WCDMA Physical Layer Design

WCDMA Physical Layer Design
A. Chockalingam Assistant Professor Indian Institute of Science, Bangalore-12

Dept of ECE, IISc, Bangalore
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 Dr. A. Chockalingam Dept of ECE, IISc, Bangalore

2G to 3G Evolution EDGE D A T GSM GPRS WCDMA IMT2000 I S 9 IS-95A IS-95B cdma2000 IMT2000: ITU’s Standardization Effort towards 3G (IMT-2000 previously termed as FPLMTS) UMTS: European Effort (Specified by 3G Partnership Project 3GPP) Dr. A. Chockalingam Dept of ECE, IISc, Bangalore

UMTS NW Model Non-access Stratum Access Stratum Home Network Zu
(Protocols between UE and Core NW) Access Stratum (Protocols between UE and Access NW) Home Network Zu Serving Network PS/CS Access Network Transit Network Mobile Equipment USIM Cu Uu Iu Yu User Equipment Access Network Core Network Stratum: Refers to a way of grouping protocols handling activities Infrastructure Dr. A. Chockalingam Dept of ECE, IISc, Bangalore

UMTS NW Architecture Uu Iu UTRAN CN RNS Iub CN (CS Domain) Node B RNC 3G MSC / VLR 3G GMSC UE Node B Registers Iur HLR/AuC/EIR (Home Network) UE RNS Node B CN (PS Domain) RNC SGSN GGSN Node B UE Dr. A. Chockalingam Dept of ECE, IISc, Bangalore

WCDMA System Features UTRA FDD mode and TDD mode UTRA FDD features Multiple Access: CDMA Channel Spacing: 5 MHz Chip Rate: 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 Dr. A. Chockalingam Dept of ECE, IISc, Bangalore

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 Dr. A. Chockalingam Dept of ECE, IISc, Bangalore

Radio Interface Protocol Model
CONTROL PLANE USER 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 Dr. A. Chockalingam Dept of ECE, IISc, Bangalore

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 Dr. A. Chockalingam Dept of ECE, IISc, Bangalore

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 = 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) Dr. A. Chockalingam Dept of ECE, IISc, Bangalore

U/L Physical Channels Dedicated U/L Channels DPDCH DPCCH Common U/L Channels PRACH Preamble part Message part PCPCH Dr. A. Chockalingam Dept of ECE, IISc, Bangalore

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 Dr. A. Chockalingam Dept of ECE, IISc, Bangalore

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) DATA (Ndata bits) DPCCH (on Q-Chl) Pilot TFCI FBI TPC 10 bits = 2560 chips => SF = 256 Dr. A. Chockalingam Dept of ECE, IISc, Bangalore

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 I+jQ DPDCH-2 Sdpch,n Q Cd,2 Bd DPCCH-2 j Cc Bc Up to 6 DPDCHs in parallel Dr. A. Chockalingam Dept of ECE, IISc, Bangalore

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 Kb/s 30 Ks/s Kb/s 60 Ks/s Kb/s 120 Ks/s Kb/s 240 Ks/s Kb/s 480 Ks/s Kb/s 960 Ks/s Kb/s Dr. A. Chockalingam Dept of ECE, IISc, Bangalore

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 0<=k<= SF-1 Spreading factor value indicates how many bits of those codes are used in a connection Dr. A. Chockalingam Dept of ECE, IISc, Bangalore

U/L Channelization Codes Orthogonal Variable Spreading Factor (OVSF) channelization codes Separates data / control channels from same UE Preserves orthogonality between these channels SF=4 SF=2 (1,1,1,1) SF=1 (1,1) (1,1,-1,-1) C(SF,k) (1) (1,-1,1,-1) (1,-1) SF: Spreading Factor k: code number 0<k<=SF-1 (1,-1,-1,1) Dr. A. Chockalingam Dept of ECE, IISc, Bangalore

U/L Scrambling Codes Use complex valued scrambling code Long scrambling sequences (2^24) Gold sequences (linear combination of two m-sequences) Short scrambling sequences (2^24) 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 Dr. A. Chockalingam Dept of ECE, IISc, Bangalore

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 Dr. A. Chockalingam Dept of ECE, IISc, Bangalore

Common U/L Physical Channels
Two Types Physical Random Access CHannel (PRACH) Physical Common Packet CHannel (PCPCH) 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 Preamble Preamble Message Part (1 or 2 frames) 4096 Chips Dr. A. Chockalingam Dept of ECE, IISc, Bangalore

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 Dr. A. Chockalingam Dept of ECE, IISc, Bangalore

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 Dr. A. Chockalingam Dept of ECE, IISc, Bangalore

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 Dr. A. Chockalingam Dept of ECE, IISc, Bangalore

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) = 336*2/10 = 67.2 Kbps User Bit rate (without RLC header) = 320*2/10 = 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 Dr. A. Chockalingam Dept of ECE, IISc, Bangalore

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 Dr. A. Chockalingam Dept of ECE, IISc, Bangalore

