Self-Interference Channel Estimation System and Method

• US 20170353288A1
• Filed: 08/24/2017
• Published: 12/07/2017
• 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
• Granted Patent: US 10,574,428 B2
• Time in Patent Office: 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 self-interference channel estimation system. The system includes a signal generator configured to generate a swept tone having a frequency ranging from an upper edge of a reception band to a lower edge of the reception band, and configured to generate a message signal. The system includes an infinite impulse response (IIR) filter configured to determine an infinite impulse response of a self-interference channel based upon the swept tone. The system includes a processor configured to characterize the self-interference channel based upon the infinite impulse response.

Claims

1. A method for characterizing a self-interference channel of a transceiver, the method comprising:

transmitting 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;

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

characterizing the self-interference channel based upon the infinite impulse response.

2. The method of claim 1, wherein the transmitting step is carried out from a transmitter of a frequency division duplex transceiver including the transmitter and the receiver, the step of transmitting includes:

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, wherein the step of transmitting further includes:

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 characterizing step 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 within the reception band.

7. The method of claim 1, wherein the transmitter and the receiver are collocated such that at least a portion of the message signal leaks into a signal received the receiver.

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

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

an infinite impulse response (IIR) filter configured to determine an infinite impulse response of a self-interference channel based upon the swept tone, and

a processor configured to characterize the self-interference channel based upon the infinite impulse response.

9. The self-interference channel estimation system of claim 8, further comprising:

a frequency division duplex transceiver including a transmitter and a receiver, the transmitter and the receiver forming a self-interference channel, wherein the signal generator is included in the transmitter and the IIR filter is included in the receiver.

10. The self-interference channel estimation system of claim 9, wherein the transmitter includes a combiner configured to up convert the swept tone and the message signal to a radio frequency signal centered about a center frequency of the reception band.

11. The self-interference channel estimation system of claim 9, 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 9, 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 9, 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, and

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

14. The self-interference channel estimation system of claim 9, wherein the transmitter and the receiver are collocated.

15. The self-interference channel estimation system of claim 8, wherein the swept tone is received over multiple paths in the self-interference channel.

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, 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;

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

characterize 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 collocated with the receiver, 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 16, wherein the transmitter and the receiver are part of a wireless handset or a base station.

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

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 being transmitted,

wherein the self-interference channel is characterized by a comparison the sample with the swept tone and the portion of the message signal received at the receiver after a transmission.