Signalling and control protocol for a communication system.

摘要

A signalling and control protocol is provided wherein each subscriber unit (106) operating with a communication system (100) must transmit a request (200, 200 min or 200 sec ) to communicate to a central station. If a communication channel is available, the central station returns a channel grant (210), which includes a time code representing a time duration during which the requesting subscriber may communicate. After receiving the channel grant (210), the subscriber unit may communicate for a time interval not exceeding the time duration, and, immediately prior to the expiration of the time duration, the subscriber unit may itself provide a warning tone indicating the impending loss of the communication channel. Conversely, if a communication channel is not available, the central station provides a busy message (216), which includes a code (218) representing the requesting subscriber unit's position is a call request queue.