Physical layer frame format for WLAN

• US 10,382,598 B1
• Filed: 09/14/2016
• Issued: 08/13/2019
• Est. Priority Date: 05/01/2015
• Status: Active Grant

• Current Assignee: Marvell Asia Pte Limited (Marvell Technology Group Limited)
• Original Assignee: Marvell International Limited (Marvell Technology Group Limited)
• Inventors: Zhang, Hongyuan, Sun, Yakun, Wang, Lei
• Primary Examiner(s): Mohebbi, Kouroush
• Application Number:
  US15/265,614
• Time in Patent Office: 1,063 Days
• Field of Search: None
• CPC Class Codes: H04L 25/0226 sounding signals per se
• CPC Class Codes: H04L 27/2602 Signal structure
• CPC Class Codes: H04L 27/2603 Signal structure ensuring backward compatibility with legacy system
• CPC Class Codes: H04L 27/261 Details of reference signals
• CPC Class Codes: H04L 69/18 Multiprotocol handlers, e.g. single devices capable of handling multiple protocols
• CPC Class Codes: H04L 69/22 Parsing or analysis of headers
• CPC Class Codes: H04W 28/04 Error control
• CPC Class Codes: H04W 28/06 Optimizing the usage of the radio link, e.g. header compression, information sizing , discarding information system modifying transmission characteristic according to link quality by modifying frame length H04L1/0007; dynamic adaptation of the packet size for flow control or congestion control H04L47/365
• CPC Class Codes: H04W 84/12 WLAN [Wireless Local Area Networks]

Abstract

A first format according to which a PHY data unit is to be generated is selected. The data unit is generated according to the first format, including generating a PHY preamble of the PHY data unit to include a first field and a second field. The PHY preamble is generated so that one or more OFDM symbols are rotated by 90 degrees with respect to other OFDM symbols in the PHY preamble to signal the first format. Or, the first field is generated to include a set of bits that according to an error detection scheme that does not conform to a second format; or the set of information bits indicates a mode not supported in connection with the second format. Or, a duplicate of at least one of the first field and the second field is included in the PHY preamble, to signal the first format.

Claims

1. A method for generating a data unit for transmission via a communication channel, the method comprising:

selecting, at a communication device, a first format according to which the data unit is to be generated, the first format selected from a plurality of formats;

selecting, at the communication device, a pilot sequence to be used for generating the data unit, wherein

the pilot sequence is selected from a plurality of pilot sequences corresponding to the plurality of data unit formats,

the pilot sequence is selected based on the selected first data unit format,

selecting the pilot sequence includes selecting a parameter c_n,k based on the selected first data unit format,

c_n,k is a sequence for an n-th orthogonal frequency division multiplexing (OFDM) symbol, and

k is an OFDM subcarrier index;

generating, at the communication device, the data unit according to the first format, including generating a physical layer (PHY) preamble according to the first format, wherein generating the PHY preamble includes generating the PHY preamble to include a first signal field and a second signal field, and wherein generating the PHY preamble further includes;

generating one or more OFDM symbols of the PHY preamble according to the sequence c_n,k, and

generating the PHY preamble to include the selected pilot sequence, modulated on one or more pilot subcarriers, in the one or more OFDM symbols; and

wherein generating the PHY preamble further includes at least one of;

i) generating the PHY preamble so that one or more orthogonal frequency division multiplexing (OFDM) symbols are rotated by 90 degrees with respect to other OFDM symbols in the PHY preamble,

ii) generating, at the communication device, the first signal field to include a set of one or more information bits, and wherein generating the first signal field includes one or both of (a) generating the set of one or more information bits according to an error detection scheme that does not conform to a second format, and (b) generating the set of one or more information bits to indicate a mode not supported in connection with the second format, and

iii) including, at the communication device, a duplicate of at least one of the first signal field and the second signal field in the PHY preamble,

wherein the presence of the selected pilot sequence, modulated on the one or more pilot subcarriers, in the one or more OFDM symbols of the PHY preamble, and the at least one of;

i) the one or more OFDM symbols that are rotated by 90 degrees with respect to the other OFDM symbols in the PHY preamble,

ii) the set of one or more information bits in the first signal field in the PHY preamble that is at least one of (a) generated according to the error detection scheme that does not conform to the second format, and (b) indicates the mode not supported in connection with the second format, and

iii) the duplicate of the at least one of the first signal field and the second signal field in the PHY preamble,

indicates to receiver devices that the data unit conforms to the first format among the plurality of formats.

