of Selection or Switching
- Slide 39
- (a) Switching Methods with Fixed threshold
- Slide 41
- (b) Switching Methods with Variable threshold
- Slide 43
-
Terrestrial microwave radio system with two antenna arrays configured for space-diversity
Diversity Combining
bull Once you have created two or morediversity channels what do you do with them
Spatial diversity (contrsquod)
bullMaximum ratio combining (MRC)
h1
h2
h1
h2
yx
Combining schemes
bullSelection combining (SC)
h1
h2
yx
MonitorSNR
Selectbranch
Switch-and-stay combining (SSC) Switch-and-examine combining (SEC)
h1
h2
x
ComparatorChannelestimator
switchingthreshold
bullSwitched diversity
No trade off to
Without excessively increasing
bull 1 transmitting powerbull 2 Co-channel reuse distance
bull One of the most effective technique to solve this issue is diversity reception technique
What are all the needs of diversity techniques
bull 1No of signal transmission pathsbull 2A circuit to combine the received signal or
select one of them
CONCEPTS OF DIVERSITY BRANCH AND SIGNAL PATH
(a) Branch Construction method using frequency diversity
(b) Branch Construction method using Time diversity
COMBINING AND SWITCHNING METHODS
COMBINING AND SWITCHNINGMETHODS
FOR COHERENT DETECTION
FOR NON - COHERENT DETECTION
FOR COHERENT DETECTION
bull There is no difference whether the combining is carried out in the pre detection or in the post detection stage
FOR NON-COHERENT DETECTION
bull There is a difference in performance exists between whether pre detection amp post detection combining methods
(a) Maximal ratio combining (MRC)
bull MRC is the best performance improvement compared with the other methods
bull However the trade off is It requires 1 cophasing 2 weighting 3summing circuitsResulting in most complicated implementationComplexity performance
(b) Equal Gain Combining (EGC)
EGCbull EGC is similar to MRC except the weighting
circuits are omittedbull The performance improvement obtained by
equal gain combiner is slightly inferior to that of a MRC since the interference and noise corrupted signal combined with high quality signals
For VHF UHF and microwave wireless radio applications
bull Both MRC and EGC methods are unsuitablebull Compared with MRC EGC methods the
selection method is more suitable for mobile radio applications because of its simple implementation
(c) Selection or Switching Combining
bull The diversity branch having the highest signal level (or) lowest Pe is selected
bull Also in addition stable operation is easily achieved even in the fast multipath fading environments
bull But the performance improvement obtained by the selection method is still only slightly inferior to that of MRC method
Disadvantage of Selection or Switching
bull Combining The continuous monitoring of the signals requires the same no of receivers as the no of diversity branches
bull This redundancy can be alleviated by the use of switching or scanning receiver
SWITCHNINGMETHODS
FIXED THERSHOLD VARIABLE THERSHOLD
(a) Switching Methods with Fixed threshold
bull The switching from one branch to the other occurs when the signal level falls below a threshold value
bull The threshold value is fixedbull However this threshold value is not
necessarily the best over the entire service area
FIXED THERSHOLD
(b) Switching Methods with Variable threshold
bull Here the threshold value is adjusted dynamically as the vehicle moves
bull It includes the feedback using Estimationbull But it may introduce the envelope and phase
transients that will reduce the performance improvement
VARIABLE THERSHOLD
Conclusions
bull The diversity is used to provide the receiver with several replicas of the same signal
bull Diversity techniques are used to improve the performance of the radio channel without any increase in the transmitted power
bull As higher as the received signal replicas are decorrelated as much as the diversity gain
Thank you for you attention
- No trade off to
- What are all the needs of diversity techniques
- CONCEPTS OF DIVERSITY BRANCH AND SIGNAL PATH
- (a) Branch Construction method using frequency diversity
- (b) Branch Construction method using Time diversity
- COMBINING AND SWITCHNING METHODS
- Slide 29
- FOR COHERENT DETECTION
- (a) Maximal ratio combining (MRC)
- Slide 32
- (b) Equal Gain Combining (EGC)
- EGC
- For VHF UHF and microwave wireless radio applications
- (c) Selection or Switching Combining
- Slide 37
- Disadvantage of Selection or Switching
- Slide 39
- (a) Switching Methods with Fixed threshold
- Slide 41
- (b) Switching Methods with Variable threshold
- Slide 43
-
Diversity Combining
bull Once you have created two or morediversity channels what do you do with them
Spatial diversity (contrsquod)
bullMaximum ratio combining (MRC)
h1
h2
h1
h2
yx
Combining schemes
bullSelection combining (SC)
h1
h2
yx
MonitorSNR
Selectbranch
Switch-and-stay combining (SSC) Switch-and-examine combining (SEC)
h1
h2
x
ComparatorChannelestimator
switchingthreshold
bullSwitched diversity
No trade off to
Without excessively increasing
bull 1 transmitting powerbull 2 Co-channel reuse distance
bull One of the most effective technique to solve this issue is diversity reception technique
What are all the needs of diversity techniques
bull 1No of signal transmission pathsbull 2A circuit to combine the received signal or
select one of them
CONCEPTS OF DIVERSITY BRANCH AND SIGNAL PATH
(a) Branch Construction method using frequency diversity
(b) Branch Construction method using Time diversity
COMBINING AND SWITCHNING METHODS
COMBINING AND SWITCHNINGMETHODS
FOR COHERENT DETECTION
FOR NON - COHERENT DETECTION
FOR COHERENT DETECTION
bull There is no difference whether the combining is carried out in the pre detection or in the post detection stage
FOR NON-COHERENT DETECTION
bull There is a difference in performance exists between whether pre detection amp post detection combining methods
(a) Maximal ratio combining (MRC)
bull MRC is the best performance improvement compared with the other methods
bull However the trade off is It requires 1 cophasing 2 weighting 3summing circuitsResulting in most complicated implementationComplexity performance
(b) Equal Gain Combining (EGC)
EGCbull EGC is similar to MRC except the weighting
circuits are omittedbull The performance improvement obtained by
equal gain combiner is slightly inferior to that of a MRC since the interference and noise corrupted signal combined with high quality signals
For VHF UHF and microwave wireless radio applications
bull Both MRC and EGC methods are unsuitablebull Compared with MRC EGC methods the
selection method is more suitable for mobile radio applications because of its simple implementation
(c) Selection or Switching Combining
bull The diversity branch having the highest signal level (or) lowest Pe is selected
bull Also in addition stable operation is easily achieved even in the fast multipath fading environments
bull But the performance improvement obtained by the selection method is still only slightly inferior to that of MRC method
Disadvantage of Selection or Switching
bull Combining The continuous monitoring of the signals requires the same no of receivers as the no of diversity branches
bull This redundancy can be alleviated by the use of switching or scanning receiver
SWITCHNINGMETHODS
FIXED THERSHOLD VARIABLE THERSHOLD
(a) Switching Methods with Fixed threshold
bull The switching from one branch to the other occurs when the signal level falls below a threshold value
bull The threshold value is fixedbull However this threshold value is not
necessarily the best over the entire service area
FIXED THERSHOLD
(b) Switching Methods with Variable threshold
bull Here the threshold value is adjusted dynamically as the vehicle moves
bull It includes the feedback using Estimationbull But it may introduce the envelope and phase
transients that will reduce the performance improvement
VARIABLE THERSHOLD
Conclusions
bull The diversity is used to provide the receiver with several replicas of the same signal
bull Diversity techniques are used to improve the performance of the radio channel without any increase in the transmitted power
bull As higher as the received signal replicas are decorrelated as much as the diversity gain
Thank you for you attention
- No trade off to
- What are all the needs of diversity techniques
- CONCEPTS OF DIVERSITY BRANCH AND SIGNAL PATH
- (a) Branch Construction method using frequency diversity
- (b) Branch Construction method using Time diversity
- COMBINING AND SWITCHNING METHODS
- Slide 29
- FOR COHERENT DETECTION
- (a) Maximal ratio combining (MRC)
- Slide 32
- (b) Equal Gain Combining (EGC)
- EGC
- For VHF UHF and microwave wireless radio applications
- (c) Selection or Switching Combining
- Slide 37
- Disadvantage of Selection or Switching
- Slide 39
- (a) Switching Methods with Fixed threshold
- Slide 41
- (b) Switching Methods with Variable threshold
- Slide 43
-
Spatial diversity (contrsquod)
bullMaximum ratio combining (MRC)
h1
h2
h1
h2
yx
Combining schemes
bullSelection combining (SC)
h1
h2
yx
MonitorSNR
Selectbranch
Switch-and-stay combining (SSC) Switch-and-examine combining (SEC)
h1
h2
x
ComparatorChannelestimator
switchingthreshold
bullSwitched diversity
No trade off to
Without excessively increasing
bull 1 transmitting powerbull 2 Co-channel reuse distance
bull One of the most effective technique to solve this issue is diversity reception technique
What are all the needs of diversity techniques
bull 1No of signal transmission pathsbull 2A circuit to combine the received signal or
select one of them
CONCEPTS OF DIVERSITY BRANCH AND SIGNAL PATH
(a) Branch Construction method using frequency diversity
(b) Branch Construction method using Time diversity
COMBINING AND SWITCHNING METHODS
COMBINING AND SWITCHNINGMETHODS
FOR COHERENT DETECTION
FOR NON - COHERENT DETECTION
FOR COHERENT DETECTION
