Abstract: Considering that most of the existing MAC protocols in wireless sensor networks do not support any priority scheme,this paper proposed a novel,Diffserv-based low-delay MAC mechanism(DLl)MAC)，on the basis of the existing DW-MAC protocol. I}he main idea is that, by introducing differentiated services, the high priority data chooses smaller back-off window, so that it can achieve much more chance to be delivered, and its packet transmission latency and energy consumption can be reduced significantly compared with low priority data. On the other hand,a Markov chain model was designed in this work, to analyze and evaluate the mechanism performance. Our analytical analyses show that the proposed DLl)MAC can effectively make the high priority data achieve higher QoS over the low priority data, and achieve much lower transmission latency than traditional MAC protocol as well, which is adequate to serve delay-sensi- tivc data flow.

Key words: WSNs,MAC,Diffserv service,Markov chain,Low-delay