Trade-Off Performance Regions of Random Access Protocols with Multi-Packet Reception (MPR) via Multi-Objective Optimization

This paper revisits the study of random access protocols enabled with multi-packet reception capabilities (MPR) using multi-objective optimization tools. The work is focused on the characterization of the boundary (envelope) or the Pareto front curve of different types of trade-off performance region: the conventional throughput region, sum-throughput vs. fairness, and sum-throughput vs. power consumption. Fairness is evaluated by means of the Gini-index, which is a metric used in economics to measure income inequality. Transmit power is directly linked to the global transmission rate. For simplicity in the analysis, this paper focuses on a two-user Slotted ALOHA (S-ALOHA) system enabled with MPR. The results provide useful insights into the operation of MPR protocols under different reception scenarios. In weak MPR conditions, it is observed that the system has problems in achieving simultaneously good fairness and high sum-throughput, due to a non-convex throughput region. On the contrary, in scenarios with strong MPR, good fairness and high sum-throughput can be simultaneously achieved at the expense of high power consumption.