Optical Channel FEC Layering With Low-State Trellis Coding
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Solution Overview
Problem
Complex FEC encoders and decoders in optical communication systems consume more power, which is a concern in applications where reducing power consumption is important without compromising performance.
Innovation Solution
An optical module with a second FEC encoder having a bit-level trellis representation with fewer than 64 states is used to further code a subset of the first FEC encoded data, reducing power consumption while maintaining performance by implementing an FEC code with low complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If complex FEC encoders and decoders are used to achieve greater performance, then data recovery performance is improved, but power consumption increases
Solution Approach 1:
The patent segments the FEC encoding process into two distinct stages: an outer FEC encoder (first encoder) that provides baseline error correction, and an inner FEC encoder (second encoder) that provides additional protection for critical data portions. This segmentation allows the system to achieve high reliability through layered protection while managing power consumption by using different encoder complexities for different data portions, rather than applying uniform complex encoding to all data.
Solution Approach 2:
The patent applies different encoding qualities to different portions of data. The inner FEC encoder with bit-level trellis representation (≤64 states) is applied selectively to a subset of encoded data that requires higher reliability, while other data portions use only the outer FEC encoding. This local quality approach ensures that power-intensive complex encoding is applied only where necessary to maintain performance.
2Use of energy by moving object
If low-complexity FEC encoders are used to reduce power consumption, then power usage is reduced, but data recovery performance deteriorates
Solution Approach 1:
The patent implements prior cushioning by applying outer FEC encoding first to all data, creating a baseline level of error protection. Then, inner FEC encoding is applied to additional subsets of this already-protected data, providing an extra layer of defense. This layered approach ensures that even if the low-complexity outer encoder is used, performance is maintained through the cumulative effect of multiple encoding layers.
Solution Approach 2:
The patent creates a composite FEC encoding scheme that combines two different encoding approaches: outer FEC encoding (which can be simpler) and inner FEC encoding with bit-level trellis representation (which provides enhanced protection). This composite approach merges the advantages of both encoding methods, achieving reliable data recovery while managing the complexity and power consumption of the overall system.
Data Source
AI summary
An optical module processes first FEC (Forward Error Correction) encoded data produced by a first FEC encoder. The optical module has a second FEC encoder for further coding a subset of the first FEC encoded data to produce second FEC encoded data. The optical module also has an optical modulator for modulating, based on a combination of the second FEC encoded data and a remaining portion of the first FEC encoded data that is not further coded, an optical signal for transmission over an optical channel. The second FEC encoder is an encoder for an FEC code that has a bit-level trellis representation with a number of states in any section of the bit-level trellis representation being less than or equal to 64 states. In this manner, the second FEC encoder has relatively low complexity (e.g. relatively low transistor count) that can reduce power consumption for the optical module.