A Low-Complexity Design for Rate-Splitting Multiple Access in Overloaded MIMO Networks

TL;DR

This paper proposes a low-complexity rate-splitting multiple access scheme for overloaded MIMO networks, providing optimal power and rate allocation solutions that outperform traditional SDMA methods.

Contribution

It introduces a novel low-complexity RSMA design with closed-form solutions for resource allocation in overloaded MIMO networks, enhancing performance.

Findings

Proposed RSMA design outperforms SDMA in overloaded scenarios.

Closed-form solutions enable efficient resource allocation.

Significant performance gains demonstrated in simulations.

Abstract

Rate-Splitting Multiple Access (RSMA) is a robust multiple access scheme for multi-antenna wireless networks. In this work, we study the performance of RSMA in downlink overloaded networks, where the number of transmit antennas is smaller than the number of users. We provide analysis and closed-form solutions for optimal power and rate allocations that maximize max-min fairness when low-complexity precoding schemes are employed. The derived closed-form solutions are used to propose a low-complexity RSMA system design for precoder selection and resource allocation for arbitrary number of users and antennas under perfect Channel State Information at the Transmitter (CSIT). We compare the performance of the proposed design with benchmark designs based on Space Division Multiple Access (SDMA) to show that the proposed low-complexity RSMA design achieves a significantly higher performance gain in overloaded networks.