Energy Harvesting In Multi-Relay Based Wireless Networks

Energy harvesting or energy scavenging is the process to generate electrical energy from environmental energy sources. There exists a variety of energy sources such as solar energy, wind energy and thermal energy. Energy harvesting(EH) based relay networks has gained substantial attention of researchers both from academia and industry because of its potential to overcome the problems of path-loss, fading, coverage and capacity by adopting spatial multiplexing and diversity gain to improve the quality and performance of wireless networks. By joining the EH with relaying provides the solutions of all problems described above. EH provides ultimate solution to counter greenhouse impact and help to reduce the emission of CO2 which has become a critical problem. EH improves the life time of battery dependent networks where replacement or recharging of battery is crucial such as sensor implanted in human body, sensor in buildings and in nuclear radiation monitoring systems.Energy harvesting utilizes the ambient radio frequency signals from the environment to transfer data. Simultaneous wireless information and power transfer(SWIPT) is a key technology that has distinguished characteristic and provide solution for energy efficiency,better spectrum utilization and extension to coverage of more area in wireless networks. It has become one of the fastest growing research direction in the communication industry. In order to satisfy the exponential growth of demand, wireless service providers are striving to improve the communication systems so that higher data rate wireless transmission can be supported. Relay based wireless network has ability to extend the coverage range with reduced infrastructure and deployment costs.This dissertation deals with SWIPT and multi-relay selection(MRS). The analysis of the considered system is based on information theoretical performance limits, energy efficiency and achievable rates. In this thesis, we developed SWIPT with amplify-and-forward(AF) relaying strategy under multi-relay selection criterion with different power distribution. We consider the channel variance from source node to relay and relay to destination suffers different channel behaviour,thus each relay has different channel variance and power allocation. We develop an algorithm for optimum relay selection subset N from available M relays. Simulation and numerical results demonstrate that our proposed scheme is optimum in terms of energy efficiency and system outage probability,the complexity is reduced under defined parameters.