数字通信(英文版.第3版)

.1.7 advantages of digital communications, 15
1.8 summary, 16
part one signals and systems theory, 19
2 periodic and transient signals, 21
2.1 introduction, 21
2.2 periodic signals, 22
2.2.1 sinusoids, cisoids and phasors, 22
2.2.2 fourier series, 27
2.2.3 conditions for existence, convergence and gibb’s phenomenon, 41
2.2.4 bandwidth, rates of change, sampling and aliasing, 44
2.3 transient signals, 47
2.3.1 fourier transforms, 47
2.3.2 practical calculation of fourier transforms, 49
xxxiv contents
2.3.3 fourier transform pairs, 51
2.3.4 fourier transform theorems and convolution, 56
2.4 power and energy spectra, 65
2.5 generalised orthogonal function expansions, 67
2.5.1 review of vectors, 67
2.5.2 vector interpretation of waveforms, 70
2.5.3 orthogonal and orthonormal signals, 72
2.5.4 evaluation of basis function coefficients, 74
2.5.5 error energy and completeness, 75
2.6 correlation functions, 77
2.7 summary, 83
2.8 problems, 84
3 random signals and noise, 86
3.1 introduction, 86
3.2 probability theory, 86
3.2.1 conditional probabilities, joint probabilities and bayes’s rule, 88
3.2.2 statistical independence, 89
3.2.3 discrete probability of errors in a data block, 90
3.2.4 cumulative distributions and probability density functions, 92
3.2.5 moments, percentiles and modes, 96
3.2.6 joint and marginal pdfs, correlation and covariance, 101
3.2.7 joint moments, correlation and covariance, 104
3.2.8 joint gaussian random variables, 107
3.2.9 addition of random variables and the central limit theorem, 108
3.3 random processes, 112
3.3.1 stationarity and ergodicity, 114
3.3.2 strict and loose sense gaussian processes, 115
3.3.3 autocorrelation and power spectral density, 117
3.3.4 signal memory, decorrelation time and white noise, 121
3.3.5 cross correlation of random processes, 122
3.4 summary, 122
3.5 problems, 124
4 linear systems, 128
4.1 introduction, 128
4.2 linear systems, 128
4.2.1 properties of linear systems, 129
4.2.2 importance of linear systems, 130
4.3 time domain description of linear systems, 133
4.3.1 linear differential equations, 133
4.3.2 discrete signals and matrix algebra, 134
4.3.3 continuous signals, convolution and impulse response, 134
4.3.4 physical interpretation of y(t) = h(t) x(t), 136
4.3.5 step response, 138
4.4 frequency domain description, 141
4.5 causality and the hilbert transform, 144
contents xxxv
4.6 random signals and linear systems, 147
4.6.1 power spectral densities and linear systems, 147
4.6.2 noise bandwidth, 149
4.6.3 pdf of filtered noise, 149
4.6.4 spectrum analysers, 151
4.7 non-linear systems and transformation of random variables, 152
4.7.1 rayleigh pdf, 153
4.7.2 chi-square distributions, 155
4.8 summary, 157
4.9 problems, 157
part two digital communications principles, 161
5 sampling, multiplexing and pcm, 163
5.1 introduction, 163
5.2 pulse modulation, 163
5.3 sampling, 165
5.3.1 natural and flat topped sampling, 166
5.3.2 baseband sampling and nyquist’s criterion, 167
5.3.3 aliasing, 168
5.3.4 practical sampling, reconstruction and signal to distortion ratio, 169
5.3.5 bandpass sampling, 173
5.4 analogue pulse multiplexing, 176
5.5 quantised pam, 179
5.6 signal to quantisation noise ratio (snqr), 181
5.7 pulse code modulation, 183
5.7.1 snqr for linear pcm, 183
5.7.2 snr for decoded pcm, 185
5.7.3 companded pcm, 188
5.7.4 pcm multiplexing, 191
5.8 bandwidth reduction techniques, 192
5.8.1 delta pcm, 193
