Patent ID: 8289206

Claim:
A method for providing assistance data when determining a position of a mobile terminal being connected to a cellular communication system via a base station, comprising the steps of: providing satellite time reference data using a positioning node of the cellular communication system, said satellite time reference data comprising a relation between a frame time of said cellular communication system and a satellite reference time; using the positioning node, adapting a search window to a specific satellite from which a satellite ranging signal emerges based at least on said satellite time reference data; and, using the positioning node, providing said search window to said mobile terminal; wherein said step of providing satellite time reference data comprises the steps of: the positioning node receiving, from a multitude of mobile terminals over time, measured quantities representing said relation; the positioning node calculating an estimate of said relation from said received measured quantities representing said relation, as well as calculating an estimated inaccuracy of said estimate of said relation; wherein said step of adapting said search window is based on said estimated relation and said estimated inaccuracy of said estimated relation.