wcdma air interface training part 6 wcdma tdd mode

Part 6: 1 of 176/038 13 - EN/LZU 108 5306 Rev A WCDMA Air Interface

WCDMA Air Interface Training

Part 6 WCDMA TDD Mode


WCDMA TDD Mode

• Time-Domain Duplex (TDD) Mode

Benefits

Used where paired frequency bands are not available

Total system deployment in 5 MHz of spectrum

Asymmetrical RF Channel

Disadvantages

Discontinuous Transmission (EMI)

Frame synchronization is required to prevent UL/DL collisions

Requires precise timing control of UE transmission


WCDMA TDD Mode• Comparison of FDD and TDD Modes

FDD TDD

Chip Rate 3.840 Mcps

Slot 0.666 msec

Frame 10 msec

Error Protection Convolutional Codes (R=1/2, 1/3)

Turbo Codes (R=1/3)

Interleaving 10, 20, 40, and 80 msec

Modulation QPSK , RRC filter = 0.22

Acquisition Primary and Secondary 256-chip Synchronization Codes

Power Control UL: Closed-loop, 1500 Hz DL: Closed-loop, 1500 Hz

UL: Open-Loop, 100/200 Hz DL: Closed-Loop, 800 Hz

Cell time sync Not Required Required

Orthogonal Codes

Hadamard OVSF [4, 8, … 512]

Hadamard OVSF [1, 2, 4, 8, 16]

Variable Data Rate OVSF, Multi-Code OVSF, Multi-Code, Multi-Slot

Coherent Detection

Embedded Pilot Symbols Midamble synchronization words

Handover Soft or Hard Handover Hard Handover Only

(1.28 Mcps TDD under development)


WCDMA TDD Mode• WCDMA Code Layering (TDD vs. FDD)

FDDDOWNLI NK

FDDUPLI NK

TDDDOWNLI NK

TDDUPLI NK

OVSF DataChannelizationCodes

OVSF4 ~ 512 chips

OVSF4 ~ 256 chips

OVSF{ 1 or 16 chips )

OVSF{ 1 , 2, 4, 8, or 16

chips )

OVSF ModulationSymbolRate

960 ksps ~ 7.5 ksps 960 ksps ~ 15 ksps 3.84 Msps, 240 ksps3.84 Msps ~

240 ksps

ScramblingCodes(DistinguishesBTS or UE)

Complex (I ,jQ) Code38,400 chips of a

218 Gold Sequence

Complex (I ,jQ) Code38,400 chips of a225 Gold Sequence

or256-chip S(2) code

* multiplied byHPSK rotator codes

Code length same as OVSF length( 1 , 2, 4, 8, or 16 chips )

127 scrambling codes specified inTS25.223 V 3.0.0 Annex A

Each cell has a specific scrambling codefrom the group of 127 codes


BCCHBroadcast Control Ch.

PCCHPaging Control Ch.

CCCHCommon Control Ch.

DCCHDedicated Control Ch.

DTCHDedicated Traffic Ch. N

BCHBroadcast Ch.

PCHPaging Ch.

FACHForward Access Ch.

DCHDedicated Ch.

P-CCPCH(*)Primary Common Control Physical Ch.

S-CCPCHSecondary Common Control Physical Ch.

DPDCH (up to 14 per carrier) Dedicated Physical Data Ch.

TFCI bits

SSCi

Logical Channels(Layers 3+)

Transport Channels(Layer 2)

Physical Channels(Layer 1)

DownlinkRF Out

DSCHDownlink Shared Ch.

SHCCHDSCH Control Ch.

CTCHCommon Traffic Ch.

Data Encoding

Data Encoding

Data Encoding

Data Encoding

Data Encoding

PDSCHPhysical Downlink Shared Channel

PICH (Paging Indication Channel )

Paging Indication bits S/P

S/P

S/P

S/P

S/P

Cell-specificScrambling

Code

I+jQ I/QModulator

Q

I

Cch

Cch

Cch

Cch

Cch 256,1

GS

PSC

GP

Sync Codes(*)

* Note regarding P-CCPCH and SCH

Sync Codes are transmitted only in bits 0-255 of each timeslot;P-CCPCH transmits only during the remaining bits of each timeslot

Filter

Filter

Gain

Gain

Gain

Gain

SCH (Sync Channel)

DTCHDedicated Traffic Ch. 1

DCHDedicated Ch.

Data Encoding

MUX

CCTrCH

DCHDedicated Ch.

