Dilution of Position Calculation for MS Location Estimation in Wireless Communication Systems
摘要：
Geometric dilution of precision (GDOP) represents the geometric effect on the relationship between measurement error and positioning determination error. When the measurement variances are equal in each other, GDOP could be the most appropriate selection criterion of location measurement units. GDOP expression has simpler form if all the measurements with the same variance. For time of arrival (TOA) schemes,the maximum volume method of GDOP calculation does not guarantee the optimal selection of the four measurement units. The conventional method for calculating GDOP is to use matrix inversion to all subsets.GDOP was originally used as a criterion for selecting the right 3D geometric configuration of satellites in global positioning systems (GPS). In this paper, we employ GDOP using the matrix inversion method to select appropriate base stations (BSs) in cellular communication systems. The proposed BS selection criterion performs better than the random subsets of four or five BSs chosen from all seven BSs. After BS selection, the proposed distance-weighted method and threshold method for TOA schemes yields superior mobile station (MS)location estimation accuracy. For time of difference arrival (TDOA) schemes, the proposed BS selection criterion provides better MS location estimation. From simulation results, the performances of MS location strongly depend on the relative position of the MS and BSs.
