7072747 UMTS Physical Layer

8/14/2019 7072747 UMTS Physical Layer

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WCDMA Physical Layer Design

A. Chockalingam

Assistant Professor

Indian Institute of Science, Bangalore-12

[email protected]

http://ece.iisc.ernet.in/~achockal


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Dr. A. Chockalingam Dept of ECE, IISc, Bangalore 2

Outline

x WCDMA Network ArchitectureWCDMA Network Architecture

x WCDMA Physical LayerWCDMA Physical Layer

Physical / Transport / Logical ChannelsPhysical / Transport / Logical Channels

UplinkUplink

Spreading - Channelisation / ScramblingSpreading - Channelisation / Scrambling

Transport Formats and ConfigurationTransport Formats and Configuration

Multiplexing and Channel CodingMultiplexing and Channel Coding

DownlinkDownlink

Spreading / Scrambling / ChannelisationSpreading / Scrambling / Channelisation

Multiplexing and Channel CodingMultiplexing and Channel Coding


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2G to 3G Evolution

IS-95AIS-95A IS-95BIS-95B cdma2000cdma2000

IMT2000IMT2000

IMT2000: ITUs Standardization Effort towards 3GIMT2000: ITUs Standardization Effort towards 3G

(IMT-2000 previously termed as FPLMTS)

UMTS:UMTS: European Effort (Specified by 3G Partnership Project 3GPP)

GSMGSM GPRSGPRS

WCDMAWCDMA

EDGEEDGE

DD

AA

TT

AA

II

SS

99

99


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UMTS NW Model

USIMMobile

Equipment

Access

Network

Serving

Network

PS/CS

Transit

Network

CuCu UuUu IuIu YuYu

User EquipmentUser Equipment Access NetworkAccess Network Core NetworkCore Network

InfrastructureInfrastructure

Home

Network

Access StratumAccess Stratum(Protocols between UE and Access NW)

Non-access StratumNon-access Stratum(Protocols between UE and Core NW)

ZuZu

Stratum:Stratum: Refers to a way of

grouping protocols handling activities


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UMTS NW Architecture

Node B

UE

UE

UE

Node B

Node B

Node B

RNC

RNC

UTRAN

RNS

RNS

CN

CN (CS Domain)

CN (PS Domain)

SGSN GGSN

Registers

HLR/AuC/EIR(Home Network)

3G MSC

/ VLR

3G

GMSC

UuUu IuIu

IurIur

IubIub


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WCDMA System Features

x UTRA FDD mode and TDD modeUTRA FDD mode and TDD mode

x UTRA FDD featuresUTRA FDD features

Multiple Access:Multiple Access: CDMACDMA

Channel Spacing:Channel Spacing: 5 MHz5 MHz

Chip Rate:Chip Rate: 3.84 Mcps3.84 Mcps

Frame Length:Frame Length: 10 msec10 msec

Time Slots:Time Slots: 15 slots per 10 msec frame15 slots per 10 msec frame

Spreading Factor:Spreading Factor: 4 to 5124 to 512

Multi-rate:Multi-rate: Through Multi-code orThrough Multi-code or

Orthogonal Variable SpreadingOrthogonal Variable Spreading


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UTRA FDD Features

FEC Codes:FEC Codes: Rate 1/2, 1/3 convolutional codeRate 1/2, 1/3 convolutional codewith constraint length K = 9with constraint length K = 9

Rate 1/3, 8-state Turbo codingRate 1/3, 8-state Turbo coding

Interleaving:Interleaving: Intra- or Inter-frame interleavingIntra- or Inter-frame interleaving

(10, 20 40, 80 msec)(10, 20 40, 80 msec) Modulation:Modulation: QPSKQPSK

Detection:Detection: Coherent based on pilot symbolsCoherent based on pilot symbols

Micro diversity:Micro diversity: RAKE in BS and UERAKE in BS and UE

Power Control:Power Control: Fast closed-loop at 1500 Hz rateFast closed-loop at 1500 Hz rate Intra-frequency HO: Soft / Softer HandoverIntra-frequency HO: Soft / Softer Handover

Inter-frequency HO: Hard HandoverInter-frequency HO: Hard Handover

Interference Cancellation: Support for multiuser detectionInterference Cancellation: Support for multiuser detection


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Radio Interface Protocol Model

PHYPHY

MACMAC

RLCRLC

Transport ChannelsTransport Channels

Logical ChannelsLogical Channels

User PlaneUser Plane

Radio BearersRadio BearersSignallingSignalling

Radio BearersRadio Bearers

PDCPPDCPBMCBMC

RRCRRC

USER PLANEUSER PLANECONTROL PLANECONTROL PLANE

ControlControl

L1L1(Radio Physical Layer)(Radio Physical Layer)

L2L2(Radio Link Layer)(Radio Link Layer)

L3L3(Radio Network Layer)(Radio Network Layer)U-Plane Radio BearersU-Plane Radio Bearers


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WCDMA Radio Channels

x

Physical ChannelsPhysical Channels Transmission media.Transmission media.

Two types of physical channels defined in L1; FDD and TDD.Two types of physical channels defined in L1; FDD and TDD.

