WCDMA Physical Layer Design

1
WCDMA Physical Layer Design

• A. Chockalingam
• Assistant Professor
• Indian Institute of Science, Bangalore-12
• achockal_at_ece.iisc.ernet.in
• http//ece.iisc.ernet.in/achockal

2
Outline

• WCDMA Network Architecture
• WCDMA Physical Layer
• Physical / Transport / Logical Channels
• Uplink
• Spreading - Channelisation / Scrambling
• Transport Formats and Configuration
• Multiplexing and Channel Coding
• Downlink
• Spreading / Scrambling / Channelisation
• Multiplexing and Channel Coding

3
2G to 3G Evolution
EDGE
D A T A
GSM
GPRS
WCDMA
IMT2000
I S 9 9
IS-95A
IS-95B
cdma2000
IMT2000 ITUs Standardization Effort towards
3G (IMT-2000 previously termed
as FPLMTS) UMTS European Effort (Specified by 3G
Partnership Project 3GPP)
4
UMTS NW Model
Non-access Stratum (Protocols between UE and Core
NW)
Access Stratum (Protocols between UE and Access
NW)
Home Network
Zu
Serving Network PS/CS
Transit Network
Access Network
Mobile Equipment
USIM
Cu
Uu
Iu
Yu
User Equipment
Access Network
Core Network
Infrastructure
Stratum Refers to a way of
grouping protocols handling activities
5
UMTS NW Architecture
Uu
Iu
UTRAN
CN
RNS
CN (CS Domain)
Iub
Node B
3G MSC / VLR
3G GMSC
RNC
UE
Node B
Registers
Iur
HLR/AuC/EIR (Home Network)
UE
RNS
Node B
CN (PS Domain)
RNC
SGSN
GGSN
Node B
UE
6
WCDMA System Features

• UTRA FDD mode and TDD mode
• UTRA FDD features
• Multiple Access CDMA
• Channel Spacing 5 MHz
• Chip Rate 3.84 Mcps
• Frame Length 10 msec
• Time Slots 15 slots per 10 msec frame
• Spreading Factor 4 to 512
• Multi-rate Through Multi-code or
• Orthogonal
  Variable Spreading

7
UTRA FDD Features

• FEC Codes Rate 1/2, 1/3 convolutional code
• with
  constraint length K 9
• Rate 1/3, 8-state Turbo coding
• Interleaving Intra- or Inter-frame interleaving
  
• (10, 20 40,
  80 msec)
• Modulation QPSK
• Detection Coherent based on pilot symbols
• Micro diversity RAKE in BS and UE
• Power Control Fast closed-loop at 1500 Hz rate
• Intra-frequency HO Soft / Softer Handover
• Inter-frequency HO Hard Handover
• Interference Cancellation Support for multiuser
  detection

8
Radio Interface Protocol Model
USER PLANE
CONTROL PLANE
L3 (Radio Network Layer)
RRC
U-Plane Radio Bearers
User Plane Radio Bearers
Signalling Radio Bearers
Control
PDCP
BMC
L2 (Radio Link Layer)
RLC
Logical Channels
MAC
Transport Channels
L1 (Radio Physical Layer)
PHY
9
WCDMA Radio Channels

• Physical Channels
• Transmission media.
• Two types of physical channels defined in L1 FDD
  and TDD.
• FDD is characterized by frequency, code, I/Q
  phase
• Follow a layered structure of radio frames and
  time slots
• Transport Channels
• describes the way information is transferred over
  the radio interface
• Logical Channels
• the type of information transferred characterizes
  a logical channel

UE
BS
RNC
Logical Channels
Transport Channels
Physical Channels
10
Physical Channels

• Corresponds to a specific carrier frequency,
  code, relative phase in I and Q branches
• Dedicated and Common Physical Channels
• Layered structure of radio frames and time slots
• A radio frame 10 msec 15 slots/frame
• 1 frame 38400 chips, 1 slot 2560 chips
• Slot configuration varies depending on the
  channel bit rate of the physical channel
• bits/slot different for different physical
  channels
• may vary with time (on a frame by frame basis)

