Enhanced Link Adaptation for Extended Reality Code Block Group based HARQ Transmission

TL;DR

This paper introduces two low-complexity enhanced link adaptation algorithms for XR traffic in 5G, significantly increasing system capacity by optimizing HARQ feedback and reducing retransmission resource use.

Contribution

The paper proposes novel eOLLA algorithms that leverage CBG-based HARQ multi-bit feedback to improve downlink capacity for XR in 5G networks.

Findings

System capacity increased by up to 67% with eOLLA algorithms.

Algorithms effectively reduce radio resource utilization during retransmissions.

Evaluation confirms the algorithms' superiority over traditional OLLA methods.

Abstract

Extended Reality (XR) is one of the most important media applications in 5\textsuperscript{th} Generation (5G) and 5G-Advanced. XR traffic is characterized by high data rates with bounded latency constraints, which is challenging for bandwidth-constrained wireless systems. In this paper, we propose two new low-complexity enhanced Outer Loop Link Adaptation (eOLLA) algorithms that significantly improve the downlink system capacity in terms of satisfied XR users. The algorithms exploit the Code Block Group (CBG)-based Hybrid Automatic Repeat reQuest (HARQ) multi-bit feedback for minimizing the radio resource utilization in retransmissions by controlling the first and second block error operation points. Evaluation by means of both analytical assessment and realistic system-level simulations verifies that the proposed eOLLA algorithms increase system capacity by up to \SI{67}{\percent} compared to known OLLA algorithms with traditional transport block based HARQ.