FDD is characterized by frequency, code, I/Q phaseFDD is characterized by frequency, code, I/Q phase

Follow a layered structure of radio frames and time slotsFollow a layered structure of radio frames and time slots

x Transport ChannelsTransport Channels describes the way information is transferred over the radio interfacedescribes the way information is transferred over the radio interface

x Logical ChannelsLogical Channels the type of information transferred characterizes a logical channelthe type of information transferred characterizes a logical channel

UE BS RNC

Logical ChannelsLogical Channels

Transport ChannelsTransport Channels

Physical ChannelsPhysical Channels


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Physical Channels

x Corresponds to a specific carrier frequency,Corresponds to a specific carrier frequency,

code, relative phase in I and Q branchescode, relative phase in I and Q branches

x Dedicated and Common Physical ChannelsDedicated and Common Physical Channels

x Layered structure of radio frames and time slotsLayered structure of radio frames and time slotsx A radio frame = 10 msec = 15 slots/frameA radio frame = 10 msec = 15 slots/frame

x 1 frame = 38400 chips, 1 slot = 2560 chips1 frame = 38400 chips, 1 slot = 2560 chips

x

Slot configuration varies depending on theSlot configuration varies depending on thechannel bit rate of the physical channelchannel bit rate of the physical channel

# bits/slot different for different physical channels# bits/slot different for different physical channels

may vary with time (on a frame by frame basis)may vary with time (on a frame by frame basis)


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U/L Physical Channels

x Dedicated U/L ChannelsDedicated U/L Channels DPDCHDPDCH

DPCCHDPCCH

x Common U/L ChannelsCommon U/L Channels PRACHPRACH

Preamble partPreamble part

Message partMessage part PCPCHPCPCH

Preamble partPreamble part Message partMessage part


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Dedicated U/L Physical Channels

x

Two typesTwo types

Dedicated Physical Data CHannel (DPDCH)Dedicated Physical Data CHannel (DPDCH)

Dedicated Physical Control CHannel (DPCCH)Dedicated Physical Control CHannel (DPCCH)

Both are I/Q code multiplexed within each radio frameBoth are I/Q code multiplexed within each radio frame

x

U/L DPDCH carries the DCH transport channelU/L DPDCH carries the DCH transport channelx U/L DPCCH carries L1 control bits such asU/L DPCCH carries L1 control bits such as

Pilot bitsPilot bits(to enable channel estimation for coherent detection at BS)(to enable channel estimation for coherent detection at BS)

Transmit power control (TPC)Transmit power control (TPC) commandscommands

Feedback Information (FBI)Feedback Information (FBI) used for CL transmit diversity and Site Selection Diversityused for CL transmit diversity and Site Selection DiversityTransmission (SDTC)Transmission (SDTC)

Transport Format Combination Indicator (TFCI)Transport Format Combination Indicator (TFCI) for several simultaneous services. Informs the rx of the transportfor several simultaneous services. Informs the rx of the transport

format combination of the transport channels mapped to DPDCHformat combination of the transport channels mapped to DPDCH


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U/L Frame Structure

x

There is only one U/L DPCCH on each radio linkThere is only one U/L DPCCH on each radio linkx There can be 0, 1, or several DPDCHs on each radio linkThere can be 0, 1, or several DPDCHs on each radio link

x 10 msec frames divided into 15 slots10 msec frames divided into 15 slots

S0S0 S1S1 S2S2 S3S3 S13S13 S14S14

1 Frame = 15 slots = 10 msec1 Frame = 15 slots = 10 msec

DATADATA1 time slot = 2/3 msec1 time slot = 2/3 msecDPDCHDPDCH

(on I-Chl)(on I-Chl)

PilotPilotDPCCHDPCCH

(on Q-Chl)(on Q-Chl)TFCITFCI FBIFBI TPCTPC

10 bits = 2560 chips => SF = 25610 bits = 2560 chips => SF = 256

(N(Ndatadata bits)bits)


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I, Q Spreading for DPDCH, DPCCH

DPDCH-1DPDCH-1

DPDCH-3DPDCH-3

CCd,1d,1

CCd,3d,3 BBdd

BBddII

DPDCH-2DPDCH-2

DPCCH-2DPCCH-2

CCd,2d,2

CCcc BBcc

BBdd QQ

I+jQI+jQ

SSdpch,ndpch,n

CCc,c, CCd,n:d,n: Channelization codesChannelization codesSdpch,n: Scrambling codeSdpch,n: Scrambling code

BBd,d, BBc:c: Gain factorsGain factors

Up to 6 DPDCHs in parallelUp to 6 DPDCHs in parallel

jj


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WCDMA Channelisation Codes

x Orthogonal codesOrthogonal codes

x Used for channel separation both in U/L and D/LUsed for channel separation both in U/L and D/L

directionsdirections

x Can have different spreading factor values (thusCan have different spreading factor values (thus

support different symbol rates)support different symbol rates)

x CCch,SF,kch,SF,k : SF - Spreading Factor, k is the code: SF - Spreading Factor, k is the code

number 0


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U/L Channelization Codes

x Orthogonal Variable Spreading Factor (OVSF)Orthogonal Variable Spreading Factor (OVSF)

channelization codeschannelization codes

x Separates data / control channels from same UESeparates data / control channels from same UE

x Preserves orthogonality between these channelsPreserves orthogonality between these channels

(1)(1)

(1,1)(1,1)

(1,-1)(1,-1)

(1,1,1,1)(1,1,1,1)

(1,1,-1,-1)(1,1,-1,-1)

(1,-1,1,-1)(1,-1,1,-1)

(1,-1,-1,1)(1,-1,-1,1)

SF=1SF=1SF=2SF=2

SF=4SF=4

C(SF,k)C(SF,k)

SF: Spreading FactorSF: Spreading Factor

k: code number 0


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U/L Scrambling Codes

x

Use complex valued scrambling codeUse complex valued scrambling codex Long scrambling sequences (2^24)Long scrambling sequences (2^24)

