Research On Media Access Control In Wireless Sensor Network Based On UWB

Media access control mechanism in wireless network is used to coordinate the mobile nodes to make use of the wireless resource efficiently, support flexible multiplex control and QoS management. The object of wireless media access control technology is to improve the system throughput, ensure fairness and reliability and reduce access delay. Wireless sensor network is composed of a large number of sensor nodes, which are random deployed and self-organized in monitor area. UWB (Ultra-WideBand) is a new communication technology in short-distance wireless communications, which is especially applicable to wireless sensor networks for its high immunity to multi-path distortion, low power spectrum density of transmitted signals, low detected ability, low system complexity and high location accuracy.First, based on the basic principle of media access control, several types of media access control mechanisms are compared and analyzed.In chapter 3 of this paper, the IEEE 802.15.4 media access control protocol which is considered as one of the most suitable protocols for use in wireless sensor network is studied in detail. We set up Markov model and deduce the probability of the first CCA and the second CCA firstly, then we get the throughout of network and conclude that throughout is related with data length and BEmin.Chapter 4 is divided into two parts. In the first part, we analyze the capabilities of IEEE 802.15.4 MAC protocol in UWB system and in narrowband system respectively. UWB system is super than narrowband system, but it doesn't attain to higher throughout ratio. Then we properly modify the IEEE 802.15.4 MAC protocol's parameters, and discover that increasing the ratio of valid data in the super frame can increase the throughout of network. In the second part, we propose a new MAC protocol based on position sensing, which turn off a part of redundancy node and choose the minimum energy-consume path by the UWB accurate position technique to attain the extension of network life. According to the comparison with IEEE 802.15.4 MAC protocol, the new protocol improves the energy consumption greatly while sacrificing a little latency.At last, the paper is summarized. The wireless media access control in ultra-wideband sensor network and power saving mechanism are reviewed, and then the research orientation related to these fields are also introduced.