Intelligent reflecting surface (IRS) has recently emerged as a promising technology for 6 G wireless systems, due to its capability to reconfigure the wireless propagation environment. In this paper, we investigate a Rate-Splitting Multiple Access (RSMA) for IRS-assisted downlink system, where the base station (BS) communicates with single-antenna users with the help of an IRS. RSMA relies on rate-splitting (RS) at the BS and successive interference cancellation (SIC) at the users and provides a generalized multiple access framework. We derive a new architecture called IRS-RS that leverages the interplay between RS and IRS. For performance analysis, we utilize an on-off control technique to control the passive beamforming vector of the IRS-RS and derive the closed-form expressions for outage probability of cell-edge users and near users. Moreover, we also analyze the outage behavior of cell-edge users for a sufficiently large number of reflecting elements. Additionally, we also analyze the outage performance of cooperative RS based decode-and-forward (DF)-assisted framework called DF-RS. Through simulation results, it is shown that the proposed framework outperforms the corresponding DF-RS, RS without IRS and IRS-assisted conventional non-orthogonal multiple access (NOMA) schemes. Furthermore, the impact of various system's parameters such as the number of IRS reflecting elements and the number of users on the system performance is revealed.

中文翻译：

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用于智能反射表面辅助多用户通信的速率分割多路访问

由于智能反射面 (IRS) 能够重新配置无线传播环境，它最近已成为 6G 无线系统的一项有前途的技术。在本文中，我们研究了用于 IRS 辅助下行链路系统的速率拆分多址 (RSMA)，其中基站 (BS) 在 IRS 的帮助下与单天线用户进行通信。RSMA 依赖于 BS 的速率分离 (RS) 和用户的连续干扰消除 (SIC)，并提供了一个通用的多址框架。我们衍生出一种称为 IRS-RS 的新架构，它利用了 RS 和 IRS 之间的相互作用。对于性能分析，我们利用开关控制技术来控制 IRS-RS 的无源波束成形矢量，并推导出小区边缘用户和附近用户中断概率的闭式表达式。而且，我们还分析了小区边缘用户对于足够多的反射元素的中断行为。此外，我们还分析了称为 DF-RS 的基于协作 RS 的解码转发 (DF) 辅助框架的中断性能。通过仿真结果表明，所提出的框架优于相应的 DF-RS、无 IRS 的 RS 和 IRS 辅助的常规非正交多址 (NOMA) 方案。此外，还揭示了各种系统参数，如IRS 反射元件的数量和用户数量对系统性能的影响。通过仿真结果表明，所提出的框架优于相应的 DF-RS、无 IRS 的 RS 和 IRS 辅助的常规非正交多址 (NOMA) 方案。此外，还揭示了各种系统参数，如IRS 反射元件的数量和用户数量对系统性能的影响。通过仿真结果表明，所提出的框架优于相应的 DF-RS、无 IRS 的 RS 和 IRS 辅助的常规非正交多址 (NOMA) 方案。此外，还揭示了各种系统参数，如IRS 反射元件的数量和用户数量对系统性能的影响。