Transmission design for uplink multi-group MIMO–NOMA with finite blocklength

Non-orthogonal multiple access (NOMA) with multiple-input multiple-output (MIMO) is one of the promising candidates to support massive connectivity and improve spectral efficiency for wireless communications. To apply MIMO–NOMA in practical applications, finite blocklength has to be considered. In this article, we explore the finite blocklength transmission design for uplink MIMO–NOMA with group successive interference cancellation (GSIC). We employ the effective throughput as the performance metric to balance the transmission rate and error performance in the finite blocklength regime. To maximize the system effective throughput, we formulate a joint optimization problem of the precoding vectors, equalization vectors, and transmission rates. Since this joint resource allocation is complex and non-convex, we decompose it into two subproblems, i.e., the joint transceiver design and transmission rate adaptation. We first propose an effective algorithm based on the principles of successive convex approximation (SCA) and alternating optimization to provide a joint transceiver design. Then, we derive a semi-closed-form solution of the optimal transmission rates and develop an iterative algorithm to adapt the transmission rates for all the users. Finally, we propose a joint resource allocation algorithm based on block coordinate descent (BCD). Simulation results demonstrate the performance gains by optimizing the transceiver design and transmission rates, which proves the superiority of the proposed algorithm.