Abstract: In a cellular mobile telecommunication system, a method and apparatus for controlling the process of locating a mobile unit from the cell sites. When a mobile unit goes beyond the radio range of its associated controlling cell site, that cell site sends a message to nearby cell sites to measure and report the strength of the received signal from that mobile on each of their directional antennas and to report radio channel availability. These reports are returned to the controlling cell site which compares the received signal strength mesurements against stored thresholds. The controlling cell site generates and transmits to the mobile telecommunications switching office (MTSO) a hand-off request message including a list of candidate hand-off cell sites and directional antennas. The MTSO then selects an available channel associated with one of the candidate cell sites and antennas and generates a sequence of messages to hand-off communications control from the controlling cell site to a candidate cell site.

Abstract: A high capacity, cellular, channel reuse, mobile, radiotelephone system supplies both nondispatch radiotelephone service and dispatch service with a fleet-calling capability. For the latter capability, unidirectional communication (48) is provided from a dispatcher station (39) to a fleet-listen radio channel (f.sub.FC10, f.sub.FC20) in each service region of the system where idle fleet mobile units are located. Bidirectional communication (46) is provided between one or more responding fleet units and a fleet dispatcher, and such communication is also applied to the fleet-listen channels.