A Research On Energy-Saving Mechanism Of MAC Protocol For Wireless Sensor Networks

Wireless sensor networks are the new wireless networks, have broadly application foreground. In wireless sensor networks, medium access control (MAC) protocol decides the use mode of wireless channel, assigns limited wireless traffic sources, constructs bottom cadre of wireless sensor networks system, influences obviously the networks performance. Traditional MAC protocol of wireless networks does not meet the requirement of sensor networks for the limited energy, can not be directly applied. So the research on wireless sensor networks MAC protocol becomes popularity, and has very important practical value.Firstly, this thesis introduces the research background, analyzes the MAC protocol existed and their principle of design, the reason for major energy consumption, and the performance of the networks. Secondly, this thesis designs an adaptive MAC protocol based on S-MAC, and evaluates its performance via simulation. S-MAC is presented aiming at energy saving and self-organizing of wireless sensor networks, mainly gains low duty cycle through cycle sleep. However, S-MAC increases traffic delay because of the fixed duty cycle. This thesis designs a dynamic duty cycle adjustment mechanism. It can adjust sleeping frequency, duty cycle with traffic exchange of wireless sensor networks, decreases latency, and promotes the throughput of networks. The thesis presents an analysis method of the average time delay. it can influences the duty cycle. Aiming at lessening the cost of control, thesis decreases the length of control frame, so save the time of sending data.Lastly, this thesis simulates the new MAC protocol using the NS2, adopts AWK to draw the data from the trace file, analyze the two index of performance (energy, time delay) of networks by statistics. The simulation result shows that the MAC protocol we presented can improve the performance in both energy saving and time delay compared with S-MAC and IEEE 802.11 MAC. This MAC protocol is of practical value for communication of wireless networks.