Study On Localization Algorithm Based On RFID

Radio Frequency Identification has been widely applied to positioning, especially the indoor positioning since it has numerous advantages, such as no contact and no sight line..This paper analyzes the current typical positioning algorithm. Among all the methods based on ranging technology, Received Signal Strength Indicator may delay the arrival time and the signal arrives quite late. Less accurate as the above methods, they are low-cost and easy to achieve. Among the methods not based on ranging technology, there exist enormous algorithm traffic and large energy consumption in DV-Hop and APIT. DV-Hop algorithm is low in positioning accuracy, while centroid algorithm has a small amount of calculation and energy consumption, whose positioning accuracy is totally based on connectivity and thus has comparatively large errors.Based on the advantages and disadvantages of current kinds of algorithm, this paper comes up with an improved algorithm------Centroid localization algorithm based on variable power. This method is to change the transmit power of positioning labels periodically, and to enter transmission power information and the ID of the localization tag for the first time which is received by the unknown tag within monitoring range. Thus we can know for sure the unknown tag lies in the annular area which is composed by the transmit power monitoring range of this localization tag's adjacent tags. Then we can select three of the smallest transmission power ones from the received location tag IDs and use grid scanning method to calculate the centroid of the overlapping area of the three annular regions which can be used as the position coordinates of the unknown tags.In order to verify the feasibility of the improved algorithm, this paper carries out in MATLAB the simulation of centroid localization algorithm, RSSI localization algorithm, APIT localization algorithm and Centroid localization algorithm based on variable power raised in this paper and then analyze and compare the positioning errors of various positioning algorithms. Simulation results show that the improved algorithm proposed in this paper has good positioning accuracy. This paper also studies the influence of positioning tag amounts, communication distance, wireless sensor network node layout on canalization accuracy, which provides referential value for practical use.