The GPS technology and the data computation processing have been improved to near real-time and precise positioning mode, like the Real-Time Kinametic (RTK) technique. But errors from the satellite system, atmosphere, receiver's clock et al., make the effective range of centimeter precision in several kilometers only between the base and rover stations. To expand the effective range and decrease the density of base stations, LSB will have set up a national e-GPS base stations network by 2006. In order to obtain high precision position results and provide a multi-goal positioning service with plus value application, the system will be involved in regional position error interpolating mode and Virtual Base Station (VBS) technique. The center is responsible for VBS maintenance and data management in northern Taiwan. In addition, the precise coordinates of the VBS and moving receiver in the field have to be computed by the center.