Low-Complexity Coding Techniques for Cloud Radio Access Networks

TL;DR

This paper introduces low-complexity coding schemes for uplink and downlink in cloud radio access networks, reducing complex code design to single-user channel coding by leveraging rate-splitting and equivalence techniques.

Contribution

It demonstrates that achieving any rate in the C-RAN rate-fronthaul region can be reduced to designing a small set of point-to-point codes, simplifying code construction.

Findings

Achieves any point in the rate-fronthaul region with at most 4(K+L)-2 codes.

Establishes an equivalence between joint and successive coding regions.

Derives properties of the rate-fronthaul region for uplink C-RANs.

Abstract

The problem of coding for the uplink and downlink of cloud radio access networks (C-RAN's) with $K$ users and $L$ relays is considered. It is shown that low-complexity coding schemes that achieve any point in the rate-fronthaul region of joint coding and compression can be constructed starting from at most $4(K+L)-2$ point-to-point codes designed for symmetric channels. This reduces the seemingly hard task of constructing good codes for C-RAN's to the much better understood task of finding good codes for single-user channels. To show this result, an equivalence between the achievable rate-fronthaul regions of joint coding and successive coding is established. Then, rate-splitting and quantization-splitting techniques are used to show that the task of achieving a rate-fronthaul point in the joint coding region can be simplified to that of achieving a corner point in a higher-dimensional C-RAN problem. As a by-product, some interesting properties of the rate-fronthaul region of joint decoding for uplink C-RAN's are also derived.