Physical layer data unit format

1. In a wireless communication system wherein communication devices exchange information utilizing data units that conform to a first format, wherein the first format includes a short training field (STF) spread with a first spread code, a method for generating a physical layer (PHY) data unit that conforms to a second format, wherein the PHY data unit is for transmitting PHY information, the method comprising:

generating a first portion of the PHY data unit to indicate the PHY data unit conforms to the second format, wherein the first portion of the PHY data unit includes an STF spread with a second spread code different than the first spread code; and

generating a second portion of the PHY data unit according to the second format, wherein the second portion of the PHY data unit includes PHY information elements not specified by the first format.

2. A method according to claim 1 , wherein the second spread code is a complementary sequence of the first spread code.

3. A method according to claim 2 , wherein the first spread code and the second spread code are complementary Golay sequences a and b, respectively.

4. A method according to claim 3 , wherein:

the STF of the first format includes a plurality of consecutive Golay sequences a; and

the STF of the PHY data unit includes a plurality of consecutive Golay sequences b.

5. A method according to claim 4 , wherein:

the STF of the PHY data unit includes a delimiter field after the plurality of consecutive Golay sequences b; and

the delimiter field includes at least one Golay sequence −b.

6. A method according to claim 5 , wherein a Golay sequence a is included between the STF of the PHY data unit and a channel estimation field (CEF) of the PHY data unit.

7. A method according to claim 2 , wherein:

the first format includes a channel estimation field (CEF); and

the first portion of the PHY data unit includes the CEF field of the first format.

8. A method according to claim 7 , wherein the STF of the PHY data unit includes a delimiter field prior to the CEF field.

9. A method according to claim 8 , wherein the STF of the PHY data unit includes after the delimiter field a cyclic prefix for the CEF field.

10. A method according to claim 8 , wherein:

the second format includes two or more sub-formats; and

the method further comprises generating the delimiter field of the PHY data unit to indicate that the PHY data unit conforms to one of the sub-formats.

11. A method according to claim 10 , wherein one of the sub-formats corresponds to a data unit used in beamforming training.

12. A communication device for use in a wireless communication system, wherein the communication device exchanges information with other communication devices (i) utilizing data units that conform to a first format, wherein the first format includes a short training field (STF) spread with a first spread code, and (ii) utilizing a physical layer (PHY) data unit that conforms to a second format, wherein the PHY data unit is for transmitting PHY information, the communication device comprising:

a PHY data unit generator configured to

generate a first portion of the PHY data unit to indicate the PHY data unit conforms to the second format, wherein the first portion of the PHY data unit includes an STF spread with a second spread code different than the first spread code, and

generate a second portion of the PHY data unit according to the second format, wherein the second portion of the PHY data unit includes PHY information elements not specified by the first format.

13. A communication device according to claim 12 , wherein the second spread code is a complementary sequence of the first spread code.

14. A communication device according to claim 13 , wherein the first spread code and the second spread code are complementary Golay sequences a and b, respectively.

15. A communication device according to claim 14 , wherein:

the STF of the first format includes a plurality of consecutive Golay sequences a; and

the PHY data unit generator is configured to generate the STF of the PHY data unit to include a plurality of consecutive Golay sequences b.

16. A communication device according to claim 15 , wherein:

the PHY data unit generator is configured to generate the STF of the PHY data unit to include a delimiter field after the plurality of consecutive Golay sequences b; and

the delimiter field includes at least one Golay sequence −b.

17. A communication device according to claim 16 , wherein the PHY data unit generator is configured to include a Golay sequence a between the STF of the PHY data unit and a channel estimation field (CEF) of the PHY data unit.

18. A communication device according to claim 12 , further comprising a PHY controller to control the PHY data unit generator during implementation of PHY functions.

19. A communication device according to claim 12 , further comprising a modulator to modulate the PHY data unit.

20. In a wireless communication system wherein communication devices exchange information utilizing data units that conform to a first format, wherein the first format includes a short training field (STF) spread with a first spread code, a method for processing a physical layer (PHY) data unit that conforms to a second format, wherein the second format includes PHY information, the method comprising:

analyzing a first portion of a received data unit to determine whether the received data unit conforms to the second format, wherein

the first portion of the received data unit includes an STF of the received data unit,

analyzing the first portion of the received data unit includes determining whether the STF of the received data unit is an STF conforming to the second format, and

the STF of the second format is spread with a second spread code different than the first spread code; and

when the received data unit is determined to conform to the second format, utilizing PHY information elements in a second portion of the received data unit to perform one or more PHY functions, wherein the PHY information elements are not specified by the first format.

21. A method according to claim 20 , wherein:

the second spread code is a complementary sequence of the first spread code, and

analyzing the first portion of the received data unit comprises determining whether the STF of the received data unit is spread with the second spread code.

22. A method according to claim 21 , wherein:

the first spread code and the second spread code are complementary Golay sequences a and b, respectively; and

determining whether the STF of the received data unit is spread with the second spread code comprises determining whether the STF of the received data unit is spread with the Golay sequence b.

23. A method according to claim 22 , wherein:

the STF of the second format includes a delimiter field after the plurality of consecutive Golay sequences b;

the delimiter field includes at least one Golay sequence −b; and

the method further comprises detecting the delimiter field.

24. A method according to claim 23 , wherein a Golay sequence a is included between the STF of the second format and a channel estimation field (CEF).

25. A method according to claim 20 , wherein:

the PHY information elements include BFT information elements not specified by the first format; and

utilizing the PHY information elements in the second portion of the received data unit includes performing a beamforming training function.

26. A communication device for use in a wireless communication system, wherein the communication device exchanges information with other communication devices (i) utilizing data units that conform to a first format, wherein the first format includes a short training field (STF) spread with a first spread code, and (ii) utilizing physical layer (PHY) data units that conform to a second format, wherein the second format includes PHY information, the communication device comprising:

a PHY data unit detector configured to

analyze a first portion of a received data unit to determine whether the received data unit conforms to the second format, wherein

the first portion of the received data unit includes an STF of the received data unit,

the PHY data unit detector is configured to analyze the first portion of the received data unit at least in part by determining whether the STF of the received data unit is an STF of the second format, and

the STF of the second format is spread with a second spread code different than the first spread code, and

if the received data unit is determined to conform to the second format, utilize PHY information elements in a second portion of the received data unit to perform one or more PHY functions, wherein the PHY information elements are not specified by the first format.

27. A communication device according to claim 26 , wherein the second spread code is a complementary sequence of the first spread code.

28. A communication device according to claim 27 , wherein the first spread code and the second spread code are complementary Golay sequences a and b, respectively.

29. A communication device according to claim 28 , wherein:

the STF of the first format includes a plurality of consecutive Golay sequences a; and

the PHY data unit detector is configured to determine whether the STF of the received data unit includes a plurality of consecutive Golay sequences b.

30. A communication device according to claim 29 , wherein:

the STF of the second format includes a delimiter field after the plurality of consecutive Golay sequences b;

the delimiter field includes at least one Golay sequence −b; and

the PHY data unit detector is configured to detect the delimiter field.

31. A communication device according to claim 26 , further comprising a demodulator to demodulate the received data unit.

32. A communication device according to claim 26 , further comprising a despreader.