Data Encoding

WCDMA Downlink (TDD)


Logical Channels(Layers 3+)

Transport Channels(Layer 2)

UplinkRF Out

UEScrambling

Code

I+jQ I/QMod.

Q

IFilter

Filter

CCCHCommon Control Ch.

RACHRandom Access Ch.

PRACHPhysical Random Access Ch.

DPDCH #1Dedicated Physical Data Ch.

Data Coding

DPDCH #2 (optional)Dedicated Physical Data Ch.

DPDCH #3 (optional) Dedicated Physical Data Ch.

DPDCH #16 (optional) Dedicated Physical Data Ch.TPC, TFCI bits

RACH Control Part

DCCHDedicated Control Ch.

DTCHDedicated Traffic Ch. N

DCHDedicated Ch.

Data Encoding

DTCHDedicated Traffic Ch. 1

DCHDedicated Ch.

Data Encoding

MUX

CCTrCH

DCHDedicated Ch.

Data Encoding

USCHDownlink Shared Ch.

SHCCHUSCH Control Ch.

Data Encoding

PUSCHPhysical Uplink Shared Channel

S/P

Cch Gain

S/P

Cch Gain

S/P

Cch Gain

S/P

Cch Gain

S/P

Cch Gain

S/P

Cch Gain

WCDMA Uplink (TDD)


WCDMA TDD Frame Formats

• At least one slot per frame must be allocated for UL, DL

15 Slots per Frame , 0.666 mSec per slot, 10 mSec total

Multiple switching points; Symmetric DL/UL

Multiple switching points; Asymmetric DL/UL

Single switching point; Symmetric DL/UL

Single switching point; Asymmetric DL/UL

Examples of valid TDD frame formats

3GPP TS 25.2213GPP TS 25.221


WCDMA TDD Burst Structures

2560 Chips (0.666 msec)

PSC

TDD Synchronization Burst

•Uses similar SCH codes as FDD mode•Provides slot synchronization and Cell Scrambling Code Group ID•Transmitted DL only, one or two slots per frame (any slot)

3GPP TS 25.2213GPP TS 25.221

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

1 Frame = 15 slots = 10 mSec

SSC1

SSC2

SSC3

toffsetSyncBurst

•Toffset reduces the probability that a UE will receive conflicting SCH bursts from multiple cells•Toffset is one of 32 possible values, changes from frame to frame, based on the Cell Code Group


WCDMA TDD Burst Structures

Midamble512 chips

Data976 Chips

GP96

2560 Chips (0.666 msec)

TrafficBurst

Type I

Data976 Chips

Midamble256 chips

Data1104 Chips

GP96

Data1104 Chips

TrafficBurst

Type II

Longer Midamble for UL, where every slot may require new synchronization

Shorter Midamble for DL, where synchronization is consistent on every slot.Also used in UL when less than 4 users per timeslot

TPC

TFCI

TFCI

TPC

TFCI

TFCI

Notes: •TFCI and TPC are included in the length of data fields.•TFCI and TPC are subject to same Channelization and Scrambling Codes as the data fields.•TPC is UL only and must be transmitted at least once per frame•TFCI is optional

3GPP TS 25.2213GPP TS 25.221

Midamble512 chips

Data880 Chips

GP192

Random Access

Burst

Data976 Chips


WCDMA TDD Multicode Transmission

Data976 Chips

GP96

2560 Chips (0.666 msec)

Data976 Chips

TPC

TFCI

TFCI

3GPP TS 25.2213GPP TS 25.221

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

1 Frame = 15 slots = 10 mSec

Data976 Chips

GP96

Data976 Chips

TPC

TFCI

TFCI

Data976 Chips

GP96

Data976 Chips

TPC

TFCI

TFCI

ChannelizationCode 1

ChannelizationCode 2

ChannelizationCode N

( Midambles are not coded )


WCDMA TDD Slot Formats3GPP TS 25.221

3GPP TS 25.221

Slot Format

#

Spreading Factor

Midamble length (chips)

TFCI bits/slot

Data bits/slot

Data Rate kbps/slot

0 0 244 24.4 1 4 240 24.0 2 8 236 23.6 3 16 228 22.8 4

512

32 212 21.2 5 0 276 27.6 6 4 272 27.2 7 8 268 26.8 8 16 260 26.0 9

16

256

32 244 24.4

10 0 3904 390.4 11 4 3900 390.0 12 8 3896 389.6 13 16 3888 388.8 14

512

32 3872 387.2 15 0 4416 441.6 16 4 4412 441.2 17 8 4408 440.8 18 16 4400 440.0 19

