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Transcript of Training Material_WCDMA Wireless Principle and Key Technology.ppt
8/10/2019 Training Material_WCDMA Wireless Principle and Key Technology.ppt
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WCDMA Wireless Princip le and
Key Technology
-UMTS Radio Network Planning & Optimization Dept
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秘密▲
WCDMA System Overview
WCDMA Wireless Principle
WCDMA Key Technology
Contents
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秘密▲ Evolution of Cellular Mobile
Communication SystemFirst
Generat ion(80s’)
Analog
Third
Generation
(2000)
Wideband
Multimedia
Second
Generat ion(90s’)
Digital
AMPS
TACS
NMT
Others
A n a l o g
T e c h n o l o g y
GSM
CDMAIS95
TDMA
IS-136
PDC
Market
Driven
UMTS
WCDMA
CDMA
2000
Market
Driven
TD-
SCDMA
D i g i t a l T e c h n o l o g y
V o i c e S e r v i c e
B r o a d b a n d S e r v i c e
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秘密▲
Background of 3G
Essential impetus: a wider range
and higher data rate of services,
higher spectrum efficiency
Improve the compatibility betweendifferent networks
The international standard—IMT-
2000 comes forth as the
requirement
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秘密▲
Target of IMT-2000
Uniform frequency, uniform standard, seamless
coverage
High efficient utilization of spectrum
High quality, high security
Easy evolution to 2G
Provide various new services
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秘密▲
Wireless Interface Technologies of IMT-2000
16 candidate tech., including 10 land mobile tech., 6 satellite tech.
Land mobile tech includes 8 FDD, 5 TDD
Dominating ground tech:
W-CDMA (Including 5 similar Tech. such as USA W-CDMA and
WIMS, which are merged as WP-CDMA)
CDMA2000 (Including 2 similar Tech.)
UWC-136
TD-SCDMA submitted by China
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秘密▲
Wireless Interface Standards of IMT-2000
IMT-FT
IMT-2000
FDMA/TDM
A
IMT-SC
IMT-2000
TDMA SC
UWC-136 E-DECT
IS-136 DECT
IMT-DS
CDMA DS
IMT-MC
CDMA MC
IMT-TD
CDMA TDD
WCDMA TD-SCDMA
UMTS TDD
CDMA 2000
UMTS FDD
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秘密▲
3G Technology Evolution
3G
Standard
WCDMA
TD-SCDMA CDMA2000
CDMA is the Mainstream Technology of 3G
CN:based on MAP
CN:based on ANSI-41 CN:based on MAP
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秘密▲
3G Standard and Beyond 3G Evolution
TD-SCDMAEnhancedTD-SCDMA
2005
• R4 • R5/6LTE
FDD/TDD• HSDPA
Phase1
• HSUPA
Phase1
• HSDPA
Phase2
•HSUPA
Phase2
• MBMS•WCDMA
•R4
2004 2005 2006 2007 2008 After 2009
• R5 • R6
•CDMA
•1X
• EV-DO 0 • EV-DO A
• BCMCSAIE
Phase 2
AIE
Phase1
N×DO
3GPP 4G
3GPP2 4G
WiMAX
802.16d
WiMAX
802.16e
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秘密▲
WCDMA Standard Evolution
Introduce Iu Interface
MAX. Speed: 2Mbps
Commercial Release
2001.6+ following CR
R99
R4
R5
R6
2000.3 2001.3 2002.6 Time for function frozen
Control and Bearer
Separation
Introduce IMS Domain
Introduce HSDPA for
Radio Interface
Study on Interoperability of
IMS and PLMN/PSTN/ISDN
Circuit Switch Network MBMS
Study on Frame Structure
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秘密▲
Characteristics of WCDMA
Bidirectional fast closed-loop power control
Bidirectional coherent demodulation by pilots
Transmitter and receiver diversity
High chip rate(3.84Mcps)
Channel coding tech with high gain
Unnecessary for GPS synchronization among basestations
Multiple switching technology
Multiple transport rate
Advanced radio resource management algorithm
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秘密▲
WCDMA Entire IP Network EvolutionR99
Billing
Server
OMC
SCP
HLR
MMSC
GMLC
MSCGMSC GGSNSGSN
PSCS
R99 CN smoothly evolves from
GSM/GPRS network
R4 CN separate the Control Plane
from Bearer Plane in CS Domain
R5 CN Introduces IMS,
RAN Adopts IP
RNSBSS
MGWGMGW GGSNSGSN
PSCS
R4 R5
BillingServerOMC
SCP
HLR
MMSC
GMLC
CS
MSCserver
GMSCserver
BillingServer
OMC
SCP
HLR
MMSC
GMLC
BSS RNSRNS
BSS
MGWGMGW GGSNSGSN
PSCS
WCDMA Entire IP Network Evolution coincide with the
development tendency of the next generation network
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秘密▲
WCDMA CDMA2000
Carrier spacing 5M 1.25/5/10/15/20 MHz
Chip rate 3.84M N*1.2288Mcps N=1,3,6,9,12
Spreading way DS-CDMA DS-CDMA & MC-CDMA
Duplex mode FDD/TDD FDD
Frame size 10ms 20ms(general data and control channel) 5ms(basic and designated control channel)
Channel coding Convolutional codes, Turbo codes Convolutional codes, Turbo codes
Interleave Intra-cutting, inter-cutting Intra-cutting
Scrambling Walsh+Gold sequence Walsh+M sequence
Modulation mode QPSK/BPSK QPSK/BPSK
Power control Open-loop and fast closed-loop
1.5KHz)
Open-loop and fast closed-loop(800Hz)
Base station
