01-Owa200002 Wcdma Ran Fundamental Issue1.1
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Transcript of 01-Owa200002 Wcdma Ran Fundamental Issue1.1
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Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
WCDMA RAN Fundamental
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Objectives
Upon completion of this course, you will be able to:
Describe feature of wireless propagation
Outline the advantage of CDMA principle
Characterize code sequence
Outline the fundamentals of RAN
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Contents
1. 3G Overview
2. CDMA Principle
3. WCDMA Fundamental
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Contents
1. 3G Overview
2. CDMA Principle
3. WCDMA Fundamental
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Different Service, Different Technology
AMPS
TACS
NMT
Others
1G 1980sAnalog
GSMGSM
CDMA CDMA IS-95IS-95
TDMATDMAIS-136IS-136
PDCPDC
2G 1990sDigital
Technologies drive
3G IMT-2000
UMTSUMTSWCDMAWCDMA
cdmacdma20002000
Demands drive
TD-SCDMA
TD-SCDMA
3G provides compositive services for both operators and subscribers
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3G Evolution
Proposal of 3G IMT-2000: the general name of third generation mobile com
munication system The third generation mobile communication was first propo
sed in 1985 , and was renamed as IMT-2000 in the year of 1996
Commercialization: around the year of 2000 Work band : around 2000MHz The highest service rate :up to 2000Kbps
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3G Objectives
3G is developed to achieve: Universal frequency band for standard and seamless global
coverage High spectral efficiency High quality of service with complete security and reliability Easy and smoothly transition from 2G to 3G, compatible with
2G Provide multimedia services, with the rates:
Vehicle environment: 144kbps Walking environment: 384kbps Indoor environment: 2Mbps
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1850 1900 1950 2000 2050 2100 2150 2200 2250
ITU
Europe
USA MSSPCS
A D B BC D CE F A FE MSSReserveBroadcast auxiliary
2165 MHz1990 MHz
1850 1900 1950 2000 2050 2100 2150
2200 2250
1880 MHz 1980 MHz
UMTSGSM 1800 DECT MSS
1885 MHz 2025 MHz
2010 MHz
IMT 2000
MSSUMTS
Japan MSSIMT 2000MSSIMT 2000PHS
1895
1918
BC
1885
A A’
2170 MHz
IMT 20002110 MHz 2170 MHz
MSS MSS
CDMATDDWLL
FDDWLL
1980
2025MHz
GSM1800
CDMAFDDWLL
1960
1920
1945
China
cellular(1) cellular(2) cellular(2)
1805 MHz
1865
1865
1870
1885
1890
1895
1910
1930
1945
1965
1970
1975
3G Spectrum Allocation
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Bands WCDMA Used Main bands
1920 ~ 1980MHz / 2110 ~ 2170MHz Supplementary bands: different country maybe different
1850 ~ 1910 MHz / 1930 MHz ~ 1990 MHz (USA) 1710 ~ 1785MHz / 1805 ~ 1880MHz (Japan) 890 ~ 915MHz / 935 ~ 960MHz (Australia)
Frequency channel number = central frequency×5, for main band:
UL frequency channel number : 9612 ~ 9888 DL frequency channel number : 10562 ~ 10838
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3G Application Service
Time Delay
BER
background
conversational
streaming
interactive
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WCDMA Protocol Version Evolution
3GPP Rel993GPP Rel4
3GPP Rel5
2000 2001 2002
GSM/GPRS CN
WCDMA RTT
IMSHSDPA 3GPP Rel6
MBMSHSUPA
2005
CS domain change to NGN
WCDMA RTT
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WCDMA System Architecture
RNS
RNC
RNS
RNC
Core Network
Node B Node B Node B Node B
Iu-CS Iu-PS
Iur
Iub IubIub Iub
CN
UTRAN
UEUu
CS PS
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Contents
1. 3G Overview
2. CDMA Principle
3. WCDMA Fundamental
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Multiple Access and Duplex Technology Multiple Access Technology
Frequency division multiple access (FDMA)
Time division multiple access (TDMA)
Code division multiple access (CDMA)
Duplex Technology
Time division duplex (TDD)
Frequency division duplex (FDD)
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Multiple Access Technology
frequency
time
power
FDMA
frequencytime
power
TDMA
power
time
CDMA
frequency
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Duplex Technology
Time
Frequency
Power
TDD
USER 2
USER 1
DL
ULDL
DL
UL
FDD
Time
Frequency
Power
UL DL
USER 2
USER 1
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Contents
1. 3G Overview
2. CDMA Principle
3. WCDMA Fundamental
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Processing Procedure of WCDMA System
SourceCoding
Channel
CodingSpreading Modulation
SourceDecodin
g
ChannelDecodin
g
Despreading
Demodulation
Transmission
Reception
chip modulated signalbit symbol
Service
Signal
Radio Channel
Service
Signal
Transmitter
Receiver
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WCDMA Source Coding
AMR (Adaptive Multi-Rate) Speech
A integrated speech codec with 8
source rates.
