Intelligent reflecting surface (IRS) is envisioned to become a key technology for the upcoming six-generation (6G) wireless system due to its potential of reaping high performance in a power-efficient and cost-efficient way. With its disruptive capability and hardware constraint, the integration of IRS imposes some fundamental particularities on the coordination of multi-user signal transmission. Consequently, the conventional orthogonal and non-orthogonal multiple-access schemes are hard to directly apply because of the joint optimization of active beamforming at the base station and passive reflection at the IRS. Relying on an alternating optimization method, we develop novel schemes for efficient multiple access in IRS-aided multi-user multi-antenna systems in this paper. Achievable performance in terms of the sum spectral efficiency is theoretically analyzed. A comprehensive comparison of different schemes and configurations is conducted through Monte-Carlo simulations to clarify which scheme is favorable for this emerging 6G paradigm.

翻译：智能反射面（IRS）因其能够以高能效、低成本方式实现高性能的潜力，被视作即将到来的第六代（6G）无线系统的关键技术。凭借其颠覆性能力和硬件限制，IRS的集成对多用户信号传输的协调带来了一些基本特殊性。因此，由于需要在基站端的有源波束成形和IRS端的无源反射之间进行联合优化，传统的正交和非正交多址接入方案难以直接应用。本文基于交替优化方法，针对IRS辅助的多用户多天线系统，提出了高效多址接入的新方案。我们从理论上分析了以频谱效率总和为指标的可达性能，并通过蒙特卡洛仿真对不同方案与配置进行了全面比较，以明确哪种方案更适用于这一新兴的6G范式。