Self-interference channel estimation system and method

• US 9,787,460 B2
• Filed: 12/29/2015
• Issued: 10/10/2017
• Est. Priority Date: 07/16/2015
• Status: Active Grant

• Current Assignee: LGS Innovations LLC (CACI International Incorporated)
• Original Assignee: LGS Innovations LLC (CACI International Incorporated)
• Inventors: Brannon, Alan Scott, Pack, Riley Nelson, Baker, Benjamin Joseph
• Primary Examiner(s): NGO, RICKY QUOC
• Assistant Examiner(s): Truong, Lan Huong
• Application Number:
  US14/982,442
• Publication Number:
  US 20170019272A1
• Time in Patent Office: 651 Days
• CPC Class Codes: H03F 3/24 of transmitter output stages
• CPC Class Codes: H04B 1/0003 Software-defined radio [SDR] systems, i.e. systems wherein components typically implemented in hardware, e.g. filters or modulators/demodulators, are implented using software, e.g. by involving an AD or DA conversion stage such that at least part of the signal processing is performed in the digital domain digital baseband systems H04L25/00; digital modulation/demodulation H04L27/00; CDMA H04B1/707; TDMA H04B7/2643; image transmission H04N5/00
• CPC Class Codes: H04B 1/0042 Digital filtering H04B1/0035 takes precedence; digital filters per se H03H17/00
• 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 1/1036 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 1/401 for selecting or indicating operating mode
• CPC Class Codes: H04B 1/525 with means for reducing leakage of transmitter signal into the receiver
• CPC Class Codes: H04B 1/713 using frequency hopping
• CPC Class Codes: H04B 1/715 Interference-related aspects
• CPC Class Codes: H04B 15/00 Suppression or limitation of noise or interference by means associated with receiver H04B1/10
• CPC Class Codes: H04B 15/02 Reducing interference from electric apparatus by means located at or near the interfering apparatus
• CPC Class Codes: H04B 2001/0408 with power amplifiers
• CPC Class Codes: H04L 25/0212 of impulse response
• CPC Class Codes: H04L 25/025 using least-mean-square [LMS] method
• CPC Class Codes: H04L 5/14 Two-way operation using the same type of signal, i.e. duplex
• CPC Class Codes: H04L 5/1461 Suppression of signals in the return path, i.e. bidirectional control circuits

Abstract

The present application describes a method for characterizing a self-interference channel of a frequency division duplex transceiver including a transmitter and a receiver. The method includes transmitting, from a transmitter of a frequency division duplex transceiver in a transmission band, a transmission signal including a message signal and a swept tone that changes frequency from below an upper edge to above a lower edge of a reception band of a receiver, the self-interference channel being defined between the transmitter and the receiver of the frequency division duplex transceiver, such that at least a portion of the message signal leaks into a signal received the receiver, determining, at an infinite impulse response (IIR) filter of the receiver, an infinite impulse response of the self-interference channel based upon a reception of the swept tone swept at each frequency in the reception band, and estimating the self-interference channel, based upon the infinite impulse response.

Claims

1. A method for characterizing a self-interference channel of a frequency division duplex transceiver including a transmitter and a receiver, the method comprising:

transmitting, from a transmitter of a frequency division duplex transceiver in a transmission band, a transmission signal including a message signal and a swept tone that changes frequency from below an upper edge to above a lower edge of a reception band of a receiver, the self-interference channel being defined between the transmitter and the receiver of the frequency division duplex transceiver, such that at least a portion of the message signal leaks into a signal received by the receiver;

determining, at an infinite impulse response (IIR) filter of the receiver, an infinite impulse response of the self-interference channel based upon a reception of the swept tone swept at each frequency in the reception band; and

estimating the self-interference channel between the transmitter and the receiver, based upon the infinite impulse response.

2. The method of claim 1, wherein the transmitting comprises:

injecting, at the transmitter, a fixed tone outside the reception band in addition to the message signal and the swept tone; and

determining, at the receiver, a coefficient for automatic gain control and temperature variation based upon a change in a gain and a phase of the fixed tone.

3. The method of claim 2, further comprising:

up-converting, at the transmitter, the fixed tone and the swept tone centered around a central frequency of the reception band.

4. The method of claim 1, wherein the determining includes:

determining one or more coefficients of the IIR filter at the receiver, and

determining, a best-fitting curve indicating a gain response and a best-fitting curve indicating a phase response of the self-interference channel based upon the one or more coefficients.

