Preface xxi
Acknowledgements xxiii
About the Companion Website xxv
1 Overview of Communication Systems 1
1.1 Introduction 1
1.2 Nonelectrical Telecommunication 2
1.2.1 Verbal Nonelectrical Telecommunication 2
1.2.2 Visual Nonelectrical Telecommunication 3
1.2.2.1 Flags, Smoke, and Bonfires 3
1.2.2.2 Heliography 4
1.2.2.3 Semaphore 4
1.2.2.4 Demerits of Visual Nonelectrical Telecommunication 5
1.3 Modern Telecommunication 5
1.3.1 Developments in Character Codes 7
1.3.1.1 Morse Code 7
1.3.1.2 Baudot Code 7
1.3.1.3 Hollerith Code 8
1.3.1.4 EBCDIC Code 9
1.3.1.5 ASCII Code 9
1.3.1.6 ISO 8859 Code 10
1.3.1.7 Unicode 11
1.3.2 Developments in Services 13
1.3.2.1 Telegram 13
1.3.2.2 Telex 14
1.3.2.3 Facsimile 14
1.3.2.4 The Digital Era 15
1.3.3 Developments in Transmission Media 16
1.3.3.1 Copper Cable 17
1.3.3.2 Radio 18
1.3.3.3 Optical Fibre 19
1.4 Communication System Elements 21
1.4.1 Information Source 21
1.4.1.1 Audio Input Devices 22
1.4.1.2 Video Input Devices 23
1.4.1.3 Data Input Devices 23
1.4.1.4 Sensors 23
1.4.2 Information Sink 24
1.4.2.1 Audio Output Device 24
1.4.2.2 Visual Display Devices 26
1.4.2.3 Storage Devices 28
1.4.3 Transmitter 29
1.4.4 Receiver 31
1.5 Classification of Communication Systems 32
1.5.1 Simplex Versus Duplex Communication Systems 32
1.5.2 Analogue Versus Digital Communication Systems 33
1.5.3 Baseband Versus Modulated Communication Systems 35
1.5.3.1 Analogue Baseband Communication System 35
1.5.3.2 Discrete Baseband Communication System 36
1.5.3.3 Digital Baseband Communication System 41
1.5.3.4 Modulated Communication Systems 44
1.5.4 Circuit Versus Packet Switching 47
1.5.4.1 Circuit Switching 48
1.5.4.2 Packet Switching 50
1.6 Epilogue 53
References 53
Review Questions 53
2 Introduction to Signals and Systems 57
2.1 Introduction 57
2.2 What Is a Signal? 58
2.3 Forms of Telecommunication Signals 58
2.4 Subjective Classification of Telecommunication Signals 60
2.4.1 Speech 60
2.4.2 Music 62
2.4.3 Video 63
2.4.4 Digital Data 64
2.4.5 Facsimile 64
2.4.6 Ancillary and Control Signals 65
2.5 Objective Classification of Telecommunication Signals 65
2.5.1 Analogue or Digital 65
2.5.2 Periodic or Nonperiodic 67
2.5.3 Deterministic or Random 68
2.5.4 Power or Energy 69
2.5.5 Even or Odd 69
2.6 Special Waveforms and Signals 71
2.6.1 Unit Step Function 74
2.6.2 Signum Function 74
2.6.3 Rectangular Pulse 75
2.6.4 Ramp Pulse 76
2.6.5 Triangular Pulse 77
2.6.6 Sawtooth and Trapezoidal Pulses 77
2.6.7 Unit Impulse Function 78
2.6.8 Sinc Function 79
2.7 Sinusoidal Signals 81
2.7.1 Qualitative Introduction 82
2.7.2 Parameters of a Sinusoidal Signal 83
2.7.2.1 Angle 86
2.7.2.2 Amplitude 87
2.7.2.3 Angular Frequency 87
2.7.2.4 Frequency 87
2.7.2.5 Period 88
2.7.2.6 Wavelength 88
2.7.2.7 Initial Phase 88
2.7.2.8 Phase Difference 89
2.7.3 Addition of Sinusoids 92
2.7.3.1 Same Frequency and Phase 93
2.7.3.2 Same Frequency but Different Phases 93
2.7.3.3 Multiple Sinusoids of Different Frequencies 97
