| 摘要 |
<p>An apparatus and method for paging a user terminal (UT) using a satellite communications system having a gateway (120, 122) and one or more satellites (116, 118), wherein each satellite produces a plurality of beams (401-416) and each beam includes a plurality of channels. The method of the present invention includes the step of recalling a location of the UT (124, 126), wherein the recalled location corresponds to a location of the UT at a time t1 (904). The method also includes the step of determining an area, based on the recalled location, within which the UT (124, 126) is assumed to be located at a time t2 (906), where time t2 is later in time than time t1. The next step is to determine a time t3, where t3 is equal to or later in time than time t2, when the following two criteria are satisfied (908). First a satellite of the one or more satellites has an elevation angle between υ1 and 02. Second, all locations within the area are located within a footprint (400) of the satellite (that has an elevation angle between υ1 and υ2). The elevation angles υ1 and υ2 can be determined from the perspective of the recalled location. Alternatively, the elevation angle can be determined from the perspective of all locations within the area. This ensures that the UT (124) is in the 'sweet spot' (518, 522) of the satellite (116) (where the gain of signals sent from the satellite are highest) when the UT (124) is paged. By waiting until the UT is within the 'sweet spot' to page the UT, less power can be used by the satellite (116).</p> |
