Symbol Timing Tracking with High-Order Loops for Self-Noise Suppression
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current timing synchronization techniques in communications systems fail to effectively suppress self-noise, especially in systems with high-order signal constellations and asymmetric channels, leading to inefficiencies and errors in data recovery.
Innovation Solution
A symbol-timing tracking system that includes a nonlinear timing error detector and a high-order loop filter, capable of filtering out self-noise and tracking higher-order dynamics, such as clock timing-ramps and frequency-ramps, using an infinite impulse response filter to correct sampling rates and timing errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a nonlinear timing error detector is used to achieve robust timing error detection in high-order signal constellations, then timing detection capability is improved, but self-noise is generated that degrades system performance
Solution Approach 1:
A high-order loop filter is introduced as an intermediary component between the nonlinear timing error detector and the timing recovery loop. This filter acts as a mediator that selectively attenuates the self-noise generated by the nonlinear TED while preserving the useful timing error signal, thereby resolving the contradiction between maintaining robust timing detection and suppressing harmful self-noise
Solution Approach 2:
The patent changes the filtering parameters by using high-order loop filters with specific pole-zero configurations. By adjusting the filter order and characteristics, the system optimizes the trade-off between suppressing self-noise and maintaining timing detection accuracy, transforming the parameter set of the filtering stage to achieve superior noise rejection
2Device complexity
If conventional loop filters are used to simplify the filtering stage, then device complexity is reduced, but the ability to track higher-order dynamics such as clock timing-ramps and frequency-ramps is insufficient
Solution Approach 1:
The patent implements dynamic filtering by using high-order loop filters that can adaptively track time-varying signal characteristics. The filter design incorporates dynamic response characteristics that enable it to follow clock timing-ramps and frequency-ramps, transforming the static filtering approach into a dynamic one that maintains reliability under varying operational conditions
Solution Approach 2:
The filtering function is segmented into multiple stages with different characteristics. The high-order loop filter is divided into feedforward and feedback sections, each handling specific aspects of the signal processing. This segmentation allows the system to track higher-order dynamics effectively while managing overall complexity through modular design
3Reliability
If high-order loop filters are used to filter out self-noise and track higher-order dynamics, then timing synchronization performance is improved, but device complexity increases
Solution Approach 1:
The high-order loop filter employs feedback mechanisms where the filtered output is fed back to adjust the filtering process. This feedback approach allows the system to achieve superior timing synchronization performance by continuously adapting to signal conditions, while the feedback structure itself provides a systematic way to manage the complexity of the high-order filter design
Data Source
AI summary
Some implementations of the disclosure are directed to symbol-timing tracking systems and methods. A symbol-timing tracking system may include: an ADC to generate a digital signal by sampling an analog signal received at a receiver; an interpolator to adjust a sampling rate of the digital signal; a receive filter to apply a receive filtering function to the digital signal to generate a filtered signal; a timing error detector configured to generate a timing error signal from the filtered signal; a high-order loop filter to filter the timing error signal to generate a filtered timing error signal; and a numerically controlled oscillator to control timing data based on the filtered timing error signal and provide the timing data to the interpolator, wherein the interpolator is to correct for timing of the digital signal and adjust the sampling rate of the digital signal based on the timing data.