Mobile Radio Communications

R. Steele (Editor)

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Contents

1      Introduction to Digital Cellular Radio 1
1.1      The Background to Digital Cellular Mobile Radio 1
1.2      Mobile Radio Propagation 3
1.2.1      Gaussian Channel 5
1.2.2      Rayleigh Fading Channel 5
1.2.3      Rician Channel 12
1.2.4      Wideband Channels 15
1.2.4.1      GSM Wideband Channels 19
1.2.4.2      The Two-ray Rayleigh Fading Channel 21
1.2.4.3      Real Channel Impulse Responses 22
1.2.5      Path Loss 23
1.2.6      Propagation in Microcells for Highways and City Streets 24
1.2.7      Indoor Radio Propagation 34
1.2.7.1      60 GHz Propagation 40
1.3      Principles of Multiple Access Communications 42
1.4      First Generation Mobile Radio Systems 51
1.4.1      Network Aspects 54
1.4.1.1      Control Channels 57
1.5      Digital Cellular Mobile Radio Systems 61
1.5.1      Communication Sub-systems 61
1.5.2      FDMA Digital Link 65
1.5.3      TDMA Digital Link 68
1.6      Second Generation Cellular Mobile Systems 70
1.6.1      Qualcomm CDMA 71
1.7      Cordless Telecommunications 76
1.7.1      CT2 System 77
1.7.2      Digital European Cordless Telecommunications (DECT) Systems 79
1.7.3      Parameters of CTs and Cellular Systems 81
1.8      Teletraffic Considerations 83
2      Mobile Radio Channels 92
2.1      Complex Baseband Representation 93
2.1.1      Bandpass Signals 93
2.1.2      Linear Bandpass Systems 97
2.1.3      Response of a Linear Bandpass System 99
2.1.4      Noise in Bandpass Systems 101
2.2      Mobile Radio Channel Types 103
2.2.1      The Propagation Channel 103
2.2.2      The Radio Channel 104
2.2.3      The Modulation Channel 104
2.2.4      The Digital Channel 105
2.2.5      A Channel Naming Convention 105
2.3      Physical Description of the Channels 106
2.3.1      The Propagation Channel 106
2.3.1.1      The Received Signal 106
2.3.1.2      The Impulse Response of the Channel 108
2.3.1.3      The Effect of Time Variations on the Channel 109
2.3.1.4      Channel Effects on Systems of Finite Delay Resolution 111
2.3.1.5      Channel Effects on Systems of Finite Doppler Resolution 115
2.3.2      The Radio Channel 116
2.3.3      The Modulation Channel 118
2.3.4      The Digital Channel 119
2.4      Classification of Channels 119
2.4.1      Time Dispersion and Frequency-Selective Fading 119
2.4.2      Frequency Dispersion and Time-Selective Fading 123
2.4.3      Channel Classifications 124
2.5      Linear Time-Variant Channels 127
2.5.1      The Variables Used For System Characterisation 127
2.5.2      The Bello System Functions 128
2.5.3      Description of Randomly Time-Variant Channels 136
2.5.3.1      Autocorrelation of a Bandpass Stochastic Process 136
2.5.3.2      General Randomly Time-Variant Channels 141
2.5.3.3      Wide-Sense Stationary Channels 142
2.5.3.4      Uncorrelated Scattering Channels 144
2.5.3.5      Wide-Sense Stationary Uncorrelated Scattering \newline Channels 147
2.5.3.6      Quasi-Wide-Sense Stationary Uncorrelated Scattering \newline Channels 148
2.6      Characterisation by Bello Functions 148
2.6.1      Space-variance 149
2.6.2      Statistical Characteristics 150
2.6.3      Small-Area Characterisation 151
2.6.4      Large-Area Characterisation 152
2.7      Practical Channel Description 153
2.7.1      Propagation Pathloss Law 155
2.7.1.1      The Hata Pathloss Models 157
2.7.2      Slow Fading Statistics 163
2.7.3      Fast Fading Evaluation 163
2.7.3.1      Analysis of Fast Fading Statistics 163