11
U/L Physical Channels

• Dedicated U/L Channels
• DPDCH
• DPCCH
• Common U/L Channels
• PRACH
• Preamble part
• Message part
• PCPCH
• Preamble part
• Message part

12
Dedicated U/L Physical Channels

• Two types
• Dedicated Physical Data CHannel (DPDCH)
• Dedicated Physical Control CHannel (DPCCH)
• Both are I/Q code multiplexed within each radio
  frame
• U/L DPDCH carries the DCH transport channel
• U/L DPCCH carries L1 control bits such as
• Pilot bits (to enable channel estimation for
  coherent detection at BS)
• Transmit power control (TPC) commands
• Feedback Information (FBI)
• used for CL transmit diversity and Site Selection
  Diversity Transmission (SDTC)
• Transport Format Combination Indicator (TFCI)
• for several simultaneous services. Informs the rx
  of the transport format combination of the
  transport channels mapped to DPDCH

13
U/L Frame Structure

• There is only one U/L DPCCH on each radio link
• There can be 0, 1, or several DPDCHs on each
  radio link
• 10 msec frames divided into 15 slots

1 Frame 15 slots 10 msec
S0
S1
S2
S3
S13
S14
1 time slot 2/3 msec
DPDCH (on I-Chl)
(Ndata bits)
DATA
DPCCH (on Q-Chl)
Pilot
TFCI
FBI
TPC
10 bits 2560 chips gt SF 256
14
I, Q Spreading for DPDCH, DPCCH
Cc, Cd,n Channelization codes Sdpch,n
Scrambling code Bd, Bc Gain factors
DPDCH-1
Cd,1
Bd
I
DPDCH-3
Cd,3
Bd
IjQ
DPDCH-2
Sdpch,n
Q
Cd,2
Bd
j
DPCCH-2
Cc
Bc
Up to 6 DPDCHs in parallel
15
WCDMA Transmission Rates (U/L)

• System Chip Rate 3.84 Mcps
• Symbol Rates on Uplink
• Chl Symb Rate Chl Bit Rate SF
  Bits/frame Ndata
• 15 Ks/s 15 Kb/s 256 150
  10
• 30 Ks/s 30 Kb/s 128 300
  20
• 60 Ks/s 60 Kb/s 64
  600 40
• 120 Ks/s 120 Kb/s 32
  1200 80
• 240 Ks/s 240 Kb/s 16
  2400 160
• 480 Ks/s 480 Kb/s
  8 4800 320
• 960 Ks/s 960 Kb/s
  4 9600 640

16
WCDMA Channelisation Codes

• Orthogonal codes
• Used for channel separation both in U/L and D/L
  directions
• Can have different spreading factor values (thus
  support different symbol rates)
• Cch,SF,k SF - Spreading Factor, k is the code
  number 0ltklt SF-1
• Spreading factor value indicates how many bits of
  those codes are used in a connection

17
U/L Channelization Codes

• Orthogonal Variable Spreading Factor (OVSF)
• channelization codes
• Separates data / control channels from same UE
• Preserves orthogonality between these channels

SF4
SF2
(1,1,1,1)
SF1
(1,1)
(1,1,-1,-1)
(1)
C(SF,k)
(1,-1,1,-1)
(1,-1)
SF Spreading Factor k code number 0ltkltSF-1
(1,-1,-1,1)
18
U/L Scrambling Codes

• Use complex valued scrambling code
• Long scrambling sequences (224)
• Gold sequences (linear combination of two
  m-sequences)
• Short scrambling sequences (224)
• from a family sequence of periodically extended
  S(2) codes
• Long or short sequences for DPCCH / DPDCH
• Only long sequences for message parts of PRACH
  and PCPCH

19
WCDMA Code Types

• Scrambling Codes, Channelisation Codes
• Uplink Downlink
• Scrambling codes User separation Cell separation
• Channelisation Data and Control Users within a
• codes channels from the cell
• same terminal
• Spreading code Scrambling code x
  Channelisation code