The AMR bit rates can be controlled
by the RAN depending on the system
load and quality of the speech
connections.
Video Phone Service
H.324 is used for VP Service in CS
domain.
Includes: video codec, speech codec,
data protocols, multiplexing and etc.
CODEC Bit Rate
(kbps)
AMR_12.2
0
12.2 (GSM
EFR)
AMR_10.2
0
10.2
AMR_7.95 7.95
AMR_7.40 7.4 (TDMA
EFR)
AMR_6.70 6.7 (PDC EFR)
AMR_5.90 5.9
AMR_5.15 5.15
AMR_4.75 4.75
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WCDMA Channel Coding
Effect
Enhance the correlation among symbols so as to recover the signal
when interference occurs
Provides better error correction at receiver, but brings increment of
the delay
Types
No Coding
Convolutional Coding (1/2, 1/3)
Turbo Coding (1/3)
Code Block of N Bits
No Coding
1/2 Convolutional Coding
1/3 Convolutional Coding
1/3 Turbo Coding
Uncoded N bits
Coded 2N+16 bits
Coded 3N+24 bits
Coded 3N+12 bits
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WCDMA Interleaving
Effect Interleaving is used to reduce the probability of consecutive bits error
Longer interleaving periods have better data protection with more delay
1110
1.........
............
...000
0100
0 0 1 0 0 0 0 . . . 1 0 1 1 1
1110
1.........
............
...000
00100 0 … 0 1 0 … 1 0 0 … 1 0 … 1 1
Inter-column permutation
Output bits
Input bits
Interleaving periods: 10, 20, 40, or 80 ms
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WCDMA Channelization Code
OVSF Code (Orthogonal Variable Spreading Factor)
SF = chip rate / symbol rate High data rates → low SF code
Low data rates → high SF code
SF = 8SF = 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)
Cch,8,0 = (1,1,1,1,1,1,1,1)
Cch,8,1 = (1,1,1,1,-1,-1,-1,-1)
Cch,8,2 = (1,1,-1,-1,1,1,-1,-1)
Cch,8,3 = (1,1,-1,-1,-1,-1,1,1)
Cch,8,4 = (1,-1,1,-1,1,-1,1,-1)
Cch,8,5 = (1,-1,1,-1,-1,1,-1,1)
Cch,8,6 = (1,-1,-1,1,1,-1,-1,1)
Cch,8,7 = (1,-1,-1,1,-1,1,1,-1)
……
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Process Gain
Process Gain
Process gain differs for each service.
If the service bit rate is greater, the process gain is
smaller, UE needs more power for this service, then
the coverage of this service will be smaller, vice versa.
)rate bit
rate chiplog(10Gain ocessPr
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Purpose of Channelization Code For uplink, Channelization code ( OVSF code ) is used to separate
different physical channels of one connection
For downlink, Channelization code ( OVSF code ) is used to separate different connections in a cell
Radio bearer** SF Radio bearer** SF
Speech 4.75 UL 128 Speech 4.75 DL 256
Speech 12.2 UL 64 Speech 12.2 DL 128
Data 64 kbps UL 16 Data 64 kbps DL 32
Data 128 kbps UL 8 Data 128 kbps DL 16
Data 144 kbps UL 8 Data 144 kbps DL 16
Data 384 kbps UL 4 Data 384 kbps DL 8
Data 2048 kbps UL 4 Data 2048 kbps DL 8
Speech 12.2 + Data 64 kbps UL 16 Speech 12.2 + Data 64 kbps DL
32
** With 3.4 kbps Signaling
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Correlation
Correlation measures similarity between any two arbitrary signals.
