Modified preamble structure for IEEE 802.11a extensions to allow for coexistence and interoperability between 802.11a devices and higher data rate, MIMO or otherwise extended devices

• US 7,599,332 B2
• Filed: 05/27/2005
• Issued: 10/06/2009
• Est. Priority Date: 04/05/2004
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Zelst, Albert van, Jones, Vincent K., van Nee, D. J. Richard
• Primary Examiner(s): Le; Danh C
• Application Number:
  US11/140,349
• Publication Number:
  US 20050286474A1
• Time in Patent Office: 1,593 Days
• Field of Search: 370/334, 370/206, 370/350, 375/316
• US Class Current: 370/334
• CPC Class Codes: H04B 7/0671 using different delays between antennas
• CPC Class Codes: H04L 1/06 using space diversity
• CPC Class Codes: H04L 1/0618 Space-time coding
• CPC Class Codes: H04L 25/0212 of impulse response
• CPC Class Codes: H04L 25/0226 sounding signals per se
• CPC Class Codes: H04L 27/261 Details of reference signals
• CPC Class Codes: H04L 27/2613 Structure of the reference signals
• CPC Class Codes: H04W 16/14 Spectrum sharing arrangements between different networks
• CPC Class Codes: H04W 24/00 Supervisory, monitoring or testing arrangements
• CPC Class Codes: H04W 84/12 WLAN [Wireless Local Area Networks]
• CPC Class Codes: H04W 88/06 adapted for operation in multiple networks or having at least two operational modes, e.g. multi-mode terminals
• CPC Class Codes: H04W 99/00 Subject matter not provided for in other groups of this subclass

Abstract

A modified preamble is used by extended devices that operate at higher rates, MIMO or other extensions relative to strict 802.11a-compliant devices. The extended devices might use multiple antenna techniques (MIMO), where multiple data streams are multiplexed spatially and/or multi-channel techniques, where an extended transmitter transmits using more than one 802.11a channel at a time. Such extensions to IEEE 802.11a can exist in extended devices. The modified preamble is usable for signaling, to legacy devices as well as extended devices, to indicate capabilities and to cause legacy devices or extended devices to defer to other devices such that the common communication channel is not subject to unnecessary interference. The modified preamble is also usable for obtaining MIMO channel estimates and/or multi-channel estimates. The modified preamble preferably includes properties that facilitate detection of conventional and/or extended modes (“mode detection”) and provides some level of coexistence with legacy IEEE 802.11a devices.

Claims

1. A method for transmitting a training sequence, the method comprising:

transmitting from at least first and second transmit antennas of a wireless communications system at least first and second preambles configured respectively for transmission from said at least first and second transmit antennas, each of the at least first and second preambles further comprising;

a short training sequence field;

a guard interval field;

a long training sequence field; and

a signal field;

wherein the short training sequence field of the second preamble has a cyclic shift with respect to the short training sequence field of the first preamble;

wherein the long training sequence field of the second preamble has a cyclic shift; and

wherein the signal field of the second preamble has a cyclic shift with respect to the signal of the first preamble.

2. The method of claim 1 wherein only the DC tone of the tones disposed in the long training sequence field of each of the first and second preambles has a zero value.

3. The method of claim 1 wherein the short training sequence field of the second preamble has a cyclic shift of 400 nsec with respect to the short training sequence field of the first preamble, and wherein the long training sequence field of the second preamble has a cyclic shift of 1600 nsec.

4. A method for transmitting a training sequence comprising first, second and third preambles, the method comprising:

transmitting from first, second and third transmit antennas of a wireless communication system a training sequence configured for transmission from said first, second and third transmit antennas, each of the first, second and third preambles further comprising;

a short training sequence field having a duration of 8 μ

sec;

a guard interval field having a duration of 1.6 μ

sec;

a long training sequence field having a duration of 6.4 μ

sec; and

a signal field having a duration of 4 μ

sec;

wherein the short training sequence field of the second preamble has a cyclic shift of 200 nsec with respect to the short training sequence field of the first preamble and wherein the short training sequence field of the third preamble has a cyclic shift of 400 nsec with respect to the short training sequence field of the first preamble;

wherein the long training sequence field of the second preamble has a cyclic shift of 1050 nsec with respect to the long training sequence field of the first preamble and wherein the long training sequence field of the third preamble has a cyclic shift of 2100 nsec with respect to the long training sequence field of the first preamble;

wherein the signal field of the second preamble has a cyclic shift of 1050 nsec with respect to the signal field of the first preamble and wherein the signal field of the third preamble has a cyclic shift of 2100 nsec with respect to the signal field of the first preamble;

wherein only the DC tone of the tones disposed in the long training sequence field of each of the first, second, and third preambles has a zero value.