Gold sequences (linear combination of two m-sequences)Gold sequences (linear combination of two m-sequences)

x Short scrambling sequences (2^24)Short scrambling sequences (2^24) from a family sequence of periodically extended S(2)from a family sequence of periodically extended S(2)

codescodes

x

Long or short sequences for DPCCH / DPDCHLong or short sequences for DPCCH / DPDCHx Only long sequences for message parts of PRACHOnly long sequences for message parts of PRACH

and PCPCHand PCPCH


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WCDMA Code Types

x Scrambling Codes, Channelisation CodesScrambling Codes, Channelisation Codes

UplinkUplink DownlinkDownlink

Scrambling codesScrambling codes User separationUser separation Cell separationCell separation

ChannelisationChannelisation Data and ControlData and Control Users within aUsers within acodescodes channels from thechannels from the cellcell

same terminalsame terminal

Spreading code = Scrambling code x Channelisation codeSpreading code = Scrambling code x Channelisation code


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Common U/L Physical Channels

x

Two TypesTwo Types Physical Random Access CHannel (PRACH)Physical Random Access CHannel (PRACH)

Physical Common Packet CHannel (PCPCH)Physical Common Packet CHannel (PCPCH)

x Physical Random Access CHannel (PRACH)Physical Random Access CHannel (PRACH)

carries RACHcarries RACH Uses S-ALOHA technique with fast Acquisition IndicationUses S-ALOHA technique with fast Acquisition Indication Access slots (15 access slots per 2 frames)Access slots (15 access slots per 2 frames)

RA transmission consists ofRA transmission consists of

several 4096 chip preambles (uses 256 repetitions of 16 chipsseveral 4096 chip preambles (uses 256 repetitions of 16 chipssignature sequence) and 1or 2 frame messagesignature sequence) and 1or 2 frame message

PreamblePreamble Message Part (1 or 2 frames)Message Part (1 or 2 frames)

4096 Chips4096 Chips

PreamblePreamble


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Random Access

UEUE BSBS

PRACH: Preamble sent (initial access)PRACH: Preamble sent (initial access)

No detection on AICHNo detection on AICH

PRACH: Preamble sent (initial access)PRACH: Preamble sent (initial access)

AICH: Preamble sent detectedAICH: Preamble sent detected

PRACH: Random Access Info sentPRACH: Random Access Info sent


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Common U/L Physical Channels

x Physical Common Packet CHannel (PCPCH)Physical Common Packet CHannel (PCPCH) Carries CPCHCarries CPCH

CPCH is based on DSMA-CD technique with fastCPCH is based on DSMA-CD technique with fast

Acquisition IndicationAcquisition Indication

Access slot timing and structure are identical to thoseAccess slot timing and structure are identical to those

defined for RACHdefined for RACH

Transmission consists ofTransmission consists of

Access preamble(s) - one or several each 4096 chipsAccess preamble(s) - one or several each 4096 chips

Collision Detection preambleCollision Detection preamble

DPCCH Power Control Preamble (0 or 8 slots)DPCCH Power Control Preamble (0 or 8 slots)

Message of variable length (Nx10 msec)Message of variable length (Nx10 msec)

PCPCH good for carrying small sized bursty dataPCPCH good for carrying small sized bursty data


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Transport Formats / Configurations

x Transport BlockTransport Block (TB)(TB) Basic unit of data exchanged between L1 & MAC for L1Basic unit of data exchanged between L1 & MAC for L1

processingprocessing

x Transport Block Size:Transport Block Size: Number of bits in a TB.Number of bits in a TB.

x Transport Block SetTransport Block Set (TBS)(TBS) A set of TBs exchanged between L1 and MAC at the sameA set of TBs exchanged between L1 and MAC at the same

time instant using the same transport channeltime instant using the same transport channel

x Transport Block Set Size:Transport Block Set Size:Number of bits in a TBSNumber of bits in a TBS

x Transmission Time IntervalTransmission Time Interval (TTI)(TTI) Periodicity at which a TBS is transferred by the physical layerPeriodicity at which a TBS is transferred by the physical layer

on to the radio interface - {10, 20, 40, 80 ms}on to the radio interface - {10, 20, 40, 80 ms}

MAC delivers one TBS to the physical layer every TTIMAC delivers one TBS to the physical layer every TTI


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x Transport FormatTransport Format (TF)(TF) Format offered by L1 to MAC (and vice versa) for the delivery of aFormat offered by L1 to MAC (and vice versa) for the delivery of a

TBS during a TTI on a given transport channel (TrCH)TBS during a TTI on a given transport channel (TrCH)

Dynamic part (TB size, TBS size)Dynamic part (TB size, TBS size)

Semi-static part (TTI, type/rate of coding,size of CRC)Semi-static part (TTI, type/rate of coding,size of CRC)

TB size, TBS size, TTI define the TrCH bit rateTB size, TBS size, TTI define the TrCH bit rate before L1 processingbefore L1 processing

e.g., TB size = 336 bits (320 bit payload + 16 bits RLC header)e.g., TB size = 336 bits (320 bit payload + 16 bits RLC header)

TBS size = 2 TBs per TTI, TTI = 10 msTBS size = 2 TBs per TTI, TTI = 10 ms

DCH Bit rate (with RLC header) = 336*2/10 = 67.2 KbpsDCH Bit rate (with RLC header) = 336*2/10 = 67.2 Kbps

