Research On Energy Efficient MAC Protocol In Wireless Sensor Networks

Wireless sensor networks (WSN) have broad applications and significant value, and have aroused the military, industry and academic attention. As we all known, they are a revolution of information sensing and collection method and one of the important technologies in 21 century. Medium Access Control (MAC) protocol, which is located between the physical layer and routing layer, is at data link layer, one of five parts in wireless sensor network system. Its primary responsibility is to control media access and establish a reliable communication link between nodes, and decide the wireless channel in wireless sensor networks. Among sensor nodes, MAC allocates the limited resources in wireless networks, in order that the adjacent nodes share channels and reduce or avoid conflicts, energy efficiency and throughput improve, and it is used to build the sensor network systems infrastructure. Therefore the sensor network sub-layer MAC protocol has a greater impact on wireless sensor networks, which is the key factor for highly efficient wireless sensor networks.In this thesis, we take energy efficient MAC layer and network efficiency as the theme, the main contribution of this dissertation is as follows:1.The dynamic adaptive modification of window based on traffic queue. The SMAC (Sensor MAC) uses the fixed contention window, when the traffic varies, it will easily lead to collision. We propose a novel adaptive dynamic tuning of the contention window MAC protocol, which is based on SMAC and uses three threshold parameters in order to improve the performance of networks.2. Simplified MAC layer communication mechanism. The SMAC sleeps, wakes up periodically and utilizes the RTS/CTS to contend for the channel, it also needs time synchronization. Although SMAC can decrease the energy consumption, its complex protocol as well results in many problems. On the contrast, this thesis will introduce a simple novel energy efficient MAC protocol,which can reduce the unnecessary consumption of the control package.3. Short preamble based on the Receiver-initiated MAC protocol. The Low Power Listening (LPL) MAC protocols generally use a long preamble sampling; this thesis sets up an alternative way based Receiver-initiated mechanism for the short preamble sampling, which improves in avoiding collision and scheduling.