Improving Performamce 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 e cient 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 onedimensional modulation schemes. Results show that the proposed coded PRMA yields signi cant 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.