An Agile-Beam NOMA Scheme in Millimeter Wave Networks

We propose an agile-beam non-orthogonal multiple access (NOMA) scheme for millimeter wave (mmWave) communication networks. The agile-beam NOMA scheme can flexibly switch between the single/multi-beam NOMA transmission depending on the angular phase difference. In particular, we derive the asymptotic switching point with equal power and antennas resource allocation in a large number of BS antennas, which enables base station (BS) to make preliminary selection on beam mode. Furthermore, the optimization problem of maximizing the achievable sum rate in the agile-beam NOMA scheme is formulated and then decomposed into two subproblems, i.e., maximizing the sum rate in single-beam case and multi-beam case. And the optimal solution of power and antennas allocation is provided. Moreover, the proposed agile-beam NOMA scheme is extended to more general multi-user case. Simulation results verify the effectiveness of the asymptotic switching point compared with exact switching point. With the sum rate obtained by intelligent optimization algorithm as a benchmark, the optimal solution is validated in simulation. In addition, the sum rate with optimal resource allocation achieves significant gain over equal resource allocation.