5.8.2 differential pcm, 193
5.8.3 adaptive dpcm, 195
5.8.4 delta modulation, 196
5.8.5 adaptive delta modulation, 199
5.9 summary, 201
5.10 problems, 202
6 baseband transmission and line coding, 204
6.1 introduction, 204
6.2 baseband centre point detection, 204
6.2.1 baseband binary error rates in gaussian noise, 205
6.2.2 multilevel baseband signalling, 209
6.3 error accumulation over multiple hops, 211
xxxvi contents
6.4 line coding, 214
6.4.1 unipolar signalling, 217
6.4.2 polar signalling, 219
6.4.3 dipolar signalling, 219
6.4.4 bipolar alternate mark inversion signalling, 219
6.4.5 pulse synchronisation and hdbn coding, 220
6.4.6 coded mark inversion (cmi), 220
6.4.7 nbmt coding, 220
6.5 multiplex telephony, 221
6.6 digital signal regeneration, 222
6.6.1 pcm line codes, 223
6.6.2 equalisation, 224
6.6.3 eye diagrams, 226
6.6.4 crosstalk, 228
6.7 symbol timing recovery (str), 230
6.8 repeater design, 232
6.9 digital transmission in local loop, 232
6.10 summary, 236
6.11 problems, 236
7 decision theory, 238
7.1 introduction, 238
7.2 a priori, conditional and a posteriori probabilities, 239
7.3 symbol transition matrix, 240
7.3.1 binary symmetric channel, 240
7.4 bayes’s decision criterion, 243
7.4.1 decision costs, 243
7.4.2 expected conditional decision costs, 243
7.4.3 optimum decision rule, 244
7.4.4 optimum decision threshold voltage, 245
7.4.5 average unconditional decision cost, 246
7.5 neyman–pearson decision criterion, 249
7.6 summary, 250
7.7 problems, 251
8 optimum filtering for transmission and reception, 253
8.1 introduction, 253
8.2 pulse shaping for optimum transmissions, 253
8.2.1 intersymbol interference (isi), 254
8.2.2 bandlimiting of rectangular pulses, 254
8.2.3 isi-free signals, 255
8.2.4 nyquist’s vestigial symmetry theorem, 259
8.2.5 raised cosine filtering, 260
8.2.6 nyquist filtering for rectangular pulses, 263
8.2.7 duobinary signalling, 263
8.2.8 partial response signalling, 270
8.3 pulse filtering for optimum reception, 271
8.3.1 matched filtering, 272
contents xxxvii
8.3.2 correlation detection, 276
8.3.3 decision instant snr, 281
8.3.4 ber performance of optimum receivers, 284
8.3.5 comparison of baseband matched filtering and centre
point detection, 286
8.3.6 differences between matched filtering and correlation, 287
8.4 root raised cosine filtering, 288
8.5 equalisation, 289
8.6 summary, 292
8.7 problems, 293
9 information theory, source coding and encryption, 295
9.1 introduction, 295
9.2 information and entropy, 296
9.2.1 the information measure, 296
9.2.2 multisymbol alphabets, 297
9.2.3 commonly confused entities, 298
9.2.4 entropy of a binary source, 298
9.3 conditional entropy and redundancy, 299
9.4 information loss due to noise, 302
9.5 source coding, 305
9.5.1 code efficiency, 305
9.5.2 decoding variable length codewords, 306
9.6 variable length coding, 308
9.6.1 huffman coding, 308
9.7 source coding examples, 310
9.7.1 source coding for speech signals, 311
9.7.2 high quality speech coders, 314
9.7.3 audio coders, 315
9.7.4 string coding, 318
9.8 data encryption, 319
9.8.1 the locked box analogy, 319
9.8.2 secrecy, 320
9.8.3 substitution and permutation, 321
9.8.4 confusion, diffusion and the unicity distance, 322
9.8.5 block ciphers and stream ciphers, 324
9.8.6 product ciphers, 325
9.8.7 data encryption standard, 326
9.8.8 public key encryption, 334
9.8.9 hash functions and oaep, 339
9.8.10 hybrid public key/private key encryption and pgp, 339