synchronization
Synchronization/Asynchronous synchronization
Comparison of the Three 3G Technologies (I)
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秘密▲
WCDMA-TDD TD-SCDMA
Carrier spacing 5M 1.6M
Chip rate 3.84M 1.28M
Spreading way DS-CDMA, SF=1,2,4,8,16 DS-CDMA, SF=1,2,4,8,16
Duplex mode TDD TDD
Modulation mode QPSK/BPSK QPSK
Number of timeslot 15 7
Capacity
(channel number each timeslot)
8 16
Channel number each carrier 56 48
Capacity
(rate of one timeslot)
220.8kbps 281.6kbps
Rate of one carrier 3.31Mbps 1.971Mbps
Spectrum Utilization 0.662Mbps/MHz 1.232Mbps
Comparison of the Three 3G Technologies (II)
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秘密▲
WCDMA System Overview
WCDMA Wireless Principle
WCDMA Key Technology
Contents
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秘密▲
Radio Propagation Characteristics
Multi Access
Spreading Technology
Channel Coding
Interleave Technology
Diversity Technology
The Basic Principles ofWireless Communication
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秘密▲
Characteristic of Radio Propagation
Electromagnetic propagation: direct radiation、
reflection、diffraction and scattering
Signal attenuation:
Path loss: Loss of electromagnetic waves in large scope of
the spread reflects the trend of the received signal in the
spreading。 Slow fading:Loss because of being blocked by the building
and hill in the propagation path
Fast fading:Electromagnetic signals rapidly decline in a fewdozens wavelength ranges
Description of Fast fading distribution Rayleigh distribution:non line-of –sight transmission
Rician distribution:line-of –sight transmission
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秘密▲
Frequency off -set caused by the mo vement of mo bi le that
is Dopp ler effect
Sending signal Accepting signal
Interference
0dB
Sending signal
-25dB
Accepting signal
fading
0 +
Sending signal Accepting signal
delay
0 2 3 +
Sending signal Accepting signal
dithering
Characteristics of Radio Propagation
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秘密▲
Multi-Path Effects
receiving signal
time
strength
0
sending signal
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秘密▲
Radio Propagation Characteristics
Multi Access
Spreading Technology
Channel Coding
Interleave Technology
Diversity Technology
The Basic Principles of
Wireless Communication
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秘密▲
Power
Power
Power
FDMA
TDMA
CDMA
Frequency division multiple
access technology Channels in different frequency are
allocated to different users, e.g. TACS
AMPS
Time division multiple accesstechnology channels in different time are allocated to
different users, e.g. GSM
DAMPS
Code division multiple accesstechnology
Users distinguished by scramble code, e.g.
CDMA
Multiple Access
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秘密▲
Radio Propagation Characteristics
Multi Access
Spreading Technology
Channel Coding
Interleave Technology
Diversity Technology
The Basic Principles of
Wireless Communication
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秘密▲ Principle of Spreading Frequency
A technology of transmission technology after spreading
frequency of signal.
Theoretical Basis: Shannon theory C=Wlog2(1+S/N)
Fast
Spreading
Sequence
Slow
Information
Sent
TX
Slow
Information
Recovered
RX
Fast
Spreading
Sequence
Wideband
Signal
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秘密▲ Spreading Mode
Direct sequence spread(DS-SS)
Base band data is spreaded by multiplication of pseudo-noise sequence and base-
band pulse, the pseudo-noise sequence generated by the pseudo-noise generator
BER subject to Multiple Access Interference and near-far effect
Power control can overcome the near-far effect, but it is limited by power detection
accuracy
WCDMA uses DS-SS
Frequency hopping spread(FH-SS)
Data is transmitted in the random channel by the carrier frequency hopping
Before FH again, data is transmitted using traditional narrowband modulation
No near-far effect
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秘密▲ Characteristics of Spreading Communication
High anti-multi-path- interference capability
Anti-sudden-pulse
High security
Lower transmitting power
Easy to implement large-capacity Multiple Access
Communication
Occupy band wide
Complex realization
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秘密▲
Radio Propagation Characteristics
Multi Access
Spreading Technology
Channel Coding
Interleave Technology
Diversity Technology
The Basic Principles of
Wireless Communication
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秘密▲
Purpose of Channel Coding
purpose: By adding redundant information in the original data
stream, receivers can detect and correct the error
signal, and improve data transmission rates.
