Rateless Codes for the Multi-Way Relay Channel

TL;DR

This paper introduces buffer-enhanced distributed Luby transform codes for multi-way relay networks, optimizing degree distribution via density evolution and linear programming to improve efficiency and robustness over erasure channels.

Contribution

It proposes a novel buffer-based DLT coding scheme with optimized degree distribution for multi-way relay channels, improving overhead and erasure performance.

Findings

Significant reduction in overhead and erasure rates.

Buffer at the relay improves performance under uplink erasures.

Finite-length code results match asymptotic analysis.

Abstract

We consider distributed Luby transform (DLT) codes for efficient packet transmission in a multi-way relay network, where the links are modeled as erasure channels. Density evolution is applied for asymptotic performance analysis, and subsequently used in a linear-programming design framework for optimizing the degree distribution at the relay in terms of overhead. Moreover a buffer is introduced at the relay to enable efficient downlink transmission even if packets are lost during uplink transmission. Performance losses in terms of delay and/or erasure rates caused by link erasures during uplink transmission are thus alleviated. The proposed DLT codes provide significant improvements in overhead and decoded erasure rates. Numerical results for finite-length codes follow closely the asymptotic analysis. Our results demonstrate that the proposed buffer-based DLT codes outperform its counterparts for lossy uplink transmission.