A client station (STA), when operating in a wireless network, receives data sent by an access point (AP) on a first channel comprising at least one subchannel. During reception of the data on the first channel, the STA monitors channel availability of an additional set of one or more subchannels. In response to a detected availability of at least one newly-available subchannel, the STA sends at least one notification to the AP identifying STA-side availability of the newly-available subchannel(s). The STA subsequently receives data from the AP on the newly-available subchannel(s), which is sent in response to the at least one notification. The AP, when communicating data to the STA, receives the at least one notification from the STA and, in response thereto, initiates data transmission on one or more of the newly-available channel(s).