ARUM: Polar Coded HARQ Scheme based on Incremental Channel Polarization

TL;DR

ARUM is a flexible polar coded HARQ scheme that adaptively relocates bits based on reliability, improving coding gain through incremental channel polarization and inter-transmission channel transformation.

Contribution

The paper introduces ARUM, a novel HARQ scheme that enhances polar coding by bit relocation and channel transformation, enabling flexible transmissions with near-optimal performance.

Findings

Achieves near-optimal coding gain in simulations.

Allows different code lengths and rate-matching per transmission.

Utilizes incremental channel polarization for reliability updates.

Abstract

A hybrid ARQ (HARQ) scheme for polar code, which is called active-bit relocation under masks (ARUM), is proposed. In each transmission, the data bits are encoded and bit-wisely XOR-masked using a binary vector before being transmitted through the channel. The masking process combines multiple transmissions together which forms another step of inter-transmission channel transform. The reliabilities are updated after every transmission, and the less reliable bits in earlier ones are relocated to the more reliable positions at the latest transmitted block. ARUM is a very flexible HARQ scheme which allows each transmission to have a different mother code length and to adopt independent rate-matching scheme with sufficient channel state feedback in HARQ process. Simulation shows that ARUM can obtain near-optimal coding gain.