This application provides example data dimension reduction methods, apparatus, and systems, computer devices, and storage mediums, and relates to the communications field. One example method includes receiving an antenna domain received signal, where the antenna domain received signal includes an uplink signal that is received from UE by an array antenna corresponding to an RRS, wherein the antenna domain received signal is a time domain signal, a dimension of the antenna domain received signal is N1, and N1 is an integer greater than 1. A received beam weight is obtained based on channel information of the UE. Dimension reduction is performed on the antenna domain received signal by using the received beam weight to obtain a beam domain received signal, where the beam domain received signal is a frequency domain signal, a dimension of the beam domain received signal is N2, and 0