Identical and Orthogonal signals:
Correlation = 0Orthogonal signals
-1 1 -1 1
-1 1 -1 1
1 1 1 1
+1
-1
+1
-1
+1
-1
+1
-1
Correlation = 1Identical signals
-1 1 -1 1
1 1 1 1
-1 1 -1 1
C1
C2
+1
+1
C1
C2
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Orthogonal Code Usage - Coding
UE1: + 1 - 1
UE2: - 1 + 1
C1 : - 1 + 1 - 1 + 1 - 1 + 1 -1 + 1
C2 : + 1 + 1 + 1 + 1 + 1 + 1 +1 + 1
UE1×c1 : - 1 + 1 - 1 + 1 + 1 - 1 +1 - 1
UE2×c2 : - 1 - 1 - 1 - 1 + 1 + 1 +1 + 1
UE1×c1 + UE2×c2 : - 2 0 - 2 0 + 2 0 + 2 0
UE1: + 1 - 1
UE2: - 1 + 1
C1 : - 1 + 1 - 1 + 1 - 1 + 1 -1 + 1
C2 : + 1 + 1 + 1 + 1 + 1 + 1 +1 + 1
UE1×c1 : - 1 + 1 - 1 + 1 + 1 - 1 +1 - 1
UE2×c2 : - 1 - 1 - 1 - 1 + 1 + 1 +1 + 1
UE1×c1 + UE2×c2 : - 2 0 - 2 0 + 2 0 + 2 0
Page28Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
Orthogonal Code Usage - Decoding
UE1×C1 + UE2×C2: - 2 0 - 2 0 + 2 0 + 2 0
UE1 Dispreading by c1: - 1 + 1 - 1 + 1 - 1 + 1 - 1 + 1
Dispreading result: + 2 0 + 2 0 - 2 0 - 2 0
Integral judgment: + 4 (means + 1) - 4 (means - 1)
UE2 Dispreading by c2: + 1 + 1 + 1 + 1 + 1 + 1 + 1 + 1
Dispreading result: - 2 0 - 2 0 + 2 0 + 2 0
Integral judgment: - 4 (means - 1) + 4 (means+ 1)
UE1×C1 + UE2×C2: - 2 0 - 2 0 + 2 0 + 2 0
UE1 Dispreading by c1: - 1 + 1 - 1 + 1 - 1 + 1 - 1 + 1
Dispreading result: + 2 0 + 2 0 - 2 0 - 2 0
Integral judgment: + 4 (means + 1) - 4 (means - 1)
UE2 Dispreading by c2: + 1 + 1 + 1 + 1 + 1 + 1 + 1 + 1
Dispreading result: - 2 0 - 2 0 + 2 0 + 2 0
Integral judgment: - 4 (means - 1) + 4 (means+ 1)
Page29Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
Spreading and DespreadingDesired signal
Other user’s signal
Desired spreadingsignal
Spreading code
Data after despreading
Other spreading signal
Other signal after integration
1
-1
1
-1
1
-1
8
-8
1-1
8-8
Data after integration
Other signal after despreading
Correlation at a CDMA receiver
Correlation with incorrect code
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Spectrum Analysis of Spreading & Dispreading
Spreading code
Spreading code
Signal Combination
Narrowband signal
f
P(f)
Broadband signal
P(f)
f
Noise & Other Signal
P(f)
f
Noise+Broadband signal
P(f)
f
Recovered signal
P(f)
f
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Spectrum Analysis of Spreading & Dispreading
Max allowed interference
Eb/No Requirement
Power
Max interference caused by UE
Processing Gain
Ebit
Interference from other UE Echip
Eb / No = Ec / Io ×PG
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Purpose of Scrambling Code
Scrambling code is used to distinguish different
transmitters
For downlink, Scrambling code is used to separate
different cells
For uplink, scrambling code is used to separate
different UE
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Scrambling Code
Scrambling code: GOLD sequence.