2.7.3.2      The Relation of Rician and Gaussian PDFs 169
2.7.3.3      Extracting Fast Fading Characteristics 170
2.7.3.4      Goodness-of-fit Techniques 173
2.7.3.4.1      Chi-square Goodness-of-fit Test 173
2.7.3.4.2      Kolmogorov-Smirnov (KS) Goodness-of-fit Test 174
2.7.3.4.3      Goodness-of-fit of the Hypothesis Distribution 175
2.7.4      Summary 177
3      Speech Coding 186
3.1      Introduction 186
3.2      Waveform Encoding Techniques 187
3.3      Embedded Delta Modulation 191
3.3.1      Theory of EDM 192
3.3.2      Performance of EDM 196
3.4      Sub-band Coding 198
3.4.1      Theory of Quadrature Mirror Filtering 200
3.4.2      The SBC Algorithm 206
3.4.2.1      QMF Filter Bank 209
3.4.2.2      Quantization 210
3.4.2.3      Semi-adaptive Bit Allocation 213
3.4.3      Simulation Results 215
3.4.4      Increasing the Robustness of SBC to Channel Errors 215
3.4.5      Codec Performance in Acoustic Environments 221
3.4.6      SBC Performance over Rayleigh and Gaussian Channels 223
3.5      Analysis-by-synthesis predictive coding 226
3.5.1      General model for analysis-by-synthesis speech coding 227
3.5.1.1      The short-term predictor 229
3.5.1.1.1      The Autocorrelation Method 231
3.5.1.1.2      The Covariance Method 233
3.5.1.1.3      Considerations in the Choice of LPC Analysis Conditions 235
3.5.1.1.4      Quantization of the LPC parameters 237
3.5.1.1.4.1      Reflection Coefficients 239
3.5.1.1.4.2      Line Spectrum Pairs 241
3.5.1.1.4.3      Interpolation of LPC parameters 245
3.5.1.2      The Long-Term Predictor (LTP) 246
3.5.1.2.1      Computing the LTP parameters inside the loop: the adaptive codebook approach 249
3.5.1.2.2      Quantization of LTP parameters 255
3.5.1.3      The Error Weighting Filter 256
3.5.2      Multi-pulse and Regular-pulse Excitation 259
3.5.2.1      Formulation of the pulse amplitudes and positions computation 259
3.5.2.2      The Multi-pulse Approach 264
3.5.2.3      Modification of the MPE Algorithm 267
3.5.2.4      Evaluation of the Multi-pulse Algorithm 270
3.5.2.4.1      Number of pulses per excitation frame 271
3.5.2.4.2      The length of the excitation frame 273
3.5.2.5      Regular Pulse Excitation Approach (RPE) 275
3.5.2.6      Evaluation of the RPE Algorithm 276
3.5.2.6.1      Pulse spacing 276
3.5.2.6.2      Excitation search frame length 279
3.5.2.7      Simplification of the RPE Algorithm 280
3.5.2.7.1      The autocorrelation approach 281
3.5.2.7.2      Eliminating the matrix inversion 281
3.5.2.8      Quantization of the excitation in MPE and RPE coders 288
3.5.3      Code-Excited Linear Prediction (CELP) 295
3.5.3.1      CELP Principle 297
3.5.3.2      Simplification of the CELP Search Procedure Using the Autocorrelation Approach 302
3.5.3.3      Using Structured Codebooks 303
3.5.3.3.1      Sparse Excitation Codebooks 304
3.5.3.3.2      Ternary Codebooks 305
3.5.3.3.3      Algebraic codebooks 307
3.5.3.3.4      Overlapping Codebooks 308
3.5.3.3.5      Self Excitation 312
3.5.3.4      CELP performance 312
3.5.4      Binary Pulse Excitation 317
3.5.4.1      Transformed Binary Pulse Excitation 317
3.5.4.2      Excitation Determination 321
3.5.4.2.1      Efficient Exhaustive Search: The Gray Code Approach 323
3.5.4.2.2      Non-exhaustive Search 324
3.5.4.3      Evaluation of the BPE Coder 326
3.5.4.4      Complexity Comparison between BPE and CELP 331
3.5.5      Postfiltering 333
4      Channel Coding 347
4.1      Introduction 347
4.2      Interleaving Techniques 348
4.2.1      Diagonal Interleaving 349