User Bit rate (without RLC header) = 320*2/10 = 64 KbpsUser Bit rate (without RLC header) = 320*2/10 = 64 Kbps

Variable bit rate can be achieved by changing (Variable bit rate can be achieved by changing (between TTIsbetween TTIs))

either the TBS size only, or both the TB size and TBS Sizeeither the TBS size only, or both the TB size and TBS Size

x Transport Format SetTransport Format Set (TFS)(TFS) a set of TFs associated with a TrCHa set of TFs associated with a TrCH semi-static part of all TFs in a TFS is the samesemi-static part of all TFs in a TFS is the same


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x Transport Format CombinationTransport Format Combination (TFC)(TFC) Multiple TrCHs each having a TFMultiple TrCHs each having a TF

Authorized combination of the currently valid TFs that can beAuthorized combination of the currently valid TFs that can besubmitted to L1 on asubmitted to L1 on a CCTrCHCCTrCH, containing one TF from each TrCH, containing one TF from each TrCH

x Transport Format Combination SetTransport Format Combination Set (TFCS)(TFCS)

A set of TFCs on a CCTrCH. Produced by RNCA set of TFCs on a CCTrCH. Produced by RNC TFCS is given to MAC by L3 for controlTFCS is given to MAC by L3 for control

MAC chooses between the different TFCs specified in the TFCSMAC chooses between the different TFCs specified in the TFCS

MAC has control over only the dynamic part of the TFs. Semi-static partMAC has control over only the dynamic part of the TFs. Semi-static partrelates to QoS (e.g., quality) and is controlled by RNC admission controlrelates 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 signalingBit rate can be changed quickly by MAC with no need to L3 signaling

x Transport Format IndicatorTransport Format Indicator(TFI)(TFI) A label for a specific TF within a TFS. Used between MAC and L1A label for a specific TF within a TFS. Used between MAC and L1

x Transport Format Combination IndicatorTransport Format Combination Indicator(TFCI)(TFCI) Used to inform the receiving side of the currently valid TFCUsed to inform the receiving side of the currently valid TFC


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TTITTI TTITTI TTITTI

TTITTI TTITTI TTITTI

TBTBDCH1DCH1

DCH2DCH2

TBTB TBTB

TBTB TBTB TBTB

TBTB

Transport Block SetTransport Block Set(TBS)(TBS)

TBTB

TBTB

Transport Format (TF)Transport Format (TF)Transport FormatTransport Format

Set (TFS)Set (TFS)

Transport FormatTransport FormatCombination (TFC)Combination (TFC)

Transport FormatTransport Format

Combination SetCombination Set

(TFCS)(TFCS)


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TFI and TFCI (Transmitter)

Transport Chl 1Transport Chl 1 Transport Chl 2Transport Chl 2

TransportTransport

BlockBlockTransportTransport

BlockBlock

TransportTransportBlockBlock

TransportTransportBlockBlock

TFITFI TFITFI

TFCITFCI Coding andCoding andMultiplexingMultiplexing

PhysicalPhysical

LayerLayer

HigherHigherLayerLayer

DPCCH (Q-Chl)DPCCH (Q-Chl) DPDCH (I-Chl)DPDCH (I-Chl)

PhysicalPhysical

Control ChlControl ChlPhysicalPhysical

Data ChlData Chl

E.g: Two transport channels mapped to a single physical channelE.g: Two transport channels mapped to a single physical channel

This dotted lineThis dotted line

represents the Iur interfacerepresents the Iur interface

in case of NW sidein case of NW side


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TFI and TFCI (Receiver)

Transport Chl 1Transport Chl 1 Transport Chl 2Transport Chl 2

TransportTransport

Block & EIBlock & EITransportTransport

Block & EIBlock & EI

TransportTransportBlock & EIBlock & EI

TransportTransportBlock & EIBlock & EI

TFITFI TFITFI

TFCITFCIDecodeDecode

Decoding andDecoding andDemultiplexingDemultiplexing

PhysicalPhysical

LayerLayer

HigherHigherLayerLayer

DPCCH (Q-Chl)DPCCH (Q-Chl) DPDCH (I-Chl)DPDCH (I-Chl)

EI: ErrorEI: ErrorIndicationIndication

PhysicalPhysical

Control ChlControl ChlPhysicalPhysical

Data ChlData Chl


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TFI and TFCI

x Each transport channel is accompanied by aEach transport channel is accompanied by a TFITFI at eachat eachtime event at which data is expected to arrive from HLtime event at which data is expected to arrive from HL

x Physical layer combines the TFI info from differentPhysical layer combines the TFI info from differenttransport channels to the TFCItransport channels to the TFCI

x TFCI is sent on the DPCCH to inform the receiver aboutTFCI is sent on the DPCCH to inform the receiver aboutthe instantaneousthe instantaneous transport format combinationtransport format combination of theof the

transport channels mapped to the U/L DPDCHtransport channels mapped to the U/L DPDCH

transmitted simultaneouslytransmitted simultaneously


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Transport Format (e.g., Speech)

x Conversational Speech (12 Kbps)Conversational Speech (12 Kbps)

12.2 Kbps max.12.2 Kbps max.

TTI: 20 msecTTI: 20 msec

Transport Formats (TF) available:Transport Formats (TF) available:

TF RAB1 RAB2 RAB3TF RAB1 RAB2 RAB3

TF0v 0 x 81 0 x 103 0 x 60 (e.g., silence)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)TF1v 1 x 81 1 x 103 1 x 60 (e.g, active voice)

two other formats too (see Stds. Doc.)two other formats too (see Stds. Doc.)

