Tunable Duobinary Transmitter Variable Delay
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Solution Overview
Problem
Duobinary signals perform poorly in well-dispersion-compensated systems and short transmission distances, where conventional binary signals excel, and vice versa, making it challenging to achieve optimal performance in both back-to-back and long-distance transmissions.
Innovation Solution
A method and apparatus that adjust the delay of a binary signal to produce a duobinary signal, allowing the delay to be either longer or shorter than one bit period, enabling improved back-to-back performance or dispersion tolerance depending on the transmission conditions, by incorporating a variable delay unit that can introduce fractional delays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional binary encoding is used, then back-to-back performance is improved, but dispersion tolerance deteriorates
Solution Approach 1:
The patent applies dynamics by making the delay parameter adjustable rather than fixed. The delay unit can be dynamically configured to provide different delay values (e.g., 0.5 bit periods for dispersion-tolerant mode or 1.5 bit periods for back-to-back mode), allowing the duobinary transmitter to adapt its characteristics based on transmission requirements.
Solution Approach 2:
The invention changes the delay parameter of the duobinary encoding process. By adjusting the delay value introduced to the binary signal before combining with the original signal, the transmitter can optimize performance for different transmission scenarios - shorter delays improve back-to-back performance while longer delays enhance dispersion tolerance.
2Object-affected harmful factors
If standard duobinary encoding with integer bit period delay is used, then dispersion tolerance is improved, but back-to-back performance deteriorates
Solution Approach 1:
The patent makes the delay parameter dynamic and adjustable. Instead of using a fixed integer multiple of bit periods, the delay unit can be configured to provide non-integer delays (e.g., 0.5, 1.5 bit periods), enabling the system to switch between dispersion-tolerant and back-to-back optimized modes as needed.
Solution Approach 2:
The invention changes the delay parameter from fixed integer bit periods to adjustable non-integer values. By modifying the delay value, the transmitter can achieve optimal balance between dispersion tolerance and back-to-back performance depending on the specific transmission conditions.
3Device complexity
If a single duobinary transmitter design is used, then device complexity is reduced, but adaptability to different transmission conditions deteriorates
Solution Approach 1:
The patent implements universality by designing a single duobinary transmitter that can perform multiple functions. The adjustable delay unit enables the same transmitter structure to optimize for both back-to-back transmission and long-distance dispersion-prone transmission by simply changing the delay parameter, eliminating the need for separate transmitter designs.
Solution Approach 2:
The invention adds dynamic capability to a unified transmitter structure. The delay unit can be adjusted based on transmission requirements, allowing one transmitter to adapt to different transmission conditions (short distance vs. long distance, well-compensated vs. un补偿ed channels) without requiring multiple specialized designs.
Data Source
AI summary
An apparatus and method for tunably delaying a signal and using that delayed signal in a duobinary transmitter is described. The transmitted duobinary signal is representative of the binary signal, and is formed by, among other things, introducing into a copy of the binary signal a delay that may be adjusted to be greater than or less than the bit period of the signal. Once the binary signal has been converted into a duobinary signal, it may then be converted into an optical duobinary signal. Alternatively, the conversion from binary to duobinary in accordance with the invention may be performed in the optical domain.