20
Common U/L Physical Channels

• Two Types
• Physical Random Access CHannel (PRACH)
• Physical Common Packet CHannel (PCPCH)
• Physical Random Access CHannel (PRACH)
• carries RACH
• Uses S-ALOHA technique with fast Acquisition
  Indication
• Access slots (15 access slots per 2 frames)
• RA transmission consists of
• several 4096 chip preambles (uses 256 repetitions
  of 16 chips signature sequence) and 1or 2 frame
  message

Message Part (1 or 2 frames)
Preamble
Preamble
4096 Chips
21
Random Access
UE
BS
PRACH Preamble sent (initial access)
No detection on AICH
PRACH Preamble sent (initial access)
AICH Preamble sent detected
PRACH Random Access Info sent
22
Common U/L Physical Channels

• Physical Common Packet CHannel (PCPCH)
• Carries CPCH
• CPCH is based on DSMA-CD technique with fast
  Acquisition Indication
• Access slot timing and structure are identical to
  those defined for RACH
• Transmission consists of
• Access preamble(s) - one or several each 4096
  chips
• Collision Detection preamble
• DPCCH Power Control Preamble (0 or 8 slots)
• Message of variable length (Nx10 msec)
• PCPCH good for carrying small sized bursty data

23
Transport Formats / Configurations

• Transport Block (TB)
• Basic unit of data exchanged between L1 MAC for
  L1 processing
• Transport Block Size Number of bits in a TB.
• Transport Block Set (TBS)
• A set of TBs exchanged between L1 and MAC at the
  same time instant using the same transport
  channel
• Transport Block Set Size Number of bits in a TBS
• Transmission Time Interval (TTI)
• Periodicity at which a TBS is transferred by the
  physical layer on to the radio interface - 10,
  20, 40, 80 ms
• MAC delivers one TBS to the physical layer every
  TTI

24
Transport Formats / Configurations

• Transport Format (TF)
• Format offered by L1 to MAC (and vice versa) for
  the delivery of a
• TBS during a TTI on a given transport channel
  (TrCH)
• Dynamic part (TB size, TBS size)
• Semi-static part (TTI, type/rate of coding,size
  of CRC)
• TB size, TBS size, TTI define the TrCH bit rate
  before L1 processing
• e.g., TB size 336 bits (320 bit payload 16
  bits RLC header)
• TBS size 2 TBs per TTI, TTI 10 ms
• DCH Bit rate (with RLC header)
  3362/10 67.2 Kbps
• User Bit rate (without RLC header)
  3202/10 64 Kbps
• Variable bit rate can be achieved by changing
  (between TTIs)
• either the TBS size only, or both the TB size
  and TBS Size
• Transport Format Set (TFS)
• a set of TFs associated with a TrCH
• semi-static part of all TFs in a TFS is the same

25
Transport Formats / Configurations

• Transport Format Combination (TFC)
• Multiple TrCHs each having a TF
• Authorized combination of the currently valid TFs
  that can be submitted to L1 on a CCTrCH,
  containing one TF from each TrCH
• Transport Format Combination Set (TFCS)
• A set of TFCs on a CCTrCH. Produced by RNC
• TFCS is given to MAC by L3 for control
• MAC chooses between the different TFCs specified
  in the TFCS
• MAC has control over only the dynamic part of
  the TFs. Semi-static part relates to QoS (e.g.,
  quality) and is controlled by RNC admission
  control
• Bit rate can be changed quickly by MAC with no
  need to L3 signaling
• Transport Format Indicator (TFI)
• A label for a specific TF within a TFS. Used
  between MAC and L1
• Transport Format Combination Indicator (TFCI)
• Used to inform the receiving side of the
  currently valid TFC

