Research on Low-Power Transmission Method for Group-Connected Beyond-Diagonal Reconfigurable Intelligent Surface-assisted Communication Systems

WANG Hong; LI Peiqi; LI Heyi; WANG Peiyu

doi:10.11999/JEIT241029

Volume 47 Issue 7

Jul. 2025

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Article Navigation > Journal of Electronics & Information Technology > 2025 > 47(7): 2073-2079

WANG Hong, LI Peiqi, LI Heyi, WANG Peiyu. Research on Low-Power Transmission Method for Group-Connected Beyond-Diagonal Reconfigurable Intelligent Surface-assisted Communication Systems[J]. Journal of Electronics & Information Technology, 2025, 47(7): 2073-2079. doi: 10.11999/JEIT241029

Citation:

WANG Hong, LI Peiqi, LI Heyi, WANG Peiyu. Research on Low-Power Transmission Method for Group-Connected Beyond-Diagonal Reconfigurable Intelligent Surface-assisted Communication Systems[J]. Journal of Electronics & Information Technology, 2025, 47(7): 2073-2079. doi: 10.11999/JEIT241029

Citation:

WANG Hong, LI Peiqi, LI Heyi, WANG Peiyu. Research on Low-Power Transmission Method for Group-Connected Beyond-Diagonal Reconfigurable Intelligent Surface-assisted Communication Systems[J]. Journal of Electronics & Information Technology, 2025, 47(7): 2073-2079. doi: 10.11999/JEIT241029

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Research on Low-Power Transmission Method for Group-Connected Beyond-Diagonal Reconfigurable Intelligent Surface-assisted Communication Systems

doi: 10.11999/JEIT241029 cstr: 32379.14.JEIT241029

School of Communications and Information Engineering, Nanjing University of Posts and Telecommunications, Nanjing 210003, China

Funds: The National Natural Science Foundation of China (62171237), The Natural Science Foundation of Jiangsu Provincial (BK20231285), The Postgraduate Research & Practice Innovation Program of Jiangsu Province (SJCX24_0289)

Received Date: 2024-11-20
Rev Recd Date: 2025-03-19

Available Online: 2025-03-28

Publish Date: 2025-07-22

Abstract

Abstract

Objective Reconfigurable Intelligent Surface (RIS) technology enables dynamic reconfiguration of the wireless communication environment. Among recent advancements, Beyond-Diagonal RIS (BD-RIS) has emerged as a novel architecture, featuring a phase-shift matrix unconstrained by diagonal form. This allows simultaneous adjustment of phase and amplitude, offering greater design flexibility and improved system performance. However, while prior studies have primarily focused on BD-RIS-assisted downlink systems, the uplink counterpart remains unexplored. Unlike downlink transmission, where only the total base station power is constrained, uplink transmission imposes individual power limitations on each user, necessitating different optimization models. Therefore, existing downlink-oriented design approaches cannot be directly applied to uplink scenarios. This study proposes a low-power transmission method tailored for BD-RIS-assisted uplink systems, addressing the unique constraints and challenges of uplink-communication. Methods This study investigates a group-connected BD-RIS-assisted uplink communication system to minimize total transmit power by jointly optimizing the equalizer, user transmit power, and BD-RIS phase-shift matrix. The Minimum Mean-Square Error (MMSE) equalizer is employed to maximize the Signal-to-Interference-plus-Noise Ratio (SINR) of each received signal. Subsequently, an analytical expression linking user transmit power and the phase-shift matrix is derived. The phase-shift optimization problem is then reformulated as an unconstrained univariate optimization problem. Finally, an alternating optimization approach is applied to iteratively refine the equalizer, user transmit power, and BD-RIS phase-shift matrix, achieving minimal system transmit power. Results and Discussions The proposed scheme is compared with benchmark methods, and simulation results demonstrate its superior convergence (Fig. 2) and performance (Figs. 3 and 4). The group-connected BD-RIS achieves lower total transmit power than the traditional single-connected RIS (Figs. 3 and 4) due to its ability to manipulate both the phase and amplitude of signals, leading to enhanced system performance. Furthermore, larger group sizes in the group-connected BD-RIS result in improved performance (Figs. 3 and 4), as increased group size provides greater design flexibility, further optimizing system efficiency. Conclusions To address the limitations of existing BD-RIS research, this study investigates a group-connected BD-RIS-assisted uplink communication system and proposes a method to minimize total transmit power. An optimization problem is formulated to minimize user transmit power, and an alternating optimization approach is employed to iteratively refine the equalizer, user transmit power, and BD-RIS phase-shift matrix. Specifically, the MMSE equalizer maximizes each user’s SINR, a closed-form expression for user power is derived, and the phase-shift optimization problem is transformed into an unconstrained single-variable optimization problem, achieving minimal system power consumption. Simulation results indicate that, compared with the traditional single-connected RIS, the group-connected BD-RIS achieves lower system transmit power, with performance improving as group size increases. This study assumes perfect channel state information; however, in practical RIS-assisted communication systems, accurately obtaining ideal channel state information is challenging. Future research should consider the effects of non-ideal channel state information.
- Beyond-Diagonal Reconfigurable Intelligent Surface (BD-RIS),
- Power minimization,
- Uplink communication,
- Alternating optimization

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References(17)

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