Fairness of Multi-User in mmWave MIMO-NOMA System with Active RIS

This paper considers a downlink mmWave MIMO-NOMA system-assisted active RIS, where the base station is mounted with multiple antennas and multiple users with single antenna. RIS gain, phase shifts, and users' power are optimized to maximize energy efficiency such that the rate of each user exceeds a desired threshold. The non-convex problem can be solved by applying Dinkelbach's algorithm with fractional programming. The maximization problem is converted to Quadratic Constraint Quadratic programming (QCQP), and the Lagrange augmented method is applied to obtain the optimum RIS elements phase and gain. Jain's fairness index is used to measure the fairness among users. Numerical results show that all users satisfy the rate constraint.