Wireless location with NLOS error mitigation in Korean CDMA system

In this paper some wireless location experiments using CDMA pilot channels are carried out and an estimation technique to improve its positioning accuracy is proposed. Together with the GPS (global positioning system), lots of positioning technologies using existing infrastructure, that is, mobile communication networks, are being researched. Because of the shortage of hearable signals, multipath, and NLOS (non-line-of-sight) error, however, CDMA positioning has low positioning accuracy by raw pilot measurements only. In this paper, we introduce an adequate two-stage filter to treat such path-loss errors and develop a path-loss error mitigation algorithm. We apply these to the real positioning system and carry out experiments in the dense urban area. Friedland (1969) proposed the optimal filter to reject unknown bias that is difficult to be estimated. This paper shows a design rule that the filter can be applied to CDMA location and make the positioning accuracy better.