Research And Implementation Of MAC Protocols In Wireless Sensor Networks

Wireless sensor networks is composed of a large number of distributed sensor nodes that are densely deployed either inside the phenomenon or very close to it. These sensor nodes organize themselves into a multi-hop wireless network and cooperate to deliver collecting data to sink nodes. As sensor nodes are likely to be battery powered, and it is often very difficult to change or recharge batteries for these nodes, reducing energy consumption is the primary goal in wireless sensor networks design. This thesis is based on the National Development and Reform Commission CNGI R&D/industrialization and experimentation/application demonstrationproject—"IPv6 wireless sensor networks nodes", focusing on MAC protocol of wireless sensor networks.The first part of this article gives an overview of research on WSN, including its origin, development, character and application.Based on the analysis of business characteristics of the WSN, the design demand and consideration factors of MAC protocol of WSN were put forward.In the second part of this article,there is a research on several typical MAC protocols and dormancy mechanism, followed by the analysis of typical MAC protocols and the main factors that causes energy waste of MAC protocols, the key technology to design MAC protocols of WSN is brought forward.In the third part of the article,under the research of typical MAC protocol, based on the requirement of the project and restrict of practical condition, aiming at the problems in the implementation of S-MAC protocol, an improved S-MAC protocol is designed. The improved S-MAC protocol is improved performance effectivelly.The last two parts of this article is stressing a production of implementation and testing of improved protocol in the project of "IPv6 wireless sensor network nodes". The implementation of simple and effective improved S-MAC protocol on self-made IPv6 wireless sensor networks nodes is divided into two parts: one is establishing and maintain of dormancy cycle,the other is data communication process. The debbuging of improved S-MAC protocol function module is completed on hardware platform using presetted information, tracking programme and serial listening programme. Make statistics of collision probability, package lost rate and time delay in different business interval,to comlete the function testing of MAC layer and the contrast to S-MAC protocol. The testing result indicates that the appilication programmes which are loaded on MAC layer module can run smoothly after system debugging, improved S-MAC protocol preferably eases the collision probability, reduce package lost rate and time delay, and it has excellent energy efficiency.