Abstract
This paper studies a cell-free (CF) massive multi-input multi-output (MIMO) simultaneous wireless information and power transmission (SWIPT) system and proposes a user-centric (UC) access point (AP) selection method and a trade-off performance optimization scheme for spectral efficiency and energy efficiency. In this system, users have both energy harvesting and information transmission functions, and according to the difference between energy harvesting and information transmission, a flexible AP selection scheme is designed. This paper analyses the trade-off between energy efficiency and spectral efficiency, proposes an evaluation index that takes into account both energy efficiency and spectral efficiency, and jointly optimizes the AP selection scheme and the uplink (UL) and downlink (DL) time switching ratio to maximize the trade-off performance. Then, the non-convex problem is converted to a geometric planning (GP) problem to solve. The simulation results show that by implementing a suitable AP selection scheme and UL and DL time allocation, the information processing scheme on the AP side has a slight loss in spectral efficiency, but the energy efficiency is close to the performance of global processing on the central processing unit (CPU).
Energy efficiency and spectral efficiency trade-off for OFDM systems with imperfect channel estimation