C-PRMA - A CENTRALIZED PACKET RESERVATION MULTIPLE-ACCESS FOR LOCAL WIRELESS COMMUNICATIONS

Packet-switched technology has been demonstrated as effective in cellu lar radio systems with short propagation delay, not only for data, but also for voice transmission, In fact, packet voice can efficiently ex ploit speech on-off activity to improve bandwidth utilization over tim e division multiple access (TDMA). Such an approach has been first sug gested in the packet reservation multiple-access (PRMA) technique, an adaptation of the reservation ALOHA protocol to the cellular environme nt, However, being PRMA-based oil a fixed frame scheme, it cannot thor oughly take advantage of the very short propagation delays encountered in microcellular systems that allow, for instance, the immediate retr ansmission of packets lost because of the interference noise from adja cent cells, In this paper, we present the centralized PRMA, a natural enhancement of PRMA, in which the base station (BS) plays a central ro le in scheduling the transmissions of mobile stations (MS's), As a con sequence, the transmission scheduling is very flexible and can account for the different traffic rate and delay constraints that emerge from voice and data integration packet retransmission policy to recover co rrupted packets can be implemented and operated efficiently to provide an acceptable grade of service, even in a very noisy environment. The simulation results presented in this paper show the quantitative impr ovements of the centralized packet reservation multiple-access (C-PRMA ) performance with respect to PRMA.