Rate splitting multiple access (RSMA) and non-orthogonal multiple access (NOMA) are the key enabling multiple access techniques to enable massive connectivity. However, it is unclear whether RSMA would consistently outperform NOMA from a system sum-rate perspective, users' fairness, as well as convergence and feasibility of the resource allocation solutions. This paper investigates the weighted sum-rate maximization problem to optimize power and rate allocations in a hybrid RSMA-NOMA network. In the hybrid RSMA-NOMA, by optimally allocating the maximum power budget to each scheme, the BS operates on NOMA and RSMA in two orthogonal channels, allowing users to simultaneously receive signals on both RSMA and NOMA. Based on the successive convex approximation (SCA) approach, we jointly optimize the power allocation of users in NOMA and RSMA, the rate allocation of users in RSMA, and the power budget allocation for NOMA and RSMA considering successive interference cancellation (SIC) constraints. Numerical results demonstrate the trade-offs that hybrid RSMA-NOMA access offers in terms of system sum rate, fairness, convergence, and feasibility of the solutions.

翻译：速率分割多址接入（RSMA）和非正交多址接入（NOMA）是实现大规模连接的关键使能多址技术。然而，从系统总速率、用户公平性以及资源分配方案的收敛性和可行性角度来看，RSMA是否始终优于NOMA尚不明确。本文研究混合RSMA-NOMA网络中的加权和速率最大化问题，以优化功率和速率分配。在混合RSMA-NOMA中，通过最优分配最大功率预算至每种方案，基站在两个正交信道上分别运行NOMA和RSMA，使用户能够同时接收RSMA和NOMA信号。基于逐次凸近似（SCA）方法，我们联合优化了NOMA和RSMA中用户的功率分配、RSMA中用户的速率分配，以及在考虑串行干扰消除（SIC）约束下NOMA和RSMA的功率预算分配。数值结果展示了混合RSMA-NOMA接入在系统总速率、公平性、收敛性和方案可行性方面提供的权衡。