Study and Analysis of Cooperative Diversity Communication Systems Under Various Fading Channel Environments

Abstract

The propagation of a radio wave through the wireless medium is affected by a host of impairments. Fading is one such phenomenon which has been an area of significant research for the evaluation of the performance of a digital communication system. Based on the nature of the radio propagation medium, a variety of statistical modelsare used to characterize the fading of a wireless signal. Diversity is one of the prime techniques to deal with the severity induced in a signal transmitted over a fading channel. The goal for a system designer is to arrive at a unified set of mathematical models characterized by diversity combining schemes. Spatial diversity is a well known method to generate independent communication paths between the sender and the receiver through the use of multiple antennas at the transmitter and/or receiver. A recent method to achieve spatial diversity is the cooperative diversity communication. It makes use of the mobile users in a network to relay the original source signal to the destination which creates a virtual form of multiple-input and multiple-output antenna array system. In a cooperative communication system, it is possible to deter the effects of shadowing and deep fading both of which severely affect the quality of signal transmitted in a wireless network. The mobile user which acts as the relay node processes the original signal received from the source and retransmits it to the destination. The resultant signal at the receiver is analyzed using different parameters to bring improvement in the overall performance of the communication system. The objective of this dissertation is to present a holistic analysis of the performance of a cooperative communication system under different fading channel conditions. The performance evaluation is done analytically as well as through Monte Carlo simulation to achieve performance curves for a variety of modulation schemes over a range of signal-to-noise ratios.