Embodiments of this application disclose a data receiving method, a data sending method, a data transmission method, and a related apparatus and system. The method includes: sending, by a network device in each transmission subwindow corresponding to a broadcast signal, the broadcast signal to user equipment by using a different antenna port, where the transmission subwindow is obtained by dividing, based on preset subwindow information, a transmission window corresponding to the broadcast signal; and determining, by the UE, a transmission subwindow in which a downlink transmit beam is located; and receiving the broadcast signal in a time in which the transmission subwindow is located, where the time in which the transmission subwindow is located is calculated based on the pre-obtained subwindow information.