Load-aware energy-efficient medium access control for Wireless Sensor Networks

In wireless sensor networks, sensors are usually battery-powered. Therefore, it is essential to reduce energy consumption to prolong network lifetime. In traditional power saving MAC protocols, such as IEEE 802.11 Power Saving Mode and SMAC, sensor nodes must wake up at every beacon interval to check if they are involved in any transmission. Such a fixed active/sleep mechanism fails to adjust a sensor node’s sleep duration based on its traffic load. Thus, these protocols suffer from either higher energy consumption or higher latency. In this paper, we propose a Load-aware Energy-efficient MAC protocol (LE-MAC) which utilizes fuzzy control and the quorum concept. The LE-MAC protocol utilizes fuzzy control to dynamically adjust the active/sleep ratio of each sensor node. The duration for a node to stay in sleep mode is increased to conserve energy when its traffic load is light. On the contrary, the ratio of operating in active mode is increased to reduce transmission latency as traffic load is getting heavier. The quorum concept is adopted to guarantee that two sensor nodes with different active/sleep ratios can meet and communicate with each other. Simulation results verify that our LE-MAC can adapt to various network traffic loads. Furthermore, LE-MAC achieves significant performance improvements in energy consumption, transmission successful ratio, and transmission delay.