Contention-based orthogonal frequency division multiple access (OFDMA) communication

1. A method for communicating in a wireless communication network, the method comprising:

receiving, at a communication device, a trigger frame configured to:

trigger a contention-based uplink orthogonal frequency multiple access (OFDMA) transmission by multiple communication devices,

wherein the trigger frame indicates that multiple communication devices can contend for a contiguous band of OFDM tones as part of the contention-based uplink OFDMA transmission, and indicate a length of the contention-based uplink OFDMA transmission,

wherein the trigger frame includes power control information that indicates i) a transmission power of the trigger frame and ii) a target received power for the contention-based uplink OFDMA transmission;

determining, at the communication device, a received power of the trigger frame at the communication device;

determining, at the communication device, a path loss based on the transmission power of the trigger frame and the received power of the trigger frame;

determining, at the communication device, a transmission power level using i) the target received power for the contention-based uplink OFDMA transmission and ii) the path loss;

responsive to receiving the trigger frame, generating, at the communication device, a data unit; and

responsive to receiving the trigger frame, transmitting, with the communication device, the generated data unit at the determined transmission power level as part of the contention-based uplink OFDMA transmission via the contiguous band of OFDM tones.

2. The method of claim 1 wherein the generated data unit has a length indicated by the trigger frame.

3. The method of claim 2 , further comprising:

selecting, at the communication device, the length from a set of multiple predetermined lengths using an indication of the length in a field of the trigger frame;

wherein the set of multiple predetermined lengths corresponds to contention-based uplink OFDMA transmissions, and the set of multiple predetermined lengths is smaller than a set of possible lengths of non-contention-based uplink OFDMA transmissions.

4. The method of claim 1 , wherein:

a communication protocol, according to which the communication device is configured to operate, specifies that all contention-based uplink OFDMA transmissions are to have the length.

5. The method of claim 1 , wherein

a communication protocol, according to which the communication device is configured to operate, specifies that all contention-based uplink OFDMA transmissions are to utilize one or more of i) a predetermined number of spatial streams, ii) a predetermined type of error correction coding, and iii) a predetermined modulation and coding scheme.

6. A method for communicating in a wireless communication network, the method comprising:

receiving, at a communication device, a trigger frame configured to:

trigger a contention-based uplink orthogonal frequency multiple access (OFDMA) transmission by multiple communication devices,

wherein the trigger frame indicates that multiple communication devices can contend for a contiguous band of OFDM tones as part of the contention-based uplink OFDMA transmission, and indicate a length of the contention-based uplink OFDMA transmission,

wherein the trigger frame includes power control information that indicates i) a transmission power of the trigger frame and ii) a target received power for the contention-based uplink OFDMA transmission;

determining, at the communication device, a received power of the trigger frame at the communication device; and

determining, at the communication device, a transmission power level using i) the target received power for the contention-based uplink OFDMA transmission, ii) the transmission power of the trigger frame, iii) and the received power of the trigger frame; and

responsive to receiving the trigger frame, generating, at the communication device, a data unit; and

responsive to receiving the trigger frame, transmitting, with the communication device, the generated data unit at the determined transmission power level as part of the contention-based uplink OFDMA transmission via the contiguous band of OFDM tones.

7. The method of claim 6 wherein the determining at the communication device, the transmission power level includes determining a path loss based on the transmission power of the trigger frame and the received power of the trigger frame.

8. The method of claim 7 wherein the transmission power level is determined based on the path loss and the target received power for the contention-based uplink OFDMA transmission.

9. The method of claim 6 wherein the generated data unit has a length indicated by the trigger frame.

10. The method of claim 9 , further comprising:

selecting, at the communication device, the length from a set of multiple predetermined lengths using an indication of the length in a field of the trigger frame;

wherein the set of multiple predetermined lengths corresponds to contention-based uplink OFDMA transmissions, and the set of multiple predetermined lengths is smaller than a set of possible lengths of non-contention-based uplink OFDMA transmissions.

11. The method of claim 6 , wherein:

a communication protocol, according to which the communication device is configured to operate, specifies that all contention-based uplink OFDMA transmissions are to have the length.

12. The method of claim 6 , wherein

a communication protocol, according to which the communication device is configured to operate, specifies that all contention-based uplink OFDMA transmissions are to utilize one or more of i) a predetermined number of spatial streams, ii) a predetermined type of error correction coding, and iii) a predetermined modulation and coding scheme.