Passive intermodulation cancellation

• US 10,141,961 B1
• Filed: 05/18/2017
• Issued: 11/27/2018
• Est. Priority Date: 05/18/2017
• Status: Active Grant

• Current Assignee: NanoSemi, Incorporated (Maxlinear Incorporated)
• Original Assignee: NanoSemi, Incorporated (Maxlinear Incorporated)
• Inventors: Huang, Yanyu, Mahmood, Zohaib, Li, Yan, Megretski, Alexandre, Kim, Helen H.
• Primary Examiner(s): Puente, Eva
• Application Number:
  US15/598,613
• Publication Number:
  US 20180337700A1
• Time in Patent Office: 558 Days
• Field of Search: 375285, 375219, 37524008, 455454, 455295
• CPC Class Codes: H04B 1/0475 with means for limiting noise, interference or distortion H04B1/0483 takes precedence
• CPC Class Codes: H04B 1/10 Means associated with receiver for limiting or suppressing noise or interference
• CPC Class Codes: H04B 1/12 Neutralising, balancing, or compensation arrangements
• CPC Class Codes: H04B 1/525 with means for reducing leakage of transmitter signal into the receiver
• CPC Class Codes: H04L 5/1423 for simultaneous baseband signals
• CPC Class Codes: H04L 7/0087 Preprocessing of received signal for synchronisation, e.g. by code conversion, pulse generation or edge detection
• CPC Class Codes: H04W 88/02 Terminal devices

Abstract

A received signal is enhanced by removing distortion components of a concurrently transmitted signal. A received signal is acquired in a receive frequency band concurrently with transmission of a transmit signal in a transmit frequency band. The received signal includes an intermodulation distortion component of the transmit signal. A representation of the transmit signal is processed using a non-linear predictor to output a distortion signal representing predicted distortion components in the received signal. The received signal is enhanced using the distortion signal by removing the predicted distortion components from the received signal corresponding to the distortion signal.

Claims

1. A method for enhancing a received signal to remove distortion components of a concurrently transmitted signal, the method comprising:

receiving a reference signal corresponding to a transmit signal transmitted in a radio frequency transmission band;

receiving via receiving circuitry a received signal acquired in a radio frequency reception band concurrently with transmission of the transmit signal in the transmit frequency band, wherein the received signal includes a distortion component of the transmit signal, and wherein the transmit frequency band and the receive frequency band are non-overlapping bands;

upsampling the reference signal to yield an upsampled transmit signal, and upsampling the received signal to yield an upsampled received signal, wherein the upsampled reference signal and the upsampled received signal have a same sampling rate, and wherein a relative frequency between the upsampled reference signal and the upsampled received signal matches a relative frequency between the transmit frequency band and the receive frequency band;

passing the upsampled reference signal to a configurable predictor configured with predictor parameters, the configurable predictor providing an upsampled distortion signal determined from the upsampled reference signal as input;

downsampling the upsampled distortion signal to yield a distortion signal;

enhancing the received signal using the distortion signal by removing components from the received signal corresponding to the distortion signal;

correlating the upsampled distortion signal and the upsampled received signal to determine a relative delay, wherein upsampling the reference signal includes synchronizing the upsampled reference signal and the upsampled received signal according to the relative delay; and

estimating the parameters for the predictor using the upsampled reference signal and the upsampled received signal.

2. A method for enhancing a received signal to remove distortion components of a concurrently transmitted signal, the method comprising:

receiving the received signal acquired in a reception frequency band concurrently with transmission of a transmit signal in a transmission frequency band, wherein the received signal includes a distortion component of the transmit signal;

processing a reference signal representing the transmit signal using a non-linear predictor to output an upsampled distortion signal comprising a predicted distortion component corresponding to the transmit signal;

enhancing the received signal to yield an enhanced received signal using based on the upsampled distortion signal by removing at least some of the distortion component of the transmit signal from the received signal according to the predicted distortion component; and

providing the enhance received signal.

3. The method of claim 2 further comprising:

providing the reference signal for causing transmission of the transmit signal in a transmission frequency band.

4. The method of claim 3 wherein transmission of the transmit signal is via transmission circuitry and wherein the received signal is received via first receiving circuitry that is coupled to or that shares elements with the transmission circuitry.

5. The method of claim 3 wherein the transmission circuitry and the receiving circuitry share a passive element causing intermodulation distortion included in the received signal, wherein the distortion component comprises at least the intermodulation distortion caused by the passive element.

6. The method of claim 2 further comprising:

receiving the reference signal via second receiving circuitry based on a propagation of the transmit signal.

7. The method of claim 2 wherein processing the reference signal comprises:

upsampling the reference signal to yield an upsampled transmit signal at an upsampled sampling rate, the transmit frequency band corresponding to an upsampled transmit band in the upsampled transmit signal; and

passing the upsampled transmit signal to a configurable predictor configured with predictor parameters, the configurable predictor providing an upsampled distortion signal determined from the upsampled transmit signal as input.

8. The method of claim 6 further comprising:

downsampling the upsampled distortion signal to yield the distortion signal retaining a part of the upsampled signal in an upsampled receiving band corresponding the reception frequency band, the upsampled receiving band being distinct from the upsampled transmit band.

9. The method of claim 8 wherein enhancing the received signal comprises

subtracting the distortion signal from the received signal.

