Improving performance of wireless networks using collision resistent modulations

Recent work by the authors presents a novel class of signal space codes called Collision Resistant Modulations (CRM) for bandwidth efficient transmission on a random access collision channel, as in packet-radio applications. Results show that CRMs achieve a signi_cant gain over traditional modulation formats under a Slotted ALOHA protocol. In this paper, we investigate the potentials of using CRM under a partially ordered access protocol like Packet Reservation Multiple Access (PRMA). A system based on Reed-Solomon coded CRM is compared with a more traditional system using the same Reed-Solomon coding concatenated with simple one-dimensional modulation schemes. Results show that the proposed coded PRMA yields significant improvements in terms of both blocking probability and number of established calls (served users), at the expenses of a slight increase in the average transmitted power.