9.9 authentication, 341
9.10 integrity, 342
9.11 digital signatures, 342
9.12 summary, 342
9.13 problems, 344
xxxviii contents
10 error control coding, 347
10.1 introduction, 347
10.1.1 error rate control concepts, 349
10.1.2 threshold phenomenon, 350
10.1.3 applications for error control, 351
10.2 hamming distance and codeword weight, 351
10.3 (n, k) block codes, 352
10.3.1 single parity check code, 352
10.4 probability of error in n-digit codewords, 356
10.5 linear group codes, 356
10.5.1 members of the group code family, 357
10.5.2 performance prediction, 357
10.5.3 error detection and correction capability, 358
10.6 nearest neighbour decoding of block codes, 359
10.6.1 hamming bound, 359
10.7 syndrome decoding, 360
10.7.1 the generator matrix, 360
10.7.2 syndrome table for error correction, 361
10.8 cyclic codes, 364
10.8.1 polynomial codeword generation, 365
10.8.2 interleaving, 368
10.9 encoding of convolutional codes, 369
10.9.1 tree diagram representation, 370
10.9.2 trellis diagram, 371
10.9.3 state transition diagram, 371
10.10 viterbi decoding of convolutional codes, 372
10.10.1 decoding window, 375
10.10.2 sequential decoding, 376
10.11 practical coders, 377
10.12 concatenated coding and turbo codes, 378
10.12.1 serially concatenated codes, 379
10.12.2 parallel-concatenated recursive systematic convolutional codes, 380
10.12.3 turbo decoding, 382
10.12.4 turbo code performance, 385
10.12.5 other applications of the turbo principle and ldpc codes, 386
10.13 summary, 387
10.14 problems, 388
11 bandpass modulation of a carrier signal, 390
11.1 introduction, 390
11.2 spectral and power efficiency, 391
11.3 binary if modulation, 391
11.3.1 binary amplitude shift keying (and on–off keying), 391
11.3.2 binary phase shift keying (and phase reversal keying), 395
11.3.3 binary frequency shift keying, 399
11.3.4 bfsk symbol correlation and sunde’s fsk, 402
contents xxxix
11.3.5 comparison of binary shift keying techniques, 405
11.3.6 carrier recovery, phase ambiguity and dpsk, 408
11.4 modulation techniques with increased spectral efficiency, 410
11.4.1 channel capacity, 411
11.4.2 m-symbol phase shift keying, 412
11.4.3 amplitude/phase keying and quadrature amplitude modulation, 416
11.4.4 quadrature phase shift keying (qpsk) and offset qpsk, 421
11.4.5 minimum shift keying, 428
11.4.6 gaussian msk, 431
11.4.7 trellis coded modulation, 431
11.5 power efficient modulation techniques, 437
11.5.1 multidimensional signalling and mfsk, 437
11.5.2 orthogonal frequency division multiplex (ofdm), 442
11.5.3 optimum constellation point packing, 445
11.5.4 optimum constellation point boundaries, 446
11.6 data modems, 447
11.7 summary, 448
11.8 problems, 449
12 system noise and communications link budgets, 452
12.1 introduction, 452
12.2 physical aspects of noise, 452
12.2.1 thermal noise, 453
12.2.2 non-thermal noise, 457
12.2.3 combining white noise sources, 460
12.3 system noise calculations, 463
12.3.1 noise temperature, 463
12.3.2 noise temperature of cascaded subsystems, 465
12.3.3 noise factor and noise figure, 468
12.4 radio communication link budgets, 471
12.4.1 antenna gain, effective area and efficiency, 471
12.4.2 free space and plane earth signal budgets, 476
12.4.3 antenna temperature and radio noise budgets, 482
12.4.4 receiver equivalent input cnr, 485
12.4.5 multipath fading and diversity reception, 486
12.5 fibre optic transmission links, 488
12.5.1 fibre types, 489
