In some implementations, a device may obtain channel state information (CSI) corresponding to each subcarrier of a plurality of subcarriers in a set of RF transmissions comprising at least the plurality of subcarriers. The device may extract phase information of the CSI corresponding to each subcarrier and determine, for each subcarrier, a frequency spectrum from the phase information of the CSI, where the frequency spectrum comprises phase change values of the CSI corresponding to the respective subcarrier for a plurality of frequencies. The device may determine a breathing rate from the frequency spectrum of the CSI corresponding to a subcarrier set comprising one or more of the subcarriers, the breathing rate corresponding to a phase change value in the frequency spectrum within a predetermined range of frequencies for breathing rates. The device may output an indication of the determined breathing rate.