Opportunistic concurrency: A MAC protocol for wireless sensor networks

Traditional MAC protocols with CSMA often assume that a transmission must be deferred if the channel is busy, so they focus more on the optimization of serial transmission performance. Recent advances in physical layer like Message in Message (MIM), however, allows a receiver to reengage onto a stronger incoming signal from an ongoing transmission or interference, and thus shows the potential of parallel transmissions. Indeed, even if the channel is busy, a node still has opportunities to carry out a successful transmission. In this study, we propose Opportunistic Concurrency (OPC), a new MAC layer scheme, which enables sensor nodes to capture the opportunistic concurrency and carry out parallel transmissions instead of always waiting for a clear channel. Our experiments on a testbed consisting of 60 TelosB sensor motes identify the transmission opportunities in WSNs with OPC. Evaluation results show that OPC achieves a 17% reduction in packet latency, a 9.4% addition in throughput and a 10% reduction in power consumption compared with existing approaches.