Single- and Multi-carrier Quadrature Amplitude Modulation: Principles and Applications for Personal Communications, WLANs and Broadcasting

L.Hanzo, W.T. Webb, T. Keller

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Contents

     Preface to the Second Edition xvii
1      Introduction and Background 2
1.1      Modulation methods 2
1.2      History of QAM 6
1.2.1      Determining the optimum constellation 6
1.2.1.1      Coherent and non-coherent reception 7
1.2.1.2      Clock recovery 7
1.2.1.3      The Type I, II and III constellations 8
1.2.2      Satellite links 11
1.2.2.1      Odd-bit constellations 11
1.2.3      QAM modem implementation 12
1.2.3.1      Non-linear amplification 13
1.2.3.2      Frequency selective fading and channel equalisers 13
1.2.3.3      Filtering 14
1.2.4      Advanced prototypes 14
1.2.5      QAM for mobile radio 15
1.3      Orthogonal Frequency Division Multiplexing based QAM 17
1.3.1      History of OFDM 17
1.3.2      Peak--to--mean power ratio 18
1.3.3      Synchronisation 19
1.3.4      OFDM / CDMA 19
1.3.5      Adaptive antennas 20
1.3.6      OFDM applications 20
1.4      Summary 20
1.5      Outline of Topics 21
2      Communications Channels 23
2.1      Fixed Communication Channels 23
2.1.1      Introduction 23
2.1.2      Fixed Channel Types 24
2.1.3      Characterisation of Noise 25
2.2      Telephone Channels 27
2.3      Mobile Radio Channels 30
2.3.1      Introduction 30
2.3.2      Equivalent Baseband and Passband Systems 31
2.3.3      Gaussian Mobile Radio Channel 36
2.3.4      Narrow-band fading Channels 38
2.3.4.1      Propagation Pathloss Law 39
2.3.4.2      Slow Fading Statistics 42
2.3.4.3      Fast Fading Statistics 42
2.3.4.4      Doppler Spectrum 47
2.3.4.5      Simulation of Narrowband Channels 48
2.3.4.5.1      Frequency-domain fading simulation 49
2.3.4.5.2      Time-domain fading simulation 50
2.3.4.5.3      Box-M\"uller Algorithm of AWGN generation 50
2.3.5      Wideband Channels 51
2.3.5.1      Modelling of Wideband Channels 51
2.4      Mobile Satellite Propagation 54
2.4.1      Fixed-link satellite channels 54
2.4.2      Satellite-to-mobile channels 54
2.5      Summary 56
3      Introduction to modems 57
3.1      Analogue to digital conversion 57
3.2      Mapping 59
3.3      Filtering 61
3.4      Modulation and demodulation 65
3.5      Data recovery 66
3.6      Summary 66
4      Basic QAM Techniques 69
4.1      Constellations for Gaussian channels 69
4.2      General Pulse-Shaping Techniques 72
4.2.1      Baseband Equivalent System 72
4.2.2      Nyquist Filtering 75
4.2.3      Raised-Cosine Nyquist Filtering 78
4.2.4      The Choice of Roll-off Factor 78
4.2.5      Optimum Transmit and Receive Filtering 79
4.2.6      Characterisation of ISI by Eye-Diagrams 81
4.2.7      Non-Linear Filtering 84
4.3      Methods of Generating QAM 85
4.3.1      Generating Conventional QAM 85
4.3.2      Superposed QAM 86
4.3.3      Offset QAM 87
4.3.4      Non-Linear Amplification 89
4.4      Methods of Detecting QAM Signals 90
4.4.1      Threshold Detection of QAM 90
4.4.2      Matched Filtered Detection 91
4.4.3      Correlation receiver 93
4.5      Linearisation of Power Amplifiers 95
4.5.1      The Linearisation Problem 95
4.5.2      Linearisation by Predistortion 96
4.5.2.1      The Predistortion Concept 96
4.5.2.2      Predistorter Description 96
4.5.2.3      Predistorter Coefficient Adjustment 101
4.5.2.4      Predistorter Performance 103
4.5.3      Postdistortion of NLA-QAM 105
4.5.3.1      The Postdistortion Concept 105
4.5.3.2      Postdistorter Description 106
4.5.3.3      Postdistorter Coefficient Adaptation 109
4.5.3.4      Postdistorter Performance 109
4.6      Non-differential coding for square QAM 110
4.7      Differential coding for square QAM 110
4.8      Summary 114
5      Square QAM 115
5.1      Decision Theory 115
