Physical layer frame format for wlan

An apparatus, comprising:

• a wireless local area network (WLAN) physical layer (PHY) unit, the WLAN PHY unit implemented on one or more integrated circuit devices configured to generate a PHY data unit, including generating a preamble of the PHY data unit, wherein
• the preamble includes a legacy field that is formatted that is formatted according to a second communication protocol,
• the preamble includes a signal field having a first orthogonal frequency division multiplexing (OFDM) symbol and a second OFDM symbol,
• the first OFDM symbol (i) immediately follows the legacy field and (ii) is modulated using binary phase shift keying (BPSK) modulation, whereas a third communication protocol specifies that an OFDM symbol, defined by the third communication protocol, that immediately follows the legacy field is modulated using BPSK modulation rotated by 90 degrees (Q-BPSK),
• the second OFDM symbol (i) immediately follows the first OFDM symbol and (ii) is modulated using Q-BPSK to indicate to a receiver device that conforms to the first communication protocol that the data unit conforms to the first communication protocol, and
• the preamble is generated to include further fields that follow the signal field and that conform to the first communication protocol;
• wherein the WLAN PHY unit includes one or more transceivers, implemented on the one or more integrated circuits, wherein the one or more transceivers are configured to transmit the generated data unit via a communication channel.