Medium access protection and bandwidth negotiation in a wireless local area network

A first communication device, comprising:

• a network interface configured to
• allocate respective sub-channels of an orthogonal frequency division multiplexing (OFDM) channel to two or more second communication devices;
• transmit a first control frame to the two or more second communication devices, wherein the first control frame indicates that the two or more second communication devices are requested to transmit a second control frame to the first communication device;
• receive, from at least some of the two or more second communication devices, respective second control frames, wherein the second control frames are transmitted by the at least some of the two or more second communication devices in the respective sub-channels allocated to the at least some of the second communication devices, and wherein a second control frame transmitted by a particular second communication device indicates that at least a portion of the sub-channel allocated to the second communication device is available, and
• transmit an orthogonal frequency division multiple access (OFDMA) data unit, wherein the OFDMA data unit includes respective OFDM data units transmitted to the at least some of the two or more second communication devices, wherein each OFDM data unit is transmitted to a particular one of the second communication devices in the at least the portion of the sub-channel allocated to the second communication device and indicated to be available by the second control frame received from the second communication device.

A method for protection in a frame exchange between a first communication device and at least one second communication device, the method comprising:

• generating, by a first communication device, a first signal field to be included in a data unit, wherein the first signal field indicates whether a first mode of protection or a second mode of protection is being used for protecting transmission of the data unit, including when the first signal field indicates that the first mode is being utilized, indicating, in a data length sub-field of the first signal field, a length of a data portion of the data unit;
• generating, by the first communication device, a second signal field to be included in a first preamble portion of the data unit, including
• when the first signal field indicates that the first mode of protection is being utilized, indicating in the second signal field, a remaining duration of the frame exchange after the first preamble portion of the data unit, and
• when the first signal field indicates that the second mode of protection is being utilized, indicating, in the second signal field, the length of the data portion of the data unit;
• generating, by the first communication device, the first preamble portion to include at least the second signal field;
• generating, by the first communication device, the data unit to include at least (i) the first preamble portion, (ii) the first signal field, and (iii) the data portion;
• and
• transmitting the data unit from the first communication device to one or more second communication devices.

A first communication device, comprising:

• a network interface configured to
• generate a first signal field to be included in a data unit, wherein the first signal field indicates whether a first mode of protection or a second mode of protection is being used for protecting transmission of the data unit, and wherein when the first signal field indicates that the first mode is being utilized, generating the first signal field includes indicating, in a data length sub-field of the first signal field, a length of a data portion of the data unit;
• generate a second signal field to be included in a first preamble portion of the data unit, including
• when the first signal field indicates that the first mode of protection is being utilized, generating the second signal field includes indicating in the second signal field, a remaining duration of the frame exchange after the first preamble portion of the data unit, and
• when the first signal field indicates that the second mode of protection is being utilized, generating the second signal field includes indicating, in the second signal field, a duration indicative of the length of the data portion of the data unit;
• generate the first preamble portion to include at least the second signal field;
• generate the data unit to include at least (i) the first preamble portion, (ii) the first signal field, and (iii) the data portion;
• and
• transmit the data unit to one or more second communication devices.