5.2      QAM modulation and transmission 117
5.3      16-QAM Demodulation in AWGN 118
5.4      64-QAM Demodulation in AWGN 120
5.5      Summary 124
6      Clock and Carrier Recovery 125
6.1      Introduction 125
6.2      Clock Recovery 125
6.2.1      Times-two clock recovery 126
6.2.2      Early-late clock recovery 127
6.2.3      Zero crossing clock recovery 128
6.2.4      Synchroniser 129
6.3      Carrier Recovery 129
6.3.1      Times-n carrier recovery 132
6.3.2      Decision directed carrier recovery 134
6.3.2.1      Frequency and phase detection systems 137
6.4      Summary 142
7      Basic Equaliser Techniques 143
7.1      Introduction 143
7.2      Linear Equalisers 144
7.2.1      Zero-Forcing Equalisers 144
7.2.2      Least Mean-Squared Equalisers 148
7.2.3      Decision-Directed Adaptive Equalisers 151
7.3      Decision Feedback Equalisers 153
7.4      Fast Converging Equalisers 156
7.4.1      Least Squares Method 156
7.4.2      Recursive Least Squares Method~ 160
7.4.2.1      Cost-Function Weighting 160
7.4.2.2      Recursive Correlation Update 161
7.4.2.3      The Ricatti Equation of RLS Estimation 161
7.4.2.4      Recursive Equaliser Coefficient Update 162
7.5      Adaptive Equalisers for QAM 165
7.6      Viterbi Equalisers 167
7.6.1      Partial Response Modulation 167
7.6.2      Viterbi Equalisation 170
7.7      Summary 172
8      Trellis Coded Modulation 173
8.1      Introduction 173
8.2      TCM Fundamentals 174
8.3      8-PSK TCM 176
8.4      16-QAM TCM 181
8.5      TCM Under Phase Rotation 186
8.6      Summary 186
9      QAM Modems 189
9.1      Introduction 189
9.2      Transmission Bitrate Limits 190
9.3      V.29 Modem 191
9.3.1      Signal Constellation 191
9.3.2      Training Signals 193
9.3.3      Scrambling and Descrambling 197
9.3.4      Channel Equalisation and Synchronisation 198
9.4      V.32 Modem 198
9.4.1      General Features 198
9.4.2      Signal Constellation and Bit Mapping 198
9.4.2.1      Non-Redundant 16-QAM 198
9.4.2.2      Trellis-Coded 32-QAM 200
9.4.3      Scrambler and Descrambler 202
9.5      V.33 Modem 203
9.5.1      General Features 203
9.5.2      Signal Constellations and Bit Mapping 203
9.5.3      Synchronising Signals 205
9.6      Summary 206
10      Square QAM for fading channels 209
10.1      16-QAM Performance 209
10.2      64-QAM Performance 216
10.3      Reference Assisted Coherent QAM 218
10.3.1      Transparent Tone In Band Modulation 219
10.3.1.1      Introduction 219
10.3.1.2      Principles of TTIB 220
10.3.1.3      TTIB Subcarrier Recovery 223
10.3.1.4      TTIB Schemes Using Quadrature Mirror Filters 226
10.3.1.5      Residual Frequency Error Compensation~ 230
10.3.1.6      TTIB System Parameters~ 231
10.3.2      Pilot Symbol Assisted Modulation~ 233
10.3.2.1      Introduction 233
10.3.2.2      PSAM System Description 233
10.3.2.3      Channel Gain Estimation 235
10.3.2.4      PSAM Parameters 237
10.3.2.5      PSAM Performance 238
10.4      Summary 238
11      Star QAM 241
11.1      Introduction 241
11.2      Star QAM Transmissions 241
11.2.1      Differential coding 242
11.2.2      Differential decoding 243
11.2.3      Effect of oversampling\p@index {oversampling 243
11.2.4      Star 16-QAM Performance 245
11.3      Trellis coded modulation for QAM 247
11.4      Block Coding 248
11.5      64-level TCM 249
11.6      Bandwidth efficient coding results 251
11.7      Overall coding strategy 252
11.7.1      Square 16-QAM/PSAM/TCM Scheme 254
11.8      Distorted Constellation Star QAM 254
11.8.1      Introduction 254
11.8.2      Distortion of the Star 256
11.8.2.1      Amplitude Distortion 256
11.8.2.2      Phase Variations 258
11.9      Practical Considerations 261
11.9.1      Introduction 261
11.9.2      Hardware imperfections 261
11.9.2.1      Quantisation Levels 261
11.9.2.2      I-Q Crosstalk 264
11.9.2.3      Oversampling Ratio 264
