Tapped Delay Line Equalizer Tap Selection for Long Delay Spread
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Solution Overview
Problem
Existing equalizers, such as decision-feedback equalizers (DFE), face inefficiencies when dealing with channels that have long delay spread, requiring more computations and hardware to achieve accurate performance, especially in long delay spread channels where pre-echoes and post-echoes are spread over a relatively long period.
Innovation Solution
The configuration of equalization circuitry involves selecting significant taps from feedforward and feedback filter circuitry, where each selected tap has a magnitude greater than or equal to other taps, and adding taps to the feedback circuitry, using algorithms like LMS and Cholesky factorization to adapt and compute optimal tap values, thereby reducing computational complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a decision-feedback equalizer (DFE) is used to equalize channels with long delay spread, then accurate performance can be achieved, but computational complexity and hardware requirements increase significantly
Solution Approach 1:
The patent extracts and processes only the most significant taps from the channel impulse response based on magnitude thresholding. By identifying and retaining only taps whose magnitudes exceed a predetermined threshold, the system eliminates the need to process all taps, thereby reducing computational complexity while maintaining equalization accuracy for long delay spread channels.
Solution Approach 2:
The patent applies different processing strategies to different portions of the channel impulse response. Significant taps (those exceeding the threshold) are processed with full precision using DFE algorithms, while insignificant taps are either truncated or processed with reduced precision. This localized quality approach ensures accurate processing where needed while reducing overall computational burden.
2Reliability
If more taps are processed in the feedforward filter to capture long delay spread echoes, then equalization performance improves, but the number of computations and hardware resources required increase
Solution Approach 1:
The patent extracts only the significant portion of the channel impulse response by applying a magnitude threshold to identify important taps. This extraction process allows the system to focus computational resources on processing only those taps that contribute meaningfully to equalization performance, thereby improving computational efficiency without sacrificing reliability.
Solution Approach 2:
Instead of processing all taps in the channel impulse response, the patent applies partial action by processing only the significant taps that exceed a predetermined threshold. This partial processing approach achieves sufficient equalization performance for long delay spread channels while avoiding the excessive computational burden of processing every tap.
Data Source
AI summary
Methods and apparatus are provided for performing equalization of communication channels. In an embodiment of the invention, at least one tap can be selected from a set of feedforward taps of feedforward filter circuitry, where each tap of the selected at least one tap has a magnitude that is greater than or substantially equal to a magnitude of any tap of the set of feedforward taps that is not in the selected at least one tap. In addition, at least one tap can be added to a set of taps of feedback filter circuitry in communication with the feedforward filter circuitry. The invention advantageously allows for more efficient and reliable equalization of communication channels.