A novel public mobile radio (PMR) protocol

Traditional public mobile radio (PMR) systems are designed to maximize the efficiency of a few "critical" features. In particular: (i) group call, (ii) low bandwidth utilization per call, (iii) instant (push-to-talk, PTT) communications. The resulting protocols trade-off a number of features that are taken for granted in other wireless communications products, like full duplex conversations and extended battery life (i.e. /spl Gt/8 hrs). In this paper we propose a digital PMR protocol that incorporates all the traditional PMR features, but also integrates some useful features. The protocol incorporates a "pseudo-duplex" feature that mimics full-duplex operation while maintaining narrow bandwidth utilization, and achieves extended battery life through sleep modes and power control.