A method for improving channel utilization of a wireless channel by an access point (201, 202, 301-305, 401-405) comprising: waiting for an indication to transmit aggregated PLCP service data units, PSDUs, to receiving wireless communication stations (201, 202, 301-305, 401-405) in a wireless communication network, wherein the indication comprises at least one of the wireless channel is idle for a predetermined amount of time and an internal timer expired; and obtaining a multi-user, MU, transmitting opportunity, TXOP, for transmitting radio signals to a plurality of wireless communication devices by Orthogonal Frequency Demodulation Multiple Access, OFDMA, transmission, wherein a respective resource unit, RU, is scheduled to each of the plurality of wireless communication devices; characterized by : aggregating data in subframes from multiple queues associated with different access categories to form a single PSDU for generating aggregated PSDUs, wherein the generating comprises aligning the transmission timing of RUs scheduled for the aggregated PSDUs, wherein the aligning comprises aggregating data from multiple access categories into a respective PSDU of the aggregated PSDUs, wherein each access category is associated with a traffic type of the data; and transmitting the aggregated PSDUs to the receiving wireless communication stations (201, 202, 301-305, 401-405), respectively, upon obtaining the indication, wherein the aggregated PSDUs are sent in the MU-TXOP by OFDMA transmission. waiting for an indication to transmit aggregated PLCP service data units, PSDUs, to receiving wireless communication stations (201, 202, 301-305, 401-405) in a wireless communication network, wherein the indication comprises at least one of the wireless channel is idle for a predetermined amount of time and an internal timer expired; and obtaining a multi-user, MU, transmitting opportunity, TXOP, for transmitting radio signals to a plurality of wireless communication devices by Orthogonal Frequency Demodulation Multiple Access, OFDMA, transmission, wherein a respective resource unit, RU, is scheduled to each of the plurality of wireless communication devices; characterized by : aggregating data in subframes from multiple queues associated with different access categories to form a single PSDU for generating aggregated PSDUs, wherein the generating comprises aligning the transmission timing of RUs scheduled for the aggregated PSDUs, wherein the aligning comprises aggregating data from multiple access categories into a respective PSDU of the aggregated PSDUs, wherein each access category is associated with a traffic type of the data; and transmitting the aggregated PSDUs to the receiving wireless communication stations (201, 202, 301-305, 401-405), respectively, upon obtaining the indication, wherein the aggregated PSDUs are sent in the MU-TXOP by OFDMA transmission. aggregating data in subframes from multiple queues associated with different access categories to form a single PSDU for generating aggregated PSDUs, wherein the generating comprises aligning the transmission timing of RUs scheduled for the aggregated PSDUs, wherein the aligning comprises aggregating data from multiple access categories into a respective PSDU of the aggregated PSDUs, wherein each access category is associated with a traffic type of the data; and transmitting the aggregated PSDUs to the receiving wireless communication stations (201, 202, 301-305, 401-405), respectively, upon obtaining the indication, wherein the aggregated PSDUs are sent in the MU-TXOP by OFDMA transmission. <EOS>