Fundamentals of Wireless Communication
1
David Tse, University of California, Berkeley
Pramod Viswanath, University of Illinois, Urbana-Champaign
September 10, 2004
1
Draft, to be published by Cambridge University Press, which owns the copyright. Online
version is available with their permission. Comments will be much appreciated; please send
them to dtse@eecs.berkeley.edu or pramodv@uiuc.edu.
Contents
1 Introduct ion 12
1.1 Book Objective . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
1.2 Wireless Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
1.3 Book Outline . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
2 The Wireless Channel 21
2.1 Physical Modeling for Wireless Channels . . . . . . . . . . . . . . . . . 21
2.1.1 Free space, fixed transmitting and receive antennas . . . . . . . 23
2.1.2 Free space, moving antenna . . . . . . . . . . . . . . . . . . . . 24
2.1.3 Reflecting wall, fixed antenna . . . . . . . . . . . . . . . . . . . 25
2.1.4 Reflecting wall, moving antenna . . . . . . . . . . . . . . . . . . 27
2.1.5 Reflection from a Ground Plane . . . . . . . . . . . . . . . . . . 29
2.1.6 Power Decay with Distance and Shadowing . . . . . . . . . . . . 30
2.1.7 Moving Antenna, Multiple Reflectors . . . . . . . . . . . . . . . 31
2.2 Input/Output Model of the Wireless Channel . . . . . . . . . . . . . . 32
2.2.1 The Wireless Channel as a Linear Time-Varying System . . . . 32
2.2.2 Baseband Equivalent Model . . . . . . . . . . . . . . . . . . . . 34
2.2.3 A Discrete Time Baseband Model . . . . . . . . . . . . . . . . . 37
Discussion 2.1 Degrees of Freedom . . . . . . . . . . . . . . . 40
2.2.4 Additive White Noise . . . . . . . . . . . . . . . . . . . . . . . . 41
2.3 Time and Frequency Coherence . . . . . . . . . . . . . . . . . . . . . . 42
2.3.1 Doppler Spread and Coherence Time . . . . . . . . . . . . . . . 42
2.3.2 Delay Spread and Coherence Bandwidth . . . . . . . . . . . . . 44
2.4 Statistical Channel Models . . . . . . . . . . . . . . . . . . . . . . . . . 47
2.4.1 Modeling Philosophy . . . . . . . . . . . . . . . . . . . . . . . . 47
2.4.2 Rayleigh and Rician Fading . . . . . . . . . . . . . . . . . . . . 48
2.4.3 Tap Ga in Autocorrelation Function . . . . . . . . . . . . . . . . 50
Example 2.2 Clarke’s Model . . . . . . . . . . . . . . . . . . . 51
2.5 Bibliographical Notes . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
2.6 Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
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3 Point-to-Point C ommunication:
Detection, Diversity and Channel Uncertainty 64
3.1 Detection in a Rayleigh Fading Channel . . . . . . . . . . . . . . . . . 65
3.1.1 Noncoherent Detection . . . . . . . . . . . . . . . . . . . . . . . 65
3.1.2 Coherent Detection . . . . . . . . . . . . . . . . . . . . . . . . . 68
3.1.3 Fro m BPSK to QPSK: Exploiting the Degrees of Freedom . . . 72
3.1.4 Diversity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76
3.2 Time Diversity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76
3.2.1 Repetition Coding . . . . . . . . . . . . . . . . . . . . . . . . . 78
3.2.2 Beyond Repetition Coding . . . . . . . . . . . . . . . . . . . . . 80
Example 3.1 Time Diversity in G SM . . . . . . . . . . . . . . 86
3.3 Antenna Diversity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88
3.3.1 Receive Diversity . . . . . . . . . . . . . . . . . . . . . . . . . . 89
3.3.2 Transmit Diversity: Space-Time Codes . . . . . . . . . . . . . . 90
3.3.3 MIMO: A 2 × 2 Example . . . . . . . . . . . . . . . . . . . . . . 94
3.4 Frequency Diversity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100
3.4.1 Basic Concept . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100
3.4.2 Single-Carrier with ISI Equalization . . . . . . . . . . . . . . . . 102
