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Page 1: WCDMA Radio Interface and Physical Layer

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Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.

WCDMA Radio Interface Physical Layer

Page 2: WCDMA Radio Interface and Physical Layer

Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved. Page1

Foreword

The physical layer offers data transport services to higher

layers.

The physical layer is expected to perform the following

functions in order to provide the data transport service, for

example: spreading, modulation and demodulation,

despreading, Inner-loop power control and etc.

Page 3: WCDMA Radio Interface and Physical Layer

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Objectives

Upon completion of this course, you will be able to:

Outline radio interface protocol Architecture

Describe structure and functions of different physical

channels

Describe UMTS physical layer procedures

Page 4: WCDMA Radio Interface and Physical Layer

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Contents

1. Physical Layer Overview

2. Physical Channels

3. Physical Layer Procedure

Page 5: WCDMA Radio Interface and Physical Layer

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Contents

1. Physical Layer Overview

2. Physical Channels

3. Physical Layer Procedure

Page 6: WCDMA Radio Interface and Physical Layer

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UTRAN Network Structure

RNS

RNC

RNS

RNC

Core Network

NodeB NodeB NodeB NodeB

Iu-CS Iu-PS

Iur

Iub Iub Iub Iub

CN

UTRAN

UE Uu

CS PS

Iu-CS Iu-PS

CS PS

Page 7: WCDMA Radio Interface and Physical Layer

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Uu Interface Protocol Structure

L3

co

ntr

ol

co

ntr

ol

co

ntr

ol

co

ntr

ol

C-plane signaling U-plane information

PHY

L2/MAC

L1

RLC

DC Nt GC

L2/RLC

MAC

RLC RLC

RLC

Duplication avoidance

UuS boundary

L2/BMC

control

PDCP PDCP L2/PDCP

DC Nt GC

RRC

RLC RLC

RLC RLC

BMC

radio bearer

logical channel

transport channel

Page 8: WCDMA Radio Interface and Physical Layer

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RAB, RB and RL

RAB

RB

RL NodeB

RNC CN UE

UTRAN

Page 9: WCDMA Radio Interface and Physical Layer

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Contents

1. Physical Layer Overview

2. Physical Channels

3. Physical Layer Procedure

Page 10: WCDMA Radio Interface and Physical Layer

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Contents

2. Physical Channels

2.1 Physical Channel Structure and Functions

2.2 Channel Mapping

Page 11: WCDMA Radio Interface and Physical Layer

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WCDMA Radio Interface Channel Definition

Logical Channel = information container

Defined by <What type of information> is transferred

Transport Channel = characteristics of transmission

Described by <How> and with <What characteristics> data

is transmitted over the radio interface

Physical Channel = specification of the information global

content

providing the real transmission resource, maybe a

frequency , a specific set of codes and phase

Page 12: WCDMA Radio Interface and Physical Layer

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Logical Channel

Control channel

Traffic channel

Dedicated traffic channel (DTCH)

Common traffic channel (CTCH)

Broadcast control channel (BCCH)

Paging control channel (PCCH)

Dedicate control channel (DCCH)

Common control channel (CCCH)

Page 13: WCDMA Radio Interface and Physical Layer

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Transport Channel

Dedicated Channel (DCH)

Broadcast channel (BCH)

Forward access channel

(FACH)

Paging channel (PCH)

Random access channel (RACH)

High-speed downlink shared

channel

(HS-DSCH)

Common transport

channel

Dedicated transport

channel

Page 14: WCDMA Radio Interface and Physical Layer

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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

Page 15: WCDMA Radio Interface and Physical Layer

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Downlink Physical Channel

Downlink Dedicated Physical Channel (DL DPCH)

Downlink Common Physical Channel

Primary Common Control Physical Channel (P-CCPCH)

Secondary Common Control Physical Channel (S-CCPCH)

Synchronization Channel (SCH)

Paging Indicator Channel (PICH)

Acquisition Indicator Channel (AICH)

Common Pilot Channel (CPICH)

High-Speed Physical Downlink Shared Channel (HS-PDSCH)

High-Speed Shared Control Channel (HS-SCCH)

Page 16: WCDMA Radio Interface and Physical Layer

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Uplink Physical Channel

Uplink Dedicated Physical Channel

Uplink Dedicated Physical Data Channel (Uplink DPDCH)

Uplink Dedicated Physical Control Channel (Uplink DPCCH)

High-Speed Dedicated Physical Channel (HS-DPCCH)

Uplink Common Physical Channel

Physical Random Access Channel (PRACH)

