EC-MAC: A Cross-Layer Communication Protocol for Dynamic Collaboration in Sensor Networks

In numerous sensor network applications, a group of nodes surrounding an event (forming an active region) must collaborate to collect locally generated data, reliably and efficiently. Active regions are often characterized by intense data transfer, packet collisions and congestion, resulting in significant network performance loss. Previous studies dealt these scenarios either at the application or network layers, where potential performance gains at the MAC layer were not considered. In this paper, a cross-layer communication protocol Event-Centric MAC (EC-MAC) is introduced in which the channel access time is divided into two intervals. During slot reservation interval, all nodes within an active region collaborate to construct a Transmit/Receive schedule on-the-fly. Once the schedule is in place, data forwarding is performed during the data transmission interval towards a designated root node. By allowing contention-free channel access, EC-MAC outperforms fully awake and LPL-based MAC protocols in terms of both energy efficiency and data throughput.