2. The method of claim 1, wherein:

at least some of the plurality of data unit formats correspond to different communication protocols;

the first format corresponds to a first communication protocol and a second format corresponds to a second communication protocol; and

at least one of

i) the error detection scheme does not conform to the second communication protocol,

ii) the set of one or more information bits are generated to indicate a mode not supported by the second communication protocol,

iii) preambles of data units that conform to the second communication protocol do not include a duplicate of the first signal field nor a duplicate of the second signal field, and

iv) the second communication protocol does not specify that the one or more OFDM symbols are rotated by 90 degrees with respect to other OFDM symbols in the PHY preamble.

3. The method of claim 2, wherein:

the second signal field follows the first signal field in the PHY preamble; and

at least one of;

i) the error detection scheme does not conform to the second communication protocol, and

ii) the set of one or more information bits are generated to indicate a mode not supported by the second communication protocol.

4. The method of claim 2, wherein:

preambles of data units that conform to the second format do not include the selected pilot sequence.

5. The method of claim 4, wherein:

the first communication protocol defines a third format different than the first format; and

at least one of

i) the error detection scheme does not conform to the second communication protocol,

ii) the error detection scheme does not conform to the third format,

iii) the set of one or more information bits are generated to indicate a mode not supported by the second communication protocol,

iv) the set of one or more information bits are generated to indicate a mode not supported by the third format,

v) the second communication protocol does not specify that the one or more OFDM symbols are rotated by 90 degrees with respect to other OFDM symbols in the PHY preamble,

vi) the third format does not specify that the one or more OFDM symbols are rotated by 90 degrees with respect to other OFDM symbols in the PHY preamble, and

vii) preambles of data units conforming to the third format do not include the selected pilot sequence.

6. An apparatus, comprising:

a network interface device having one or more integrated circuits (ICs) configured to;

select a first format according to which a data unit is to be generated, the first format selected from a plurality of formats, and

select a pilot sequence to be used for generating the data unit, wherein

the pilot sequence is selected from a plurality of pilot sequences corresponding to the plurality of data unit formats,

the pilot sequence is selected based on the selected first data unit format,

selecting the pilot sequence includes selecting a parameter c_n,k based on the selected first data unit format,

c_n,k is a sequence for an n-th orthogonal frequency division multiplexing (OFDM) symbol, and

k is an OFDM subcarrier index;

wherein the one or more ICs are further configured to;

generate the data unit according to the first format, including generating a physical layer (PHY) preamble according to the first format, wherein generating the PHY preamble includes generating the PHY preamble to include a first signal field and a second signal field, and wherein generating the PHY preamble further includes;

generating one or more OFDM symbols of the PHY preamble according to the sequence c_n,k, and

generating the PHY preamble to include the selected pilot sequence, modulated on one or more pilot subcarriers, in the one or more OFDM symbols; and

wherein generating the PHY preamble further includes, at least one of;

i) generating the PHY preamble so that one or more orthogonal frequency division multiplexing (OFDM) symbols are rotated by 90 degrees with respect to other OFDM symbols in the PHY preamble,

ii) generating the first signal field to include a set of one or more information bits, and wherein generating the first signal field includes one or both of (a) generating the set of one or more information bits according to an error detection scheme that does not conform to a second format, and (b) generating the set of one or more information bits to indicate a mode not supported in connection with the second format, and

iii) including a duplicate of at least one of the first signal field and the second signal field in the PHY preamble,

wherein the presence of the selected pilot sequence, modulated on the one or more pilot subcarriers, in the one or more OFDM symbols of the PHY preamble, and the at least one of;

i) the one or more OFDM symbols that are rotated by 90 degrees with respect to the other OFDM symbols in the PHY preamble,

ii) the set of one or more information bits in the first signal field in the PHY preamble that is at least one of (a) generated according to the error detection scheme that does not conform to the second format, and (b) indicates the mode not supported in connection with the second format, and

iii) the duplicate of the at least one of the first signal field and the second signal field in the PHY preamble,

indicates to receiver devices that the data unit conforms to the first format among the plurality of formats.

7. The apparatus of claim 6, wherein:

at least some of the plurality of data unit formats correspond to different communication protocols;

the first format corresponds to a first communication protocol and a second format corresponds to a second communication protocol; and

at least one of

i) the error detection scheme does not conform to the second communication protocol,

ii) the set of one or more information bits are generated to indicate a mode not supported by the second communication protocol,

iii) preambles of data units that conform to the second communication protocol do not include a duplicate of the first signal field nor a duplicate of the second signal field, and

iv) the second communication protocol does not specify that the one or more OFDM symbols are rotated by 90 degrees with respect to other OFDM symbols in the PHY preamble.

