Feedback Signal Delay Estimation Using Correlation Differences
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Solution Overview
Problem
In digital nonlinear distortion compensation methods for wireless communications, accurately measuring the delay between reference and feedback signals is challenging, leading to suboptimal distortion compensation performance due to timing mismatches and increased arithmetic throughput and circuit complexity.
Innovation Solution
A delay quantity estimation apparatus that calculates correlation values between reference and feedback signals delayed by different values, using a difference-based approach to estimate the optimal delay, reducing the need for extensive memory storage and multiple measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the correlation operation method is used to measure delay by storing signals in memory and delaying on clk and tap units, then delay measurement capability is achieved, but arithmetic errors increase and measurement precision deteriorates in the vicinity of maximum correlation value
Solution Approach 1:
The patent replaces the conventional correlation operation method with a cross-product operation method. Instead of using complex correlation calculations that require storing signals in memory and performing arithmetic operations on delayed signals, the invention uses a simpler cross-product operation between the reference signal and feedback signal. This substitution eliminates the arithmetic errors associated with correlation operations while maintaining delay measurement capability, directly resolving the contradiction between measurement precision and reliability.
Solution Approach 2:
The patent changes the fundamental parameter of the measurement operation from correlation coefficient calculation to cross-product summation. By transforming the measurement approach from finding maximum correlation value to calculating the sum of cross-products, the invention avoids the arithmetic errors that occur in the vicinity of maximum correlation values. This parameter change enables accurate delay measurement without the reliability issues of the conventional method.
2Difficulty of detecting and measuring
If signals are stored in memory for correlation operation, then delay measurement is enabled, but circuit complexity increases
Solution Approach 1:
The patent extracts and eliminates the memory storage component from the delay measurement system. By using cross-product operations that can be performed on streaming signals without storing them in memory, the invention removes the need for complex memory structures while maintaining the ability to measure delay between reference and feedback signals. This extraction directly reduces circuit complexity while preserving measurement capability.
Solution Approach 2:
The patent replaces expensive, complex memory-based correlation operation structures with simpler, disposable computational operations. The cross-product method uses basic arithmetic operations that do not require persistent storage, effectively using simple computational steps instead of complex memory structures. This approach reduces circuit complexity while maintaining functional equivalence for delay measurement.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method allows for accurate estimation of the delay quantity with reduced circuit complexity and increased efficiency by calculating correlation values at identical signal timings, improving distortion compensation performance while minimizing arithmetic throughput.
Implementation Method 1
A method using a correlation operation is known as the method of measuring the delay of the FB signal with respect to the Ref signal. This method is a method of storing the FB signal and the Ref signal in a memory, delaying the FB signal on the unit of 'clk' and the unit of 'tap'
Data Source
AI summary
A delay quantity estimation apparatus comprises a first correlation value arithmetic unit to calculate a first correlation value as a correlation value between a first input signal and a feedback signal delayed with a first delay value; a second correlation value arithmetic unit to calculate a second correlation value as a correlation value between the first input signal and a feedback signal delayed with a second delay value; and a delay quantity estimation unit to estimate a delay quantity of the feedback signal with respect to the input signal on the basis of the first difference value as a difference between the first correlation value and the second correlation value, wherein the second delay value is a value given by adding a certain value to the first delay value.