Hybrid Precoder for Crosstalk Mitigation in Last-Mile Copper Links
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Solution Overview
Problem
Existing communication systems using twisted copper pairs for 'last-mile' telecommunications face significant challenges due to far-end crosstalk (FEXT), which adversely affects data bit rates and signal quality, especially at higher frequencies, where traditional linear precoding methods are insufficient.
Innovation Solution
A hybrid precoding system that dynamically switches between linear and non-linear precoding based on channel characteristics, employing orthogonal frequency-division multiplexing (OFDM) to determine the optimal precoding scheme for each subcarrier frequency, thereby minimizing FEXT and enhancing performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If linear precoding is used, then device complexity is reduced, but FEXT cancellation performance deteriorates at higher frequencies
Solution Approach 1:
The frequency spectrum is segmented into multiple subcarriers through OFDM modulation. Each subcarrier can be independently processed with appropriate precoding (linear or non-linear) based on channel conditions, allowing the system to achieve good FEXT cancellation performance where needed while maintaining lower complexity where possible.
Solution Approach 2:
The system dynamically selects between linear and non-linear precoding schemes based on channel characteristics and FEXT conditions. This dynamic adaptation allows the system to optimize performance in real-time, using non-linear precoding (e.g., THP) when FEXT is severe and linear precoding when conditions are more favorable.
2Reliability
If non-linear precoding is used, then FEXT cancellation performance is improved, but device complexity increases
Solution Approach 1:
Non-linear precoding is applied selectively to specific subcarriers or frequency bands where FEXT is most problematic, rather than uniformly across the entire spectrum. This local application of enhanced processing provides targeted FEXT cancellation where needed while avoiding unnecessary complexity in other regions.
Solution Approach 2:
The system changes processing parameters dynamically by switching between different precoding schemes (linear vs. non-linear) based on channel state information and FEXT measurements. This parameter adaptation allows optimization of the trade-off between performance and complexity.
3Productivity
If optical fiber is deployed closer to end-user, then data carrying capacity is improved, but deployment cost increases
Solution Approach 1:
The patent converts the harmful FEXT effect, which is an inherent limitation of copper pairs, into a manageable parameter through sophisticated precoding techniques. By actively canceling FEXT using channel state information and appropriate precoding schemes, the system achieves high data rates over copper infrastructure, thereby avoiding the need for expensive fiber deployment while maintaining high productivity.
Data Source
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AI summary
A method employing linear preceding and non-linear precoding for transmitting data between at least two transmitters and a plurality of receivers via a plurality of communication channels over a plurality of subcarrier frequencies, the method comprising the procedures of transmitting by either one of said at least two transmitters, at least two training signals to respective said receivers; receiving by respective said receivers, said at least two training signals; evaluating channel characteristics of at least part of said communication channels, according to said at least two training signals; determining a precoding scheme selection that defines for at least part of said communication channels, over which of said subcarrier frequencies, said data transmitted shall be preceded using either one of linear precoding and non-linear precoding, according to evaluated said channel characteristics; precoding said data according to determined said precoding scheme selection; and transmitting said data according said precoding scheme selection.