2 UMTS Radio Interface Physical Layer

8/3/2019 2 UMTS Radio Interface Physical Layer

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Huawei Confidential. All Rights Reserved

UMTS Radio Interface Physical Layer

ISSUE 1.0


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Internal Use2

Physical layer offers data transport services

to higher layers.

The access to these services is through the

use of transport channels via the MAC sub-

layer.


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Internal Use3

ReferencesReferences

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); Overall description; Stage 2

TR 25.877 High Speed Downlink Packet Acces

(HSDPA) - Iub/IurProtocol Aspects

TR 25.858 Physical layer aspects of UTRA High

Speed Downlink Packet Access


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ObjectiveObjective

Upon completion this course, you will be

able to:

Understand radio interface protocolArchitecture

Understand key technology of UMTS

physical layer

Understand UMTS physical layer

procedures


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Internal Use5

Chapter 1 : Physical Layer OverviewChapter 1 : Physical Layer Overview

Chapter 2 : Physical Layer Key TechnologyChapter 2 : Physical Layer Key Technology

Chapter 3 : Physical Layer ProceduresChapter 3 : Physical Layer Procedures

Chapter 4 : Transmit Diversity on PhysicalChapter 4 : Transmit Diversity on PhysicalChannelChannel


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UTRAN Protocol StructureUTRAN Protocol StructureUTRAN Protocol StructureUTRAN Protocol Structure

RNS

RNC

RNS

RNC

Core Network

Node B Node B Node B Node B

Iu Iu

Iur

Iub IubIub Iub


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Internal Use7

Radio Interface Protocol StructureRadio Interface Protocol StructureRadio Interface Protocol StructureRadio Interface Protocol Structure

L3

con

trol

con

trol

con

trol

con

trol

Logical

Channels

Transport

Channels

C-plane signalling U-plane information

PHY

L2/MAC

L1

RLC

DCNtGC

L2/RLC

MAC

RLCRLC

RLC

RLC

RLCRLC

RLC

Duplication avoidance

UuS boundary

BMCL2/BMC

control

PDCPPDCP L2/PDCP

DCNtGC

Radio

Bea

rers

RRC


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Internal Use8

Data Processing at Physical LayerData Processing at Physical LayerData Processing at Physical LayerData Processing at Physical Layer

Data from MAC

LayerTB

Channel coding

and multiplexing

Spreading and

modulation


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Internal Use9

Spreading TechnologySpreading TechnologySpreading TechnologySpreading Technology

Spreading consists of 2 steps

Channelization operation: 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

through multiplication with OVSF code.

Scrambling operation is applied to the spreading signal.

Data bit

OVSF

code

Scrambling

code

Chips after

spreading


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Internal Use10

Channelization CodeChannelization CodeChannelization CodeChannelization 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 e ke SF-1.

SF = 1 SF = 2 SF = 4

Cch,1,0 = (1)

Cch,2,0 = (1,1)

Cch,2,1 = (1,-1)

Cch,4,0 =(1,1,1,1)

Cch,4,1 = (1,1,-1,-1)

Cch,4,2 = (1,-1,1,-1)

Cch,4,3 = (1,-1,-1,1)


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Scrambling codeGOLD sequence.

Scrambling code period : 10ms ,or 38400 chips. The code used for scrambling of uplink DPCCH/DPDCH may be of either

long or short type, There are 224

long and 224

short uplink scrambling

codes. Uplink scrambling codes are assigned by higher layers.

For downlink physical channels, a total of 218

-1 = 262,143 scrambling

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

used.

Scrambling CodeScrambling CodeScrambling CodeScrambling Code


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Internal Use13

Group 0

Group1

Group 63

512 primary

scrambling codes

64 primary scrambling

code groupsEach group consists of8

primary scrambling codes

Primary Scrambling Code GroupPrimary Scrambling Code GroupPrimary Scrambling Code GroupPrimary Scrambling Code Group

Primary

scramblingcodes for

downlink

physical

channels

Primary

scrambling code 0

Primaryscrambling code 1

Primaryscrambling code 7

Primaryscrambling code

8*63

Primaryscrambling code

63*87


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Section 1 Physical Channel Structure and Function

Section 2 Channel Mapping


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Traffic channel

Control channel

Logical channelLogical channelLogical channelLogical 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


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Broadcast channel (BCH)

Forward access channel (FACH)

Paging channel (PCH)

Random access channel (RACH)

BCH, FACH & PCH are downlink channels.

Only RACH is common uplink channel

Dedicated Channel (DCH)

Dedicated Channel (DCH) exists on uplink

or downlink channel.