5. A method for transmitting a training sequence comprising first, second, third, and fourth preambles, the method comprising:

transmitting from first, second, third, and fourth transmit antennas of a wireless communications system a training sequence configured for transmission from said first, second, third and fourth transmit antennas of, each of the first, second, third, and fourth preambles further comprising;

a short training sequence field having a duration of 8 μ

sec;

a guard interval field having a duration of 1.6 μ

sec;

a long training sequence field having a duration of 6.4 μ

sec; and

a signal field having a duration of 4 μ

sec;

wherein the short training sequence field of the second preamble has a cyclic shift of 200 nsec with respect to the short training sequence field of the first preamble, wherein the short training sequence field of the third preamble has a cyclic shift of 400 nsec with respect to the short training sequence field of the first preamble, and wherein the short training sequence field of the fourth preamble has a cyclic shift of 600 nsec with respect to the short training sequence field of the first preamble;

wherein the long training sequence field of the second preamble has a cyclic shift of 800 nsec with respect to the long training sequence field of the first preamble, wherein the long training sequence field of the third preamble has a cyclic shift of 1600 nsec with respect to the long training sequence field of the first preamble, and wherein the long training sequence field of the fourth preamble has a cyclic shift of 2400 nsec with respect to the long training sequence field of the first preamble;

wherein the signal field of the second preamble has a cyclic shift of 800 nsec with respect to the signal field of the first preamble, wherein the signal field of the third preamble has a cyclic shift of 1600 nsec with respect to the signal field of the first preamble, and wherein the signal field of the fourth preamble has a cyclic shift of 2400 nsec with respect to the signal field of the first preamble; and

wherein only the DC tone of the tones disposed in the long training sequence field of each of the first, second, third, and fourth preambles has a zero value.

6. A method for transmitting a training sequence, the method comprising:

transmitting from at least first and second transmit antennas of a wireless communications system at least first and second preambles configured for transmission from said first and second transmit antennas, each of the first and second preambles further comprising;

a short training sequence field;

first and second guard interval fields;

a signal field;

first long training sequence field disposed between the first and second guard interval fields; and

second long training sequence field disposed between the second guard interval field and the signal field, wherein the short training sequence field of the second preamble has a cyclic shift with respect to the short training sequence field of the first preamble;

wherein the first long training sequence field of the second preamble has a cyclic shift with respect to the first long training sequence field of the first preamble;

wherein the second long training sequence field of the second preamble has a cyclic shift with respect to the second long training sequence field of the first preamble; and

wherein the signal field of the second preamble has a cyclic shift with respect to the signal field of the first preamble.

7. The method of claim 6 wherein only the DC tone of the tones disposed in the long training sequence field of each of the first and second long training sequence field of each of the first and second preambles has a zero value.

8. The method of claim 7 further comprising a third preamble configured for transmission from a third transmit antenna of the wireless communication system, the third preamble further comprising:

a short training sequence field;

first and second guard interval fields;

a signal field;

first long training sequence field disposed between the first and second guard interval fields; and

second long training sequence field disposed between the second guard interval field and the signal field, wherein the short training sequence field of the third preamble has a cyclic shift with respect to the short training sequence field of the second preamble;

wherein the first long training sequence field of the third preamble has a cyclic shift with respect to the first long training sequence field of the second preamble;

wherein the second long training sequence field of the third preamble has inverted sign with respect to the second long training sequence field of the first preamble;

wherein the second long training sequence field of the third preamble has a cyclic shift with respect to the second long training sequence field of the second preamble; and

wherein the signal field of the third preamble has a cyclic shift with respect to the signal field of the second preamble.

9. The method of claim 8 further comprising a fourth preamble configured for transmission from a fourth transmit antenna of the wireless communication system, the third preamble further comprising:

a short training sequence field;

first and second guard interval fields;

a signal field;

first long training sequence field disposed between the first and second guard interval fields; and

second long training sequence field disposed between the second guard interval field and the signal field, wherein the short training sequence field of the fourth preamble has a cyclic shift with respect to the short training sequence field of the third preamble;

wherein the first long training sequence field of the fourth preamble has a cyclic shift with respect to the first long training sequence field of the third preamble;

wherein the second long training sequence field of the fourth preamble has inverted sign with respect to the second long training sequence field of the first preamble;

wherein the second long training sequence field of the fourth preamble has a cyclic shift with respect to the second long training sequence field of the third preamble; and

wherein the signal field of the fourth preamble has a cyclic shift with respect to the signal field of the third preamble.

