FDM DMT Repeater Power Spectral Density Shaping
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Solution Overview
Problem
The deployment of repeaters in DSL networks is limited due to their potential for generating significant spectral interference, particularly the 'near-far' interference problem, which restricts the use of high-speed data services and requires excessive copper pairs, making it impractical and expensive to achieve high bitrates.
Innovation Solution
The method involves computing the level of far-end cross-talk interference and modifying the power spectral density (PSD) shape for FDM DMT repeaters to minimize interference, allowing for higher bitrates per copper pair while reducing spectral impact on residential DSL services by optimizing repeater placement and PSD shaping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If traditional repeaters are deployed to extend DSL service reach, then the service coverage distance is improved, but spectral interference and cross-talk increase significantly
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the power spectral density (PSD) parameters of the repeater transmitter across different frequency bins. The system modifies transmit power levels in each frequency bin based on measured cross-talk conditions, transforming the fixed-parameter traditional repeater into an adaptive system that optimizes spectral distribution to minimize interference while maintaining service reach extension.
2Power
If repeater transmit power is increased to improve signal strength, then the signal coverage is improved, but cross-talk interference to neighboring copper pairs increases
Solution Approach 1:
The patent implements local quality by applying different power spectral density characteristics to different frequency bins rather than using a uniform power spectrum. The system identifies specific frequency ranges where cross-talk is problematic and applies targeted power reduction in those bins while maintaining or increasing power in other bins, creating a non-uniform spectral profile that locally optimizes the signal-to-interference ratio for each frequency band.
Solution Approach 2:
The system applies partial action by selectively adjusting power levels in only those frequency bins where cross-talk interference is measured to be problematic, rather than uniformly reducing power across the entire spectrum. This allows the repeater to maintain high signal strength in clean frequency bins while applying interference mitigation only where necessary, achieving partial optimization rather than global reduction.
3Productivity
If multiple copper pairs are bonded to achieve high bitrates, then the data rate is improved, but the cost and complexity of deployment increases
Solution Approach 1:
The patent employs copying by having the repeater create a spectral profile copy of the received signal characteristics and apply this profile to shape the transmitted signal. The system measures the spectral characteristics of incoming signals from multiple copper pairs and uses this information to construct an optimized transmit spectrum that accounts for the combined signal characteristics, effectively copying and adapting the received spectral pattern for retransmission.
Data Source
AI summary
A system and method for providing a service over a repeatered link that couples a service provider transceiver to a remote modem, the method includes: computing, for each frequency bin out of multiple frequency bins of a spectrum, a level of far-end cross-talk (FEXT) interference that is generated to a network-side receiver of a frequency division multiplexing (FDM) discrete multi tone (DMT) repeater by a service provider transmitter that provides an FDM DMT service that is supported by the FDM DMT repeater; computing, for each frequency bins out of the multiple frequency bins, a highest allowable transmit power level of a customer-side transmitter of the FDM DMT repeater that generates to the network-side receiver of the FDM DMT repeater a cross-talk interference that does not exceed a level of FEXT interference that is generated to the network-side receiver of the FDM DMT repeater by the service provider transmitter.