Common transport

channel

Dedicated transport

channel

Transport channelTransport channelTransport channelTransport channel


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Internal Use19

Physical ChannelPhysical ChannelPhysical ChannelPhysical 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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Internal Use20

Downlink Physical ChannelDownlink Physical ChannelDownlink Physical ChannelDownlink Physical Channel

Downlink Common Physical Channel

Common Pilot Channel (CPICH)

Synchronization Channel (SCH)

Common Control Physical Channel (CCPCH)

Paging Indicator Channel (PICH)

Acquisition Indicator Channel (AICH)

Downlink Dedicated Physical Channel

Downlink DPCH

Downlink

Physical

Channel


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Downlink Dedicated Physical Channel (DPCH)Downlink Dedicated Physical Channel (DPCH)Downlink Dedicated Physical Channel (DPCH)Downlink Dedicated Physical Channel (DPCH)

DCH consists of dedicated data and control information.

Control information includesPilot, TPC, TFCI (optional).

SF of DCH : 512 - 4,and can be changed during connection

DPDCH and DPCCH are time multiplexed.

Multi-code transmission within one CCTrCH uses the samespreading factor. In this case, the DPCH control information is

transmitted only on the first downlink DPCH.

Different CCTrCH can use different spreading factors in the

case there are several CCTrCHs for one UE. In this case

information of only one DPCCH needs to be transmitted.

Note:

CCTrCH : Coded Composite Transport Channel


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Internal Use22

Frame Structure ofDownlink DPCHFrame Structure ofDownlink DPCHFrame Structure ofDownlink DPCHFrame Structure ofDownlink DPCH

One radio frame, Tf= 10 ms

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

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

Data2

Ndata2 bits

DPDCH

TFCI

NTFCI bits

Pilot

Npilot bitsData1

Ndata1 bits

DPDCH DPCCH DPCCH

TPC

NTPC bits


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Internal Use23

Functions ofDownlink DPDCH/DPCCHFunctions ofDownlink DPDCH/DPCCH

DCH dataDPDCH

DPCCH

Provide control data for DPDCH ,such

as demodulation, power control,etc.

Data bearerData bearer

at physical layerat physical layer

DCH

data


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Internal Use24

Common Pilot Channel(CPICH)Common Pilot Channel(CPICH)Common Pilot Channel(CPICH)Common Pilot Channel(CPICH)

Common Pilot Channel (CPICH)

Carries pre-defined sequence.

Fixed rate 30Kbps SF=256

Can use STTD on this channel


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Internal Use25

Common Pilot Channel (CPICH)Common Pilot Channel (CPICH)Common Pilot Channel (CPICH)Common Pilot Channel (CPICH)

Primary CPICH

Uses OVSF 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 DPCH.

Secondary CPICH An arbitrary channel code of SF=256 is used for S-CPICH S-CPICH is scrambled by either the primary or a secondary scrambling

code There may be zero, one , or several secondary CPICH.

S-CPICH may be transmitted over part of the cell S-CPICH may be a phase reference for S-CCPCH and downlink DPCH.


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Synchronization Channel (SCH)Synchronization Channel (SCH)Synchronization Channel (SCH)Synchronization Channel (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.

PSC is transmitted repeatedly in

each time slot.

SSC specifies the scrambling

code groups of the cell. SSC is chosen from a set of 16

different codes of length 256,

there are altogether64 primary

scrambling code groups.

PrimarySCH

SecondarySCH

256 chips

2560 chips

One 10 ms SCH radio frame

acs,

acp

acs,

acp

acs,

acp

Slot #0 Slot #1 Slot #14


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Internal Use27

Fixed rate30kbpsSF=256, 1

Carry BCH transport channel Not transmitted during the first 256 chips of each time slot.

Only data part

STTD transmit diversity may be used

Data18 bits


Tslot = 2560 chips , 20 bits

1 radio frame: Tf = 10 ms

(Tx OFF)

256 chips

Primary Common Control Physical Channel (PCCPCH)Primary Common Control Physical Channel (PCCPCH)Primary Common Control Physical Channel (PCCPCH)Primary Common Control Physical Channel (PCCPCH)


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Secondary Common Control Physical Channel (SCCPCH)Secondary Common Control Physical Channel (SCCPCH)Secondary Common Control Physical Channel (SCCPCH)Secondary Common Control Physical Channel (SCCPCH)

Carry FACH and PCH.

Two types of SCCPCH:with or without TFCI. UTRAN

decides if a TFCI should be

transmitted, UE must support

TFCI.

Possible rates are the same as

that of downlink DPCH

SF =256 - 4.

FACH and PCH can be mapped tothe same or separate SCCPCHs.

If mapped to the same S-CCPCH,

they can be mapped to the same

frame.


Tslot = 2560 chips, 20*2k bits (k=0..6)

PilotNpilot bits

DataNdata bits


TFCINTFCI bits


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Internal Use29

Paging Indicator Channel (PICH)Paging Indicator Channel (PICH)Paging Indicator Channel (PICH)Paging Indicator Channel (PICH)

One radio frame (10 ms)

b1b0

288 bits for paging indication 12 bits (undefined)

b287 b288 b299

Fixed-rate (SF=256, 3), used to carry the Paging Indicators (PI).

