User Clustering and Power Allocation for mmWave MIMO-NOMA with IoT devices

Non-orthogonal multiple access (NOMA) has been recently considered in millimeter-wave (mmWave) massive MIMO systems to further enhance the spectrum efficiency. Massive connectivity and low latency are two important challenges for the Internet of Things (IoT) to achieve the quality of service provisions required by the numerous devices. Motivated by these challenges, we propose a power domain mmWave NOMA scheme based on user clustering. In particular, considering the quality of service (QoS) requirements, the machine type communication (MTC) devices are assigned to different ranks in the NOMA cluster, where they are transmitted through the same frequency resource. In this paper, investigate the power allocation problem as a weighted sum rate maximization problem. To solve this non-convex problem with high-dimensional variables, we transform the problem into a convex form by introducing two sets of auxiliary variables. In addition, we propose an iterative algorithm to obtain the optimal solution of power allocation by updating the weight factors and the auxiliary variables. Finally, we give the simulation results to verify the effectiveness of our scheme.