EVAM-MAC: An Event Based Medium Access Control for Wireless sensor Networks with Multihop Support

As wireless sensor network applications are becoming more complex, the need for a versatile medium access control that is able to deliver high data rates is essential. In event-based systems, sensor nodes spend most of their time at sleep state waiting for an event to occur. When an event is detected, sensor nodes experience a short abrupt period of high data contention where the data packets are large in size. As the number of sensor nodes per-hop increases, the contention generated will lower the throughput, increase latency and deteriorate the application’s performance. EVAM-MAC is a medium access control that is tailored specifically for event-based systems. EVAM-MAC shifts the contention generated by multiple sensor nodes trying to deliver the collected measurements to the control phase. Furthermore, it arranges data transfer in a contention free environment by dynamically creating a TDMA-like schedule without global synchronization or global slot assignments. EVAM-MAC offers a platform of configurable operations that can be programmed prior to deployment. The protocol is simulated with NS2 and compared with an implementation of S-MAC and 802.11 for multiple scenarios where EVAM-MAC presented its superiority in throughput, Latency and Energy consumption.