The Research On WSN Location Technology

Location based on WSN(Wireless Sensor Network) is a new technology, whichhas a very wide range of applications in environmental monitoring, defense andmilitary, warehouse management, disaster ahead, maintaining order, prevention andcontrol, and other fields. Currently the location method using wireless sensor networkcontains technologies based ranging and non-ranging. TOA, TDOA, AOA and RSSIare ranging technology-based location algorithms; the mainly non-rangingtechnology-based location algorithms are: Centroid algorithm, APIT algorithm,DV-HOP algorithm and so on. CC2431location engine is based on RSSI (ReceivedSignal Strength Indicator) technology, after getting the distance between nodes usingRSSI ranging, we can use trilateral measurement to calculate the location of blindnode. Due to the presence of ranging error, and the RSSI is easily affected by theenvironment, and generate attenuation and resulting in a low accuracy. So there aremany problems to be solved to create a stable location system.In order to solve the above problems, a complete wireless sensor networklocation system needs to be built in the paper, which can complete data collection,transmission and display of the entire location system. In this paper, we study on theoverall framework of WSN location, build a hardware platform, analyze and select thenetwork topology. The collected data is uploaded to the PC, and the PC displays thelocation results.the characteristics of CC2431location results are mainly analyzed in this paper,such as instability and being easily affected by the environment. Firstly, theparameters of wireless transmission model are analyzed, and the main parameters arechosen to optimize. Then we focuse on the factors of RSSI susceptible to environmentlike: the node transmission distance, transmission power, electromagnetic interference(Bluetooth interference, phone calls interference, WLAN interference, microwaveinterference), obstruction, power supply, antenna height, antenna angle, changes ofatmospheric, humidity, hardware characteristics (length of the antenna, characteristicsof the material), etc. After analysis of the location error generated by these factors,make some feasible solutions.Aiming to the low location accuracy and big error of CC2431, a location methodin which the location engine of CC2431combined with the improvedweighted-centroid algorithm is focused on in this paper. The impact of the decisionsize of reference node to blind node coordinate is reflected by introducing a weightedfactor in CC2431location engine. By doing this, we improve the accuracy of location,and implement the algorithm by hardware. To verify the performance of the algorithm,CC2431location engine and improved algorithm are compared in the ideal case. The result verifies that the superiority of the improved algorithm. And for differentenvironmental interference within the IOT lab, we propose to use the traditionalmethod of least squares to correct RSSI parameter. Experiments show that after theparameters correction, the location error is in a predetermined error range, the locationaccuracy is improved, and at last a better location effect is achieved.