3.4.3 Direct Sequence Spread Spectrum . . . . . . . . . . . . . . . . . 109
3.4.4 Orthogonal Frequency Division Multiplexing . . . . . . . . . . . 114
3.5 Impact of Channel Uncertainty . . . . . . . . . . . . . . . . . . . . . . 122
3.5.1 Noncoherent Detection for DS Spread Spectrum . . . . . . . . . 122
3.5.2 Channel Estimation . . . . . . . . . . . . . . . . . . . . . . . . . 125
3.5.3 Other Diversity Scenarios . . . . . . . . . . . . . . . . . . . . . 127
3.6 Bibliographical Notes . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131
3.7 Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 32
4 Cellular Systems: Multiple Access and Interference Management 143
4.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143
4.2 Narrowband Cellular Systems . . . . . . . . . . . . . . . . . . . . . . . 146
4.2.1 Narrowband allocations: GSM system . . . . . . . . . . . . . . 147
4.2.2 Impact on Network and System Design . . . . . . . . . . . . . . 1 50
4.2.3 Impact on Frequency Reuse . . . . . . . . . . . . . . . . . . . . 151
4.3 Wideband Systems: CDMA . . . . . . . . . . . . . . . . . . . . . . . . 152
4.3.1 CDMA Uplink . . . . . . . . . . . . . . . . . . . . . . . . . . . 155
4.3.2 CDMA Downlink . . . . . . . . . . . . . . . . . . . . . . . . . . 170
4.3.3 System Issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171
4.4 Wideband Systems: OFDM . . . . . . . . . . . . . . . . . . . . . . . . 174
4.4.1 Allocation Design Principles . . . . . . . . . . . . . . . . . . . . 174
4.4.2 Hopping Pattern . . . . . . . . . . . . . . . . . . . . . . . . . . 175
4.4.3 Signal Characteristics and Receiver Design . . . . . . . . . . . . 177
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4.4.4 Sectorization . . . . . . . . . . . . . . . . . . . . . . . . . . . . 178
Example 4.1 Flash-OFDM . . . . . . . . . . . . . . . . . . . . 179
4.5 Bibliographical Notes . . . . . . . . . . . . . . . . . . . . . . . . . . . . 181
4.6 Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 82
5 Capacity of Wireless Channels 195
5.1 AWGN Channel Capacity . . . . . . . . . . . . . . . . . . . . . . . . . 196
5.1.1 Repetition Coding . . . . . . . . . . . . . . . . . . . . . . . . . 196
5.1.2 Packing Spheres . . . . . . . . . . . . . . . . . . . . . . . . . . . 197
Discussion 5.1 Capacity-Achieving AWGN Channel Codes . . 199
5.2 Resources of the AWGN Channel . . . . . . . . . . . . . . . . . . . . . 201
5.2.1 Continuous-Time AWGN Channel . . . . . . . . . . . . . . . . . 202
5.2.2 Power and Bandwidth . . . . . . . . . . . . . . . . . . . . . . . 2 02
Example 5.2 Bandwidth Reuse in Cellular Systems . . . . . . 205
5.3 Linear Time-Invariant Gaussian Channels . . . . . . . . . . . . . . . . 209
5.3.1 Single Input Multiple Output (SIMO) Channel . . . . . . . . . 209
5.3.2 Multiple Input Single Output (MISO) Channel . . . . . . . . . 210
5.3.3 Frequency-Selective Channel . . . . . . . . . . . . . . . . . . . . 211
5.4 Capacity of Fading Channels . . . . . . . . . . . . . . . . . . . . . . . . 217
5.4.1 Slow Fading Channel . . . . . . . . . . . . . . . . . . . . . . . . 218
5.4.2 Receive Diversity . . . . . . . . . . . . . . . . . . . . . . . . . . 2 21
5.4.3 Transmit Diversity . . . . . . . . . . . . . . . . . . . . . . . . . 222
5.4.4 Time and Frequency Diversity . . . . . . . . . . . . . . . . . . . 227
5.4.5 Fa st Fading Channel . . . . . . . . . . . . . . . . . . . . . . . . 231
5.4.6 Transmitter Side Information . . . . . . . . . . . . . . . . . . . 236
Example 5.3 Rate Adaptation in IS-856 . . . . . . . . . . . . . 244
5.4.7 Frequency-Selective Fading Channels . . . . . . . . . . . . . . . 247
5.4.8 Summary: A Shift in Point of View . . . . . . . . . . . . . . . . 248
5.5 Bibliographical Notes . . . . . . . . . . . . . . . . . . . . . . . . . . . . 252
5.6 Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 53