No correct coding: BER<10-1 ~ 10-2Can not satisfy
the communication
Convolutional coding:BER<10-3Can satisfy the
speech communication
Turbo coding: BER<10-6 Can satisfy the
data communication
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P i i l f I l T h l
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秘密▲ Principle of Interleave Technology
Advantage
Interleave is to change the sequence of data to random theunexpected errors
Advance the correcting validity
Disadvantage:
Increase the processing delay
Especially, Several independent random errors may
intertwined for the unexpected error .
x1 x6 x11 x16 x21
x2 x7 … x22
x3 x8 … x23
x4 x9 … x24
x5 x10 … x25
Data input A = (x1 x2 x3 x4 x5 … x25)
Data output A’= (x1 x6 x11 x16… x25)
e.g.
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秘密▲
Radio Propagation Characteristics
Multi Access
Spreading Technology
Channel Coding
Interleave Technology
Diversity Technology
The Basic Principles of
Wireless Communication
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秘密▲
Concept of Diversity Technology
Double meanings:scattered transmission, concentrative
process.
Achieved by using and finding the independent multi-access
signals in the wireless communication environment .
If the signals in one path decay seriously, but in other
independent path are still strong.
Advantage:
Easy to achieve relatively stable signal
Achieve the diversity gain
Improve SNR
秘密
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秘密▲
Diversity Categories
Space diversity
Also called antenna diversity, if the distance between the antennaeis greater than half of the wavelength, the signals from different
antenna are not related.
Time diversity
The signal repeats over Channel Coherent time interval, so that theenvironment is independent.
Frequency diversity
The signal repeats in the different frequencies.
Polarization Diversity
Signal reflects in the different direction, since the reflection
coefficients of different polarization directions are not the same, the
signals in different polarization direction is not related
秘密▲
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秘密▲
WCDMA System Overview
WCDMA Wireless Principle A
The Basic Principles of Wireless
Communication
WCDMA Wireless Technology
WCDMA Key Technology
Contents
秘密▲
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秘密▲
Spreading Technology of WCDMA
Channel Coding of WCDMA
Interleave Technology of WCDMA
Diversity Technology of WCDMA
WCDMA Wireless Technology
秘密▲
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秘密▲
Symbol rate×
SF = 3.84Mcps
WCDMA,
SF of uplink channeliezd code:
4~256
SF of downlink channelized code:4~512
OVSF: Orthogonal Variable Spreading Factor
OVSF Code Scramble Code
Data bit
Chip
after
Spreading
Spreading of WCDMA
秘密▲
S di S bli d d l ti f WCDMA
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秘密▲
∑
∑
Real part
and
Imaginary part
separate
Pulse
shaping
Pulse
shaping
serial
parallel
transfer
serialparallel
transfer
……
……
DL physical channel 1Cch,SF,m
j
I+jQ
Sdl,n
G1
Cch,SF,m
j
I+jQ
Sdl,n
G2
DL physical channel 2Gp
Gp
P-SCH
S-SCH
cos(wt)
-sin(wt)
T
T
Re(T)
Im(T)
Spreading, Scrambling and modulation of WCDMA
Downlink physical channel spreading and modulation:
秘密▲
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秘密▲
Real part
and
Imaginary part
separate
Pulse
shaping
Pulse
shaping
cos(wt)
-sin(wt)
Sdpch,n
S
Re(S)
Im(S)
∑
Cd,1 βd
I
cc
Q
j
I+jQ
∑
∑
DPDCH1
Cd,3 βdDPDCH3
Cd,5 βdDPDCH5
Cd,2 βdDPDCH2
Cd,4 βdDPDCH4
Cd,6 βdDPDCH6
ccCc βcDPCCH
Q
Spreading, Scrambling and modulation of WCDMA
Uplink physical channel spreading and modulation:
秘密▲
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秘密▲
Despreading of WCDMA
Method of despreading
Input signal
Local PN code
When T=Ts, judge
Output after despreading
integral
0
Ts
(*)dt
秘密▲
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秘密▲
Symbol
Spreading
Despreading
1
-1
1
-1
1
-1
1
-1
1
-1
Data =
010010
Spreading code
Spread signal= Data × code
Spreading code =
1 -1 -1 1 -1 1 1 -1
( SF = 8 )
Data =Spread signal× code
Chip
ketch map of Spreading and Despreading of WCDMA
秘密▲
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秘密▲
Spreading Gain
Spreading definition and processing gain
Processing gain: PG=Wc/R
Wc: chip rate
R: signal rate
PG=10lg(Wc/R), dB units
Despreading by receiver will be able to resume the
original signal
More spreading of multiples, higher the processing
gain, stronger anti-jamming
秘密▲
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秘密▲
Spreading Technology of WCDMA
Channel Coding of WCDMA
Interleave Technology of WCDMA
Diversity Technology of WCDMA
WCDMA Wireless Technology
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秘密▲Characteristics of Convolutional code
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秘密▲ Characteristics of Convolutional code
Easy decode
Short delay
Generally use the Viterbi Algorithm
Channel bit error rate is 10-3 magnitude
Suitable to realtime service e.g. speech and video service.
