Multiple interferer cancellation for communications systems

• US 9,350,398 B2
• Filed: 05/21/2013
• Issued: 05/24/2016
• Est. Priority Date: 05/21/2012
• Status: Active Grant

• Current Assignee: Bascom Hunter Technologies, Inc., L3 Technologies, Inc. (L3Harris Technologies, Inc.)
• Original Assignee: L-3 Communications Corporation (L3Harris Technologies, Inc.)
• Inventors: Kpodzo, Elias Bonaventure, Holland, Robert, Deng, Yanhua, Dourbal, Paul
• Primary Examiner(s): Leung, Danny
• Application Number:
  US13/899,505
• Publication Number:
  US 20130308940A1
• Time in Patent Office: 1,099 Days
• Field of Search: 398/39
• US Class Current: 1/1
• CPC Class Codes: H04B 1/10 Means associated with receiver for limiting or suppressing noise or interference
• CPC Class Codes: H04B 1/1027 assessing signal quality or detecting noise/interference for the received signal
• CPC Class Codes: H04B 1/109 by improving strong signal performance of the receiver when strong unwanted signals are present at the receiver input
• CPC Class Codes: H04B 10/00 Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
• CPC Class Codes: H04B 10/07955 Monitoring or measuring power
• CPC Class Codes: H04B 10/2507 for the reduction or elimination of distortion or dispersion
• CPC Class Codes: H04B 10/2575 Radio-over-fibre, e.g. radio frequency signal modulated onto an optical carrier
• CPC Class Codes: H04B 17/318 Received signal strength
• CPC Class Codes: H04B 17/336 Signal-to-interference ratio [SIR] or carrier-to-interference ratio [CIR]
• CPC Class Codes: H04B 2210/006 Devices for generating or processing an RF signal by optical means
• CPC Class Codes: H04K 3/20 Countermeasures against jamming in radar G01S7/36; interference suppression in receivers H04B1/10
• CPC Class Codes: H04K 3/228 Elimination in the received signal of jamming or of data corrupted by jamming interference suppression in receivers H04B1/10
• CPC Class Codes: H04L 43/16 Threshold monitoring

Abstract

An interference cancellation system (ICS) may be used with a communication system to prevent or minimize interference from one or more sources. The ICS may receive radio RF signals comprised of one or more signals of interest (SOI) and multiple interfering signals. The ICS may use a sample of the interfering signals to cancel the interfering signals from the SOI. The multiple interfering signals may be converted into a single optical signal for cancellation. One or more optical cancellation paths may be used for interference cancellation. Each optical cancellation path may include an optical attenuator and/or an optical delay to achieve phase shifts and/or delays for interference cancellation.

Claims

1. An interference cancellation system (ICS) comprising:

radio frequency (RF) circuitry configured to receive a plurality of RF interference signals and a combined signal, the plurality of RF interference signals comprising a first RF interference signal and a second RF interference signal, and the combined signal comprising a combination of a signal of interest (SOI) and at least the plurality of RF interference signals;

optical circuitry configured to;

convert the first RF interference signal to a first optical interference signal and apply a 180 phase shift to the first optical interference signal,

convert the second RF interference signal to a second optical interference signal and apply a 180 phase shift to the second optical interference signal,

convert the combined signal to an optical combined signal, wherein the optical circuitry comprises a first optical cancellation path and a second optical cancellation path, each of the first and second optical cancellation paths comprise an optical attenuator and an optical time delay, the first optical cancellation path is configured to attenuate and apply a time delay the first optical interference signal, and the second optical cancellation path is configured to attenuate and apply time delay the second optical interference signal, and

combine the first optical interference signal after processing by the first optical cancellation path and the second optical interference signal after processing by the second optical cancellation path with the optical combined signal to generate an optical output signal, and

convert the optical output signal to an RF output signal, the RF output signal comprising the SOI with the first and second RF interference signals substantially removed; and

a processor configured to control the attenuation and time delays applied via the first and second optical cancellation paths of the optical circuitry.

2. The ICS as in claim 1, wherein the plurality of RF interference signals further comprise a third RF interference signal, and the optical circuitry comprises a third optical cancellation path for processing the third RF interference signal after the third RF interference signal is converted to a third optical interference signal.

3. The ICS as in claim 2, wherein the plurality of RF interference signals further comprise a fourth RF interference signal, and the optical circuitry is configured to jointly process the third and fourth RF interference signals using the third optical cancellation path after the third and fourth RF interference signals are converted to a third and fourth optical interference signals.

4. The ICS as in claim 1, wherein the optical circuitry comprises at least one laser modulator that is configured to convert the first RF interference signal to the first optical interference signal, convert the second RF interference signal to the second optical interference signal, and convert the combined signal to the optical combined signal.

5. The ICS as in claim 4, wherein the processor is configured to control the optical circuitry based at least on part a received signal strength indication (RSSI) associated with the RF output signal.

