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2 and 4 Tx MIMO System

CJK-B3G #11. 2 and 4 Tx MIMO System. 10-11 April 2006. Contents. 1. Introduction 2. MIMO scheme set Two Tx scheme Four Tx scheme Closed-loop scheme for rate-1 STC-HARQ scheme. Decoder. Demapper. 1. Introduction. 1.1 Overall system. Feedforward. Feedback. MIMO. OFDM Tx.

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2 and 4 Tx MIMO System

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  1. CJK-B3G #11 2 and 4 Tx MIMO System 10-11 April 2006

  2. Contents 1. Introduction 2. MIMO scheme set • Two Tx scheme • Four Tx scheme • Closed-loop scheme for rate-1 • STC-HARQ scheme

  3. Decoder Demapper 1. Introduction 1.1 Overall system Feedforward Feedback MIMO OFDM Tx Coding and Modulation LDC scheme MIMO-Pilot Downlink Multi-user MIMO PAPR reduction scheme Channel coder Modulation Uplink MIMO Sub-carrier allocation Scheduler H-ARQ, Power control, MCS adaptation, Bit loading, Per stream power control, Per antenna rate control, OFDM mode change, MIMO mode change Channel Feedback overhead reduction OFDM Rx Decoding and Demodulation MIMO Demodulator Synchronization MLD or QRM-MLD Channel estimation MMSE CINR measurement

  4. 1. Introduction 1.2 LDC (Linear dispersion code) [’02 Heath, ’02 Hassibi] • Nt, Nr : number of transmit and receive antennas • T : LDC period • Q : number of symbols • Aq, Bq : T x Nt dispersion matrix • ai, bi : real and imaginary value of ith symbol • Every multi-antenna transmit scheme can be expressed in form of LDC • Ex. Alamouti scheme

  5. Equivalent channel model 1. Introduction 1.3 Design criterion • Pairwise error probability (PEP) • Capacity

  6. 2. MIMO scheme set 2.1 Two Tx Rate-1 Scheme [’98 Alamouti] 2.2 Two Tx Rate-2 Scheme [LGE proposal] 2.2.1 Another candidates

  7. 2. MIMO scheme set 2.2.2 Simulation result CF> IEEE802.16 Matrix-C has identical performance with the proposal

  8. 2. MIMO scheme set 2.3 Advantages

  9. 2. MIMO scheme set 2.4 Four Tx Rate-1 scheme [’04 Sethuraman] 2.4.1 Another candidates

  10. 2. MIMO scheme set 2.4.2 Simulation result MMSE receiver

  11. 2. MIMO scheme set 2.5 Four Tx Rate-2 scheme [’04 Sethuraman] 2.6 Four Tx Rate-4 scheme

  12. s1 s2 . . . sm Precoding W Rx Nr Nt Feedback information 2. MIMO scheme set 2.7 Closed-loop MIMO 2.7.1 Codebook • A set of pre-defined precoding matrices • Moderate feedback overhead (3~6 bits) • Selection criteria [‘03 Love] • ML • MMSE

  13. 2. MIMO scheme set 2.7.2 Four tx rate-1 closed-loop scheme [LGE proposal] 2.7.3 Advantage over codebook approach • Low feedback overhead (1 bit) • Less sensitive to mobility because of using channel statistics

  14. 30km/h & 5ms feedback delay 30km/h & 2ms feedback delay or 20km/h & 3ms feedback delay 2. MIMO scheme set 2.7.4 Simulation • Codebook size: 8 • (3bit feedback required) • Proposed scheme • (1bit feedback required)

  15. 2. MIMO scheme set 2.8 STC-HARQ (IEEE802.16e) Alamouti pair

  16. 2. MIMO scheme set 2.8.1 Adaptive STC-HARQ [LGE proposal] Alternative 1 Alternative 2 Alternative 3 ACK/NACK signals (2bits): • ACK, • NACK w/ alt 1, • NACK w/ alt 2, • NACK w/ alt 3

  17. 2. MIMO scheme set 2.8.2 Simulation Results • 802.16e system • 20ms difference between transmission and retransmission

  18. Thanks

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