The cellular network coexisting with device-to-device (D2D) communications has been studied extensively. Reconfigurable intelligent surface (RIS) and non-orthogonal multiple access (NOMA) are promising technologies for the evolution of 5G, 6G and beyond. Besides, sparse code multiple access (SCMA) is considered suitable for next-generation wireless network in code-domain NOMA. In this paper, we consider the RIS-aided uplink SCMA cellular network simultaneously with D2D users. We formulate the optimization problem which aims to maximize the cellular sum-rate by jointly designing D2D users resource block (RB) association, the transmitted power for both cellular users and D2D users, and the phase shifts at the RIS. The power limitation and users communication requirements are considered. The problem is non-convex, and it is challenging to solve it directly. To handle this optimization problem, we propose an efficient iterative algorithm based on block coordinate descent (BCD) method. The original problem is decoupled into three subproblems to solve separately. Simulation results demonstrate that the proposed scheme can significantly improve the sum-rate performance over various schemes.

翻译：移动设备和无线网络中的设备对设备（D2D）通信已被广泛研究。可重构智能表面（RIS）和非正交多址（NOMA）是5G、6G及后续发展的有前途的技术。此外，稀疏码多址（SCMA）被认为适用于代码域NOMA中的下一代无线网络。本文考虑了RIS辅助的上行SCMA蜂窝网络与D2D用户同时存在的情况。我们制定了优化问题，旨在通过联合设计D2D用户的资源块（RB）关联、蜂窝用户和D2D用户的发送功率以及RIS的相位移位，最大化蜂窝总速率。考虑到功率限制和用户通信要求。该问题是非凸的，直接解决很具有挑战性。为了解决这个优化问题，我们提出了一种基于块协调下降（BCD）方法的高效迭代算法。原始问题分解为三个子问题分别解决。仿真结果表明，所提出的方案可以显著提高各种方案的总速率性能。