Performance Analysis of Wireless Communication Systems over Composite Fading Channels

Abstract

Wireless communication differs from wired one in the way signal propagates through the channel. Signal while travelling from transmitter to receiver terminal follows random propagation paths which lead to multi path components in case of wireless channel. Due to its inability to distinguish between different multi path components a simple receiver terminal add them up which leads to interference. This interference can be either destructive or constructive depending upon the phase angle of the multi path components. Phase information of multi path component depends on the run length which is a function of position of transmitter, receiver, and interacting objects. Therefore with change in their position interference changes leading to fluctuation in amplitude of total signal and this phenomenon is known as multipath fading. As the variation of signal occurs over a very small distance, of the order of wavelength of signal multipath fading is also known as small scale fading. When the obstacles lying in between transmitter and receiver absorb power it results in shadowing phenomenon. In realistic scenario received signal over a wireless channel is characterized by the joint effect of both multipath fading and shadowing which is modeled with the help of composite fading channel. This factor motivates us to carry out the performance analysis over different composite fading models. First of all performance analysis of shadowed Rice composite fading model has been carried out by deriving the analytical expressions for average symbol error probability as well as average probability of detection under two different fade mitigation methods. The derived PD expression is utilized to analyze the performance of cooperative system assuming erroneous feedback channel. Analysis of optimization of detection threshold as well as number of cognitive users to minimize the total error rate is also carried out. newline newline newline