A practical cross layer cooperative MAC framework for WSNs

The evolving Internet of Things is expected to enable realization of wireless sensor networks (WSNs) for a variety of applications. Energy efficiency and reliability are the key criteria for the success of WSNs of IoT. In this article, a cooperative medium access control (MAC) framework is proposed for improving the performance and energy efficiency of WSNs, while satisfying a given reliability constraint. The energy-reliability trade off is achieved through a relay selection and power assignment algorithm, which is implemented within the COMAC cooperative MAC protocol that enables the coordination of candidate relays, calculation of the decision metrics, selection and actuation of the relay nodes with optimal power levels for cooperation. The proposed cross-layer MAC framework is evaluated in terms of energy costs as well as network performance metrics, in terms of throughput, delay and overhead. It is shown that the network throughput can be improved significantly, while the energy consumption is reduced by at least two orders of magnitude as compared to standard Zigbee WSNs, at negligibly small overhead and computational costs.