Research Of Localization Method Of Wireless Sensor Network Based On Antenna Diversity Technology

Localization technology is one of the key technologies of wireless sensor network(WSN). Getting the location information of nodes is a basic function of WSN. The information gained by sensor nodes doesn’t make any sense if unable to get the location of sensor nodes. Improving the positioning accuracy has been a direction that WSN positioning technology researchers ever made efforts. Positioning technology hasn’t got a big breakthrough because of the influence of multipath fading. Therefore, it is significant to design new low cost localization nodes and research low complexity localization algorithm.As to the problem that ranging is easily affected by multipath fading in localization algorithm based on received signal strength indicator(RSSI) in WSN, a method of applying antenna diversity technology to WSN was put forward. Antenna diversity technology was applied to the anchor nodes successfully in this paper, the anchor nodes can work in both single antenna pattern and dual antenna pattern. In the experimental test, the mean error of positioning system was 4.35 meters when antenna diversity technique not used while 3.16 meters when used. The positioning error was decreased by 27.4%. Compared with normal node, antenna diversity node only needs to add an antenna and a few capacitances an inductance. It will not cost too much and has great value of engineering application.This paper also presents a localization algorithm of correcting the RSSI value. Influenced by the field environment of deployment of nodes and their own hardware performance, the deviation of RSSI measured and the experience value are often not the same, so RSSI influence factor of nodes was put forward. By broadcasting and receiving between anchor nodes, each anchor node’s RSSI influence factor can be got by calculation. RSSI values after correction can be got when RSSI value minus the RSSI influence factor of corresponding anchor nodes. Then the coordinates of the unknown node can be calculated with the trilateral localization algorithm. Through simulation and actual test, it’s proved that it had higher positioning accuracy using RSSI after correction than using RSSI not corrected in calculation of unknown node’s coordinate. In the algorithm, each anchor node only needs to send broadcast information once after anchor nodes deployed for calculating RSSI influence factor of anchor nodes, no extra communication needed, so the early communication costs were negligible. The algorithm was completely suitable for the situation of low power consumption and small amount of calculation.