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WCDMA Principle
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Objectives
Upon completion of this course, you will be able to:
Describe the development of 3G
Outline the advantage of CDMA principle
Characterize code sequence
Outline the fundamentals of RAN
Describe feature of wireless propagation
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Contents
3G Overview
CDMA Principle
WCDMA Network Architecture and protocol structure
WCDMA Wireless Fundamental
Physical Layer Overview
Physical Channels
Physical Layer Procedure
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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
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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
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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
Error Ratio
background
conversational
streaming
interactive
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The Core technology of 3G: CDMA
CDMA
WCDMA CN: based on MAP and GPRS
RTT: WCDMA
TD-SCDMA CN: based on MAP and GPRS
RTT: TD-SCDMA
cdma2000 CN: based on ANSI 41 and MIP
RTT: cdma2000
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Contents
3G Overview
CDMA Principle
WCDMA Network Architecture and protocol structure
WCDMA Wireless Fundamental
Physical Layer Overview
Physical Channels
Physical Layer Procedure
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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)
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Multiple Access Technology
Power
FDMA
Power
TDMA
Power
CDMA
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Multiple Access and Duplex Technology
Duplex Technology
Frequency division duplex (FDD)
Time division duplex (TDD)
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Duplex Technology
Time
Frequency
Power
TDD
USER 2
USER 1
DL UL
DL DL
UL
FDD
Time
Frequency
Power
UL DL
USER 2
USER 1
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Contents
3G Overview
CDMA Principle
WCDMA Network Architecture and protocol structure
WCDMA Wireless Fundamental
Physical Layer Overview
Physical Channels
Physical Layer Procedure
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WCDMA Network Architecture
RNS
RNC
RNS
RNC
Core Network
Node B Node B Node B Node B
Iu-CS Iu-PS
Iur
Iub Iub Iub Iub
CN
UTRAN
UE Uu
CS PS Iu-CS Iu-PS
CS PS
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WCDMA Network 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
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WCDMA Network Version Evolution
Features of R6
MBMS is introduced
HSUPA is introduced to achieve the service rate up to 5.76Mbps
Features of R7
HSPA+ is introduced, which adopts higher order modulation and MIMO
Max DL rate: 28Mbps, Max UL rate:11Mbps
Features of R8
WCDMA LTE (Long term evolution) is introduced
OFDMA is adopted instead of CDMA
Max DL rate: 50Mbps, Max UL rate: 100Mbps (with 20MHz bandwidth)
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Contents
3G Overview
CDMA Principle
WCDMA Network Architecture and protocol structure
WCDMA Wireless Fundamental
Physical Layer Overview
Physical Channels
Physical Layer Procedure
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Processing Procedure of WCDMA System
Source Coding
Channel Coding & Interleaving Spreading Modulation
Source Decoding
Channel Decoding & Deinterleaving Despreading Demodulation
Transmission
Reception
chip modulated signal bit symbol
Service Signal
Radio Channel
Service Signal
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_12.20 12.2 (GSM EFR)
AMR_10.20 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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Processing Procedure of WCDMA System
Transmitter
Source Coding
Channel Coding & Interleaving Spreading Modulation
Source Decoding
Channel Decoding & Deinterleaving Despreading Demodulation
Transmission
Reception
chip modulated signal bit symbol
Service Signal
Radio Channel
Service Signal
Receiver
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WCDMA Block Coding - CRC
Block coding is used to detect if there are any uncorrected errors left after error correction.
The cyclic redundancy check (CRC) is a common method of block coding.
Adding the CRC bits is done before the channel encoding and they are checked after the channel decoding.