秘密▲
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秘密▲
Turbo Code Used in Data service channel
Code Rate is 1/3
Can be implemented in the transmission for large block and long delayservices
Turbo coding structure is based on two or more weak error control code
combinations. The information bits are interleaved in the two Encoder,
and generate two information flow. At last, this information can be
multiplexed and punctured Decoding needs cycle iterative calculation
Interleaver
Encoder 1
Encoder 2
M u l t i p l e xinput output
秘密▲
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秘密▲
Characteristics of Turbo Codes
Complex decoding
Use the LOG-MAP arithmetic
Channel bit error rate is 10-6 magnitude
Very suitable to non-realtime package
service which is BER sensitive & delay
insensitive , e.g. WWW, FTP, E_mail ,
multimedia transmission.
秘密▲
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秘密▲
Spreading Technology of WCDMA
Channel Coding of WCDMA
Interleave Technology of WCDMA
Diversity Technology of WCDMA
WCDMA Wireless Technology
秘密▲
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秘密▲
Interleave Technology of WCDMA
Intra-frame interleave
Bits transform in the internal frame
Inter-frame interleave
Data transform among the frames
Intra-Turbo codes interleave
Complex nesting of intra-frame and inter-frame interleave
秘密▲
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秘密
Spreading Technology of WCDMA
Channel Coding of WCDMA
Interleave Technology of WCDMA
Diversity Technology of WCDMA
WCDMA Wireless Technology
秘密▲
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秘密
Diversity Technology of WCDMA
Open-loop transmit diversity
Use space-time coding , fire from two antenna,
comprehensively utilize the time and space diversity
Closed-loop transmit diversity
Feedback from the receiver controls the parameters of the
transmitting antenna, it is the time diversity with feedbacktechnology.
Interleave
A implied time diversity
RAKE receive technology
A implied time diversity. The multi-access signal used byRAKE is considered the signal sent by transmitter several
times.
秘密▲
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秘密
WCDMA System Overview
WCDMA Wireless Principle A
WCDMA Key Technology
WCDMA Capacity Feature
Radio Resource Management
WCDMA Key Technology
Contents
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Capacity of WCDMA
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Power Rise
Power rising occurs because of the Multiple Access Interference
(MAI) resulting from the non-orthogonal code channels.
WCDMA network Meeting Room
Code channel transmit talk with dialects
Channel power voice tone
Promised channel quality listen clearly
Channel power rise voice tone rise
Power climb voice climb
Collapse over the range can not listen for each other
Interference outside the cell Noise outside the room
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秘密▲
WCDMA C it F t
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WCDMA Capacity Feature
WCDMA capacity feature
WCDMA capacity is Soft Capacity
Concept of soft capacity
Inter-convertibility between system capacity and
communication quality
Different service has different capacity
Different proportion of services has different capacity
for mixed services
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S ft C it
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Trade off between System capacity and service quality
Different service
combination and
proportion has
different capacity
Soft Capacity
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C i l F f WCDMA C i
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Capacity
All the WCDMA technologies adopted is try to achieve
the most optimal balance of the three factors
Crucial Factors for WCDMA Capacity
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F t Aff ti WCDMA C it
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Factors Impact on WCDMA capacity Category
Power Control Reducing interference, saving power and Increasing capacity
Radio Resource
Management
RRM
Handover ControlImpacting the capacity through applying different proportion and
algorithm of soft handover
Admission Control Admitting a connection base on the load and the admission threshold of
planned capacity
Load Control Monitoring system load and adjusting the ongoing services to avoid
overload
OVSF Code The Allocation of codes impacts the maximum number of simultaneous
connections.
RAKE Receiver The advanced receiving and baseband processing technology is
introduced to overcome the fast fading
Key TechnologySmart Antenna Reducing interference, saving power and expanding coverage through
tracking the user with beam forming antenna array.
MUDReducing the Multi-Access Interference (MAI).
Service Class and
CombinationThe class and combination of services impact the capacity directly Service Attribute
Wireless
EnvironmentWireless environment such as interferences, UE position and mobility
etc. can influent the cell capacity
Wireless
Propagation
Environment
Factors Affecting WCDMA Capacity
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Power Control
Handover Control
Compressed Mode
Admission Control
Load Control
Code Allocation Spreading
Radio Resource Management
秘密▲
Power Control
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Power Control
CDMA is not a new technology
Power control is a key technology of CDMA system
Power control is the key path for launching the large scale
CDMA commercial network
CDMA is a typical self-interference system, thus the chief
principle is that any potential surplus transmitted power forservice must be controlled.
秘密▲
Near Far Effect
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Each term inal is an
inter ference sou rce to the
oth ers. The Near-far effect
wi l l impact the capacity
t remendous ly
Power
f
Power contro l wi l l reduce
the cros s inter ference
s igni f icant ly and improve
the total capacity
Near-Far Effect
Power
f
秘密▲ Multi-Access Interference
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Multi Access Interference
WCDMA is a self-interference system Cause: Spectrum sharing; lacking of idealized self-
correlated and cross-correlated spread codes.
