Trunked private mobile radio-a lead from the electricity industry

The author briefly reviews the development of private mobile radio and the problems it is now encountering due to limited frequency spectrum. To get the maximum use from a limited frequency spectrum, trunking has been adopted. Trunking increases the number of channels potentially available to a user, allowing a better trade-off between load and grade of service. The Joint Radio Committee is proposing the use of trunked PMR schemes for the electricity supply industry in England, Wales and possibly Scotland, and the gas industry for England, Wales and Scotland. Each industry will be allocated 36 channels. The plan for the electricity supply industry is described and the architecture of the system is briefly mentioned. The signalling protocol MPT 1327 will be used. The management of channel contention is also discussed