A data compression apparatus includes a receiver that outputs sampling sequences corresponding to signals obtained by adding different delay times to different signals obtained by branching a target signal into a plurality of lines, and sampling the signals at a sampling rate less than the Nyquist rate, and an encoder that converts the sampling sequences into compressed data. The encoder includes a sub-FFT that converts the sampling sequences into frequency-domain signals, a signal processing unit that performs, at one time, phase compensation processing for sub-Nyquist zones of the sampling sequences, and processing to cancel phase rotation, a target frequency estimator that determines into which sub-Nyquist zone the target signal has been folded and estimates the frequency of the target signal, and an encoding unit that converts a value representing the sub-Nyquist zone and the corresponding amplitude value into the compressed data and output the compressed data.

An embodiment includes generating, by an access point (AP), a trigger frame that solicits a response from one or more stations (STAs), where the trigger frame includes a pre frame check sequence (pre-FCS) field, a padding field, and a frame check sequence (FCS) field, the pre-FCS field preceding the padding field, transmitting, to the one or more STAs, the trigger frame to request the one or more STAs to perform a dynamic sub-band switch operation, and determining whether the dynamic sub-band switch operation is successfully performed at the one or more STAs based on whether or not a response is received from the one or more STAs in response to the trigger frame.