Non-orthogonal multiple access (NOMA) and multiple-input multiple-output (MIMO) are considered promising techniques to satisfy the demands for high spectrum efficiency and massive connectivity in future wireless communication. In this paper, a novel framework to realize transmission in cell-free massive MIMO-NOMA system with deep integration between MIMO and NOMA is proposed. A new method is developed to divide users into different groups according to their equivalent path loss, and then “group-level successive interference cancellation” (GSIC) is used to cancel the inter-group interference when demodulating the users. Based on the new framework, a rigorous closed-form expression of the achievable sum rate in uplink cell-free massive MIMO-NOMA system is derived. In addition, a parallel iterative method is used to obtain the best power control scheme. Simulations show that the proposed scheme can effectively reduce the total power consumption and outperforms the orthogonal multiple access (OMA) transmission and traditional SIC-NOMA schemes based on user clustering.

非正交多址 (NOMA) 和多输入多输出 (MIMO) 被认为是有前途的技术，可以满足未来无线通信中对高频谱效率和大规模连接的需求。在本文中，提出了一种在 MIMO 和 NOMA 深度集成的无细胞大规模 MIMO-NOMA 系统中实现传输的新框架。提出了一种新的方法，根据用户的等效路径损耗将用户分成不同的组，然后在解调用户时使用“组级连续干扰消除”（GSIC）来消除组间干扰。在新框架的基础上，推导了上行无小区大规模MIMO-NOMA系统可实现和速率的严格封闭式表达式。此外，使用并行迭代方法获得最佳功率控制方案。仿真表明，该方案可以有效降低总功耗，优于正交多址（OMA）传输和基于用户聚类的传统 SIC-NOMA 方案。