Energy evaluation of a cooperative and duty-cycled ARQ scheme for Machine-to-Machine communications with shadowed links

The design of energy-efficient communication strategies is needed to extend the lifetime of Machine-to-Machine low power devices operating in realistic wireless fading and shadowing channels. In this paper, we assess the suitability of using cooperative and duty-cycled retransmissions (CDC-ARQ) in realistic low power networks to improve their energy-efficiency. A CDC-ARQ scheme achieves this goal by maintaining two interchangeable wireless links towards any intended destination and using the currently optimal link in an opportunistic manner. We perform comprehensive performance evaluation using the ns-3 simulator to verify a theoretical framework fitted to the reference IEEE 802.15.4e protocol and its cooperative extension. The ns-3 simulation outcomes confirm prior theoretical findings and indicate optimal operating regions with minimum energy consumption for the shadowed relay system under consideration. We establish that a significant energy improvement can be achieved in a typical three-node scenario when a duty-cycled opportunistic cooperative relaying protocol is used instead of a fixed two-hop relaying system.