8. The apparatus of claim 7, wherein:

the second signal field follows the first signal field in the PHY preamble; and

at least one of;

i) the error detection scheme does not conform to the second communication protocol, and

ii) the set of one or more information bits are generated to indicate a mode not supported by the second communication protocol.

9. The apparatus of claim 7, wherein:

wherein preambles of data units that conform to the second format do not include the selected pilot sequence.

10. The apparatus of claim 9, wherein:

the first communication protocol defines a third format different than the first format; and

at least one of

i) the error detection scheme does not conform to the second communication protocol,

ii) the error detection scheme does not conform to the third format,

iii) the set of one or more information bits are generated to indicate a mode not supported by the second communication protocol,

iv) the set of one or more information bits are generated to indicate a mode not supported by the third format,

v) the second communication protocol does not specify that the one or more OFDM symbols are rotated by 90 degrees with respect to other OFDM symbols in the PHY preamble,

vi) the third format does not specify that the one or more OFDM symbols are rotated by 90 degrees with respect to other OFDM symbols in the PHY preamble, and

vii) preambles of data units conforming to the third format do not include the selected pilot sequence.

11. A method, comprising:

receiving, at a communication device, a data unit via a communication channel, wherein the data unit includes a physical layer (PHY) preamble, and wherein the PHY preamble further includes a first signal field and a second signal field;

determining, at the communication device, a pilot sequence modulated on one or more pilot subcarriers of one or more orthogonal frequency division multiplexing (OFDM) symbols of the PHY preamble; and

determining, at the communication device, a format of the data unit from among a plurality of formats that the communication device is configured to recognize, wherein determining the format of the data unit includes identifying, at the communication device, the pilot sequence, modulated on the one or more pilot subcarriers, of the PHY preamble from a plurality of pilot sequences corresponding to a plurality of data unit formats, wherein identifying the pilot sequence comprises identifying a sequence c_n,k, wherein n is an OFDM symbol index and k is an OFDM subcarrier index;

wherein determining the format of the data unit further includes at least one of;

i) determining whether one or more orthogonal frequency division multiplexing (OFDM) symbols in the PHY preamble are rotated by 90 degrees with respect to other OFDM symbols in the PHY preamble, wherein PHY preambles according to the format include the one or more OFDM symbols rotated by 90 degrees, and PHY preambles of one or more other formats do not include the one or more OFDM symbols rotated by 90 degrees,

ii) determining whether a set of one or more information bits in the first signal field is at least one of (a) generated according to an error detection scheme specified by the format and not specified by one or more other formats, and (b) indicates a mode supported by the format and not supported by one or more other formats, and

iii) determining whether the PHY preamble includes a duplicate of at least one of the first signal field and the second signal field, wherein PHY preambles according to the format include the duplicate of the at least one of the first signal field and the second signal field, and PHY preambles of one or more other formats do not include the duplicate of the at least one of the first signal field and the second signal field.

12. The method of claim 11, wherein:

the format corresponds to a first communication protocol and one or more other formats correspond to one or more second communication protocols;

determining the format of the data unit includes at least one of

i) determining that the error detection scheme conforms to the first communication protocol and does not conform to at least one of the one or more other second communication protocols,

ii) determining that the set of one or more information bits indicate a mode supported by the first communication protocol and not supported by at least one of the one or more other second communication protocols,

iii) determining that the PHY preamble includes the duplicate of at least one of the first signal field and the second signal field, wherein preambles of data units that conform to at least one of the one or more other second communication protocols do not include a duplicate of the first signal field nor a duplicate of the second signal field, and

iv) determining that one or more OFDM symbols in the PHY preamble are rotated by 90 degrees with respect to other OFDM symbols in the PHY preamble, wherein at least one of the one or more other second communication protocols does not specify that the one or more OFDM symbols are rotated by 90 degrees with respect to other OFDM symbols in the PHY preamble.

13. The method of claim 12, wherein:

the second signal field follows the first signal field in the PHY preamble; and

determining the format of the data unit includes at least one of;

i) determining that the set of one or more information bits in the first signal field is generated according the error detection scheme, wherein the error detection scheme does not conform to at least one of the second communication protocols, and

ii) determining that the set of one or more information bits indicate a mode not supported by at least one of the second communication protocols.

14. The method of claim 12, wherein:

preambles of data units that conform to at least one of the second communication protocols do not include the pilot sequence.

