Backscatter Estimation via Progressive Self-Interference Cancellation
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Solution Overview
Problem
Existing systems face challenges in accurately estimating backscatter signals due to self-interference from transmitted signals and stronger nearby reflections, which overwhelm weaker reflections, limiting the dynamic range of commercially available radios.
Innovation Solution
A backscatter sensor system employing progressive self-interference cancellation techniques, using multiple receive antennas and a processor to estimate backscatter components by removing strong interference and applying linear optimization and Sequential Convex Programming algorithms to disentangle closely spaced reflections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If transmitted signal power is increased to improve detection capability, then backscatter signal strength improves, but self-interference increases and drowns out backscatter signals
Solution Approach 1:
The patent segments the received signal into multiple components: transmitted signal leakage, backscatter signals from different objects, and noise. By applying progressive interference cancellation, each component is separately estimated and processed, allowing the system to isolate and measure weak backscatter signals even in the presence of strong transmitted signal leakage.
Solution Approach 2:
The patent converts the harmful self-interference from the transmitted signal into a useful component for backscatter estimation. By using the known transmitted signal waveform and channel estimates, the system reconstructs the leakage component and subtracts it from the received signal, thereby eliminating the interference and revealing the backscatter signals.
2Measurement precision
If dynamic range of radio is increased to capture both strong and weak reflections, then all backscatter components can be detected, but device complexity and cost increase
Solution Approach 1:
The patent introduces digital signal processing algorithms as an intermediary between the radio hardware and the backscatter detection task. Instead of relying on hardware with extended dynamic range, the system uses software-based progressive interference cancellation to effectively extend the usable dynamic range of standard commercial radios.
Solution Approach 2:
The patent changes the processing parameters of the received signal through multiple stages of cancellation and estimation. By iteratively adjusting cancellation levels and estimation parameters, the system extracts backscatter signals across a wide effective dynamic range using standard radio hardware.
3Measurement precision
If nearby reflectors are present to provide strong reflections, then signal strength improves, but weak reflections from farther objects get swamped out
Solution Approach 1:
The patent performs preliminary estimation of strong reflection components from nearby objects before detecting weaker reflections from distant objects. By first identifying and canceling the dominant nearby reflections, the system prepares the signal in advance to reveal the weaker distant reflections that would otherwise be masked.
Solution Approach 2:
The patent employs dynamic adaptive processing where the cancellation depth and estimation parameters are adjusted based on the relative strengths of different reflection components. This dynamic approach allows the system to handle varying scenarios with different numbers and strengths of reflectors.
Data Source
AI summary
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.