5. The method of claim 1, further comprising:

providing, to the receiver, a sample of the transmission signal including the message signal and the swept tone prior to the transmitting,

wherein the estimating the self-interference channel includes comparing the sample with the swept tone and the portion of the message signal received at the receiver after the transmitting.

6. The method of claim 1, wherein the swept tone is transmitted periodically during the transmitting at discrete stepped frequencies.

7. The method of claim 1, wherein the transmitter and the receiver are collocated.

8. A self-interference channel estimation system, comprising:

a frequency division duplex transceiver including a transmitter and a receiver, the transmitter and the receiver forming a self-interference channel, the transmitter including;

a signal generator for generating a swept tone having a frequency ranging from an upper edge of the reception band to a lower edge of the reception band, and to generate a message signal, and

a combiner for up converting the swept tone and the message signal to a radio frequency signal centered about a center frequency of the reception band; and

the receiver including;

an infinite impulse response (IIR) filter for equalizing an infinite impulse response of the self-interference channel based upon a reception of the swept tone swept at each frequency in the reception band by the receiver over two receive paths, and a processor configured to estimate the self-interference channel between the transmitter and the receiver, based upon the equalized infinite impulse response.

9. The self-interference channel estimation system of claim 8, wherein the frequency division duplex receiver is located in a base station or a handset.

10. The self-interference channel estimation system of claim 8, wherein the transmitter and the receiver are collocated to form the self-interference channel.

11. The self-interference channel estimation system of claim 8, wherein the processor is configured to:

inject, at the transmitter, a fixed tone outside the reception band in addition to the message signal and the swept tone; and

determine, from the receiver, a coefficient for automatic gain control and temperature variation based upon a change in a gain and a phase of the fixed tone.

12. The self-interference channel estimation system of claim 11, wherein the processor is configured to:

up-convert, at the transmitter, the fixed tone and the swept tone centered around a central frequency of the reception band.

13. The self-interference channel estimation system of claim 11, wherein the processor is configured to:

determine one or more coefficients of the IIR filter at the receiver, and

determine, a best-fitting curve indicating a gain response and a best-fitting curve indicating a phase response of the self-interference channel based upon the one or more coefficients.

14. The self-interference channel estimation system of claim 11, wherein the processor is configured to:

provide, to the receiver, a sample of the transmission signal including the message signal and the swept tone prior to the transmitting,

wherein the estimating the self-interference channel includes comparing the sample with the swept tone and the portion of the message signal received at the receiver after a transmission.

15. The self-interference channel estimation system of claim 11, wherein the swept tone is transmitted periodically during the transmitting at discrete stepped frequencies.

16. A non-transitory computer-readable medium including computer executable instructions, which when executed by a processor cause the processor to:

transmit, from a transmitter of a frequency division duplex transceiver in a transmission band, a transmission signal including a message signal and a swept tone that changes frequency from below an upper edge to above a lower edge of a reception band of a receiver, the self-interference channel being defined between the transmitter and the receiver of the frequency division duplex transceiver, such that at least a portion of the message signal leaks into a signal received at the receiver;

determine, at an infinite impulse response (IIR) filter of the receiver, an infinite impulse response of the self-interference channel based upon a reception of the swept tone swept at each frequency in the reception band; and

estimate the self-interference channel between the transmitter and the receiver, based upon the infinite impulse response.

17. The non-transitory computer-readable medium of claim 16, wherein the computer executable instructions when executed by the processor further cause the processor to:

inject, at the transmitter, a fixed tone outside the reception band in addition to the message signal and the swept tone; and

determine, at the receiver, a coefficient for automatic gain control and temperature variation based upon a change in a gain and a phase of the fixed tone.

18. The non-transitory computer-readable medium of claim 17, wherein the computer executable instructions when executed by the processor further cause the processor to:

up-convert, at the transmitter, the fixed tone and the swept tone centered around a central frequency of the reception band.

19. The non-transitory computer-readable medium of claim 16, wherein the computer executable instructions when executed by the processor further cause the processor to:

determine one or more coefficients of the IIR filter at the receiver, and determine, a best-fitting curve indicating a gain response and a best-fitting curve indicating a phase response of the self-interference channel based upon the one or more coefficients.

20. The non-transitory computer-readable medium of claim 16, wherein the computer executable instructions when executed by the processor further cause the processor to:

provide, to the receiver, a sample of the transmission signal including the message signal and the swept tone prior to the transmitting,

wherein the estimation of the self-interference channel includes comparing the sample with the swept tone and the portion of the message signal received at the receiver after the transmitting.