DMT MIMO Crosstalk Cancellation Using Decision-Directed Filtering
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Solution Overview
Problem
Current adaptive filtering techniques are inadequate in effectively eliminating crosstalk and noise from signals in telecommunication systems, particularly due to unknown initial parameters and changing channel characteristics, leading to incomplete interference cancellation and potential enhancement of additive noise.
Innovation Solution
A Multiple Input, Multiple Output (MIMO) system with receivers that exchange information to cancel in-domain crosstalk by using adaptive coefficients and decision symbols to generate cancellation signals, which are updated using least mean squares algorithms to improve signal quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If adaptive filtering techniques are used to eliminate crosstalk, then signal quality is improved, but additive noise is enhanced (increased)
Solution Approach 1:
The patent segments the crosstalk cancellation process into multiple independent filters, each handling a specific interferer source. This allows selective cancellation of crosstalk from different lines without collectively amplifying noise, as each filter operates independently with its own coefficient adaptation.
Solution Approach 2:
The patent introduces an intermediary signal processing stage that separates the estimation of crosstalk parameters from the cancellation operation. By using intermediate variables and staged processing, the system can cancel interference while controlling noise enhancement through careful management of the cancellation coefficients.
2Measurement precision
If complex mathematical operations are performed to determine channel characteristics, then measurement precision is improved, but computational complexity increases
Solution Approach 1:
The patent implements dynamic coefficient adaptation where filter coefficients are continuously updated based on incoming signals rather than requiring complete channel characterization upfront. This allows the system to track changing channel conditions with simpler incremental computations instead of complex batch processing.
Solution Approach 2:
The patent changes the parameter representation from complete channel impulse responses to simplified filter coefficients that capture the essential crosstalk characteristics. This parameter transformation reduces computational complexity while maintaining sufficient accuracy for practical crosstalk cancellation.
3Object-affected harmful factors
If filtering architecture is designed to reduce crosstalk from some sources, then crosstalk cancellation is improved, but additive noise from other sources is enhanced
Solution Approach 1:
The patent divides the crosstalk cancellation into multiple independent filter branches, each targeting a specific interferer source. This segmentation allows the system to optimize cancellation for each source independently while controlling the overall noise impact through coordinated coefficient adaptation across all branches.
Data Source
AI summary
The present disclosure generally pertains to systems and methods for cancelling crosstalk. A multiple input, multiple output (MIMO) system in accordance with one exemplary embodiment of the present disclosure has a plurality of receivers, which are capable of exchanging information with one another. Each receiver is coupled to a respective subscriber line and receives signals from a remote transmitter. In each path of the MIMO system, in domain crosstalk and possibly some combination of noise, alien crosstalk, and/or other interference such as RF interference, is canceled from the signal being processed. In some cases, a cancellation signal for cancelling crosstalk is based on an output of a symbol decision element, such as a slicer or decoder, thereby improving the accuracy of the cancellation signal.