PICH is always associated with an S-CCPCH to which a PCH transportchannel is mapped to.

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.


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Internal Use30

Acquisition Indicator Channel (AICH)Acquisition Indicator Channel (AICH)Acquisition Indicator Channel (AICH)Acquisition Indicator Channel (AICH)

Frame structure of AICHtwo frames, 20 ms consists of a repeated

sequence of 15 consecutive AS, each of length 20 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.

CPICH is the phase reference of AICH.

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

a1 a2a0 a31 a32a30 a33 a38 a39

AI part Unused part

20 ms


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Internal Use31

Uplink Physical ChannelUplink Physical ChannelUplink Physical ChannelUplink Physical Channel

Uplink Common Physical Channel

Physical Random Access Channel (PRACH)

Uplink Dedicated Physical Channel

Uplink Dedicated Physical Data Channel

(Uplink DPDCH)

Uplink Dedicated Physical Control Channel

(Uplink DPCCH) UplinkPhysical

Channel


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Uplink Dedicated Physical ChannelUplink Dedicated Physical ChannelUplink Dedicated Physical ChannelUplink Dedicated Physical Channel

DPDCH and DPCCH are code multiplexed within each radio frame

DPDCH carries data generated at Layer 2 and higher layer

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 SF of DPDCH : 4 256

SF of DPCCH : 256 fixed

Each DPCCH time slot consists of Pilot, TFCI, FBI, TPC


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Frame Structure of Uplink DPDCH/DPCCHFrame Structure of Uplink DPDCH/DPCCHFrame Structure of Uplink DPDCH/DPCCHFrame Structure of Uplink DPDCH/DPCCH

Pilot

Npilot bits

TPCNTPC bits

Data

Ndata bits




DPDCH

DPCCHFBI

NFBI bitsTFCI

NTFCI bits


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Internal Use34

Functions of Uplink DPDCH/DPCCHFunctions of Uplink DPDCH/DPCCHFunctions of Uplink DPDCH/DPCCHFunctions of Uplink DPDCH/DPCCH

DCH Data

DPDCH

DPCCH

Provide control data for DPDCH, such

as demodulation, power control, etc

Data bearerData bearerat physical layerat physical layer


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Physical Random Access Channel (PRACH)Physical Random Access Channel (PRACH)Physical Random Access Channel (PRACH)Physical Random Access Channel (PRACH)

The PRACH consist of 2 parts: Preamble

>one or several preamble.

>Each preamble is of length 4096chips and consists of 256

repetitions of a signature whose length is 16 chips. Total of

16 signatures>SF : 256

Message part :

>Two type, 10 or 20ms message part

>SF : 256 - 32

Which signature is available and the length of message part are

determined by higher layer


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PRACH Transmission StructurePRACH Transmission StructurePRACH Transmission StructurePRACH Transmission Structure

Message partPreamble

4096 chips10 ms (one radio frame)

Preamble Preamble

Message partPreamble

4096 chips 20 ms (two radio frames)

Preamble Preamble


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Internal Use37

Pilot

Npilot bits

DataNdata bits



Message part radio frame TRACH = 10 ms

Data

ControlTFCI

NTFCI bits

PRACH Message StructurePRACH Message StructurePRACH Message StructurePRACH Message Structure


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PRACH Access Timeslot StructurePRACH Access Timeslot StructurePRACH Access Timeslot StructurePRACH Access Timeslot Structure

#0 #1 #2 #3 #4 #5 #6 #7 #8 #9 #10 #11 #12 #13 #14

5120 chips

radio frame: 10 ms r adio frame: 10 ms

Acc

ess slot #0 Ra

ndom Acc

ess Tra

nsmission

Access slot #1

Access slot #7

Access slot #14

Random Access Transmission

Random Access Transmission

Random Access TransmissionAccess slot #8


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Internal Use39

Function of physical channelFunction of physical channel

Node B UE

P-CCPCH-Primary common control physical channel

SCH- Synchronisation Channel

P-CPICH-Primary common pilot channel

S-CPICH-secondary common pilot channel

Cell broadcast channels

DPDCH-dedicated physical data channel

DPCCH-dedicated physical control channel

Dedicated channels

Paging channels

PICH-paging IndicatorChannel

S-CCPCH-Secondary common control physical channel

PRACH-Physical random access channel

AICH-Acquisition Indicator Channel

Random access channels


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Internal Use40


Section 1 Physical Channel Structure and Function

Section 2 Channel Mapping


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Internal Use41

{XOR}

Transport

Channels(L1 Characteristics

Dependent)PCH BCH FACH RACH DCH

S-CCPCHP-CCPCHPhysical

ChannelsPRACH DPDCH

LogicalChannels

(DataDependent)