26
Transport Formats / Configurations
Transport Format Combination (TFC)
DCH1
TB
TB
TB
TTI
TTI
TTI
Transport Block Set (TBS)
TB
TB
TB
DCH2
TB
TB
TB
TTI
TTI
TTI
Transport Format Combination Set (TFCS)
Transport Format Set (TFS)
Transport Format (TF)
27
TFI and TFCI (Transmitter)
E.g Two transport channels mapped to a single
physical channel
Transport Chl 1
Transport Chl 2
Transport Block
Transport Block
Transport Block
Transport Block
Higher Layer
TFI
TFI
This dotted line represents the Iur interface in
case of NW side
Physical Layer
Coding and Multiplexing
TFCI
Physical Control Chl
Physical Data Chl
DPCCH (Q-Chl)
DPDCH (I-Chl)
28
TFI and TFCI (Receiver)
Transport Chl 2
Transport Chl 1
Transport Block EI
Transport Block EI
EI Error Indication
Transport Block EI
Transport Block EI
Higher Layer
TFI
TFI
Physical Layer
Decoding and Demultiplexing
TFCI Decode
Physical Control Chl
Physical Data Chl
DPDCH (I-Chl)
DPCCH (Q-Chl)
29
TFI and TFCI

• Each transport channel is accompanied by a TFI at
  each time event at which data is expected to
  arrive from HL
• Physical layer combines the TFI info from
  different
• transport channels to the TFCI
• TFCI is sent on the DPCCH to inform the receiver
  about
• the instantaneous transport format
  combination of the
• transport channels mapped to the U/L DPDCH
• transmitted simultaneously

30
Transport Format (e.g., Speech)

• Conversational Speech (12 Kbps)
• 12.2 Kbps max.
• TTI 20 msec
• Transport Formats (TF) available
• TF RAB1 RAB2
  RAB3
• TF0v 0 x 81 0 x 103
  0 x 60 (e.g., silence)
• TF1v 1 x 81 1 x 103
  1 x 60 (e.g, active voice)
• two other formats too (see Stds. Doc.)
• TFC (TF0, TF0, TF0) e.g., during silence
• (TF1, TF1, TF1) e.g., during
  active voice periods

31
Transport Format (e.g., Data)

• Interactive/Background Data (64 Kbps)
• 64 Kbps max.
• TTI 20 msec
• Transport Block (TB) size 336 bits
• Transport Formats (TF) available
• TF0 - 0 x 336
• TF1 - 1 x 336
• TF2 - 2 x 336
• TF3 - 3 x 336
• TF4 - 4 x 336

32
Transport Format (Speech Data)

• Conversational speech (12 Kbps)
  Interactive/Background Data (64 Kbps)
• Voice TrCH
  Data TrCH
• TFC1 (TF0v, TF0v, TF0v)
  TF0d
• TFC2 (TF0v, TF0v, TF0v)
  TF1d
• TFC3 (TF0v, TF0v, TF0v)
  TF2d
• TFC4 (TF0v, TF0v, TF0v)
  TF3d
• TFC5 (TF0v, TF0v, TF0v)
  TF4d
• TFC6 (TF1v, TF1v, TF1v)
  TF0d
• TFC7 (TF1v, TF1v, TF1v)
  TF1d
• TFC8 (TF1v, TF1v, TF1v)
  TF2d
• TFC9 (TF1v, TF1v, TF1v)
  TF3d
• TFC10 (TF1v, TF1v, TF1v)
  TF4d

33
Multiplexing Channel Coding

• Data arrives at the coding/mux unit in transport
  block sets, once every transmission time interval
  (TTI)
• TTI depends on the transport channel 10, 20,
  40, 80 ms)
• Main steps
• Add CRC to each block
• transport block concatenation and block
  segmentation
• channel coding
• first interleaving (per TTI)
• radio frame segmentation (when TTI gt 10 ms)
• rate matching (repetition or puncturing)
• multiplexing of transport channels (CCTrCH)
• insertion of DTX indication bits
• physical channel segmentation
• second interleaving (per radio frame, ie., among
  bits in 1 radio frame)
• mapping to physical channel

