A wireless communication apparatus performs bi-directional communication with an initiator. The apparatus is allocated an allocation period for data transmission from the initiator. The apparatus includes means for generating a first physical frame including an acknowledgement frame with respect to data received from the initiator, and generating a second physical frame in which a plurality of transmission data frames addressed to the initiator are aggregated. The apparatus also includes means for transmitting the first physical frame at a first transmission rate and the second physical frame at a second transmission rate, during the allocation period.