TFC: (TF0, TF0, TF0) e.g., during silenceTFC: (TF0, TF0, TF0) e.g., during silence

(TF1, TF1, TF1) e.g., during active voice periods(TF1, TF1, TF1) e.g., during active voice periods


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Transport Format (e.g., Data)

x Interactive/Background Data (64 Kbps)Interactive/Background Data (64 Kbps)

64 Kbps max.64 Kbps max.

TTI: 20 msecTTI: 20 msec

Transport Block (TB) size = 336 bitsTransport Block (TB) size = 336 bits

Transport Formats (TF) available:Transport Formats (TF) available:

TF0 - 0 x 336TF0 - 0 x 336

TF1 - 1 x 336TF1 - 1 x 336

TF2 - 2 x 336TF2 - 2 x 336

TF3 - 3 x 336TF3 - 3 x 336

TF4 - 4 x 336TF4 - 4 x 336


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Transport Format (Speech + Data)

x Conversational speech (12 Kbps) +Conversational speech (12 Kbps) +Interactive/Background Data (64 Kbps)Interactive/Background Data (64 Kbps)

Voice TrCH Data TrCHVoice TrCH Data TrCH

TFC1: (TF0v, TF0v, TF0v) TF0dTFC1: (TF0v, TF0v, TF0v) TF0d

TFC2: (TF0v, TF0v, TF0v) TF1dTFC2: (TF0v, TF0v, TF0v) TF1dTFC3: (TF0v, TF0v, TF0v) TF2dTFC3: (TF0v, TF0v, TF0v) TF2d









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Multiplexing & Channel Coding

x

Data arrives at the coding/mux unit in transport block sets,Data arrives at the coding/mux unit in transport block sets,

once every transmission time interval (TTI)once every transmission time interval (TTI)x TTI depends on the transport channel; {10, 20, 40, 80 ms})TTI depends on the transport channel; {10, 20, 40, 80 ms})x Main stepsMain steps

Add CRC to each blockAdd CRC to each block

transport block concatenation and block segmentationtransport block concatenation and block segmentation channel codingchannel coding

first interleaving (per TTI)first interleaving (per TTI) radio frame segmentation (when TTI > 10 ms)radio frame segmentation (when TTI > 10 ms) rate matching (repetition or puncturing)rate matching (repetition or puncturing) multiplexing of transport channels (CCTrCH)multiplexing of transport channels (CCTrCH) insertion of DTX indication bitsinsertion of DTX indication bits physical channel segmentationphysical channel segmentation second interleaving (per radio frame, ie., among bits in 1 radio frame)second interleaving (per radio frame, ie., among bits in 1 radio frame) mapping to physical channelmapping to physical channel


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Multiplexing & Channel Coding (U/L)

CRC Attachment

TrBk Concatenation/

Code Block Segmentation

Channel Coding

Radio Frame Equalization

1st InterleavingRadio Frame Segmentation

Rate Matching

CCTrCHCCTrCH

CRC Attachment

TrBk Concatenation/


Channel Coding

Radio Frame Equalization

1st InterleavingRadio Frame Segmentation

Rate Matching

TrCH-2TrCH-2

TrCH Multiplexing

Physical Channel Segmentation

2nd interleaving

TrCH-1TrCH-1

Physical Channel Mapping

PhCH#2PhCH#2PhCH#1PhCH#1


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Multiplexing & Channel Coding (..cntd)

x Applicable to DCH, RACH, CPCH, DSCH, BCH,Applicable to DCH, RACH, CPCH, DSCH, BCH,

FACH, PCHFACH, PCH

x CRCCRC

add CRC to each transport block for error detectionadd CRC to each transport block for error detection

CRC calculated on entire transport blockCRC calculated on entire transport block

Size of CRC: 24, 16, 12, 8, 0 bitsSize of CRC: 24, 16, 12, 8, 0 bits

what CRC size is used for each TrCH is signaled fromwhat CRC size is used for each TrCH is signaled fromhigher layershigher layers


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x

TrBk Concatenation & Code Block SegmentationTrBk Concatenation & Code Block Segmentation all transport blocks in a TTI are concatenatedall transport blocks in a TTI are concatenated

if no. of bits in a TTI after concatenation (X) is greater thanif no. of bits in a TTI after concatenation (X) is greater than

the maximum size of the code block (in the channel codingthe maximum size of the code block (in the channel coding

block), then code block segmentation is doneblock), then code block segmentation is done

max. size of the code block (Z) depends on whethermax. size of the code block (Z) depends on whether

Convolutional code ( Z = 504 bits) orConvolutional code ( Z = 504 bits) or

Turbo code ( Z = 5114 bits) is used for the TrCHTurbo code ( Z = 5114 bits) is used for the TrCH

Code blocks after segmentation are of the same sizeCode blocks after segmentation are of the same size

Filler bits (zeros) added to 1st coded block toFiller bits (zeros) added to 1st coded block to

to make integer number of code blocks, orto make integer number of code blocks, or

if X < 40 bits when Turbo code is usedif X < 40 bits when Turbo code is used


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x Channel CodingChannel Coding

Coding SchemeCoding Scheme Coding RateCoding RateType of TrCHType of TrCH

BCHBCH

PCHPCH

RACHRACH

DPCH, DCH,DPCH, DCH,

DSCH, FACHDSCH, FACH

ConvolutionalConvolutional

CodingCoding(constraint(constraint

length = 9)length = 9)

