Simultaneous Energy Harvesting and Information Processing in Wireless Communications Using Multiple Relays with Multiple Antennas Considering Various Locations of Relays

Wireless networks suffer from battery discharging specially in cooperative communications, where multiple energy constrained relays are used. To overcome this problem, energy harvesting from RF signals is used to charge the node battery. These intermediate nodes have the ability to harvest energy from the source signal and use the harvested energy to transmit information to the destination. In fact, the node tries to harvest energy and then transmit the data to destination. Division of energy harvesting and data transmission periods can be done in two different protocols, namely time switching based relaying protocol (TSR) and power splitting based relaying protocol (PSR). These two protocols can also be applied in delay-limited and delay-tolerant transmission systems. The previous works have assumed a single relay for energy harvesting; However, in this paper, the proposed method is concentrated on improving the outage probability and throughput using multiple antennas in each relay node instead of using single antenna. Also the optimum location of multiple relays is discussed and its effect on throughput of the system is mainly considered. According to our simulation results, when multi-antenna relays are used, ability of energy harvesting is increased and thus system performance will be improved to a great extent. MRC selection relay scheme is used when the destination chooses a group of relays and antennas satisfying the required SNR.