Page 17: WCDMA Radio Interface and Physical Layer

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Function of Physical Channel

NodeB

UE

P-CCPCH-Primary Common Control Physical Channel

P-CPICH--Primary Common Pilot Channel

SCH--Synchronisation Channel

Cell Search Channels

DPDCH--Dedicated Physical Data Channel

DPCCH--Dedicated Physical Control Channel

Dedicated Channels

Paging Channels

PICH--Paging Indicator Channel

SCCPCH--Secondary Common Control Physical

Channel

PRACH--Physical Random Access Channel

AICH--Acquisition Indicator Channel

Random Access Channels

HS-DPCCH--High Speed Dedicated Physical Control

Channel

HS-SCCH--High Speed Share Control Channel HS-PDSCH--High Speed Physical Downlink Share

Channel

High Speed Downlink Share Channels

Page 18: WCDMA Radio Interface and Physical Layer

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Synchronization Channels (P-SCH & S-SCH) Used for cell search

Two sub channels: P-SCH and S-SCH

SCH is transmitted at the first 256

chips of every time slot

Primary synchronization code is

transmitted repeatedly in each time

slot

Secondary synchronization code

specifies the scrambling code groups

of the cell

Primary

SCH

Secondary

SCH

Slot #0 Slot #1 Slot #14

ac s i,0

p ac p ac p ac

ac s i,1 ac s

i,14

256 chips

2560 chips

One 10 ms SCH radio frame

Page 19: WCDMA Radio Interface and Physical Layer

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Secondary Synchronization Channel (S-SCH)

slot number Scrambling Code Group #0 #1 #2 #3 #4 #5 #6 #7 #8 #9 #10 #11 #12 #13 #14

Group 0 1 1 2 8 9 10 15 8 10 16 2 7 15 7 16

Group 1 1 1 5 16 7 3 14 16 3 10 5 12 14 12 10

Group 2 1 2 1 15 5 5 12 16 6 11 2 16 11 15 12

Group 3 1 2 3 1 8 6 5 2 5 8 4 4 6 3 7

Group 4 1 2 16 6 6 11 15 5 12 1 15 12 16 11 2

Group 61 9 10 13 10 11 15 15 9 16 12 14 13 16 14 11

Group 62 9 11 12 15 12 9 13 13 11 14 10 16 15 14 16

Group 63 9 12 10 15 13 14 9 14 15 11 11 13 12 16 10

…….. acp

Slot # ?

P-SCH acp

Slot #?

16 6 S-SCH

acp

Slot #?

11 Group 2

Slot 7, 8, 9 256 chips

Page 20: WCDMA Radio Interface and Physical Layer

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Primary Common Pilot Channel (PCPICH)

Primary CPICH

Carrying pre-defined sequence

Fixed channel code: Cch, 256, 0, Fixed rate 30Kbps

Scrambled by the primary scrambling code

Broadcast over the entire cell

A phase reference for SCH, Primary CCPCH, AICH, PICH and

downlink DPCH, Only one PCPICH per cell

Pre-defined symbol sequence

Slot #0 Slot #1 Slot # i Slot #14

Tslot = 2560 chips , 20 bits

1 radio frame: Tr = 10 ms

Page 21: WCDMA Radio Interface and Physical Layer

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Primary Common Control Physical Channel (PCCPCH)

Carrying BCH transport channel

Fixed rate, fixed OVSF code (30kbps,Cch, 256, 1)

The PCCPCH is not transmitted during the first 256 chips of

each time slot

PCCPCH Data

18 bits

Slot #0

1 radio frame: T f = 10 ms

Slot #1 Slot #i

256 chips

Slot #14

T slot

= 2560 chips,20 bits

SCH

Page 22: WCDMA Radio Interface and Physical Layer

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Paging Indicator Channel (PICH)

Carrying Paging Indicators (PI)

Fixed rate (30kbps), SF = 256

N paging indicators {PI0, …, PIN-1} in each PICH frame, N=18, 36,

72, or 144

One radio frame (10 ms)

b 1 b 0

288 bits for paging indication 12 bits (undefined)

b 287 b 288 b 299

Page 23: WCDMA Radio Interface and Physical Layer

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Secondary Common Control Physical Channel (SCCPCH)

Carrying FACH and PCH, SF = 256 - 4

Pilot: used for demodulation

TFCI: Transport Format Combination Indication, used for describe

data format

Data

N bits

Slot #0 Slot #1 Slot #i Slot #14

1 radio frame: T f = 10 ms

T slot = 2560 chips,

Data

Pilot

N bits Pilot N bits TFCI

TFCI

20*2 k bits (k=0..6)

