Post on 13-Jan-2016
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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
Part 6: 2 of 176/038 13 - EN/LZU 108 5306 Rev A WCDMA Air Interface
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
Part 6: 3 of 176/038 13 - EN/LZU 108 5306 Rev A WCDMA Air Interface
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)
Part 6: 4 of 176/038 13 - EN/LZU 108 5306 Rev A WCDMA Air Interface
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
Part 6: 5 of 176/038 13 - EN/LZU 108 5306 Rev A WCDMA Air Interface
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)
Part 6: 6 of 176/038 13 - EN/LZU 108 5306 Rev A WCDMA Air Interface
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)
Part 6: 7 of 176/038 13 - EN/LZU 108 5306 Rev A WCDMA Air Interface
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
Part 6: 8 of 176/038 13 - EN/LZU 108 5306 Rev A WCDMA Air Interface
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
Part 6: 9 of 176/038 13 - EN/LZU 108 5306 Rev A WCDMA Air Interface
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
Part 6: 10 of 176/038 13 - EN/LZU 108 5306 Rev A WCDMA Air Interface
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 )
Part 6: 11 of 176/038 13 - EN/LZU 108 5306 Rev A WCDMA Air Interface
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
Part 6: 12 of 176/038 13 - EN/LZU 108 5306 Rev A WCDMA Air Interface
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
Part 6: 13 of 176/038 13 - EN/LZU 108 5306 Rev A WCDMA Air Interface
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
Part 6: 14 of 176/038 13 - EN/LZU 108 5306 Rev A WCDMA Air Interface
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
Part 6: 15 of 176/038 13 - EN/LZU 108 5306 Rev A WCDMA Air Interface
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
Part 6: 16 of 176/038 13 - EN/LZU 108 5306 Rev A WCDMA Air Interface
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
Part 6: 17 of 176/038 13 - EN/LZU 108 5306 Rev A WCDMA Air Interface
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