| 摘要 |
<p>In a satellite communications system where a plurality of spot beams (30) are provided on the earth (14) as effective cells (301) for a telephone system, and where every spot beam has a broadcast channel which is used to maintain the camping of user terminals (38) on their cell (301), a substitute broadcast channel f8 is provided in any spot beam (30) where it may become necessary to switch of the main broadcast channel f1, the main f1 and the substitute f8 broadcast channels being provided simultaneously for a predetermined time before the main broadcast channel f1 is switched off. The substitute broadcast channel f8 is provided at a higher power than the main broadcast channel f1 to ensure acquisition thereof by user terminals (38) seeking a new broadcast channel.</p> |
