PSO based power allocation for single and multi relay AF cooperative network

摘要

Wireless channels are generally suffering from fading. Diversity is the effective way to combat fading in wireless channels. But, the ultimate aim of diversity is to allow multiple antennas into the environment. Due to size and hardware complexity, many wireless devices are limited to one antenna. Cooperative communication is a new class of diversity, it allows single antenna users into a multi user environment to share their antennas and create virtual multiple antennas. In cooperative communication, the information is transmitted with the help of neighboring nodes, which are called relays. Cooperative diversity is based on different relaying schemes such as amplify-and-forward, decode-and-forward and coded cooperation. Cooperative transmission using relay gives better performance compared to direct transmission between the source and destination. The system performance enhances as the number of relays in the network increases and in addition the diversity order also increased. Power allocation is one of the major issues in a wireless cooperative communication for enhancing the system performance. In this work, a single and multi relay cooperative network is considered using amplify-and-forward relaying scheme. Considering the perfect channel state information (CSI), allocating power to source and relay using Particle Swarm Optimization (PSO) with minimizing as a constraint. The PSO algorithm maintains a group of particles, where each particle in the group gives a possible solution. PSO gives the best optimum value for a given problem by using objective function. Hence the implemented scheme of PSO base power allocation in cooperative network enhances the system performance.