An Energy-Efficient and Collision-Avoidance MAC Protocol with Pre-scheduling for Wireless Sensor Networks

In this paper, we propose energy efficient MAC protocols for data gathering tree structure. The basic concept of the proposed protocol is that it reduces traffic overloads in low depth nodes by introducing full sleep state for one frame. To maximize network performance, we only control traffic from non-relay nodes which are leaf nodes in the tree. We introduce a new superframe structure for pre-scheduling to alleviate contentions and packet collisions between children nodes. In addition, leaf nodes go into a full sleep mode for one superframe in heavy traffic loads by using control packets, which results in a considerable reduction of energy consumption at low depth nodes. Simulation results show the proposed protocol saves more energy and achieves better packet delivery ratio compared to the DMAC with a moderate increase of a latency performance.