Method and apparatus for preamble training in a multiple antenna communication system

• US 8,619,907 B2
• Filed: 01/24/2005
• Issued: 12/31/2013
• Est. Priority Date: 06/10/2004
• Status: Active Grant

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Agere Systems LLC (Broadcom, Inc.)
• Inventors: Mujtaba, Syed Aon, Wang, Xiaowen
• Primary Examiner(s): Vlahos, Sophia
• Application Number:
  US11/043,025
• Publication Number:
  US 20050276347A1
• Time in Patent Office: 3,263 Days
• Field of Search: 375/260, 375/267, 375/299, 375/316, 375/340, 375/346, 375/347, 375/349, 455/101, 455/132, 455/296, 455/103, 370/334, 370/310, 370/505, 370/338, 370203-208
• US Class Current: 375/299
• CPC Class Codes: H04B 7/0667 of delayed versions of same signal using space-time coding H04L1/0618
• CPC Class Codes: H04B 7/0684 using different training sequences per antenna

Abstract

Methods and apparatus are provided for communicating data in a multiple antenna communication system having N transmit antennas. According to one aspect of the invention, a header format includes a legacy preamble having at least one legacy long training field and an extended portion having at least N additional long training fields on each of the N transmit antennas. The N additional long training fields may be tone interleaved across the N transmit antennas and are used for MIMO channel estimation. The extended portion may include a short training field for power estimation. The short training field may be tone interleaved across the N transmit antennas and have an extended duration to support beam steering.

Claims

1. A method for transmitting data in a multiple antenna communication system having N transmit antennas, said method comprising the steps of:

obtaining a signal comprising a legacy preamble having at least one legacy long training field and at least one legacy short training field and an extended portion having in the range of one to N−

1 additional long training fields on each of said N transmit antennas and at least one additional short training field, wherein each additional long training field contains one long OFDM symbol and N is greater than two, wherein said long OFDM symbol utilizes a frequency grid of M points and wherein a data OFDM symbol utilizes a frequency grid of M/2 points, and transmitting said signal.

2. The method of claim 1, wherein said legacy preamble further comprises one SIGNAL field.

3. The method of claim 1, wherein said legacy preamble is an 802.11 a/g preamble.

4. The method of claim 1, wherein said additional long training fields are tone interleaved across said N transmit antennas.

5. The method of claim 4, wherein N equals three and a first additional long training field uses a first set of tones on a first transmit antenna, a second set of tones on a second transmit antenna, and a third set of tones on a third transmit antenna.

6. The method of claim 1, wherein only said additional long training fields are used for MIMO channel estimation.

7. The method of claim 1, wherein said extended portion further includes said additional short training field for power estimation.

8. The method of claim 7, wherein said additional short training field is tone interleaved across said N transmit antennas.

9. The method of claim 7, wherein said additional short training field has an extended duration to support beam steering.

10. The method of claim 1, wherein said extended portion further includes a signal field identifying a preamble format.

11. A transmitter in a multiple antenna communication system, comprising:

N transmit antennas configured to transmit a signal obtained by a transmitter circuit, the signal comprising a legacy preamble having at least one legacy long training field and at least one legacy short training field and an extended portion having in the range of one to N−

1 additional long training fields on each of said N transmit antennas and at least one additional short training field, wherein each additional long training field contains one long OFDM symbol and N is greater than two, wherein said long OFDM symbol utilizes a frequency grid of M points and wherein a data OFDM symbol utilizes a frequency grid of M/2 points.

12. The transmitter of claim 11, wherein said legacy preamble further comprises one SIGNAL field.

13. The transmitter of claim 11, wherein said additional long training fields are tone interleaved across said N transmit antennas.

14. The transmitter of claim 13, wherein N equals three and a first additional long training field uses a first set of tones on a first transmit antenna, a second set of tones on a second transmit antenna, and a third set of tones on a third transmit antenna.

15. The transmitter of claim 11, wherein only said additional long training fields are used for MIMO channel estimation.

16. The transmitter of claim 11, wherein said extended portion further includes said additional short training field for power estimation and a signal field identifying a preamble format.

17. A method for receiving data on at least one receive antenna transmitted by a transmitter having N transmit antennas in a multiple antenna communication system, said method comprising the steps of:

receiving a signal comprising a legacy preamble having at least one legacy long training field and at least one legacy short training field and an extended portion having in the range of one to N−

1 additional long training fields on each of said N transmit antennas and at least one additional short training field, wherein each additional long training field contains one long OFDM symbol and N is greater than two, wherein said long OFDM symbol utilizes a frequency grid of M points and wherein a data OFDM symbol utilizes a frequency grid of M/2 points, and processing said signal.

18. The method of claim 17, wherein said additional long training fields are tone interleaved across said N transmit antennas.

19. The method of claim 17, wherein only said additional long training fields are used for MIMO channel estimation.

20. The method of claim 17, wherein said extended portion further includes said additional short training field for power estimation and a signal field identifying a preamble format.

21. A receiver in a multiple antenna communication system having at least one transmitter having N transmit antennas, comprising:

at least one receive antenna configured to receive a signal comprising a legacy preamble having at least one legacy long training field and at least one legacy short training field and an extended portion having in the range of one to N−

1 additional long training fields on each of said N transmit antennas and at least one additional short training field, wherein each additional long training field contains one long OFDM symbol and N is greater than two, wherein said long OFDM symbol utilizes a frequency grid of M points and wherein a data OFDM symbol utilizes a frequency grid of M/2 points, and a receiver circuit configured to process the received signal.

22. The receiver of claim 21, wherein said additional long training fields are tone interleaved across said N transmit antennas.

23. The receiver of claim 21, wherein only said additional long training fields are used for MIMO channel estimation.

24. The receiver of claim 21, wherein said extended portion further includes said additional short training field for power estimation and a signal field identifying a preamble format.