WCDMA Radio Interface Physical Layer (With Comment) ISSUE 1.0

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WCDMA Radio Interface Physical Layerwww.huawei.com

HUAWEI TECHNOLOGIES CO., LTD.

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Chapter 1 Physical Layer Overview Chapter 2 Physical Layer Key Technology Chapter 3 Physical Layer Procedures


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UTRAN Protocol StructureCore Network

IuRNS RNS

Iu

IurRNC Iub NodeB Iub NodeB Iub NodeB RNC Iub NodeB

UTRAN User EquipmentHUAWEI TECHNOLOGIES CO., LTD. All rights reserved Page 2

Radio Interface Protocol StructureGC Nt DC Duplication avoidance

GCC-plane signaling

Nt

DC U-plane informationUuS boundary

RRC control control

control

L3 Radio Bearers PDCP PDCP L2/PDCP

control control

BMC

L2/BMC

RLC

RLC

RLC

RLC RLC RLC RLC

RLC

L2/RLC

Logical Channels MAC L2/MAC Transport Channels L1

PHY


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Spreading Technology Spreading consists of 2 steps

Channelization operation, which transforms data symbols into chips. Thus increasing the bandwidth of the signal, The number of chips per data symbol is called the Spreading FactorSF.The operation is done by multiplying with OVSF code Scrambling operation is applied to the spreading signal

Data bit

Chips after spreading

OVSF code

Scrambling code


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Channelization Code OVSF code is used as channelization code The channelization codes are uniquely described as Cch,SF,k, where SF is the

spreading factor of the code and k is the code number, 0 k SF-1Cch,4,0 =(1,1,1,1) Cch,2,0 = (1,1) Cch,4,1 = (1,1,-1,-1) Cch,1,0 = (1) Cch,4,2 = (1,-1,1,-1) Cch,2,1 = (1,-1) Cch,4,3 = (1,-1,-1,1) SF = 1 SF = 2 SF = 4All rights reserved Page 8


Scrambling Code Scrambling code: GOLD sequence Scrambling code period: 10ms ,or 38400 chips There are 224 long and 224 short uplink scrambling codes For downlink physical channels, a total of 218-1 = 262143 scrambling

codes can be generated. scrambling codes k = 0, 1, , 8191 are used


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Primary Scrambling CodePrimary scrambling code 0Set 0 Scrambling codes for downlink physical channels Secondary scrambling code 1 Secondary scrambling code 15 Primary scrambling code 51116

Set 1

Set 511

8192 scrambling codes

512 sets

Secondary scrambling code 5111615

A primary scrambling code and 15 secondary scrambling codes are included in a set.HUAWEI TECHNOLOGIES CO., LTD. All rights reserved Page 10

Primary Scrambling Code GroupPrimary scrambling code 0 Group 0 Primary scrambling codes for downlink physical channels Group 1 Primary scrambling code 1 Primary scrambling code 7 Primary scrambling code 63 8

Group 63

Primary scrambling code 6387 512 primary scrambling codes 64 primary scrambling code groups Each group consists of 8 primary scrambling codes


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Chapter 2 Physical Layer Key Technology Section 1 Physical Channel Structure and Functions Section 2 Channel Mapping


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WCDMA radio interface has three kinds of channels In terms of protocol layer, the WCDMA radio interface has three channels:

Physical channel, transport channel and logical channel. Logical channel: Carrying user services directly. According to the types of the

carried services, it is divided into two types: Control channel and traffic channel Transport channel: It is the interface of radio interface layer 2 and physical

layer, and is the service provided for MAC layer by the physical layer. According to whether the information transported is dedicated information for a user or common information for all users, it is divided into dedicated channel and common channel Physical channel: It is the ultimate embodiment of all kinds of information when

they are transmitted on radio interfaces. Each kind of channel which uses dedicated carrier frequency, code (spreading code and scrambling code) and carrier phase (I or Q) can be regarded as a dedicated channel


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Logical ChannelDedicated traffic channel Common traffic channel (DTCH) (CTCH) Traffic channel

Broadcast control channel Paging control channel Dedicate control channel Common control channel

(BCCH) (PCCH) (DCCH) (CCCH) Control channel


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Transport ChannelDedicated Channel (DCH)

DCH is an uplink or downlink channel

Dedicated transport channel

Broadcast channel Forward access channel

(BCH) (FACH)

Paging channelRandom access channel

(PCH)(RACH)

Common transport channel

High-speed downlink shared channel (HSDSCH)


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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

(Downlink DPCH) Downlink Common Physical Channel

Common Control Physical Channel (CCPCH) Synchronization Channel Paging Indicator Channel Acquisition Indicator Channel Common Pilot Channel (SCH) (PICH) (AICH) (CPICH)

