An Energy-Efficient MAC Protocol Based on Routing Information for Wireless Sensor Networks

In wireless sensor networks, the most significant traffic pattern is data gathering from sensor nodes to sink through multihop paths forming a tree structure. This paper presents an energy-efficient MAC protocol based on routing information, EBRI-MAC, designed for such traffic pattern. In EBRI-MAC, an idea of clustering based on data deliveries on the tree is proposed, in which a parent node and its child nodes form a virtual cluster. Based on this structure, a medium access scheme of chain-invitation combined CSMA/CA and a scheme of active/sleep schedule synchronization within each virtual cluster are designed in order to save energy. Considering the major sources of energy waste, the parameter n^E is defined to evaluate the energy efficiency, and the theoretical analysis has been performed. By comparison results through ns-2 simulation, it has been verified that EBRI-MAC can win better energy-efficiency than IEEE802.11 DCF and S-MAC under the traffic pattern of each node being time-correlated.