6 Multiuser Capacity and Opportunistic Communication 266
6.1 Uplink AWGN Channel . . . . . . . . . . . . . . . . . . . . . . . . . . 267
6.1.1 Capacity via Successive Interference Cancellation . . . . . . . . 267
6.1.2 Comparison with Conventional CDMA . . . . . . . . . . . . . . 271
6.1.3 Comparison with Orthogonal Multiple Access . . . . . . . . . . 271
6.1.4 General K-user Uplink Capacity . . . . . . . . . . . . . . . . . . 273
6.2 Downlink AWGN Channel . . . . . . . . . . . . . . . . . . . . . . . . . 275
6.2.1 Symmetric Case: Two Capacity-Achieving Schemes . . . . . . . 276
6.2.2 General Case: Superposition Coding Achieves Capacity . . . . . 279
Discussion 6.1 SIC: Implementation Issues . . . . . . . . . . . 2 83
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6.3 Uplink Fading Channel . . . . . . . . . . . . . . . . . . . . . . . . . . . 285
6.3.1 Slow Fading Channel . . . . . . . . . . . . . . . . . . . . . . . . 285
6.3.2 Fa st Fading Channel . . . . . . . . . . . . . . . . . . . . . . . . 287
6.3.3 Full Channel Side Information . . . . . . . . . . . . . . . . . . . 289
6.4 Downlink Fading Channel . . . . . . . . . . . . . . . . . . . . . . . . . 2 92
6.4.1 Channel Side Information at Receiver Only . . . . . . . . . . . . 293
6.4.2 Full Channel Side Information . . . . . . . . . . . . . . . . . . . 294
6.5 Frequency-Selective Fading Channels . . . . . . . . . . . . . . . . . . . 294
6.6 Multiuser Diversity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 295
6.6.1 Multiuser Diversity Gain . . . . . . . . . . . . . . . . . . . . . . 295
6.6.2 Multiuser versus Classical Diversity . . . . . . . . . . . . . . . . 298
6.7 Multiuser Diversity: System Aspects . . . . . . . . . . . . . . . . . . . 300
6.7.1 Fa ir Scheduling and Multiuser Diversity . . . . . . . . . . . . . 301
6.7.2 Channel Prediction and Feedback . . . . . . . . . . . . . . . . . 308
6.7.3 Opportunistic Beamforming using Dumb Antennas . . . . . . . 309
6.7.4 Multiuser Diversity in Multi-cell Systems . . . . . . . . . . . . . 318
6.7.5 A System View . . . . . . . . . . . . . . . . . . . . . . . . . . . 319
6.8 Bibliographical Notes . . . . . . . . . . . . . . . . . . . . . . . . . . . . 325
6.9 Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 26
7 MIMO I: Spatial Multiplexing and Channel Modeling 342
7.1 Multiplexing Capability of Deterministic MIMO Channels . . . . . . . 343
7.1.1 Capacity via Singular Value Decomposition . . . . . . . . . . . 343
7.1.2 Rank and Condition Number . . . . . . . . . . . . . . . . . . . 346
7.2 Physical Modeling of MIMO Channels . . . . . . . . . . . . . . . . . . 347
7.2.1 Line-of-Sight SIMO channel . . . . . . . . . . . . . . . . . . . . 348
7.2.2 Line-of-Sight MISO Channel . . . . . . . . . . . . . . . . . . . . 350
7.2.3 Antenna arrays with only a line-of-sight path . . . . . . . . . . 351
7.2.4 Geographically separated antennas . . . . . . . . . . . . . . . . 352
7.2.5 Line-of-sight plus one reflected path . . . . . . . . . . . . . . . . 359
7.3 Modeling of MIMO Fading Channels . . . . . . . . . . . . . . . . . . . 364
7.3.1 Basic Approach . . . . . . . . . . . . . . . . . . . . . . . . . . . 364
7.3.2 MIMO Multipath Channel . . . . . . . . . . . . . . . . . . . . . 365
7.3.3 Angular Domain Representat io n of Signals . . . . . . . . . . . . 367
7.3.4 Angular Domain Representat io n of MIMO Channels . . . . . . . 370
7.3.5 Statistical Modeling in the Angular Domain . . . . . . . . . . . 372
7.3.6 Degrees of Freedom and Diversity . . . . . . . . . . . . . . . . . 372
Example 7.1 Degrees of Freedom in Clustered Response Models 375
7.3.7 Dependency on Antenna Spacing . . . . . . . . . . . . . . . . . 380
7.3.8 I.I.D. Rayleigh Fading Model . . . . . . . . . . . . . . . . . . . 387
7.4 Bibliographical Notes . . . . . . . . . . . . . . . . . . . . . . . . . . . . 390