2.7.3.4 Beats Involving Two Sinusoids 97
2.7.4 Multiplication of Sinusoids 99
2.8 Logarithmic Units 99
2.8.1 Logarithmic Units for System Gain 101
2.8.2 Logarithmic Units for Voltage, Power, and Other Quantities 102
2.8.3 Logarithmic Unit Dos and Don'ts 104
2.9 Calibration of a Signal Transmission Path 107
2.10 Systems and Their Properties 109
2.10.1 Memory 109
2.10.2 Stability 111
2.10.3 Causality 112
2.10.4 Linearity 113
2.10.5 Time Invariance 116
2.10.6 Invertibility 118
2.11 Summary 121
Questions 122
3 Time Domain Analysis of Signals and Systems 127
3.1 Introduction 127
3.2 Basic Signal Operations 128
3.2.1 Time Shifting (Signal Delay and Advance) 128
3.2.2 Time Reversal 130
3.2.3 Time Scaling 132
3.3 Random Signals 134
3.3.1 Random Processes 134
3.3.2 Random Signal Parameters 135
3.3.3 Stationarity and Ergodicity 138
3.4 Standard Distribution Functions 139
3.4.1 Gaussian or Normal Distribution 139
3.4.2 Rayleigh Distribution 143
3.4.3 Lognormal Distribution 148
3.4.4 Rician Distribution 153
3.4.5 Exponential and Poisson Distributions 157
3.5 Signal Characterisation 162
3.5.1 Mean 162
3.5.2 Power 163
3.5.3 Energy 167
3.5.4 Root-mean-square Value 168
3.5.5 Autocorrelation 171
3.5.6 Covariance and Correlation Coefficient 176
3.6 Linear Time Invariant System Analysis 180
3.6.1 LTI System Response 181
3.6.2 Evaluation of Convolution Integral 186
3.6.3 Evaluation of Convolution Sum 190
3.6.4 Autocorrelation and Convolution 196
3.7 Summary 197
References 198
Questions 198
4 Frequency Domain Analysis of Signals and Systems 203
4.1 Introduction 203
4.2 Fourier Series 205
4.2.1 Sinusoidal Form of Fourier Series 206
4.2.1.1 Time Shifting 211
4.2.1.2 Time Reversal 212
4.2.1.3 Even and Odd Functions 212
4.2.1.4 Piecewise Linear Functions 214
4.2.2 Complex Exponential Form of Fourier Series 222
4.2.3 Amplitude and Phase Spectra 224
4.2.3.1 Double-sided Spectrum 227
4.2.3.2 Single-sided Spectrum 228
4.2.4 Fourier Series Application to Selected Waveforms 235
4.2.4.1 Flat-top-sampled Signal 235
4.2.4.2 Binary ASK Signal and Sinusoidal Pulse Train 243
4.2.4.3 Trapezoidal Pulse Train 248
4.3 Fourier Transform 253
4.3.1 Properties of the Fourier Transform 257
4.3.1.1 Even and Odd Functions 257
4.3.1.2 Linearity 258
4.3.1.3 Time Shifting 258
4.3.1.4 Frequency Shifting 258
4.3.1.5 Time Scaling 258
4.3.1.6 Time Reversal 259
4.3.1.7 Complex Conjugation 259
4.3.1.8 Duality 259
4.3.1.9 Differentiation 259
4.3.1.10 Integration 260
4.3.1.11 Multiplication 260
4.3.1.12 Convolution 260
4.3.1.13 Areas 260
4.3.1.14 Energy 261
4.3.2 Table of Fourier Transforms 263
4.3.3 Fourier Transform of Periodic Signals 268
4.4 Discrete Fourier Transform 270
4.4.1 Properties of the Discrete Fourier Transform 275
4.4.1.1 Periodicity 275
4.4.1.2 Symmetry 276
4.4.2 Fast Fourier Transform 277
4.4.3 Practical Issues in DFT Implementation 283
4.4.3.1 Aliasing 283
4.4.3.2 Frequency Resolution 284
