WCDMA RAN Fundamental
Page1
Objectives
Upon completion of this course, you will be able to:
Know the development of 3G
Outline the advantage of CDMA principle
Characterize code sequence
Outline the fundamentals of RAN
Describe feature of wireless propagation
Page2
Contents
3G Overview
CDMA Principle
WCDMA Fundamental
Page3
Contents
3G Overview
CDMA Principle
WCDMA Fundamental
Page4
Different Service, Different Technology
AMPS
TACS
NMT
Others
1G 1980s
Analog
GSM
CDMA
IS-95
TDMA
IS-136
PDC
2G 1990s
Digital
Technologies
drive
3G
IMT-2000
UMTS
WCDMA
cdma
2000
Demands
drive
TD-
SCDMA
3G provides compositive services for both operators and subscribers
Page5
Different Service, Different Technology
AMPS
TACS
NMT
Others
1G 1980s
Analog
GSM
CDMA
IS-95
TDMA
IS-136
PDC
2G 1990s
Digital
Technologies
drive
3G
IMT-2000
UMTS
WCDMA
cdma
2000
Demands
drive
TD-
SCDMA
3G provides compositive services for both operators and subscribers
Page6
3G Evolution
Proposal of 3G
IMT-2000: the general name of third generation mobile communication system
The third generation mobile communication was first proposed 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 Spectrum Allocation
Page8
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
Page10
The Core technology of 3G: CDMA
CDMA


WCDMA
CN: based on MAP and GPRS
RTT: WCDMA - FDD/TDD

TD-SCDMA
CN: based on MAP
RTT: TD-SCDMA

cdma2000
CN: based on ANSI 41 and MIP
RTT: cdma2000
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WCDMA Protocol Version Evolution
3GPP Rel99
3GPP Rel4
3GPP Rel5
2000
2001
2002
GSM/GPRS CN
WCDMA RTT
IMS
HSDPA
3GPP Rel6
MBMS
HSUPA
2005
CS domain change to NGN
WCDMA RTT
Page12
WCDMA System Architecture
Page13
Protocol Mode for UTRAN Terrestrial Interface
The structure is based on the principle that the layers and planes are logically independent of each other.
Page14
Contents
3G Overview
CDMA Principle
WCDMA Fundamental
Page15
Multiple Access and Duplex Technology
Multiple Access Technology
Frequency division multiple access (FDMA)
Time division multiple access (TDMA)
Code division multiple access (CDMA)
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Multiple Access Technology
Page17
Multiple Access and Duplex Technology
Duplex Technology
Frequency division duplex (FDD)
Time division duplex (TDD)
Page18
Duplex Technology
Page19
Contents
3G Overview
CDMA Principle
WCDMA Fundamental
Page20
Processing Procedure of WCDMA System
Page21
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.
Page22
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.
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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)
Page24
WCDMA Interleaving
Effect
Interleaving is used to reduce the probability of consecutive bits error
Longer interleaving periods have better data protection with more delay
0 0 1 0 0 0 0 . . . 1 0 1 1 1
0 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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Correlation
Correlation measures similarity between any two arbitrary signals.
Identical and Orthogonal signals:
Correlation = 0
Orthogonal signals
-1 1 -1 1

-1 1 -1 1

1 1 1 1
+1

-1
+1

-1
+1

-1
+1

-1
Correlation = 1
Identical 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
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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)
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Spectrum Analysis of Spreading & Dispreading
Page29
Spectrum Analysis of Spreading & Dispreading
Power
Echip
Eb / No = Ec / Io ×PG
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Spreading Technology
Spreading consists of 2 steps
Channelization operation, which transforms data symbols into chips
Scrambling operation is applied to the spreading signal
Data bit
OVSF
code
Scrambling code
Chips after spreading
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WCDMA Channelization Code
OVSF Code (Orthogonal Variable Spreading Factor) is used as channelization code
Page32
WCDMA Channelization Code
SF = chip rate / symbol rate
High data rates → low SF code
Low data rates → high SF code
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Purpose of Channelization Code
Channelization code is used to distinguish different physical channels of one transmitter
For downlink, channelization code ( OVSF code ) is used to separate different physical channels of one cell
For uplink, channelization code ( OVSF code ) is used to separate different physical channels of one UE
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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.
In UMTS, Gold codes were chosen for their very low peak cross-correlation.
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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Downlink Scrambling Code
Page37
Primary Scrambling Code Group
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Code Multiplexing
Downlink Transmission on a Cell Level
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Code Multiplexing
Uplink Transmission on a Cell Level
Page40
Modulation Overview
Page41
Modulation Overview
Digital Modulation - BPSK
Page42
Modulation Overview
Digital Modulation - QPSK
Page43
Modulation Overview
Page44
Demodulation
QPSK Constellation Diagram
1
10
2
3
4
9
8
7
5
6
QPSK Waveform
1,1
-1,-1
-1,1
1,-1
1
-1
1
-1
1
-1
-1
1
-1
1
-1,1
NRZ Output
Page45
WCDMA Modulation
Different modulation methods corresponding to different transmitting abilities in air interface
HSDPA: adopt 16QAM
R99/R4: adopt QPSK
Page46
Wireless Propagation
Page47
Propagation of Radio Signal
Signal at Transmitter
Signal at Receiver
-40
-35
-30
-25
-20
-15
-10
-5
dB
0
0
dBm
-20
-15
-10
-5
5
10
15
20
Page48
Fading Categories
Fading Categories
Slow Fading
Fast Fading
Page49
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
Page51
Principle of RAKE Receiver
Receive set
Correlator 1
Correlator 2
Correlator 3
Searcher correlator
Calculate the time delay and signal strength

Combiner
The combined signal
t
t
s(t)
s(t)
RAKE receiver help to overcome on the multi-path fading and enhance the receive performance of the system
Page52
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