Wireless Sensor Network (wsn) S - Improved Mac Protocol And Its Topology Correlation Studies

Wireless sensor network is a special kind of wireless self-organizing networks that has a very wide range of potential applications. The network channel allocation depends on the Medium Access Control (MAC) protocol, and the protocol is one of key protocols which ensure the high efficiency of communication in wireless sensor networks, and it has very important impact on channels utilization and the performance of the networks. Therefore, the study of the MAC protocol of wireless sensor network has great theoretical and practical significance.After the brief introduction of the current development status of the wireless sensor network at home and abroad and the classification of the MAC protocol in this dissertation, it discusses several main mechanism of S-MAC protocol. According to the features of wireless sensor network based on the sensor MAC(S-MAC), a new MAC protocol (Q-MAC protocol) is proposed, this protocol has two major improvements.First, this protocol change the fixed window value (CW) using in S-MAC protocol in terms of the improvement of random backoff mechanisms, it uses the adaptive contention window, when the node received data successfully or unsuccessfully, it uses two different window values, it can improve the performance of wireless sensor networks (WSN).And the improvement is effective by the NS simulation.Secondly, this new protocol has the queue mechanism, because the queue is the place to save the package, so we can forecast data flow according to the node’s length of queueing. When the node received data successfully, it can adjust the backoff window value adaptively according to the size of data flow, so it can improve the performance of the wireless sensor network. And the improvement is effective by the NS simulation.Then, this dissertation simply introduce the Linux operating system, NS simulator, nam, awk, Tcl and gnuplot, and we compare S-MAC and R-MAC protocol in star network and mesh network using these tools, and we make related graphics to show the experiment results.In the end of this dissertation, we conclude the whole dissertation and point out the further improvement.