Partial FEXT Cancellation via Dynamic Programming Resource Allocation
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Solution Overview
Problem
Current digital subscriber line (xDSL) systems face inefficiencies in mitigating far-end cross-talk (FEXT) due to high computational and memory requirements, leading to suboptimal performance and increased costs, particularly in VDSL systems where full FEXT cancellation is computationally infeasible with current processor technology.
Innovation Solution
A method and system for partial FEXT cancellation using dynamic programming to selectively allocate resources by calculating and sorting normalized disturber coupling values and SNR function values, allowing for efficient allocation of computational resources to maximize the weighted rate of users, thereby optimizing crosstalk cancellation within limited computational and power constraints.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If full FEXT cancellation is implemented in VDSL systems, then crosstalk mitigation performance is improved, but computational resource requirements become prohibitively high
Solution Approach 1:
The patent implements partial FEXT cancellation by selectively cancelling crosstalk only for victim users who meet specific criteria (such as having crosstalk above a threshold level or being in specific service classes) rather than attempting to cancel crosstalk for all users. This partial approach achieves significant performance improvement for the most affected users while keeping computational requirements manageable.
Solution Approach 2:
The patent applies different cancellation strategies to different users based on their specific conditions. Victim users are categorized into different classes (e.g., Class 1, Class 2, Class 3) with different service requirements and crosstalk thresholds. Each class receives appropriate cancellation resources, ensuring that users with higher crosstalk interference or stricter service requirements receive priority treatment while less affected users receive minimal or no cancellation, optimizing overall system performance within computational constraints.
2Reliability
If FEXT cancellation resources are increased, then crosstalk cancellation performance is improved, but power consumption increases
Solution Approach 1:
The system performs partial FEXT cancellation only for selected victim users rather than all users, significantly reducing the total computational workload and associated power consumption while still achieving acceptable performance for the most affected users.
Solution Approach 2:
The patent dynamically adjusts cancellation parameters such as the number of disturbers to cancel, the set of tones processed, and the service class thresholds based on system conditions and available resources. This allows the system to optimize the balance between performance and power consumption by adapting to changing conditions rather than operating at fixed resource levels.
3Productivity
If computational resources are allocated to maximize performance for all users, then overall system performance is improved, but resource allocation complexity increases
Solution Approach 1:
The patent divides users into different service classes with different requirements and allocates resources accordingly. Class 1 users (with stricter requirements) receive priority cancellation resources while Class 3 users (with more relaxed requirements) receive minimal resources. This differentiated approach simplifies the allocation problem by creating clear priority levels rather than attempting to optimize for all users simultaneously with equal resources.
Solution Approach 2:
The patent segments the user population into different classes based on service requirements and crosstalk susceptibility. This segmentation allows the system to handle resource allocation in discrete, manageable groups rather than as a single complex optimization problem, reducing computational complexity while maintaining overall system performance.
4Productivity
If FEXT cancellation is performed for more users, then number of satisfied users increases, but memory usage and computational overhead increase
Solution Approach 1:
The system performs FEXT cancellation for a selective subset of victim users rather than all users, identifying and serving the most affected users first. This partial approach increases the number of satisfied users to a practical level while avoiding the exponential growth in memory and computational requirements that would result from serving all users.
Data Source
AI summary
A method implemented in a multi-user communication system is described for performing far-end crosstalk (FEXT) cancellation for each victim user. The method comprises performing dynamic programming to allocate resources according to (N−1) normalized disturber coupling values and difference rate function values associated with N total users in the system involved in partial FEXT cancellation. In accordance with some embodiments, dynamic programming comprises selecting a tone and one or more disturbers to be cancelled for the tone.