bull There is no difference whether the combining is carried out in the pre detection or in the post detection stage
FOR NON-COHERENT DETECTION
bull There is a difference in performance exists between whether pre detection amp post detection combining methods
(a) Maximal ratio combining (MRC)
bull MRC is the best performance improvement compared with the other methods
bull However the trade off is It requires 1 cophasing 2 weighting 3summing circuitsResulting in most complicated implementationComplexity performance
(b) Equal Gain Combining (EGC)
EGCbull EGC is similar to MRC except the weighting
circuits are omittedbull The performance improvement obtained by
equal gain combiner is slightly inferior to that of a MRC since the interference and noise corrupted signal combined with high quality signals
For VHF UHF and microwave wireless radio applications
bull Both MRC and EGC methods are unsuitablebull Compared with MRC EGC methods the
selection method is more suitable for mobile radio applications because of its simple implementation
(c) Selection or Switching Combining
bull The diversity branch having the highest signal level (or) lowest Pe is selected
bull Also in addition stable operation is easily achieved even in the fast multipath fading environments
bull But the performance improvement obtained by the selection method is still only slightly inferior to that of MRC method
Disadvantage of Selection or Switching
bull Combining The continuous monitoring of the signals requires the same no of receivers as the no of diversity branches
bull This redundancy can be alleviated by the use of switching or scanning receiver
SWITCHNINGMETHODS
FIXED THERSHOLD VARIABLE THERSHOLD
(a) Switching Methods with Fixed threshold
bull The switching from one branch to the other occurs when the signal level falls below a threshold value
bull The threshold value is fixedbull However this threshold value is not
necessarily the best over the entire service area
FIXED THERSHOLD
(b) Switching Methods with Variable threshold
bull Here the threshold value is adjusted dynamically as the vehicle moves
bull It includes the feedback using Estimationbull But it may introduce the envelope and phase
transients that will reduce the performance improvement
VARIABLE THERSHOLD
Conclusions
bull The diversity is used to provide the receiver with several replicas of the same signal
bull Diversity techniques are used to improve the performance of the radio channel without any increase in the transmitted power
bull As higher as the received signal replicas are decorrelated as much as the diversity gain
Thank you for you attention
- No trade off to
- What are all the needs of diversity techniques
- CONCEPTS OF DIVERSITY BRANCH AND SIGNAL PATH
- (a) Branch Construction method using frequency diversity
- (b) Branch Construction method using Time diversity
- COMBINING AND SWITCHNING METHODS
- Slide 29
- FOR COHERENT DETECTION
- (a) Maximal ratio combining (MRC)
- Slide 32
- (b) Equal Gain Combining (EGC)
- EGC
- For VHF UHF and microwave wireless radio applications
- (c) Selection or Switching Combining
- Slide 37
- Disadvantage of Selection or Switching
- Slide 39
- (a) Switching Methods with Fixed threshold
- Slide 41
- (b) Switching Methods with Variable threshold
- Slide 43
-
Combining schemes
bullSelection combining (SC)
h1
h2
yx
MonitorSNR
Selectbranch
Switch-and-stay combining (SSC) Switch-and-examine combining (SEC)
h1
h2
x
ComparatorChannelestimator
switchingthreshold
bullSwitched diversity
No trade off to
Without excessively increasing
bull 1 transmitting powerbull 2 Co-channel reuse distance
bull One of the most effective technique to solve this issue is diversity reception technique
What are all the needs of diversity techniques
bull 1No of signal transmission pathsbull 2A circuit to combine the received signal or
select one of them
CONCEPTS OF DIVERSITY BRANCH AND SIGNAL PATH
(a) Branch Construction method using frequency diversity
(b) Branch Construction method using Time diversity
COMBINING AND SWITCHNING METHODS
COMBINING AND SWITCHNINGMETHODS
FOR COHERENT DETECTION
FOR NON - COHERENT DETECTION
FOR COHERENT DETECTION
bull There is no difference whether the combining is carried out in the pre detection or in the post detection stage
FOR NON-COHERENT DETECTION
bull There is a difference in performance exists between whether pre detection amp post detection combining methods
(a) Maximal ratio combining (MRC)
bull MRC is the best performance improvement compared with the other methods
bull However the trade off is It requires 1 cophasing 2 weighting 3summing circuitsResulting in most complicated implementationComplexity performance
(b) Equal Gain Combining (EGC)
EGCbull EGC is similar to MRC except the weighting
circuits are omittedbull The performance improvement obtained by
equal gain combiner is slightly inferior to that of a MRC since the interference and noise corrupted signal combined with high quality signals
For VHF UHF and microwave wireless radio applications
bull Both MRC and EGC methods are unsuitablebull Compared with MRC EGC methods the
selection method is more suitable for mobile radio applications because of its simple implementation
(c) Selection or Switching Combining
bull The diversity branch having the highest signal level (or) lowest Pe is selected
bull Also in addition stable operation is easily achieved even in the fast multipath fading environments
bull But the performance improvement obtained by the selection method is still only slightly inferior to that of MRC method
Disadvantage of Selection or Switching
bull Combining The continuous monitoring of the signals requires the same no of receivers as the no of diversity branches
bull This redundancy can be alleviated by the use of switching or scanning receiver
SWITCHNINGMETHODS
FIXED THERSHOLD VARIABLE THERSHOLD
(a) Switching Methods with Fixed threshold
bull The switching from one branch to the other occurs when the signal level falls below a threshold value
bull The threshold value is fixedbull However this threshold value is not
necessarily the best over the entire service area
FIXED THERSHOLD
(b) Switching Methods with Variable threshold
bull Here the threshold value is adjusted dynamically as the vehicle moves
bull It includes the feedback using Estimationbull But it may introduce the envelope and phase
transients that will reduce the performance improvement
VARIABLE THERSHOLD
Conclusions
bull The diversity is used to provide the receiver with several replicas of the same signal
bull Diversity techniques are used to improve the performance of the radio channel without any increase in the transmitted power
bull As higher as the received signal replicas are decorrelated as much as the diversity gain
Thank you for you attention
- No trade off to
- What are all the needs of diversity techniques
- CONCEPTS OF DIVERSITY BRANCH AND SIGNAL PATH
- (a) Branch Construction method using frequency diversity
- (b) Branch Construction method using Time diversity
- COMBINING AND SWITCHNING METHODS
- Slide 29
- FOR COHERENT DETECTION
- (a) Maximal ratio combining (MRC)
- Slide 32
- (b) Equal Gain Combining (EGC)
- EGC
- For VHF UHF and microwave wireless radio applications
- (c) Selection or Switching Combining
- Slide 37
- Disadvantage of Selection or Switching
- Slide 39
- (a) Switching Methods with Fixed threshold
- Slide 41
- (b) Switching Methods with Variable threshold
- Slide 43
-
Switch-and-stay combining (SSC) Switch-and-examine combining (SEC)
h1
h2
x
ComparatorChannelestimator
switchingthreshold
bullSwitched diversity
No trade off to
Without excessively increasing
bull 1 transmitting powerbull 2 Co-channel reuse distance
bull One of the most effective technique to solve this issue is diversity reception technique
What are all the needs of diversity techniques
bull 1No of signal transmission pathsbull 2A circuit to combine the received signal or
select one of them
CONCEPTS OF DIVERSITY BRANCH AND SIGNAL PATH
(a) Branch Construction method using frequency diversity
(b) Branch Construction method using Time diversity
COMBINING AND SWITCHNING METHODS
COMBINING AND SWITCHNINGMETHODS
FOR COHERENT DETECTION
FOR NON - COHERENT DETECTION
FOR COHERENT DETECTION
bull There is no difference whether the combining is carried out in the pre detection or in the post detection stage
FOR NON-COHERENT DETECTION
bull There is a difference in performance exists between whether pre detection amp post detection combining methods
(a) Maximal ratio combining (MRC)
bull MRC is the best performance improvement compared with the other methods
bull However the trade off is It requires 1 cophasing 2 weighting 3summing circuitsResulting in most complicated implementationComplexity performance
(b) Equal Gain Combining (EGC)
EGCbull EGC is similar to MRC except the weighting
circuits are omittedbull The performance improvement obtained by
equal gain combiner is slightly inferior to that of a MRC since the interference and noise corrupted signal combined with high quality signals
For VHF UHF and microwave wireless radio applications
bull Both MRC and EGC methods are unsuitablebull Compared with MRC EGC methods the
selection method is more suitable for mobile radio applications because of its simple implementation
(c) Selection or Switching Combining
bull The diversity branch having the highest signal level (or) lowest Pe is selected
bull Also in addition stable operation is easily achieved even in the fast multipath fading environments
bull But the performance improvement obtained by the selection method is still only slightly inferior to that of MRC method
Disadvantage of Selection or Switching
bull Combining The continuous monitoring of the signals requires the same no of receivers as the no of diversity branches
bull This redundancy can be alleviated by the use of switching or scanning receiver
SWITCHNINGMETHODS
FIXED THERSHOLD VARIABLE THERSHOLD