34
Multiplexing Channel Coding (U/L)
CRC Attachment
CRC Attachment
TrCH-1
TrBk Concatenation/ Code Block Segmentation
TrBk Concatenation/ Code Block Segmentation
TrCH-2
Channel Coding
Channel Coding
Radio Frame Equalization
Radio Frame Equalization
1st Interleaving
1st Interleaving
Radio Frame Segmentation
Radio Frame Segmentation
Rate Matching
Rate Matching
TrCH Multiplexing
CCTrCH
Physical Channel Segmentation
2nd interleaving
Physical Channel Mapping
PhCH2
PhCH1
35
Multiplexing Channel Coding (..cntd)

• Applicable to DCH, RACH, CPCH, DSCH, BCH, FACH,
  PCH
• CRC
• add CRC to each transport block for error
  detection
• CRC calculated on entire transport block
• Size of CRC 24, 16, 12, 8, 0 bits
• what CRC size is used for each TrCH is signaled
  from higher layers

36
Multiplexing Channel Coding (..cntd)

• TrBk Concatenation Code Block Segmentation
• all transport blocks in a TTI are concatenated
• if no. of bits in a TTI after concatenation (X)
  is greater than the maximum size of the code
  block (in the channel coding block), then code
  block segmentation is done
• max. size of the code block (Z) depends on
  whether
• Convolutional code ( Z 504 bits) or
• Turbo code ( Z 5114 bits) is used for the TrCH
• Code blocks after segmentation are of the same
  size
• Filler bits (zeros) added to 1st coded block to
• to make integer number of code blocks, or
• if X lt 40 bits when Turbo code is used

37
Multiplexing Channel Coding (..cntd)

• Channel Coding

Type of TrCH
Coding Scheme
Coding Rate
BCH
Convolutional Coding (constraint length 9)
PCH
1/2
RACH
1/3, 1/2
DPCH, DCH, DSCH, FACH
Turbo Coding
1/3
If number of coded blocks is greater than 1, they
are serially concatenated
38
Multiplexing Channel Coding (..cntd)

• Radio Frame Equalization
• padding the input bit sequence in order to ensure
  that the output can be segmented into data
  segments of equal size
• I.e., number of bits per segment is same after
  radio frame equalization
• performed only on the U/L
• 1st Interleaving
• block interleaver
• among bits in a TTI

39
Multiplexing Channel Coding (..cntd)

• Radio Frame Segmentation
• when TTI gt 10 msec, input bit sequence is
  segmented and mapped on to Fi consecutive radio
  frames
• Rate Matching
• means that bits on a transport channel are
  repeated or punctured to ensure that the total
  bit rate after TrCH multiplexing is identical to
  the total channel bit rate of the allocated
  dedicated physical channels
• higher layers assign a rate-matching
  (semi-static) attribute for each transport
  channel
• this attribute is used to calculate the number of
  bits to repeat or puncture, spreading factor,
  number of PhCHs needed, rate matching pattern

40
Multiplexing Channel Coding (..cntd)

• TrCH Multiplexing
• every 10 msec, one radio frame from each TrCH is
  delivered to the TrCH multiplexing
• these radio frames are serially concatenated into
  a coded composite transport channel (CCTrCH)
• Physical Channel Segmentation
• when more than once PhCH is used, the physical
  channel segmentation divides the bits among
  different PhCHs
• 2nd Interleaving
• among bits within a radio frame

41
Multiplexing Channel Coding (..cntd)

• Insertion of Discontinuous Transmission (DTX)
  Indication Bits
• only on the D/L
• used to fill up the radio frame with bits
• insertion point depends on whether fixed
  positions (1st Insertion) or flexible positions
  (2nd Insertion) of the TrCHs in the radio frame
  are used
• During connection setup, NW decides if fixed or
  flexible position is used for each CCTrCH
• DTX Indication bits are not transmitted they
  only tell when the Tx must be turned off

42
Multiplexing Channel Coding (..cntd)

• Transport Format Detection
• TFCI Based Detection
• Explicit Blind Detection
• using receive power ratio
• by use of channel decoding and CRC check
• Guided Detection
• Explicit blind detection used on Guiding TrCH
• Guiding TrCH has the same TTI as the TrCH under
  consideration

