Multipath Channel Impulse Response Estimation via Statistical Tracking

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Solution Overview

Problem

Current methods for determining channel impulse response (CIR) estimates in multipath transmission, especially under relay conditions with varying frequency offsets, are inaccurate, leading to residual frequency offsets and poor demodulation performance.

Innovation Solution

A system with an equalizer that includes a channel impulse response estimator and a statistical estimation module, such as a Kalman tracking filter or prediction error filter, to accurately estimate the state of multipath components and correct frequency offsets by modeling the time-varying evolution of CIR based on historical estimates.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If linear interpolation of CIR estimates is used, then device complexity is reduced, but measurement precision of CIR estimates deteriorates when substantial residual frequency offsets are present

Engineering Contradiction:

Improvecomplexity of CIR estimationVSAvoidaccuracy of CIR estimates

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent applies dynamics by transitioning from static linear interpolation to dynamic statistical estimation. The statistical estimation module adaptively models time-varying CIR characteristics using techniques like Kalman filtering, allowing the system to respond to changing channel conditions while maintaining manageable complexity through algorithmic efficiency.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the estimation parameters from simple linear interpolation coefficients to statistically optimized parameters. By using statistical estimation techniques that account for time-variability and frequency offsets, the system achieves higher measurement precision without proportionally increasing device complexity.

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If global frequency offset correction is applied, then overall frequency offset is reduced, but residual frequency offsets for individual multipath components remain substantial

Engineering Contradiction:

Improvefrequency offset correctionVSAvoidresidual frequency offset information

Core Design Contradiction:

Measurement precisionVSLoss of information

Solution Approach 1:

The patent segments the frequency offset correction process by component. Instead of applying a single global correction, the statistical estimation module estimates and corrects frequency offsets for each multipath component individually based on its specific characteristics, thereby eliminating residual offsets that would otherwise persist.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent applies local quality by tailoring the frequency offset correction to each specific multipath component. The statistical estimation adapts to the unique time-variability and frequency characteristics of each component, providing localized precision rather than uniform global correction.

Inventive Principle:

Principle #3Local quality

3Ease of manufacture

If linear interpolation assumes constant rate of change, then computational simplicity is maintained, but accuracy deteriorates when frequency offsets vary by multipath delay

Engineering Contradiction:

Improvecomputational simplicityVSAvoidCIR estimate accuracy

Core Design Contradiction:

Ease of manufactureVSMeasurement precision

Solution Approach 1:

The patent substitutes the mechanical linear interpolation approach with a statistical estimation system. This replacement uses probabilistic models and adaptive algorithms (such as Kalman filtering) that inherently account for varying rates of change and frequency offsets, achieving high accuracy without the computational burden of exhaustive methods.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentUS11552662B1Method for improving detection in multipath channels

Publication Date: 2023.01.10 ROCKWELL COLLINS INC

AI summary

A system for receiving multipath signals is disclosed. The system includes an equalizer that includes an input for a received data signal, wherein the received data comprises a first multipath component and a second multipath component. The equalizer further includes a channel impulse response estimator coupled to the input configured to determine one or more channel impulse response (CIR) estimates for the first multipath component and the second multipath component. The equalizer further includes a statistical estimation module coupled to the channel impulse response estimator configured to estimate a state of the first multipath component and the second multipath component based on the one or more channel impulse response estimates. The equalizer further includes a detector coupled to the statistical estimation module configured to detect data from the received data signal based on an estimated future state of the first multipath component and the second multipath component.