Doctoral Dissertation Studies on MIMO Spatial Multiplexing for High-Speed Wireless Communications Graduate School of Information Science and Technology Hokkaido University Hiroshi Nishimoto 2007 Contents 1 Introduction 1 1.1 Background . 1 1.2 Objectives of the Dissertation . 3 1.2.1 Measurement-Based Performance Evaluation of MIMO Spatial Mul- tiplexing . 4 1.2.2 Pseudo Eigenbeam Transmission for Frequency-Selective MIMO Channels . 5 1.3 Contents of the Dissertation . 6 2 MIMO Spatial Multiplexing 9 2.1 MIMO Flat-Fading Channel Model . 9 2.2 Generation of i.i.d. MIMO Channels Using Jakes Model . 10 2.2.1 Simplified Jakes Model . 11 2.2.2 Intra-Ring Condition . 13 2.2.3 Inter-Ring Condition . 13 2.2.4 Numerical Analysis . 14 2.2.5 Conclusions . 18 2.3 Spatial Multiplexing . 18 2.3.1 SDM . 19 2.3.2 E-SDM . 20 2.4 Demultiplexing Schemes in Spatial Multiplexing . 21 2.4.1 Zero-forcing . 21 2.4.2 Minimum Mean Square Error . 22 2.4.3 Maximum Likelihood Detection . 24 2.4.4 Serial Interference Canceller . 25 2.4.5 Parallel Interference Canceller . 29 2.5 MIMO SDM Performance Using Various Demultiplexing Schemes . 31 2.5.1 System Structure . 31 2.5.2 Computer Simulations . 32 3 MIMO Indoor Channel Measurement 39 3.1 Measurement Setup . 39 3.2 Example Measurements . 43 i Contents 3.3 TOA/DOA Estimation Using 2D-MUSIC Algorithm . 48 3.3.1 2D-MUSIC Algorithm . 48 3.3.2 Results of Propagation Estimation . 51 3.4 Estimation of Nakagami-Rice K-factor . 51 3.4.1 K-factor Calculation Using Average Channel Power . 56 3.4.2 K-factor Estimation Using CDF of Amplitudes . 57 4 Performance Evaluation of Spatial Multiplexing in Actual Indoor Environ- ments 61 4.1 Properties of Measured MIMO Channels . 61 4.1.1 Antenna Patterns . 61 4.1.2 Fading Correlations . 64 4.1.3 CDFs of Channel Elements in MIMO Matrices . 67 4.1.4 Eigenvalue Distribution . 73 4.2 Performance of Narrowband SDM . 78 4.2.1 SDM Channel Capacity . 78 4.2.2 BER Performance of SDM with ZF Spatial Filtering . 82 4.2.3 Conclusions . 85 4.3 Performance of Narrowband E-SDM . 86 4.3.1 E-SDM Channel Capacity . 86 4.3.2 BER Performance of E-SDM . 87 4.3.3 Conclusions . 96 4.4 Performance of Coded MIMO-OFDM SDM . 97 4.4.1 Simulation Conditions . 97 4.4.2 Simulation Results . 100 4.4.3 Conclusions . 103 5 Pseudo Eigenbeam-Space Division Multiplexing (PE-SDM) in Frequency-Selective MIMO Channels 105 5.1 Introduction . 105 5.2 MIMO Broadband System Model and E-SDM . 106 5.3 Pseudo Eigenvector Calculation . 109 5.3.1 Virtual RX Weight Matrix . 109 5.3.2 Pseudo Eigenvector Calculation . 109 5.3.3 Power Delay Profile of Effective Channels . 111 5.3.4 Numerical Complexity . 114 5.3.5 Pseudo Eigenvalue . 114 5.3.6 On Effects of Ordering in GS Processing . 116 5.4 Estimation Scheme of Effective Channel in PE-SDM . 117 5.4.1 Frequency Domain Estimation of Effective Channel . 117 5.4.2 Time-Windowing Scheme in PE-SDM . 120 5.5 MIMO-OFDM Computer Simulations . 121 5.5.1 System Structure . 121 ii Contents 5.5.2 Simulation Conditions . 123 5.5.3 Simulation Results . 124 5.6 Numerical Analysis in MIMO-SC Systems . 127 5.6.1 Power Delay Profile of Effective Channels . 127 5.6.2 Spatial Windowing and Space-Time Windowing . 130 5.6.3 System Structure . 131 5.6.4 Simulation Conditions . 