A realistic relay selection scheme for cooperative MIMO networks

Most IoT devices are battery powered and have limited power supplies. To ensure communication between two nodes, multi-hop transmissions over relays could be used. However, this communication cannot be achieved if the Signal-to-Noise Ratio (SNR) at the destination does not reach a reasonable threshold. Different relay selection approaches have been proposed in the past. They assume that the battery discharge is linear, but the effectiveness of these schemes is not guaranteed when realistic non-linear battery models are considered. We propose a relay selection scheme by considering a realistic battery discharge model. We present an analytical study which demonstrates that, using cooperative relays nodes, offers a longer lifetime than using only one relay for each transmission round. Then, we derive an assignment scheme that attributes the transmission power for each relay in order to satisfy the SNR condition. The numerical results obtained demonstrate the effectiveness of our proposed solution.