PON Optical Transmission Modulation Adaptation
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Solution Overview
Problem
Existing optical transmission systems face challenges in avoiding wavelength dispersion, requiring separate dispersion compensators for different transmission distances and expensive digital signal processing, which increases operational costs, especially in Point-to-MultiPoint (PtMP) network topologies like PON, where multiple dispersion compensators are needed due to varying distances between OLT and ONUs.
Innovation Solution
An optical transmission system that uses a control means to determine whether to perform intensity modulation or phase modulation on optical signals based on transmission distances and modulation bands, allowing one of the modulation signals to be transmitted to each receiving station, thereby eliminating the need for dispersion compensators and reducing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If dispersion compensation fiber is physically inserted to compensate for wavelength dispersion, then wavelength dispersion is compensated, but operational cost increases
Solution Approach 1:
The patent replaces the mechanical/optical system of physically inserting dispersion compensation fibers with an electrical/digital system. Specifically, it uses digital signal processing (DSP) algorithms to compensate for wavelength dispersion in the electrical domain after optical-to-electrical conversion, thereby eliminating the need for physical dispersion compensation fibers and reducing operational costs while maintaining dispersion compensation effectiveness
Solution Approach 2:
The patent changes the approach from optical domain parameter adjustment (physical fiber insertion) to electrical domain parameter processing (digital signal manipulation). By transforming the dispersion compensation function into the electrical domain through ADC conversion and applying digital filtering algorithms, the system achieves the same compensation effect without the cost and complexity of multiple physical dispersion compensation fibers
2Reliability
If digital signal processing is used to compensate for wavelength dispersion, then wavelength dispersion is compensated, but apparatus cost increases
Solution Approach 1:
The patent makes the receiving station apparatus universal by equipping it with both optical-to-electrical conversion capability and digital signal processing functionality. This allows the same apparatus to handle both short-distance and long-distance transmissions by dynamically adjusting DSP parameters, eliminating the need for separate dispersion compensation fibers for different distances and reducing overall system complexity and cost
Solution Approach 2:
The patent introduces dynamic adaptability through configurable DSP parameters that can be adjusted based on transmission distance and channel conditions. The receiving station can dynamically switch between different compensation algorithms and parameter settings, making a single apparatus suitable for multiple transmission scenarios without requiring multiple fixed-configuration devices
3Reliability
If multiple dispersion compensation fibers are installed for different routes in PtMP network, then wavelength dispersion is compensated for each ONU, but device complexity and cost increase
Solution Approach 1:
The patent uses digital copies of compensation algorithms instead of physical copies of dispersion compensation fibers. The same DSP compensation algorithm and parameter set can be replicated and applied to multiple ONUs through the optical network, allowing a single apparatus design to serve multiple transmission distances without requiring physical duplication of compensation components for each route
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively avoids wavelength dispersion using a simple configuration, ensuring constant signal quality across all receiving stations without the need for additional dispersion compensators, thereby reducing operational costs and improving user throughput in PON systems.
Implementation Method 1
intensity modulation means for performing intensity modulation on an optical signal
Implementation Method 2
phase modulation means for performing phase modulation on an optical signal
Data Source
Figure 1A
Figure 1B
Figure 2
AI summary
An optical transmission system in which a transmitting station and a plurality of receiving stations are connected via an optical splitter, the optical transmission system being for realizing optical fiber transmission, wherein the transmission station includes: control means for determining, in the transmitting station, whether to perform intensity modulation or phase modulation on optical signals based on information on transmission distances to the receiving stations and modulation bands; intensity modulation means for performing intensity modulation on an optical signal; and phase modulation means for performing phase modulation on an optical signal, and wherein one of an intensity modulation signal and a phase modulation signal is transmitted from the transmitting station to each of the receiving stations.