Phenomenon: Power Rising
Frequency
Time
Codes
Mu l t i - A c c e s s In t e r f e r en c e S k e t c h Map
Output
Time Synchronizat ion
秘密▲
Purpose of Power Control
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Purpose of Power Control
• Overcome near-far effect and compensate signal fading
• Reduce multi-access interference and guarantee cell capacity
• Extend battery life
Downlink Power Control
Cell transmitted power
Report power control bit (TPC)
UE transmitted signal
Power control command (TPC)
Uplink Power Control
秘密▲
Category of Power Control
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Category of Power Control
Open Loop
Measure the channel interference condition and adjust the initialtransmitted power
Close Loop-
Inner Loop
Measure the SIR (Signaling to Interference Ratio), compare with the
target SIR value, and then send power control instruction to UE.The frequency of CDMA close loop power control is 1500Hz.
If measured SIR>target SIR, decrease the UE transmitted
power.
If measured SIR <target SIR, increase the UE transmitted
power.
Close Loop-
Outer Loop
Measure the BLER (Block Error Rate), and adjust the target SIR.
秘密▲
Open Loop Power Control
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Open Loop Power Control
General principals of open loop power control
Open loop power control is applied to estimate the initial
transmitted code power (TCP) for a new radio link.
The downlink Open Loop Power Control is using P-CPICH
signal which is measured by UE to estimate the initial TCP
and the following factors will also be considered, such as
service QoS and data rate, Eb/No requirements of
establishing service, current downlink total Transmitted
Power and interference from neighbor cell etc..
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秘密▲ Close Loop – Inner Loop Power Control
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Close Loop Inner Loop Power Control
General principals of inner loop power control
The receiver compares the SIR value of received signal with target SIR, and
then sends back TPC instruction. According to the instruction, the sender
will decide to increase/decrease the transmitted power, The adjusted
rang=TPC_cmd×TPC_STEP_SIZE
Inner loop power control is required for the following
channels:
DPCH, PDSCH, PCPCH
Inner loop power control is not required for the following
channels:
P-CPICH(S-CPICH), P-CCPCH(S-CCPCH), PRACH etc..
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Close Loop Outer Loop Power Control
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NodeB UE
TPC instruction
Inner loop
Set SIRtar
Get data flow
with stable BLER
Measure BLER
of TRCH
Outer Loop
RNC
Measure receiving
BLER and compare to
target BLER
Set BLERtar
10-100Hz
Close Loop – Outer Loop Power Control
Measure receiving SIR
and
compare to target SIR
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Close Loop Open Loop Power Control
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Close Loop – Open Loop Power Control
General principals of open loop power control
The algorithm is implemented as following: Employ the inner loop
power control to keep SIR close to target SIR; Measure the quality of
service, e.g. through CRCI report, and tune the target SIR with pre-
defined step; Therefore keep the call in good quality event in changing
wireless propagation environment.
Input parameters include target BLER, CRC indicator and SIR Error,
output parameter is SIR Target.
Open loop power control algorithm is implemented in two ways: FER
period report triggered; FER event report triggered.
The uplink open loop power control algorithm is executed in the RNC
while the downlink one is executed in the UE.
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Power Control
Handover Control
Compressed Mode
Admission Control
Load Control
Code Allocation Spreading
Radio Resource Management
秘密▲
Purpose of Handover Control
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When UE is mov ing from the coverage area of one si te to
another si te, or th e qual i ty of s erv ice is decl ined by external
inter ference dur ing a cal l, the cal l mus t be handed o ver to an idle
channel for sustain ing the serv ice. Handover is a key techn ology
for m obi le network ing
Purpose of Handover Control
秘密▲
Handover Types
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Handover Types
Soft Handover
Intra-Node B soft handover (Softer Handover)
Inter-Node B soft handover
Inter-RNC soft handover (involving Iur interface)
Hard Handover
Inter-frequency hard handover
Intra-frequency hard handover (forced hard handover)
Inter-RAT hard handover (between different Radio Access
Technology, e.g. WCDMA and GSM)
Inter-mode handover (e.g. between FDD and TDD)
秘密▲
Handover Demonstration
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Handover Demonstration
Hard
Handover
Soft
Handover
秘密▲
Soft Handover/Softer Handover
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A
B
C
A
B
C
A
B
C
A
B
C
A
B
C
A
B
C
秘密▲ WCDMA General Handover Procedures
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Measurement Control
UTRAN demands the UE to start measurement through issuing a
measurement control message.
Handover decision
UTRAN makes the decision based on the measurement reports
from UE. The implementation of handover decision is various for
different vendors. It impacts on the system performance critically.
Handover execution
UTRAN and UE execute different handover procedure according to
the handover command.
秘密▲ Handover Flows
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(A) RNC sends
measurement control
message to UE (MeasurementControl)
(B) UE starts measurement
task with the parameters
included in the message,
and reports measurement
results(Measurement
Report)
(C) RNC stores the
measurement results
according to frequencies and
cells
(D) RNC Estimates the
quality of each carrier
(including intra-frequency
and inter-frequency)
(E) Quality
Decision
(G) Allocate
resource in target
cell of the virtual
active set, prepare
to execute handover
(F) maintain
the active set
and monitored
set
(H) Allocate
resource in target
cell, prepare to
execute handover
Currentcarrier has
good quality
Othersystem
has good
qualityOther carrier has
good quality
(I)If handover is required, RNC sends
handover command with target cell to UE
秘密▲
General Procedure of Handover Control (I)
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General Procedure of Handover Control (I)
Measuring
The measurement objects are decided by RNC. Usually, either
Ec/N0 or RSCP (Received Signal Code Power) of P-CPICH channel
is used for handover decision.
