Wireless digital communications on fading channels with diversity and interference

Transmission in wireless communication systems is carried out in a radio propagation environment. The radio propagation environment places fundamental limitations on the performance of wireless communication systems. Mainly, transmission is subjected to three major sources of degradation. These are fading, shadowing, and cochannel interference. Hence, in order to improve the reliability of communication and to increase the spectrum efficiency of wireless communication systems, some measures have to be employed to mitigate the effects of these degradations.;In this thesis, we investigate the use of different diversity methods to mitigate the effects of fading, shadowing, and cochannel interference. Mainly, we will present analytical methods and algorithms that can be used to assess the performances of digital communications employing diversity combining and operating in the presence of cochannel interference on wireless fading channels.;The goal of this thesis is to provide analytical tools and results that can be used by system designers and engineers to determine and compare the performances of different methods that can be used to mitigate the performance impairments introduced by the radio propagation environment and by cochannel interference. Of the same importance, or maybe more important, is the fact that these tools can be used for a wide range of fading conditions and environments, and are not limited to a specific fading environment.;This thesis is divided into three parts. In the first part (chapter 2-chapter 5), we analyze the performances of different diversity techniques on frequency non-selective fading channels. The use of microdiversity to mitigate the effects of fading and macrodiversity to alleviate the effects of shadowing are investigated in detail. Both the Nakagami and the Ricean fading models are used. The second part of this thesis (chapter 6-chapter 8) is devoted to analyzing the effects of cochannel interference on the performances and on the design of frequency reuse systems under the effects of different fading and shadowing conditions, and using diversity combining schemes. In the third part of this thesis (chapter 9), we analyze the performance of MDPSK on frequency-selective Rayleigh fading, lognormal shadowed channels with diversity combining.