Page 24: WCDMA Radio Interface and Physical Layer

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Physical Random Access Channel (PRACH)

Carrying uplink signaling and data, consist of two parts:

One or several preambles: 16 kinds of available preambles

10 or 20ms message part

Message part Preamble

4096 chips 10 ms (one radio frame)

Preamble Preamble

Message part Preamble

4096 chips 20 ms (two radio frames)

Preamble Preamble

Page 25: WCDMA Radio Interface and Physical Layer

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PRACH Message Structure

Pilot

N bits

Slot # 0 Slot # 1 Slot # i Slot # 14

Message part radio frame T = 10 ms

T slot = 2560 chips, 10*2

Pilot

TFCI

N bits TFCI

Data

N data

bits Data

Control

k bits (k=0..3)

Page 26: WCDMA Radio Interface and Physical Layer

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PRACH Access Timeslot Structure

#1 #2 #3 #4 #5 #6 #7 #8 #9 #10 #11 #12 #13 #14

5120 chips

radio frame: 10 ms radio frame: 10 ms

Access slot #0 Random Access Transmission

Access slot #1

Access slot #7

Access slot #14

Random Access Transmission

Random Access Transmission

Random Access Transmission Access slot #8

Page 27: WCDMA Radio Interface and Physical Layer

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Acquisition Indicator Channel (AICH)

Carrying the Acquisition Indicators (AI), SF = 256

There are 16 kinds of Signature to generate AI

AS #14 AS #0 AS #1 AS #i AS #14 AS #0

a1 a2 a0 a31 a32 a30 a33 a38 a39

AI part Unused part

20 ms

Page 28: WCDMA Radio Interface and Physical Layer

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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

DPDCH carries data generated at Layer 2 and higher layer,

the OVSF code is Cch,SF,SF/4, where SF is from 256 to 4

DPCCH carries control information generated at Layer 1,

the OVSF code is Cch,256,0

Page 29: WCDMA Radio Interface and Physical Layer

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Uplink Dedicated Physical Channel (DPDCH&DPCCH)

Frame Structure of Uplink DPDCH/DPCCH

Pilot Npilot bits

TPC NTPC bits

Data Ndata bits

Slot #0 Slot #1 Slot #i Slot #14

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

1 radio frame: Tf = 10 ms

DPDCH

DPCCH FBI

NFBI bits TFCI

NTFCI bits

Page 30: WCDMA Radio Interface and Physical Layer

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Downlink Dedicated Physical Channel (DPDCH+DPCCH)

Downlink DPDCH and DPCCH is time division multiplexing

(TDM).

DPDCH carries data generated at Layer 2 and higher layer

DPCCH carries control information generated at Layer 1

SF of downlink DPCH is from 512 to 4

Page 31: WCDMA Radio Interface and Physical Layer

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Downlink Dedicated Physical Channel (DPDCH+DPCCH)

Frame Structure of Downlink DPCH (DPDCH+DPCCH)

One radio frame, Tf = 10 ms

Slot #0 Slot #1 Slot #i Slot #14

Tslot = 2560 chips, 20*2k bits (k=-1..6)

Data2

Ndata2 bits

DPDCH

TFCI

NTFCI bits

Pilot

Npilot bits

Data1

Ndata1 bits

DPDCH DPCCH DPCCH

TPC

NTPC bits

Page 32: WCDMA Radio Interface and Physical Layer

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High-Speed Physical Downlink Shared Channel (HS-PDSCH) Bearing service data and layer 2 overhead bits mapped from

the transport channel

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

service

Slot #0 Slot#1 Slot #2

Tslot = 2560 chips, M*10*2k bits (k=4)

Data Ndata1 bits

1 subframe: Tf = 2 ms

Page 33: WCDMA Radio Interface and Physical Layer

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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 process number (3bit), redundancy version (3bit), new

data indicator (1bit), UE identity (16bit)

HS-SCCH is a fixed rate (60 kbps, SF=128) downlink physical channel

used to carry downlink signalling related to HS-DSCH transmission

Slot #0 Slot#1 Slot #2

Tslot = 2560 chips, 40 bits

Data Ndata1 bits

1 subframe: Tf = 2 ms

Page 34: WCDMA Radio Interface and Physical Layer

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High-Speed Dedicated Physical Control Channel (HS-DPCCH )

Carrying 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

Subframe #0 Subframe #i Subframe #n

One HS-DPCCH subframe ( 2ms )

