WCDMA Air Interface Training Part 6 WCDMA TDD Mode

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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) - PowerPoint PPT Presentation

Transcript of WCDMA Air Interface Training Part 6 WCDMA TDD Mode

Fundamentals of W-CDMA Part IV IMT-2000 W-CDMA Proposals6/038 13 - EN/LZU 108 5306 Rev A WCDMA Air Interface
WCDMA Air Interface Training
6/038 13 - EN/LZU 108 5306 Rev A WCDMA Air Interface
WCDMA TDD Mode
Asymmetrical RF Channel
Requires precise timing control of UE transmission
6/038 13 - EN/LZU 108 5306 Rev A WCDMA Air Interface
WCDMA TDD Mode
(1.28 Mcps TDD under development)
FDD
TDD
Turbo Codes (R=1/3)
Modulation
Power Control
Variable
6/038 13 - EN/LZU 108 5306 Rev A WCDMA Air Interface
WCDMA TDD Mode
FDD DOWNLINK
OVSF Modulation
Symbol Rate
Complex (I,jQ) Code
Complex (I,jQ) Code
or
( 1 , 2, 4, 8, or 16 chips )
127 scrambling codes specified in TS25.223 V 3.0.0 Annex A
Each cell has a specific scrambling code from the group of 127 codes
6/038 13 - EN/LZU 108 5306 Rev A WCDMA Air Interface
BCCH
S-CCPCH
DPDCH (up to 14 per carrier)
Dedicated Physical Data Ch.
* Note regarding P-CCPCH and SCH
Sync Codes are transmitted only in bits 0-255 of each timeslot;

6/038 13 - EN/LZU 108 5306 Rev A WCDMA Air Interface
Logical Channels
(Layers 3+)
Transport Channels
(Layer 2)
6/038 13 - EN/LZU 108 5306 Rev A WCDMA Air Interface
WCDMA TDD Frame Formats
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Examples of valid TDD frame formats
3GPP TS 25.221
6/038 13 - EN/LZU 108 5306 Rev A WCDMA Air Interface
WCDMA TDD Burst Structures
2560 Chips (0.666 msec)
Provides slot synchronization and Cell Scrambling Code Group ID
Transmitted DL only, one or two slots per frame (any slot)
3GPP TS 25.221
SSC1
SSC2
SSC3
toffset
Sync
Burst
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
6/038 13 - EN/LZU 108 5306 Rev A WCDMA Air Interface
WCDMA TDD Burst Structures
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
T
P
C
T
F
C
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C
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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 25.221
6/038 13 - EN/LZU 108 5306 Rev A WCDMA Air Interface
WCDMA TDD Multicode Transmission
Data
6/038 13 - EN/LZU 108 5306 Rev A WCDMA Air Interface
WCDMA TDD Slot Formats
Data rates shown are for SF=1
Slot Format
6/038 13 - EN/LZU 108 5306 Rev A WCDMA Air Interface
WCDMA TDD Slot Formats
(Partial listing)
Data Rates are post-error correction, SF=1, and include TFCI and TPC bits
Slot Format
6/038 13 - EN/LZU 108 5306 Rev A WCDMA Air Interface
TDD Data Coding, Multiplexing
Turbo Coding R=1/3
Radio frame FN=4N
Rate matching
1st interleaving
Add CRC bits
Add CRC bits
#2 1150
#1 1150
6/038 13 - EN/LZU 108 5306 Rev A WCDMA Air Interface
WCDMA TDD Power Control
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 25.221
6/038 13 - EN/LZU 108 5306 Rev A WCDMA Air Interface
WCDMA TDD Timing Advance
Timing advance of [0, 1, ... 63] x 4 chips
66.66 uSec range (~ 10 km range adjustment)
3GPP TS 25.221
6/038 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 25.221
UTRAN
In this example, the UTRAN may allocate more frequencies to Cell 1; fewer to Cell 2
6/038 13 - EN/LZU 108 5306 Rev A WCDMA Air Interface
WCDMA TDD Mode Summary
Chip rate
Filtering and Modulation
Allows asymmetric UL/DL data
Allow multiple users to share one time slot
Peak data rates comparable to FDD mode
Cell site time synchronization is required
3GPP TS 25.221
Turbo Codes (R=1/3)
Modulation
Vari
able
chips )
( 1 , 2, 4, 8, or 16 chips )
127 scrambling codes specified in
TS25.223 V 3.0.0 Annex A
Each cell has a specific scrambling code
from the group of 127 codes
Slot
Format