4.4.3.3 Spectral Leakage 285
4.4.3.4 Spectral Smearing 285
4.4.3.5 Spectral Density and Its Variance 288
4.5 Laplace and z-transforms 291
4.5.1 Laplace Transform 291
4.5.2 z-transform 292
4.6 Inverse Relationship Between Time and Frequency Domains 295
4.7 Frequency Domain Characterisation of LTI Systems 297
4.7.1 Transfer Function 297
4.7.2 Output Spectral Density of LTI Systems 301
4.7.3 Signal and System Bandwidths 302
4.7.3.1 Subjective Bandwidth 303
4.7.3.2 Null Bandwidth 303
4.7.3.3 3 dB Bandwidth 304
4.7.3.4 Fractional Power Containment Bandwidth 306
4.7.3.5 Noise Equivalent Bandwidth 308
4.7.4 Distortionless Transmission 311
4.7.5 Attenuation and Delay Distortions 313
4.7.6 Nonlinear Distortions 314
4.8 Summary 316
References 317
Questions 317
5 Transmission Media 327
5.1 Introduction 327
5.2 Metallic Line Systems 328
5.2.1 Wire Pairs 328
5.2.2 Coaxial Cable 332
5.2.3 Attenuation in Metallic Lines 333
5.3 Transmission Line Theory 334
5.3.1 Incident and ReflectedWaves 337
5.3.2 Secondary Line Constants 338
5.3.3 Characteristic Impedance 340
5.3.4 Reflection and Transmission Coefficients 342
5.3.5 StandingWaves 345
5.3.6 Line Impedance and Admittance 347
5.3.7 Line Termination and Impedance Matching 353
5.3.8 Scattering Parameters 359
5.3.9 Smith Chart 363
5.4 Optical Fibre 365
5.4.1 Optical Fibre Types 367
5.4.1.1 Single-mode Step Index 368
5.4.1.2 Multimode Step Index Fibre 368
5.4.1.3 Multimode Graded Index 369
5.4.2 Coupling of Light into Fibre 369
5.4.3 Attenuation in Optical Fibre 371
5.4.3.1 Intrinsic Fibre Loss 371
5.4.3.2 Extrinsic Fibre Loss 375
5.4.4 Dispersion in Optical Fibre 376
5.4.4.1 Intermodal Dispersion 376
5.4.4.2 Intramodal Dispersion 377
5.5 Radio 380
5.5.1 Maxwell's Equations 382
5.5.2 RadioWave Propagation Modes 384
5.5.2.1 GroundWave 386
5.5.2.2 SkyWave 386
5.5.2.3 Line-of-sight (LOS) 387
5.5.2.4 Satellite Communications 387
5.5.2.5 Mobile Communications 388
5.5.2.6 Ionospheric Scatter 388
5.5.2.7 Tropospheric Scatter 388
5.5.3 RadioWave Propagation Effects 388
5.5.3.1 Ionospheric Effects 388
5.5.3.2 Tropospheric Attenuation 390
5.5.3.3 Tropospheric Scintillation 393
5.5.3.4 Depolarisation 394
5.5.3.5 Tropospheric Refraction 395
5.5.4 Reflection and Refraction 397
5.5.5 Rough Surface Scattering 406
5.5.6 Diffraction 408
5.5.6.1 Diffraction Configuration and Terms 408
5.5.6.2 Fresnel Zones 410
5.5.6.3 Knife-edge Diffraction Loss 411
5.5.7 Path Loss 416
5.5.7.1 Free Space Path Loss 416
5.5.7.2 Plane Earth Propagation Path Loss 418
5.5.7.3 Terrestrial Cellular Radio Path Loss 421
5.5.8 Radio Frequency Allocation 424
5.6 Summary 424
References 425
Questions 426
6 Noise in Communication Systems 431
6.1 Introduction 431
6.2 Physical Sources of Random Noise 432
6.2.1 Thermal or Johnson Noise 432
6.2.2 Quantisation Noise 433
6.2.3 Radio or Sky Noise 433
6.2.4 Shot Noise 435
6.2.5 Partition Noise 435
6.2.6 Quantum Noise 435
6.2.7 Flicker or 1/f Noise 436
6.3 Additive White Gaussian Noise 437