Turbo CodingTurbo Coding 1/31/3

1/3, 1/21/3, 1/2

1/21/2

If number of coded blocks is greater than 1, they areIf number of coded blocks is greater than 1, they are

serially concatenatedserially concatenated


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x Radio Frame EqualizationRadio Frame Equalization padding the input bit sequence in order to ensure thatpadding the input bit sequence in order to ensure that

the output can be segmented into data segments ofthe output can be segmented into data segments of

equal sizeequal size

I.e., number of bits per segment is same after radioI.e., number of bits per segment is same after radio

frame equalizationframe equalization

performed only on the U/Lperformed only on the U/L

x 1st Interleaving1st Interleaving block interleaverblock interleaver

among bits in a TTIamong bits in a TTI


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x

Radio Frame SegmentationRadio Frame Segmentation when TTI > 10 msec, input bit sequence is segmentedwhen TTI > 10 msec, input bit sequence is segmentedand mapped on to Fi consecutive radio framesand mapped on to Fi consecutive radio frames

x Rate MatchingRate Matching

means that bits on a transport channel are repeated ormeans that bits on a transport channel are repeated orpuncturedpunctured to ensure that the total bit rate after TrCHto ensure that the total bit rate after TrCHmultiplexing is identical to the total channelmultiplexing is identical to the total channelbit ratebit rateof the allocated dedicated physical channelsof the allocated dedicated physical channels

higher layers assign a rate-matching (semi-static)higher layers assign a rate-matching (semi-static)

attribute for each transport channelattribute for each transport channel

this attribute is used to calculate the number of bits tothis attribute is used to calculate the number of bits to

repeat or puncture, spreading factor, number of PhCHsrepeat or puncture, spreading factor, number of PhCHs

needed, rate matching patternneeded, rate matching pattern


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x

TrCH MultiplexingTrCH Multiplexing every 10 msec, one radio frame from each TrCH isevery 10 msec, one radio frame from each TrCH is

delivered to the TrCH multiplexingdelivered to the TrCH multiplexing

these radio frames are serially concatenated into athese radio frames are serially concatenated into a

coded composite transport channelcoded composite transport channel(CCTrCH)(CCTrCH)

x Physical Channel SegmentationPhysical Channel Segmentation

when more than once PhCH is used, the physicalwhen more than once PhCH is used, the physical

channel segmentation divides the bits among differentchannel segmentation divides the bits among differentPhCHsPhCHs

x 2nd Interleaving2nd Interleaving

among bits within a radio frameamong bits within a radio frame


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x

Insertion of Discontinuous Transmission (DTX)Insertion of Discontinuous Transmission (DTX)Indication BitsIndication Bits

only on the D/Lonly on the D/L

used to fill up the radio frame with bitsused to fill up the radio frame with bits

insertion point depends on whetherinsertion point depends on whetherfixed positionsfixed positions (1st(1stInsertion)Insertion) ororflexible positionsflexible positions (2nd Insertion)(2nd Insertion) of theof the

TrCHs in the radio frame are usedTrCHs in the radio frame are used

During connection setup, NW decides if fixed or flexibleDuring connection setup, NW decides if fixed or flexible

position is used for each CCTrCHposition is used for each CCTrCH

DTX Indication bits are not transmitted; they only tellDTX Indication bits are not transmitted; they only tell

when the Tx must be turned offwhen the Tx must be turned off


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x Transport Format DetectionTransport Format Detection TFCI Based DetectionTFCI Based Detection

Explicit Blind DetectionExplicit Blind Detection

using receive power ratiousing receive power ratio

by use of channel decoding and CRC checkby use of channel decoding and CRC check

Guided DetectionGuided Detection

Explicit blind detection used on Guiding TrCHExplicit blind detection used on Guiding TrCH Guiding TrCH has the same TTI as the TrCH underGuiding TrCH has the same TTI as the TrCH under

considerationconsideration


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x Blind Transport Format DetectionBlind Transport Format Detection Using Received Power Ratio (for the case of 2 TFs)Using Received Power Ratio (for the case of 2 TFs)

Ratio of the power received on DPDCH (Pd) and DPCCH (Pc)Ratio of the power received on DPDCH (Pd) and DPCCH (Pc)

Full Rate TF: if ratio Pd/Pc > thresholdFull Rate TF: if ratio Pd/Pc > threshold

Zero rate TF: if ratio Pd/Pc < thresholdZero rate TF: if ratio Pd/Pc < threshold

Using CRC (for the case of multiple TFs)Using CRC (for the case of multiple TFs)

Receiver knows only the possible TFs or end bit (thru L3 signaling)Receiver knows only the possible TFs or end bit (thru L3 signaling)

Receiver performs FEC (Viterbi) decodingReceiver performs FEC (Viterbi) decoding

path metric selection among the surviving paths in the decodingpath metric selection among the surviving paths in the decoding


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D/L Physical Channels

x

Dedicated D/L ChannelsDedicated D/L Channels DPDCHDPDCH

DPCCHDPCCH

x Common D/L ChannelsCommon D/L Channels

Common PIlot CHannel (CPICH)Common PIlot CHannel (CPICH) Primary CPICHPrimary CPICH

Secondary CPICHSecondary CPICH

Common Control Physical CHannel (CCPCH)Common Control Physical CHannel (CCPCH)

Primary CCPCH,Primary CCPCH,

Secondary CCPCHSecondary CCPCH

Synchronization CHannel (SCH)Synchronization CHannel (SCH) Primary SCH,Primary SCH,

