Accurate and efficient analysis of wireless digital communication systems in multiuser and multipath fading environments

by Annamalai, Annamalai

Testirnonies of " wireless catching up with wireline" have begun. However, the nonstationary and hostile nature of the wireless channel impose the greatest tfireat to reliable data transmission over wireless links. The performance of a digital modulation scherne is degraded by many transmission impainnents including fading, delay spread, cochannel interference and noise. Two powerful techniques for improving the quality of service over the wireless network are investigated: diversity reception and adaptive error control schemes. Owing to the growing interest in wireless co~~llllunications, the importance of exact theoretical analysis of such systems cannot be understated. In light of these considerations, this dissertation focuses on accurate and efficient analysis of wireless digital communication systems in multiuser and multipath fading environments. The evaluation of emor probabilities in digital communication systems is often arnenable to calculating a generic error probability of the form Pr {XI O 1, where X is a random variable whose probability distribution is known. We advocate a simple numerical approach based on the Fourier or Laplace inversion formulas and Gauss-Chebychev quadratures (GCQ) for computing this error probability. Using this result, and by formulating the outage probability of cellular mobile radio networks in the fkamework of statistical decisioa theory, we can uni@ the outage performance analysis for cellular mobile radio systems in generalized fading channels without iiiposing any restrictions on the desired signal and interferers statistics. Next, we develop two unified analytical fiameworks for evaluating the bit or syrnbol error probability (SER) of a broad class of coherent, differentially coherent and noncoherent digital communication systems with diversity reception in generalized fading channels. The exact SER is mostly expressed in terms of a single finite-range integral, and in some cases in the form of double finite-range integrals. Viially "exact" closed-form expressions (in tenns of a rapidly converging series) are also derived. This offers a convenient method to perform a comprehensive study of ail common diversity co~bining techniques (maximal-ratio combining (MRC), equal-gain combining (EGC), selection combining (SDC) and switched combining (SWC)) with different modulation formats in a myriad of fading scenarios. In particular, our unified approach based on characteristic function (CHF) method allows us to uni@ the above problem in a single common framework. Nevertheless, the moment generating fimction (MGF) method often yields a