Physical layer frame format for WLAN

An apparatus, comprising:

• a wireless network interface device implemented at least partially on one or more integrated circuit (IC) devices, where the one or more IC devices are configured to generate a physical layer (PHY) data unit, including generating a preamble of the PHY data unit, and wherein:
• the preamble is generated to include a first legacy portion and a first non-legacy portion that follows the first legacy portion,
• the first non-legacy portion is generated to include i) a first orthogonal frequency division multiplexing (OFDM) symbol that immediately follows the first legacy portion and that is modulated using binary phase shift keying (BPSK), and ii) a second OFDM symbol that immediately follows the first OFDM symbol and that is modulated using BPSK modulation rotated by 90 degrees (Q-BPSK),
• the first OFDM symbol being modulated using BPSK modulation and the second OFDM symbol being modulated using Q-BPSK indicate to a receiver device that conforms to the first communication protocol that the data unit conforms to the first communication protocol,
• the first non-legacy portion is generated to further include fields that follow the second OFDM symbol and that conform to the first communication protocol,
• a second communication protocol defines a preamble format that includes i) a second legacy portion corresponding to the first legacy portion, and ii) a second non-legacy portion that follows the second legacy portion, the second communication protocol specifying that a third OFDM symbol that immediately follows the second legacy portion is modulated using Q-BPSK, and
• the first OFDM symbol is modulated using BPSK modulation to cause a receiver device that conforms to the second communication protocol to determine that the PHY data unit conforms to a third communication protocol that is different than the first communication protocol and the second communication protocol;
• wherein the one or more IC devices are further configured to control the wireless network interface device to transmit the PHY data unit via a communication channel.