43
Multiplexing Channel Coding (..cntd)

• Blind Transport Format Detection
• Using Received Power Ratio (for the case of 2
  TFs)
• Ratio of the power received on DPDCH (Pd) and
  DPCCH (Pc)
• Full Rate TF if ratio Pd/Pc gt threshold
• Zero rate TF if ratio Pd/Pc lt threshold
• Using CRC (for the case of multiple TFs)
• Receiver knows only the possible TFs or end bit
  (thru L3 signaling)
• Receiver performs FEC (Viterbi) decoding
• path metric selection among the surviving paths
  in the decoding

44
D/L Physical Channels

• Dedicated D/L Channels
• DPDCH
• DPCCH
• Common D/L Channels
• Common PIlot CHannel (CPICH)
• Primary CPICH
• Secondary CPICH
• Common Control Physical CHannel (CCPCH)
• Primary CCPCH,
• Secondary CCPCH
• Synchronization CHannel (SCH)
• Primary SCH,
• Secondary SCH

45
Dedicated D/L Physical Channels

• Dedicated Physical CHannel (D/L DPCH)
• transmits dedicated data generated at L2 and
  above
• time-multiplexes with L1 control bits (Pilot,
  TPC, TFCI)
• D/L DPCH
• Time-multiplex of a D/L DPDCH and a D/L DPCCH

46
DL Frame Structure

• 10 msec frames divided into 15 slots
• No. of bits in different DPDCH field (Npilot,
  Ntpc, Ntfci, Ndata1, Ndata2) are given in tables
• Which slot format to use is configured (and
  reconfigured) by higher layers

1 Frame 15 slots 10 msec
S0
S1
S2
S3
S13
S14
1 time slot 2/3 msec
Pilot
TFCI
TPC
DATA 1
DATA 2
DPCCH
DPDCH
DPCCH
DPDCH
47
D/L Transmission

• Multicode Transmission on D/L
• Multicode transmission can be employed on the D/L
• I.e., CCTrCH is mapped on to several parallel D/L
  DPCHs using the same spreading factor
• In this case, L1 control information is sent only
  on the first downlink DPCH
• Multiple CCTrCHs
• In case there are several CCTrCHs mapped to
  different DPCHs transmitted to the same UE,
  different spreading factors can be used on DPCHs
• multiple CCTrCHs feature for future release

48
WCDMA Transmission Rates (D/L)

• System Chip Rate 3.84 Mcps
• Symbol Rates on Downlink
• Symb Rate Chl bit rate SF
• 7.5 Ks/s 15 Kb/s 512
• 15 Ks/s 30 Kb/s 256
• 30 Ks/s 60 Kb/s 128
• 60 Ks/s 120 Kb/s
  64
• 120 Ks/s 240 Kb/s
  32
• 240 Ks/s 480 Kb/s 16
  
• 480 Ks/s 960 Kb/s
  8
• 960 Ks/s 1920 Kb/s 4
  

49
Common D/L Physical Channels

• Common Pilot CHannel (CPICH)
• 30 Kbps fixed rate channel (SF 256)
• Primary CPICH
• Always uses the same channelization code
• Scrambled by primary scrambling code
• There is one and only one P-CPICH per cell
• Broadcast over the entire cell
• Provides a phase reference for several D/L
  channels
• Secondary CPICH
• Uses an arbitrary channelization code of SF256
• Scrambled either by the primary or a secondary
  scrambling code
• A cell may contain 0,1, or several S-CPICH
• Broadcast over entire OR part of a cell
• A S-CPICH can be a phase reference to some D/L
  channels (which is communicated to the UE thru
  higher layer signaling)

