On Energy Efficiency of Irregular Intelligent Surface-Aided Cell-Free Massive MIMO Systems

Abstract

Non-cellular base station (BS) technology has become an important means to improve the capacity of wireless communication system because of its strong anti-networking performance. However, in order to further improve the transmission capacity of the network, BSs with higher cost and higher energy consumption must be arranged in the network. Therefore, the use of cheap and easily available reconfigurable intelligent surface (RIS) is a potential energy-saving technology. However, with the increase of the number of RIS units, the channel acquisition cost is getting higher and higher, and the power consumption is also increasing. Therefore, it is very important to use RIS elements to improve the ability of the system. A cell-free (CF) multi-input and multi-output system (MIMO) based on random RIS is studied. This project intends to study a class of network topology and beam optimization problems aiming at the highest energy efficiency. In view of the complexity of the problem, this project intends to split the problem into several sub-problems for cross-iteration, so as to get the sub-optimal results. Simulation experiments show that this method can effectively improve the energy consumption of the system when the number of RIS is limited.