ZTE RNC adopts Ec/N0 measurement, because Ec/N0
embodies both the received signal strength and the interference.
The relation of Ec/N0 and RSCP is shown as follows:
Ec/N0 =RSCP/RSSI
In the above equation,RSSI(Received Signal Strength
Indicator )is measured within the bandwidth of associated channels
秘密▲
General Procedure of Handover Control (II)
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General Procedure of Handover Control (II)
FilteringThe measurement results should be filtered before being
reported. Measurement filtering can be regarded as a low pass
filtering procedure.
The following equation is applied for filtering
Fn=(1-a)Fn-1+a*Mn
Variants definition:
Fn:filtered measurement result;
Fn-1:last filtered measurement result;
Mn:latest Ec/I0 or RSCP measurement result received from physical
layer;
a = 1/2(k/2), k means the ―Filter coefficient‖, which is included in the
Measurement Control message. It is decided by the UTRAN.
F0 is initialized by the first measurement result M1.
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General Procedure of Handover Control (III)
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Reporting
Period report triggered handover
Event report triggered handover
Base on the filtered measurement result
Base on the event
Soft
Handover
Hard
Handover
Period
Event
Measurement result filtered in UE
Event decided in RNC
Handover decided in RNC
Measurement result filtered in UE
Event decided in UE
Handover decided in RNC
General Procedure of Handover Control (III)
秘密▲
General Procedure of Handover Control (IV)
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General Procedure of Handover Control (IV)
Handover algorithm All the handover algorithms including soft handover,
hard handover and so on are implemented on the
event decision made from measurement report.
Events defined in 3GPP specifications
Intra-frequency events:1A~1F
Inter-frequency events:2A~2F
Inter-RAT events:3A~3D
秘密▲
Concepts Related to Handover
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p
Active Set: A set of cells that have established radio links with a
certain mobile station. User information is sent from all these
cells.
Monitored Set: A set of cells that are not in the active set but are
monitored according to the list of adjacent cells assigned by the
UTRAN.
Detected Set: A set of cells that are neither in the active set nor
in the monitor set
秘密▲
An Example of Handover Procedure
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An Example of Handover Procedure
Pilot Ec/Io of cell 1
time
Pilot
Ec/Io
Connect to cell1 Event 1A Event 1C Event 1B
(add cell2)(replace cell1 with cell 3)(remove cell3)
Pilot Ec/Io of cell 2
Pilot Ec/Io of cell 3
⊿t ⊿t ⊿t
秘密▲
RNS Relocation
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RNS Relocation
Core NetworkCore Network
Service
RNSTarget
RNS
Service
RNSTarget
RNS
Iu Iu
Iur
RNS
Radio Network Sub-system
RNS relocation can : Reduce the Iur traff ic signif icant ly
Enhance the sys tem adaptabi l i ty
秘密▲
Hard Handover
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Hard Handover
Hard handover measurement is much more complex for UE
than soft handover measurement.
Inter-frequency hard handover requires UE to measure the
signal of other frequency.
WCDMA employs compressed mode technology to support
inter-frequency measurement.
秘密▲
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Power Control
Handover Control
Compressed Mode
Admission Control
Load Control
Code Allocation Spreading
Radio Resource Management
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秘密▲
Compressed Mode
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Compressed Mode
Compressed Mode Transm ission Diagram
Transmit gaps(Maximum 7 slots = 4.7ms) 1 frame(10ms)
10ms
秘密▲
Generation of Compressed Mode Frame
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p
Puncturing Lower the symbol rate of physical channel when
processing the rate matching procedure
SF halving Employ half SF, e.g. employ SF64 to replace SF128
High layer scheduling Decrease the bit rate from up layer
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Power Control
Handover Control
Compressed Mode
Admission Control
Load Control
Code Allocation Spreading
Radio Resource Management
秘密▲
Admission Control
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The admission control is employed to admit
the access of incoming call. Its general
principal is based on the availability and
utilization of the system resources.
If the system has enough resources such as
load margin, code, and channel element etc.
the admission control will accept the call and
allocate resources to it.
秘密▲ Purpose of Admission Control
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The admission control should implement admission or rejection
for the new users, new RAB and new RL (for example handover)according to the current resource situation. The admission
control will sustain the system stability firstly and try the best to
satisfy the new calling service QoS request, such as service rate,
quality (SIR or BER), and delay etc., basing on the radio
measurement.
