Adaptive Channel Estimator Clock Phase Compensation
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Solution Overview
Problem
Existing timing recovery systems face interference between channel estimation and clock recovery due to fixed channel estimation methods, which are unable to adapt to time-varying channel responses, leading to potential errors and shifts in recovered data symbols.
Innovation Solution
A mechanism is introduced that uses an adaptive channel estimator with FIR filters whose tap weights adjust based on time-variant channel responses, employing a Center of Filter (COF) value to detect and compensate clock delay corrections, thereby reducing interaction with the timing recovery loop.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If fixed channel estimation is used, then device complexity is reduced, but channel estimation precision deteriorates due to inability to adapt to time-varying channel responses
Solution Approach 1:
The patent implements an adaptive channel estimator that dynamically adjusts the FIR filter tap weights based on time-variant channel responses. The channel estimator transitions from a fixed structure to a dynamic one that continuously adapts to changing channel conditions, resolving the contradiction between fixed structure simplicity and adaptation capability.
Solution Approach 2:
The patent changes the parameters of the channel estimation filter by adjusting the tap weights of the FIR filter according to detected channel response variations. This parameter adaptation allows the system to maintain high estimation precision while managing complexity through structured adaptation mechanisms.
2Measurement precision
If channel estimation corrects clock delay, then channel estimation precision is improved, but timing recovery stability deteriorates due to interference with clock recovery process
Solution Approach 1:
The patent segments the clock delay correction function into two separate components: channel estimation handles channel response compensation while timing recovery handles clock phase synchronization. This functional segmentation prevents interference between the two processes while maintaining their respective precision and stability.
Solution Approach 2:
The patent extracts the clock delay correction capability from the channel estimation process and relocates it to the timing recovery loop. This extraction eliminates the harmful interaction between channel estimation and timing recovery while preserving the beneficial clock delay correction functionality in its appropriate domain.
3Measurement precision
If adaptive channel estimation is used, then channel estimation precision is improved through time-variant adaptation, but device complexity increases due to additional adaptation mechanisms
Solution Approach 1:
The patent implements a feedback mechanism where the adaptive channel estimator uses detected channel response variations to adjust its tap weights. This feedback loop enables continuous adaptation to time-variant channels while maintaining a structured approach that manages the complexity through systematic parameter updates.
Solution Approach 2:
The adaptive channel estimator serves multiple functions: it performs channel response estimation, adapts to time-variant conditions, and provides corrected signals to the timing recovery loop. This multi-functionality justifies the increased complexity by delivering comprehensive channel compensation capabilities.
Data Source
AI summary
System and method of timing recovery for recovering a clock signal with reduced interaction between an adaptive channel estimator and the overall timing loop for correcting clock phase. The channel response estimation in the timing recovery loop is dynamically adapted to the current channel response that varies over time. The channel estimator includes compensation logic operable to detect and compensate a correction of clock phase ascribed to the channel estimator. The compensation logic can calculate the offset between a center of filter (COF) value and a COF nominal value, the offset indicative of the amount and direction of clock phase correction contributed by the channel estimator. Based on the offset, the compensation logic adjusts the estimates channel response by adjusting the tap weights of the channel estimator to correct the offset, thereby compensating the clock phase correction.