Method and system for antenna interference cancellation

• US 20050226353A1
• Filed: 11/17/2004
• Published: 10/13/2005
• Est. Priority Date: 11/17/2003
• Status: Active Grant

• Current Assignee: Intersil Americas LLC (Renesas Electronics Corporation)
• Original Assignee: Quellan, Inc. (Renesas Electronics Corporation)
• Inventors: Laskar, Joy, Kim, Andrew Joo, Tentzeris, Emmanouil M., Gebara, Edward
• Granted Patent: US 7,123,676 B2
• Time in Patent Office: Days
• US Class Current: 375/346
• CPC Class Codes: H01Q 1/521 reducing the coupling between adjacent antennas
• CPC Class Codes: H01Q 1/525 between emitting and receiving antennas
• CPC Class Codes: H04B 1/1027 assessing signal quality or detecting noise/interference for the received signal
• CPC Class Codes: H04B 1/1036 with automatic suppression of narrow band noise or interference, e.g. by using tuneable notch filters H04B1/123 takes precedence; filter circuits H03H
• CPC Class Codes: H04B 1/126 having multiple inputs, e.g. auxiliary antenna for receiving interfering signal aerials in general H01Q
• CPC Class Codes: H04B 1/525 with means for reducing leakage of transmitter signal into the receiver
• CPC Class Codes: H04B 7/15585 by interference cancellation
• CPC Class Codes: H04L 1/24 Testing correct operation
• CPC Class Codes: H04L 7/00 Arrangements for synchronising receiver with transmitter synchronisation of generators of electric oscillations or pulses H03L7/00

Abstract

A wireless communication system can comprise two or more antennas that interfere with one another via free space coupling, surface wave crosstalk, dielectric leakage, or other interference effect. The interference effect can produce an interference signal on one of the antennas. A cancellation device can suppress antenna interference by generating an estimate of the interference signal and subtracting the estimate from the interference signal. The cancellation device can generate the estimate based on sampling signals on an antenna that generates the interference or on an antenna that receives the interference. The cancellation device can comprise a model of the crosstalk effect. Transmitting test signals on the communication system can define or refine the model.

Claims

1. A method for suppressing an interference signal imposed by a first antenna on a second antenna, comprising:

sampling a transmitted signal on the first antenna;

processing the sampled signal according to a parameter to generate an estimate of the interference signal;

applying the estimate of the interference signal to the second antenna to suppress the interference signal; and

varying the parameter in response to monitoring the suppressed interference signal.

2. The method of claim 1, wherein:

the interference signal has a first phase;

the estimate of the interference signal has a second phase;

the parameter comprises a phase shift;

processing the sampled signal comprises applying the phase shift to the sampled signal; and

the varying step comprises adjusting the phase shift to match the second phase to the first phase.

3. The method of claim 1, wherein processing the sampled signal comprises filtering the sampled signal with a filter having a frequency response, and wherein varying the parameter comprises adjusting the frequency response.

4. The method of claim 1, wherein the estimate of the interference signal comprises a cancellation signal.

5. The method of claim 1, wherein:

the processing step comprises;

applying a phase shift to the sampled signal;

filtering the sampled signal according to a filter parameter;

delaying the sampled signal by a time; and

amplifying the sampled signal according to a gain; and

varying the parameter comprises adjusting the phase shift, the filter parameter, the time, and the gain.

6. The method of claim 1, wherein the transmitted signal comprises a test signal and a communication signal.

7. The method of claim 1, further comprising the step of transmitting, on the first antenna a first test signal having a first frequency, a second test signal having a second frequency, and a communication signal having a third frequency, wherein the third frequency is between the first frequency and the second frequency, and wherein

the sampling step comprises sampling the first transmitted test signal and sampling the second transmitted test signal.

8. The method of claim 1, wherein the interference signal is imposed by the first antenna on the second antenna via an interference effect and wherein the method further comprises the steps of:

generating a pilot signal;

applying the pilot signal to the first antenna;

transferring at least a portion of the pilot signal from the first antenna to the second antenna via the interference effect; and

specifying a model of the interference effect based on monitoring the transferred portion of the pilot signal, wherein

the transmitted signal comprises a communication signal, and

processing the sampled signal comprises applying the specified model to the communication signal.

9. The method of claim 1, wherein monitoring the suppressed interference signal comprises tapping power from a feed line of the second antenna and measuring the tapped power.

10. A method for reducing interference on an antenna system, comprising:

transmitting a test signal on a first antenna;

coupling a portion of the test signal from the first antenna to a second antenna via an interference effect;

defining a model of the interference effect based on processing the test signal;

responsive to transmitting a communication signal on the first antenna, coupling the interference onto the second antenna via the interference effect;

outputting an estimate of the interference in response to processing the communication signal with the model; and

applying the estimate to the second antenna to reduce the interference.

11. The method of claim 10, wherein processing the test signal comprises monitoring the portion of the test signal coupled to the second antenna.

12. The method of claim 10, wherein the interference effect comprises free space coupling.

13. The method of claim 10, wherein the interference effect comprises dielectric leakage.

14. The method of claim 10, wherein the interference effect comprises surface wave coupling.

15. The method of claim 10, wherein transmitting the test signal on the first antenna comprises feeding the test signal onto a feed line of the first antenna via a first coupler and wherein applying the estimate to the second antenna comprises feeding the test signal onto a feed line of the second antenna via a second coupler.

16. The method of claim 10, wherein applying the estimate to the second antenna comprises subtracting the estimate from the interference and the portion of the test signal coupled to the second antenna via the crosstalk effect.

17. The method of claim 10, wherein the model comprises a filter and wherein defining the model comprises adjusting the filter.

18. A system, for canceling a signal coupled onto a dormant antenna by an active antenna, comprising:

a first coupler, comprising a port that connects to a feed line of the dormant antenna, for feeding a sample of the signal to a signal processing circuit; and

a second coupler comprising a port for feeding a cancellation signal to the feed line, wherein the signal processing circuit generates the sampled signal based on amplifying and shifting the sampled signal.

19. The system of claim 18, wherein:

amplifying the sampled signal comprises applying a gain to the sampled signal;

shifting the sampled signal comprises applying a phase shift to the sampled signal; and

the system further comprises;

a third coupler for obtaining a feedback signal from the feed line; and

a controller for adjusting the gain and the phase shift based on the feedback signal.

20. The system of claim 18, wherein the first coupler comprises a splitter and the second coupler comprises a summation node.