02-WCDMA Radio Interface Physical Layer (1)

7/22/2019 02-WCDMA Radio Interface Physical Layer (1)

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HUAWEI TECHNOLOGIES CO., LTD. All rights reserved

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Internal

WCDMA Radio Interface

Physical Layer

ISSUE 1.0


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HUAWEI TECHNOLOGIES CO., LTD. All rights reserved Page 2

The physical layer offers data transport services to

higher layers (MAC sub-layer)

The access to these services is through the use of

transport channelsvia the MAC sub-layer

The physical layer is expected to perform the following

functions in order to provide the data transport service,

for example modulation/demodulation and

spreading/despreading, Inner - loop power control


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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); Overall description; Stage 2

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


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

Outline radio interface protocol stack

architecture

Describe key technology of UMTS physical

layer

Describe UMTS physical layer procedures


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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 Structure

RNS

RNC

RNS

RNC

Core Network

NodeB NodeB NodeB NodeB

Iu Iu

Iur

Iub IubIub Iub

UTRAN

User Equipment


7/52HUAWEI TECHNOLOGIES CO., LTD. All rights reserved Page 7

Radio Interface Protocol Structure

L3

control

control

control

con

trol

Logical

Channels

Transport

Channels

C-plane signaling U-plane information

PHY

L2/MAC

L1

RLC

DCNtGC

L2/RLC

MAC

RLCRLC

RLCRLC

RLC

RLCRLC

Duplication avoidance

UuS boundary

BMC L2/BMC

control

PDCPPDCP L2/PDCP

DCNtGC

Radio

Bearers

RRC


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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 datasymbol is called the Spreading FactorSF.The operation is done bymultiplying with OVSF code

Scrambling operationis applied to the spreading signal

Data bit

OVSF

code

Scrambling

code

Chips after

spreading


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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-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 Code

Scrambling code: GOLD sequence

Scrambling code period: 10ms ,or 38400 chips

The code used for scrambling of the uplink DPCCH/DPDCH may be of

either long or short type, There are 224long and 224short 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. scrambling codes k = 0, 1, , 8191 are used


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Scrambling

codes for

downlink

physical

channels

Set 0

Set 1

Set 511

Primary scrambling

code 0

Secondaryscrambling code 1

Secondary scrambling

code 15

Primaryscrambling code

51116

Secondaryscrambling code

5111615

8192 scrambling

codes512 sets

Primary Scrambling Code

A primary scrambling code and 15 secondary scrambling codes are

included in a set.


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Primary Scrambling Code Group

Primary

scrambling

codes for

downlink

physicalchannels

Group 0

Primary scramblingcode 0


638


6387

512 primary

scrambling codes

Group 1

Group 63

Primary scramblingcode 1

Primary scrambling

code 7

64 primary scrambling

code groups

Each group consists of 8

primary scrambling codes


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Section 1 Physical ChannelStructure 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 channeland 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 channeland

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 usesdedicated 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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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)

Logical Channel


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Dedicated Channel (DCH)

DCH is an uplink or downlink channel

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

Transport Channel


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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 Physical

Channel

Downlink Common Physical Channel

Common Control Physical Channel (CCPCH)Synchronization Channel (SCH)

Paging Indicator Channel (PICH)

Acquisition Indicator Channel (AICH)

Common Pilot Channel (CPICH)

High-Speed Physical Downlink SharedChannel (HS-PDSCH)

High-Speed Shared Control Channel

(HS-SCCH)


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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 ControlChannel (HS-DPCCH)

Uplink Common Physical Channel

Physical Random Access Channel (PRACH)

Uplink Physical

Channel


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Function of physical channel

Node B UE

P-CCPCH-Primary Common Control Physical Channel

SCH- Synchronisation Channel

P-CPICH-Primary Common Pilot ChannelS-CPICH-Secondary Common Pilot Channel

Cel l broadcast channels

DPDCH-Dedicated Physical Data Channel

DPCCH-Dedicated Physical Control Channel

Dedicated ch annels

Paging channels

PICH-Paging Indicator Channel

S-CCPCH-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 downl ink share channels


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Primary Synchronization Channel (P-SCH) Used for cell search

Two sub channels: P-SCH and S-SCH

SCH is transmitted at the first 256 chipsof every time slot

PSC is transmitted repeatedly in eachtime slot

SSC specifies the scrambling codegroups of the cell

SSC is chosen from a set of 16different codes of length 256, andthere are altogether 64 SSCsequences correspond to 64 primaryscrambling code groups

Primary SCH

Secondary SCH

Slot #0 Slot #1 Slot #14

acsi,0pac pac pac

acsi,1 acsi,14256 chips

2560 chips

One 10 ms SCH radio frame


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slot numberScramblingCode 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

Secondary Synchronization Channel (S-SCH)

..

2560 chips

acp

Slot # ?

P-SCH acp

Slot #?

16 6S-SCHacp

Slot #?

