Method and apparatus for improved antenna isolation for per-antenna training using variable scaling

• US 7,742,770 B2
• Filed: 03/24/2006
• Issued: 06/22/2010
• Est. Priority Date: 03/24/2006
• Status: Expired due to Fees

• Current Assignee: Avago Technologies General IP PTE Limited (Broadcom, Inc.)
• Original Assignee: Agere Systems Incorporated (Broadcom, Inc.)
• Inventors: Campbell, Edward E., Mujtaba, Syed A.
• Primary Examiner(s): Le; Lana N
• Assistant Examiner(s): Hsieh; Ping Y
• Application Number:
  US11/388,294
• Publication Number:
  US 20070224946A1
• Time in Patent Office: 1,551 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, 455/450, 375/260, 375/267
• US Class Current: 455/450
• CPC Class Codes: H04B 7/04 using two or more spaced independent antennas
• CPC Class Codes: H04B 7/0602 using antenna switching H04B7/0686 takes precedence; antenna beam directivity switching H01Q3/24
• 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: H04L 25/022 of frequency response
• CPC Class Codes: H04L 25/0224 using sounding 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 transmits the long training sequence with an increased power level relative to a transmission of a payload by the active transmit antenna branch. The increased power level for the active transmit antenna branch compensates for the inactive transmit antenna branches being silent during the given time. Thus, the active transmit antenna branch provides approximately the same antenna power while transmitting the long training sequence as a total power of the plurality of transmit antenna branches during a transmission of the payload. The increased power level can be provided, for example, by a digital-to-analog converter associated with the active transmit antenna branch.

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, wherein said active transmit antenna branch transmits said long training sequence with an increased power level relative to a transmission of a payload by said active transmit antenna branch.

2. The method of claim 1, wherein said increased power level for said active transmit antenna branch compensates for said inactive transmit antenna branches being silent during said given time.

3. The method of claim 1, wherein said active transmit antenna branch provides approximately the same antenna power while transmitting said long training sequence as a total power of said plurality of transmit antenna branches during a transmission of said payload.

4. The method of claim 1, wherein said increased power level is provided by a digital-to-analog converter associated with said active transmit antenna branch.

5. 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.

6. 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.

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

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, wherein said active transmit antenna branch transmits said long training sequence with an increased power level relative to a transmission of a payload by said active transmit antenna branch.

9. The transmitter of claim 8, wherein said increased power level for said active transmit antenna branch compensates for said inactive transmit antenna branches being silent during said given time.

10. The transmitter of claim 8, wherein said active transmit antenna branch provides approximately the same antenna power while transmitting said long training sequence as a total power of said plurality of transmit antenna branches during a transmission of said payload.

11. The transmitter of claim 8, wherein said increased power level is provided by a digital-to-analog converter associated with said active transmit antenna branch.

12. 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.

13. 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.

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

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, wherein said long training sequence is transmitted by said active transmit antenna branch with an increased power level relative to a transmission of a payload by said active transmit antenna branch.

16. The digital signal processor of claim 15, wherein said increased power level for said active transmit antenna branch compensates for said inactive transmit antenna branches being silent during said given time.

17. The digital signal processor of claim 15, wherein said active transmit antenna branch provides approximately the same antenna power while transmitting said long training sequence as a total power of said plurality of transmit antenna branches during a transmission of said payload.

18. The digital signal processor of claim 15, wherein said increased power level is provided by a digital-to-analog converter associated with said active transmit antenna branch.

19. 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.

20. 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.