Improve The MAC Protocol Of IEEE802.15.4Beacon Mode

The wireless sensor network now is the focus of the industry and academia, andhas a very broad application prospects in many fields. IEEE802.15.4standarddeveloped specifically for the low-speed wireless personal area networks, particularlysuitable for wireless sensor networks，because of it’s characteristics of low energyconsumption, low transmission rate and low-cost. In many applications of wirelesssensor networks, some real-time business have strict delay requirements.There are two modes in IEEE802.15.4MAC protocol, beacon mode andnon-beacon mode. In order to meet the low-latency requirement of real-time business,the node can apply GTS to transmit real-time business in beacon mode. This methodhas a good effect in the case of not heavy network load. However, GTS request framemust be sent by using the CSMA/CA mechanism to compete to access channel assame as ordinary data frame. GTS request frame has a large transmission delay in thecase of heavy network load. It affects the transmission of real-time services.To solve the problem, this paper designs a GTS request mechanism based on theindependent GTS request window, and adds an adaptive duty-cycle algorithm in theimproved MAC protocol. The improved MAC protocol not only has a largeimprovement in the performance of real-time business, but also has a goodperformance of non-real-time business.