Almanac maintenance for mobile station positioning

摘要

An almanac data management system at a location remote from a cell phone (20) has an almanac memory (44) for containing at least a current version of almanac data (52). A mobile device information memory (48) contains an identification of a version of almanac data held by the cell phone (20). A downloading system (56) selectively downloads at least a subset of the current version of almanac data (52) to the cell phone (20) if the current version of almanac data (52) is later than the version of almanac data held by the cell phone (20).

主权项

1. A mobile device, comprising:
means for storing almanac data; means for receiving information indicative of an up-to-date almanac version from a server; means for determining whether said almanac data stored by said mobile device is up-to-date; means for requesting up-to-date almanac data in response to a notification from a server, said notification from said server to be based, at least in part, on said server comparing changes to said almanac data with a known data subset of almanac data previously transmitted to said mobile device, said known data subset including almanac data for one or more selected base stations and excluding almanac data for at least one unselected base station of a wireless communication system in which said mobile device is currently roaming; and means for storing said up-to-date almanac data for said one or more selected base stations in a memory.