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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
11101........................0000100
0 0 1 0 0 0 0 . . . 1 0 1 1 1
11101........................0000010 0 0 … 0 1 0 … 1 0 0 … 1 0 … 1 1
Inter-column permutation
Output bits
Input bits
Interleaving periods: 20, 40, or 80 ms
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Processing Procedure of WCDMA System
Source Coding
Channel Coding & Interleaving Spreading Modulation
Source Decoding
Channel Decoding & Deinterleaving Despreading Demodulation
Transmission
Reception
chip modulated signal bit symbol
Service Signal
Radio Channel
Service Signal
Receiver
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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
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 and others
Processing Gain
Ebit
Interference from other UE Echip
Eb / No = Ec / No ×PG
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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 bitrate chiplog(10Gain ocessPr =
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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
scrambling channelization
Data symbol
Chips after spreading
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WCDMA Channelization Code
OVSF Code (Orthogonal Variable Spreading Factor) is used as channelization code
SF = 8 SF = 1 SF = 2 SF = 4
C ch,1,0 = (1)
C ch,2,0 = (1,1)
C ch,2,1 = (1, -1)
C ch,4,0 = (1,1,1,1)
C ch,4,1 = (1,1,-1,-1)
C ch,4,2 = (1,-1,1,-1)
C ch,4,3 = (1,-1,-1,1)
C ch,8,0 = (1,1,1,1,1,1,1,1)
C ch,8,1 = (1,1,1,1,-1,-1,-1,-1)
C ch,8,2 = (1,1,-1,-1,1,1,-1,-1)
C ch,8,3 = (1,1,-1,-1,-1,-1,1,1)
C ch,8,4 = (1,-1,1,-1,1,-1,1,-1)
C ch,8,5 = (1,-1,1,-1,-1,1,-1,1)
C ch,8,6 = (1,-1,-1,1,1,-1,-1,1)
C ch,8,7 = (1,-1,-1,1,-1,1,1,-1)
……
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WCDMA Channelization Code
SF = chip rate / symbol rate
High data rates → low SF code
Low data rates → high SF code
Radio bearer SF Radio bearer SF
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
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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 in one carrier
For uplink, scrambling code is used to separate different UEs in one carrier
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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 signals. Uplink scrambling codes are assigned by RNC.
For downlink, 512 primary scrambling codes are used.
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Primary Scrambling Code Group
Primary scrambling codes for downlink physical channels
Group 0
…
Primary scrambling code 0
……
Primary scrambling code
8*63
……
Primary scrambling code
8*63 +7 512 primary scrambling
codes
……
……
Group 1
Group 63
Primary scrambling code 1
Primary scrambling code 8
64 primary scrambling code
groups Each group consists of 8
primary scrambling codes
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Code Multiplexing
Downlink Transmission on a Cell Level
Scrambling code
Channelization code 1
Channelization code 2
Channelization 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
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Processing Procedure of WCDMA System
Source Coding
Channel Coding & Interleaving Spreading Modulation
Source Decoding
Channel Decoding & Deinterleaving Despreading Demodulation
Transmission
Reception
chip modulated signal bit symbol
Service Signal
Radio Channel
Service Signal
Receiver
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Modulation Overview
1 0 0 1
time
Basic steady radio wave:
carrier = A.cos(2πFt+φ)
Amplitude Shift Keying:
A.cos(2πFt+φ)
Frequency Shift Keying:
A.cos(2πFt+φ)
Phase Shift Keying: A.cos(2πFt+φ)
Data to be transmitted: Digital Input
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Modulation Overview
Digital Modulation - BPSK
1
t
1 1 0
1
t -1
NRZ coding
fo
BPSK Modulated
BPSK signal
Carrier
Information signal
φ=0 φ=π φ=0
1 10 2 3 4 9 8 7 5 6
1 10 2 3 4 9 8 7 5 6
Digital Input
High Frequency Carrier
BPSK Waveform
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Modulation Overview
Digital Modulation - QPSK
-1 -1
1 10 2 3 4 9 8 7 5 6
1 10 2 3 4 9 8 7 5 6
NRZ Input
I di-Bit Stream
Q di-Bit Stream
I Component
Q Component
QPSK Waveform
1
1
-1
1
-1
1
1
-1
-1
-1
1 1 -1 1 -1 1 1 -1
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Modulation Overview
NRZ coding
90o
NRZ coding
QPSK
Q(t)
I(t)
fo
±A
±A ±Acos(ωot)
±Acos(ωot + π/2)
φ 1 1 π/4 1 -1 7π/4 -1 1 3π/4 -1 -1 5π/4
)cos(2: φω +oAQPSK
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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
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WCDMA Modulation