11.9.2.4      AM-AM and AM-PM distortion 265
11.10      Summary 267
12      Timing Recovery for Mobile Radio 271
12.1      Introduction 271
12.2      Times-two clock recovery for QAM 271
12.3      Early-Late Clock Recovery 272
12.4      Modified Early-Late Clock Recovery 275
12.5      Clock Recovery in the Presence of ISI 277
12.5.1      Wideband Channel Models 277
12.5.2      Clock Recovery in Two-Path Channels 279
12.5.2.1      Case of $\tau \not =nT$ 279
12.5.2.2      Case of $\tau =nT$ 281
12.5.3      Clock Recovery Performance in Smeared ISI 281
12.6      Implementation Details 282
12.7      Carrier recovery 283
12.8      Summary 287
13      Variable Rate QAM 289
13.1      Introduction 289
13.2      Variable QAM Constellations 291
13.3      The RSSI Switching System 292
13.3.1      Results 295
13.4      The Error Detector Switching System 296
13.4.1      Results 299
13.5      Co-Channel Interference 301
13.6      Application to a DECT-Type System 303
13.7      Summary 305
14      Wideband QAM Transmissions 309
14.1      Introduction 309
14.2      The RAKE Combiner 309
14.3      The Proposed Equaliser 310
14.3.1      Linear Equaliser 310
14.3.2      Iterative Equaliser System 313
14.3.2.1      The One Symbol Window Equaliser 314
14.3.2.2      The Limited Correction DFE 317
14.3.3      Use of Error Correction Coding 319
14.4      Diversity in the wideband system 320
14.5      Summary 323
15      Quadrature-Quadrature AM 325
15.1      Introduction 325
15.2      Q$^2$PSK 325
15.3      Q$^2$AM 329
15.3.1      Square 16-QAM 329
15.3.2      Star 16-QAM 330
15.4      Spectral efficiency 332
15.5      Bandlimiting 16-Q$^2$AM 333
15.6      Results 334
15.7      Summary 338
16      Spectral Efficiency of QAM 341
16.1      Introduction 341
16.2      Efficiency in Large Cells 343
16.3      Spectrum Efficiency in Microcells 344
16.3.1      Microcellular Clusters 345
16.3.2      System Design for Microcells 348
16.3.3      Microcellular Radio Capacity 349
16.3.4      Modulation Schemes for Microcells 350
16.4      Summary 351
17      QAM Speech Systems 353
17.1      Introduction 353
17.2      Modem Schemes 354
17.2.1      GMSK Modulation 354
17.2.2      ${\begingroup \pi \endgroup \over 4 355
17.3      Speech Codecs 356
17.3.1      Adaptive Differential Pulse Code Modulation 356
17.3.2      Analysis-by-synthesis speech coding 358
17.3.2.1      The RPE-LTP Speech Encoder 358
17.3.2.2      The RPE-LTP Speech Decoder 361
17.4      Speech Quality Measures 363
17.5      Discontinuous Transmission 364
17.6      Channel Coding and Bit-mapping 365
17.7      Speech Transmission Systems 367
17.8      Packet Reservation Multiple Access 368
17.8.1      PRMA performance 370
17.9      Summary 371
18      Introduction to Orthogonal Frequency Division Multiplexing 373
18.1      Introduction 373
18.2      Principles of QAM-OFDM 376
18.3      Modulation by DFT 378
18.4      Transmission via Bandlimited Channels 382
18.5      Generalised Nyquist Criterion 384
18.6      Basic OFDM Modem Implementations 389
18.7      Cyclic OFDM Symbol Extension 391
18.8      Reducing MDI by Compensation 392
18.8.1      Transient System Analysis 392
18.8.2      Recursive MDI Compensation 394
18.9      Adaptive Channel Equalisation 396
18.10      OFDM Bandwidth Efficiency 397
18.11      Summary 398
19      OFDM Transmission over Gaussian channels 401
19.1      Orthogonal Frequency Division Multiplexing 402
19.1.1      History 402
19.1.1.1      Peak--to--mean power ratio 403
19.1.1.2      Synchronisation 403
19.1.1.3      OFDM / CDMA 404
19.1.1.4      Adaptive antennas 404
19.1.1.5      OFDM applications 404
19.2      The frequency domain modulation 405
19.3      OFDM system performance over AWGN Channels 405
19.4      Clipping amplification 406
19.4.1      OFDM signal amplitude statistics 406
