OFDM-RSMA: Robust Transmission under Inter-Carrier Interference

TL;DR

This paper introduces OFDM-RSMA, a novel scheme combining rate-splitting multiple access with OFDM to enhance interference management and improve sum-rate performance in wireless systems.

Contribution

It formulates a sum-rate maximization problem for OFDM-RSMA, proposing a WMMSE-based algorithm to optimize subcarrier and power allocation, demonstrating improved performance over traditional methods.

Findings

OFDM-RSMA outperforms OFDM-NOMA and OFDMA in various channel conditions.

The proposed scheme effectively mitigates ICI and other interference issues.

Numerical results confirm the robustness and flexibility of OFDM-RSMA.

Abstract

Rate-splitting multiple access (RSMA) is a multiple access scheme to mitigate the effects of the multi-user interference (MUI) in multi-antenna systems. In this study, we leverage the interference management capabilities of RSMA to tackle the issue of inter-carrier interference (ICI) in orthogonal frequency division multiplexing (OFDM) waveform. We formulate a sum-rate maximization problem to find the optimal subcarrier and power allocation for downlink transmission in a two-user system using RSMA and OFDM. A weighted minimum mean-square error (WMMSE)-based algorithm is proposed to obtain a solution for the formulated non-convex problem. We show that the marriage of rate-splitting (RS) with OFDM provides complementary strengths to cope with peculiar characteristic of wireless medium and its performance-limiting challenges including inter-symbol interference (ISI), MUI, ICI, and inter-numerology interference (INI). The sum-rate performance of the proposed OFDM-RSMA scheme is numerically compared with that of conventional orthogonal frequency division multiple access (OFDMA) and OFDM-non-orthogonal multiple access (NOMA). It is shown that the proposed OFDM-RSMA outperforms OFDM-NOMA and OFDMA in diverse propagation channel conditions owing to its flexible structure and robust interference management capabilities.