Method and device for transmitting data

1. 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 First Signal field, a Second Signal field, and a data portion;

wherein the First Signal field comprises 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);

wherein the Second Signal field comprising information identifying a first sub-channel carrying the at least one A-MPDU for the receiving station;

wherein

the First Signal field is phase-rotated over at least one first subcarrier group, each first subcarrier group having bandwidth of 20 MHz within the operating bandwidth, and

the Second Signal field is phase rotated over a plurality of second subcarrier groups, each second subcarrier group having bandwidth that is less than 20 MHz within the operating bandwidth;

determining a type of block acknowledgement requested, the block acknowledgement indicating a successful receipt of the at least one A-MPDU by the receiving station;

transmitting, when a first type of acknowledgement is requested, a block acknowledgement over a second sub-channel, the second sub-channel assigned to the receiving station; and

transmitting, when a second type of acknowledgement is requested, a block acknowledgement over the operating bandwidth.

2. The method of claim 1 wherein each A-MPDU of the MU-PPDU is associated with one sub-channel of a plurality of sub-channels within the operating bandwidth and has at least one duration field, and all duration fields in all A-MPDUs associated with the plurality of sub-channels are set to a same value.

3. The method of claim 1 wherein the First Signal field is associated with a first fast Fourier transform (FFT) size and the data portion is associated with a second FFT size; and

wherein the second FFT size is four times the first FFT size.

4. The method of claim 3

wherein the first FFT size is 64 and the second FFT size is 256 when the operating bandwidth is 20 MHz;

wherein the first FFT size is 128 and the second FFT size is 512 when the operating bandwidth is 40 MHz;

wherein the first FFT size is 256 and the second FFT size is 1024 when the operating bandwidth is 80 MHz; and

wherein the first FFT size is 512 and the second FFT size is 2048 when the operating bandwidth is 160 MHz.

5. The method of claim 1 wherein the First Signal field comprises space-time block code (STBC) information, the STBC information having one bit and indicating whether the STBC is applied to the data portion.

6. A device for communicating in a wireless local area network, the device comprising:

a radio frequency module configured to transmit and receive radio signals;

a processor operatively coupled with the radio frequency module; and

memory disposed to said processor, said memory including instructions, when executed by said processor causes the processor to:

process a multi-user physical layer protocol data unit (MU-PPDU) over an operating bandwidth, the MU-PPDU including a First Signal field, a Second Signal field, and a data portion;

wherein the First Signal field comprises 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);

wherein the Second Signal field comprising information identifying a first sub-channel carrying the at least one A-MPDU for the receiving station;

wherein

the First Signal field is phase-rotated over at least one first subcarrier group, each first subcarrier group having bandwidth of 20 MHz within the operating bandwidth, and

the Second Signal field is phase rotated over a plurality of second subcarrier groups, each second subcarrier group having bandwidth that is less than 20 MHz within the operating bandwidth;

determine a type of block acknowledgement requested, the block acknowledgement indicating a successful receipt of the at least one A-MPDU by the device;

cause the radio frequency module to transmit, when a first type of acknowledgement is requested, a block acknowledgement over a second sub-channel, the second sub-channel assigned to the device; and

cause the radio frequency module to transmit, when a second type of acknowledgement is requested, a block acknowledgement over the operating bandwidth.

7. The device of claim 6 wherein each A-MPDU of the MU-PPDU is associated with one sub-channel of a plurality of sub-channels within the operating bandwidth and has at least one duration field, and all duration fields in all A-MPDUs associated with the plurality of sub-channels are set to a same value.

8. The device of claim 6 wherein the First Signal field is associated with a first fast Fourier transform (FFT) size and the data portion is associated with a second FFT size; and

wherein the second FFT size is four times the first FFT size.

9. The device of claim 8

wherein the first FFT size is 64 and the second FFT size is 256 when the operating bandwidth is 20 MHz;

wherein the first FFT size is 128 and the second FFT size is 512 when the operating bandwidth is 40 MHz;

wherein the first FFT size is 256 and the second FFT size is 1024 when the operating bandwidth is 80 MHz; and

wherein the first FFT size is 512 and the second FFT size is 2048 when the operating bandwidth is 160 MHz.

10. The device of claim 6 wherein the First Signal field comprises space-time block code (STBC) information, the STBC information having one bit and indicating whether the STBC is applied to the data portion.