(a) Switching Methods with Fixed threshold
bull The switching from one branch to the other occurs when the signal level falls below a threshold value
bull The threshold value is fixedbull However this threshold value is not
necessarily the best over the entire service area
FIXED THERSHOLD
(b) Switching Methods with Variable threshold
bull Here the threshold value is adjusted dynamically as the vehicle moves
bull It includes the feedback using Estimationbull But it may introduce the envelope and phase
transients that will reduce the performance improvement
VARIABLE THERSHOLD
Conclusions
bull The diversity is used to provide the receiver with several replicas of the same signal
bull Diversity techniques are used to improve the performance of the radio channel without any increase in the transmitted power
bull As higher as the received signal replicas are decorrelated as much as the diversity gain
Thank you for you attention
- No trade off to
- What are all the needs of diversity techniques
- CONCEPTS OF DIVERSITY BRANCH AND SIGNAL PATH
- (a) Branch Construction method using frequency diversity
- (b) Branch Construction method using Time diversity
- COMBINING AND SWITCHNING METHODS
- Slide 29
- FOR COHERENT DETECTION
- (a) Maximal ratio combining (MRC)
- Slide 32
- (b) Equal Gain Combining (EGC)
- EGC
- For VHF UHF and microwave wireless radio applications
- (c) Selection or Switching Combining
- Slide 37
- Disadvantage of Selection or Switching
- Slide 39
- (a) Switching Methods with Fixed threshold
- Slide 41
- (b) Switching Methods with Variable threshold
- Slide 43
-
No trade off to
Without excessively increasing
bull 1 transmitting powerbull 2 Co-channel reuse distance
bull One of the most effective technique to solve this issue is diversity reception technique
What are all the needs of diversity techniques
bull 1No of signal transmission pathsbull 2A circuit to combine the received signal or
select one of them
CONCEPTS OF DIVERSITY BRANCH AND SIGNAL PATH
(a) Branch Construction method using frequency diversity
(b) Branch Construction method using Time diversity
COMBINING AND SWITCHNING METHODS
COMBINING AND SWITCHNINGMETHODS
FOR COHERENT DETECTION
FOR NON - COHERENT DETECTION
FOR COHERENT DETECTION
bull There is no difference whether the combining is carried out in the pre detection or in the post detection stage
FOR NON-COHERENT DETECTION
bull There is a difference in performance exists between whether pre detection amp post detection combining methods
(a) Maximal ratio combining (MRC)
bull MRC is the best performance improvement compared with the other methods
bull However the trade off is It requires 1 cophasing 2 weighting 3summing circuitsResulting in most complicated implementationComplexity performance
(b) Equal Gain Combining (EGC)
EGCbull EGC is similar to MRC except the weighting
circuits are omittedbull The performance improvement obtained by
equal gain combiner is slightly inferior to that of a MRC since the interference and noise corrupted signal combined with high quality signals
For VHF UHF and microwave wireless radio applications
bull Both MRC and EGC methods are unsuitablebull Compared with MRC EGC methods the
selection method is more suitable for mobile radio applications because of its simple implementation
(c) Selection or Switching Combining
bull The diversity branch having the highest signal level (or) lowest Pe is selected
bull Also in addition stable operation is easily achieved even in the fast multipath fading environments
bull But the performance improvement obtained by the selection method is still only slightly inferior to that of MRC method
Disadvantage of Selection or Switching
bull Combining The continuous monitoring of the signals requires the same no of receivers as the no of diversity branches
bull This redundancy can be alleviated by the use of switching or scanning receiver
SWITCHNINGMETHODS
FIXED THERSHOLD VARIABLE THERSHOLD
(a) Switching Methods with Fixed threshold
bull The switching from one branch to the other occurs when the signal level falls below a threshold value
bull The threshold value is fixedbull However this threshold value is not
necessarily the best over the entire service area
FIXED THERSHOLD
(b) Switching Methods with Variable threshold
bull Here the threshold value is adjusted dynamically as the vehicle moves
bull It includes the feedback using Estimationbull But it may introduce the envelope and phase
transients that will reduce the performance improvement
VARIABLE THERSHOLD
Conclusions
bull The diversity is used to provide the receiver with several replicas of the same signal
bull Diversity techniques are used to improve the performance of the radio channel without any increase in the transmitted power
bull As higher as the received signal replicas are decorrelated as much as the diversity gain
Thank you for you attention
- No trade off to
- What are all the needs of diversity techniques
- CONCEPTS OF DIVERSITY BRANCH AND SIGNAL PATH
- (a) Branch Construction method using frequency diversity
- (b) Branch Construction method using Time diversity
- COMBINING AND SWITCHNING METHODS
- Slide 29
- FOR COHERENT DETECTION
- (a) Maximal ratio combining (MRC)
- Slide 32
- (b) Equal Gain Combining (EGC)
- EGC
- For VHF UHF and microwave wireless radio applications
- (c) Selection or Switching Combining
- Slide 37
- Disadvantage of Selection or Switching
- Slide 39
- (a) Switching Methods with Fixed threshold
- Slide 41
- (b) Switching Methods with Variable threshold
- Slide 43
-
What are all the needs of diversity techniques
bull 1No of signal transmission pathsbull 2A circuit to combine the received signal or
select one of them
CONCEPTS OF DIVERSITY BRANCH AND SIGNAL PATH
(a) Branch Construction method using frequency diversity
(b) Branch Construction method using Time diversity
COMBINING AND SWITCHNING METHODS
COMBINING AND SWITCHNINGMETHODS
FOR COHERENT DETECTION
FOR NON - COHERENT DETECTION
FOR COHERENT DETECTION
bull There is no difference whether the combining is carried out in the pre detection or in the post detection stage
FOR NON-COHERENT DETECTION
bull There is a difference in performance exists between whether pre detection amp post detection combining methods
(a) Maximal ratio combining (MRC)
bull MRC is the best performance improvement compared with the other methods
bull However the trade off is It requires 1 cophasing 2 weighting 3summing circuitsResulting in most complicated implementationComplexity performance
(b) Equal Gain Combining (EGC)
EGCbull EGC is similar to MRC except the weighting
circuits are omittedbull The performance improvement obtained by
equal gain combiner is slightly inferior to that of a MRC since the interference and noise corrupted signal combined with high quality signals
For VHF UHF and microwave wireless radio applications
bull Both MRC and EGC methods are unsuitablebull Compared with MRC EGC methods the
selection method is more suitable for mobile radio applications because of its simple implementation
(c) Selection or Switching Combining
bull The diversity branch having the highest signal level (or) lowest Pe is selected
bull Also in addition stable operation is easily achieved even in the fast multipath fading environments
bull But the performance improvement obtained by the selection method is still only slightly inferior to that of MRC method
Disadvantage of Selection or Switching
bull Combining The continuous monitoring of the signals requires the same no of receivers as the no of diversity branches
bull This redundancy can be alleviated by the use of switching or scanning receiver
SWITCHNINGMETHODS
FIXED THERSHOLD VARIABLE THERSHOLD
(a) Switching Methods with Fixed threshold
bull The switching from one branch to the other occurs when the signal level falls below a threshold value
bull The threshold value is fixedbull However this threshold value is not
necessarily the best over the entire service area
FIXED THERSHOLD
(b) Switching Methods with Variable threshold
bull Here the threshold value is adjusted dynamically as the vehicle moves
bull It includes the feedback using Estimationbull But it may introduce the envelope and phase
transients that will reduce the performance improvement
VARIABLE THERSHOLD
Conclusions
bull The diversity is used to provide the receiver with several replicas of the same signal
bull Diversity techniques are used to improve the performance of the radio channel without any increase in the transmitted power
bull As higher as the received signal replicas are decorrelated as much as the diversity gain
Thank you for you attention
- No trade off to
- What are all the needs of diversity techniques
- CONCEPTS OF DIVERSITY BRANCH AND SIGNAL PATH
- (a) Branch Construction method using frequency diversity
- (b) Branch Construction method using Time diversity
- COMBINING AND SWITCHNING METHODS
- Slide 29
- FOR COHERENT DETECTION
- (a) Maximal ratio combining (MRC)
- Slide 32
- (b) Equal Gain Combining (EGC)
- EGC
- For VHF UHF and microwave wireless radio applications
- (c) Selection or Switching Combining
- Slide 37
- Disadvantage of Selection or Switching
- Slide 39
- (a) Switching Methods with Fixed threshold
- Slide 41
- (b) Switching Methods with Variable threshold
- Slide 43
-
CONCEPTS OF DIVERSITY BRANCH AND SIGNAL PATH
(a) Branch Construction method using frequency diversity
(b) Branch Construction method using Time diversity
COMBINING AND SWITCHNING METHODS
COMBINING AND SWITCHNINGMETHODS
FOR COHERENT DETECTION
FOR NON - COHERENT DETECTION
FOR COHERENT DETECTION
bull There is no difference whether the combining is carried out in the pre detection or in the post detection stage
FOR NON-COHERENT DETECTION
bull There is a difference in performance exists between whether pre detection amp post detection combining methods
(a) Maximal ratio combining (MRC)
bull MRC is the best performance improvement compared with the other methods
