The Study On Indoor Positioning Technology Based On Wireless Sensor Network

In recent years, the indoor positioning technology plays an important role in the person localization, warehousing logistics, location for coal mine, emergency rescue work in complex personnel and items positioning circumstances. The indoor positioning technology based on wireless sensor networks has particular advantages by virtue of sensor node with low cost, low power consumption and convenience to data transmission. The paper focuses on the research as follows, which how to improve the indoor positioning accuracy of nodes. Firstly, the paper analyzed the composition of wireless sensor networks indoor positioning system and node networking protocol combined in detail. Then discussed wireless sensor network based on location principle of ranging and range-free, and analyzed positioning performance of centroid and DV-Hop algorithm.Secondly, the characteristic of RSSI-d attenuation was researched, and the indoor signal path loss model was determined by analyzing the indoor signal model. The algorithm of weighted centroid localization based on RSSI distance measurement error correction was proposed to solve the problem of RSSI ranging error. The least square error of the distance measurement compensation method was adopted in the algorithm to modify the distance measurement based RSSI that can reduce the error of distance measurement. The weighted centroid localization algorithm was employed in positioning stage; moreover, weighted factor was determined by the different influence of beacon nodes to unknown nodes to improve the positioning accuracy. Simulation results show that the accuracy of this algorithm is better than the other weighted centroid localization algorithms in performance.Finally, the combination localization algorithm based on WLS and EKF was improved according to the large estimates deviation calculated by least squares algorithm between unknown node position and actual position. First, the weighted least squares algorithm was used to calculated node preliminary estimated position based on the RSSI ranging error correction algorithm, and the node preliminary estimated position as the EKF initial status. Then, EKF was used to iteratively calculate node location estimates. The stimulation results show that the algorithm has good positioning performance. Based on the algorithm, the optimal ordering scheme of selected beacon node involved in EKF iterative calculation was researched to further improve the node location accuracy.