We present a novel cross layer approach to random access (RA) that combinesphysical-layer network coding (PLNC) with multiuser detection (MUD). PLNC andMUD are applied jointly at the physical level in order to extract any linearcombination of messages experiencing a collision. The set of combinationsextracted from a whole frame is then processed by the receiver to recover theoriginal packets. A simple pre-coding stage at the transmitting terminalsallows the receiver to further increase system diversity. We derive ananalytical bound on the system throughput and present simulation results forthe decoding at the physical level as well as several performance measures atframe level in block fading channels, namely throughput, packet loss rate andenergy efficiency. The results we present are promising and suggest that across layer approach leveraging on the joint use of PLNC and MUD cansignificantly improve the performance of RA systems.
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