bull However the trade off is It requires 1 cophasing 2 weighting 3summing circuitsResulting in most complicated implementationComplexity performance
(b) Equal Gain Combining (EGC)
EGCbull EGC is similar to MRC except the weighting
circuits are omittedbull The performance improvement obtained by
equal gain combiner is slightly inferior to that of a MRC since the interference and noise corrupted signal combined with high quality signals
For VHF UHF and microwave wireless radio applications
bull Both MRC and EGC methods are unsuitablebull Compared with MRC EGC methods the
selection method is more suitable for mobile radio applications because of its simple implementation
(c) Selection or Switching Combining
bull The diversity branch having the highest signal level (or) lowest Pe is selected
bull Also in addition stable operation is easily achieved even in the fast multipath fading environments
bull But the performance improvement obtained by the selection method is still only slightly inferior to that of MRC method
Disadvantage of Selection or Switching
bull Combining The continuous monitoring of the signals requires the same no of receivers as the no of diversity branches
bull This redundancy can be alleviated by the use of switching or scanning receiver
SWITCHNINGMETHODS
FIXED THERSHOLD VARIABLE THERSHOLD
(a) Switching Methods with Fixed threshold
bull The switching from one branch to the other occurs when the signal level falls below a threshold value
bull The threshold value is fixedbull However this threshold value is not
necessarily the best over the entire service area
FIXED THERSHOLD
(b) Switching Methods with Variable threshold
bull Here the threshold value is adjusted dynamically as the vehicle moves
bull It includes the feedback using Estimationbull But it may introduce the envelope and phase
transients that will reduce the performance improvement
VARIABLE THERSHOLD
Conclusions
bull The diversity is used to provide the receiver with several replicas of the same signal
bull Diversity techniques are used to improve the performance of the radio channel without any increase in the transmitted power
bull As higher as the received signal replicas are decorrelated as much as the diversity gain
Thank you for you attention
- No trade off to
- What are all the needs of diversity techniques
- CONCEPTS OF DIVERSITY BRANCH AND SIGNAL PATH
- (a) Branch Construction method using frequency diversity
- (b) Branch Construction method using Time diversity
- COMBINING AND SWITCHNING METHODS
- Slide 29
- FOR COHERENT DETECTION
- (a) Maximal ratio combining (MRC)
- Slide 32
- (b) Equal Gain Combining (EGC)
- EGC
- For VHF UHF and microwave wireless radio applications
- (c) Selection or Switching Combining
- Slide 37
- Disadvantage of Selection or Switching
- Slide 39
- (a) Switching Methods with Fixed threshold
- Slide 41
- (b) Switching Methods with Variable threshold
- Slide 43
-
(a) Branch Construction method using frequency diversity
(b) Branch Construction method using Time diversity
COMBINING AND SWITCHNING METHODS
COMBINING AND SWITCHNINGMETHODS
FOR COHERENT DETECTION
FOR NON - COHERENT DETECTION
FOR COHERENT DETECTION
bull There is no difference whether the combining is carried out in the pre detection or in the post detection stage
FOR NON-COHERENT DETECTION
bull There is a difference in performance exists between whether pre detection amp post detection combining methods
(a) Maximal ratio combining (MRC)
bull MRC is the best performance improvement compared with the other methods
bull However the trade off is It requires 1 cophasing 2 weighting 3summing circuitsResulting in most complicated implementationComplexity performance
(b) Equal Gain Combining (EGC)
EGCbull EGC is similar to MRC except the weighting
circuits are omittedbull The performance improvement obtained by
equal gain combiner is slightly inferior to that of a MRC since the interference and noise corrupted signal combined with high quality signals
For VHF UHF and microwave wireless radio applications
bull Both MRC and EGC methods are unsuitablebull Compared with MRC EGC methods the
selection method is more suitable for mobile radio applications because of its simple implementation
(c) Selection or Switching Combining
bull The diversity branch having the highest signal level (or) lowest Pe is selected
bull Also in addition stable operation is easily achieved even in the fast multipath fading environments
bull But the performance improvement obtained by the selection method is still only slightly inferior to that of MRC method
Disadvantage of Selection or Switching
bull Combining The continuous monitoring of the signals requires the same no of receivers as the no of diversity branches
bull This redundancy can be alleviated by the use of switching or scanning receiver
SWITCHNINGMETHODS
FIXED THERSHOLD VARIABLE THERSHOLD
(a) Switching Methods with Fixed threshold
bull The switching from one branch to the other occurs when the signal level falls below a threshold value
bull The threshold value is fixedbull However this threshold value is not
necessarily the best over the entire service area
FIXED THERSHOLD
(b) Switching Methods with Variable threshold
bull Here the threshold value is adjusted dynamically as the vehicle moves
bull It includes the feedback using Estimationbull But it may introduce the envelope and phase
transients that will reduce the performance improvement
VARIABLE THERSHOLD
Conclusions
bull The diversity is used to provide the receiver with several replicas of the same signal
bull Diversity techniques are used to improve the performance of the radio channel without any increase in the transmitted power
bull As higher as the received signal replicas are decorrelated as much as the diversity gain
Thank you for you attention
- No trade off to
- What are all the needs of diversity techniques
- CONCEPTS OF DIVERSITY BRANCH AND SIGNAL PATH
- (a) Branch Construction method using frequency diversity
- (b) Branch Construction method using Time diversity
- COMBINING AND SWITCHNING METHODS
- Slide 29
- FOR COHERENT DETECTION
- (a) Maximal ratio combining (MRC)
- Slide 32
- (b) Equal Gain Combining (EGC)
- EGC
- For VHF UHF and microwave wireless radio applications
- (c) Selection or Switching Combining
- Slide 37
- Disadvantage of Selection or Switching
- Slide 39
- (a) Switching Methods with Fixed threshold
- Slide 41
- (b) Switching Methods with Variable threshold
- Slide 43
-
(b) Branch Construction method using Time diversity
COMBINING AND SWITCHNING METHODS
COMBINING AND SWITCHNINGMETHODS
FOR COHERENT DETECTION
FOR NON - COHERENT DETECTION
FOR COHERENT DETECTION
bull There is no difference whether the combining is carried out in the pre detection or in the post detection stage
FOR NON-COHERENT DETECTION
bull There is a difference in performance exists between whether pre detection amp post detection combining methods
(a) Maximal ratio combining (MRC)
bull MRC is the best performance improvement compared with the other methods
bull However the trade off is It requires 1 cophasing 2 weighting 3summing circuitsResulting in most complicated implementationComplexity performance
(b) Equal Gain Combining (EGC)
EGCbull EGC is similar to MRC except the weighting
circuits are omittedbull The performance improvement obtained by
equal gain combiner is slightly inferior to that of a MRC since the interference and noise corrupted signal combined with high quality signals
For VHF UHF and microwave wireless radio applications
bull Both MRC and EGC methods are unsuitablebull Compared with MRC EGC methods the
selection method is more suitable for mobile radio applications because of its simple implementation
(c) Selection or Switching Combining
bull The diversity branch having the highest signal level (or) lowest Pe is selected
bull Also in addition stable operation is easily achieved even in the fast multipath fading environments
bull But the performance improvement obtained by the selection method is still only slightly inferior to that of MRC method
Disadvantage of Selection or Switching
bull Combining The continuous monitoring of the signals requires the same no of receivers as the no of diversity branches
bull This redundancy can be alleviated by the use of switching or scanning receiver
SWITCHNINGMETHODS
FIXED THERSHOLD VARIABLE THERSHOLD
(a) Switching Methods with Fixed threshold
bull The switching from one branch to the other occurs when the signal level falls below a threshold value
bull The threshold value is fixedbull However this threshold value is not
necessarily the best over the entire service area
FIXED THERSHOLD
(b) Switching Methods with Variable threshold
bull Here the threshold value is adjusted dynamically as the vehicle moves
bull It includes the feedback using Estimationbull But it may introduce the envelope and phase
transients that will reduce the performance improvement
VARIABLE THERSHOLD
Conclusions
bull The diversity is used to provide the receiver with several replicas of the same signal
bull Diversity techniques are used to improve the performance of the radio channel without any increase in the transmitted power
bull As higher as the received signal replicas are decorrelated as much as the diversity gain
Thank you for you attention
- No trade off to
- What are all the needs of diversity techniques
- CONCEPTS OF DIVERSITY BRANCH AND SIGNAL PATH
- (a) Branch Construction method using frequency diversity
- (b) Branch Construction method using Time diversity
- COMBINING AND SWITCHNING METHODS
- Slide 29
- FOR COHERENT DETECTION
- (a) Maximal ratio combining (MRC)
- Slide 32
- (b) Equal Gain Combining (EGC)
- EGC
- For VHF UHF and microwave wireless radio applications
- (c) Selection or Switching Combining
- Slide 37
- Disadvantage of Selection or Switching
- Slide 39
- (a) Switching Methods with Fixed threshold
