Frequency Domain Cancellation of ADSL Side Lobes
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Solution Overview
Problem
ADSL deployment in regions with existing TCM-ISDN telephone lines faces severe performance limitations due to noise and interference, necessitating a more efficient method to reduce residual interference caused by disturber tones.
Innovation Solution
Implementing frequency domain methods that calculate and apply optimal loads to 'canceller tones' as a linear combination of disturber tones to minimize the impact of aggregate side lobes on victim frequencies, using an aggregate power module and optimal load module to determine and apply these loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If ADSL deployment is implemented in regions with existing TCM-ISDN telephone lines, then high bandwidth data transmission can be provided, but severe performance limitations occur due to noise and interference from disturber tones
Solution Approach 1:
The patent applies the principle of converting harm into benefit by using the disturber tones themselves as the basis for generating canceller tones. The harmful interference signals are captured and transformed into useful cancellation signals that actively counteract the original interference, thereby converting the harmful disturber tones into beneficial cancellation resources.
Solution Approach 2:
The patent introduces canceller tones as intermediary elements between the disturber tones and the victim tones. These canceller tones act as mediators that process the interference information and generate appropriate cancellation signals, serving as an intermediate mechanism to resolve the interference problem without directly eliminating the disturber tones.
2Object-affected harmful factors
If frequency domain methods with canceller tones are applied to reduce side lobes, then interference impact is reduced by 5-6 dB, but system complexity increases due to calculation and optimization requirements
Solution Approach 1:
The patent applies preliminary action by pre-calculating and pre-optimizing the canceller tone loads based on the disturber tone characteristics. The optimal loads are determined in advance through calculation and optimization processes, allowing the system to be prepared and configured before actual interference occurs, thereby reducing real-time computational complexity.
Solution Approach 2:
The patent utilizes parameter changes by adjusting and optimizing the load parameters of the canceller tones. By varying and fine-tuning these load parameters to minimize aggregate side lobes, the system achieves effective interference cancellation. This parameter optimization approach allows for flexible adaptation to different interference conditions while managing system complexity through automated adjustment.
Data Source
AI summary
The present invention is directed to implementing theoretical foundations of frequency domain methods aiming to locally decrease the impact of aggregate side lobes of a few discrete frequency tones, in the vicinity of other “victim” frequencies. The family of frequency methods referred to makes use of one or more “canceller tones.” The “canceller tones” loads are optimized to minimize the aggregate power in the neighborhood of the victim frequencies. An exemplary method for decreasing an impact of aggregate side lobes of one or more discrete frequency tones in the vicinity of one or more victim tones comprises the steps of calculating an aggregate power of one or more side lobes of one or more disturber tones within a victim bandwidth; determining at least one optimal load to minimize the aggregate power wherein the at least one optimal load comprises a linear combination of the one or more disturber tones; and applying the at least one optimal load to one or more canceller tones for minimizing the impact of the one or more side lobes of the one or more disturber tones.