1. A data transmission method, comprising:receiving, by a station from an access point, downlink scheduling information and indication information identifying a sequence of the station;
determining, according to the downlink scheduling information, that the station is scheduled by the access point to perform downlink transmission;
before obtaining a downlink scheduling phase, sensing, by the station, whether a channel allocated by the access point associated with the station is occupied;
in response to sensing by the station that the channel is not occupied, sending, by the station, a channel clear signaling to the access point, wherein the channel clear signaling comprises a first identifier identifying the station, and a second identifier identifying the access point, wherein the first identifier comprises the sequence of the station, wherein the sequence of the station is allocated by the access point;
receiving, by the station in the downlink scheduling phase used for data transmission, data transmitted by the access point, the downlink scheduling phase obtained by the access point after the access point determines that the second identifier corresponds to the access point; and
receiving, by the station from the access point, after the station is associated with the access point, a sequence indication update message comprising indication information of an updated sequence of the station.