M-DGPS: mobile devices supported differential global positioning system algorithm

Differential global positioning system (DGPS) is important for all kinds of navigation applications which can improve the positioning accuracy from around 15 m provided by standard point service (SPS) to about 1-2 m. It uses a network of continuous operating reference station (CORS) with known positions and broadcasts the correction between the measured satellite pseudoranges and actual (internally computed) pseudoranges, and receiver stations may correct their pseudoranges by the same amount. Hence, in order to implement DGPS, the raw pseudorange measurements of the receiver are required. It is not a problem for general GPS receivers, but for mobile devices with an integrated GPS chip, it is not feasible as the raw pseudorange measurements cannot be accessed for most mobile devices. In order to realize DGPS on mobile, a mobile DGPS (M-DGPS) algorithm is proposed which does not require the raw pseudorange measurements. As the mobile can provide a SPS solution and the satellite names which is used to get the solution, with the correction of these satellites received from the CORS network, a position correction can be calculated. Then, the solution can be improved after applying the position correction. The algorithm is tested in different areas of Fuzhou city, China, and the results show that the new M-DGPS algorithm can improve the positioning accuracy obviously and meet the accuracy requirements of some navigation and surveying applications most of the time in urban environments.