Physical layer frame format for WLAN

1. A method for generating a physical layer (PHY) protocol data unit for transmission via a communication channel, the PHY protocol data unit conforming to a first communication protocol, the method comprising:

generating, at a network interface device, a PHY preamble of the PHY protocol data unit, wherein the PHY preamble is generated to include:

a first field that includes a first set of one or more information bits that indicate a duration of the PHY protocol data unit, the first field being formatted such that the first field is decodable by a receiver device that conforms to a second communication protocol, but does not conform to the first communication protocol, to determine the duration of the PHY protocol data unit based on the first field, and

a second field that includes a second set of one or more information bits that indicate to a receiver device that conforms to the first communication protocol that the data unit conforms to the first communication protocol, and wherein generating the PHY preamble includes one or both of (i) generating the second set of one or more information bits according to an error detection scheme that does not conform to the second communication protocol and (ii) generating the second set of one or more information bits to indicate a PHY mode not supported by the second communication protocol,

wherein generating the PHY preamble includes modulating the PHY preamble onto a first plurality of orthogonal frequency division multiplexing (OFDM) symbols; and

generating, at a network interface device, a PHY data portion of the PHY protocol data.

2. The method of claim 1 , wherein generating the second set of one or more information bits according to the error detection scheme not specified by the second communication protocol comprises generating a cyclic redundancy check (CRC) for the second field according to a CRC polynomial different than a CRC polynomial specified for a corresponding PHY preamble field by the second communication protocol.

3. The method of claim 1 , wherein generating the second set of one or more information bits according to the error detection scheme not specified by the second communication protocol comprises generating a cyclic redundancy check (CRC) for the second field, including:

generating, at the network interface device, a plurality of CRC bits according to a CRC polynomial specified for a corresponding PHY preamble field by the second communication protocol, and

encrypting, at the network interface device, one or more bits of the plurality of CRC bits to generate the CRC for the second field.

4. The method of claim 1 , wherein generating the second set of one or more information bits according to the error detection scheme not specified by the second communication protocol comprises generating a cyclic redundancy check (CRC) for the second field, including:

generating, at the network interface device, a plurality of CRC bits according to a CRC polynomial specified for a corresponding PHY preamble field by the second communication protocol,

selecting, at the network interface device, a subset of the plurality of CRC bits, the subset to be utilized for the CRC for the second field; and

encrypting, at the network interface device, one or more bits in the selected subset of the plurality of CRC bits to generate the CRC for the second field.

5. The method of claim 1 , wherein the second field includes a modulation and coding (MCS) subfield, and wherein generating the second set of one or more information bits to indicate the PHY mode not supported by the second communication protocol includes generating the MCS subfield to indicate a modulation and coding scheme not supported by the second communication protocol.

6. The method of claim 1 , wherein:

the second field includes i) a first set of bits set to a first value, and ii) a second set of bits set to a second value;

the first set of bits corresponds to a first subfield, specified by the second communication, to indicate a first PHY parameter;

the second set of bits corresponds to a second subfield, specified by the second communication protocol, to indicate a second PHY parameter; and

the first value and the second value corresponds to a combination of values of the first PHY parameter and the second PHY parameter not supported by the second communication protocol.

7. The method of claim 1 , wherein the second communication protocol conforms to the Institute for Electrical and Electronics Engineers (IEEE) 802.11ac Standard.

8. The method of claim 7 , wherein the first communication protocol is a communication protocol that supports a higher throughput than the IEEE 802.11ac Standard.

9. An apparatus comprising:

a network interface device having one or more integrated circuit (IC) devices configured to:

generate a physical layer (PHY) preamble of a PHY protocol data unit, wherein the PHY preamble is generated to include:

a first field that includes a first set of one or more information bits that indicate a duration of the PHY protocol data unit, the first field being formatted such that the first field is decodable by a receiver device that conforms to a second communication protocol, but does not conform to the first communication protocol, to determine the duration of the PHY protocol data unit based on the first field, and

a second field that includes a second set of one or more information bits that indicate to a receiver device that conforms to the first communication protocol that the data unit conforms to the first communication protocol, and wherein generating the PHY preamble includes one or both of (i) generating the second set of one or more information bits according to an error detection scheme that does not conform to the second communication protocol and (ii) generating the second set of one or more information bits to indicate a PHY mode not supported by the second communication protocol;

wherein the one or more IC devices are further configured to:

modulate the PHY preamble onto a first plurality of orthogonal frequency division multiplexing (OFDM) symbols, and

generate a PHY data portion of the PHY protocol data.

10. The apparatus of claim 9 , wherein the one or more integrated circuits are further configured to generate the second set of one or more information bits according to the error detection scheme not specified by the second communication protocol at least by generating a cyclic redundancy check (CRC) for the second field according to a CRC polynomial different than a CRC polynomial specified for a corresponding PHY preamble field by the second communication protocol.

11. The apparatus of claim 9 , wherein the one or more integrated circuits are further configured to generate the second set of one or more information bits according to the error detection scheme not specified by the second communication protocol at least by generating a cyclic redundancy check (CRC) for the second field, including:

generating a plurality of CRC bits according to a CRC polynomial specified for a corresponding PHY preamble field by the second communication protocol, and

encrypting one or more bits of the plurality of CRC bits to generate the CRC for the second field.

12. The apparatus of claim 9 , wherein the one or more integrated circuits are further configured to generate the second set of one or more information bits according to the error detection scheme not specified by the second communication protocol at least by generating a cyclic redundancy check (CRC) for the second field, including:

generating a plurality of CRC bits according to a CRC polynomial specified for a corresponding field by the second communication protocol,

selecting a subset of the plurality of CRC, the subset to be utilized for the CRC for the second field; and

encrypting one or more bits in the selected subset of the plurality of CRC bits to generate the CRC for the second field.

