Beamforming Design for STAR-RIS-Assisted NOMA with Binary and Coupled Phase-Shifts

Area of Science:

• Wireless communication systems
• Intelligent reflecting surfaces
• Signal processing

Background:

• Non-orthogonal multiple access (NOMA) systems face challenges in maximizing throughput and performance.
• Simultaneously Transmitting and Reflecting Reconfigurable Intelligent Surfaces (STAR-RIS) offer a promising solution for enhancing wireless communication environments.
• Joint optimization of active and passive beamforming is crucial for unlocking the full potential of STAR-RIS in NOMA systems.

Purpose of the Study:

• To investigate the joint optimization of active and passive beamforming in STAR-RIS-assisted NOMA systems.
• To maximize system throughput and improve overall performance.
• To develop an efficient algorithmic framework for this optimization problem.

Main Methods:

• An iterative algorithmic framework is proposed for joint optimization.
• Fractional programming (FP) is used to reformulate the non-convex active beamforming problem into a convex one.
• Nesterov's extrapolation technique is employed to accelerate convergence and reduce computational load.
• A binary phase design method is utilized for STAR-RIS phase optimization, treating it as a unit circle segmentation problem for a closed-form solution.

Main Results:

• The proposed algorithmic framework demonstrates superior performance compared to existing benchmark algorithms.
• Significant improvements in system throughput are achieved.
• Enhanced computational efficiency is observed, reducing processing time.
• The method proves effective and practical for STAR-RIS-assisted NOMA systems.

Conclusions:

• The joint optimization of active and passive beamforming using the proposed framework is highly effective for STAR-RIS-assisted NOMA systems.
• The developed algorithms provide a practical and efficient solution for enhancing wireless communication performance.
• This research contributes to the advancement of intelligent reflecting surface technology in future wireless networks.