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

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

generating, at a first communication device, a trigger frame to trigger an uplink orthogonal frequency multiple access (OFDMA) transmission,

wherein the trigger frame is configured to indicate that multiple second communication devices can contend for a contiguous band of OFDM tones as part of the uplink OFDMA transmission,

wherein the trigger frame includes power control information that includes i) a transmission power value that indicates a transmission power used by the first communication device to transmit the trigger frame and ii) a target received power value that indicates a target received power, at the first communication device, for the uplink OFDMA transmission, and

wherein the power control information, including i) the transmission power value, and ii) the target received power value, is for use by communication devices participating in the uplink OFDMA transmission to determine respective transmission power levels for the uplink OFDMA transmission;

transmitting, with the first communication device, the trigger frame; and

receiving, at the first communication device, the uplink OFDMA transmission in response to the trigger frame.

2. The method of claim 1 , wherein:

a communication protocol, according to which the first communication device and the multiple second communication devices are configured to operate, specifies that all contention-based uplink OFDMA transmissions are to have a predetermined length.

3. The method of claim 1 , wherein:

a communication protocol, according to which the first communication device and the multiple second communication devices are 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.

4. The method of claim 1 , further comprising:

selecting, at the first communication device, the length of the OFDMA transmission from a set of multiple predetermined lengths corresponding to contention-based uplink OFDMA transmissions, wherein the set of multiple predetermined lengths is smaller than a set of possible lengths of uplink OFDMA transmissions that are not contention-based; and

including, at the first communication device, an indication of the selected length in a field of the trigger frame.

5. The method of claim 4 , wherein:

the set of multiple predetermined lengths corresponds to a set of multiple types of contention-based uplink OFDMA transmissions;

selecting the length of the contention-based uplink OFDMA transmission from the set of multiple predetermined lengths comprises selecting, at the first communication device, a type of contention-based uplink OFDMA transmission from the set of multiple types of contention-based uplink OFDMA transmissions; and

including the indication of the selected length in the field of the trigger frame comprises including, at the first communication device, an indication of the selected type of contention-based uplink OFDMA transmission in a field of the trigger frame that is reserved for indicating a type of contention-based uplink OFDMA transmission that the trigger frame is configured to prompt.

6. The method of claim 1 , wherein:

receiving the uplink OFDMA transmission includes receiving a sequence of values included in the uplink OFDMA transmission; and

the method includes processing, at the first communication device, the sequence of values to determine which second communication device transmitted the sequence of values.

7. The method of claim 6 , wherein:

processing the sequence of values comprises correlating, at the first communication device, the sequence of values included in the uplink OFDMA transmission with another sequence corresponding to a particular second communication device.

8. The method of claim 7 , wherein:

the other sequence also corresponds to a particular message from a set of multiple messages; and

the method further comprises determining whether the particular second communication device conveyed the particular message based on a result of correlating the sequence of values included in the contention-based uplink OFDMA transmission with the other sequence.

9. An apparatus, comprising:

a network interface device associated with a first communication device, the network interface device having one or more integrated circuits configured to:

generate a trigger frame to trigger an uplink orthogonal frequency multiple access (OFDMA) transmission,

wherein the trigger frame is configured to indicate that multiple second communication devices can contend for a contiguous band of OFDM tones as part of the uplink OFDMA transmission,

wherein the trigger frame includes power control information that includes i) a transmission power value that indicates a transmission power used by the first communication device to transmit the trigger frame and ii) a target received power value that indicates a target received power, at the first communication device, for the uplink OFDMA transmission, and

wherein the power control information, including i) the transmission power value, and ii) the target received power value, is for use by communication devices participating in the uplink OFDMA transmission to determine respective transmission power levels for the uplink OFDMA transmission;

transmit the trigger frame; and

receive the uplink OFDMA transmission.

10. The apparatus of claim 9 , wherein:

a communication protocol, according to which the first communication device and the multiple second communication devices are configured to operate, specifies that all contention-based uplink OFDMA transmissions are to have a predetermined length.

11. The apparatus of claim 9 , wherein:

a communication protocol, according to which the first communication device and the multiple second communication devices are 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.

12. The apparatus of claim 9 , wherein the one or more integrated circuits are further configured to:

select a length of the uplink OFDMA transmission from a set of multiple predetermined lengths corresponding to contention-based uplink OFDMA transmissions, wherein the set of multiple predetermined lengths is smaller than a set of possible lengths of uplink OFDMA transmissions that are not contention based; and

include an indication of the selected length in a field of the trigger frame.

13. The apparatus of claim 12 , wherein:

the set of multiple predetermined lengths corresponds to a set of multiple types of contention-based uplink OFDMA transmissions; and

the one or more integrated circuits are further configured to:

select a type of contention-based uplink OFDMA transmission from the set of multiple types of contention-based uplink OFDMA transmissions, and

include an indication of the selected type of contention-based uplink OFDMA transmission in a field of the trigger frame that is reserved for indicating a type of contention-based uplink OFDMA transmission that the trigger frame is configured to prompt.

14. The apparatus of claim 9 , wherein the one or more integrated circuits are further configured to:

receive a sequence of values included in the uplink OFDMA transmission; and

process the sequence of values to determine which second communication device transmitted the sequence of values.

15. The apparatus of claim 14 , wherein the one or more integrated circuits are further configured to:

correlate the sequence of values included in the uplink OFDMA transmission with another sequence corresponding to a particular second communication device; and

determine whether the particular second communication device transmitted the sequence of values based on a result of correlating the sequence of values included in the uplink OFDMA transmission with the other sequence.

16. The apparatus of claim 15 , wherein:

the other sequence also corresponds to a particular message from a set of multiple messages; and

the one or more integrated circuits are further configured to determine whether the particular second communication device conveyed the particular message based on the result of correlating the sequence of values included in the uplink OFDMA transmission with the other sequence.