Blind Channel Equalizer with Dynamic Correction Coefficient
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Solution Overview
Problem
Current blind channel equalizers in radiofrequency transmission face challenges in automotive applications due to high processing power requirements and instability caused by varying signal power, which leads to divergence and interference with downstream modules.
Innovation Solution
A blind channel equalizer device with an adaptable linear digital filter, power estimator, and adaptive coefficient calculation using a cost function with a correction coefficient that accounts for signal power variations, avoiding the need for automatic gain control and optimizing performance for automotive-hardened processors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a blind channel equalizer uses a conventional cost function with fixed correction coefficient, then the equalization algorithm is simple to implement, but the equalization process becomes unstable and diverges when signal power varies significantly
Solution Approach 1:
The correction coefficient is transformed from a fixed value to a dynamic value that adapts to signal power variations. The patent introduces a dynamic correction coefficient μ[n] = μ₀/σ²[n], where σ²[n] is the instantaneous signal power estimate. This allows the equalizer to automatically adjust its adaptation speed according to the current signal conditions, maintaining stability across varying power levels without requiring complex manual tuning or multiple processing stages.
Solution Approach 2:
The patent implements a feedback mechanism where the instantaneous signal power σ²[n] is continuously estimated and fed back into the correction coefficient calculation. This closed-loop feedback allows the system to sense power variations and automatically compensate for them by adjusting the correction coefficient, thereby preventing divergence while maintaining algorithmic simplicity.
2Reliability
If an automotive-hardened processor is used to meet automotive environmental specifications, then the device is reliable in harsh environments, but the processing power and performance are reduced compared to consumer processors
Solution Approach 1:
The patent changes the key parameter of the adaptation algorithm from a fixed correction coefficient to a dynamically adjusted one based on signal power. This parameter change simplifies the computational requirements per iteration while improving numerical stability, making the algorithm more suitable for execution on resource-constrained automotive-hardened processors that prioritize reliability over raw processing power.
Solution Approach 2:
The patent replaces the need for expensive, high-performance consumer processors with a simpler algorithm that can run efficiently on cheaper, lower-power automotive-hardened processors. By optimizing the mathematical formulation to require fewer computational resources, the solution enables deployment on processors specifically designed for automotive environments, accepting reduced processing power in exchange for improved reliability and cost-effectiveness.
3Speed
If the correction coefficient is increased to speed up convergence, then the equalization converges faster, but the equalizer becomes more sensitive to signal power variations and diverges more easily
Solution Approach 1:
The correction coefficient is made dynamic rather than fixed, allowing it to automatically scale with signal power conditions. During high-power signals, the coefficient decreases to prevent divergence; during low-power signals, it increases to maintain convergence speed. This dynamic adaptation resolves the trade-off between convergence speed and stability, enabling fast convergence without sacrificing reliability.
Data Source
AI summary
A blind channel equalizer device for a radiofrequency receiver suitable for modulating the constant envelope signal of the transmission includes: an adjustable linear digital filter, defined at a point in time by the coefficients) thereof, able to filter an input signal in order to produce an output signal; an estimator able to estimate a power of the input signal; an adapter able to adapt the filter by calculating the coefficients of the filter at a point in time by subtracting, from the filter coefficients at a preceding point in time, the gradient of a cost function assigned with a correction coefficient. The cost function includes a first distance criterion between the square of the output signal and the power, wherein the correction coefficient is a product including a constant convergence coefficient and a scaling coefficient inversely proportional to the square of the power. Also disclosed is a related Radiofrequency receiver.