Prioritized Random MAC Optimization via Graph-based Analysis

TL;DR

This paper introduces a prioritized IRSA algorithm for heterogeneous sources in shared channels, optimizing transmission strategies to improve system utility, validated through theoretical analysis and experimental results.

Contribution

It develops a new prioritized IRSA scheme, derives collision resolution probabilities, and formulates an optimization for heterogeneous source transmission strategies.

Findings

Theoretical analysis accurately predicts collision resolution probabilities.

Optimized strategies significantly improve system utility.

Experimental results confirm the effectiveness of the proposed approach.

Abstract

Motivated by the analogy between successive interference cancellation and iterative belief-propagation on erasure channels, irregular repetition slotted ALOHA (IRSA) strategies have received a lot of attention in the design of medium access control protocols. The IRSA schemes have been mostly analyzed for theoretical scenarios for homogenous sources, where they are shown to substantially improve the system performance compared to classical slotted ALOHA protocols. In this work, we consider generic systems where sources in different importance classes compete for a common channel. We propose a new prioritized IRSA algorithm and derive the probability to correctly resolve collisions for data from each source class. We then make use of our theoretical analysis to formulate a new optimization problem for selecting the transmission strategies of heterogenous sources. We optimize both the replication probability per class and the source rate per class, in such a way that the overall system utility is maximized. We then propose a heuristic-based algorithm for the selection of the transmission strategy, which is built on intrinsic characteristics of the iterative decoding methods adopted for recovering from collisions. Experimental results validate the accuracy of the theoretical study and show the gain of well-chosen prioritized transmission strategies for transmission of data from heterogenous classes over shared wireless channels.