Development And Simulation Of Wireless Sensor Network MAC Protocol Based On S-MAC

Wireless sensor network (WSN) is composed of massive, small and low-cost sensor nodes which are deployed in monitoring region, forming a multi-hop self-organized network system through wireless communication, the target of which is to cooperatively sense, collect and process the information of object in the coverage area, then send to the observer. WSN can be used in environment monitoring, military applications, medical treatment and so on.In WSN, medium access control (MAC) protocols determine the usage mode of wireless channel, allocate limited radio resource among sensor nodes and construct infrastructure. MAC protocols have a great influence on the WSN performance. MAC protocols of traditional wireless networks can't meet the design requirements for WSN, so they can't be used directly. Research on MAC protocols of WSN always attracts a lot of attention, which has great practical significance.Firstly, the structure of WSN, the existing MAC protocols and the keys of MAC protocols are introduced in this thesis. The thesis designs a MAC protocol for WSN, which adapts to special network application. S-MAC can achieve low duty cycle through periodical sleep, but the fixed duty cycle of S-MAC increases latency, so the thesis designs a dynamic duty cycle which can adjust duty cycle of nodes in time, send several data packets in a duty cycle to reduce latency and increase throughput. Meanwhile, in order to avoid nodes collision, the thesis designs backoff strategy that adjusts CW according to data traffic, achieve quick access and low collision. The thesis also presents a maintenance scheme which can detect link through periodically updating neighbor information.Afterwards, the thesis implements the improved protocol based on NS-2 and designs a simulation experiment. In this thesis, AWK program methods are used to accomplish statistical analysis of trace file data extraction and three main attributes (energy, latency, and throughput) of network. The simulation results show that, in contrast with S-MAC and 802.11 MAC, the improved S-MAC protocol improves energy savings, the mean throughput, and network update operation, etc. It is quite useful for network protocol research.Finally the thesis draws conclusions by summarizing the main contributions of the research and by presenting directions for future work.