Coding for the unsourced B-channel with erasures: enhancing the linked loop code

TL;DR

This paper extends the linked loop code to the unsourced B-channel with erasures, demonstrating improved performance over the tree code through enhancements and numerical simulations.

Contribution

The paper introduces an extension of the linked loop code for the UBCE, a new channel model, and shows its superiority over existing tree codes.

Findings

Enhanced linked loop code outperforms tree code on UBCE.

Numerical simulations confirm the effectiveness of the proposed code.

The UBCE model captures multiplicity of symbols in unsourced random access.

Abstract

In [1], the linked loop code (LLC) is presented as a promising code for the unsourced A-channel with erasures (UACE). The UACE is an unsourced multiple access channel in which active users' transmitted symbols are erased with a given probability and the channel output is obtained as the union of the non-erased symbols. In this paper, we extend the UACE channel model to the unsourced B-channel with erasures (UBCE). The UBCE differs from the UACE in that the channel output is the multiset union, or bag union, of the non-erased input symbols. In other words, the UBCE preserves the symbol multiplicity of the channel output while the UACE does not. Both the UACE and UBCE find applications in modeling aspects of unsourced random access. The LLC from [1] is enhanced and shown to outperform the tree code over the UBCE. Findings are supported by numerical simulations.