133 5.6.5 Analysis of Channel Estimation Error . 137 5.6.6 Throughput Performance . 140 5.7 Conclusions . 144 6 PE-SDM Performance Evaluation Using Measured Channel Data 147 6.1 System Structure . 147 6.2 Simulation Conditions . 149 6.3 Throughput Performance of MIMO-OFDM PE-SDM in Actual Indoor En- vironments . 151 6.4 Conclusions . 161 7 Conclusions and Future Work 163 7.1 Summary . 163 7.2 Future Work . 165 References 167 A Scattering Coefficients for the Measured Antenna Arrays 177 B Gram-Schmidt Orthonormalization 183 C Amplitude Correction for MMSE Outputs 187 Acknowledgement 191 List of Publications and Awards 193 iii List of Tables 2.1 Computer simulation parameters. 34 3.1 MIMO channel measurement parameters. 40 3.2 2D-MUSIC estimation parameters. 51 4.1 Simulation parameters of MIMO SDM. 82 4.2 MIMO E-SDM and SDM simulation parameters. 91 4.3 Simulation parameters of MIMO-OFDM SDM. 98 4.4 RX fading correlations (averaged correlations for 4 4 MIMO). 103 × 5.1 RMS delay spreads of effective channels for a 4 4 MIMO case (Nf = 64).111 5.2 Mean and maximum numbers of complex multiplications× per fading state for 2 2 and 4 4 MIMO cases. 116 5.3 MIMO-OFDM× simulation× parameters. 122 5.4 Maximum numbers of complex multiplications at the receiver per frame for conventional frequency-domain channel estimation (FDCE), MMSE weight calculation, and time windowing (TW). 127 5.5 RMS delay spreads of effective channels in samples (Nf = 256). 129 5.6 MIMO-SC simulation parameters. 133 5.7 MCS for a 4 4 MIMO system part 1 (1–7 bits per SDM-symbol). 135 5.8 MCS for a 4 × 4 MIMO system part 2 (7.5–18 bits per SDM-symbol). 136 5.9 Maximum numbers× of complex multiplications at the receiver per block for FDCE, MMSE, and three windowing schemes in the 4 4 MIMO case. 141 × 6.1 MIMO-OFDM simulation parameters. 150 B.1 Algorithm of GS orthonormalization. 184 B.2 Algorithm of norm-ordered GS orthonormalization. 185 v List of Figures 1.1 Outline of the dissertation. 8 2.1 Concept of a MIMO channel. 9 2.2 Concept of an i.i.d. time-varying MIMO channel model using multiple Jakes rings (Ntx = Nrx = 2). 12 2.3 Simplified Jakes model. 12 2.4 Examples of SISO channels based on Jakes model. 15 2.5 10%-value CDFs of amplitudes for SISO cases. 16 2.6 10%-value CDFs of eigenvalues for 2 2 MIMO cases. 17 2.7 10%-value CDFs of SISO channels under× the intra-ring condition in the cases of M = 12, 24, and 36. 18 2.8 Concepts of SDM and B-SDM. 19 2.9 Concept of E-SDM transmission. 20 2.10 Concept of SIC. 25 2.11 Concept of PIC. 30 2.12 System structure in a case of CPS. 32 2.13 System structure in a case of COS. 33 2.14 BER performance in the no coding case. 35 2.15 BER and FER performances in the CPS case. 36 2.16 BER and FER performances in the COS case. 37 3.1 Top view of measurement site. 40 3.2 Pictures of measurement site. 41 3.3 Antenna array orientations. 42 3.4 Isolated azimuthal antenna pattern of a measurement antenna at 5.2 GHz. 43 3.5 Channel measurement system. 44 3.6 Measurement table including antennas (top), RF switch (middle), and RF switch controller (bottom). 45 3.7 Example measurements (SISO case). 46 3.8 Examples of eigenvalues for the 2 2 MIMO case (AS = 0.50λ, TX-y/RX- y orientation). .× . ..