A method for communicating in a wireless local area network, the method comprising: receiving, at a receiving station, a multi-user physical layer protocol data unit, MU-PPDU, over an operating bandwidth, the MU-PPDU including a legacy-short training field, L-STF, a legacy-long training field, L-LTF, a legacy-signal, L-SIG, a signal-A field, an STF, an LTF, a signal-B field, and a data portion, wherein legacy refers to IEEE 802.11a/g standards; wherein the signal-A field includes common control information, comprising bandwidth information, the bandwidth information indicating the operating bandwidth over which the MU-PPDU was received; wherein the data portion comprises at least one aggregated-medium access control, MAC, protocol data units, A-MPDU and all duration fields in the at least one A-MPDU are set to a same value; wherein the signal-B field includes user-specific information, comprising information identifying a first sub-channel carrying the at least one A-MPDU for the receiving station; wherein the STF is used for Automatic Gain Control, AGC, estimation in a Multiple Input Multiple Output, MIMO, transmission; wherein the LTF is used for a MIMO channel estimation; wherein the signal-A field, the L-STF, the L-LTF and the L-SIG are phase-rotated over at least one first subcarrier group using a same multiplication value, each first subcarrier group having bandwidth of 20 MHz within the operating bandwidth, wherein a different multiplication value is usable for an adjacent first subcarrier group, and the signal-B field, the STF, the LTF and the data portion are phase rotated over a plurality of second subcarrier groups using a sequence of different multiplication values, each second subcarrier group having bandwidth that is less than 20 MHz within the operating bandwidth, wherein a number of the at least one first subcarrier group differs from a number of the plurality of second subcarrier groups and the phase rotation of the signal-A field, the L-STF, the L-LTF and the L-SIG differs from the phase rotation of the signal-B field, the STF, the LTF and the data portion in frequency domain; transmitting, according to a first option, a block acknowledgement, the block acknowledgement indicating a successful receipt of the at least one A-MPDU by the receiving station, over a second sub-channel simultaneously to a transmission of another block acknowledgment performed by at least one other receiving station having received the MU-PPDU, the second sub-channel assigned to the receiving station being a part of the operating bandwidth; or transmitting, according to a second option based on a received request, the block acknowledgement over the full operating bandwidth sequentially to a transmission of another block acknowledgment performed by at least one other receiving station having received the MU-PPDU, wherein the signal-A field, L-STF, L-LTF and L-SIG are generated with a first fast Fourier transform, FFT, size and the signal-B field, the STF, the LTF and the data portion are generated with a second FFT size. wherein the signal-A field includes common control information, comprising bandwidth information, the bandwidth information indicating the operating bandwidth over which the MU-PPDU was received; wherein the data portion comprises at least one aggregated-medium access control, MAC, protocol data units, A-MPDU and all duration fields in the at least one A-MPDU are set to a same value; wherein the signal-B field includes user-specific information, comprising information identifying a first sub-channel carrying the at least one A-MPDU for the receiving station; wherein the STF is used for Automatic Gain Control, AGC, estimation in a Multiple Input Multiple Output, MIMO, transmission; wherein the LTF is used for a MIMO channel estimation; wherein the signal-A field, the L-STF, the L-LTF and the L-SIG are phase-rotated over at least one first subcarrier group using a same multiplication value, each first subcarrier group having bandwidth of 20 MHz within the operating bandwidth, wherein a different multiplication value is usable for an adjacent first subcarrier group, and the signal-B field, the STF, the LTF and the data portion are phase rotated over a plurality of second subcarrier groups using a sequence of different multiplication values, each second subcarrier group having bandwidth that is less than 20 MHz within the operating bandwidth, wherein a number of the at least one first subcarrier group differs from a number of the plurality of second subcarrier groups and the phase rotation of the signal-A field, the L-STF, the L-LTF and the L-SIG differs from the phase rotation of the signal-B field, the STF, the LTF and the data portion in frequency domain; transmitting, according to a first option, a block acknowledgement, the block acknowledgement indicating a successful receipt of the at least one A-MPDU by the receiving station, over a second sub-channel simultaneously to a transmission of another block acknowledgment performed by at least one other receiving station having received the MU-PPDU, the second sub-channel assigned to the receiving station being a part of the operating bandwidth; or transmitting, according to a second option based on a received request, the block acknowledgement over the full operating bandwidth sequentially to a transmission of another block acknowledgment performed by at least one other receiving station having received the MU-PPDU, wherein the signal-A field, L-STF, L-LTF and L-SIG are generated with a first fast Fourier transform, FFT, size and the signal-B field, the STF, the LTF and the data portion are generated with a second FFT size.