15. The method of claim 14, wherein:

the format is a first format;

the first communication protocol defines a second format different than the first format; and

at least one of

i) the error detection scheme does not conform to at least one of the second communication protocols,

ii) the error detection scheme does not conform to the second format,

iii) the set of one or more information bits are generated to indicate a mode not supported by at least one of the second communication protocols,

iv) the set of one or more information bits are generated to indicate a mode not supported in connection with the second format,

v) at least one of the second communication protocols does not specify that the one or more OFDM symbols are rotated by 90 degrees with respect to other OFDM symbols in the PHY preamble,

vi) the second format does not specify that the one or more OFDM symbols are rotated by 90 degrees with respect to other OFDM symbols in the PHY preamble, and

vii) preambles of data units conforming to the second format do not include the pilot sequence.

16. An apparatus, comprising:

a network interface device having one or more integrated circuits (ICs) configured to;

receive a data unit via a communication channel, wherein the data unit includes a physical layer (PHY) preamble of the data unit, and wherein the PHY preamble further includes a first signal field and a second signal field,

determine a pilot sequence modulated on one or more pilot subcarriers of one or more orthogonal frequency division multiplexing (OFDM) symbols of the PHY preamble, and

determine a format of the data unit from among a plurality of formats that the communication device is configured to recognize, wherein determining the format includes identifying, at the communication device, the pilot sequence, modulated on the one or more pilot subcarriers, of the PHY preamble from a plurality of pilot sequences corresponding to a plurality of data unit formats, wherein identifying the pilot sequence comprises identifying a sequence c_n,k, wherein n is an OFDM symbol index and k is an OFDM subcarrier index;

wherein determining the format of the data unit further includes at least one of;

i) determining whether one or more orthogonal frequency division multiplexing (OFDM) symbols in the PHY preamble are rotated by 90 degrees with respect to other OFDM symbols in the PHY preamble, wherein PHY preambles according to the format include the one or more OFDM symbols rotated by 90 degrees, and PHY preambles of one or more other formats do not include the one or more OFDM symbols rotated by 90 degrees,

ii) determining whether a set of one or more information bits in the first signal field is at least one of (a) generated according to an error detection scheme specified by the format and not specified by one or more other formats, and (b) indicates a mode supported by the format and not supported by one or more other formats, and

iii) determining whether the PHY preamble includes a duplicate of at least one of the first signal field and the second signal field, wherein PHY preambles according to the format include the duplicate of the at least one of the first signal field and the second signal field, and PHY preambles of one or more other formats do not include the duplicate of the at least one of the first signal field and the second signal field.

17. The apparatus of claim 16, wherein:

the format corresponds to a first communication protocol and one or more other formats correspond to one or more second communication protocols;

the one or more ICs are configured to at least one of

i) determine that the error detection scheme conforms to the first communication protocol and does not conform to at least one of the one or more other second communication protocols,

ii) determine that the set of one or more information bits are generated to indicate a mode supported by the first communication protocol and not supported by at least one of the one or more other second communication protocols,

iii) determine that the PHY preamble includes the duplicate of the first signal field or the duplicate of the second signal field, wherein preambles of data units that conform to at least one of the one or more other second communication protocols do not include a duplicate of the first signal field nor a duplicate of the second signal field, and

iv) determine that one or more OFDM symbols in the PHY preamble are rotated by 90 degrees with respect to other OFDM symbols in the PHY preamble, wherein at least one of the one or more other second communication protocols does not specify that the one or more OFDM symbols are rotated by 90 degrees with respect to other OFDM symbols in the PHY preamble.

18. The apparatus of claim 17, wherein:

the second signal field follows the first signal field in the PHY preamble; and

the one or more ICs are configured to at least one of;

i) determine whether the set of one or more information bits in the first signal field is generated according the error detection scheme, wherein the error detection scheme does not conform to at least one of the second communication protocols, and

ii) determine whether the set of one or more information bits indicate a mode not supported by at least one of the second communication protocols.

19. The apparatus of claim 17, wherein:

preambles of data units that conform to at least one of the second communication protocols do not include the pilot sequence.

20. The apparatus of claim 19, wherein:

the format is a first format;

the first communication protocol defines a second format different than the first format; and

at least one of

i) the error detection scheme does not conform to at least one of the second communication protocols,

ii) the error detection scheme does not conform to the second format,

iii) the set of one or more information bits are generated to indicate a mode not supported by at least one of the second communication protocols,

iv) the set of one or more information bits are generated to indicate a mode not supported in connection with the second format,

v) at least one of the second communication protocols does not specify that the one or more OFDM symbols are rotated by 90 degrees with respect to other OFDM symbols in the PHY preamble,

vi) the second format does not specify that the one or more OFDM symbols are rotated by 90 degrees with respect to other OFDM symbols in the PHY preamble, and

vii) preambles of data units conforming to the second format do not include the pilot sequence.