- Slide 41
- (b) Switching Methods with Variable threshold
- Slide 43
-
COMBINING AND SWITCHNING METHODS
COMBINING AND SWITCHNINGMETHODS
FOR COHERENT DETECTION
FOR NON - COHERENT DETECTION
FOR COHERENT DETECTION
bull There is no difference whether the combining is carried out in the pre detection or in the post detection stage
FOR NON-COHERENT DETECTION
bull There is a difference in performance exists between whether pre detection amp post detection combining methods
(a) Maximal ratio combining (MRC)
bull MRC is the best performance improvement compared with the other methods
bull However the trade off is It requires 1 cophasing 2 weighting 3summing circuitsResulting in most complicated implementationComplexity performance
(b) Equal Gain Combining (EGC)
EGCbull EGC is similar to MRC except the weighting
circuits are omittedbull The performance improvement obtained by
equal gain combiner is slightly inferior to that of a MRC since the interference and noise corrupted signal combined with high quality signals
For VHF UHF and microwave wireless radio applications
bull Both MRC and EGC methods are unsuitablebull Compared with MRC EGC methods the
selection method is more suitable for mobile radio applications because of its simple implementation
(c) Selection or Switching Combining
bull The diversity branch having the highest signal level (or) lowest Pe is selected
bull Also in addition stable operation is easily achieved even in the fast multipath fading environments
bull But the performance improvement obtained by the selection method is still only slightly inferior to that of MRC method
Disadvantage of Selection or Switching
bull Combining The continuous monitoring of the signals requires the same no of receivers as the no of diversity branches
bull This redundancy can be alleviated by the use of switching or scanning receiver
SWITCHNINGMETHODS
FIXED THERSHOLD VARIABLE THERSHOLD
(a) Switching Methods with Fixed threshold
bull The switching from one branch to the other occurs when the signal level falls below a threshold value
bull The threshold value is fixedbull However this threshold value is not
necessarily the best over the entire service area
FIXED THERSHOLD
(b) Switching Methods with Variable threshold
bull Here the threshold value is adjusted dynamically as the vehicle moves
bull It includes the feedback using Estimationbull But it may introduce the envelope and phase
transients that will reduce the performance improvement
VARIABLE THERSHOLD
Conclusions
bull The diversity is used to provide the receiver with several replicas of the same signal
bull Diversity techniques are used to improve the performance of the radio channel without any increase in the transmitted power
bull As higher as the received signal replicas are decorrelated as much as the diversity gain
Thank you for you attention
- No trade off to
- What are all the needs of diversity techniques
- CONCEPTS OF DIVERSITY BRANCH AND SIGNAL PATH
- (a) Branch Construction method using frequency diversity
- (b) Branch Construction method using Time diversity
- COMBINING AND SWITCHNING METHODS
- Slide 29
- FOR COHERENT DETECTION
- (a) Maximal ratio combining (MRC)
- Slide 32
- (b) Equal Gain Combining (EGC)
- EGC
- For VHF UHF and microwave wireless radio applications
- (c) Selection or Switching Combining
- Slide 37
- Disadvantage of Selection or Switching
- Slide 39
- (a) Switching Methods with Fixed threshold
- Slide 41
- (b) Switching Methods with Variable threshold
- Slide 43
-
COMBINING AND SWITCHNINGMETHODS
FOR COHERENT DETECTION
FOR NON - COHERENT DETECTION
FOR COHERENT DETECTION
bull There is no difference whether the combining is carried out in the pre detection or in the post detection stage
FOR NON-COHERENT DETECTION
bull There is a difference in performance exists between whether pre detection amp post detection combining methods
(a) Maximal ratio combining (MRC)
bull MRC is the best performance improvement compared with the other methods
bull However the trade off is It requires 1 cophasing 2 weighting 3summing circuitsResulting in most complicated implementationComplexity performance
(b) Equal Gain Combining (EGC)
EGCbull EGC is similar to MRC except the weighting
circuits are omittedbull The performance improvement obtained by
equal gain combiner is slightly inferior to that of a MRC since the interference and noise corrupted signal combined with high quality signals
For VHF UHF and microwave wireless radio applications
bull Both MRC and EGC methods are unsuitablebull Compared with MRC EGC methods the
selection method is more suitable for mobile radio applications because of its simple implementation
(c) Selection or Switching Combining
bull The diversity branch having the highest signal level (or) lowest Pe is selected
bull Also in addition stable operation is easily achieved even in the fast multipath fading environments
bull But the performance improvement obtained by the selection method is still only slightly inferior to that of MRC method
Disadvantage of Selection or Switching
bull Combining The continuous monitoring of the signals requires the same no of receivers as the no of diversity branches
bull This redundancy can be alleviated by the use of switching or scanning receiver
SWITCHNINGMETHODS
FIXED THERSHOLD VARIABLE THERSHOLD
(a) Switching Methods with Fixed threshold
bull The switching from one branch to the other occurs when the signal level falls below a threshold value
bull The threshold value is fixedbull However this threshold value is not
necessarily the best over the entire service area
FIXED THERSHOLD
(b) Switching Methods with Variable threshold
bull Here the threshold value is adjusted dynamically as the vehicle moves
bull It includes the feedback using Estimationbull But it may introduce the envelope and phase
transients that will reduce the performance improvement
VARIABLE THERSHOLD
Conclusions
bull The diversity is used to provide the receiver with several replicas of the same signal
bull Diversity techniques are used to improve the performance of the radio channel without any increase in the transmitted power
bull As higher as the received signal replicas are decorrelated as much as the diversity gain
Thank you for you attention
- No trade off to
- What are all the needs of diversity techniques
- CONCEPTS OF DIVERSITY BRANCH AND SIGNAL PATH
- (a) Branch Construction method using frequency diversity
- (b) Branch Construction method using Time diversity
- COMBINING AND SWITCHNING METHODS
- Slide 29
- FOR COHERENT DETECTION
- (a) Maximal ratio combining (MRC)
- Slide 32
- (b) Equal Gain Combining (EGC)
- EGC
- For VHF UHF and microwave wireless radio applications
- (c) Selection or Switching Combining
- Slide 37
- Disadvantage of Selection or Switching
- Slide 39
- (a) Switching Methods with Fixed threshold
- Slide 41
- (b) Switching Methods with Variable threshold
- Slide 43
-
FOR COHERENT DETECTION
bull There is no difference whether the combining is carried out in the pre detection or in the post detection stage
FOR NON-COHERENT DETECTION
bull There is a difference in performance exists between whether pre detection amp post detection combining methods
(a) Maximal ratio combining (MRC)
bull MRC is the best performance improvement compared with the other methods
bull However the trade off is It requires 1 cophasing 2 weighting 3summing circuitsResulting in most complicated implementationComplexity performance
(b) Equal Gain Combining (EGC)
EGCbull EGC is similar to MRC except the weighting
circuits are omittedbull The performance improvement obtained by
equal gain combiner is slightly inferior to that of a MRC since the interference and noise corrupted signal combined with high quality signals
For VHF UHF and microwave wireless radio applications
bull Both MRC and EGC methods are unsuitablebull Compared with MRC EGC methods the
selection method is more suitable for mobile radio applications because of its simple implementation
(c) Selection or Switching Combining
bull The diversity branch having the highest signal level (or) lowest Pe is selected
bull Also in addition stable operation is easily achieved even in the fast multipath fading environments
bull But the performance improvement obtained by the selection method is still only slightly inferior to that of MRC method
Disadvantage of Selection or Switching
bull Combining The continuous monitoring of the signals requires the same no of receivers as the no of diversity branches
bull This redundancy can be alleviated by the use of switching or scanning receiver
SWITCHNINGMETHODS
FIXED THERSHOLD VARIABLE THERSHOLD
(a) Switching Methods with Fixed threshold
bull The switching from one branch to the other occurs when the signal level falls below a threshold value
bull The threshold value is fixedbull However this threshold value is not
necessarily the best over the entire service area
FIXED THERSHOLD
(b) Switching Methods with Variable threshold
bull Here the threshold value is adjusted dynamically as the vehicle moves
bull It includes the feedback using Estimationbull But it may introduce the envelope and phase
transients that will reduce the performance improvement
VARIABLE THERSHOLD
Conclusions
bull The diversity is used to provide the receiver with several replicas of the same signal
bull Diversity techniques are used to improve the performance of the radio channel without any increase in the transmitted power
bull As higher as the received signal replicas are decorrelated as much as the diversity gain
Thank you for you attention
- No trade off to
- What are all the needs of diversity techniques
- CONCEPTS OF DIVERSITY BRANCH AND SIGNAL PATH
- (a) Branch Construction method using frequency diversity
- (b) Branch Construction method using Time diversity
- COMBINING AND SWITCHNING METHODS
- Slide 29
- FOR COHERENT DETECTION
- (a) Maximal ratio combining (MRC)
- Slide 32