11 Group 2Slot 7, 8, 9

256 chips


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Carries pre-defined sequence

Fixed rate 30KspsSF=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 DPCH

Pre-defined symbol sequence

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

Tslot= 2560 chips , 20 bits

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 used

PCCPCH Data

18 bits

Slot #0

1 radio frame: Tf

= 10 ms

Slot #1 Slot #i

256 chips

Slot #14

Tslot

= 2560 chips,20 bits

SCH


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

One radio frame (10 ms)

b1b0

288 bits for paging indication 12 bits (undefined)b287 b288 b299


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Secondary Common Control Physical Channel (S-CCPCH)

Carry FACH and PCHTwo kinds of S-CCPCH: 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 - 4FACH and PCH can be mapped to the

same or separate S-CCPCHs. If

mapped to the same S-CCPCH, they

can be mapped to the same fame

DataN bits


1 radio frame: T f = 10 ms

T slot = 2560 chips,

Data

PilotN bitsPilotN bits

TFCI

TFCI

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


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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 consistsof 256 repetitions of a signature whose length is 16 chips, 16 availablesignatures totally

10 or 20ms message part

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

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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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 TransmissionAccess slot #8


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PRACH Message Structure

Pilot

N bits

Slot # 0Slot # 1 Slot # i

Slot # 14

Message part radio frame TRACH = 10 ms

Tslot = 2560 chips, 10*2

Pilot

TFCI

N bitsTFCI

Data

Ndata

bitsData

Control

kbits (k=0..3)


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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

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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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

Pilot

Npilot

bits

TPCNTPCbits

DataNdatabits


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

1 radio frame: T = 10 msf

DPDCH

DPCCHFBI

NFBIbitsTFCI

NTFCIbits


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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)

One radio frame, Tf = 10 ms


Tslot

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

Data2

Ndata2bits

DPDCH

TFCI

NTFCIbits

Pilot

NpilotbitsData1

Ndata1bits

DPDCH DPCCH DPCCH

TPC

NTPCbits


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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

Slot #0 Slot#1 Slot #2

T slot = 2560 chips, M*10*2kbits (k=4)

Data

N Data 1bits

1 subframe: Tf = 2 ms


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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 ksps, SF=128) downlink physical channel used to

carry downlink signalling related to HS-DSCH transmission

Slot #0 Slot#1 Slot #2

T slot= 2560 chips, 40 bits

DataN Data 1bits

1 subframe: T f = 2 ms


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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 control

Subframe #0 Subframe #i Subframe #4

HARQ-ACK CQI

One radio frame T = 10 ms

One HS-DPCCH subframe (2 ms)

2Tslot= 5120 chipsTslot= 2560 chips


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Section 1 Physical Channel Structure and Functions

Section 2 Channel Mapping


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Mapping Relation 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


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Synchronization ProcedureCell Search

Frame synchronization and

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 CPICHwith all codes within the identified group,

and then detects the P-CCPCH and

reads BCH information

Slot synchronizationUE uses PSC to acquire slot

synchronization to a cell


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Synchronization ProcedureChannel Timing Relationship

AICH accessslots

SecondarySCH

PrimarySCH

S-CCPCH,k

10 ms

PICH

#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 DPCHDPCH,n

Random Access Procedure


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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

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 Nackon AICH received

Choose a access slot again

Counter> 0 & Preamble power-

maximum allowed power


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Random Access ProcedureRACH

Physical random access procedure1. Derive the available uplink access slots, in the next full access

slot set, for the set of available RACH sub-channels within the

given ASC. Randomly select one access slot among the ones

previously determined. If there is no access slot available in the

selected set, randomly select one uplink access slot correspondingto the set of available RACH sub-channels within the given ASC

from the next access slot set. The random function shall be such

that each of the allowed selections is chosen with equal probability

2. Randomly select a signature from the set of available signatures

within the given ASC3. Set the Preamble Retransmission Counter to Preamble_

Retrans_ Max


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4. Set the parameter Commanded Preamble Power toPreamble_Initial_Power

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

preamble transmission power

6. If no positive or negative acquisition indicator (AI +1 nor1)

corresponding to the selected signature is detected in the downlink accessslot corresponding to the selected uplink access slot:

A: Select the next available access slot in the set of available RACH

sub-channels within the given ASC

B: select a signature

C: Increase the Commanded Preamble Power

D: Decrease the Preamble Retransmission Counter by one. If the

Preamble Retransmission Counter > 0 then repeat from step 6.

Otherwise exit the physical random access procedure


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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 Mode

Application of Tx diversity modes on downl ink 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


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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

b0 b1 b2 b3

-b2 b3 b0 -b1

Antenna 1

Antenna 2

Channel bits

STTD encoded channel bits

for antenna 1 and antenna 2.


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Transmit Diversity-TSTD

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

Antenna 1

Antenna 2

acsi,0

acp

acsi,1

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)


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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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02-WCDMA Radio Interface Physical Layer (1)