13. The apparatus of claim 9 , wherein the second field includes a modulation and coding (MCS) subfield, and wherein the one or more integrated circuits are further configured to generate the second set of one or more information bits to indicate the mode not supported by the second communication protocol at least by generating the MCS subfield to indicate a modulation and coding scheme not supported by the second communication protocol.

14. The apparatus of claim 9 , wherein:

the second field includes i) a first set of bits set to a first value, and ii) a second set of bits set to a second value;

the first set of bits corresponds to a first subfield, specified by the second communication, to indicate a first PHY parameter;

the second set of bits corresponds to a second subfield, specified by the second communication protocol, to indicate a second PHY parameter; and

the first value and the second value corresponds to a combination of values of the first PHY parameter and the second PHY parameter not supported by the second communication protocol.

15. The apparatus of claim 9 , wherein the second communication protocol conforms to the Institute for Electrical and Electronics Engineers (IEEE) 802.11ac Standard.

16. The apparatus of claim 15 , wherein the first communication protocol is a communication protocol that supports a higher throughput than the IEEE 802.11ac Standard.

17. A method, comprising:

receiving, at a wireless network interface device, a physical layer (PHY) protocol data unit;

decoding, at the wireless network interface device, a field of a PHY preamble of the PHY protocol data unit, including decoding a received cyclic redundancy check (CRC) included in the field;

generating, at the wireless network interface device, a first CRC based on the field using a first CRC generation scheme, the first CRC generation scheme, specified by a first communication protocol, for a corresponding field in a PHY preamble format defined by the first communication protocol;

generating, at the wireless network interface device, a second CRC based on the field using a second CRC generation scheme, the second CRC generation scheme specified, specified by a second communication protocol, for a corresponding field in a PHY preamble format defined by the second communication protocol;

comparing, at the wireless network interface device, the received CRC to (i) the first generated CRC and (ii) the second generated CRC; and

determining, at the wireless network interface device, whether the PHY protocol data unit conforms to the second communication protocol based on the comparison of the received CRC to (i) the first generated CRC and (ii) the second generated CRC.

18. The method of claim 17 , wherein:

generating the first CRC comprises generating the first CRC according to a first CRC polynomial, the first CRC polynomial specified for the corresponding field in the PHY preamble format defined by the first communication protocol; and

generating the second CRC comprises generating the second CRC according to a second CRC polynomial, the second CRC polynomial specified for the corresponding field in the PHY preamble format defined by the second communication protocol, wherein the second CRC polynomial is different than the first CRC polynomial.

19. The method of claim 17 , wherein:

generating the first CRC comprises generating the first CRC according to a first CRC polynomial, the first CRC polynomial specified the corresponding field in the PHY preamble format defined by the first communication protocol; and

generating the second CRC comprises:

generating a plurality of CRC bits according to the first CRC polynomial, and

encrypting one or more bits of the plurality of CRC bits to generate the second CRC.

20. The method of claim 17 , wherein:

generating the first CRC comprises generating the first CRC according to a first CRC polynomial, the first CRC polynomial specified for the corresponding field in the PHY preamble format defined by the first communication protocol, and

generating the second CRC comprises:

generating a plurality of CRC bits according to the first CRC polynomial,

selecting a subset of the plurality of CRC bits, the subset to be utilized for the second CRC; and

encrypting one or more bits in the selected subset of the plurality of CRC bits to generate the second CRC.

21. An apparatus, comprising:

a wireless network interface having one or more integrated circuit (IC) devices configured to:

receive a physical layer (PHY) protocol data,

decode a field of a PHY preamble of the PHY protocol data unit, including decoding a received cyclic redundancy check (CRC) included in the field,

generate, based on the field, a first CRC using a first CRC generation scheme, the first CRC generation scheme, specified by a first communication protocol, for a corresponding field in a PHY preamble format defined by the first communication protocol,

generate, based on the field, a second CRC using a second CRC generation scheme, the second CRC generation scheme specified, specified by a second communication protocol, for a corresponding field in a PHY preamble format defined by the second communication protocol,

compare the received CRC to (i) the first generated CRC and (ii) the second generated CRC, and

determine whether the PHY protocol data unit conforms to the second communication protocol based on the comparison of the received CRC to (i) the first generated CRC and (ii) the second generated CRC.

22. The apparatus of claim 21 , wherein the one or more IC devices are further configured to:

generate the first CRC according to a first CRC polynomial, the first CRC polynomial specified for the corresponding field in the PHY preamble format defined by the first communication protocol; and

generate the second CRC according to a second CRC polynomial, the second CRC polynomial specified for the corresponding field in the PHY preamble format defined by the second communication protocol, wherein the second CRC polynomial is different than the first CRC polynomial.

23. The apparatus of claim 21 , wherein the one or more IC devices are further configured to:

generate the first CRC according to a first CRC polynomial, the first CRC polynomial specified the corresponding field in the PHY preamble format defined by the first communication protocol; and

generate the second CRC at least by:

generating a plurality of CRC bits according to the first CRC polynomial, and

encrypting one or more bits of the plurality of CRC bits to generate the second CRC.

24. The apparatus of claim 21 , wherein the one or more IC devices are further configured to:

generate the first CRC according to a first CRC polynomial, the first CRC polynomial specified the corresponding field in the PHY preamble format defined by the first communication protocol, and

generate the second CRC at least by:

generating a plurality of CRC bits according to the first CRC polynomial,

selecting a subset of the plurality of CRC bits, the subset to be utilized for the CRC for the second CRC; and

encrypting one or more bits in the selected subset of the plurality of CRC bits to generate the second CRC.