1

256

32 4384 438.4

TDD Downlink Slot FormatsNote:

Data Rates are post-error correction, and include TFCI bits

Data rates shown are for SF=1


WCDMA TDD Slot Formats3GPP TS 25.221

3GPP TS 25.221

TDD Uplink Slot Formats(Partial listing)

Slot Format

#

Spreading Factor

Midamble length (chips)

TFCI bits/slot

TPC bits/slot

Data bits/slot

Data Rate kbps/slot

0 16 512 0 0 244 24.4 19 16 256 32 2 242 24.2 20 8 512 0 0 488 48.8 39 8 256 32 2 518 51.8 40 4 512 0 0 976 97.6 59 4 256 32 2 1070 107.0 60 2 512 0 0 1952 195.2 79 2 256 32 2 2174 217.4 80 1 512 0 0 3904 390.4 99 1 256 32 2 4282 428.2

Data Rates are post-error correction, SF=1, and include TFCI and TPC bits


TDD Data Coding, Multiplexing

Turbo Coding R=1/3

240

#2 1950#1 1950

1204

1150 * 54

Radio frame FN=4N+1 Radio frame FN=4N+2 Radio frame FN=4N+3Radio frame FN=4N

Traffic data (1280x2)

2nd interleaving 1204 1204 1204

1150 54 1150 54 1150 * 54

3888

1280 Terminationbits

CRC16

240

100

96CRC 12 + TAIL 8

Rate matching

Layer 3 Control data

Conv. Coding R=1/2

Radio FrameSegmentation

5 code channelsSF = 16

TFCI only in ch. 1

Rate matching

1st interleaving

1280

Traffic @ 64 kbpsTraffic @ 64 kbps L3 Data @ 2.4 kbpsL3 Data @ 2.4 kbps3GPP TS 25.102 App. A

3GPP TS 25.102 App. A

Add CRC bits Add CRC bits

12

* Data from second 3840-bit packet

#2 1150#1 1150

39001st interleaving

4

Radio FrameSegmentation

#1 60 #2 60 #3 60 #4 60

#1 54 #2 54 #3 54 #4 54

122 MA 122

122 MA 122

122 MA 122

122 MA 122

114 MA 114TFCI

TFCI

8 8

122 MA 122

122 MA 122

122 MA 122

122 MA 122

114 MA 114TFCI

TFCI

8 8

122 MA 122

122 MA 122

122 MA 122

122 MA 122

114 MA 114TFCI

TFCI

8 8

122 MA 122

122 MA 122

122 MA 122

122 MA 122

114 MA 114TFCI

TFCI

8 8


WCDMA TDD Power Control

• Power Control not as critical as FDD mode

• UE transmit power updated through open-loop SIR calculation UE can determine uplink path loss based on downlink measurement

• BS transmit power updated once or twice per frame via TPC commands sent from UE

3GPP TS 25.2213GPP TS 25.221


WCDMA TDD Timing Advance

• UTRAN adjusts UE timing via signaling message

• Timing advance of [0, 1, ... 63] x 4 chips

66.66 uSec range (~ 10 km range adjustment)

3GPP TS 25.2213GPP TS 25.221


TDD Dynamic Channel Assignment

• DCA Improves allocation of resources Highly loaded cell can “borrow” channels a lightly loaded cell (Slow DCA)

Channels may be allocated between cells to support a handover (Slow DCA)

Timeslots and Codes can be reallocated dynamically within a cell (Fast DCA)

3GPP TS 25.2213GPP TS 25.221

Cell 1Cell 2

UTRANUTRAN In this example, the

UTRAN may allocate more frequencies to Cell 1;

fewer to Cell 2


WCDMA TDD Mode Summary

• TDD Mode shares many characteristics with FDD Chip rate

Slot and Frame Structures

Synchronization Codes

Error protection coding and Interleaving

Filtering and Modulation

• TDD Benefits Can be deployed in 5 MHz total spectrum

Allows asymmetric UL/DL data

• Spreading Factors from 1 to 16 Allow multiple users to share one time slot

Peak data rates comparable to FDD mode

• Cell site time synchronization is required

3GPP TS 25.2213GPP TS 25.221

wcdma air interface training part 6 wcdma tdd mode

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