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WCDMA Air Interface Training Part 6 WCDMA TDD Mode

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)

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WCDMA Air Interface Training Part 6 WCDMA TDD Mode

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  1. WCDMA Air Interface TrainingPart 6 WCDMA TDD Mode

  2. 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

  3. WCDMA TDD Mode • Comparison of FDD and TDD Modes (1.28 Mcps TDD under development)

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

  5. WCDMA Downlink (TDD) Logical Channels(Layers 3+) Transport Channels(Layer 2) Physical Channels(Layer 1) Sync Codes(*)  BCCHBroadcast Control Ch. BCHBroadcast Ch. Data Encoding P-CCPCH(*)Primary Common Control Physical Ch. S/P PSC  Cch 256,1 Gain GP PCCHPaging Control Ch. PCHPaging Ch. Data Encoding SSCi S-CCPCHSecondary Common Control Physical Ch. S/P SCH (Sync Channel) CCCHCommon Control Ch. GS Cch Gain FACHForward Access Ch. Data Encoding CTCHCommon Traffic Ch. Cell-specificScramblingCode DownlinkRF Out DCCHDedicated Control Ch. DCHDedicated Ch. Data Encoding DTCHDedicated Traffic Ch. 1 DCHDedicated Ch. Data Encoding CCTrCH I/QModulator I DPDCH (up to 14 per carrier) Dedicated Physical Data Ch. I+jQ S/P Filter  MUX Filter Cch Gain Q DTCHDedicated Traffic Ch. N DCHDedicated Ch. Data Encoding TFCI bits * 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 SHCCHDSCH Control Ch. DSCHDownlink Shared Ch. Data Encoding PDSCHPhysical Downlink Shared Channel S/P Cch Gain PICH (Paging Indication Channel ) S/P Paging Indication bits Cch

  6. WCDMA Uplink (TDD) Logical Channels(Layers 3+) Transport Channels(Layer 2)  CCCHCommon Control Ch. RACHRandom Access Ch. Data Coding PRACHPhysical Random Access Ch. S/P Cch Gain RACH Control Part UEScramblingCode SHCCHUSCH Control Ch. USCHDownlink Shared Ch. Data Encoding PUSCHPhysical Uplink Shared Channel S/P UplinkRF Out Cch Gain I/QMod. I I+jQ Filter Filter Q CCTrCH DCCHDedicated Control Ch. DCHDedicated Ch. Data Encoding DPDCH #1Dedicated Physical Data Ch. S/P DTCHDedicated Traffic Ch. 1 DCHDedicated Ch. Data Encoding Cch Gain DPDCH #2 (optional)Dedicated Physical Data Ch. S/P Cch Gain DPDCH #3 (optional) Dedicated Physical Data Ch. S/P MUX Cch Gain DTCHDedicated Traffic Ch. N DCHDedicated Ch. Data Encoding DPDCH #16 (optional) Dedicated Physical Data Ch. S/P TPC, TFCI bits Cch Gain

  7. WCDMA TDD Frame Formats 3GPP TS 25.221 • 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 Examples of valid TDD frame formats ¯ ­ ¯ ­ ¯ ­ ¯ ­ ¯ ­ ¯ ­ ¯ ­ ¯ Multiple switching points; Asymmetric DL/UL ¯ ¯ ¯ ­ ¯ ¯ ¯ ­ ¯ ¯ ¯ ­ ¯ ¯ ¯ Single switching point; Symmetric DL/UL ¯ ¯ ¯ ¯ ¯ ¯ ¯ ¯ ­ ­ ­ ­ ­ ­ ­ Single switching point; Asymmetric DL/UL ¯ ¯ ¯ ¯ ¯ ¯ ¯ ¯ ¯ ¯ ¯ ¯ ­ ­ ­

  8. WCDMA TDD Burst Structures 3GPP TS 25.221 • 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) 1 Frame = 15 slots = 10 mSec 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 PSC toffset SyncBurst SSC1 SSC2 SSC3 2560 Chips (0.666 msec) • 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

  9. WCDMA TDD Burst Structures 3GPP TS 25.221 2560 Chips (0.666 msec) TrafficBurstType I Data976 Chips TFCI Midamble512 chips Data976 Chips TPC TFCI GP96 Longer Midamble for UL, where every slot may require new synchronization TrafficBurstType II Data1104 Chips TFCI Midamble256 chips Data1104 Chips TPC TFCI GP96 Shorter Midamble for DL, where synchronization is consistent on every slot.Also used in UL when less than 4 users per timeslot Random AccessBurst Data976 Chips Midamble512 chips Data880 Chips GP192 • 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

  10. WCDMA TDD Multicode Transmission 3GPP TS 25.221 2560 Chips (0.666 msec) Data976 Chips TFCI ( Midambles are not coded ) Data976 Chips TPC TFCI GP96 ChannelizationCode 1 Data976 Chips TFCI TPC Data976 Chips TFCI GP96 ChannelizationCode 2 Data976 Chips TFCI TPC Data976 Chips TFCI GP96 ChannelizationCode N 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 1 Frame = 15 slots = 10 mSec

  11. WCDMA TDD Slot Formats 3GPP TS 25.221 TDD Downlink Slot Formats Note: Data Rates are post-error correction, and include TFCI bits Data rates shown are for SF=1

  12. WCDMA TDD Slot Formats 3GPP TS 25.221 TDD Uplink Slot Formats(Partial listing) Data Rates are post-error correction, SF=1, and include TFCI and TPC bits

  13. 1150 54 1150 54 1150 * 54 1150 * 54 122 122 122 122 MA MA MA MA 122 122 122 122 122 122 122 122 MA MA MA MA 122 122 122 122 122 122 122 122 MA MA MA MA 122 122 122 122 122 122 122 122 MA MA MA MA 122 122 122 122 114 114 114 114 TFCI TFCI TFCI TFCI MA MA MA MA TFCI TFCI TFCI TFCI 114 114 114 114 8 8 8 8 8 8 8 8 TDD Data Coding, Multiplexing 3GPP TS 25.102 App. A Traffic @ 64 kbps L3 Data @ 2.4 kbps 1280 Traffic data (1280x2) Layer 3 Control data 4 96 CRC16 CRC 12 + TAIL 8 Add CRC bits 1280 100 Add CRC bits Terminationbits Conv. Coding R=1/2 Turbo Coding R=1/3 240 3888 12 1st interleaving 3900 1st interleaving 240 Radio FrameSegmentation Radio FrameSegmentation #1 60 #2 60 #3 60 #4 60 #1 1950 #2 1950 Rate matching #1 54 #2 54 #3 54 #4 54 Rate matching #1 1150 #2 1150 * Data from second 3840-bit packet 2nd interleaving 1204 1204 1204 1204 5 code channelsSF = 16TFCI only in ch. 1 Radio frame FN=4N Radio frame FN=4N+1 Radio frame FN=4N+2 Radio frame FN=4N+3

  14. WCDMA TDD Power Control 3GPP TS 25.221 • 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

  15. WCDMA TDD Timing Advance 3GPP TS 25.221 • UTRAN adjusts UE timing via signaling message • Timing advance of [0, 1, ... 63] x 4 chips • 66.66 uSec range (~ 10 km range adjustment)

  16. TDD Dynamic Channel Assignment 3GPP TS 25.221 • 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) UTRAN In this example, the UTRAN may allocate more frequencies to Cell 1; fewer to Cell 2 Cell 2 Cell 1

  17. WCDMA TDD Mode Summary 3GPP TS 25.221 • 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

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