Design considerations of trunked radio systems

The design of the Motorola Trunked Radio System in use in the 800 MHz band in the United States is reviewed. The performance of the Message, Transmission, and Quasi-Transmission trunked channel assignment strategies is compared. Based on studies of trunked systems in operation in the US, Transmission and Ouasi-Transmission trunking are shown to be more efficient than Message trunking. The signaling channel of the Trunked System is used to receive service requests from mobile and portable units and transmit back channel assignments. If all voice channels are busy, requests are queued. Capacity requirements for the signalling channel used in Transmission Trunked-based systems are shown to be higher than those for Message Trunked Systems.