秘密▲ Admission Control in Uplink
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I total_old +ΔI >I threshold
The current RTWP (Received
Total Wide Power) value of cell,
which is reported by Node B
Access
Threshold
Interference capacityService priority
Reserved capacity for
handover
I own-
cell
0
~ N
I other- cell
The forecasted interference including the deltainterference brought by the incoming service is
calculated by the admission algorithm, and its
result depends on the QoS and transmission
propagation environment
秘密▲
Admission Control in Uplink
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Admission Control in Uplink
Different ultimate user numbers Different interference threshold under different ultimate
user number conditions
Different ultimate throughputs
Quantity of Subscriber
Quantity of Subscriber-- The Total Bandwidth Received by Node B
T h e T o t a l B a n d
w i d t h P o w e r R e c e i v e d b y N o d e B ( d B m )
Ultimate Situation for different service rate
Throughput
Throughput -- The Total Bandwidth Received by Node B
T h e T o t a l B a n d w
i d t h P o w e r R e c e i v e d b y N o d e B ( d B m )
秘密▲ Admission Control in Downlink
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P total_old + △P>=P threshold
Access
Threshold
The forecasted TCP value including deltapower required for the incoming service is
calculated by the admission algorithm, and its
result depends on the QoS and transmission
propagation environment.
The current TCP value of cell, which
is reported by Node B
(Transmitted Carrier Power*Pmax)
Max TCP of cell
Service priority
Reserved capacity for
handover
秘密▲
Admission Control in Downlink
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Quantity of Subscriber
T h e T o t a l T r a n s m i s s i o n P o w e r ( d B m )
Red:
low speed serviceBlue:high speed service
The above figure illustrates the relation between ultimate user
number corresponds to different service rate and distance
under equidistant distribution condition
秘密▲ Admission Control Analysis
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The service can be either one-direction or bi-direction
type. For bi-direction service, it is admitted only afterboth uplink and downlink are admitted.
Admission control is the only access entry for the
incoming services, its strategy will directly effect thecell capacity and stability, e.g. call loss rate, call drop
rate.
秘密▲
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Power Control
Handover Control
Compressed Mode
Admission Control
Load Control
Code Allocation Spreading
Radio Resource Management
秘密▲
Purpose of Load Control
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Load controlThe purpose of load control is to keep thesystem load under a pre-planned threshold
through decreasing the load in several ways,
therefore to improve the system stability.
The speed and
position changing of
UE may worsen the
wireless environment.
Increasing of
transmitted power
will increase the
system load
秘密▲ 荷Load Control Flows
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Start
Decision Light load Over load
Normal load
1. Handover in and access
are forbidden
2. TCP increasing isforbidden
3. RAB service rate degrade
4. Handover out
5. Release call
1. Handover in and
access are allowed
2. Transmitted code
power (TCP) increasing
is allowed
3. RAB service rate
upgrade is allowed
1. Handover in
and access are
allowed2. TCP
increasing is
allowed
秘密▲ Load Control in Uplink
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Triggers
RTWP (Received Total Wind-band Power) value frommeasurement report exceeds the uplink overload threshold;
Admission control triggers when rejecting the high priority service’s
access due to insufficient load capacity in uplink.
Methods for decreasing load Decrease the target Eb/N0 of service in uplink;
Decrease the rate of none real time data service;
Handover to GSM system;
Decrease the rate of real time service, e.g. voice call;
Release calls.
Methods for increasing load Increase the service rate.
秘密▲ Load Control in Downlink
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Triggers
TCP (Transmitted Carrier Power) value from measurement reportexceeds the downlink overload threshold;
Admission control triggers when denying the high priority service’s
access due to insufficient load capacity in downlink.
Methods for decreasing load
Decrease the downlink target Eb/N0 of service in downlink;
Decrease the rate of none real time data service;
Handover out to coverage-shared light loaded carrier;
Handover out to GSM system;
Decrease the rage of real time service, e.g. voice call;
Release calls.
Methods for increasing load
Increase the service rate.
秘密▲ Cell Breathing
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Cell breathing isone of the means
for load control
The purpose of cell breathing is to share the load of hot-
spot cell with the light loaded neighbor cells, therefore to
improve the utilization of system capacity.
秘密▲
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Power Control
Handover Control
Compressed Mode
Admission Control
Load Control
Code Allocation Spreading
Radio Resource Management
秘密▲ Purpose of Code Resource Planning
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WCDMA system adopts primary scrambling code to distinguish
the cells and channel code to distinguish physical channels indownlink, and adopts scrambling code to distinguish users in
uplink. The OVSF (Orthogonal Variable Spreading Factor) code
tree is a sparse resource and only one tree can be used in each
cell. In order to make full use of the capacity, and support as
many connections as possible, it is important to plan and controlthe usage of channel code resource.
Although the uplink scrambling codes are sufficient, the RNC
should plan to use the codes for avoiding allocating same code
to different users in inter-RNC handover scenario.
秘密▲ Code Resource Planning
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Code types in WCDMA system
Uplink Scrambling Code
Uplink Channel Code
Downlink Scrambling Code
Downlink Channel Code
The uplink scrambling code and downlink scrambling code can
be planned easily, and uplink channel code does not need
planning, therefore, only the downlink channel code is planned
with certain algorithm in RNC.