Secondary SCHSecondary SCH


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Dedicated D/L Physical Channels

x Dedicated Physical CHannel (D/L DPCH)Dedicated Physical CHannel (D/L DPCH) transmits dedicated data generated at L2 and abovetransmits dedicated data generated at L2 and above

time-multiplexes with L1 control bits (Pilot, TPC,time-multiplexes with L1 control bits (Pilot, TPC,

TFCI)TFCI)

x D/L DPCHD/L DPCH

Time-multiplex of a D/L DPDCH and a D/L DPCCHTime-multiplex of a D/L DPDCH and a D/L DPCCH


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DL Frame Structure

S0S0

x

10 msec frames divided into 15 slots10 msec frames divided into 15 slots

x No. of bits in different DPDCH field (Npilot, Ntpc, Ntfci, Ndata1,No. of bits in different DPDCH field (Npilot, Ntpc, Ntfci, Ndata1,

Ndata2) are given in tablesNdata2) are given in tables

x Which slot format to use is configured (and reconfigured) byWhich slot format to use is configured (and reconfigured) by

higher layershigher layers

S1S1 S2S2 S3S3 S13S13 S14S14

1 Frame = 15 slots = 10 msec1 Frame = 15 slots = 10 msec

DATA 1DATA 1

1 time slot = 2/3 msec1 time slot = 2/3 msec

DPDCHDPDCH

PilotPilot

DPCCHDPCCH

TFCITFCITPCTPC DATA 2DATA 2

DPDCHDPDCH DPCCHDPCCH


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D/L Transmission

x Multicode Transmission on D/LMulticode Transmission on D/L Multicode transmission can be employed on the D/LMulticode transmission can be employed on the D/L

I.e., CCTrCH is mapped on to several parallel D/LI.e., CCTrCH is mapped on to several parallel D/L

DPCHs using the same spreading factorDPCHs using the same spreading factor

In this case, L1 control information is sent only on theIn this case, L1 control information is sent only on thefirst downlink DPCHfirst downlink DPCH

x Multiple CCTrCHsMultiple CCTrCHs

In case there are several CCTrCHs mapped to differentIn case there are several CCTrCHs mapped to different

DPCHs transmitted to the same UE, different spreadingDPCHs transmitted to the same UE, different spreading

factors can be used on DPCHsfactors can be used on DPCHs

multiple CCTrCHs feature for future releasemultiple CCTrCHs feature for future release


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WCDMA Transmission Rates (D/L)

x

System Chip Rate : 3.84 McpsSystem Chip Rate : 3.84 Mcpsx Symbol Rates on DownlinkSymbol Rates on Downlink

Symb RateSymb Rate Chl bit rateChl bit rate SFSF

7.5 Ks/s7.5 Ks/s 15 Kb/s 51215 Kb/s 512

15 Ks/s15 Ks/s 30 Kb/s 25630 Kb/s 256

30 Ks/s30 Ks/s 60 Kb/s 12860 Kb/s 128

60 Ks/s 120 Kb/s 6460 Ks/s 120 Kb/s 64

120 Ks/s 240 Kb/s 32120 Ks/s 240 Kb/s 32

240 Ks/s 480 Kb/s 16240 Ks/s 480 Kb/s 16

480 Ks/s 960 Kb/s 8480 Ks/s 960 Kb/s 8

960 Ks/s 1920 Kb/s 4960 Ks/s 1920 Kb/s 4


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Common D/L Physical Channels

x Common Pilot CHannel (CPICH)Common Pilot CHannel (CPICH) 30 Kbps fixed rate channel (SF = 256)30 Kbps fixed rate channel (SF = 256)

Primary CPICHPrimary CPICH Always uses the same channelization codeAlways uses the same channelization code

Scrambled by primary scrambling codeScrambled by primary scrambling code

There is one and only one P-CPICH per cellThere is one and only one P-CPICH per cell Broadcast over the entire cellBroadcast over the entire cell

Provides a phase reference for several D/L channelsProvides a phase reference for several D/L channels

Secondary CPICHSecondary CPICH Uses an arbitrary channelization code of SF=256Uses an arbitrary channelization code of SF=256

Scrambled either by the primary or a secondary scrambling codeScrambled either by the primary or a secondary scrambling code

A cell may contain 0,1, or several S-CPICHA cell may contain 0,1, or several S-CPICH

Broadcast over entire OR part of a cellBroadcast over entire OR part of a cell

A S-CPICH can be a phase reference to some D/L channelsA S-CPICH can be a phase reference to some D/L channels(which is communicated to the UE thru higher layer signaling)(which is communicated to the UE thru higher layer signaling)


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x Common Control Physical CHannel (CCPCH)Common Control Physical CHannel (CCPCH)

Primary CCPCH (P-CCPCH)Primary CCPCH (P-CCPCH) 30 Kbps fixed rate channel with SF=25630 Kbps fixed rate channel with SF=256

Carries BCH transport channelCarries BCH transport channel No TPC, TFCI, pilot bits are sentNo TPC, TFCI, pilot bits are sent the transport channel mapped to P-CCPCH (I.e., BCH) canthe transport channel mapped to P-CCPCH (I.e., BCH) can

only have a fixed predefined TFConly have a fixed predefined TFC

Secondary CCPCH (S-CCPCH)Secondary CCPCH (S-CCPCH) Carries FACH and PCHCarries FACH and PCH

S-CCPCH can be with TFCI and without TFCIS-CCPCH can be with TFCI and without TFCI

NW decides if TFCI has to be sentNW decides if TFCI has to be sent

So UE should be (mandatory) capable of receiving with orSo UE should be (mandatory) capable of receiving with orwithout TFCI (i.e., blind)without TFCI (i.e., blind)

