Wireless Communications Signal Processing Perspectives

Chapter2.pdf......Page 0
1 Linerar Diversity Techniques for Fading Channels......Page 35
1.1. System and Fading Channel Models......Page 38
1.2. Transmision without diversity......Page 42
1.3. Spectral Diversity......Page 44
1.4. Temporal Diversity......Page 50
1.4.1. Spread-Response Precoding......Page 51
1.4.2. Incorporating Bandwidth Expansion......Page 57
1.5. Diversity Methods for Multiuser Systems......Page 59
1.5.1. Multiuser Fading Channels......Page 60
1.5.2. Multiple Access and Multiplexing formats......Page 61
1.5.3. Orthogonal Multiuser Modulation......Page 63
1.5.4. Spread-Signature CDMA Systems......Page 65
1.5.5. CDMA Performance Characteristics......Page 69
1.5.7. Efficient Implementations of Spread-Response Precoding......Page 74
1.6. Spatial Diversity......Page 76
1.6.1. Receiver Antenna Diversity......Page 77
1.6.2. Transmitter Antenna Diversity......Page 80
1.6.2.1. Beamforming Diversity with Feedback......Page 81
1.6.2.2. Linear Antenna Precoding......Page 82
1.6.2.3. Dual-form Linear Antenna Precoding......Page 88
1.6.2.4. Incorporating Bandwidth Expansion......Page 93
1.7. Concluding Remarks......Page 94
2 Adaptative Interference Suppresion......Page 98
2.1. Multiple-Access Signel Model......Page 99
2.2. Elements of Multiuser Detection......Page 101
2.3. Linear Interference Suppression......Page 104
2.3.1. Multiple-Input/Multiple-output (MIMO) Minumum Mean-Squared Error (MMSE) Linear Detector......Page 105
2.3.2. Zero-Forcing (Decorrelating) Detector......Page 108
2.3.3. Inplementation as a Tapped-Delay Line (TDL)......Page 110
2.4. Application to DS-CDMA......Page 112
2.4.1. Discrete-Time Representation......Page 113
2.4.2. Complutation of MMSE Coefficients......Page 115
2.4.3. Geometric Interpretation......Page 117
2.4.4. Zero-Forcing (Decorrelating) Solution......Page 119
2.4.6. Preformance Measures......Page 120
2.4.7. Space-Time Filtering......Page 122
2.4.8. Effect of Multipath......Page 123
2.5. Adaptative Algoritms......Page 124
2.5.1. Stochastic Gradient Algorithm......Page 125
2.5.2. Least Squares (LS) Algorithm......Page 127
2.5.3. Orthogonally Anchored (Blind) Algoritms......Page 129
2.5.4. Projection-Based Approached......Page 135
2.5.5. Numerical Examples......Page 136
2.6.1. The Mobile Wireless Environment......Page 140
2.6.1.1. Distance-Related Attenuation and Shadowing......Page 141
2.6.1.2. Multipath......Page 142
2.6.1.3. Delay......Page 145
2.6.1.4. Power Control......Page 146
2.6.1.5. Time-Varying User Population......Page 147
2.6.1.7. Non-Gaussian Ambient Noise......Page 148
2.6.2. System Issues......Page 149
2.6.2.2. Power Control......Page 150
2.6.2.4. Nonuniform Quality of Service......Page 151
2.6.2.6. Power Consumption......Page 153
References......Page 154
Acknowlegments......Page 162
3 Equalization of Multiuser channels......Page 163
3.1 Characterization of Wireless Channels......Page 165
3.2 Equalization of Known Multipath Fading Channels......Page 167
3.2.1 System Model......Page 169
3.2.2 Limits on Equalizer Performance over Fading Channels-Maximum Ukelihood Sequence Detection......Page 172
3.2.2.1 Sufficient Statistics for LTI Channels......Page 174
3.2.2.2 Sufficient Statistics for Additive White Gaussian Noise Channels......Page 175
3.2.3 The Matched-Filter Receiver for Time-Varying Channels......Page 177
3.2.4.1 AWGN Channel The Descorrelating Receiver......Page 178
3.2.5 Linear MMSE Equalization......Page 180
3.2.5.1 Linear Equalization for LTI Channels......Page 182
3.2.6 Successive Correlation and Detection-Feedback Equalizers for Multiple-Access Channels......Page 184
3.2.6.1 Decision-Feedback Equalization......Page 185
3.2.6.3 Decision-Feedback Equalizers for LTI Channels......Page 189
3.2.7 Chip-Rate, State-Space Approaches for Time-Varying Channels......Page 191
3.3 Blind Equalization in Multipath, slowly Time-Varying Channels......Page 193
3.3.1 The Fordward Link: Blind Equalization of Single-Input Multiple-Output FIR Channels......Page 194
3.3.1.1 The Cross-Relation Method......Page 196
3.3.1.2 Subspace-Based Methods......Page 200
3.3.1.3 Direct Symbol Estimation......Page 203
3.3.1.4 Issues in the Multiple FIR Channel Deconvolution Problem......Page 204
3.3.2 Blind Equalization in the Reverse Link via Multiple Observations......Page 206
3.3.2.1 Blind Equalization Using Multiple Antennas in CDMA Systems......Page 207
3.4 Concluding Remarks......Page 209
References......Page 210
Acknowledgements......Page 212