Equalizer Coefficient Update Using Phase Correction Symbols
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Solution Overview
Problem
Conventional adaptive equalizers in digital communication systems are inadequate for compensating for fast dynamic phase distortion, especially in lower signal-to-noise ratio environments, as they rely on decision-based phase locked loops that fail to correct phase variations accurately under these conditions.
Innovation Solution
The implementation of a phase correcting circuit within the equalizer that uses phase alignment modules and embedded phase correction symbols to realign the slicer error with the input signal phase, allowing for proper updating of equalizer coefficients using the LMS algorithm, even in low signal-to-noise ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional adaptive equalizers are used to compensate for distortion, then slowly fluctuating distortion can be corrected, but fast dynamic phase distortion cannot be properly compensated
Solution Approach 1:
The equalizer is divided into two independent paths: a conventional adaptive equalizer for slow distortion and a new phase correction circuit for fast phase variations. Each path handles specific types of distortion independently, allowing the system to compensate for both slow and fast dynamic phase distortions simultaneously without interference between the two functions.
Solution Approach 2:
A phase correction circuit is introduced as an intermediary component between the receiver and the adaptive equalizer. This circuit specifically targets and corrects fast dynamic phase variations before the signal enters the adaptive equalizer, enabling the overall system to handle both fast and slow distortion components effectively.
2Reliability
If adaptive equalizers operate in lower signal-to-noise ratio conditions, then error free operation is possible with error correction coding, but conventional phase correction circuits cannot reliably correct phase
Solution Approach 1:
The phase correction circuit uses a different operational approach that does not rely on decision-based phase locked loops. Instead, it employs a novel coefficient update mechanism that remains effective in lower signal-to-noise ratio conditions, maintaining phase correction accuracy where conventional circuits fail while enabling error-free operation with error correction coding.
3Productivity
If equalizer coefficients are updated using conventional methods, then coefficient adaptation occurs, but proper updates fail in the presence of fast dynamic phase variations
Solution Approach 1:
The coefficient update process is segmented into two independent mechanisms: conventional adaptive updates for slow distortion components and a new phase correction update path for fast phase variations. This segmentation allows each update mechanism to optimize for its specific distortion type, maintaining both update speed and coefficient accuracy across all distortion conditions.
Solution Approach 2:
The phase correction circuit implements a dedicated feedback path that continuously monitors and corrects phase variations in real-time. This feedback mechanism ensures that coefficient updates remain accurate even during fast dynamic phase changes, preventing the coefficient drift that occurs in conventional systems.
Data Source
AI summary
An update algorithm for equalizer coefficients in a communications system using phase correction symbols. Instead of using a traditional all symbols slicer update algorithm, the equalizer is updated during phase correction symbols for optimal performance in low signal-to-noise ratio conditions. In lower signal-to-noise ratio conditions, the equalizer uses a phase correction circuit to compensate for distortion caused by a communication channel when a demodulated data stream contains an unknown phase offsets resulting from a fast dynamic distortion. More specifically, the phase correction circuit uses a phase correction signal to correct for the unknown phase offsets in a demodulated data stream in lower signal-to-noise ratio conditions. The equalizer then corrects for distortion caused by the communication channel based upon the phase corrected demodulated data stream.