A modified wireless token ring protocol for wireless sensor network

The Wireless Token Ring Protocol (WTRP) is a distributed medium access control (MAC) protocol which features self-organization, self-healing and no center, etc. It also guarantees fair node access and quality of service (QoS). Due to the enclosed nature of the ring structure, WTRP is not suitable for scenarios with rapid topology variations, but proved to be a valuable MAC protocol candidate for wireless sensor networks with relatively stable structure. This paper presents a modified WTRP with improvements in network structure expansion, energy saving and transport efficiency enhancement. The modified node joining mechanism expands the closed loop into node clusters, which enables better coverage; the sleeping scheme improves power efficiency; while dynamic token hold time adjusting enhances data throughput.