A Simple Design of IRS-NOMA Transmission

This letter proposes a simple design of intelligent reflecting surface (IRS) assisted non-orthogonal multiple access (NOMA) downlink transmission. In particular, conventional spatial division multiple access (SDMA) is used first at the base station to generate orthogonal beams by using the spatial directions of the near users' channels. Then, IRS-assisted NOMA is used to ensure that additional cell-edge users can also be served on these beams by aligning the cell-edge users' effective channel vectors with the predetermined spatial directions. Both analytical and simulation results are provided to demonstrate the performance of the proposed IRS-NOMA scheme and also study the impact of hardware impairments on IRS-NOMA.