Irregular Repetition Slotted ALOHA Over the Binary Adder Channel

TL;DR

This paper introduces an IRSA-based random-access protocol for the binary adder channel, leveraging a new codebook construction and iterative decoding to improve user collision resolution and increase sum rate.

Contribution

It presents a novel codebook design and decoding method for IRSA over the BAC, surpassing previous schemes in resolving collisions and enhancing throughput.

Findings

Achieves higher sum rate than previous schemes

Resolves more colliding users per slot

Uses a new codebook construction for IRSA

Abstract

We propose an irregular repetition slotted ALOHA (IRSA) based random-access protocol for the binary adder channel (BAC). The BAC captures important physical-layer concepts, such as packet generation, per-slot decoding, and information rate, which are neglected in the commonly considered collision channel model. We divide a frame into slots and let users generate a packet, to be transmitted over a slot, from a given codebook. In a state-of-the-art scheme proposed by Paolini et al. (2022), the codebook is constructed as the parity-check matrix of a BCH code. Here, we construct the codebook from independent and identically distributed binary symbols to obtain a random-coding achievability bound. Our per-slot decoder progressively discards incompatible codewords from a list of candidate codewords, and can be improved by shrinking this list across iterations. In a regime of practical interests, our scheme can resolve more colliding users in a slot and thus achieves a higher average sum rate than the scheme in Paolini et al. (2022).