Beyond 1$\to$N Decoding: Capacity-Aware Rateless Polar Codes for IR-HARQ

2026-05-29

AI Summary

This work proposes a novel rateless polar coding framework tailored for incremental redundancy hybrid automatic repeat request (IR-HARQ) systems, addressing the limitations of conventional polar codes that struggle to support arbitrary transmission lengths and employ fixed decoding orders ill-suited for dynamic channel conditions. By integrating capacity-aware sub-block scheduling, a generalized decoding order, nested parity-check polar construction, and inverse bit mapping, the proposed scheme enables continuous and efficient transmission over any length interval. It is the first to jointly incorporate capacity-aware scheduling with flexible decoding ordering, achieving performance across the entire rate range that closely approaches that of individually optimized fixed-rate schemes. The design has been validated through hardware implementation, demonstrating its suitability for next-generation wireless data channels.

Abstract

This paper introduces a novel framework for polar codes, designed for flexible Incremental Redundancy Hybrid Automatic Repeat Request (IR-HARQ). By generalizing the decoding order beyond the standard 1$\to$N sequence, we enable a capacity-aware scheduling strategy that prioritizes the decoding of reliable subblocks. The framework integrates nested parity-check polar construction and reverse bit-mapping to support continuous and arbitrary transmission lengths $E \in [N_{\min}, N_{\max}]$. Simulation results show that the proposed rateless codes match the coding gain of independently optimized fixed-rate codes across the entire range of rates and lengths. With a validated hardware implementation, this work provides a practical solution for next-generation wireless data channels.

Problem

• Rateless Polar Codes
• IR-HARQ
• Flexible Transmission Length
• Capacity-Aware Scheduling
• Incremental Redundancy

Innovation

• Rateless Polar Codes
• IR-HARQ
• Capacity-Aware Scheduling
• Nested Parity-Check
• Flexible Decoding Order