Next Generation Multiple Access: Performance Gains From Uplink MIMO-NOMA

The use of multiple-input multiple-output (MIMO) non-orthogonal multiple access (NOMA) based communication protocols is proposed and investigated for the uplink of wireless networks with buffered data-sources, which is the basis of the introduced medium access control (MAC)-layer protocol. To this end, the long-term average throughput is maximized by optimizing the set of users that transmit information at each time slot and their transmit power, the number of packets that are admitted in each user's queue, and the transmission rates, assuming that the instantaneous channel state information is not available at the transmitters. Also, considering a receiver with multiple antennas, two detection techniques are used to mitigate the interference when two users are chosen to simultaneously transmit information in the same resource block, namely successive interference cancellation (SIC) and joint decoding (JD). More specifically, the outage probability for both considered techniques is derived in closed-from, which is a prerequisite for the derivation and the optimization of the throughput. The formulated multi-dimensional long-term stochastic optimization problem is solved by using the Lyapunov framework. Finally, simulation results verify the gains by using MIMO-NOMA as the basis of the next generation multiple access and illustrate the superiority of JD compared to SIC with respect to the number of the receiver's antennas. © 2020 IEEE