10. An apparatus comprising:

a processor operative to generate a training sequence comprising at least first and second preambles configured respectively for transmission from at least first and second transmit antennas of a wireless communication system, each of the at least first and second preambles further comprising;

a short training sequence field;

a guard interval field;

a long training sequence field; and

a signal field;

wherein the short training sequence field of the second preamble has a cyclic shift with respect to the short training sequence field of the first preamble;

wherein the long training sequence field of the second preamble has a cyclic shift; and

wherein the signal field of the second preamble has a cyclic shift with respect to the signal of the first preamble.

11. The apparatus of claim 10 wherein only the DC tone of the tones disposed in the long training sequence field of each of the first and second preambles has a zero value.

12. The apparatus of claim 10 wherein the short training sequence field of the second preamble has a cyclic shift of 400 nsec with respect to the short training sequence field of the first preamble, and wherein the long training sequence field of the second preamble has a cyclic shift of 1600 nsec.

13. An apparatus comprising:

a processor operative to generate a training sequence comprising first, second and third preambles configured for transmission from first, second and third transmit antennas of a wireless communication system, each of the first, second and third preambles further comprising;

a short training sequence field having a duration of 8 μ

sec;

a guard interval field having a duration of 1.6 μ

sec;

a long training sequence field having a duration of 6.4 μ

sec; and

a signal field having a duration of 4 μ

sec;

wherein the short training sequence field of the second preamble has a cyclic shift of 200 nsec with respect to the short training sequence field of the first preamble and wherein the short training sequence field of the third preamble has a cyclic shift of 400 nsec with respect to the short training sequence field of the first preamble;

wherein the long training sequence field of the second preamble has a cyclic shift of 1050 nsec with respect to the long training sequence field of the first preamble and wherein the long training sequence field of the third preamble has a cyclic shift of 2100 nsec with respect to the long training sequence field of the first preamble;

wherein the signal field of the second preamble has a cyclic shift of 1050 nsec with respect to the signal field of the first preamble and wherein the signal field of the third preamble has a cyclic shift of 2100 nsec with respect to the signal field of the first preamble;

wherein only the DC tone of the tones disposed in the long training sequence field of each of the first, second, and third preambles has a zero value.

14. An apparatus comprising:

a processor operative to generate a training sequence comprising first, second, third, and fourth preambles configured for transmission from first, second, third and fourth transmit antennas of a wireless communication system, each of the first, second, third, and fourth preambles further comprising;

a short training sequence field having a duration of 8 μ

sec;

a guard interval field having a duration of 1 .6 μ

sec;

a long training sequence field having a duration of 6.4 μ

sec; and

a signal field having a duration of 4 μ

sec;

wherein the short training sequence field of the second preamble has a cyclic shift of 200 nsec with respect to the short training sequence field of the first preamble, wherein the short training sequence field of the third preamble has a cyclic shift of 400 nsec with respect to the short training sequence field of the first preamble, and wherein the short training sequence field of the fourth preamble has a cyclic shift of 600 nsec with respect to the short training sequence field of the first preamble;

wherein the long training sequence field of the second preamble has a cyclic shift of 800 nsec with respect to the long training sequence field of the first preamble, wherein the long training sequence field of the third preamble has a cyclic shift of 1600 nsec with respect to the long training sequence field of the first preamble, and wherein the long training sequence field of the fourth preamble has a cyclic shift of 2400 nsec with respect to the long training sequence field of the first preamble;

wherein the signal field of the second preamble has a cyclic shift of 800 nsec with respect to the signal field of the first preamble, wherein the signal field of the third preamble has a cyclic shift of 1600 nsec with respect to the signal field of the first preamble, and wherein the signal field of the fourth preamble has a cyclic shift of 2400 nsec with respect to the signal field of the first preamble; and

wherein only the DC tone of the tones disposed in the long training sequence field of each of the first, second, third, and fourth preambles has a zero value.

15. An apparatus comprising:

a processor operative to generate a training sequence comprising at least first and second preambles configured respectively for transmission from at least first and second transmit antennas of a wireless communication system, each of the first and second preambles further comprising;

a short training sequence field;

first and second guard interval fields;

a signal field;

first long training sequence field disposed between the first and second guard interval fields; and

second long training sequence field disposed between the second guard interval field and the signal field, wherein the short training sequence field of the second preamble has a cyclic shift with respect to the short training sequence field of the first preamble;

wherein the first long training sequence field of the second preamble has a cyclic shift with respect to the first long training sequence field of the first preamble;

wherein the second long training sequence field of the second preamble has a cyclic shift with respect to the second long training sequence field of the first preamble; and

wherein the signal field of the second preamble has a cyclic shift with respect to the signal field of the first preamble.

