Patent ID: 8885740

Claim:
A method comprising: generating, with a processing device, a first preamble for a first data unit that is to be transmitted via a communication channel, wherein the first preamble includes (i) a first long training field and (ii) a first signal field, wherein the first signal field provides information for interpreting the first data unit, and wherein the first signal field is modulated according to a first modulation technique; generating, with the processing device, the first data unit according to a first data unit format, wherein the first data unit includes the first preamble; generating, with the processing device, a second preamble for a second data unit that is to be transmitted via the communication channel, wherein the second preamble includes a second signal field, the second signal field provides information for interpreting the second data unit, the second preamble includes a second long training field, and generating the second preamble includes at least one of (i) repeating information in the second signal field so that a duration of the second signal field is longer than a duration of the first signal field, and (ii) generating the second long training field so that a duration of the second long training field is longer than a duration of the first long training field, and generating the second preamble includes one of (i) modulating a portion of the second signal field according to a second modulation technique different than the first modulation technique to signal to a receiver that the second data unit is formatted according to a second data unit format different than the first data unit format, and (ii) modulating a portion of the second long training field according to the second modulation technique to signal to the receiver that the second data unit is formatted according to the second data unit format; and generating, with the processing device, the second data unit according to the second data unit format, wherein the second data unit includes the second preamble.