6. The ICS as in claim 1, wherein the processor is configured to determine when a signal strength of the first RF interference signal exceeds a threshold, and control the optical circuitry to process the first interference signal using the first optical cancellation path based on the signal strength of the first interference signal exceeding the threshold.

7. The ICS as in claim 6, wherein the processor is configured to determine when a signal strength of the second RF interference signal exceeds a second threshold, and control the optical circuitry to process the second optical interference signal using the second optical cancellation path based on the signal strength of the second RF interference signal exceeding the threshold.

8. The ICS as in claim 7, wherein the processor is configured to deactivate the second optical cancellation path during time periods when the signal strength of the second interference signal is below the second threshold.

9. The ICS as in claim 1, wherein at least one of the first interference signal or the second interference signal is a remote signal estimated at the ICS.

10. The ICS as in claim 1, wherein the processor is configured to activate and deactivate each of the first and second optical cancellation paths based on the presence or absence of the first or second interference signals.

15. The ICS as in claim 4, wherein the processor is configured to control the optical circuitry based at least on part a received signal strength indication (RSSI) associated with the RF output signal.

17. The ICS as in claim 6, wherein the RF interference signals being substantially removed corresponds to a cancellation attenuation of each of the RF interference signals to a level associated approximately at background noise.

18. The ICS as in claim 1, wherein at least one of the first interference signal or the second interference signal is a remote signal estimated at the ICS.

19. The ICS as in claim 1, wherein the processor is configured to activate and deactivate at least one of the first and second optical cancellation paths based on the presence or absence of the first or second interference signals.

11. An interference cancellation system (ICS) comprising a processor configured to:

control radio frequency (RF) circuitry, wherein the RF circuitry is configured to process a plurality of RF interference signals and a combined signal, the plurality of RF interference signals comprising a first RF interference signal and a second RF interference signal, and the combined signal comprising a combination of a signal of interest (SOI) and at least the plurality of RF interference signals; and

control optical circuitry that is configured to;

convert the first RF interference signal to a first optical interference signal and apply a 180 phase shift to the first optical interference signal,

convert the second RF interference signal to a second optical interference signal and apply a 180 phase shift to the second optical interference signal,

convert the combined signal to an optical combined signal, wherein the optical circuitry comprises a first optical cancellation path and a second optical cancellation path, each of the first and second optical cancellation paths comprise an optical attenuator and an optical time delay, the first optical cancellation path is configured to attenuate and apply a time delay the first optical interference signal, and the second optical cancellation path is configured to attenuate and apply time delay the second optical interference signal,

combine the first optical interference signal after processing by the first optical cancellation path and the second optical interference signal after processing by the second optical cancellation path with the optical combined signal to generate an optical output signal, and

convert the optical output signal to an RF output signal, the RF output signal comprising the SOI with the first and second RF interference signals substantially removed.

12. The ICS as in claim 11, wherein the plurality of RF interference signals further comprise a third RF interference signal, and the optical circuitry comprises a third optical cancellation path for processing the third RF interference signal after the third RF interference signal is converted to a third optical interference signal.

13. The ICS as in claim 12, wherein the plurality of RF interference signals further comprise a fourth RF interference signal, and the optical circuitry is configured to jointly process the third and fourth RF interference signals using the third optical cancellation path after the third and fourth RF interference signals are converted to a third and fourth optical interference signal.

14. The ICS as in claim 11, wherein the optical circuitry comprises at least one photodiode that is configured to convert the optical output signal to the RF output signal.

16. The ICS as in claim 11, wherein the RF interference signals being substantially removed corresponds to a cancellation attenuation of each of the RF interference signals of approximately 40 dB or greater.

20. An interference cancellation method comprising:

radio frequency (RF) receiving a plurality of RF interference signals and a combined signal, the plurality of RF interference signals comprising a first RF interference signal and a second RF interference signal, and the combined signal comprising a combination of a signal of interest (SOI) and at least the plurality of RF interference signals;

optical circuitry converting the first RF interference signal to a first optical interference signal and applying a 180 phase shift to the first optical interference signal;

the optical circuitry converting the second RF interference signal to a second optical interference signal and applying a 180 phase shift to the second optical interference signal;

the optical circuitry converting the combined signal to an optical combined signal, wherein the optical circuitry comprises a first optical cancellation path and a second optical cancellation path, each of the first and second optical cancellation paths comprise an optical attenuator and an optical time delay, the first optical cancellation path is used to attenuate and apply a time delay the first optical interference signal, and the second optical cancellation path is used to attenuate and apply time delay the second optical interference signal;

the optical circuitry combining the first optical interference signal after processing by the first optical cancellation path and the second optical interference signal after processing by the second optical cancellation path with the optical combined signal to generate an optical output signal; and

the optical circuitry converting the optical output signal to an RF output signal, the RF output signal comprising the SOI with the first and second RF interference signals substantially removed.