Research Of Link Reliability On ZigBee Wireless Sensor Network

Wireless sensor network is a comprehensive intelligent information system which integrates information collecting, transmitting and processing. Synthesized by many technologies, such as MEMS, sensor, embedded computing, modern network, wireless communication, distributed information processing, etc, the system utilizes various integrated micro-sensors to monitor, sense and collect real-time information of environment or objects and sends the result to terminal through the way of wireless, self-organizing and multi-hop.For the interconnecting of physical world, computer world and human society, it has broad application prospects in military defense, industry and agriculture, city management, environment monitoring, disaster relief, remote control of dangerous field and so on.As an emerging wireless communication technology, ZigBee draws more and more concerns by the virtual of low cost and low power consumption. Because of these advantages, the research on Zigbee technology has been put on agenda. The paper firstly presents and analyzes IEEE802.15.4/ZigBee standard, then proposes link reliability problems during data transmission based on application environment of wireless network, and finally brings forward relevant solutions and strategies.Due to the limited distance of transmission, communication of wireless sensor network is usually accomplished with multiple middle nodes. The stochastic movement of some nodes could cause worse link qualiy, even link disconnection which influences reliability of data transmission. The problem would also occur when energy is insufficient. Focused on these issues, a link prediction and link switching strategy is proposed based on LQI. Additionally, according to battery's discharge characteristics and method of judging terminal voltage, another strategy of link prediction and switching is presented based on critical energy.In link switching based on LQI, detailed route course is designed and depicted from two aspects, including router and terminal moving. There are two situations when router moves, one is router moving close to front-hop node, the other is router moving close to next-hop node. In link switching based on critical energy, there are alse two situations, including one front-hop node could find new link and two-front-hop node could find new link. In the end , data frames used in the two strategys and process of dealing with data received are presented.