Improvement And Realization Of Wireless Sensor Network S-mac Protocol

Wireless sensor networks (WSN) is composed of massive 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, medical treatment and so on.Medium Access control (MAC) protocol is allocated at the low level of WSN protocols, which is mainly used to control sensor nodes sharing communication medium fairly. MAC protocols have a great influence on the WSN's performance. Different with the traditional wireless networks, improving energy-efficiency and scalability are the major goals of MAC protocol design in WSN. It is very important to design and implement MAC protocols to meet the requirements of WSN.The structure of WSN, the requirements of MAC protocols and the existing MAC protocols are introduced in this thesis, and the key factors of energy consumption in WSN are also discussed. S-MAC is introduced and analyzed in this thesis, and a new MAC protocol for WSN is put forward through improving the disadvantage of S-MAC. The fairness of the contention is improved by using hierarchical-EIED backoff algorithm, and the energy consumption in idle listen state is reduced by a new adaptive listen strategy which uses route information. A new GSA algorithm is also put forward to reduce the complexity by using route information, and an adaptive handshake strategy is used to improve the transmission efficiency of the short messages.Afterwards, the improved protocol is implemented on our own platform, including the driver, PHY protocol and MAC protocol. Several experiments are designed to testify the system. According to the results, the protocol meets the requirements for low data rate application of WSN. The performance of energy-efficiency and scalability is good. The protocol achived the goal of design, and it is useful for next step research of the network protocol.