A transmission method based on Institute of Electrical and Electronics Engineers (IEEE) 802.11 Multi-User (MU) Multiple-Input and Multiple-Output (MIMO). The method includes transmitting, by a plurality of Virtual Access Points (VAPs), respective acknowledgement requests to stations, wherein at least two of the stations are associated with different VAPs of the plurality of VAPs; and transmitting, by the stations to the VAPs, respective block acknowledgements.