| 摘要 |
<p>In a cellular radio system the facility is provided for a call to be broadcast from a control centre (Mx), (for example an emergency service controller), or from any of the mobile units (Ma), (Mb), (Mc) etc., to all of the others. Each cell allocates a single channel to the broadcast service, irrespective of the number of mobile units in the cell. This allows more efficient use of the available channels than the use of a separate channel for each mobile unit. In one embodiment no channel is allocated to a cell unless at least one mobile unit responds to a paging signal in that cell. Paging may continue throughout a broadcast call to allow a channel to be allocated when a mobile unit enters a previously unoccupied cell or to allow release of a channel should all mobiles leave a previously occupied cell. The broadcast facility can be provided on a cellular network which also supports other mobile units which do not receive the broadcast service, and whose operation is not affected by it.</p> |