19.4.2      Clipping amplifier simulations 407
19.4.2.1      Peak-power reduction techniques 408
19.4.2.2      BER performance using clipping amplifiers 409
19.4.2.3      Signal spectrum with clipping amplifier 410
19.4.3      Clipping Amplification -- Summary 413
19.5      Analog--to--Digital Conversion 413
19.6      Phase Noise 416
19.6.1      Effects of Phase Noise 416
19.6.2      Phase noise simulations 417
19.6.2.1      White phase noise model 417
19.6.2.1.1      Serial Modem 418
19.6.2.1.2      OFDM modem 419
19.6.2.2      Coloured phase noise model 421
19.6.3      Phase noise -- Summary 423
20      OFDM Transmission Over Wideband Channels 425
20.1      The channel model 425
20.1.1      The Wireless Asynchronous Transfer Mode system 426
20.1.1.1      The WATM Channel 426
20.1.1.2      The shortened WATM channel 428
20.1.2      The Wireless Local Area Network system 428
20.1.2.1      The WLAN channel 429
20.1.3      The UMTS system 429
20.1.3.1      The UMTS--type channel 430
20.2      Effects of time--dispersive channels on OFDM 431
20.2.1      Effects of the stationary time--dispersive channel 431
20.2.2      Non--stationary channel 431
20.2.2.1      Summary --- Time--Variant Channels 434
20.2.3      Signalling over time--dispersive OFDM channels 434
20.3      Channel Estimation 434
20.3.1      Frequency domain channel estimation 435
20.3.1.1      Pilot symbol assisted schemes 435
20.3.1.1.1      Linear interpolation for PSAM 435
20.3.1.1.2      Ideal lowpass interpolation for PSAM 439
20.3.1.1.3      Summary 440
20.3.2      Time domain channel estimation 442
20.4      System Performance 442
20.4.1      Static time dispersive channel 442
20.4.1.1      Perfect channel estimation 443
20.4.1.2      Differentially coded modulation 446
20.4.1.3      Pilot symbol assisted modulation 448
20.4.2      Slowly--varying time--dispersive channel 454
20.4.2.1      Perfect channel estimation 454
20.4.2.2      Pilot symbol assisted modulation 457
20.5      Conclusion 457
21      OFDM Time-- and Frequency--Domain Synchronisation 461
21.1      System performance with frequency-- and timing errors 461
21.1.1      Frequency shift 461
21.1.1.0.1      The spectrum of the OFDM signal 462
21.1.1.1      Effects of frequency mismatch on different modulation schemes 466
21.1.1.1.1      Coherent modulation 466
21.1.1.1.2      PSAM 467
21.1.1.1.3      Differential modulation 467
21.1.1.1.4      Frequency error -- summary 468
21.1.2      Time--domain synchronisation errors 469
21.1.2.1      Coherent modulation 469
21.1.2.2      Pilot symbol assisted modulation 469
21.1.2.3      Differential modulation 471
21.1.2.3.1      Time--domain synchronisation errors -- summary 473
21.2      Synchronisation algorithms 473
21.2.1      Coarse frame and OFDM symbol synchronisation 474
21.2.2      Fine symbol tracking 475
21.2.3      Frequency acquisition 475
21.2.4      Frequency tracking 475
21.2.5      Synchronisation by autocorrelation 476
21.2.6      Multiple Access Frame Structure 476
21.2.6.1      The Reference Symbol 476
21.2.6.2      The Correlation Functions 478
21.2.7      Frequency tracking and OFDM symbol synchronisation 479
21.2.7.1      OFDM symbol synchronisation 479
21.2.7.2      Frequency tracking 479
21.2.8      Frequency acquisition and frame synchronisation 482
21.2.8.1      Frame synchronisation 482
21.2.8.2      Frequency acquisition 483
21.2.8.3      Block diagram of the synchronisation algorithms 483
21.2.9      Synchronisation using Pilots 483
21.2.9.1      The reference symbol 484
21.2.9.2      Frequency Acquisition 484
21.2.9.4      Alternative frequency error estimation for frequency--domain pilot tones 491
21.3      Comparison of the Frequency Acquisition Algorithms 495
21.4      BER performance with frequency synchronisation 497
21.5      Conclusion 499
22      Adaptive OFDM Techniques 501