S-CCPCH can support multiple TFCs using TFCIS-CCPCH can support multiple TFCs using TFCI

Main difference between CCPCHs and Dedicated PhysicalMain difference between CCPCHs and Dedicated Physical

Channels : a CCPCH is NOT inner loop Power ControlledChannels : a CCPCH is NOT inner loop Power Controlled


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x Synchronization CHannel (SCH)Synchronization CHannel (SCH) Downlink signal used for cell searchDownlink signal used for cell search

Consists of Primary and Secondary subchannelsConsists of Primary and Secondary subchannels

Primary SCHPrimary SCH Uses Primary Sychronization Code (PSC), TXUses Primary Sychronization Code (PSC), TXonce every slotonce every slot

PSC is the same for every cell in the systemPSC is the same for every cell in the system

Secondary SCHSecondary SCH Tx in parallel with Primary SCHTx in parallel with Primary SCH

SSC indicates which of the code groups (64SSC indicates which of the code groups (64

groups) the cells DL scrambling code belongs togroups) the cells DL scrambling code belongs to


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D/L Spreading

DL PhysicalDL Physical

Channel dataChannel data CCd,SF,md,SF,mSerial toSerial to

ParallelParallel

Conv.Conv.

II

QQ

I+jQI+jQ

SSdl,ndl,n

jj

Channelisation code: - Differentiate users in a cellChannelisation code: - Differentiate users in a cell

- OVSF- OVSF

- UTRAN assigns channelisation codes to diff. phy. chls- UTRAN assigns channelisation codes to diff. phy. chls

Scrambling Code: Differentiate cellsScrambling Code: Differentiate cells

S bli C d


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Scrambling Codes

x # possible D/L scrambling codes = 2**18 -1 = 262143# possible D/L scrambling codes = 2**18 -1 = 262143x Scrambling codes divided into 512 setsScrambling codes divided into 512 sets

1 primary scrambling code and 15 secondary scrambling codes1 primary scrambling code and 15 secondary scrambling codes

So, there are 512 x 16 = 8192 codesSo, there are 512 x 16 = 8192 codes

x Each cell is allocated one and only primary scrambling codeEach cell is allocated one and only primary scrambling code

The primary CCPCH (Common Control Physical CHannel) is TxThe primary CCPCH (Common Control Physical CHannel) is Tx

always using this primary scrambling codealways using this primary scrambling code

Other D/L physical channels can be Tx with either the PSC or SSCOther D/L physical channels can be Tx with either the PSC or SSCfrom the set associated with the PSC of the cellfrom the set associated with the PSC of the cell


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Multiplexing & Channel Coding (D/L)

CRC Attachment

TrBk Concatenation/


Channel Coding

Rate Matching

1st Insertion of DTX Indication1st Interleaving

Radio Frame Segmentation

CCTrCHCCTrCH

CRC Attachment

TrBk Concatenation/


Channel Coding

Rate Matching

1st Insertion of DTX Indication1st Interleaving

Radio Frame Segmentation

TrCH-2TrCH-2

TrCH Multiplexing

Physical Channel Segmentation

2nd interleaving

TrCH-1TrCH-1

Physical Channel Mapping

PhCH#2PhCH#2PhCH#1PhCH#1

2nd Insertion of DTX Indication

M lti l i & Ch l C di ( td)


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x Physical Channel MappingPhysical Channel Mapping

on U/L: PhCHs are either completely filled or noton U/L: PhCHs are either completely filled or not

used at allused at all

on D/L: No bits in locations with DTX indicationon D/L: No bits in locations with DTX indication

in compressed mode, no bits are mapped to certain slotsin compressed mode, no bits are mapped to certain slots

in a PhCH. Reducing the SF by a factor of 2, 7.5 slotsin a PhCH. Reducing the SF by a factor of 2, 7.5 slots

per frame is used in compressed modeper frame is used in compressed mode

M lti l i & Ch l C di ( td)


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x

Insertion of Discontinuous Transmission (DTX)Insertion of Discontinuous Transmission (DTX)Indication BitsIndication Bits

only on the D/Lonly on the D/L

used to fill up the radio frame with bitsused to fill up the radio frame with bits

insertion point depends on whetherinsertion point depends on whetherfixed positionsfixed positions (1st(1stInsertion)Insertion) ororflexible positionsflexible positions (2nd Insertion)(2nd Insertion) of theof the

TrCHs in the radio frame are usedTrCHs in the radio frame are used

During connection setup, NW decides if fixed or flexibleDuring connection setup, NW decides if fixed or flexible

position is used for each CCTrCHposition is used for each CCTrCH DTX Indication bits are not transmitted; they only tellDTX Indication bits are not transmitted; they only tell

when the Tx must be turned offwhen the Tx must be turned off


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Ch l M i th U/L


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Channel Mapping on the U/L

CCCH DTCH DCCH

RACH DCH CPCH

PRACH DPDCH DPCCH PCPCH

LogicalLogical

ChannelsChannels

TransportTransportChannelsChannels

PhysicalPhysical

ChannelsChannels

Ch l M i th D/L


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Channel Mapping on the D/L

BCCH PCCH CTCH CCCH DCCH DTCH

BCH PCH FACH DCH DSCH

P-CCPCH S-CCPCH DPDCH DPCCH PDSCH

LogicalLogical

ChannelsChannels

TransportTransportChannelsChannels

PhysicalPhysical

ChannelsChannels

Documents

7072747 UMTS Physical Layer