6.3.1 Gaussian PDF of Noise 438
6.3.2 White Noise 439
6.3.3 Canonical and Envelope Representations of Noise 444
6.4 System Noise Calculations 448
6.4.1 Available Noise Power 448
6.4.2 Equivalent Noise Temperature 450
6.4.3 Noise Figure of a Single System 451
6.4.4 Noise Figure of Cascaded Systems 454
6.4.5 Overall System Noise Temperature 457
6.4.6 Signal-to-noise Ratio 459
6.5 Noise Effects in Communication Systems 462
6.5.1 SNR in Analogue Communication Systems 462
6.5.2 BER in Digital Communication Systems 465
6.6 Summary 469
References 470
Questions 470
7 Amplitude Modulation 473
7.1 Introduction 473
7.2 AM Signals: Time Domain Description 474
7.2.1 AMWaveform 474
7.2.2 Sketching AMWaveforms 475
7.2.3 Modulation Factor 476
7.3 Spectrum and Power of Amplitude Modulated Signals 480
7.3.1 Sinusoidal Modulating Signal 480
7.3.2 Arbitrary Message Signal 482
7.3.3 Power 485
7.4 AM Modulators 488
7.4.1 Generation of AM Signal 488
7.4.1.1 Linearly-varied-gain Modulator 488
7.4.1.2 Switching and Square-law Modulators 489
7.4.2 AM Transmitters 491
7.4.2.1 Low-level Transmitter 491
7.4.2.2 High-level Transmitter 492
7.5 AM Demodulators 492
7.5.1 Diode Demodulator 493
7.5.2 Coherent Demodulator 496
7.5.3 AM Receivers 498
7.5.3.1 Tuned Radio Frequency (RF) Receiver 498
7.5.3.2 Superheterodyne Receiver 499
7.6 Merits, Demerits, and Application of AM 501
7.7 Variants of AM 502
7.7.1 DSB 502
7.7.1.1 Waveform and Spectrum of DSB 502
7.7.1.2 DSB Modulator 504
7.7.1.3 DSB Demodulator 507
7.7.1.4 DSB Applications 509
7.7.2 SSB 510
7.7.2.1 Merits and Demerits of SSB 511
7.7.2.2 SSB Modulators 514
7.7.2.3 SSB Demodulator 516
7.7.2.4 Applications of SSB 517
7.7.3 ISB 518
7.7.3.1 ISB Modulator 518
7.7.3.2 ISB Demodulator 518
7.7.3.3 ISB Merits, Demerit, and Application 520
7.7.4 VSB 520
7.7.4.1 VSB Modulator 521
7.7.4.2 VSB Demodulator 522
7.8 Summary 524
Questions 525
8 Frequency and Phase Modulation 529
8.1 Introduction 529
8.2 Basic Concepts of FM and PM 530
8.2.1 Frequency Modulation Concepts 531
8.2.2 Phase Modulation Concepts 535
8.2.3 Relationship Between FM and PM 537
8.2.3.1 Frequency Variations in PM 537
8.2.3.2 Phase Variations in FM 540
8.3 FM and PMWaveforms 543
8.3.1 Sketching SimpleWaveforms 543
8.3.2 GeneralWaveform 544
8.4 Spectrum and Power of FM and PM 549
8.4.1 Narrowband FM and PM 549
8.4.1.1 Frequency Components 549
8.4.1.2 Comparing AM, NBFM, and NBPM 551
8.4.1.3 Amplitude Variations in NBFM and NBPM 556
8.4.2 Wideband FM and PM 557
8.4.2.1 Spectrum 558
8.4.2.2 Power 560
8.4.2.3 Bandwidth 563
8.4.2.4 FM or PM? 567
8.5 FM and PM Modulators 567
8.5.1 Narrowband Modulators 567
8.5.2 Indirect Wideband Modulators 569
8.5.3 Direct Wideband Modulators 572
8.5.3.1 LCO Modulator 573
8.5.3.2 VCO Modulator 575
8.6 FM and PM Demodulators 576
8.6.1 Direct Demodulator 577
8.6.1.1 Filter-based Demodulator 577
8.6.1.2 Digital Demodulator 577
8.6.2 Indirect Demodulator 577