4.2.2      Block Interleaving 350
4.2.3      Inter-Block Interleaving 352
4.2.4      Convolutional Interleaving 353
4.2.5      Discrete Memoryless Channel 354
4.2.6      The Effect of Interleaving on Symbol Error Distribution 355
4.2.7      Effect of Symbol Size on Symbol Error Probability 357
4.3      Convolutional Codes 358
4.3.1      Convolutional Encoding 358
4.3.2      State and Trellis Diagrams 361
4.3.3      Maximum Likelihood Decoding 366
4.3.3.1      Hard-decision Decoding 366
4.3.3.1.1      Correct Decoding 368
4.3.3.1.2      Incorrect Decoding 368
4.3.3.2      Soft-decision Decoding 369
4.3.3.3      The Viterbi Algorithm 371
4.3.4      Distance Properties of Convolutional Codes 375
4.3.5      Punctured Convolutional Codes 381
4.3.6      Hard-decision Decoding Theory 385
4.3.7      Soft-decision Decoding Theory 387
4.3.8      Convolutional Code Performance 389
4.3.8.1      Convolutional Code Performance via Gaussian Channels 390
4.3.8.2      Convolutional Code Performance via Rayleigh Channels 392
4.3.9      Conclusions on Convolutional Coding 398
4.4      Block Codes 399
4.4.1      The Structure of Block Codes 401
4.4.1.1      Finite Fields 401
4.4.1.2      Vector Spaces 403
4.4.1.3      Extension Fields 406
4.4.1.4      Primitive Polynomials 408
4.4.1.5      Minimal Polynomials 412
4.4.2      Cyclic Codes 416
4.4.3      BCH Codes 419
4.4.3.1      Binary $BCH$ Codes 421
4.4.3.2      Nonbinary $BCH$ Codes 422
4.4.3.2.1      Reed-Solomon Codes 423
4.4.4      Encoding of Block Codes 424
4.4.4.1      Binary $BCH$ Encoder 426
4.4.4.2      Reed-Solomon Encoder 428
4.4.5      Decoding Algorithms for Block Codes 431
4.4.5.1      The Syndrome Equations 431
4.4.5.2      Peterson-Gorenstein-Zierler Decoding 433
4.4.5.3      Berlekamp-Massey Algorithm 439
4.4.5.4      Forney Algorithm 447
4.4.6      Trellis Decoding for Block Codes 452
4.4.6.1      Trellis Construction 452
4.4.6.2      Trellis Decoding 453
4.4.7      Block Decoding Theory 455
4.4.7.1      Probability of Correct Decoding 456
4.4.7.2      Probability of Incorrect Decoding 457
4.4.7.2.1      Number of Weight-$h$ Codewords 461
4.4.7.3      Post-decoding Bit and Symbol Error Probabilities 462
4.4.8      Block Coding Performance 463
4.4.8.1      Block Coding Performance via Gaussian Channels 463
4.4.8.2      Block Coding Performance via Rayleigh Fading Channels 467
4.4.8.3      Soft/Hard Decisions via Gaussian Channels 473
4.4.9      Conclusions on Block Coding 475
4.5      Concatenated Codes 476
4.5.1      Nested Codes 477
4.5.2      Product Codes 479
4.6      Comparison of Error Control Codes 480
5      Quaternary Frequency Shift Keying 489
5.1      An S900-D Like System 489
5.2      QFSK Trans\discretionary -
5.2.1      Demodulation in the Ab\discretionary -
5.2.1.1      Coherent Demodulation 499
5.2.1.2      Non-coherent Demodulation 503
5.2.2      Single Cochannel Interferer with Non-coherent Demodulation 510
5.2.3      Multiple Cochannel Interferers 513
5.2.3.1      Coherent Demodulation 514
5.2.3.2      Non-Coherent Demodulation 515
5.3      QFSK Transmission Over Rayleigh Channels 517
5.3.1      Coherent Demodulation 519
5.3.2      Non-Coherent Demodulation 520
5.4      Conclusions 521
6      Wideband Systems 523
6.1      Generalised Phase Modulation 523
6.1.1      Digital Phase Modulation 524
6.1.2      Digital Frequency Modulation 529
6.1.3      Power Spectra 539
6.1.3.1      Modulated Signal Power Spectral Density Estimation 541
6.1.4      TDMA Format for DPM and DFM Transmissions 542
