Packet switched technology has been demonstrated effective in cellular radio systems with short propagation delay, not only for data but also for voice transmission. In fact, packet voice can efficiently exploit speech on-off activity to improve bandwidth utilization over TDMA. Such an approach has been first suggested in the Packet Reservation Multiple Access (PRMA) technique, an adaptation of the Reservation ALOHA protocol to the cellular environment. However, being PRMA based on a fixed...