8.6.2.1 PLL Demodulation Process 579
8.6.2.2 PLL States 580
8.6.2.3 PLL Features 580
8.6.3 Phase Demodulator 580
8.6.4 Frequency Discriminators 581
8.6.4.1 Differentiators 581
8.6.4.2 Tuned Circuits 583
8.7 FM Transmitter and Receiver 584
8.7.1 Transmitter 584
8.7.2 SNR and Bandwidth Trade-off 586
8.7.3 Pre-emphasis and De-emphasis 586
8.7.4 Receiver 588
8.8 Noise Effect in FM 588
8.9 Overview of FM and PM Features 594
8.9.1 Merits 594
8.9.2 Demerits 594
8.9.3 Applications 595
8.10 Summary 595
Questions 595
9 Sampling 599
9.1 Introduction 599
9.2 Sampling Theorem 599
9.3 Proof of Sampling Theorem 600
9.3.1 Lowpass Signals 602
9.3.2 Bandpass Signals 603
9.3.3 Sampling at Nyquist Rate 606
9.4 Aliasing 607
9.5 Anti-alias Filter 613
9.6 Non-instantaneous Sampling 615
9.6.1 Natural Sampling 616
9.6.2 Flat-top Sampling 618
9.6.3 Aperture Effect 622
9.7 Summary 623
Questions 624
Reference 625
10 Digital Baseband Coding 627
10.1 Introduction 627
10.2 Concept and Classes of Quantisation 628
10.3 Uniform Quantisation 634
10.3.1 Quantisation Noise 635
10.3.2 Dynamic Range of a Quantiser 636
10.3.3 Signal-to-quantisation-noise Ratio (SQNR) 636
10.3.4 Design Considerations 639
10.3.5 Demerits of Uniform Quantisation 640
10.4 Nonuniform Quantisation 641
10.4.1 Compressor Characteristic 642
10.4.2 A-law Companding 644
10.4.3 -law Companding 645
10.4.4 Companding Gain and Penalty 647
10.4.5 Practical Nonlinear PCM 650
10.4.6 SQNR of Practical Nonlinear PCM 657
10.5 Differential PCM (DPCM) 661
10.5.1 Adaptive Differential Pulse Code Modulation (ADPCM) 664
10.5.2 Delta Modulation 664
10.5.2.1 Quantisation Error 664
10.5.2.2 Prediction Filter 666
10.5.2.3 Design Parameters 666
10.5.2.4 Merits and Demerits of DM 666
10.5.2.5 Adaptive Delta Modulation (ADM) 668
10.5.2.6 Delta Sigma Modulation 668
10.6 Low Bit Rate Speech Coding 668
10.6.1 Waveform Coders 671
10.6.2 Vocoders 671
10.6.2.1 IMBE 672
10.6.2.2 LPC 672
10.6.2.3 MELP 673
10.6.3 Hybrid Coders 673
10.6.3.1 APC 673
10.6.3.2 MPE-LPC 673
10.6.3.3 CELP 673
10.7 Line Codes 674
10.7.1 NRZ Codes 674
10.7.2 RZ Codes 675
10.7.3 Biphase Codes 676
10.7.4 RLL Codes 676
10.7.5 Block Codes 677
10.8 Summary 680
Reference 681
Questions 681
11 Digital Modulated Transmission 683
11.1 Introduction 683
11.2 Orthogonality of Energy Signals 687
11.3 Signal Space 689
11.3.1 Interpretation of Signal-space Diagrams 690
11.3.2 Complex Notation for 2D Signal Space 693
11.3.3 Signal-spaceWorked Examples 694
11.4 Digital Transmission Model 699
11.5 Noise Effects 701
11.6 Symbol and Bit Error Ratios 703
11.6.1 Special Cases 705
11.6.2 Arbitrary Binary Transmission 708
11.7 Binary Modulation 712
11.7.1 ASK 712
11.7.2 PSK 714
11.7.3 FSK 715
11.7.3.1 Generation 715
11.7.3.2 Spectrum 716
11.7.3.3 Frequency Spacing and MSK 716
11.7.4 Minimum Transmission Bandwidth 718
11.8 Coherent Binary Detection 719
11.8.1 ASK Detector 719
11.8.2 PSK Detector 721
11.8.3 FSK Detector 721
11.9 Noncoherent Binary Detection 723
