Low-Complexity RSMA Approach for Enhanced Multi-User Decode-and-Forward Relay Systems

Rate-Splitting Multiple Access (RSMA) has emerged as a robust transmission strategy for multi-antenna wireless systems. This paper investigates the performance of RSMA in a downlink Decode-and-Forward (DF) relay network under imperfect Channel State Information (CSI) at both the transmitter and the...

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Main Authors: Ahmet Sacid Sumer, Mehmet Mert Sahin, Huseyin Arslan
Format: Article
Language:English
Published: IEEE 2025-01-01
Series:IEEE Open Journal of the Communications Society
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Online Access:https://ieeexplore.ieee.org/document/10965750/
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author Ahmet Sacid Sumer
Mehmet Mert Sahin
Huseyin Arslan
author_facet Ahmet Sacid Sumer
Mehmet Mert Sahin
Huseyin Arslan
author_sort Ahmet Sacid Sumer
collection DOAJ
description Rate-Splitting Multiple Access (RSMA) has emerged as a robust transmission strategy for multi-antenna wireless systems. This paper investigates the performance of RSMA in a downlink Decode-and-Forward (DF) relay network under imperfect Channel State Information (CSI) at both the transmitter and the relay. The system operates in two phases: in the first phase, the Base Station (BS) transmits signals to both BS Users (BUs) and the relay; in the second phase, the relay decodes and forwards the signals to Relay Users (RUs) located outside the BS coverage area. RSMA is employed for facilitating transmission from both the BS and the relay. To optimize the network performance, we derive a tractable lower bound for the ergodic sum-rate, which enables the power allocation coefficients of common and private streams in the RSMA structures to maximize the overall sum-rate in both phases. The simulation results demonstrate that the proposed power allocation algorithm, coupled with a low-complexity precoding design, significantly improves the sum-rate performance of DF relay RSMA networks compared to scenarios where RSMA is not utilized. Notably, RSMA outperforms Spatial Division Multiple Access (SDMA)-based benchmarks, achieving sum-rate gains of up to 81%. Furthermore, a three-user use-case scenario is examined, revealing that RSMA consistently surpasses Non-Orthogonal Multiple Access (NOMA) and Orthogonal Multiple Access (OMA)-based benchmarks, even in the presence of imperfect channel state information (CSI) at both the transmitter and the relay.
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spelling doaj-art-8a169323c140408e9514ecc011697db82025-08-20T02:14:42ZengIEEEIEEE Open Journal of the Communications Society2644-125X2025-01-0163904391910.1109/OJCOMS.2025.356082610965750Low-Complexity RSMA Approach for Enhanced Multi-User Decode-and-Forward Relay SystemsAhmet Sacid Sumer0https://orcid.org/0000-0001-8866-8520Mehmet Mert Sahin1https://orcid.org/0000-0001-5401-2427Huseyin Arslan2https://orcid.org/0000-0001-9474-7372Department of Electrical and Electronics Engineering, Istanbul Medipol University, Istanbul, TürkiyeSamsung Research America, Samsung Electronics Company Ltd., Plano, TX, USADepartment of Electrical and Electronics Engineering, Istanbul Medipol University, Istanbul, TürkiyeRate-Splitting Multiple Access (RSMA) has emerged as a robust transmission strategy for multi-antenna wireless systems. This paper investigates the performance of RSMA in a downlink Decode-and-Forward (DF) relay network under imperfect Channel State Information (CSI) at both the transmitter and the relay. The system operates in two phases: in the first phase, the Base Station (BS) transmits signals to both BS Users (BUs) and the relay; in the second phase, the relay decodes and forwards the signals to Relay Users (RUs) located outside the BS coverage area. RSMA is employed for facilitating transmission from both the BS and the relay. To optimize the network performance, we derive a tractable lower bound for the ergodic sum-rate, which enables the power allocation coefficients of common and private streams in the RSMA structures to maximize the overall sum-rate in both phases. The simulation results demonstrate that the proposed power allocation algorithm, coupled with a low-complexity precoding design, significantly improves the sum-rate performance of DF relay RSMA networks compared to scenarios where RSMA is not utilized. Notably, RSMA outperforms Spatial Division Multiple Access (SDMA)-based benchmarks, achieving sum-rate gains of up to 81%. Furthermore, a three-user use-case scenario is examined, revealing that RSMA consistently surpasses Non-Orthogonal Multiple Access (NOMA) and Orthogonal Multiple Access (OMA)-based benchmarks, even in the presence of imperfect channel state information (CSI) at both the transmitter and the relay.https://ieeexplore.ieee.org/document/10965750/Decode-and-forward relaysergodic sum-ratelinear precodingMU-MIMOrate splitting multiple access (RSMA)
spellingShingle Ahmet Sacid Sumer
Mehmet Mert Sahin
Huseyin Arslan
Low-Complexity RSMA Approach for Enhanced Multi-User Decode-and-Forward Relay Systems
IEEE Open Journal of the Communications Society
Decode-and-forward relays
ergodic sum-rate
linear precoding
MU-MIMO
rate splitting multiple access (RSMA)
title Low-Complexity RSMA Approach for Enhanced Multi-User Decode-and-Forward Relay Systems
title_full Low-Complexity RSMA Approach for Enhanced Multi-User Decode-and-Forward Relay Systems
title_fullStr Low-Complexity RSMA Approach for Enhanced Multi-User Decode-and-Forward Relay Systems
title_full_unstemmed Low-Complexity RSMA Approach for Enhanced Multi-User Decode-and-Forward Relay Systems
title_short Low-Complexity RSMA Approach for Enhanced Multi-User Decode-and-Forward Relay Systems
title_sort low complexity rsma approach for enhanced multi user decode and forward relay systems
topic Decode-and-forward relays
ergodic sum-rate
linear precoding
MU-MIMO
rate splitting multiple access (RSMA)
url https://ieeexplore.ieee.org/document/10965750/
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