Downlink Physical Channel

High-Speed Physical Downlink Shared Channel (HS-PDSCH) High-Speed Shared Control Channel (HS-SCCH)HUAWEI TECHNOLOGIES CO., LTD. All rights reserved Page 19

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 Control Channel (HS-DPCCH)

Uplink Physical Channel

Uplink Common Physical Channel

Physical Random Access Channel (PRACH)


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Function of physical channelCell broadcast channelsP-CPICH-Primary Common Pilot Channel S-CPICH-Secondary Common Pilot Channel P-CCPCH-Primary Common Control Physical Channel SCH- Synchronisation Channel

Paging channelsS-CCPCH-Secondary Common Control Physical Channel PICH-Paging Indicator Channel

Random access channels Node BPRACH-Physical Random Access Channel AICH-Acquisition Indicator Channel

UE

Dedicated channelsDPDCH-Dedicated Physical Data Channel DPCCH-Dedicated Physical Control Channel

High speed downlink share channelsHS-SCCH-High Speed Share Control ChannelHS-PDSCH-High Speed Physical Downlink Share Channel HS-DPCCH-High Speed Dedicated Physical Control Channel


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Primary Synchronization Channel (P-SCH) Used for cell search Two sub channels: P-SCH and S-SCH SSC specifies the scrambling code

groups of the cell SSC is chosen from a set of 16 SCH is transmitted at the first 256 chips different codes of length 256, and of every time slot there are altogether 64 SSC PSC is transmitted repeatedly in each sequences correspond to 64 primary time slot scrambling code groupsSlot #0 Slot #1 Slot #14

Primary SCH

ac p ac si,0256 chips 2560 chips

ac p ac si,1

ac p acsi,14

Secondary SCH

One 10 ms SCH radio frame


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Secondary Synchronization Channel (S-SCH)Scrambling Code Group Group 0 Group 1 Group 2 Group 3 Group 4 Group 61 Group 62 Group 63 #0 1 1 1 1 1 9 9 9 #1 1 1 2 2 2 10 11 12 #2 2 5 1 3 16 13 12 10 #3 8 16 15 1 6 10 15 15 #4 9 7 5 8 6 11 12 13 #5 10 3 5 6 11 15 9 14 slot number #6 #7 #8 15 8 10 14 16 3 12 16 6 5 2 5 15 5 12 15 13 9 9 13 14 16 11 15 #9 16 10 11 8 1 12 14 11 #10 #11 #12 #13 #14 2 7 15 7 16 5 12 14 12 10 2 16 11 15 12 4 4 6 3 7 15 12 16 11 2 14 10 11 13 16 13 16 15 12 14 14 16 11 16 10

Slot # ?

Slot #?

Slot #?

P-SCHS-SCH

acp 16256 chips 2560 chips

acp 6

acp 11

..

Group 2 Slot 7, 8, 9Page 23


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Common Pilot Channel (CPICH) Common Pilot Channel (CPICH) Carries pre-defined sequence Fixed rate 30Ksps SF=256 Primary CPICH (P-CPICH)

Uses the fixed channel code -- Cch,256,0 Scrambled by the primary scrambling code Only one CPICH per cell Broadcast over the entire cell The P-CPICH is a phase reference for SCH, Primary CCPCH, AICH, PICH. By default, it is also a phase reference for downlink DPCHPre-defined symbol sequenceTslot = 2560 chips , 20 bits

Slot #0

Slot #1

Slot # i

Slot #14

1 radio frame: Tr = 10 ms


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Primary Common Control Physical Channel (P-CCPCH) Fixed rate, fixed OVSF code30kspsCch,256,1 Carry BCH transport channel The PCCPCH is not transmitted during the first 256 chips of each time slot Only data part STTD transmit diversity may be used256 chips SCH T

PCCPCH Data18 bits slot = 2560 chips,20 bits

Slot #0

Slot #1

Slot #i 1 radio frame: T f = 10 ms

Slot #14


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Paging Indicator Channel (PICH) PICH is a fixed-rate (SF=256) physical channel used to carry the Paging Indicators (PI). Frame structure of PICH: one frame of length 10ms consists of 300 bits of which 288 bits

are used to carry paging indicators and the remaining 12 bits are not defined N paging indicators {PI0, , PIN-1} in each PICH frame, N=18, 36, 72, or 144 If a paging indicator in a certain frame is set to 1, it indicates that UEs associated with

this paging indicator should read the corresponding frame of the associated S-CCPCH

288 bits for paging indicationb0 b1

12 bits (undefined)b 287 b 288 b 299

One radio frame (10 ms)


