Systems and methods for active interference cancellation to improve coexistence

• US 9,210,535 B2
• Filed: 10/04/2012
• Issued: 12/08/2015
• Est. Priority Date: 10/04/2012
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Abdollahi-Alibeik, Shahram, Nathawad, Lalitkumar, Kheirkhahi, Alireza, Gong, Ke, Agah, Ali
• Primary Examiner(s): LE, THANH C
• Application Number:
  US13/645,346
• Publication Number:
  US 20140099893A1
• Time in Patent Office: 1,160 Days
• Field of Search: 455/41.1, 455/63.1, 455/278.1, 455/279.1, 455/296, 455/302, 455/304, 455/305, 455/307, 455/130, 333/138, 333/172
• US Class Current: 1/1
• CPC Class Codes: H04B 1/525 with means for reducing leakage of transmitter signal into the receiver
• CPC Class Codes: H04J 11/0023 Interference mitigation or co-ordination direct sequence spread spectrum [DSSS] systems H04B1/7097; frequency hopping H04B1/713; allocation criteria for ingress interference avoidance H04L5/0062; frequency allocation criteria for requirements on out-of-channel emissions H04L5/0066; arrangements for removing intersymbol interference or baseband equalisers H04L25/03006; peak power aspects in multicarrier modulation H04L27/2614; power management H04W52/00; traffic scheduling H04W72/54, H04W72/541
• CPC Class Codes: H04W 4/80 Services using short range communication, e.g. near-field communication [NFC], radio-frequency identification [RFID] or low energy communication

Abstract

This disclosure describes techniques for providing active interference cancellation in a wireless communication system having a Bluetooth transmit chain and a WLAN receive chain. A signal sampled from the Bluetooth transmit chain is gain and phase adjusted to offset interference in the WLAN receive chain. A quadrature phase shifter may be used to generate quadrature components of the sampled signal that are selectively combined to achieve a desired phase adjustment. The phase shifter may be stabilized by a variable capacitor. These techniques may be extended to MIMO systems.

Claims

1. A method for providing active interference cancellation between a Bluetooth transmit chain and a wireless local area network (WLAN) receive chain, comprising sampling a signal from the Bluetooth transmit chain, generating a plurality of quadrature components of the sampled signal with a polyphase filter quadrature radio-frequency (RF) phase shifter, and adjusting a phase of the sampled signal by weighting and combining the plurality of quadrature components in response to digital baseband feedback to create an output signal.

2. The method of claim 1, further comprising controlling an absolute phase of the output signal by reducing variations in a load applied to the phase shifter.

3. The method of claim 2, wherein reducing variations in the load applied to the phase shifter comprises using a variable capacitor to compensate for variations in the load.

4. The method of claim 2, further comprising receiving feedback from the WLAN receive chain, wherein variations in the load are reduced in response to feedback from the WLAN receive chain.

5. The method of claim 1, further comprising adjusting an amplitude of the output signal.

6. The method of claim 5, further comprising receiving feedback from the WLAN receive chain, wherein the amplitude is adjusted in response to feedback from the WLAN receive chain.

7. The method of claim 6, wherein feedback from the WLAN receive chain comprises one from the group consisting of a receive signal strength indicator (RSSI), a signal to noise ratio (SNR), a bit error rate (BER), and an error vector magnitude (EVM).

8. The method of claim 1, further comprising outputting the output signal to the WLAN receive chain.

9. The method of claim 1, further comprising selectively increasing a frequency of a clock signal generated by a clock source used by the Bluetooth transmit chain.

10. The method of claim 9, wherein the frequency of the clock signal is doubled based upon an operational state of the WLAN receive chain.

11. A device for wireless communication comprising a Bluetooth transmit chain, a wireless local area network (WLAN) receive chain, and an active interference cancellation module coupled to the Bluetooth transmit chain and the WLAN receive chain, wherein the active interference cancellation module includes a sampler configured to sample a signal from the Bluetooth transmit chain, a polyphase filter quadrature radio-frequency (RF) phase shifter configured to generate a plurality of quadrature components of the sampled signal, and combination logic configured to adjust a phase of the sampled signal by weighting and combining the plurality of quadrature components in response to digital baseband feedback to create an output signal.

12. The device of claim 11, wherein the active interference cancellation module further comprises a variable gain block in a signal path for a quadrature component configured to adjust the gain of the quadrature component.

13. The device of claim 12, wherein the variable gain block comprises at least one from the group consisting of a variable gain amplifier (VGA) and a variable capacitive divider.

14. The device of claim 11, wherein the active interference cancellation module further comprises a load adjuster configured to reduce variations in a load applied to the phase shifter.

15. The device of claim 14, wherein the load adjuster comprises a variable capacitor and the active interference cancellation module is configured to reduce variations in the load applied to the phase shifter by adjusting the variable capacitor.

16. The device of claim 15, further comprising a controller coupled to the active interference cancellation module and WLAN receive chain, the controller configured to receive feedback from the WLAN receive chain and send signals to the active interference cancellation module to adjust the variable capacitor in response to feedback from the WLAN receive chain.

17. The device of claim 11, wherein the active interference cancellation module is further configured to adjust an amplitude of output signal.

18. The device of claim 17, further comprising a controller coupled to the active interference cancellation module and WLAN receive chain, the controller configured to receive feedback from the WLAN receive chain and send signals to the active interference cancellation module to adjust the amplitude of the output signal in response to feedback from the WLAN receive chain.

19. The device of claim 18, wherein the feedback from the WLAN receive chain comprises one from the group consisting of a receive signal strength indicator (RSSI), a signal to noise ratio (SNR), a bit error rate (BER), and an error vector magnitude (EVM).

20. The device of claim 11, wherein the active interference cancellation module is further configured to output the output signal to the WLAN receive chain.

21. The device of claim 11, wherein the Bluetooth transmit chain includes a frequency source generating a clock signal, the device further comprising a circuit coupled to the frequency source of the Bluetooth transmit chain and configured to increase a frequency of the clock signal.

22. The device of claim 21, wherein the frequency of the clock signal is doubled based upon an operational state of the WLAN receive chain.