D.3 MS-Based GPS

03.713GPPFunctional descriptionLocation Services (LCS)Release 1999Stage 2TS

The MS-based solution maintains a fully-functional GPS receiver in the MS. This requires the same functionality as described in clause B.2, plus additional means for computing the positions of the satelites and ultimately the MS’s position. In the initial start-up scenario, significantly more data must be provided to the MS than for the MS-assisted case. However, this data is valid for four hours or more and can be updated as necessary over time. Typical transmissions include time, reference location, satellite ephemeris and clock corrections. If better position accuracy is required for certain applications, DGPS data must be transmitted to the MS frequently (approximately every 30 seconds). Since the DGPS data is valid for a large geographical area, one centrally located reference receiver can be used to service this large region. The final position of the MS is generated at the MS itself. The calculated MS location can then be sent to an application outside of the MS if required.