Study and Analysis of Two-Way AF Relaying Based Cooperative Diversity System

Abstract

In wireless communication system, the presence of electromagnetic waves cause multipath propagation of wireless signals and results in variation of received signal strength as a function of transceiver location, transceiver motion and frequency. These variations produce wireless channel variations, known as fading. Different diversity techniques are used to mitigate and exploit multipath fading to improve the performance of wireless communication system. One such technique is cooperative diversity which reduces variation in signal attenuation which in turn controls interference and fading. The key concept of this method is to send multiple copies of the signal and then adding them at the receiver and the receiver decodes the information received from different nodes which act as virtual antennas, this increases the signal to noise ratio of the system. Cooperative diversity prevents the size limitations and gives spatial diversity in wireless applications like ad hoc, cellular and sensor networks. In conventional cooperative diversity networks, this uses half-duplex fashion in which sending one information symbol from the source to destination terminal needs two channels. This result in a loss in spectral efficiency, to improve this two way relaying is proposed. In this technique in first phase the multiple access (MA) phase, two source nodes simultaneously transmit their information to relay and then the second phase the broadcast (BC) phase, in which relay broadcasts the received signal to the two source nodes. Two way amplify and forward (AF) relaying has been a promising technique in future wireless communication because it has a capability to achieve high coverage and spectral efficiency for half duplexer lay systems. It provides large coverage area, high spectral efficiency and high date rate even in hostile environments and lands. The objective of this dissertation is to present a holistic study and analysis of the performance of a two way amplify and forward cooperative communication system under different fading channel conditions. The performance evaluation is done by analysing different mathematical expressions and analytical as well as Monte Carlo simulation are done to achieve performance curves for different modulation schemes over a range of signal-to-noise ratios for various values of fading parameter.