Digital Receiver Equalizer Alphabet Decentering Compensation
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Solution Overview
Problem
Digital receivers using conventional MMSE-DFE equalizers exhibit reduced reception performance, characterized by high bit error rates, due to the non-centering of the modulation alphabet.
Innovation Solution
A digital data receiver is designed with an equalizer that adds a non-zero scalar component to the linear combination of samples to compensate for the decentering of the modulation alphabet, thereby improving symbol detection efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional MMSE-DFE equalizer is used without compensation for non-centered alphabet, then the device complexity is reduced, but the reception performance deteriorates with high bit error rates
Solution Approach 1:
The equalizer pre-calculates and stores compensation values for each possible linear combination result before making decisions. This preliminary action allows the decision module to simply look up the pre-computed compensation value rather than performing complex real-time calculations, thereby improving reception performance without significantly increasing operational complexity.
Solution Approach 2:
The patent computes and stores offset values that compensate for the non-centered alphabet bias in advance. These pre-computed offsets are then added to the linear combination results before decision-making, which corrects the bias and reduces bit error rates without adding complex real-time processing.
2Productivity
If the modulation alphabet is non-centered, then the data transmission efficiency is improved, but the equalization accuracy deteriorates due to induced bias
Solution Approach 1:
The patent converts the harmful bias effect caused by non-centered modulation alphabets into a beneficial correction mechanism. By computing and adding appropriate offset values to compensate for the non-centering, the system maintains the efficiency benefits of non-centered alphabets while eliminating their detrimental impact on detection accuracy.
Solution Approach 2:
The patent modifies the equalization process by introducing compensation parameters (offset values) that adjust the linear combination results. This parameter change allows the system to handle non-centered alphabets effectively, maintaining both transmission efficiency and detection accuracy by shifting the decision boundaries appropriately.
3Measurement precision
If decision thresholds are adapted to equalizer coefficients, then the symbol detection accuracy is improved, but the decision module complexity increases
Solution Approach 1:
The patent pre-computes decision thresholds based on the equalizer coefficients and stores them for direct use. This preliminary computation of thresholds eliminates the need for complex real-time threshold adaptation, maintaining high symbol detection accuracy while simplifying the operational complexity of the decision module.
Data Source
AI summary
The receiver includes a sampler designed to provide one or more samples (yn) per received symbol, the symbols belonging to a predefined alphabet; an equalizer designed to compute, for each received symbol, an estimate (zn) of this symbol based on a linear combination (y′n) of the samples (yn) for this symbol; and a decision module designed to determine the symbol of the alphabet closest to the estimate (zn) as detected symbol. The alphabet exhibits a decentering such that the transmitted symbols have a non-zero predefined expectation, and the equalizer is designed to add a non-zero scalar component (θ) to the linear combination (y′n) in order to compensate at least partially for the decentering.