- (b) Equal Gain Combining (EGC)
- EGC
- For VHF UHF and microwave wireless radio applications
- (c) Selection or Switching Combining
- Slide 37
- Disadvantage of Selection or Switching
- Slide 39
- (a) Switching Methods with Fixed threshold
- Slide 41
- (b) Switching Methods with Variable threshold
- Slide 43
-
(a) Maximal ratio combining (MRC)
bull MRC is the best performance improvement compared with the other methods
bull However the trade off is It requires 1 cophasing 2 weighting 3summing circuitsResulting in most complicated implementationComplexity performance
(b) Equal Gain Combining (EGC)
EGCbull EGC is similar to MRC except the weighting
circuits are omittedbull The performance improvement obtained by
equal gain combiner is slightly inferior to that of a MRC since the interference and noise corrupted signal combined with high quality signals
For VHF UHF and microwave wireless radio applications
bull Both MRC and EGC methods are unsuitablebull Compared with MRC EGC methods the
selection method is more suitable for mobile radio applications because of its simple implementation
(c) Selection or Switching Combining
bull The diversity branch having the highest signal level (or) lowest Pe is selected
bull Also in addition stable operation is easily achieved even in the fast multipath fading environments
bull But the performance improvement obtained by the selection method is still only slightly inferior to that of MRC method
Disadvantage of Selection or Switching
bull Combining The continuous monitoring of the signals requires the same no of receivers as the no of diversity branches
bull This redundancy can be alleviated by the use of switching or scanning receiver
SWITCHNINGMETHODS
FIXED THERSHOLD VARIABLE THERSHOLD
(a) Switching Methods with Fixed threshold
bull The switching from one branch to the other occurs when the signal level falls below a threshold value
bull The threshold value is fixedbull However this threshold value is not
necessarily the best over the entire service area
FIXED THERSHOLD
(b) Switching Methods with Variable threshold
bull Here the threshold value is adjusted dynamically as the vehicle moves
bull It includes the feedback using Estimationbull But it may introduce the envelope and phase
transients that will reduce the performance improvement
VARIABLE THERSHOLD
Conclusions
bull The diversity is used to provide the receiver with several replicas of the same signal
bull Diversity techniques are used to improve the performance of the radio channel without any increase in the transmitted power
bull As higher as the received signal replicas are decorrelated as much as the diversity gain
Thank you for you attention
- No trade off to
- What are all the needs of diversity techniques
- CONCEPTS OF DIVERSITY BRANCH AND SIGNAL PATH
- (a) Branch Construction method using frequency diversity
- (b) Branch Construction method using Time diversity
- COMBINING AND SWITCHNING METHODS
- Slide 29
- FOR COHERENT DETECTION
- (a) Maximal ratio combining (MRC)
- Slide 32
- (b) Equal Gain Combining (EGC)
- EGC
- For VHF UHF and microwave wireless radio applications
- (c) Selection or Switching Combining
- Slide 37
- Disadvantage of Selection or Switching
- Slide 39
- (a) Switching Methods with Fixed threshold
- Slide 41
- (b) Switching Methods with Variable threshold
- Slide 43
-
bull MRC is the best performance improvement compared with the other methods
bull However the trade off is It requires 1 cophasing 2 weighting 3summing circuitsResulting in most complicated implementationComplexity performance
(b) Equal Gain Combining (EGC)
EGCbull EGC is similar to MRC except the weighting
circuits are omittedbull The performance improvement obtained by
equal gain combiner is slightly inferior to that of a MRC since the interference and noise corrupted signal combined with high quality signals
For VHF UHF and microwave wireless radio applications
bull Both MRC and EGC methods are unsuitablebull Compared with MRC EGC methods the
selection method is more suitable for mobile radio applications because of its simple implementation
(c) Selection or Switching Combining
bull The diversity branch having the highest signal level (or) lowest Pe is selected
bull Also in addition stable operation is easily achieved even in the fast multipath fading environments
bull But the performance improvement obtained by the selection method is still only slightly inferior to that of MRC method
Disadvantage of Selection or Switching
bull Combining The continuous monitoring of the signals requires the same no of receivers as the no of diversity branches
bull This redundancy can be alleviated by the use of switching or scanning receiver
SWITCHNINGMETHODS
FIXED THERSHOLD VARIABLE THERSHOLD
(a) Switching Methods with Fixed threshold
bull The switching from one branch to the other occurs when the signal level falls below a threshold value
bull The threshold value is fixedbull However this threshold value is not
necessarily the best over the entire service area
FIXED THERSHOLD
(b) Switching Methods with Variable threshold
bull Here the threshold value is adjusted dynamically as the vehicle moves
bull It includes the feedback using Estimationbull But it may introduce the envelope and phase
transients that will reduce the performance improvement
VARIABLE THERSHOLD
Conclusions
bull The diversity is used to provide the receiver with several replicas of the same signal
bull Diversity techniques are used to improve the performance of the radio channel without any increase in the transmitted power
bull As higher as the received signal replicas are decorrelated as much as the diversity gain
Thank you for you attention
- No trade off to
- What are all the needs of diversity techniques
- CONCEPTS OF DIVERSITY BRANCH AND SIGNAL PATH
- (a) Branch Construction method using frequency diversity
- (b) Branch Construction method using Time diversity
- COMBINING AND SWITCHNING METHODS
- Slide 29
- FOR COHERENT DETECTION
- (a) Maximal ratio combining (MRC)
- Slide 32
- (b) Equal Gain Combining (EGC)
- EGC
- For VHF UHF and microwave wireless radio applications
- (c) Selection or Switching Combining
- Slide 37
- Disadvantage of Selection or Switching
- Slide 39
- (a) Switching Methods with Fixed threshold
- Slide 41
- (b) Switching Methods with Variable threshold
- Slide 43
-
(b) Equal Gain Combining (EGC)
EGCbull EGC is similar to MRC except the weighting
circuits are omittedbull The performance improvement obtained by
equal gain combiner is slightly inferior to that of a MRC since the interference and noise corrupted signal combined with high quality signals
For VHF UHF and microwave wireless radio applications
bull Both MRC and EGC methods are unsuitablebull Compared with MRC EGC methods the
selection method is more suitable for mobile radio applications because of its simple implementation
(c) Selection or Switching Combining
bull The diversity branch having the highest signal level (or) lowest Pe is selected
bull Also in addition stable operation is easily achieved even in the fast multipath fading environments
bull But the performance improvement obtained by the selection method is still only slightly inferior to that of MRC method
Disadvantage of Selection or Switching
bull Combining The continuous monitoring of the signals requires the same no of receivers as the no of diversity branches
bull This redundancy can be alleviated by the use of switching or scanning receiver
SWITCHNINGMETHODS
FIXED THERSHOLD VARIABLE THERSHOLD
(a) Switching Methods with Fixed threshold
bull The switching from one branch to the other occurs when the signal level falls below a threshold value
bull The threshold value is fixedbull However this threshold value is not
necessarily the best over the entire service area
FIXED THERSHOLD
(b) Switching Methods with Variable threshold
bull Here the threshold value is adjusted dynamically as the vehicle moves
bull It includes the feedback using Estimationbull But it may introduce the envelope and phase
transients that will reduce the performance improvement
VARIABLE THERSHOLD
Conclusions
bull The diversity is used to provide the receiver with several replicas of the same signal
bull Diversity techniques are used to improve the performance of the radio channel without any increase in the transmitted power
bull As higher as the received signal replicas are decorrelated as much as the diversity gain
Thank you for you attention
- No trade off to
- What are all the needs of diversity techniques
- CONCEPTS OF DIVERSITY BRANCH AND SIGNAL PATH
- (a) Branch Construction method using frequency diversity
- (b) Branch Construction method using Time diversity
- COMBINING AND SWITCHNING METHODS
- Slide 29
- FOR COHERENT DETECTION
- (a) Maximal ratio combining (MRC)
- Slide 32
- (b) Equal Gain Combining (EGC)
- EGC
- For VHF UHF and microwave wireless radio applications
- (c) Selection or Switching Combining
- Slide 37
- Disadvantage of Selection or Switching
- Slide 39
- (a) Switching Methods with Fixed threshold
- Slide 41
- (b) Switching Methods with Variable threshold
- Slide 43
-
EGCbull EGC is similar to MRC except the weighting
circuits are omittedbull The performance improvement obtained by
equal gain combiner is slightly inferior to that of a MRC since the interference and noise corrupted signal combined with high quality signals
For VHF UHF and microwave wireless radio applications
bull Both MRC and EGC methods are unsuitablebull Compared with MRC EGC methods the
selection method is more suitable for mobile radio applications because of its simple implementation
(c) Selection or Switching Combining
bull The diversity branch having the highest signal level (or) lowest Pe is selected
bull Also in addition stable operation is easily achieved even in the fast multipath fading environments
bull But the performance improvement obtained by the selection method is still only slightly inferior to that of MRC method