ACK/NACK

1 radio frame: Tf = 10 ms

CQI

Tslot = 2560 chips 2 Tslot = 5120 chips

Page 35: WCDMA Radio Interface and Physical Layer

Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved. Page42

Contents

2. Physical Channels

2.1 Physical Channel Structure and Functions

2.2 Channel Mapping

Page 36: WCDMA Radio Interface and Physical Layer

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Mapping Between Channels Logical channels Transport channels Physical channels

BCCH BCH P-CCPCH

FACH S-CCPCH

PCCH PCH S-CCPCH

CCCH RACH PRACH

FACH S-CCPCH

CTCH FACH S-CCPCH

DCCH, DTCH DCH DPDCH

HS-DSCH HS-PDSCH

RACH, FACH PRACH, S-CCPCH

Page 37: WCDMA Radio Interface and Physical Layer

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Contents

1. Physical Layer Overview

2. Physical Channels

3. Physical Layer Procedure

Page 38: WCDMA Radio Interface and Physical Layer

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Synchronization Procedure - Cell Search

Frame synchronization &

Code Group Identification

Scrambling Code

Identification

UE uses SSC to find frame

synchronization and identify the code

group of the cell found in the first

step

UE determines the primary scrambling

code through correlation over the

PCPICH with all codes within the

identified group, and then detects the

P-CCPCH and reads BCH information。

Slot

Synchronization

UE uses PSC to acquire slot

synchronization to a cell

Page 39: WCDMA Radio Interface and Physical Layer

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Random Access

Procedure

START

Choose a RACH sub channel from

available ones

Get available signatures

Set Preamble Retrans Max

Set Preamble_Initial_Power

Send a preamble

Check the corresponding AI

Increase message part power by

p-m based on preamble power

Set physical status to be RACH

message transmitted Set physical status to be Nack

on AICH received

Choose a access slot again

Counter> 0 & Preamble power

< maximum allowed power

Choose a signature and increase preamble transmit power

Set physical status to be Nack

on AICH received

Get negative AI

No AI

Report the physical status to MAC

END

Get positive AI

The counter of preamble retransmit

Subtract 1, Commanded preamble power

increased by Power Ramp Step

N

Y

Send the corresponding message part

Page 40: WCDMA Radio Interface and Physical Layer

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Transmit Diversity Mode

Application of Tx diversity modes on downlink physical

channel Physical channel type Open loop mode Closed loop mode

TSTD STTD Mode 1 Mode 2

P-CCPCH – applied – –

SCH applied – – –

S-CCPCH – applied – –

DPCH – applied applied applied

PICH – applied – –

HS-PDSCH – applied applied –

HS-SCCH – applied – –

AICH – applied – –

Page 41: WCDMA Radio Interface and Physical Layer

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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

Antenna 2 Channel bits

STTD encoded channel bits

for antenna 1 and antenna 2.

b0 b1 b2 b3

-b2 b3 b0 -b1

Page 42: WCDMA Radio Interface and Physical Layer

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Transmit Diversity - TSTD

Time switching transmit diversity (TSTD) is used only on

SCH channel

Antenna 1

Antenna 2

i,0

i,1

acs i,14

Slot #0 Slot #1 Slot #14

i,2

acp

Slot #2

(Tx

OFF) (Tx

OFF)

(Tx

OFF)

(Tx

OFF)

(Tx

OFF) (Tx

OFF)

(Tx

OFF)

acp acp

acs acs

acp

acs (Tx

OFF)

Page 43: WCDMA Radio Interface and Physical Layer

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Closed Loop Mode

Used in DPCH and HS-PDSCH

Page 44: WCDMA Radio Interface and Physical Layer

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References

TS 25.104 UTRA (BS) FDD Radio Transmission and Reception

TS 25.201 Physical layer-general description

TS 25.211 Physical channels and mapping of transport channels onto physical

channels (FDD)

TS 25.212 Multiplexing and channel coding (FDD)

TS 25.213 Spreading and modulation (FDD)

TS 25.214 Physical layer procedures (FDD)

TS 25.308 UTRA High Speed Downlink Packet Access (HSDPA)

TR 25.877 High Speed Downlink Packet Access (HSDPA) - Iub/Iur Protocol

Aspects

TR 25.858 Physical layer aspects of UTRA High Speed Downlink Packet Access

Page 45: WCDMA Radio Interface and Physical Layer

Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved. Page55

This course mainly introduces the basic concept, key

technology and procedures of WCDMA physical layer.

These knowledge is very important for understanding Uu

interface and further study.

Summary

Page 46: WCDMA Radio Interface and Physical Layer

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