6.1.5      Hardware Aspects 543
6.2      CPM Receivers 544
6.2.1      Optimal Receiver 545
6.2.2      Probability of Symbol Error 549
6.2.3      Principle of Viterbi Equalisation 552
6.2.4      RF to Baseband Conversion 558
6.2.5      Baseband Processing 561
6.2.6      Viterbi Equalisation of Digital Phase Modulation 575
6.2.7      Viterbi Equalisation of GMSK Signals 582
6.2.8      Simulations of DPM Transmissions 587
6.2.9      Simulations of GMSK Transmissions 595
7      Frequency Hopping 601
7.1      Introduction 601
7.2      Principles of SFHMA 602
7.2.1      SFHMA Protocols 603
7.2.2      Reuse Cellular Structures 604
7.2.3      Propagation Factors 608
7.3      Description of an SFHMA System 612
7.3.1      Multiple Access Protocol 612
7.3.2      Time Division Multiplexing 613
7.3.3      Modulation and Equalization 613
7.3.4      Speech and Channel Coding 613
7.3.5      Transmitted Signal Structure 614
7.3.6      Frequency Reuse 615
7.4      BER Performance 615
7.4.1      BER Performance of the MLSE Detector 616
7.4.2      BER Performance of the MSK-Type Detector 618
7.4.3      Channel Models and System Assumptions 622
7.4.4      BER Analysis of SFHMA System in a Static AWGN Channel 626
7.4.5      BER Analysis in a Rayleigh Fading AWGN Channel 629
7.5      BER Performance 632
7.5.1      BER Analysis in a Noiseless Static Channel 633
7.5.2      BER Analysis in a Static AWGN Channel 635
7.5.3      BER Analysis in a Rayleigh Fading AWGN Channel 640
7.5.4      BER Analysis of a Noiseless Rayleigh Fading Channel 642
7.6      Estimation of Spectral Efficiency 644
7.6.1      Spectral Efficiency of SFHMA System : Method A 647
7.6.2      Spectral Efficiency of SFHMA System : Method B 660
7.6.3      Spectral efficiency of TD/FDMA system. 666
7.7      Conclusions 671
7.8      Appendix A: 672
8      The GSM System 677
8.1      Introduction 677
8.2      Overview of the GSM System 680
8.3      Mapping Logical Channels 683
8.3.1      Logical Channels 683
8.3.2      Physical Channels 686
8.3.2.1      Mapping the TCH/FS and its SACCH as well as FACCH onto Physical Channels 686
8.3.2.2      Mapping Broadcast and Common Control Channels onto Physical Channels 691
8.3.2.3      Broadcast Control Channel Messages 695
8.3.3      Carrier and Burst Synchronisation 696
8.3.4      Frequency Hopping 698
8.4      Speech Coding 700
8.4.1      Candidate codecs 700
8.4.2      The RPE-LTP Speech encoder 701
8.4.3      The RPE-LTP Speech Decoder 705
8.5      Channel Coding and Interleaving 707
8.5.1      FEC for Speech Channels 707
8.5.2      FEC for Data Channels 712
8.5.2.1      Low-Rate Data Transmission 714
8.5.3      FEC in Control Channels 715
8.5.4      FEC performance 718
8.6      Transmission and Re\discretionary -
8.7      Wideband Channels and Viterbi Equalisation 727
8.7.1      Channel Models 727
8.7.2      Viterbi Equaliser 729
8.7.3      Performance 732
8.8      Radio Link Control 736
8.8.1      Link Control Concept 736
8.8.2      A Link Control Algorithm 740
8.8.2.1      BS preprocessing and averaging 740
8.8.2.2      RF power control and HO initiation 740
8.8.2.3      Decision algorithm 744
8.8.2.4      HO decisions in the MSC 745
8.8.2.5      Handover scenarios 745
8.9      Discontinuous Transmission 747
8.9.1      DTX Concept 747
8.9.2      Voice Activity Detection 748
8.9.3      DTX Transmitter Functions 752
8.9.4      DTX Receiver Functions 753
8.9.5      Comfort Noise Insertion and Speech/Noise Extrapolation 756
8.10      Ciphering 756
8.11      Telecommunication Services 759
     Glossary 768