Patent ID: 8774251

Claim:
A method implemented in a communication device configured to generate (i) physical layer (PHY) data units corresponding to a first modulation mode and (ii) PHY data units corresponding to a second modulation mode different than the first modulation mode, the method comprising: generating, in the communication device, a PHY data unit having a channel estimation field (CEF), wherein generating the PHY data unit includes generating a sequence u of the CEF, wherein the sequence u of the CEF (i) includes complementary Golay sequences a and b and (ii) is spread with a first cover code, generating a sequence v of the CEF, wherein the sequence v of the CEF (i) includes the complementary Golay sequences a and b, and (ii) is spread with a second cover code different than the first cover code, and generating the PHY data unit such that, within the CEF of the PHY data unit, (i) the sequence u precedes the sequence v when the PHY data unit corresponds to the first modulation mode, and (ii) the sequence v precedes the sequence u when the PHY data unit corresponds to the second modulation mode; and causing, with the communication device, the PHY data unit to be transmitted via a communication channel.