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Main Authors: Cheng, Xuejun, Zhang, Qian, Xu, Yunnuo, Dong, Zheng, Liu, Ju, Clerckx, Bruno
Format: Preprint
Published: 2026
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Online Access:https://arxiv.org/abs/2602.18077
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author Cheng, Xuejun
Zhang, Qian
Xu, Yunnuo
Dong, Zheng
Liu, Ju
Clerckx, Bruno
author_facet Cheng, Xuejun
Zhang, Qian
Xu, Yunnuo
Dong, Zheng
Liu, Ju
Clerckx, Bruno
contents This document serves as supplementary material for our journal submission, providing detailed mathematical proofs and derivations that support the results presented in the main manuscript. Specifically, under a modeling framework that jointly considers transceiver hardware impairments and imperfect successive interference cancellation (SIC), we systematically derive and prove from an optimality perspective that: when the residual interference coefficient approaches 1 (i.e., SIC becomes severely ineffective), there exists an optimal solution such that the common stream beamformer satisfies $\bm w_c^\star=\bm 0$, and hence the optimal rate-splitting multiple access (RSMA) transmission structure degenerates into space division multiple access (SDMA). This conclusion provides a verifiable theoretical justification for the convergence phenomenon observed in simulations, namely that "the RSMA performance gradually approaches that of SDMA as SIC degrades", and can also serve as a reference for multiple-access selection and system design in SIC-limited scenarios.
format Preprint
id arxiv_https___arxiv_org_abs_2602_18077
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Optimality Analysis of RSMA Degenerating to SDMA Under Imperfect SIC
Cheng, Xuejun
Zhang, Qian
Xu, Yunnuo
Dong, Zheng
Liu, Ju
Clerckx, Bruno
Information Theory
This document serves as supplementary material for our journal submission, providing detailed mathematical proofs and derivations that support the results presented in the main manuscript. Specifically, under a modeling framework that jointly considers transceiver hardware impairments and imperfect successive interference cancellation (SIC), we systematically derive and prove from an optimality perspective that: when the residual interference coefficient approaches 1 (i.e., SIC becomes severely ineffective), there exists an optimal solution such that the common stream beamformer satisfies $\bm w_c^\star=\bm 0$, and hence the optimal rate-splitting multiple access (RSMA) transmission structure degenerates into space division multiple access (SDMA). This conclusion provides a verifiable theoretical justification for the convergence phenomenon observed in simulations, namely that "the RSMA performance gradually approaches that of SDMA as SIC degrades", and can also serve as a reference for multiple-access selection and system design in SIC-limited scenarios.
title Optimality Analysis of RSMA Degenerating to SDMA Under Imperfect SIC
topic Information Theory
url https://arxiv.org/abs/2602.18077