Abstract: Since the most of existing MAC protocols in wireless sensor networks do not support any priority scheme,this paper proposed an improved scheme of the existing S-MAC(sensor MAC) protocol, say, DC}MAC(Diffserv-based Qo}aware MAC). The main idea is that, based on Differentiated Services, an additional channel listening time was introduced for high priority data. As a result, compared to low priority data, data with high priority can achieve much more chance to be delivered, and the packet transmission latency of high priority data is reduced significantly as well. Our mathematical analysis demonstrates that, using the proposed D呀MAC, the transmission quality of high priority dato over wireless sensor networks is effectively improved, in terms of achieved throughput, average service delay, and so on.

Key words: Wireless sensor networks,Diffserv,MAC