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Secondary Common Control Physical Channel (S-CCPCH) Carry FACH and PCH SF =256 - 4 Two kinds of S-CCPCH: with or without FACH and PCH can be mapped to the

TFCI. UTRAN decides if a TFCI should be transmitted, UE must support TFCI Possible rates are the same as that of

same or separate S-CCPCHs. If

mapped to the same S-CCPCH, theycan be mapped to the same fame

downlink DPCH

TFCI N TFCI bits

Data N Data bits T slot = 2560 chips, 20*2 k bits (k=0..6)

Pilot N Pilot bits

Slot #0

Slot #1

Slot #i 1 radio frame: T f = 10 ms

Slot #14


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Physical Random Access Channel (PRACH) The random-access transmission data consists of two parts:

One or several preambles: each preamble is of length 4096chips and consists of 256 repetitions of a signature whose length is 16 chips, 16 available signatures totally 10 or 20ms message part

Which signature is available and the length of message part are determined by higher layer

Preamble 4096 chips

Preamble

Preamble

Message part

10 ms (one radio frame) Message part 20 ms (two radio frames)

Preamble 4096 chips

Preamble

Preamble


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PRACH Access Timeslot Structureradio frame: 10 ms 5120 chips radio frame: 10 ms

#1

#2

#3

#4

#5

#6

#7

#8

#9

#10

#11

#12

#13

#14

Access slot #0Access slot #1

Random Access Transmission Random Access Transmission Random Access Transmission Random Access Transmission

Access slot #7 Access slot #8

Access slot #14


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PRACH Message StructureData N data bits

Data

Control

Pilot N Pilot bits T slot = 2560 chips, 10*2 k bits (k=0..3)

TFCI N TFCI bits

Slot # 0

Slot # 1

Slot # i

Slot # 14

Message part radio frame TRACH = 10 ms


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Acquisition Indicator Channel (AICH) Frame structure of AICHtwo frames, 20 ms, consists of a repeated sequence of

15 consecutive AS, each of length 40 symbols(5120 chips). Each time slot consists of two partsan Acquisition-Indicator(AI) and a part of duration 1024chips with no transmission Acquisition-Indicator AI have 16 kinds of Signature

P-CPICH is the phase reference of AICH

AI parta0 a1 a2 a30 a31 a32 a33

Unused parta38 a39

AS #14

AS #0

AS #1

AS #i 20 ms

AS #14

AS #0


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Uplink Dedicated Physical Channel (DPDCH&DPCCH) Uplink DPDCH and DPCCH are I/Q code division multiplexed (CDM)

within each radio frame Uplink DPDCH carries data generated at higher layer Uplink DPCCH carries control information generated at Layer 1 Each frame is 10ms and consists of 15 time slots, each time slot

consists of 2560 chips The spreading factor of uplink DPDCH is from 4 to 256 The spreading factor of uplink DPDCH and DPCCH can be different in

the same Layer 1 connection Each DPCCH time slot consists of Pilot, TFCIFBITPC


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Frame Structure of Uplink DPDCH/DPCCH

DPDCH

Data N databits

DPCCH

Pilot Npilot bits

TFCI NTFCI bitsk

FBI NFBI bits

TPC NTPC bits

Tslot = 2560 chips, 10*2 bits (k=0..6)

Slot #0 Slot #1

Slot #i 1 radio frame: Tf = 10 ms

Slot #14


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Downlink Dedicated Physical Channel (DPDCH+DPCCH) DPCH consists of dedicated data and control information Control information includesPilotTPCTFCI (optional) The spreading factor of DCH can be from 512 to 4,and can be

changed during connection Downlink DPDCH and DPCCH is time division multiplexing

(TDM)


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Frame Structure of Downlink DPCH (DPDCH+DPCCH)

DPDCH Data1 Ndata1 bits

DPCCH TPC NTPC bits TFCI NTFCI bits

DPDCH Data2 Ndata2 bits

DPCCH Pilot Npilot bits

Tslot = 2560 chips, 10*2 k bits (k=0..7)

Slot #0

Slot #1

Slot #i One radio frame, Tf = 10 ms

Slot #14


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High-Speed Physical Downlink Shared Channel (HS-PDSCH) Bear HSDPA traffic data and layer2 bits mapped from the transport

channel SF=16, can be configured several channels to increase data service

Data N Data 1 bits T slot = 2560 chips, M*10*2 k bits (k=4)

Slot #0

Slot#1 1 subframe: Tf = 2 ms

Slot #2


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High-Speed Shared Control Channel (HS-SCCH)

Carries physical layer signalling to a single UE ,such as modulation scheme (1

bit) ,channelization code set (7 bit), transport Block size (6bit),HARQ processnumber (3bit), redundancy version (3bit), new data indicator (1bit), UE identity (16bit)