There are 224 long uplink scrambling codes which are
used for scrambling of the uplink DPCCH/DPDCH. Uplink
scrambling codes are assigned by higher layers.
For downlink physical channels, 8192 scrambling codes
are used.
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Code Multiplexing
Downlink Transmission on a Cell Level
Scrambling codeScrambling code
Channelization code 1Channelization code 1
Channelization code 2Channelization code 2
Channelization code 3Channelization code 3
User 1 signal
User 2 signal
User 3 signal
NodeB
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Code Multiplexing
Uplink Transmission on a Cell Level
NodeB
Scrambling code 3
User 3 signal
Channelization code
Scrambling code 2
User 2 signal
Channelization code
Scrambling code 1
User 1 signal
Channelization code
Page36Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
Modulation Overview
1 00 1
time
Basic steady radio wave:
carrier = A.cos(2Ft+)
Amplitude Shift Keying:
A.cos(2Ft+)
Frequency Shift Keying:
A.cos(2Ft+)
Phase Shift Keying:
A.cos(2Ft+)
Data to be transmitted:Digital Input
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Modulation Review
Digital Modulation - QPSK
-1 -1
1 102 3 4 9875 6
1 102 3 4 9875 6
NRZ Input
I di-Bit Stream
Q di-Bit Stream
IComponent
QComponent
QPSK Waveform
1
1
-1
1
-1
1
1
-1
-1
-1
1 1 -1 1 -1 1 1 -1
Page38Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
Modulation Review
NRZ coding
90o
NRZ coding
QPSK
Q(t)
I(t)
fo
±A
±A ±Acos(ot)
±Acos(ot + /2)
1 1 /4
1 -1 7/4
-1 1 3/4
-1 -1 5/4
)cos(2: oAQPSK
Page39Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
Demodulation
QPSK Constellation Diagram
1 102 3 4 9875 6
QPSK Waveform
1,1
-1,-1
-1,1
1,-1
1 -11 -1 1 -1-11-1 1
-1,1
NRZ Output
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Wireless Propagation
ReceivedSignal
TransmittedSignal
Transmission Loss:Path Loss + Multi-path Fading
Time
Amplitude
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Propagation of Radio SignalSignal at Transmitter
Signal at Receiver
-40
-35
-30
-25
-20
-15
-10
-5
dB
0
0
dB
m
-20
-15
-10
-5
5101520
Fading
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Fading Categories
Fading Categories
Slow Fading
Fast Fading
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Diversity Technique
Diversity technique is used to obtain uncorrelated signals for combining
Reduce the effects of fading Fast fading caused by multi-path
Slow fading caused by shadowing
Improve the reliability of communication
Increase the coverage and capacity
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Diversity
Time diversity
Channel coding, Block interleaving
Frequency diversity
The user signal is distributed on the whole bandwidth frequency
spectrum
Space diversity
Receive space diversity
Transmit space diversity
Polarization diversity
Vertical polarization
Horizontal polarization
Page45Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
Principle of RAKE Receiver
Receive set
Correlator 1
Correlator 2
Correlator 3
Searcher correlator
Calculate the time delay and signal strength
CombinerThe
combined signal
tt
s(t) s(t)
RAKE receiver help to overcome on the multi-path fading and enhance the receive performance of the system
Page46Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
Principle of RAKE Receiver
The RAKE receiver take advantage of multi-path diversity
The RAKE receiver processes the received signal
Identify the time delay positions at which significant energy arrives
Allocate correlation receivers (RAKE fingers) to those peaks
Within each Rake finger, track the fast-changing phase and
amplitude values
Adjust the phase, remove the values originating from fast-fading
Combine the demodulated and phase-adjusted symbols across all
active fingers
Present them to the decoder for further processing
This processing is called Maximal Ratio Combining
Page47Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
Summary
In this course, we have discussed basic concepts of WCDMA: Spreading / Despreading principle UTRAN Voice Coding UTRAN Channel Coding UTRAN Spreading Code UTRAN Scrambling Code UTRAN Modulation UTRAN Transmission/Receiving
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