FDX Amplifier North-Port Interference Mitigation With Subband Filtering
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Solution Overview
Problem
Full duplex (FDX) amplifiers in broadband communications systems are prone to interference from various noise sources, which impair operations and throughput, particularly due to interference from upstream transmissions reaching the north port input, causing power fluctuations and affecting downstream signal quality and echo cancellation performance.
Innovation Solution
Implementing interference mitigation and cancellation methods, including resource block assignment scheduling, echo cancellation, and downstream path interference suppression using subband filtering and energy equalization, to reduce or eliminate interfering signals and improve signal-to-noise ratio and communication throughput.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If FDX amplifiers are used for simultaneous upstream and downstream transmissions, then communication throughput is improved, but interference from upstream transmissions degrades downstream signal quality
Solution Approach 1:
The patent segments the frequency spectrum into multiple subbands and applies different processing to each subband. Specifically, it divides the bandwidth into subbands, identifies those with upstream interference, and applies selective attenuation only to affected subbands while leaving clean subbands untouched. This segmentation approach allows simultaneous upstream and downstream transmissions to coexist by isolating interference to specific frequency portions.
Solution Approach 2:
The patent applies local quality by treating different subbands differently based on their interference characteristics. Instead of uniform processing across the entire bandwidth, it applies selective attenuation only to subbands containing upstream interference, while maintaining full gain for subbands without interference. This localized approach preserves downstream signal quality in clean subbands while mitigating interference in affected subbands.
2Productivity
If upstream transmission power is increased to improve upstream throughput, then upstream communication performance is improved, but power fluctuations at the north port degrade downstream amplifier performance
Solution Approach 1:
The patent performs preliminary action by detecting and mitigating upstream interference before it degrades downstream amplifier performance. The system continuously monitors subband energy levels, identifies upstream interference in advance, and applies attenuation proactively. This preliminary mitigation prevents power fluctuations from causing downstream performance degradation, allowing upstream power to be optimized without compromising downstream reliability.
Solution Approach 2:
The patent implements feedback by continuously monitoring subband energy levels at the amplifier input and using this information to dynamically adjust attenuation applied to each subband. The system measures the energy in each subband, compares it against thresholds to detect upstream interference, and automatically adjusts the attenuation level accordingly. This closed-loop feedback mechanism ensures downstream amplifier performance is maintained despite varying upstream transmission conditions.
3Object-affected harmful factors
If subband filtering and energy equalization are applied to suppress interference, then downstream signal quality is improved, but device complexity increases
Solution Approach 1:
The patent applies partial action by selectively processing only the subbands that contain upstream interference rather than applying uniform processing to the entire bandwidth. The system identifies specific subbands affected by interference and applies attenuation only to those subbands, leaving other subbands untouched. This partial processing approach achieves effective interference suppression while minimizing the computational complexity and processing overhead compared to full-bandwidth processing.
Data Source
AI summary
In some aspects, the disclosure is directed to methods and systems for interference mitigation and cancellation in full duplex amplifiers for cable modem or broadband communication systems. In many implementations, an interference canceller in the downstream path may be provided to equalize composite power on the FDX upstream subbands within a predetermined range of amplitude (e.g. X dB) from the desired downstream signal on the same subband, without affecting the downstream subbands.