Relay-Assisted Carrier Aggregation (RACA) Uplink System for Enhancing Data Rate of Extended Reality (XR)

TL;DR

This paper proposes a relay-assisted carrier aggregation system for XR uplink transmission, using algorithms to optimize data rates, resulting in a 32% improvement over conventional schemes.

Contribution

It introduces a novel relay-assisted carrier aggregation system with centralized and distributed algorithms for uplink data rate maximization in XR applications.

Findings

Achieves 32% higher data rate compared to conventional schemes.

Develops iterative WMMSE-based optimization for centralized protocol.

Designs SVD-based water-filling algorithms for distributed protocol.

Abstract

In Extended Reality (XR) applications, high data rates and low latency are crucial for immersive experiences. Uplink transmission in XR is challenging due to the limited antennas and power of lightweight XR devices. To improve data transmission rates, we investigate a relay-assisted carrier aggregation (RACA) system. The XR device simultaneously transmits data to an access point (AP) and a relay in proximity over low-frequency and high-frequency bands, respectively. Then, the relay down-converts and amplifies the signals to the AP, effectively acting as an additional transmit antenna for the XR device. In this paper, we propose two algorithms to maximize the data rate of the XR device in their respective protocols. In the centralized protocol, the rate maximization problem is equivalently transformed as a weighted mean square error minimization (WMMSE) problem which can be solved iteratively by alternative optimization. In the distributed protocol, the rate maximization problem is decomposed into two independent sub-problems where the rate of the direct link and the rate of the relay link are maximized by singular value decomposition (SVD)-based methods with water-filling (WF). Simulation results show that the rate of the RACA system is improved by $32\%$ compared to that of the conventional carrier aggregation scheme.