Geographic Information System (GIS) based positioning technique is defined as a positioning technique using geographic information in order to improve the positioning accuracy. When vehicles equipped with Global Positioning System (GPS) receiver are driving in urban environments, the receiver would have considerable positioning error due to multipath and non-line-of-sight (NLOS) reception. Proposed Virtual Satellite Constrained – Weighted Least Square (VSC-WLS) technique could correct errors in this environment especially. In this paper, first we build a 3D building model made with GIS data, and use it to determine whether the received signals are LOS or NLOS. Then we place a virtual satellite (VS) obtained through the stochastic calculation using Signal to Noise Ratio (SNR) measurement model. Finally we could obtain satisfactory positioning results using WLS (Weighted Least Square) estimation with the VS.

Keywords: geographic information system, virtual satellite, weighted least square