FlexiMAC: A flexible TDMA-based MAC protocol for fault-tolerant and energy-efficient wireless sensor networks

We propose FlexiMAC, a novel TDMA-based protocol for efficient data gathering in wireless sensor networks that provides end-to-end guarantees on data delivery: throughput, fair access, and robust self-healing, whilst also respecting the severe energy and memory constraints of wireless sensor networks. Flex-iMAC achieves this balance through a synchronized and flexible slot structure in which nodes in the network can build, modify, or extend their scheduled number of slots during execution, based on their local information. This scheme allows FlexiMAC to be strongly fault tolerant and highly energy efficient. FlexiMAC further minimizes energy by selecting optimum node transmission power for a given topology. FlexiMAC is scalable for large number of nodes because it allows communication slots to be reused by nodes outside each others´ interference range, and its depth-first-search schedule minimizes buffering. Simulations show that FlexiMAC ensures energy efficiency and is robust to network dynamics (faults such as dropped packets, nodes joining or leaving the network) under various network configurations.