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) Dr. A. Chockalingam Dept of ECE, IISc, Bangalore

E.g: Two transport channels mapped to a single physical channel
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) Dr. A. Chockalingam Dept of ECE, IISc, Bangalore

TFI and TFCI (Receiver) Transport Chl 1 Transport Chl 2 Transport Block & EI Transport Block & EI Transport Block & EI Transport Block & EI EI: Error Indication Higher Layer TFI TFI Physical Layer Decoding and Demultiplexing TFCI Decode Physical Control Chl Physical Data Chl DPCCH (Q-Chl) DPDCH (I-Chl) Dr. A. Chockalingam Dept of ECE, IISc, Bangalore

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 Dr. A. Chockalingam Dept of ECE, IISc, Bangalore

Transport Format (e.g., Speech) Conversational Speech (12 Kbps) 12.2 Kbps max. TTI: 20 msec Transport Formats (TF) available: TF RAB RAB RAB3 TF0v x x x (e.g., silence) TF1v x x x (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 Dr. A. Chockalingam Dept of ECE, IISc, Bangalore

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: TF x 336 TF x 336 TF x 336 TF x 336 TF x 336 Dr. A. Chockalingam Dept of ECE, IISc, Bangalore

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 Dr. A. Chockalingam Dept of ECE, IISc, Bangalore

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 > 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 Dr. A. Chockalingam Dept of ECE, IISc, Bangalore

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 Dr. A. Chockalingam Dept of ECE, IISc, Bangalore PhCH#1 PhCH#2

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 Dr. A. Chockalingam Dept of ECE, IISc, Bangalore

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 < 40 bits when Turbo code is used Dr. A. Chockalingam Dept of ECE, IISc, Bangalore

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

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 Dr. A. Chockalingam Dept of ECE, IISc, Bangalore

Multiplexing & Channel Coding (..cntd) Radio Frame Segmentation when TTI > 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 Dr. A. Chockalingam Dept of ECE, IISc, Bangalore

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 Dr. A. Chockalingam Dept of ECE, IISc, Bangalore

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 Dr. A. Chockalingam Dept of ECE, IISc, Bangalore

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 Dr. A. Chockalingam Dept of ECE, IISc, Bangalore

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 > threshold Zero rate TF: if ratio Pd/Pc < 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 Dr. A. Chockalingam Dept of ECE, IISc, Bangalore

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 Dr. A. Chockalingam Dept of ECE, IISc, Bangalore

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 Dr. A. Chockalingam Dept of ECE, IISc, Bangalore

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 DATA 1 TPC TFCI DATA 2 Pilot DPDCH DPCCH DPDCH DPCCH Dr. A. Chockalingam Dept of ECE, IISc, Bangalore

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 Dr. A. Chockalingam Dept of ECE, IISc, Bangalore

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 Kb/s 15 Ks/s Kb/s 30 Ks/s Kb/s 60 Ks/s Kb/s 120 Ks/s Kb/s 240 Ks/s Kb/s 480 Ks/s Kb/s 960 Ks/s Kb/s Dr. A. Chockalingam Dept of ECE, IISc, Bangalore

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 SF=256 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) Dr. A. Chockalingam Dept of ECE, IISc, Bangalore

Common D/L Physical Channels Common Control Physical CHannel (CCPCH) Primary CCPCH (P-CCPCH) 30 Kbps fixed rate channel with SF=256 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 Dr. A. Chockalingam Dept of ECE, IISc, Bangalore

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 cell’s DL scrambling code belongs to Dr. A. Chockalingam Dept of ECE, IISc, Bangalore

D/L Spreading I DL Physical Channel data Serial to Parallel Conv. I+jQ 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 Dr. A. Chockalingam Dept of ECE, IISc, Bangalore

Scrambling Codes # possible D/L scrambling codes = 2**18 -1 = 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 Dr. A. Chockalingam Dept of ECE, IISc, Bangalore

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 2nd Insertion of DTX Indication CCTrCH Physical Channel Segmentation 2nd interleaving Physical Channel Mapping Dr. A. Chockalingam Dept of ECE, IISc, Bangalore PhCH#1 PhCH#2

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 Dr. A. Chockalingam Dept of ECE, IISc, Bangalore

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 Dr. A. Chockalingam Dept of ECE, IISc, Bangalore

WCDMA Physical Channels P-CCPCH S-CCPCH DPDCH DPCCH PDSCH PCPCH PRACH UE BS AICH P-SCH S-SCH CSICH CPICH PICH CD/CA-ICH Dr. A. Chockalingam Dept of ECE, IISc, Bangalore

Channel Mapping on the U/L Logical Channels CCCH DTCH DCCH Transport Channels RACH DCH CPCH Physical Channels PRACH DPDCH DPCCH PCPCH Dr. A. Chockalingam Dept of ECE, IISc, Bangalore

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 Dr. A. Chockalingam Dept of ECE, IISc, Bangalore

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