PCCH

DCCH

DTCH

DecicatedLogicalChannel

CipherOn

BCCH CCCH CTCH

HigherLayer data

Paging SystemInfoSignaling

CellBroadcast

Service

Signalingand

User data

DTCHDTCH

Channel MappingChannel MappingChannel MappingChannel Mapping


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Chapter 3 : Physical Layer ProcedureChapter 3 : Physical Layer Procedure

Section 1 Synchronisation Procedure ( Cell SearcSection 1 Synchronisation Procedure ( Cell Searc

Section 2 Random Access ProcedureSection 2 Random Access Procedure


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1. Synchronization Procedure1. Synchronization ProcedureCell SearchCell Search1. Synchronization Procedure1. Synchronization ProcedureCell SearchCell Search

Slot synchronization

Frame synchronization and

code-group identification

Scrambling-code

identification

UE uses PSC to acquire slot

synchronization to a cell

UE uses SSC to find frame

synchronization and identify

the code group of the cell

found in the first step

UE determines the primary scramblingcode 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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Internal Use45

1. Synchronization Procedure1. Synchronization Procedure Channel Timing RelationshipChannel Timing Relationship1. Synchronization Procedure1. Synchronization Procedure Channel Timing RelationshipChannel Timing Relationship

AICH accessslots

SecondarySCH

Primary

SCH

XS-CCPCH,k

10 ms

XPICH

#0 #1 #2 #3 #14#13#12#11#10#9#8#7#6#5#4

P-CCPCH, (SFN modulo 2) = 0 P-CCPCH, (SFN modulo 2) = 1

Any CPICH

k:th S-CCPCH

PICH for k:th S-CCPCH

n:th DPCHXDPCH,n

AnyPDSCH


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Chapter 3 : Physical Layer ProcedureChapter 3 : Physical Layer Procedure

Section 1 Synchronisation Procedure ( Cell SearcSection 1 Synchronisation Procedure ( Cell Searc

Section 2 Random Access ProcedureSection 2 Random Access Procedure


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2. Random access procedure2. Random access procedure -- RACHRACH2. Random access procedure2. Random access procedure -- RACHRACH


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2. Random Access Procedure2. Random Access ProcedureRACHRACH2. Random Access Procedure2. Random Access ProcedureRACHRACH

Physical random access procedure

1. UE decoded BCH to find out the available RACH sub-channel, its

scrambling code and available signature.

2. Randomly select one of the RACH sub-channels from the group its

access class allows to use. Signature also selected randomly from

among the available signatures.

3. Set Preamble Retransmission Counter to Preamble_ Retrans_ Max

4. Set Preamble Initial Power

5. Transmit a preamble using the selected uplink access slot, signature,

and preamble transmission power


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2. Random Access Procedure2. Random Access ProcedureRACHRACH2. Random Access Procedure2. Random Access ProcedureRACHRACH

7. If 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

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 lasttransmitted preamble

9. Exit physical random access procedure


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Internal Use51






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Internal Use53

Transmit DiversityTransmit Diversity--STTDSTTDTransmit DiversityTransmit Diversity--STTDSTTD

Space time block coding based transmit antenna diversity(STTD

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

b0 b1 b2 b3

b0 b1 b2 b3

-b2 b3 b0 -b1

Antenna 1

Antenna 2

Channel bits

STTD encoded channel bits

forantenna 1 and antenna 2.


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Transmit DiversityTransmit Diversity--TSTDTSTDTransmit DiversityTransmit Diversity--TSTDTSTD

Time switching transmit diversity (TSTD) is used only on SCH channel.

Antenna 1

Antenna 2

acsi,0

acp

acs,

acp

acsi,14

acp

Slot #0 Slot #1 Slot #14

acsi,2

acp

Slot #2

(Tx OFF)

(Tx OFF)

(Tx OFF)

(Tx OFF)

(Tx OFF)

(Tx OFF)

(Tx OFF)

(Tx OFF)

CCCC


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Transmit DiversityTransmit DiversityClosed Loop ModeClosed Loop ModeTransmit DiversityTransmit DiversityClosed Loop ModeClosed Loop Mode

Closed loop mode transmit diversity

Used in dedicated channel, DPCH and PDSCH, to improvedownlink performance based on feedback information from UE.

Base station transmits user information using 2 antennas. UE will

send feedback bits (FB) in uplink DPCCH, for NodeB to adjust the

phase of antenna 2 (as antenna 1 taken as reference), so as tomaximize the power received by UE.

In mode 1:

>Uses phase adjustment.

>Dedicated pilot symbols of 2 antennas different.

In mode 2:

>Phase and amplitude are adjusted.

>Dedicated pilot symbols of two antennas are the same.


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2 UMTS Radio Interface Physical Layer

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