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arXiv · 2203.07042

Hybrid Active-Passive Reconfigurable Intelligent Surface-Assisted Multi-User MISO Systems

Nhan Thanh Nguyen·Van-Dinh Nguyen·Qingqing Wu·Antti Tolli·Symeon Chatzinotas·Markku Juntti
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Abstract

We consider a multi-user multiple-input single-output (MISO) communications system which is assisted by a hybrid active-passive reconfigurable intelligent surface (RIS). Unlike conventional passive RISs, hybrid RIS is equipped with a few active elements with the ability to reflect and amplify incident signals to significantly improve the system performance. Towards a fairness-oriented design, we maximize the minimum rate among all users through jointly optimizing the transmit beamforming vectors and RIS reflecting/amplifying coefficients. Combining tools from block coordinate ascent and successive convex approximation, the challenging nonconvex problem is efficiently solved by a low-complexity iterative algorithm. The numerical results show that a hybrid RIS with 4 active elements out of a total of 50 elements with a power budget of -1 dBm offers an improvement of up to 80% to the considered system, while that achieved by a fully passive RIS is only 27%.

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Nhan Thanh Nguyen, Van-Dinh Nguyen, Qingqing Wu, Antti Tolli, Symeon Chatzinotas, Markku Juntti. 2022-03-14. Hybrid Active-Passive Reconfigurable Intelligent Surface-Assisted Multi-User MISO Systems. https://arxiv.org/abs/2203.07042

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