Each cell has one primary scrambling code, which correlates
with a channel code tree. The downlink channel code tree is a
typical binary tree with each layer corresponds to a certain SF
ranging from SF4 to SF512.
秘密▲ Generation of Channel Code
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SF = 1 SF = 2 SF = 4
Cch,1,0 = (1)
Cch,2,0 = (1,1)
Cch,2,1 = (1,-1)
Cch,4,0 =(1,1,1,1)
Cch,4,1 = (1,1,-1,-1)
Cch,4,2 = (1,-1,1,-1)
Cch,4,3 = (1,-1,-1,1)
秘密▲ OVSF Code Tree
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秘密▲
Channel Code Characters
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SF=8
SF=32
SF=16
Code allocation restriction:
The code to be allocated must fulfill the condition that its ancestor nodesincluding from father node to root node and offspring nodes in the sub tree
are not allocated;
Code allocation side effect:
The allocated node will block its ancestor nodes and offspring nodes, thus
the blocked nodes will not be available for allocation until being unblocked.
秘密▲ Strategy of Channel Code Allocation
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Full utilization
The fewer the blocked codes, the higher the code tree
utilization rate.
Low Complexity
Short code first
Allocate codes for common channels and physical shared
channels prior to dedicated channels.
Guarantee the code allocation for common physical channels.
Apply certain optimized strategy to allocate codes for
downlink dedicated physical channels.
秘密▲ An Example of Code Allocation
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0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
SF = 4
SF = 8
SF = 16
SF = 32
SF = 4
SF = 8
SF = 16
SF = 32
Red circles represent the codes that have been allocated;
Green circles represent the codes that are blocked by the allocated offspring codes;
Blue circles represent the codes that are blocked by the allocated ancestor codes;
Black circles represent the codes that are to be allocated;
Choose one
code from
three
candidates
秘密▲
Contents
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WCDMA System Overview
WCDMA Wireless Principle A
WCDMA Key Technology
WCDMA Capacity Feature
Radio Resource Management
WCDMA Key Technology
秘密▲
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RAKE Receiver
Multi-User Detection (MUD)
WCDMA Key Technology
秘密▲ RAKE Receiver
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d
d
2
d
3
RAKE Receiver can effectively overcome the multi-path
interference, consequently improve the receiving performance.
The multi-path signals contain some useful energy , therefore
the CDMA receiver can combine these energy of multi-path
signals to improve the received signal to noise ratio.
RAKE receiver adopts several correlation detectors to receive
the multi-path signals, and then combines the received signal
energy.
秘密▲ RAKE Receiver
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Single path
receiving circuit
Single path
receiving circuit
Single path
receiving circuit
Multi-path search
engine
Calculate signal
strength and
delay
Combiner Combined
Signal
tt
s(t) s(t)
Receiver
秘密▲
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RAKE Receiver
Multi-User Detection (MUD)
WCDMA Key Technology
秘密▲ Multi-User Detection
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WCDMA telecommunication system can provide communicationenvironment for simultaneous multi-user access. The research
result indicates that multi-access interference and channel noise
have different statistical characters.
Multi-access interference has the estimable and reproducible
features.
The purpose of MUD is to reduce the multi-access interference
till 0 through collecting the useful information of all users and
adopting certain signal processing method.
秘密▲ Multi-User Detection Technology
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The CDMA receiver is based on the principal of RAKE receiving, and
the interference from other users is treated as noise.
The capacity of RAKE receiving based CDMA system is interferencelimited.
The true optimal receiver adopts join-detection technology to detect all
the received signals, and removes the interference from other users.
Multi-User Detection (MUD), also named as Join-detection or
Interference-elimination,can reduce the multi-access interference,thereby improve the capacity.
MUD can eliminate the near-far effect.
The near optimal MUD receiver and interference eliminated receiver
are actually applied instead of the true optimal MUD receiver because
of the implementation complexity.
秘密▲ True Optimal Multi-User Detection
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The true optimal detection consists of K matched filters and one
Viterbi algorithm implementation. The complexity has an exponents relation to the user number.
Matched Filter 1
Synchronize
Z1(
i)
Matched Filter 2Z2(i)
Matched Filter kZk (i)
Viterbi
Algorithm
Implementation
b1(
i)
b2(i)
bk (i)
r(t)
Synchronize
Synchronize
秘密▲ Linear De-correlation Detection
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De-correlation detection transforms the multi-access
interference, which is generated in multi-user environment, intoan equivalent transmission response matrix,i.e. the channel
codes correlation matrix R。
The complexity has an exponents relation to the user number.
Matched Filter 1
Matched Filter 2
Matched Filter k
Linear
Transform
ation
R -1
b1
b2
bk
r(t)
Bit Decision
Bit Decision
Bit Decision
秘密▲ Summary
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WCDMA Wireless Technology
Spreading Channel Coding (Convolutional Coding, Turbo coding)
Interleaving
Diversity
WCDMA Radio Resource Management RRM)
Power Control
Handover Control
Admission Control
Load Control
Code Allocation WCDMA Key Technology
RAKE Receiver
MUD
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