12.5.2 fibre transmission systems, 491
12.5.3 optical sources, 492
12.5.4 optical detectors, 492
12.5.5 optical amplifiers, 492
12.5.6 optical repeater and link budgets, 494
12.5.7 optical fdm, 496
12.5.8 optical signal routers, 496
12.6 summary, 496
12.7 problems, 497
xl contents
13 communication systems simulation, 500
13.1 introduction, 500
13.2 equivalent complex baseband representations, 502
13.2.1 equivalent baseband signals, 502
13.2.2 equivalent baseband systems, 503
13.2.3 equivalent baseband system output, 505
13.2.4 equivalent baseband noise, 509
13.3 sampling and quantisation, 512
13.3.1 sampling equivalent baseband signals, 512
13.3.2 quantisation, 514
13.4 modelling of signals, noise and systems, 514
13.4.1 random numbers, 514
13.4.2 random digital symbol streams, 516
13.4.3 noise and interference, 520
13.4.4 time invariant linear systems, 521
13.4.5 non-linear and time varying systems, 522
13.5 transformation between time and frequency domains, 523
13.5.1 dft, 524
13.5.2 dfs, 526
13.5.3 dfs spectrum and rearrangement of spectral lines, 526
13.5.4 conservation of information, 527
13.5.5 phasor interpretation of dfs, 527
13.5.6 inverse dfs and dft, 528
13.5.7 dft accuracy, 529
13.6 discrete and cyclical convolution, 535
13.7 estimation of ber, 538
13.7.1 monte carlo simulation, 538
13.7.2 quasi-analytic simulation, 540
13.8 summary, 546
part three applications, 549
14 fixed-point microwave communications, 551
14.1 introduction, 551
14.2 terrestrial microwave links, 551
14.2.1 analogue systems, 553
14.2.2 digital systems, 554
14.2.3 los link design, 556
14.2.4 other propagation considerations for terrestrial links, 565
14.3 fixed-point satellite communications, 572
14.3.1 satellite frequency bands and orbital spacing, 574
14.3.2 earth station look angles and satellite range, 575
14.3.3 satellite link budgets, 577
14.3.4 slant path propagation considerations, 583
14.3.5 analogue fdm/fm/fdma trunk systems, 589
14.3.6 digital tdm/psk/tdma trunk systems, 593
contents xli
14.3.7 da-tdma, dsi and random access systems, 598
14.3.8 economics of satellite communications, 599
14.3.9 vsat systems, 599
14.3.10 satellite switched tdma and onboard signal processing, 599
14.4 summary, 601
14.5 problems, 602
15 mobile and cellular radio, 605
15.1 introduction, 605
15.1.1 private mobile radio, 605
15.1.2 radio paging systems, 607
15.2 mobile radio link budget and channel characteristics, 607
15.2.1 prediction of median signal strength, 608
15.2.2 slow and fast fading, 610
15.2.3 dispersion, frequency selective fading and coherence bandwidth, 611
15.2.4 multipath modelling and simulation, 612
15.3 nationwide cellular radio communications, 614
15.3.1 introduction, 614
15.3.2 personal cordless communications, 615
15.3.3 analogue cellular radio communication, 616
15.3.4 cell sizes, 616
15.3.5 system configuration, 619
15.4 digital tdma terrestrial cellular systems, 620
15.4.1 tdma systems, 620
15.4.2 tdma data format and modulation, 621
15.4.3 speech and channel coding, 622
15.4.4 other operational constraints, 623
15.4.5 trunked radio for paramilitary use, 624
15.5 code division multiple access (cdma), 624
15.5.1 the cdma concept, 624
15.5.2 cdma receiver design, 626
15.5.3 spreading sequence design, 629
15.5.4 data modulation, 633
15.5.5 cdma multipath processing, 633
15.5.6 the cdmaone system, 634
15.5.7 frequency hopped transmission, 638
15.6 mobile satellite based systems, 640
