Main description:

This book contains material that should interest students of electrical engineering and computer science specializing in digital communications and also practicing electrical engineers who apply digital communications techni­ ques to telecommunication systems, digital radio, digital satellites, fiber optics, and the physical layer of computer networks. This book is an outgrowth of lecture notes prepared over a number of years at various universities. In the earlier years I benefited immensely from t 5 the excellent textbooks and monographs in preparing my notes. - With passing time I had to rely more and more on the current periodical literature, mainly the IEEE Transactions and the Bell System Technical Journal. Although the book is intended mainly for those who have already had an introduction to communications, as usually taught in an undergraduate course, it can also be used without this background. For that purpose I concentrated most of the necessary mathematics in Chapter I. If the mathematics is not an obstacle, the reader can start with Chapter 2. I tried, as far as possible, to make each chapter independent of the other chapters, and for that reason many concepts and notations have been defined several times. To keep the book at a reasonable length, however, it was impossible, in most cases, not to rely on derivations and results of previous chapters.

Contents:

1. Signals, Filters, Random Variables and Random Processes.- 1.1 Introduction.- 1.2 Deterministic signals and their transforms.- 1.2.1 Real and complex signals.- 1.2.2 Properties of signals.- 1.2.3 Expansion of signals into orthogonal series.- 1.2.4 Fourier transforms.- 1.2.5 Laplace transforms.- 1.3 Linear systems and filters.- 1.3.1 Impulse response and transfer function.- 1.3.2 Nondistorting filters.- 1.3.3 Band-limiting filters.- 1.3.4 Time-variant, linear filters.- 1.3.5 Hilbert transform.- 1.4 Equivalence of baseband and bandpass signals and filters.- 1.4.1 Baseband and bandpass signals.- 1.4.2 Baseband and bandpass filters.- 1.4.3 Bandpass filters in tandem.- 1.4.4 Response of bandpass filters to bandpass signal.- 1.4.5 Equivalence with respect to different carrier frequencies.- 1.4.6 Baseband equivalence of arbitrary function.- 1.5 Random variables.- 1.5.1 Sets.- 1.5.2 Events and probabilities.- 1.5.3 Random variable.- 1.5.4 Function of random variable.- 1.5.5 Averages.- 1.6 Two random variables.- 1.6.1 Definition and probabilities.- 1.6.2 Averages.- 1.6.3 Tansformations.- 1.6.4 Complex random variables.- 1.7 Random vectors.- 1.7.1 Definition and probabilities.- 1.7.2 Transformation and averages.- 1.8 Random process.- 1.8.1 Definitions.- 1.8.2 Correlation.- 1.8.3 Effect of linear systems on random processes.- 1.8.4 Complex random process.- 1.8.5 Equivalence of bandpass and baseband random noise.- 1.9 Summary.- 1.10 Problems.- 1.11 References.- 2. Baseband and Modulated Signals.- 2.1 Introduction.- 2.2 Common, full-response, shaping function.- 2.2.1 Baseband signal.- 2.2.2 Modulated signal.- 2.2.3 Linear shift keying.- 2.2.3.1 Amplitude shift keying—double side band.- 2.2.3.2 ASK—single side band.- 2.2.3.3 ASK—vestigial side band.- 2.2.3.4 Quadrature amplitude shift keying.- 2.2.3.5 Offset quadrature amplitude shift keying.- 2.2.4 Phase shift keying.- 2.2.4.1 Differential phase shift keying.