The Research Of Indoor Passive UHF RFID Localization Based On Convex Optimization

With the rapid development of mobile computing and embedded systems,people get more interesting on location-aware service.As the Internet of Thing play more and more important role in industrial production and family life,the researchers take more attention on indoor localization,especially passive UHF RFID tag localization.Unlike the outdoor environment,there always exists interference caused by furniture,equipment and people action in indoor environment,and these will cause reflections,scattering even diffraction and transmission phenomena in radio transmission.Indoor localization accuracy will become worse as the increase of environment complex due to the multiline and NLOS.So how to overcome this problem now is our first priority.In indoor wireless localization,traditional algorithms such as LS and Chan cannot satisfy the accuracy we demanded due to the NLOS.In this paper,under the condition of only noise error and NLOS error exist,we use convex optimization to eliminate the NLOS bias for location accuracy promoting.We use the Passive UHF RFID tag localization system,analyze and build a channel model,then give the composition of localization error.Meanwhile we introduce the concept of mathematics optimization,combine with the principle of convex optimization,we propose a two-step label location algorithm: first use Interior point algorithm to convert NLOS problem through Newton approach,then we use residual weighted algorithm to estimate the RFID tag position.Comparison of the simulation result will demonstrate that the performance of the proposed method is better than traditional methods.