15.7 third generation mobile cellular standards, 642
15.7.1 mobile data transmission, 642
15.7.2 3g systems, 643
15.7.3 4g or 3g evolution, 645
15.8 summary, 645
15.9 problems, 646
16 video transmission and storage, 647
16.1 introduction, 647
16.2 colour representation, 648
xlii contents
16.3 conventional tv transmission systems, 650
16.3.1 pal encoding, 650
16.3.2 pal television receiver, 652
16.3.3 other encoding schemes, 653
16.4 high definition tv, 653
16.4.1 what is hdtv, 653
16.4.2 transmissions, 654
16.5 digital video, 655
16.6 video data compression, 656
16.6.1 run length coding, 657
16.6.2 conditional replenishment, 658
16.6.3 transform coding, 658
16.7 compression standards, 659
16.7.1 cost 211, 659
16.7.2 jpeg, 660
16.7.3 mpeg-1 and mpeg-2, 662
16.7.4 mpeg-4 and mpeg-7, 664
16.7.5 h.261, h.263 and h.264, 665
16.7.6 model based coding, 666
16.8 digital video broadcast, 668
16.9 packet video, 669
16.10 other multimedia services, 670
16.11 summary, 670
16.12 problems, 672
part four networks, 673
17 network applications, topologies and architecture, 675
17.1 introduction, 675
17.2 network applications, 676
17.3 network function, 678
17.4 network classification, 678
17.5 switched network topologies and representation, 680
17.5.1 star or hub, 681
17.5.2 tree, 682
17.5.3 mesh, 682
17.5.4 matrix representation, 683
17.6 generic network switching philosophies, 684
17.6.1 circuit switching, 684
17.6.2 message switching, 685
17.6.3 packet switching, 685
17.7 broadcast network topologies, 688
17.7.1 bus or multidrop, 688
17.7.2 passive ring, 689
17.7.3 active ring, 690
contents xliii
17.8 transmission media, 691
17.9 interconnected networks, 691
17.10 user and provider network views, 693
17.11 connection-oriented and connectionless services, 696
17.12 layered network architectures, 696
17.12.1 iso osi protocol reference model, 697
17.12.2 network layers in use, 700
17.13 summary, 702
17.14 problems, 702
18 network protocols, 704
18.1 introduction, 704
18.2 physical layer, 704
18.2.1 a physical layer protocol – x.21, 705
18.3 data-link layer, 709
18.3.1 synchronisation, 710
18.3.2 error control, 713
18.3.3 flow control, 727
18.3.4 a data-link protocol – hdlc, 730
18.4 network layer, 733
18.4.1 routing, 734
18.4.2 congestion control, 740
18.4.3 error control, 741
18.4.4 quality of service, 741
18.4.5 a connection-oriented network level protocol – x.25 plp, 741
18.4.6 a connectionless network level protocol (clnp), 745
18.4.7 use of primitives, 750
18.5 transport layer, 752
18.5.1 message segmentation and reassembly, 753
18.5.2 multiplexing and parallel virtual circuit transmission, 753
18.5.3 end-to-end error and flow control, 754
18.5.4 use of well known and ephemeral ports, 754
18.5.5 a transport level protocol – tp4, 754
18.6 session layer, 759
18.6.1 session connection, maintenance and release, 759
18.6.2 dialogue supervision, 760
18.6.3 recovery, 760
18.6.4 a session level protocol – iso-sp, 760
18.7 presentation layer, 764
18.7.1 translation between local and transfer syntaxes, 764
18.7.2 abstract syntax notation 1 (asn.1), 765
18.7.3 a presentation level protocol – iso-pp, 766
18.8 application layer, 766
18.9 non-osi protocol stacks, 766
18.10 summary, 767
18.11 problems, 769
xliv contents
19 network performance using queueing theory (m.e. woodward), 771
19.1 introduction, 771
19.1.1 the arrival process, 772
19.1.2 queueing systems, 775
19.2 the m/m/1 queue, 776
19.2.1 the equilibrium probabilities, 776
