High data rate wireless bridging

• US 7,352,688 B1
• Filed: 12/31/2002
• Issued: 04/01/2008
• Est. Priority Date: 12/31/2002
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Pignatelli, David, Douglas, Bretton, Perahia, Eldad
• Primary Examiner(s): VU, THONG H
• Application Number:
  US10/335,500
• Time in Patent Office: 1,918 Days
• Field of Search: 370/208, 370/338, 370/210, 370/461, 375/219, 375/132, 375/267, 455/12, 455/67, 455/63
• US Class Current: 370/206
• CPC Class Codes: H04B 7/0413 MIMO systems
• CPC Class Codes: H04B 7/10 Polarisation diversity; Directional diversity
• CPC Class Codes: H04L 25/0202 Channel estimation
• CPC Class Codes: H04L 25/0226 sounding signals per se
• CPC Class Codes: H04L 27/2655 Synchronisation arrangements
• CPC Class Codes: H04L 5/0023 Time-frequency-space
• CPC Class Codes: H04L 5/0048 Allocation of pilot signals, i.e. of signals known to the receiver

Abstract

A specialized preamble is provided to facilitate matrix channel estimation of a MIMO channel. In a particular implementation, a channel training preamble provided by the IEEE 802.11a standard is modified to facilitate MIMO channel estimation.

Claims

1. In a wireless communication system, a method for transmitting a signal, said method comprising:

transmitting a first OFDM signal via a first antenna element representing a horizontal polarization of an antenna;

transmitting a second OFDM signal via a second antenna element representing a vertical polarization of said antenna;

transmitting channel training information in said first OFDM signal while inhibiting transmission of said second OFDM signal during a first channel training period; and

transmitting channel training information in said second OFDM signal while inhibiting transmission of said first OFDM signal in a second channel training period;

wherein said channel training information is configured for use by a receiver in determining a MIMO channel response.

2. The method of claim 1 wherein said channel training information is defined by the IEEE 802.11a standard.

3. In a wireless communication system, a method for transmitting a signal, said method comprising:

transmitting a first OFDM signal via a first antenna element representing a horizontal polarization of an antenna;

transmitting a second OFDM signal via a second antenna element representing a vertical polarization of said antenna; and

during a channel training period, transmitting channel training information simultaneously in a first set of subcarriers of said first OFDM signal and in a second set of subcarriers of the second OFDM signal, said first set of subcarriers and said second set of subcarriers being non-overlapping;

wherein said channel training information is configured for use by a receiver in determining a MIMO channel response.

4. The method of claim 3 wherein said channel training information is defined by the IEEE 802.11a standard.

5. The method of claim 3 wherein said first set of subcarriers and said second set of subcarriers alternate in order of frequency.

6. In a wireless communication system, apparatus for transmitting a signal, said apparatus comprising:

a first transmitter block that transmits a first OFDM signal via a first antenna element representing a horizontal polarization of an antenna;

a second transmitter block that transmits a second OFDM signal via a second antenna element representing a vertical polarization of said antenna;

a first channel training information insertion block that inserts channel training information in said first OFDM signal while transmission of said second OFDM signal is inhibited; and

a second channel training information insertion block that inserts channel training information in said second OFDM signal while transmission of said first OFDM signal is inhibited;

wherein said channel training information is configured for use by a receiver in determining a MIMO channel response.

7. The apparatus of claim 6 wherein said channel training information is defined by the IEEE 802.11a standard.

8. In a wireless communication system, apparatus for transmitting a signal, said apparatus comprising:

a first transmitter block that transmits a first OFDM signal via a first antenna element representing a horizontal polarization of an antenna;

a second transmitter block that transmits a second OFDM signal via a second antenna element representing a vertical polarization of said antenna;

a channel training information insertion system that during a channel training period, transmits channel training information simultaneously in a first set of subcarriers of said first OFDM signal and in a second set of subcarriers of the second OFDM signal, said first set of subcarriers and said second set of subcarriers being non-overlapping;

wherein said channel training information is configured for use by a receiver in determining a MIMO channel response.

9. The apparatus of claim 8 wherein said channel training information is defined by the IEEE 802.11a standard.

10. The apparatus of claim 8 wherein said first set of subcarriers and said second set of subcarriers alternate in order of frequency.

11. In a wireless communication system, apparatus for transmitting a signal, said apparatus comprising:

means for transmitting a first OFDM signal via a first antenna element representing a horizontal polarization of an antenna;

means for transmitting a second OFDM signal via a second antenna element representing a vertical polarization of said antenna;

means for transmitting channel training information in said first OFDM signal while inhibiting transmission of said second OFDM signal; and

means for transmitting channel training information in said second OFDM signal while inhibiting transmission of said first OFDM signal;

wherein said channel training information is configured for use by a receiver in determining a MIMO channel response.

12. In a wireless communication system, apparatus for transmitting a signal, said apparatus comprising:

means for transmitting a first OFDM signal via a first antenna element representing a horizontal polarization of an antenna;

means for transmitting a second OFDM signal via a second antenna element representing a vertical polarization of said antenna; and

means for, during a channel training period, transmitting channel training information simultaneously in a first set of subcarriers of said first OFDM signal and in a second set of subcarriers of the second OFDM signal, said first set of subcarriers and said second set of subcarriers being non-overlapping

wherein said channel training information is configured for use by a receiver in determining a MIMO channel response.