| 摘要 |
<p>A called subscriber unit's (26) geographic location (58) is provided by a gateway (22) and translated to location coordinates of a global coordinate system (50). The gateway (22) identifies an orbiting satellite communication station (12) servicing the subscriber unit's location, and sends the subscriber unit's ID and location data to the satellite. The subscriber unit's location data is translated to an angle (77) and range (78) relative to the satellite's nadir (74) using the satellite's ground track data. The angle and range are mapped to an antenna beam where the subscriber unit is located (73) using a look-up table onboard the satellite (12). An acquisition or ring-alert signal is transmitted within the antenna beam where the subscriber unit is located. When the range is outside the satellite's footprint (70), the subscriber unit's ID and location data are routed directly to another satellite currently servicing that location.</p> |