19.2.2 performance measures, 778
19.3 the m/m/1/n queue, 780
19.3.1 general markovian queueing equations, 782
19.3.2 the m/m/n/n queue, 786
19.3.3 the m/m/n/n/k queue, 788
19.3.4 m/m/n/n+j queue (erlang-c equation), 789
19.3.5 distribution of waiting times, 792
19.4 m/m/n/k/k queue: queueing behaviour in a mobile
communication system, 793
19.4.1 speech source model, 794
19.4.2 equilibrium probability, 794
19.5 summary, 796
19.6 problems, 797
20 switched networks and wans, 799
20.1 introduction, 799
20.2 wan characteristics and classification, 800
20.3 application of graph theory to core networks, 802
20.3.1 topology, cost and capacity matrices, 802
20.3.2 network capacity, 803
20.3.3 network connectivity, 808
20.4 the uk public network, 811
20.4.1 the traditional analogue network, 812
20.4.2 the modern digital network, 813
20.5 multiplexing, 816
20.5.1 the plesiochronous digital hierarchy, 816
20.5.2 sdh and sonet, 824
20.6 circuit switching, 836
20.6.1 space switching, 836
20.6.2 time switching, 836
20.6.3 time–space–time and space–time–space switching, 838
20.6.4 multi-stage space switches, 839
20.6.5 switch connectivity, 845
20.6.6 concentration and expansion, 845
20.6.7 switch design, 846
20.6.8 probability of blocking, 849
20.6.9 circuit switched data over the pstn, 851
20.7 packet switching, 855
20.7.1 packet switched data over the pdn, 856
20.7.2 frame relay, 861
contents xlv
20.8 integrated services digital network (isdn), 862
20.8.1 isdn structure, 862
20.8.2 basic and primary rate access, 863
20.8.3 isdn services, 865
20.9 signalling, 866
20.9.1 in-channel and common channel signalling, 867
20.9.2 signalling system no. 7, 868
20.10 asynchronous transfer mode and the broadband isdn, 870
20.10.1 transport mechanism, 871
20.10.2 service classes, 873
20.10.3 connection admission control, 874
20.10.4 access protocols, 875
20.10.5 synchronous versus asynchronous transfer modes, 875
20.10.6 transition from atm to ip, 876
20.11 access technologies, 877
20.11.1 digital subscriber line, 877
20.11.2 fibre, 881
20.11.3 cable, 884
20.11.4 broadband fixed wireless access (ieee 802.16), 890
20.11.5 comparison of access network technologies, 903
20.11.6 convergence of access network services, 903
20.12 summary, 906
20.13 problems, 908
21 broadcast networks and lans, 911
21.1 introduction, 911
21.2 lan topologies, 912
21.3 lan protocol stack, 912
21.3.1 fixed access multiplexing, 913
21.3.2 polling, 913
21.3.3 token passing, 913
21.3.4 contention, 914
21.4 popular wired lan standards, 915
21.4.1 ethernet (ieee 802.3), 916
21.4.2 token ring (ieee 802.5), 923
21.5 wireless lans, 933
21.5.1 wlan (ieee 802.11), 934
21.5.2 mimo techniques, 942
21.5.3 hiperlan, 947
21.6 metropolitan area networks, 951
21.6.1 fibre distributed data interface, 951
21.6.2 distributed queue dual bus, 955
21.6.3 atm mans/lans, 958
21.7 wireless personal area networks, 960
21.7.1 bluetooth (ieee 802.15.1), 960
21.7.2 other ieee 802.15 pan technologies, 969
xlvi contents
21.8 home networking technologies, 974
21.8.1 wired home networks, 975
21.8.2 wireless home networks, 976
21.9 residential gateways, 978
21.10 summary, 979
21.11 problems, 981
appendix a. tabulated values of the error function, 982
appendix b. summations of common series, 985
appendix c. international alphabet no. 5 (ascii code set), 986
appendix d. lan/man examples, 987
standards, 989
www addresses, 993
bibliography, 995
index, 1011