Different modulation methods corresponding to different transmitting abilities in air interface
HSDPA: QPSK or 16QAM R99/R4: QPSK
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Processing Procedure of WCDMA System
Source Coding
Channel Coding Spreading Modulation
Source Decoding
Channel Decoding Despreading Demodulation
Transmission
Reception
chip modulated signal bit symbol
Service Signal
Radio Channel
Service Signal
Transmitter
Receiver
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Wireless Propagation
Received Signal
Transmitted Signal
Transmission Loss: Path Loss + Multi-path Fading
Time
Amplitude
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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
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
Polarization diversity
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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
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Contents
3G Overview
CDMA Principle
WCDMA Network Architecture and protocol structure
WCDMA Wireless Fundamental
Physical Layer Overview
Physical Channels
Physical Layer Procedure
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UTRAN Network Structure
RNS
RNC
RNS
RNC
Core Network
NodeB NodeB NodeB NodeB
Iu-CS Iu-PS
Iur
Iub Iub Iub Iub
CN
UTRAN
UE Uu
CS PS Iu-CS Iu-PS
CS PS
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Contents
3G Overview
CDMA Principle
WCDMA Network Architecture and protocol structure
WCDMA Wireless Fundamental
Physical Layer Overview
Physical Channels
Physical Layer Procedure
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WCDMA Radio Interface Channel Definition
Logical Channel = information container
Defined by <What type of information> is transferred
Transport Channel = characteristics of transmission
Described by <How> and with <What characteristics> data is transmitted over the radio interface
Physical Channel = specification of the information global content
providing the real transmission resource, maybe a frequency , a specific set of codes and phase
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Logical Channel
Control channel
Traffic channel Dedicated traffic channel (DTCH)
Common traffic channel (CTCH)
Broadcast control channel (BCCH)
Paging control channel (PCCH)
Dedicate control channel (DCCH)
Common control channel (CCCH)
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Transport Channel
Dedicated Channel (UL,DL) (DCH)
Broadcast channel (DL) (BCH)
Forward access channel (DL) (FACH)
Paging channel (DL) (PCH)
Random access channel (UL) (RACH)
High-speed downlink shared channel(UL,DL) (HS-DSCH)
Common transport channel
Dedicated transport channel
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Physical Channel
A physical channel is defined by a specific carrier frequency, code (scrambling code, spreading code) and relative phase.
In UMTS system, the different code (scrambling code or spreading code) can distinguish the channels.
Most channels consist of radio frames and time slots, and each radio frame consists of 15 time slots.
Two types of physical channel: UL and DL
Physical Channel
Frequency, Code, Phase
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Downlink Physical Channel
Downlink Dedicated Physical Channel (DL DPCH)
Downlink Common Physical Channel
Primary Common Control Physical Channel (P-CCPCH)
Secondary Common Control Physical Channel (S-CCPCH)
Synchronization Channel (SCH)
Paging Indicator Channel (PICH)
Acquisition Indicator Channel (AICH)
Common Pilot Channel (CPICH)
High-Speed Physical Downlink Shared Channel (HS-PDSCH)
High-Speed Shared Control Channel (HS-SCCH)
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Uplink Physical Channel
Uplink Dedicated Physical Channel
Uplink Dedicated Physical Data Channel (Uplink DPDCH)
Uplink Dedicated Physical Control Channel (Uplink DPCCH)
High-Speed Dedicated Physical Channel (HS-DPCCH)
Uplink Common Physical Channel
Physical Random Access Channel (PRACH)
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Function of Physical Channel
NodeB
UE
P-CCPCH-Primary Common Control Physical Channel
P-CPICH--Primary Common Pilot Channel SCH--Synchronisation Channel
Cell Search Channels
DPDCH--Dedicated Physical Data Channel
DPCCH--Dedicated Physical Control Channel
Dedicated Channels
Paging Channels PICH--Paging Indicator Channel
SCCPCH--Secondary Common Control Physical Channel
PRACH--Physical Random Access Channel
AICH--Acquisition Indicator Channel Random Access Channels
HS-DPCCH--High Speed Dedicated Physical Control Channel
HS-SCCH--High Speed Share Control Channel
HS-PDSCH--High Speed Physical Downlink Share Channel
High Speed Downlink Share Channels
Thank You
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