- 2.2.5 Frequency shift keying.- 2.2.5.1 Continuous phase frequency shift keying.- 2.2.5.2 FSK with noncontinuous phase.- 2.2.5.3 Multi-h frequency shift keying.- 2.2.5.4 Minimum shift keying.- 2.2.5.5 Equivalence of binary MSK and quaternary OQASK.- 2.2.5.6 Binary MSK as a form of DPSK.- 2.2.5.7 Equivalence of M-ary MSK and a modified OQASK.- 2.3 Nonoverlapping shaping function.- 2.3.1 Baseband signal.- 2.3.2 Modulated signal.- 2.3.3 LSK.- 2.3.4 PSK and FSK.- 2.3.5 MSK.- 2.4 Overlapping shaping function.- 2.4.1 Baseband signal.- 2.4.2 Modulated signal.- 2.4.3 LSK.- 2.4.4 PSK and FSK.- 2.4.5 MSK.- 2.5 Conclusions.- 2.6 Problems.- 2.7 References.- 3. Power Spectral Density (PSD) and Bandwidth.- 3.1 Introduction.- 3.2 PSD and bandwidth of modulated signal.- 3.3 PSD of complex envelope.- 3.3.1 Independent symbols.- 3.4 PSD of baseband signal.- 3.4.1 Common shaping function.- 3.5 PSD of LSK.- 3.6 Optimisation of shaping function.- 3.7 PSD of PSK.- 3.7.1 Shaping function of duration T.- 3.7.2 Common shaping function of duration T.- 3.7.3 Shaping function of duration 2T.- 3.7.4 Shaping function of duration KT.- 3.8 PSD of FSK.- 3.8.1 Shaping function of duration T.- 3.8.2 Shaping function of duration 2T.- 3.8.3 Shaping function of duration KT.- 3.9 The PSD of MSK.- 3.9.1 Binary MSK and common shaping function.- 3.9.2 Optimisation problem.- 3.9.3 General MSK.- 3.10 The PSD of QASK and OQASK with nonlinear bandpass filtering.- 3.10.1 Bandpass, memoryless nonlinearity.- 3.10.2 The PSD.- 3.10.3 PSD of hard-limited QASK.- 3.10.4 PSD of hard-limited OQASK.- 3.11 Filter bandwidth for digital radio.- 3.12 Summary.- 3.13 Problems.- 3.14 References.- 4. ASK Baseband System.- 4.1 Introduction.- 4.2 Optimal decision region and error probability.- 4.2.1 Maximum likelihood decision rule.- 4.2.2 Matched filters.- 4.2.3 Signal-to-noise ratio.- 4.3 Nyquist condition for no ISI.- 4.3.1 Intuitive approach.- 4.3.2 Analytic approach.- 4.3.3 Minimum bandwidth.- 4.3.4 Bandwidth not exceeding R.- 4.3.5 Raised cosine family.- 4.3.6 Spectral efficiency.- 4.3.7 Equalization.- 4.4 Effect of ISI.- 4.4.1 Properties of interference.- 4.4.2 Eye diagram.- 4.4.3 Computation of error probability.- 4.4.3.1 Worst-case bound.- 4.4.3.2 Bounds by finite number of terms.- 4.4.3.3 Taylor series expansion.- 4.4.3.4 Legendre series expansion.- 4.4.3.5 Quadrature formulas.- 4.4.3.6 Bounds to probabilty densities.- 4.4.3.7 Chernoff bound.- 4.4.3.8 Bounds and approximations of Jenq et al.- 4.4.4 Bounds in systems with dependent symbols.- 4.4.5 Applications of bounds to systems with Nyquist function response.- 4.5 System with NRZ, HS, and SP shaping functions.- 4.5.1 Derivation of system response, g(t).- 4.5.1.1 Causal filters.- 4.5.1.2 Filters with a finite number of distinct poles.- 4.5.1.3 Butterworth filters.- 4.5.2 Derivation of noise variance.- 4.5.2.1 Causal filter.- 4.5.2.2 Filters with a finite number of distinct poles.- 4.5.2.3 Butterworth filters.- 4.5.3 Error probability.- 4.6 Approximations of Nyquist functions.- 4.7 Summary.- 4.8 Problems.- 4.9 References.- 5. ASK Bandpass System.- 5.1 Introduction.- 5.2 Bandpass and Baseband ASK.- 5.3 Error probability.- 5.4 Error probability for ASK-DSB with nonsymmetric bandpass filter.- 5.5 Summary and conclusions.- 5.6 Problems.- 5.7 References.- 6. QASK and OQASK.- 6.1 Introduction.- 6.2 Condition of no interference.