Optical Super-Channel Coding That Turns ICI Into Decodable Data
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Solution Overview
Problem
Coherent optical communications face challenges in transmitting data over optical super-channels due to inter-channel interference (ICI), which is treated as noise, leading to reduced transmission rates and increased noise levels, especially at high data rates greater than 100 Gbit/s.
Innovation Solution
The approach involves jointly decoding data from neighboring sub-channels with lower noise, shaping the ICI spectrum to increase decodable power, and using dirty-paper coding for interference alignment, along with adaptive coding rates and power arrangements to maximize reliability and data rates, rather than filtering to reduce ICI.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional filtering (e.g., root-raised-cosine filter) is used to minimize inter-channel interference, then ICI is reduced, but transmission rate is reduced due to suppression of data in the transmitted signal
Solution Approach 1:
The patent converts the harmful ICI into a beneficial resource by treating it as usable data. Instead of filtering out ICI as conventional systems do, the invention jointly decodes data from multiple sub-channels including the ICI components, thereby transforming the interference into additional decodable data that increases overall transmission rate while maintaining reliability
Solution Approach 2:
The patent merges the decoding of multiple sub-channels into a joint decoding process. By combining the data streams from neighboring sub-channels and treating ICI as part of the decodable signal, the system achieves higher effective transmission rates without sacrificing error performance
2Ease of operation
If the gap between frequencies of different sub-channels is decreased to operate as a single wideband channel, then routing and adding/dropping efficiency is improved, but inter-channel interference increases
Solution Approach 1:
The patent converts the harmful ICI resulting from small frequency gaps into a beneficial resource. By implementing joint decoding that treats ICI as usable data from neighboring sub-channels, the system can maintain small frequency gaps for efficient routing while transforming the resulting interference into additional decodable data streams
Solution Approach 2:
Instead of trying to eliminate ICI through filtering as conventional systems do, the patent inverts the approach by embracing ICI and treating it as useful data. The joint decoding process explicitly incorporates ICI components from adjacent sub-channels, turning the traditional problem into a solution
3Productivity
If serial ADC sampling rates are increased for single-wavelength coherent detection, then data rate is improved, but implementation difficulty increases for data rates greater than 100 Gbit/s
Solution Approach 1:
The patent segments the high-rate data transmission into multiple parallel sub-channels, each operating at lower data rates that are feasible for existing ADC components. By dividing the total data rate across multiple wavelengths rather than using a single high-speed ADC, the system achieves >100 Gbit/s transmission using commercially available ADC technology
Solution Approach 2:
The patent transitions from single-wavelength detection to multi-wavelength super-channel transmission, adding the wavelength dimension to the data transmission. This allows the system to achieve high aggregate data rates by parallelizing across multiple wavelengths, each processed by moderate-speed ADCs
Data Source
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AI summary
The transmission of data from a transmitter to a receiver over an optical super-channel including a set of sub-channels of different frequencies includes partitioning the data into a set of data streams including one data stream for each sub-channel and partitioning each data stream into a set of sub-streams. Each sub-stream of each data stream is encoded with different forward error correction (FEC) codes to produce a set of encoded sub-streams for each data stream, and the set of encoded sub-streams of each data stream are superimposed with different powers to produce a set of encoded data streams. The set of encoded data streams is multiplexed to produce an optical signal transmitted over the set of sub-channels of the optical super-channel.