11.9.1 Noncoherent ASK Detector 725
11.9.2 Noncoherent FSK Detector 727
11.9.3 DPSK 727
11.10 M-ary Transmission 730
11.10.1 Bandwidth Efficiency 730
11.10.2 M-ary ASK 732
11.10.2.1 M-ary ASK Modulator 732
11.10.2.2 M-ary ASK Detector 734
11.10.2.3 BER of M-ary ASK 734
11.10.3 M-ary PSK 737
11.10.3.1 QPSK Modulator and Detector 738
11.10.3.2 M-ary PSK Modulator and Detector 740
11.10.3.3 BER of M-ary PSK 743
11.10.4 M-ary FSK 746
11.10.4.1 M-ary FSK Modulator and Detector 746
11.10.4.2 BER of M-ary FSK 746
11.10.4.3 Noise-bandwidth Trade-off in M-ary FSK 748
11.10.5 M-ary APSK 749
11.10.5.1 16-APSK 749
11.10.5.2 BER of Square M-ary APSK 752
11.11 Design Parameters 754
11.12 Summary 757
Reference 758
Questions 759
12 Pulse Shaping and Detection 763
12.1 Introduction 763
12.2 Anti-ISI Filtering 765
12.2.1 Nyquist Filtering 767
12.2.2 Raised Cosine Filtering 769
12.2.3 Square Root Raised Cosine Filtering 771
12.2.4 Duobinary Signalling 774
12.2.4.1 Cosine Filter 774
12.2.4.2 Signal Power Trade-off 777
12.2.4.3 Sine Filter 778
12.2.4.4 Polybinary Signalling 779
12.3 Information Capacity Law 780
12.4 The Digital Receiver 787
12.4.1 Adaptive Equalisation 787
12.4.2 Matched Filter 787
12.4.2.1 Specification of a Matched Filter 788
12.4.2.2 Matched Filter by Correlation 790
12.4.2.3 Matched FilterWorked Examples 791
12.4.3 Clock Extraction 797
12.4.4 Eye Diagrams 799
12.5 Summary 799
References 801
Questions 801
13 Multiplexing Strategies 805
13.1 Introduction 805
13.2 Frequency Division Multiplexing 809
13.2.1 General Concepts 809
13.2.2 Demerits of Flat-level FDM 812
13.2.3 Future of FDM Technology 813
13.2.4 FDM Hierarchies 814
13.2.4.1 UK System 816
13.2.4.2 European System 820
13.2.4.3 Bell System 821
13.2.4.4 Nonvoice Signals 822
13.2.5 Wavelength Division Multiplexing 823
13.3 Time Division Multiplexing 825
13.3.1 General Concepts 825
13.3.2 Plesiochronous Digital Hierarchy 827
13.3.2.1 E1 System 827
13.3.2.2 T1 and J1 Systems 832
13.3.2.3 PDH Problems 838
13.3.3 Synchronous Digital Hierarchy 838
13.3.3.1 SDH Rates 839
13.3.3.2 SDH Frame Structure 839
13.3.3.3 SONET 844
13.3.4 ATM 846
13.3.4.1 ATM Layered Architecture 847
13.3.4.2 ATM Network Components 850
13.3.4.3 ATM Cell Header 851
13.3.4.4 ATM Features Summary 852
13.3.4.5 ATM Versus IP 852
13.4 Code Division Multiplexing 853
13.4.1 Types of Spread Spectrum Modulation 853
13.4.2 CDM Transmitter 856
13.4.3 CDM Receiver 858
13.4.4 Crucial Features of CDM 863
13.4.4.1 Synchronisation 863
13.4.4.2 Cross-correlation of PN Codes 864
13.4.4.3 Power Control 864
13.4.4.4 Processing Gain 866
13.5 Multiple Access 867
13.5.1 FDMA 868
13.5.2 TDMA 869
13.5.3 CDMA 871
13.5.4 Hybrid Schemes 872
13.6 Summary 873
Questions 874
Appendix A Character Codes 877
Appendix B Trigonometric Identities 883
Appendix C Tables and Constants 885
C.1 Constants 885
C.2 SI Units 886
C.3 Complementary Error Function erfc(x) and Q function Q(x) 887
Index 891