50
Common D/L Physical Channels

• Common Control Physical CHannel (CCPCH)
• Primary CCPCH (P-CCPCH)
• 30 Kbps fixed rate channel with SF256
• Carries BCH transport channel
• No TPC, TFCI, pilot bits are sent
• the transport channel mapped to P-CCPCH (I.e.,
  BCH) can only have a fixed predefined TFC
• Secondary CCPCH (S-CCPCH)
• Carries FACH and PCH
• S-CCPCH can be with TFCI and without TFCI
• NW decides if TFCI has to be sent
• So UE should be (mandatory) capable of receiving
  with or without TFCI (i.e., blind)
• S-CCPCH can support multiple TFCs using TFCI
• Main difference between CCPCHs and Dedicated
  Physical Channels a CCPCH is NOT inner loop
  Power Controlled

51
Common D/L Physical Channels

• Synchronization CHannel (SCH)
• Downlink signal used for cell search
• Consists of Primary and Secondary subchannels
• Primary SCH
• Uses Primary Sychronization Code (PSC), TX once
  every slot
• PSC is the same for every cell in the system
• Secondary SCH
• Tx in parallel with Primary SCH
• SSC indicates which of the code groups (64
  groups) the cells DL scrambling code belongs to

52
D/L Spreading
I
DL Physical Channel data
Serial to Parallel Conv.
IjQ
Cd,SF,m
Sdl,n
Q
j
Channelisation code - Differentiate users in a
cell - OVSF
- UTRAN assigns
channelisation codes to diff. phy.
chls Scrambling Code Differentiate cells
53
Scrambling Codes

• possible D/L scrambling codes 218 -1
  262143
• Scrambling codes divided into 512 sets
• 1 primary scrambling code and 15 secondary
  scrambling codes
• So, there are 512 x 16 8192 codes
• Each cell is allocated one and only primary
  scrambling code
• The primary CCPCH (Common Control Physical
  CHannel) is Tx always using this primary
  scrambling code
• Other D/L physical channels can be Tx with either
  the PSC or SSC from the set associated with the
  PSC of the cell

54
Multiplexing Channel Coding (D/L)
CRC Attachment
CRC Attachment
TrCH-1
TrBk Concatenation/ Code Block Segmentation
TrBk Concatenation/ Code Block Segmentation
TrCH-2
Channel Coding
Channel Coding
Rate Matching
Rate Matching
1st Insertion of DTX Indication
1st Insertion of DTX Indication
1st Interleaving
1st Interleaving
Radio Frame Segmentation
Radio Frame Segmentation
TrCH Multiplexing
CCTrCH
2nd Insertion of DTX Indication
Physical Channel Segmentation
2nd interleaving
Physical Channel Mapping
PhCH2
PhCH1
55
Multiplexing Channel Coding (..cntd)

• Physical Channel Mapping
• on U/L PhCHs are either completely filled or not
  
• used at all
• on D/L No bits in locations with DTX indication
• in compressed mode, no bits are mapped to certain
  slots in a PhCH. Reducing the SF by a factor of
  2, 7.5 slots per frame is used in compressed mode

56
Multiplexing Channel Coding (..cntd)

• Insertion of Discontinuous Transmission (DTX)
  Indication Bits
• only on the D/L
• used to fill up the radio frame with bits
• insertion point depends on whether fixed
  positions (1st Insertion) or flexible positions
  (2nd Insertion) of the TrCHs in the radio frame
  are used
• During connection setup, NW decides if fixed or
  flexible position is used for each CCTrCH
• DTX Indication bits are not transmitted they
  only tell when the Tx must be turned off

57
WCDMA Physical Channels
P-CCPCH
S-CCPCH
DPDCH
DPCCH
PDSCH
PCPCH
PRACH
BS
UE
AICH
P-SCH
S-SCH
CSICH
CPICH
PICH
CD/CA-ICH
58
Channel Mapping on the U/L
Logical Channels
CCCH
DTCH
DCCH
Transport Channels
RACH
DCH
CPCH
Physical Channels
PRACH
DPDCH
DPCCH
PCPCH
59
Channel Mapping on the D/L
Logical Channels
BCCH
PCCH
CTCH
CCCH
DCCH
DTCH
Transport Channels
BCH
PCH
FACH
DCH
DSCH
Physical Channels
P-CCPCH
S-CCPCH
DPDCH
DPCCH
PDSCH