A wireless communication system, comprising: a central access point, CAP, determining a structure of a current physical frame based on scheduled transmission resources, and transmitting information indicating the structure of the current physical frame in the current physical frame; and, at least one station, STA, communicating with said CAP, according to the information indicating the structure of the current physical frame in the current physical frame, determining the structure of the current physical frame; wherein, a length of each physical frame is determined by its structure, and wherein the length is not fixed; wherein determining the structure of the current physical frame comprises: configuring a preamble sequence used for synchronization of the current physical frame, and configuring a system information channel for transmitting the information indicating the structure of the current physical frame; correspondingly, said CPA sending the preamble sequence, and sending the information indicating the structure of the current physical frame in the system information channel; or wherein determining the structure of the current physical frame comprises: configuring a preamble sequence for synchronization of the current physical frame, and configuring a system information channel used for transmitting the information indicating the structure of the current physical frame; and selectively configuring at least one of a plurality of channels for the current physical frame; correspondingly, said CPA sending said preamble sequence, and sending the information indicating the structure of the current physical frame in the system information channel; and correspondingly, transmitting in the selectively configured channel. a central access point, CAP, determining a structure of a current physical frame based on scheduled transmission resources, and transmitting information indicating the structure of the current physical frame in the current physical frame; and, at least one station, STA, communicating with said CAP, according to the information indicating the structure of the current physical frame in the current physical frame, determining the structure of the current physical frame; wherein, a length of each physical frame is determined by its structure, and wherein the length is not fixed; wherein determining the structure of the current physical frame comprises: configuring a preamble sequence used for synchronization of the current physical frame, and configuring a system information channel for transmitting the information indicating the structure of the current physical frame; correspondingly, said CPA sending the preamble sequence, and sending the information indicating the structure of the current physical frame in the system information channel; or wherein determining the structure of the current physical frame comprises: configuring a preamble sequence for synchronization of the current physical frame, and configuring a system information channel used for transmitting the information indicating the structure of the current physical frame; and selectively configuring at least one of a plurality of channels for the current physical frame; correspondingly, said CPA sending said preamble sequence, and sending the information indicating the structure of the current physical frame in the system information channel; and correspondingly, transmitting in the selectively configured channel. configuring a preamble sequence used for synchronization of the current physical frame, and configuring a system information channel for transmitting the information indicating the structure of the current physical frame; correspondingly, said CPA sending the preamble sequence, and sending the information indicating the structure of the current physical frame in the system information channel; or wherein determining the structure of the current physical frame comprises: configuring a preamble sequence for synchronization of the current physical frame, and configuring a system information channel used for transmitting the information indicating the structure of the current physical frame; and selectively configuring at least one of a plurality of channels for the current physical frame; correspondingly, said CPA sending said preamble sequence, and sending the information indicating the structure of the current physical frame in the system information channel; and correspondingly, transmitting in the selectively configured channel. configuring a preamble sequence for synchronization of the current physical frame, and configuring a system information channel used for transmitting the information indicating the structure of the current physical frame; and selectively configuring at least one of a plurality of channels for the current physical frame; correspondingly, said CPA sending said preamble sequence, and sending the information indicating the structure of the current physical frame in the system information channel; and correspondingly, transmitting in the selectively configured channel.