- 6.3 Systems with no interference.- 6.3.1 Rectangular constellation.- 6.3.2 Circular constellation.- 6.3.3 General constellation.- 6.4 Effect of interference in rectangular constellations (QASK, OQASK).- 6.4.1 Effect of QCI and ISI.- 6.4.1.1 System with Nyquist function response.- 6.4.1.2 System with Butterworth filters.- 6.4.2 Effect of ACI and ISI.- 6.4.2.1 System with Nyquist function response.- 6.4.2.2 System with distinct poles filters.- 6.4.2.3 MSK system with nonnegative impulse response filters.- 6.5 Effect of interference in circular constellations (PSK).- 6.5.1 Extension of the method of Jenq et al to circular constellation.- 6.5.2 System with Nyquist function response.- 6.6 Channel with flat and frequency selective fading.- 6.7 Summary.- 6.8 Problems.- 6.9 References.- 7. PSK and DPSK.- 7.1 Introduction.- 7.2 PSK.- 7.2.1 The pdf of phase and amplitude of a complex Gaussian random variable.- 7.2.2 Exact error probability.- 7.3 DPSK.- 7.3.1 Ideal DPSK.- 7.3.2 Bounds to error probability.- 7.4 Summary.- 7.5 Problems.- 7.6 References.- 8. FSK.- 8.1 Introduction.- 8.2 Coherent FSK.- 8.2.1 Orthogonal FSK.- 8.2.2 An upper bound to the error probability.- 8.2.3 Binary coherent FSK.- 8.3 Noncoherent FSK.- 8.3.1 No detector filters.- 8.3.2 With detector filter.- 8.4 FSK with discriminator detector.- 8.4.1 The PDF of instantaneous frequency.- 8.4.2 Binary FSK.- 8.4.3 Condition of no ISI.- 8.4.4 Effect of filter on FSK signal.- 8.5 FSK with discriminator and detector filter.- 8.5.1 Error probability for NRZ shaping functions.- 8.5.1.1 No intersymbol interference.- 8.5.1.2 With intersymbol interference.- 8.5.2 Error probability for split phase shaping function.- 8.6 Observation interval longer than T.- 8.7 Summary.- 8.8 Problems.- 8.9 References.- 9. Partial Response Signals.- 9.1 Introduction.- 9.2 Definition of PRS.- 9.3 Elimination of ISI by decision feedback.- 9.4 Elimination of ISI by precoding.- 9.5 Error monitoring.- 9.6 Summary.- 9.7 Problems.- 9.8 References.- 10. System Optimization.- 10.1 Introduction.- 10.2 Formulation of optimization problem.- 10.3 Optimal receiver and transmitter.- 10.3.1 Optimal receiver.- 10.3.2 Optimal transmitter.- 10.4 Minimization of the mean square error.- 10.4.1 Optimization of receiver.- 10.4.2 Optimization of receiver and transmitter.- 10.5 Summary.- 10.6 Problems.- 10.7 References.- 11. Equalization.- 11.1 Introduction.- 11.2 Definition of the problem.- 11.3 Structure of equalizers.- 11.3.1 Forward (nonrecursive) equalizer.- 11.3.2 Feedback (recursive) equalizer.- 11.3.3 Composite forward and feedback equalizers.- 11.3.4 Decision feedback equalizer.- 11.3.5 Composite forward and decision feedback equalizer.- 11.4 Minimum mean square error.- 11.4.1 Formal solution.- 11.4.2 Iterative solution.- 11.4.3 Practical solution.- 11.4.4 Automatic and adaptive equalization.- 11.4.5 Fast adaptive algorithm.- 11.4.6 Equalization of passband system.- 11.5 Zero-forcing equalizer.- 11.6 Nonlinear equalization.- 11.6.1 Small ISI.- 11.6.2 Large signal-to-noise ratio.- 11.7 Summary.- 11.8 Problems.- 11.9 References.- 12. Line Coding.- 12.1 Introduction.- 12.2 Binary codes.- 12.3 Linear ternary codes.- 12.4 Alphabetic codes.- 12.5 Nonalphabetic codes.- 12.6 Summary.- 12.7 Problems.- 12.8 References.- Commonly Used Functions and Symbols.- List of Abbreviations.