BACKSCATTER ESTIMATION USING PROGRESSIVE SELF INTERFERENCE CANCELLATION

• US 20160266245A1
• Filed: 11/14/2014
• Published: 09/15/2016
• Est. Priority Date: 08/09/2013
• Status: Active Grant

• Current Assignee: Board of Trustees of the Leland Stanford Junior University (Stanford Management Co.)
• Original Assignee: Board of Trustees of the Leland Stanford Junior University (Stanford Management Co.)
• Inventors: JOSHI, Kiran, BHARADIA, Dinesh, KATTI, Sachin
• Granted Patent: US 11,163,050 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G01S 13/003 Bistatic radar systems; Multistatic radar systems
• CPC Class Codes: G01S 13/42 Simultaneous measurement of distance and other co-ordinates indirect measurement G01S13/46
• CPC Class Codes: G01S 7/038 Feedthrough nulling circuits
• CPC Class Codes: G01S 7/292 Extracting wanted echo-signals

Abstract

Techniques for estimating one or more backscatter signals reflected from one or more objects are disclosed. In one example, a backscatter sensor includes, in part, a receiver for receiving a composite signal comprising one or more reflections of a transmitted signal, each reflection being reflected by one of a plurality of objects; and a processor configured to estimate at least a first backscatter component of the composite signal using a progressive interference cancellation technique. The first backscatter component of the composite signal corresponds to a reflection of the transmitted signal from a first object. In one embodiment, the backscatter sensor includes multiple receivers and/or one or more transmitters.

Claims

1. A backscatter sensor, comprising:

a receiver for receiving a composite signal comprising one or more reflections of a transmitted signal, each reflection being reflected by one of a plurality of objects; and

a processor configured to;

estimate at least a first backscatter component of the composite signal using a progressive interference cancellation technique, wherein the first backscatter component of the composite signal corresponds to a reflection of the transmitted signal from a first object.

2. The backscatter sensor of claim 1, wherein the receiver further comprises:

a plurality of receive antennas, each receive antenna being coupled to a receive chain, wherein each receive chain receives a modified copy of the composite signal.

3. The backscatter sensor of claim 1, further comprising:

a transmitter for transmitting the transmitted signal, and wherein the processor further receives a sample of the transmitted signal.

4. The backscatter sensor of claim 3, wherein the transmitter comprises one or more transmitters, each transmitter transmitting a signal.

5. The backscatter sensor of claim 1, wherein the processor is further configured to estimate at least one of an amplitude of the first backscatter component, a phase of the first backscatter component and a time delay between transmission of the transmitted signal and reception of the first backscatter component.

6. The backscatter sensor of claim 1, wherein the processor is further configured to:

remove the estimated first backscatter component from the composite signal to generate a second signal; and

estimate a second backscatter component using the second signal, the second backscatter component corresponding to a reflection of the transmitted signal from a second object.

7. The backscatter sensor of claim 1, wherein the first object is the closest object to the receiver among the plurality of objects.

8. The backscatter sensor of claim 1, wherein the processor is further configured to estimate one or more parameters associated with at least the first backscatter component using a linear optimization technique.

9. The backscatter sensor of claim 8, wherein the processor is further configured to estimate the one or more parameters in accordance with the following expression:

10. The backscatter sensor of claim 1, wherein the receiver is further configured to receive the composite signal during a plurality of consecutive non-overlapping time windows, and the processor is further configured to:

estimate one or more parameters of the first backscatter component based at least on a first portion of the composite signal received in a first window; and

iteratively estimate parameters of a next backscatter component based on a second portion of the composite signal received in a next consecutive window.

11. The backscatter sensor of claim 10, wherein the consecutive non-overlapping windows have a variable size.

12. The backscatter sensor of claim 1, wherein the processor is further configured to estimate the at least the first backscatter component using a Sequential Convex Programming (SCP) algorithm.

13. The backscatter sensor of claim 12, wherein the processor is further configured to generate an initial estimate for the SCP algorithm using a continuous basis pursuit (CBP) algorithm.

14. The backscatter sensor of claim 1, wherein the processor is further configured to estimate the at least the first backscatter component using a continuous basis pursuit (CBP) algorithm.

15. The backscatter sensor of claim 1, wherein the processor is further configured to estimate a Doppler frequency corresponding to each object.

16. A method for sensing backscatter signals, comprising:

receiving a composite signal comprising one or more reflections of a transmitted signal, each reflection being reflected by one of a plurality of objects; and

estimating at least a first backscatter component of the composite signal using a progressive interference cancellation technique, wherein the first backscatter component of the composite signal corresponds to a reflection of the transmitted signal from a first object.

17. The method of claim 16, further comprising:

receiving a plurality of composite signals by a plurality of receive antennas, each receive antenna being coupled to a receive chain.

18. The method of claim 16, further comprising:

transmitting one or more signals using one or more transmit antennas; and

estimating one or more backscatter components corresponding to each transmitted signal.

19. The method of claim 16, wherein estimating at least a first backscatter component comprises estimating at least one of an amplitude of the first backscatter component, a phase of the backscatter component, and a time delay between transmission of the transmitted signal and reception of the first backscatter component, time of flight of the first backscatter component.

20. The method of claim 16, further comprising:

removing the estimated first component from the composite signal to generate a second signal; and

estimating a second backscatter component using the second signal, the second backscatter component corresponding to a reflection of the transmitted signal from a second object.

21. The method of claim 16, wherein the first object is the closest object to the receiver among the plurality of objects.

22. The method of claim 16, further comprising:

estimating one or more parameters associated with at least the first backscatter component using a linear optimization technique.

23. The method of claim 22, wherein the linear optimization technique comprises solving the following expression:

24. The method of claim 16, further comprising:

receiving the composite signal during a plurality of consecutive non-overlapping time windows; and

estimating one or more parameters of the first backscatter component based at least on a first portion of the composite signal received in a first window; and

iteratively estimating parameters of a next backscatter component based on a second portion of the composite signal received in a next consecutive window.

25. The method of claim 24, wherein the consecutive time windows correspond to different sizes.

26. The method of claim 16, further comprising:

estimating the at least the first backscatter component using a Sequential Convex Programming (SCP) algorithm.

27. The method of claim 26, further comprising:

generating an initial estimate for the SCP algorithm using a continuous basis pursuit (CBP) algorithm.

28. The method of claim 16, further comprising:

estimating the at least the first backscatter component using a continuous basis pursuit (CBP) algorithm.

29. The method of claim 16, further comprising:

estimating a Doppler frequency corresponding to each object.