Equalizer for Time-Varying Channels Using Preliminary Action
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Solution Overview
Problem
Current methods for equalizing data symbol sequences in time-varying transmission channels are computationally intensive and introduce additional interference, leading to errors in signal-to-noise ratio, especially when the channel impulse response changes during data symbol bursts.
Innovation Solution
The method iteratively calculates the path metric and channel impulse response estimates, reducing the number of required channel impulse response estimates and using recursive calculations to minimize computational effort and interference, allowing for real-time equalization with a reduced pulse length.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the number of channel impulse response estimates is reduced by shortening the impulse length of the transmission channel, then the computational complexity is reduced, but the manufacturing precision of the equalization estimate deteriorates
Solution Approach 1:
The patent applies preliminary action by performing a first channel impulse response estimate before the equalization process using a training sequence. This preliminary estimate is then used to generate a pre-filter that shortens the impulse length of the transmission channel. By preparing this preliminary estimate and pre-filter in advance, the system reduces the number of subsequent channel estimates needed during equalization, thereby reducing computational complexity while maintaining equalization precision through the use of the pre-computed preliminary estimate.
2Productivity
If the Viterbi algorithm is used to reduce the number of state combinations in the trellis diagram, then the productivity of data symbol estimation is improved, but the device complexity increases due to the need for multiple channel impulse response estimates
Solution Approach 1:
The patent performs a preliminary channel impulse response estimate before the Viterbi algorithm execution using a training sequence. This preliminary estimate is stored and reused during the Viterbi algorithm process, eliminating the need to perform new channel estimates for each state transition in the trellis diagram. This preliminary action significantly reduces the total number of channel estimates required, thereby reducing device complexity while maintaining the high productivity of the Viterbi algorithm for data symbol estimation.
3Manufacturing precision
If the impulse response length of the transmission channel is shortened using a pre-filter, then the manufacturing precision of the equalization is improved, but the device complexity increases due to additional filtering operations
Solution Approach 1:
The patent generates the pre-filter that shortens the impulse length as a preliminary action before the main equalization process. By computing this pre-filter once using the preliminary channel estimate and training sequence, the system avoids the need for complex real-time filtering operations during data symbol estimation. This preliminary generation of the pre-filter improves equalization precision while minimizing the increase in device complexity, as the filter is prepared in advance rather than being applied dynamically during processing.
Data Source
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AI summary
The invention relates to a method for equalising a data symbol sequence (r(k)) captured by a time-variable transmission channel. According to said method, at each point in time (k), the pulse response (h