Method and apparatus for improved antenna isolation for per-antenna training using transmit/receive switch

• US 8,694,030 B2
• Filed: 03/24/2006
• Issued: 04/08/2014
• Est. Priority Date: 03/24/2006
• Status: Active Grant

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Agere Systems Incorporated (Broadcom, Inc.)
• Inventors: Campbell, Edward E., Mujtaba, Syed A.
• Primary Examiner(s): HSIEH, PING Y
• Application Number:
  US11/388,330
• Publication Number:
  US 20070224947A1
• Time in Patent Office: 2,937 Days
• Field of Search: 455/502, 455/66.1, 455/101, 455/103, 455/458, 455/82, 455/83, 455/84, 455/88, 455/78, 455/63.1, 455/67.11
• US Class Current: 455/458
• CPC Class Codes: H04B 7/04 using two or more spaced independent antennas
• CPC Class Codes: H04B 7/0615 of weighted versions of same signal
• CPC Class Codes: H04B 7/0684 using different training sequences per antenna
• CPC Class Codes: H04B 7/08 at the receiving station
• CPC Class Codes: H04L 25/0204 of multiple channels
• CPC Class Codes: H04L 25/0224 using sounding signals
• CPC Class Codes: H04L 27/261 Details of reference signals

Abstract

Methods and apparatus are provided for per-antenna training in a multiple antenna communication system having a plurality of transmit antenna branches. A long training sequence is transmitted on each of the transmit antenna branches such that only one of the transmit antenna branches is active at a given time. The active transmit antenna branch is configured in a transmit mode during the given time and one or more of the inactive transmit antenna branches are configured in a receive mode during the given time. The transmit and receive modes are configured, for example, by applying a control signal to one or more switches.

Claims

1. A method for per-antenna training in a multiple antenna communication system having a plurality of transmit antenna branches, said method comprising the step of:

transmitting a long training sequence on each of said transmit antenna branches such that only one of said transmit antenna branches is active at a given time;

configuring said active transmit antenna branch in a transmit mode during said given time; and

configuring one or more of said inactive transmit antenna branches in a receive mode during said given time.

2. The method of claim 1, further comprising the step of applying a digital code corresponding to a binary value of zero to one or more digital-to-analog converters associated with said inactive transmit antenna branches.

3. The method of claim 1, further comprising the step of applying a digital code associated with said long training sequence to one or more digital-to-analog converters associated with said active transmit antenna branch.

4. The method of claim 1, wherein each of said inactive transmit antenna branches has a power level below a predefined threshold.

5. The method of claim 1, wherein said transmit and receive modes are configured by applying a control signal to one or more switches.

6. The method of claim 1, further comprising the step of transmitting a short training sequence substantially simultaneously on each of said transmit antennas.

7. The method of claim 1, wherein said long training sequences are used for MIMO channel estimation.

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

a plurality of transmit antenna branches for transmitting a long training sequence such that only one of said transmit antenna branches is active at a given time; and

a transmit/receive switch associated with each of said plurality of transmit antenna branches, whereby said active transmit antenna branch is configured in a transmit mode during said given time and one or more of said inactive transmit antenna branches are configured in a receive mode during said given time.

9. The transmitter of claim 8, further comprising a digital signal processor for applying a digital code corresponding to a binary value of zero to one or more digital-to-analog converters associated with said inactive transmit antenna branches.

10. The transmitter of claim 8, further comprising a digital signal processor for applying a digital code associated with said long training sequence to one or more digital-to-analog converters associated with said active transmit antenna branch.

11. The transmitter of claim 8, wherein each of said inactive transmit antenna branches has a power level below a predefined threshold.

12. The transmitter of claim 8, wherein said transmit and receive modes are configured by applying a control signal to said transmit/receive switches.

13. The transmitter of claim 8, wherein said plurality of transmit antenna branches transmit a short training sequence substantially simultaneously on each of said transmit antennas.

14. The transmitter of claim 8, wherein said long training sequences are used for MIMO channel estimation.

15. A digital signal processor for a multiple antenna communication system, comprising:

a memory; and

at least one processor, coupled to the memory, operative to;

generate a long training sequence for transmission on a plurality of transmit antenna branches such that only one of said transmit antenna branches is active at a given time; and

generate a control signal for a transmit/receive switch associated with each of said plurality of transmit antenna branches, whereby said active transmit antenna branch is configured in a transmit mode during said given time and one or more of said inactive transmit antenna branches are configured in a receive mode during said given time.

16. The digital signal processor of claim 15, wherein said processor is further operative to apply a digital code corresponding to a binary value of zero to one or more digital-to-analog converters associated with said inactive transmit antenna branches.

17. The digital signal processor of claim 15, wherein said processor is further operative to apply a digital code associated with said long training sequence to one or more digital-to-analog converters associated with said active transmit antenna branch.

18. The digital signal processor of claim 15, wherein each of said inactive transmit antenna branches has a power level below a predefined threshold.

19. The digital signal processor of claim 15, wherein said processor is further operative to generate a short training sequence for substantially simultaneous transmission by said plurality of transmit antenna branches.

20. The digital signal processor of claim 15, wherein said long training sequences are used for MIMO channel estimation.