16. The apparatus of claim 15 wherein only the DC tone of the tones disposed in the long training sequence field of each of the first and second long training sequence field of each of the first and second preambles has a zero value.

17. The apparatus of claim 16 further comprising a third preamble configured for transmission from a third transmit antenna of the wireless communication system, the third preamble further comprising:

a short training sequence field;

first and second guard interval fields;

a signal field;

first long training sequence field disposed between the first and second guard interval fields; and

second long training sequence field disposed between the second guard interval field and the signal field, wherein the short training sequence field of the third preamble has a cyclic shift with respect to the short training sequence field of the second preamble;

wherein the first long training sequence field of the third preamble has a cyclic shift with respect to the first long training sequence field of the second preamble;

wherein the second long training sequence field of the third preamble has inverted sign with respect to the second long training sequence field of the first preamble;

wherein the second long training sequence field of the third preamble has a cyclic shift with respect to the second long training sequence field of the second preamble; and

wherein the signal field of the third preamble has a cyclic shift with respect to the signal field of the second preamble.

18. The apparatus of claim of claim 17 further comprising a fourth preamble configured for transmission from a fourth transmit antenna of the wireless communication system, the third preamble further comprising:

a short training sequence field;

first and second guard interval fields;

a signal field;

first long training sequence field disposed between the first and second guard interval fields; and

second long training sequence field disposed between the second guard interval field and the signal field,

wherein the short training sequence field of the fourth preamble has a cyclic shift with respect to the short training sequence field of the third preamble;

wherein the first long training sequence field of the fourth preamble has a cyclic shift with respect to the first long training sequence field of the third preamble;

wherein the second long training sequence field of the fourth preamble has inverted sign with respect to the second long training sequence field of the first preamble;

wherein the second long training sequence field of the fourth preamble has a cyclic shift with respect to the second long training sequence field of the third preamble; and

wherein the signal field of the fourth preamble has a cyclic shift with respect to the signal field of the third preamble.

19. A wireless communication device comprising:

a plurality of transmit antennas; and

means for generating a training sequence comprising at least first and second preambles configured respectively for transmission from at least first and second transmit antennas, each of the at least first and second preambles further comprising;

a short training sequence field;

a guard interval field;

a long training sequence field; and

a signal field;

wherein the short training sequence field of the second preamble has a cyclic shift with respect to the short training sequence field of the first preamble;

wherein the long training sequence field of the second preamble has a cyclic shift; and

wherein the signal field of the second preamble has a cyclic shift with respect to the signal of the first preamble.

20. The wireless communication device of claim 19 wherein only the DC tone of the tones disposed in the long training sequence field of each of the first and second preambles has a zero value.

21. The wireless communication device of claim 19 wherein the short training sequence field of the second preamble has a cyclic shift of 400 nsec with respect to the short training sequence field of the first preamble, and wherein the long training sequence field of the second preamble has a cyclic shift of 1600 nsec.

22. A wireless communication device comprising:

a plurality of transmit antennas; and

means for generating a training sequence comprising first, second and third preambles configured for transmission from first, second and third of said transmit antennas, each of the first, second and third preambles further comprising;

a short training sequence field having a duration of 8 μ

sec;

a guard interval field having a duration of 1 .6 μ

sec;

a long training sequence field having a duration of 6.4 μ

sec; and

a signal field having a duration of 4 μ

sec;

wherein the short training sequence field of the second preamble has a cyclic shift of 200 nsec with respect to the short training sequence field of the first preamble and wherein the short training sequence field of the third preamble has a cyclic shift of 400 nsec with respect to the short training sequence field of the first preamble;

wherein the long training sequence field of the second preamble has a cyclic shift of 1050 nsec with respect to the long training sequence field of the first preamble and wherein the long training sequence field of the third preamble has a cyclic shift of 2100 nsec with respect to the long training sequence field of the first preamble;

wherein the signal field of the second preamble has a cyclic shift of 1050 nsec with respect to the signal field of the first preamble and wherein the signal field of the third preamble has a cyclic shift of 2100 nsec with respect to the signal field of the first preamble;

wherein only the DC tone of the tones disposed in the long training sequence field of each of the first, second, and third preambles has a zero value.