Disadvantage of Selection or Switching
bull Combining The continuous monitoring of the signals requires the same no of receivers as the no of diversity branches
bull This redundancy can be alleviated by the use of switching or scanning receiver
SWITCHNINGMETHODS
FIXED THERSHOLD VARIABLE THERSHOLD
(a) Switching Methods with Fixed threshold
bull The switching from one branch to the other occurs when the signal level falls below a threshold value
bull The threshold value is fixedbull However this threshold value is not
necessarily the best over the entire service area
FIXED THERSHOLD
(b) Switching Methods with Variable threshold
bull Here the threshold value is adjusted dynamically as the vehicle moves
bull It includes the feedback using Estimationbull But it may introduce the envelope and phase
transients that will reduce the performance improvement
VARIABLE THERSHOLD
Conclusions
bull The diversity is used to provide the receiver with several replicas of the same signal
bull Diversity techniques are used to improve the performance of the radio channel without any increase in the transmitted power
bull As higher as the received signal replicas are decorrelated as much as the diversity gain
Thank you for you attention
- No trade off to
- What are all the needs of diversity techniques
- CONCEPTS OF DIVERSITY BRANCH AND SIGNAL PATH
- (a) Branch Construction method using frequency diversity
- (b) Branch Construction method using Time diversity
- COMBINING AND SWITCHNING METHODS
- Slide 29
- FOR COHERENT DETECTION
- (a) Maximal ratio combining (MRC)
- Slide 32
- (b) Equal Gain Combining (EGC)
- EGC
- For VHF UHF and microwave wireless radio applications
- (c) Selection or Switching Combining
- Slide 37
- Disadvantage of Selection or Switching
- Slide 39
- (a) Switching Methods with Fixed threshold
- Slide 41
- (b) Switching Methods with Variable threshold
- Slide 43
-
For VHF UHF and microwave wireless radio applications
bull Both MRC and EGC methods are unsuitablebull Compared with MRC EGC methods the
selection method is more suitable for mobile radio applications because of its simple implementation
(c) Selection or Switching Combining
bull The diversity branch having the highest signal level (or) lowest Pe is selected
bull Also in addition stable operation is easily achieved even in the fast multipath fading environments
bull But the performance improvement obtained by the selection method is still only slightly inferior to that of MRC method
Disadvantage of Selection or Switching
bull Combining The continuous monitoring of the signals requires the same no of receivers as the no of diversity branches
bull This redundancy can be alleviated by the use of switching or scanning receiver
SWITCHNINGMETHODS
FIXED THERSHOLD VARIABLE THERSHOLD
(a) Switching Methods with Fixed threshold
bull The switching from one branch to the other occurs when the signal level falls below a threshold value
bull The threshold value is fixedbull However this threshold value is not
necessarily the best over the entire service area
FIXED THERSHOLD
(b) Switching Methods with Variable threshold
bull Here the threshold value is adjusted dynamically as the vehicle moves
bull It includes the feedback using Estimationbull But it may introduce the envelope and phase
transients that will reduce the performance improvement
VARIABLE THERSHOLD
Conclusions
bull The diversity is used to provide the receiver with several replicas of the same signal
bull Diversity techniques are used to improve the performance of the radio channel without any increase in the transmitted power
bull As higher as the received signal replicas are decorrelated as much as the diversity gain
Thank you for you attention
- No trade off to
- What are all the needs of diversity techniques
- CONCEPTS OF DIVERSITY BRANCH AND SIGNAL PATH
- (a) Branch Construction method using frequency diversity
- (b) Branch Construction method using Time diversity
- COMBINING AND SWITCHNING METHODS
- Slide 29
- FOR COHERENT DETECTION
- (a) Maximal ratio combining (MRC)
- Slide 32
- (b) Equal Gain Combining (EGC)
- EGC
- For VHF UHF and microwave wireless radio applications
- (c) Selection or Switching Combining
- Slide 37
- Disadvantage of Selection or Switching
- Slide 39
- (a) Switching Methods with Fixed threshold
- Slide 41
- (b) Switching Methods with Variable threshold
- Slide 43
-
(c) Selection or Switching Combining
bull The diversity branch having the highest signal level (or) lowest Pe is selected
bull Also in addition stable operation is easily achieved even in the fast multipath fading environments
bull But the performance improvement obtained by the selection method is still only slightly inferior to that of MRC method
Disadvantage of Selection or Switching
bull Combining The continuous monitoring of the signals requires the same no of receivers as the no of diversity branches
bull This redundancy can be alleviated by the use of switching or scanning receiver
SWITCHNINGMETHODS
FIXED THERSHOLD VARIABLE THERSHOLD
(a) Switching Methods with Fixed threshold
bull The switching from one branch to the other occurs when the signal level falls below a threshold value
bull The threshold value is fixedbull However this threshold value is not
necessarily the best over the entire service area
FIXED THERSHOLD
(b) Switching Methods with Variable threshold
bull Here the threshold value is adjusted dynamically as the vehicle moves
bull It includes the feedback using Estimationbull But it may introduce the envelope and phase
transients that will reduce the performance improvement
VARIABLE THERSHOLD
Conclusions
bull The diversity is used to provide the receiver with several replicas of the same signal
bull Diversity techniques are used to improve the performance of the radio channel without any increase in the transmitted power
bull As higher as the received signal replicas are decorrelated as much as the diversity gain
Thank you for you attention
- No trade off to
- What are all the needs of diversity techniques
- CONCEPTS OF DIVERSITY BRANCH AND SIGNAL PATH
- (a) Branch Construction method using frequency diversity
- (b) Branch Construction method using Time diversity
- COMBINING AND SWITCHNING METHODS
- Slide 29
- FOR COHERENT DETECTION
- (a) Maximal ratio combining (MRC)
- Slide 32
- (b) Equal Gain Combining (EGC)
- EGC
- For VHF UHF and microwave wireless radio applications
- (c) Selection or Switching Combining
- Slide 37
- Disadvantage of Selection or Switching
- Slide 39
- (a) Switching Methods with Fixed threshold
- Slide 41
- (b) Switching Methods with Variable threshold
- Slide 43
-
bull The diversity branch having the highest signal level (or) lowest Pe is selected
bull Also in addition stable operation is easily achieved even in the fast multipath fading environments
bull But the performance improvement obtained by the selection method is still only slightly inferior to that of MRC method
Disadvantage of Selection or Switching
bull Combining The continuous monitoring of the signals requires the same no of receivers as the no of diversity branches
bull This redundancy can be alleviated by the use of switching or scanning receiver
SWITCHNINGMETHODS
FIXED THERSHOLD VARIABLE THERSHOLD
(a) Switching Methods with Fixed threshold
bull The switching from one branch to the other occurs when the signal level falls below a threshold value
bull The threshold value is fixedbull However this threshold value is not
necessarily the best over the entire service area
FIXED THERSHOLD
(b) Switching Methods with Variable threshold
bull Here the threshold value is adjusted dynamically as the vehicle moves
bull It includes the feedback using Estimationbull But it may introduce the envelope and phase
transients that will reduce the performance improvement
VARIABLE THERSHOLD
Conclusions
bull The diversity is used to provide the receiver with several replicas of the same signal
bull Diversity techniques are used to improve the performance of the radio channel without any increase in the transmitted power
bull As higher as the received signal replicas are decorrelated as much as the diversity gain
Thank you for you attention
- No trade off to
- What are all the needs of diversity techniques
- CONCEPTS OF DIVERSITY BRANCH AND SIGNAL PATH
- (a) Branch Construction method using frequency diversity
- (b) Branch Construction method using Time diversity
- COMBINING AND SWITCHNING METHODS
- Slide 29
- FOR COHERENT DETECTION
- (a) Maximal ratio combining (MRC)
- Slide 32
- (b) Equal Gain Combining (EGC)
- EGC
- For VHF UHF and microwave wireless radio applications
- (c) Selection or Switching Combining
- Slide 37
- Disadvantage of Selection or Switching
- Slide 39
- (a) Switching Methods with Fixed threshold
- Slide 41
- (b) Switching Methods with Variable threshold
- Slide 43
-
Disadvantage of Selection or Switching
bull Combining The continuous monitoring of the signals requires the same no of receivers as the no of diversity branches
bull This redundancy can be alleviated by the use of switching or scanning receiver
SWITCHNINGMETHODS
FIXED THERSHOLD VARIABLE THERSHOLD
(a) Switching Methods with Fixed threshold
bull The switching from one branch to the other occurs when the signal level falls below a threshold value
bull The threshold value is fixedbull However this threshold value is not
necessarily the best over the entire service area
FIXED THERSHOLD
(b) Switching Methods with Variable threshold
bull Here the threshold value is adjusted dynamically as the vehicle moves
bull It includes the feedback using Estimationbull But it may introduce the envelope and phase
transients that will reduce the performance improvement
VARIABLE THERSHOLD
Conclusions
bull The diversity is used to provide the receiver with several replicas of the same signal
