A suboptimal approach for minimum transmit power NOMA beamforming

In downlink non-orthogonal multiple access (NOMA), beamforming can be employed to effectively mitigate the multiple access interference (MAI) with beamforming gain. It is well-known that user clustering can play a crucial role in simplifying beamforming in NOMA. In this paper, we find the solution to a minimum transmit power beamforming problem for given pair of users in a cluster and propose a simple, but effective user clustering approach in conjunction with the minimum transmit power beamforming.