Wavelength Selective Switches Mitigate Filter Impairments
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Solution Overview
Problem
Wavelength selective switches (WSSs) in WDM optical communication systems suffer from filter-based impairments, leading to bit error rate disparities across channels, which degrade network performance due to non-ideal pass-band filtering, resulting in unacceptable information loss and reduced signal quality.
Innovation Solution
Implementing a system with passive power splitters and WSSs to route power-split super-channels, combined with techniques such as comparative channel pre-emphasis, differentiated channel modulation formats, multi-channel forward error correction interleaving, differentiated channel baud rates, and selective subcarrier adjustments to mitigate filter-based impairments and equalize bit error rates across channels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If WSSs are used for routing optical signals in WDM systems, then signal routing flexibility is improved, but filter-based impairments cause bit error rate disparities across channels
Solution Approach 1:
The patent applies local quality by implementing channel-specific pre-emphasis adjustments where each optical channel receives customized equalization parameters. The system determines individual pre-emphasis values for each channel based on its specific attenuation characteristics, allowing localized optimization of signal quality for each wavelength while maintaining overall system flexibility.
Solution Approach 2:
The patent utilizes parameter changes by dynamically adjusting pre-emphasis parameters for different optical channels to compensate for filter-based impairments. The system modifies transmission parameters such as equalization coefficients and power levels on a per-channel basis, transforming the uniform routing approach into a differentiated parameter optimization strategy that addresses bit error rate disparities.
2Device complexity
If non-ideal pass-band filtering is applied in WSSs, then device complexity is reduced, but information loss increases due to filter-based impairments
Solution Approach 1:
The patent applies preliminary action by implementing pre-emphasis equalization before signals undergo pass-band filtering in the WSS. The system预先 adjusts the transmitted signal characteristics to anticipate and compensate for upcoming filter-induced distortions, thereby preventing information loss before it occurs rather than attempting correction after filtering.
Solution Approach 2:
The patent implements preliminary anti-action by applying pre-emphasis that introduces controlled signal modifications in advance to counteract the harmful effects of non-ideal filtering. This anticipatory compensation creates an opposing effect that neutralizes the filter-based impairments, reducing information loss while maintaining simple filter design.
3Productivity
If multiple optical signals are combined into super-channels for higher data rate transmission, then transmission capacity is improved, but filter-based impairments affect multiple channels simultaneously
Solution Approach 1:
The patent applies local quality by implementing channel-specific pre-emphasis adjustments within super-channels. Each optical channel that comprises part of a super-channel receives customized equalization parameters based on its specific attenuation characteristics, allowing localized optimization that addresses bit error rate disparities even when channels are multiplexed together for high-capacity transmission.
Solution Approach 2:
The patent utilizes segmentation by treating each optical channel within a super-channel as a separate entity requiring individual pre-emphasis optimization. The system divides the super-channel into constituent channels and applies differentiated pre-emphasis parameters to each segment, thereby addressing filter-based impairments on a per-channel basis while maintaining the aggregated high transmission capacity of the super-channel structure.
Data Source
AI summary
An apparatus may include a plurality of wavelength selective switches (WSSs). The apparatus may include a plurality of transmitters. The transmitters may transmit a plurality of super-channels. The apparatus may include a plurality of passive power splitters corresponding to the plurality of transmitters. The plurality of passive power splitters may receive the plurality of super-channels. The plurality of passive power splitters may generate a respective set of power-split super-channels for each super-channel of the plurality of super-channels. The plurality of passive power splitters may transmit each power-split super-channel of the respective set of power-split super-channels to a corresponding WSS of the plurality of WSSs. A WSS, of the plurality of WSSs, may receive a plurality of power-split super-channels, of the respective sets of power-split super-channels, from the plurality of passive power splitters. The WSS may selectively route a portion of the plurality of power-split super-channels toward a receiver.