The present disclosure relates to data transmission methods, apparatus, and systems. One example base station includes at least one processor and a transceiver. The at least one processor is configured to determine a data transmission resource, where the data transmission resource includes a time-domain transmission resource and a frequency-domain transmission resource. The transceiver is configured to send downlink control information (DCI) to a terminal device, where the DCI indicates the time-domain transmission resource, and perform data transmission with the terminal device on the data transmission resource.