Research Of High Efficient Mac Protocol In Wireless Sensor Networks

Wireless sensor networks (WSN) have broad applications and significant value, and have aroused the industry and academic attention,it is one of the most important technologies in 21 century. Medium Access Control (MAC) protocol, which is a part of data link layer in wireless sensor network system. Its primary responsibility is to allocate the limited resources in wireless networks,establish reliable communication links between nodes, and it is used to build the sensor network systems infrastructure.MAC protocol in current research is divided into two categories, the sender-initiated and the receiver-initiated. The sender-initiated protocol using synchronization or the preamble to establish their connection, has problems are that the cost of using the synchronization is too high, and the large number of long preambles greatly reduces the network utilization.The receiver-initiated protocol (RI-MAC) use the message periodically send by the receiver to establish a connection with the sender, it can solve the problems of the sender-initiated protocol, but in the RI-MAC protocol , the waiting time of the sender is greatly increased,and then it delays the transfer and increases the energy-consuming of the sender.This thesis based on the current research of the MAC protocol, made full use of the benefits of the sender-initiated and the receiver-initiated protocol,propose a new duty cycle MAC protocol,called Initiator-convertible and Locally synchronized MAC Protocol (IL-MAC). This protocol reduced the waiting time of the sender and receiver to establish a connection; By setting the node's queue length threshold, The node according to the urgency of each transmission, decide to use the sender or the receiver start the way to transfer,its solve the problems of the above two types of protocols.In this thesis,the performance of the novel protocol is evaluated and compared with RI-MAC in NS2 by using three types of networks:clique network, grid network and random network.The result shows, IL-MAC in low-load conditions have advantages over the RI-MAC,then in the high-load conditions the advantages are being more obviousily.