Simultaneously transmitting and reflecting reconfigurable intelligent surface (STAR-RIS) is a promising technology that aids in achieving full-space coverage on both sides of the surface, by splitting the incident signal into transmitted and reflected signals. This paper investigates the resource allocation problem in a STAR-RIS-assisted multi-carrier communication networks. To maximize the system sum-rate, a joint optimization problem comprising of the channel assignment, power allocation, and transmission and reflection beamforming at the STAR-RIS for orthogonal multiple access (OMA) is first formulated. To solve this challenging problem, we first propose a channel assignment scheme utilizing matching theory and then invoke the alternating optimization-based method to optimize the resource allocation policy and beamforming vectors iteratively. Furthermore, the sum-rate maximization problem for non-orthogonal multiple access (NOMA) with flexible decoding orders is investigated. To efficiently solve it, we first propose a location-based matching algorithm to determine the sub-channel assignment, where a transmitted user and a reflected user are grouped on a sub-channel. Based on this transmission-and-reflection sub-channel assignment strategy, a three-step approach is proposed, which involves the optimization of decoding orders, beamforming-coefficient vectors, and power allocation, by employing semidefinite programming, convex upper bound approximation, and geometry programming, respectively. Numerical results unveil that: 1) For OMA, a general design that includes the same-side user-pairing for channel assignment is preferable, whereas for NOMA, the proposed transmission-and-reflection scheme can achieve comparable performance to the exhaustive search-based algorithm. 2) The STAR-RIS-aided NOMA network significantly outperforms networks employing conventional RISs and OMA.

中文翻译：

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STAR-RIS 辅助网络中的资源分配：OMA 和 NOMA


同时发射和反射可重构智能表面（STAR-RIS）是一项很有前途的技术，通过将入射信号分解为发射信号和反射信号，有助于实现表面两侧的全空间覆盖。本文研究了 STAR-RIS 辅助的多载波通信网络中的资源分配问题。为了最大化系统总速率，首先提出了一个联合优化问题，包括正交多址接入 (OMA) 的 STAR-RIS 上的信道分配、功率分配以及传输和反射波束成形。为了解决这个具有挑战性的问题，我们首先利用匹配理论提出一种信道分配方案，然后调用基于交替优化的方法来迭代优化资源分配策略和波束成形向量。此外，还研究了具有灵活解码顺序的非正交多址（NOMA）的和速率最大化问题。为了有效地解决这个问题，我们首先提出一种基于位置的匹配算法来确定子信道分配，其中传输用户和反射用户被分组在子信道上。基于这种传输和反射子信道分配策略，提出了一种三步方法，其中包括通过采用半定规划、凸上界近似和优化解码阶数、波束成形系数向量和功率分配。分别是几何编程。数值结果表明：1）对于 OMA，包括用于信道分配的同侧用户配对的通用设计是优选的，而对于 NOMA，所提出的传输和反射方案可以实现与基于穷举搜索的性能相当的性能。算法。 2) STAR-RIS 辅助的 NOMA 网络显着优于采用传统 RIS 和 OMA 的网络。