Non-Orthogonal Multiple Access With Successive Interference Cancellation in Millimeter-Wave Radio-Over-Fiber Systems

We proposed to use the non-orthogonal multiple access (NOMA) scheme in 60-GHz-millimeter-wave radio-over-fiber systems, exploiting the power domain of signals to enable multiuser access, and improve the performance with users under different channel conditions. A DSP-based successive interference cancellation scheme is implemented in the receiver to remove the interference from other users. By this NOMA scheme, the system optimizes the performance of all users as a whole group and dynamically allocates the power resources between different users, such that the reception quality and reliability of the user group is significantly improved compared with current orthogonal frequency-division multiple access. To overcome the user number and security issue raised from NOMA, both orthogonal and NOMA are applied. A nonlinear conjugate gradient method is proposed in the power allocation updating process for fast convergence of the feedback system. With a centralized radio-over-fiber architecture, we enable the millimeter wave system with high-resource utilization rate and better approximation to end users with low cost. A 4-Gb/s downlink system serving three users using 60-GHz band is experimentally demonstrated and measured. The proposed scheme provides larger distance coverage, wider angle tolerance, and better shaded channel tolerance. Better reception quality and reliability are experimentally verified without reducing data rate or increasing transmission power.