bull Diversity techniques are used to improve the performance of the radio channel without any increase in the transmitted power
bull As higher as the received signal replicas are decorrelated as much as the diversity gain
Thank you for you attention
- No trade off to
- What are all the needs of diversity techniques
- CONCEPTS OF DIVERSITY BRANCH AND SIGNAL PATH
- (a) Branch Construction method using frequency diversity
- (b) Branch Construction method using Time diversity
- COMBINING AND SWITCHNING METHODS
- Slide 29
- FOR COHERENT DETECTION
- (a) Maximal ratio combining (MRC)
- Slide 32
- (b) Equal Gain Combining (EGC)
- EGC
- For VHF UHF and microwave wireless radio applications
- (c) Selection or Switching Combining
- Slide 37
- Disadvantage of Selection or Switching
- Slide 39
- (a) Switching Methods with Fixed threshold
- Slide 41
- (b) Switching Methods with Variable threshold
- Slide 43
-
SWITCHNINGMETHODS
FIXED THERSHOLD VARIABLE THERSHOLD
(a) Switching Methods with Fixed threshold
bull The switching from one branch to the other occurs when the signal level falls below a threshold value
bull The threshold value is fixedbull However this threshold value is not
necessarily the best over the entire service area
FIXED THERSHOLD
(b) Switching Methods with Variable threshold
bull Here the threshold value is adjusted dynamically as the vehicle moves
bull It includes the feedback using Estimationbull But it may introduce the envelope and phase
transients that will reduce the performance improvement
VARIABLE THERSHOLD
Conclusions
bull The diversity is used to provide the receiver with several replicas of the same signal
bull Diversity techniques are used to improve the performance of the radio channel without any increase in the transmitted power
bull As higher as the received signal replicas are decorrelated as much as the diversity gain
Thank you for you attention
- No trade off to
- What are all the needs of diversity techniques
- CONCEPTS OF DIVERSITY BRANCH AND SIGNAL PATH
- (a) Branch Construction method using frequency diversity
- (b) Branch Construction method using Time diversity
- COMBINING AND SWITCHNING METHODS
- Slide 29
- FOR COHERENT DETECTION
- (a) Maximal ratio combining (MRC)
- Slide 32
- (b) Equal Gain Combining (EGC)
- EGC
- For VHF UHF and microwave wireless radio applications
- (c) Selection or Switching Combining
- Slide 37
- Disadvantage of Selection or Switching
- Slide 39
- (a) Switching Methods with Fixed threshold
- Slide 41
- (b) Switching Methods with Variable threshold
- Slide 43
-
(a) Switching Methods with Fixed threshold
bull The switching from one branch to the other occurs when the signal level falls below a threshold value
bull The threshold value is fixedbull However this threshold value is not
necessarily the best over the entire service area
FIXED THERSHOLD
(b) Switching Methods with Variable threshold
bull Here the threshold value is adjusted dynamically as the vehicle moves
bull It includes the feedback using Estimationbull But it may introduce the envelope and phase
transients that will reduce the performance improvement
VARIABLE THERSHOLD
Conclusions
bull The diversity is used to provide the receiver with several replicas of the same signal
bull Diversity techniques are used to improve the performance of the radio channel without any increase in the transmitted power
bull As higher as the received signal replicas are decorrelated as much as the diversity gain
Thank you for you attention
- No trade off to
- What are all the needs of diversity techniques
- CONCEPTS OF DIVERSITY BRANCH AND SIGNAL PATH
- (a) Branch Construction method using frequency diversity
- (b) Branch Construction method using Time diversity
- COMBINING AND SWITCHNING METHODS
- Slide 29
- FOR COHERENT DETECTION
- (a) Maximal ratio combining (MRC)
- Slide 32
- (b) Equal Gain Combining (EGC)
- EGC
- For VHF UHF and microwave wireless radio applications
- (c) Selection or Switching Combining
- Slide 37
- Disadvantage of Selection or Switching
- Slide 39
- (a) Switching Methods with Fixed threshold
- Slide 41
- (b) Switching Methods with Variable threshold
- Slide 43
-
bull The switching from one branch to the other occurs when the signal level falls below a threshold value
bull The threshold value is fixedbull However this threshold value is not
necessarily the best over the entire service area
FIXED THERSHOLD
(b) Switching Methods with Variable threshold
bull Here the threshold value is adjusted dynamically as the vehicle moves
bull It includes the feedback using Estimationbull But it may introduce the envelope and phase
transients that will reduce the performance improvement
VARIABLE THERSHOLD
Conclusions
bull The diversity is used to provide the receiver with several replicas of the same signal
bull Diversity techniques are used to improve the performance of the radio channel without any increase in the transmitted power
bull As higher as the received signal replicas are decorrelated as much as the diversity gain
Thank you for you attention
- No trade off to
- What are all the needs of diversity techniques
- CONCEPTS OF DIVERSITY BRANCH AND SIGNAL PATH
- (a) Branch Construction method using frequency diversity
- (b) Branch Construction method using Time diversity
- COMBINING AND SWITCHNING METHODS
- Slide 29
- FOR COHERENT DETECTION
- (a) Maximal ratio combining (MRC)
- Slide 32
- (b) Equal Gain Combining (EGC)
- EGC
- For VHF UHF and microwave wireless radio applications
- (c) Selection or Switching Combining
- Slide 37
- Disadvantage of Selection or Switching
- Slide 39
- (a) Switching Methods with Fixed threshold
- Slide 41
- (b) Switching Methods with Variable threshold
- Slide 43
-
(b) Switching Methods with Variable threshold
bull Here the threshold value is adjusted dynamically as the vehicle moves
bull It includes the feedback using Estimationbull But it may introduce the envelope and phase
transients that will reduce the performance improvement
VARIABLE THERSHOLD
Conclusions
bull The diversity is used to provide the receiver with several replicas of the same signal
bull Diversity techniques are used to improve the performance of the radio channel without any increase in the transmitted power
bull As higher as the received signal replicas are decorrelated as much as the diversity gain
Thank you for you attention
- No trade off to
- What are all the needs of diversity techniques
- CONCEPTS OF DIVERSITY BRANCH AND SIGNAL PATH
- (a) Branch Construction method using frequency diversity
- (b) Branch Construction method using Time diversity
- COMBINING AND SWITCHNING METHODS
- Slide 29
- FOR COHERENT DETECTION
- (a) Maximal ratio combining (MRC)
- Slide 32
- (b) Equal Gain Combining (EGC)
- EGC
- For VHF UHF and microwave wireless radio applications
- (c) Selection or Switching Combining
- Slide 37
- Disadvantage of Selection or Switching
- Slide 39
- (a) Switching Methods with Fixed threshold
- Slide 41
- (b) Switching Methods with Variable threshold
- Slide 43
-
bull Here the threshold value is adjusted dynamically as the vehicle moves
bull It includes the feedback using Estimationbull But it may introduce the envelope and phase
transients that will reduce the performance improvement
VARIABLE THERSHOLD
Conclusions
bull The diversity is used to provide the receiver with several replicas of the same signal
bull Diversity techniques are used to improve the performance of the radio channel without any increase in the transmitted power
bull As higher as the received signal replicas are decorrelated as much as the diversity gain
Thank you for you attention
- No trade off to
- What are all the needs of diversity techniques
- CONCEPTS OF DIVERSITY BRANCH AND SIGNAL PATH
- (a) Branch Construction method using frequency diversity
- (b) Branch Construction method using Time diversity
- COMBINING AND SWITCHNING METHODS
- Slide 29
- FOR COHERENT DETECTION
- (a) Maximal ratio combining (MRC)
- Slide 32
- (b) Equal Gain Combining (EGC)
- EGC
- For VHF UHF and microwave wireless radio applications
- (c) Selection or Switching Combining
- Slide 37
- Disadvantage of Selection or Switching
- Slide 39
- (a) Switching Methods with Fixed threshold
- Slide 41
- (b) Switching Methods with Variable threshold
- Slide 43
-
Conclusions
bull The diversity is used to provide the receiver with several replicas of the same signal
bull Diversity techniques are used to improve the performance of the radio channel without any increase in the transmitted power
bull As higher as the received signal replicas are decorrelated as much as the diversity gain
Thank you for you attention
- No trade off to
- What are all the needs of diversity techniques
- CONCEPTS OF DIVERSITY BRANCH AND SIGNAL PATH
- (a) Branch Construction method using frequency diversity
- (b) Branch Construction method using Time diversity
- COMBINING AND SWITCHNING METHODS
- Slide 29
- FOR COHERENT DETECTION
- (a) Maximal ratio combining (MRC)
- Slide 32
- (b) Equal Gain Combining (EGC)
- EGC
- For VHF UHF and microwave wireless radio applications
- (c) Selection or Switching Combining
- Slide 37
- Disadvantage of Selection or Switching
- Slide 39
- (a) Switching Methods with Fixed threshold
- Slide 41
- (b) Switching Methods with Variable threshold
- Slide 43
-
Thank you for you attention
- No trade off to
- What are all the needs of diversity techniques
- CONCEPTS OF DIVERSITY BRANCH AND SIGNAL PATH
- (a) Branch Construction method using frequency diversity
- (b) Branch Construction method using Time diversity
- COMBINING AND SWITCHNING METHODS
- Slide 29
- FOR COHERENT DETECTION
- (a) Maximal ratio combining (MRC)
- Slide 32
- (b) Equal Gain Combining (EGC)
- EGC
- For VHF UHF and microwave wireless radio applications
- (c) Selection or Switching Combining
- Slide 37
- Disadvantage of Selection or Switching
- Slide 39
- (a) Switching Methods with Fixed threshold
- Slide 41
- (b) Switching Methods with Variable threshold
- Slide 43
-