Disclosed is a receiver for configuring a Block Acknowledgement (BA) frame in a wireless communication system for acknowledgement of a data transmission from a transmitter. The receiver receives a Block Acknowledgement Request (BAR) frame in the data transmission from the transmitter and determines an overall size of a bitmap for the BA frame from the BAR frame to acknowledge the data transmission. The receiver configures the BA frame of the response to include the bitmap having the determined overall size, and transmits the configured BA frame to the transmitter. The bitmap of the BA frame includes bits representing reception results of packets of the data transmission received from the transmitter.