22.1      Introduction 501
22.1.1      Motivation 501
22.1.2      Adaptive techniques 502
22.1.2.1      Channel quality estimation 503
22.1.2.2      Parameter adaptation 504
22.1.2.3      Signalling the parameters 506
22.1.3      System aspects 506
22.2      Adaptive modulation for OFDM 506
22.2.1      System model 506
22.2.2      Channel model 508
22.2.3      Channel estimation 508
22.2.4      Choice of the modulation modes 509
22.2.4.1      Fixed threshold adaptation algorithm 509
22.2.4.2      Sub--band BER estimator adaptation algorithm 512
22.2.5      Constant throughput adaptive OFDM 513
22.2.6      Signalling and blind detection 515
22.2.6.1      Signalling 515
22.2.6.2      Blind detection by SNR estimation 516
22.2.6.3      Blind detection by multi--mode trellis decoder 518
22.2.7      Sub--band adaptive OFDM and channel coding 520
22.2.8      The effect of channel Doppler frequency 521
22.2.9      Channel estimation 524
22.3      Adaptive speech transmission system 526
22.3.1      Introduction 526
22.3.2      System overview 526
22.3.2.1      System parameters 527
22.3.3      Constant throughput adaptive modulation 528
22.3.3.1      Constant--rate BER performance 529
22.3.4      Multi--mode adaptation 531
22.3.4.1      Mode switching 531
22.3.5      Simulation results 532
22.3.5.1      Frame error results 532
22.3.5.2      Audio segmental SNR 534
22.4      Pre--Equalisation 536
22.4.1      Motivation 536
22.4.2      Perfect channel inversion 537
22.4.3      Limited dynamic range pre--equalisation 539
22.4.4      Pre--equalisation with sub--band blocking 540
22.4.5      Adaptive modulation with spectral pre--distortion 542
22.5      Comparison of the adaptive techniques 545
22.6      Near-optimum power- and bit-allocation in OFDM 547
22.6.1      State-of-the-art 547
22.6.2      Problem description 547
22.6.3      Power- and Bit-allocation Algorithm 549
22.6.4      Conclusions 552
22.7      Summary 552
23      Block--Coded Adaptive OFDM 555
23.1      Introduction 555
23.1.1      Motivation 555
23.1.2      Choice of error correction codes 556
23.2      Redundant Residue Number System Codes 556
23.2.1      Performance in AWGN channel 558
23.2.1.1      Performance in fading time--dispersive channel 559
23.2.1.2      Adaptive RRNS coded OFDM 560
23.2.2      ARRNS/AOFDM Transceivers 567
23.2.3      Soft decision RRNS decoding 567
23.3      Turbo BCH Codes 569
23.3.1      Adaptive TBCH coding 571
23.3.2      Joint ATBCH/AOFDM algorithm 572
23.4      Signalling 573
23.5      Comparison and Conclusions 574
24      QAM-based Video Broadcast Systems 577
24.1      DVB-T for Mobile Receivers 577
24.1.1      Background and Motivation 577
24.1.2      MPEG-2 Bit Error Sensitivity 578
24.1.3      DVB Terrestrial Scheme 589
24.1.4      Terrestrial Mobile Broadcast Channel Model 591
24.1.5      Data Partitioning Scheme 592
24.1.6      Performance of Data Partitioning Scheme 600
24.1.7      Non-hierarchical OFDM DVB Performance 608
24.1.8      Hierarchical OFDM DVB Performance 611
24.1.9      Conclusions and Future Work 616
24.2      Satellite-based Video Broadcasing 616
24.2.1      Background and Motivation 616
24.2.2      DVB Satellite Scheme 617
24.2.3      DVB-S Channel Model 618
24.2.4      The blind equalisers 619
24.2.5      Performance of the DVB Satellite Scheme 621
24.2.6      Conclusions and Future Work 633
A      Theoretical Performance of Various OFDM Synchronisation Algorithms 635
A.1      Frequency Synchronisation in an AWGN Channel 635
A.1.1      One phasor in AWGN environment 635
A.1.1.0.1      Cartesian coordinates 635
A.1.1.0.2      Polar coordinates 636
A.1.2      Product of two noisy phasors 636
A.1.2.0.3      Joint probability density 636
A.1.2.0.4      Phase distribution 637
A.1.2.0.5      Numerical integration 637
     Bibliography 641
     Index 669
     Author Index 678