FlexiTP: A Flexible-Schedule-Based TDMA Protocol for Fault-Tolerant and Energy-Efficient Wireless Sensor Networks

摘要

FlexiTP is a novel TDMA protocol that offers a synchronized and loose slot structure. Nodes in the network can build, modify, or extend their scheduled number of slots during execution, based on their local information. Nodes wake up for their scheduled slots, otherwise switch into power-saving sleep mode. This flexible schedule allows FlexiTP to be strongly fault tolerant and highly energy efficient. FlexiTP is scalable for large number of nodes because its depth-first-search schedule minimizes buffering and it allows communication slots to be reused by nodes outside each others'' interference range. Hence, the overall scheme of FlexiTP 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. Simulations in ns-2 show that FlexiTP ensures energy-efficiency and is robust to network dynamics (faults such as dropped packets, nodes joining or leaving the network) under various network configurations (network topology and network density), providing an efficient solution for data gathering applications. Furthermore, under high contention, FlexiTP outperforms Z-MAC in the average packet delay, energy saving and throughput.