23. A wireless communication device comprising:

a plurality of transmit antennas; and

means for generating a training sequence comprising first, second, third, and fourth preambles configured for transmission from first, second, third and fourth of said transmit antennas, each of the first, second, third, and fourth preambles further comprising;

a short training sequence field having a duration of 8 μ

sec;

a guard interval field having a duration of 1 .6 μ

sec;

a long training sequence field having a duration of 6.4 μ

sec; and

a signal field having a duration of 4 μ

sec;

wherein the short training sequence field of the second preamble has a cyclic shift of 200 nsec with respect to the short training sequence field of the first preamble, wherein the short training sequence field of the third preamble has a cyclic shift of 400 nsec with respect to the short training sequence field of the first preamble, and wherein the short training sequence field of the fourth preamble has a cyclic shift of 600 nsec with respect to the short training sequence field of the first preamble;

wherein the long training sequence field of the second preamble has a cyclic shift of 800 nsec with respect to the long training sequence field of the first preamble, wherein the long training sequence field of the third preamble has a cyclic shift of 1600 nsec with respect to the long training sequence field of the first preamble, and wherein the long training sequence field of the fourth preamble has a cyclic shift of 2400 nsec with respect to the long training sequence field of the first preamble;

wherein the signal field of the second preamble has a cyclic shift of 800 nsec with respect to the signal field of the first preamble, wherein the signal field of the third preamble has a cyclic shift of 1600 nsec with respect to the signal field of the first preamble, and wherein the signal field of the fourth preamble has a cyclic shift of 2400 nsec with respect to the signal field of the first preamble; and

wherein only the DC tone of the tones disposed in the long training sequence field of each of the first, second, third, and fourth preambles has a zero value.

24. A wireless communication device comprising:

a plurality of transmit antennas; and

means for generating a training sequence comprising at least first and second preambles configured respectively for transmission from at least first and second if said transmit antennas of a wireless communication system, each of the first and second preambles further comprising;

a short training sequence field;

first and second guard interval fields;

a signal field;

first long training sequence field disposed between the first and second guard interval fields; and

second long training sequence field disposed between the second guard interval field and the signal field, wherein the short training sequence field of the second preamble has a cyclic shift with respect to the short training sequence field of the first preamble;

wherein the first long training sequence field of the second preamble has a cyclic shift with respect to the first long training sequence field of the first preamble;

wherein the second long training sequence field of the second preamble has a cyclic shift with respect to the second long training sequence field of the first preamble; and

wherein the signal field of the second preamble has a cyclic shift with respect to the signal field of the first preamble.

25. The wireless communication device of claim 24 wherein only the DC tone of the tones disposed in the long training sequence field of each of the first and second long training sequence field of each of the first and second preambles has a zero value.

26. The wireless communication device of claim 25 further comprising a third preamble configured for transmission from a third transmit antenna, the third preamble further comprising:

a short training sequence field;

first and second guard interval fields;

a signal field;

first long training sequence field disposed between the first and second guard interval fields; and

second long training sequence field disposed between the second guard interval field and the signal field, wherein the short training sequence field of the third preamble has a cyclic shift with respect to the short training sequence field of the second preamble;

wherein the first long training sequence field of the third preamble has a cyclic shift with respect to the first long training sequence field of the second preamble;

wherein the second long training sequence field of the third preamble has inverted sign with respect to the second long training sequence field of the first preamble;

wherein the second long training sequence field of the third preamble has a cyclic shift with respect to the second long training sequence field of the second preamble; and

wherein the signal field of the third preamble has a cyclic shift with respect to the signal field of the second preamble.

27. The wireless communication device of claim of claim 26 further comprising a fourth preamble configured for transmission from a fourth transmit, the third preamble further comprising:

a short training sequence field;

first and second guard interval fields;

a signal field;

first long training sequence field disposed between the first and second guard interval fields; and

second long training sequence field disposed between the second guard interval field and the signal field,

wherein the short training sequence field of the fourth preamble has a cyclic shift with respect to the short training sequence field of the third preamble;

wherein the first long training sequence field of the fourth preamble has a cyclic shift with respect to the first long training sequence field of the third preamble;

wherein the second long training sequence field of the fourth preamble has inverted sign with respect to the second long training sequence field of the first preamble;

wherein the second long training sequence field of the fourth preamble has a cyclic shift with respect to the second long training sequence field of the third preamble; and

wherein the signal field of the fourth preamble has a cyclic shift with respect to the signal field of the third preamble.