| 摘要 |
A method and apparatus for determining the position of a mobile terminal using either an internal positioning system, such as a GPS receiver, or an external positioning system such as an external cellular positioning system. A handoff procedure is used to decide which positioning system is used to calculate the position of the mobile terminal. In one embodiment, the internal positioning system is preferred and the mobile terminal switches to the external positioning system only when the internal system is unavailable, and switches back when the internal system is functioning properly. Alternatively, the external positioning system is preferred and when it is unavailable the mobile terminal switches to the internal positioning system, but switches back to the external system when it is available. In one embodiment, the mobile terminal includes the internal positioning system, a transceiver, and a mobile terminal position controller. The mobile terminal position controller selects between the external and internal positioning systems depending on availability or other factors such as operator preference. |
