Energy Efficiency Maximization for RIS-Aided Multi-user MISO Systems in Integrated Power Communication Networks

Recently, the integrated power communication network has gained considerable attention, because of new differentiated business. To improve the energy efficiency (EE) for information acquisition services, reconfigurable intelligent surface (RIS) is proposed. Under the constraints of the minimum rate of each user, the maximum transmit power limit of the base station and the unit modulus constraint of the phase angle of RIS, this paper aims for maximizing EE in RIS-aided multiple-input-single-output (MISO) systems. Firstly, the maximum signal-to-interference-noise ratio (SINR), the total power consumption of the system and the phase matrix of RIS are analyzed and derived, and then the optimization problem is established with the beamforming and transmission power of the base station transmitting multi-user as variables. Thirdly, in order to solve the optimization problem, this paper proposes to use the maximum ratio to send pre-coding to maximize the SINR received by users, and uses an improved sine and cosine optimization algorithm to optimize the phase matrix of RIS. Finally, a scheme of alternating iterative optimization of phase matrix and power is designed. Simulation results show that the proposed algorithm is very effective in improving the energy efficiency of the system. Compared with the traditional relay amplification scheme, the improved SCA optimization scheme achieves about 30% improvement in energy efficiency, which confirms the feasibility of the proposed method in improving the energy efficiency of MISO system.