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

Downlink Multi-user MIMO Decoding and Demodulation 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 Decoder Demapper Channel estimation MMSE CINR measurement

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

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

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

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

2. MIMO scheme set 2.3 Advantages SM IEEE802.16e Matrix C Proposal Decoding complexity High(2x2 ML) Low (2x2 MMSE) High (4x4 ML) Moderate (4x4 MMSE) Encoding complexity Low (no manipulation on signal) High (signal multiplication & addition) Moderate (signal rotation & reconstruction) Performance Better, especially in high code rate

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

2. MIMO scheme set 2.4.2 Simulation result MMSE receiver

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

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 Rx Nr Nt Feedback information Precoding W s1 s2 . sm

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

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

2. MIMO scheme set 2.8 STC-HARQ (IEEE802.16e) Initial transmission Odd retransmission Even retransmission 2 Tx 4 Tx Alamouti pair

2. MIMO scheme set Alternative 1 Alternative 2 Alternative 3 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

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

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