| 摘要 |
Reliable and efficient search windows are provided by allowing the adaptation of the code search window to be dependent on inaccuracy measures of relations between a cellular frame time and a satellite reference time. This inaccuracy is calculated in a positioning node of the cellular communications system, preferably by filtering of measurements received from user equipments. Linear trend Kalman filtering followed by post processing of estimation errors may be utilized. In order to ensure non-ambiguous interpretation of the received time stamps of received satellite signals provided by user equipments, a pseudo propagation delay is computed in both the user equipment and the positioning node based on GPS acquisition assistance data. The GPS time stamp is then defined referring to the determined pseudo propagation delay. In one embodiment, the pseudo propagation delay is assured to be situated within a pre-determined time interval.
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