10. The method of claim 2 further comprising:

upsampling the reference signal to yield an upsampled transmit signal at an upsampled sampling rate, the transmit frequency band corresponding to an upsampled transmit band in the upsampled transmit signal;

upsampling the received signal to yield an upsampled received signal at the upsampled sampling rate, the reception frequency band corresponding to an upsampled reception band in the upsampled received signal, wherein the upsampled reception band and the upsampled transmit band in the upsampled transmit signal have a same frequency relationship as the transmit frequency band and the receive frequency band.

11. The method of claim 10 wherein upsampling the reference signal includes introducing a time delay of the upsampled transmit signal relative to the upsampled received signal.

12. The method of claim 11 further comprising:

determining a correlation time between the distortion signal and the received signal; and

setting the time delay for the upsampled received signal according to the correlation time.

13. The method of claim 12 wherein processing the reference signal using a non-linear predictor comprises passing the upsampled transmit signal to a predictor to yield an upsampled distortion signal, and determining the correlation time comprises determining a correlation time between the upsampled distortion signal and the upsampled received signal.

14. The method of claim 10 wherein processing the reference signal using a non-linear predictor comprises passing the upsampled transmit signal to a configurable predictor configured with predictor parameters.

15. The method of claim 14 wherein processing the reference signal further comprises accepting an upsampled distortion signal from the configurable predictor, and downsampling the upsampled distortion signal retaining the upsampled reception band to yield the distortion signal.

16. The method of claim 14 further comprising determining the predictor parameters comprises setting the parameters to predict the upsampled received signal from the upsampled transmit signal.

17. The method of claim 14 wherein the non-linear predictor comprises a time domain non-linear function that yields a time sample of the upsampled distortion signal as a function of multiple time samples of the upsampled transmit signal.

18. A signal processing apparatus for use with a transceiver to enhance a received signal based on a signal received at the transceiver in a reception band to remove distortion components of a concurrently transmitted signal in a transmission band, the apparatus comprising:

a synchronizer configured to accept a reference signal representing a transmit signal and a received signal, and to provide an upsampled transmit signal and an upsampled received signal each sampled at a same sampling rate such that a frequency relationship between the transmission band and the reception band corresponds to a frequency relationship between the upsampled transmit signal and the upsampled received signal, wherein the synchronizer is further configured to apply a delay to synchronize the upsampled received signal and the upsampled transmit signal; and

a canceller including a predictor configured to receive the upsampled transmit signal and the upsampled received signal, to adaptively predict a distortion signal comprising distortion components of upsampled transmit signal, and to enhance the received signal using the distortion signal.

19. A non-transitory computer readable medium storing a data structure which is operated upon by a program executable on a computer system, the program operating on the data structure to perform a portion of a process to fabricate an integrated circuit including circuitry described by the data structure, the circuitry described in the data structure including a signal processor for use with a transceiver to enhance a received signal based on a signal received at the transceiver in a reception band to remove distortion components of a concurrently transmitted signal transmitted from the transceiver in a transmission band, the signal processor comprising:

a synchronizer configured to accept a reference signal representing a transmit signal and a received signal, and to provide an upsampled transmit signal and an upsampled received signal each sampled at a same sampling rate such that a frequency relationship between the transmission band and the reception band corresponds to a frequency relationship between the upsampled transmit signal and the upsampled received signal, wherein the synchronizer is further configured to apply a delay to synchronize the upsampled received signal and the upsampled transmit signal; and

a canceller including a predictor configured to receive the upsampled transmit signal and the upsampled received signal, to adaptively predict a distortion signal comprising distortion components of upsampled transmit signal, and to enhance the received signal using the distortion signal.

20. A method for enhancing a received signal to remove distortion components of a concurrently transmitted signal, the method comprising:

receiving the received signal acquired in a reception frequency band concurrently with transmission of a transmit signal in a transmission frequency band, wherein the received signal includes a distortion component of the transmit signal;

processing a reference signal representing the transmit signal using a non-linear predictor to output a distortion signal comprising a predicted distortion component corresponding to the transmit signal, wherein processing the reference signal comprises;

upsampling the reference signal to yield an upsampled transmit signal at an upsampled sampling rate, the transmit frequency band corresponding to an upsampled transmit band in the upsampled transmit signal; and

passing the upsampled transmit signal to a configurable predictor configured with predictor parameters, the configurable predictor providing an upsampled distortion signal determined from the upsampled transmit signal as input;

enhancing the received signal to yield an enhanced received signal using the distortion signal by removing at least some of the distortion component of the transmit signal from the received signal according to the predicted distortion component; and

providing the enhance received signal.

21. A method for enhancing a received signal to remove distortion components of a concurrently transmitted signal, the method comprising:

receiving the received signal acquired in a reception frequency band concurrently with transmission of a transmit signal in a transmission frequency band, wherein the received signal includes a distortion component of the transmit signal;

processing a reference signal representing the transmit signal using a non-linear predictor to output a distortion signal comprising a predicted distortion component corresponding to the transmit signal;

enhancing the received signal to yield an enhanced received signal using the distortion signal by removing at least some of the distortion component of the transmit signal from the received signal according to the predicted distortion component; and

providing the enhance received signal;

wherein the method further comprises;

upsampling the reference signal to yield an upsampled transmit signal at an upsampled sampling rate, the transmit frequency band corresponding to an upsampled transmit band in the upsampled transmit signal; and

upsampling the received signal to yield an upsampled received signal at the upsampled sampling rate, the reception frequency band corresponding to an upsampled reception band in the upsampled received signal, wherein the upsampled reception band and the upsampled transmit band in the upsampled transmit signal have a same frequency relationship as the transmit frequency band and the receive frequency band.