Research On Channel Access Technology In Wireless Sensor Networks

Wireless Sensor networks (WSN), which is made by the convergence of sensor, nested computation, networks and wireless communication technologies, is a novel technology about acquiring and processing information. It is a late-model wireless networks of infrastructureless network and can be used for testing, sensing, collecting and processing information of monitored objects. WSN is a new research area of computer science and technology and has a wide application future. Both academic and industries are very interested in it.Designing medium access control protocol for WSN is the main part of this dissertation. The number of sensor node in WSN is numerous and single node is extraordinarily limited in resource. The primary target of designing MAC protocol for WSN is to reduce the overall energy dissipated in the network and to maximize the network lifetime. The author analyzed and compared some MAC protocols that proposed by overseas researchers and assimilated excellence ideas among them and designed a new MAC protocol for WSN—Adaptive Pattern Sensor MAC protocol.SMAC is a typical MAC protocol for WSN that adopt sleep-wakeup mechanism. In SMAC, the sensor nodes are put to sleep periodically to save energy. As the duty cycle is fixed in such protocol, the network throughput can degrade under heavy traffic, while under light loads, unwanted energy consumption can occur. In the proposed AP-MAC protocol, instead of having fixed sleep-wakeups, the sleep-wakeup schedules of the sensor nodes are adaptively determined. The schedules are decided based on a node's own traffic and that of its neighbors. Our analytical and simulative experimental results show that in comparison with SMAC and TMAC, AP-SMAC achieves more power savings under light lodes, and higher throughput under heavier traffic loads. We can conclude from the results that the AP-SMAC protocol achieves its design goal.