HS-SCCH is a fixed rate (60 ksps, SF=128) downlink physical channel used to carry downlink signalling related to HS-DSCH transmission

Data N Data 1bits T slot = 2560 chips, 40 bits

Slot #0

Slot#1 1 subframe: T f = 2 ms

Slot #2


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High-Speed Dedicated Physical Control Channel (HS-DPCCH ) HS-DPCCH carries information to acknowledge downlink transport blocks and

feedback information to the system for scheduling and link adaptation of transport block CQI and ACK/NACK Physical Channel , Uplink , SF=256, power controlT slot = 2560 chips HARQ-ACK 2 Tslot = 5120 chips CQI

One HS-DPCCH subframe (2 ms)

Subframe #0

Subframe #i One radio frame Tf = 10 ms

Subframe #4


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Chapter 2 Physical Layer Key Technology Section 1 Physical Channel Structure and Functions Section 2 Channel Mapping


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Mapping Relation Between ChannelsLogical channels BCCH Transport channels BCH FACH PCCH CCCH PCH RACH FACH CTCH DCCH, DTCH FACH DCH HS-DSCH RACH, FACH Physical channels P-CCPCH S-CCPCH S-CCPCH PRACH S-CCPCH S-CCPCH DPDCH HS-PDSCH PRACH, S-CCPCH


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Synchronization ProcedureCell SearchSlot synchronizationUE uses PSC to acquire slot synchronization to a cell

Frame synchronization and code-group identification

UE uses SSC to find frame synchronization and identify the code group of the cell found in the first step

Scrambling-code identification

UE determines the primary scrambling code through correlation over the CPICH with all codes within the identified group, and then detects the P-CCPCH and reads BCH information


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Synchronization Procedure Channel Timing RelationshipPrimary SCH Secondary SCH Any CPICH

P - CCPCH, (SFN modulo 2) = 0 t CCPCH,k St PICH PICH for k:th S #0 #1 #2 #3 #4 #5 - CCPCH #6 #7 #8

P - CCPCH, (SFN modulo 2) = 1

k:th S - CCPCH

AICH access slo ts

#9

#10

#11

#12

#13

#14

t DPCH,n

n:th DPCH

10 ms


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Random Access ProcedureSTART Choose a RACH sub channel from available ones

Get available signatures

Set Preamble Retrans Max

Set Preamble_Initial_Power

Send a preamble

No AI Choose a access slot again Check the corresponding AI Get positive AI Choose a signature and increase preamble transmit power The counter of preamble retransmit Subtract-1, Commanded preamble power increased by Power Ramp Step Increase message part power by p -m based on preamble power Get negative AI

Send the corresponding message part

Y

Counter> 0 & Preamble powermaximum allowed power 0 then repeat from step 6. Otherwise exit the physical random access procedure


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Random Access ProcedureRACH 7. If a negative acquisition indicator corresponding to the selected signature is detected in the downlink access slot corresponding to the selected uplink access slot, exit the physical random access procedure Signature 8. If a positive acquisition indicator corresponding to the selected signature is detected , Transmit the random access message three or four uplink access slots after the uplink access slot of the last transmitted preamble 9. Exit the physical random access procedure


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Transmit diversity ModeApplication of Tx diversity modes on downlink physical channelPhysical channel type Open loop mode TSTD P-CCPCH SCH S-CCPCH DPCH PICH HS-PDSCH HS-SCCH AICH applied STTD applied applied applied applied applied applied applied Closed loop mode Mode 1 applied applied Mode 2 applied


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Transmit Diversity-STTD Space time block coding based transmit antenna diversity(STTD

4 consecutive bits b0, b1, b2, b3 using STTD coding

b0 b1 b2 b3

Antenna 1

b0 b1 b2 b3-b 2 b 3 b 0 -b 1 Antenna 2 Channel bits STTD encoded channel bits for antenna 1 and antenna 2.


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Transmit Diversity-TSTDTime switching transmit diversity (TSTD) is used only on SCH channel.

Slot #0

Slot #1

Slot #2

Slot #14

ac pAntenna 1

(Tx OFF)

acp acsi,2

ac p aci,14 s

ac s

i,0

(Tx OFF)

(Tx OFF)

acpi,1 acs

(Tx OFF)

(Tx OFF)

Antenna 2(Tx OFF)(Tx OFF) (Tx OFF)


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Summary

This course mainly introduces the basic concept,

key technology and procedures of WCDMA physical layer This is very helpful for comprehension of Uu

interface features and further study


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Thank Youwww.huawei.com

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WCDMA Radio Interface Physical Layer (With Comment) ISSUE 1.0