Optical Modulation for PON Signal Quality and Cost Reduction
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Solution Overview
Problem
In PON systems, high transmission rates lead to poor digital signal quality and high implementation costs due to the use of up-conversion processing technology, which results in signal distortion and increased costs.
Innovation Solution
The method involves splitting a digital signal into two signals, converting them into analog in-phase and quadrature signals, modulating these signals into orthogonal polarization states, and combining them into a single optical signal for transmission, eliminating the need for up-conversion processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If up-conversion processing technology is used to achieve high transmission rates, then transmission rate is improved, but digital signal quality deteriorates due to signal distortion
Solution Approach 1:
The patent changes the modulation scheme from up-conversion to direct modulation of laser diodes at high rates. By using advanced modulation formats (such as PAM4, NRZ) and optimizing electrical parameters (current, voltage, bandwidth) of the laser diodes and transimpedance amplifiers, the system achieves high transmission rates without the signal distortion introduced by up-conversion processing, thereby maintaining digital signal quality
Solution Approach 2:
The patent extracts and eliminates the up-conversion processing stage from the optical transmission system. By directly modulating the laser diodes with the high-rate digital signals and using high-bandwidth photodetectors for direct detection, the system removes the intermediate frequency conversion steps that cause signal distortion, thus improving digital signal quality while maintaining high transmission rates
2Speed
If up-conversion processing technology is used to achieve high transmission rates, then transmission rate is improved, but implementation costs increase due to expensive processing devices
Solution Approach 1:
The patent extracts and eliminates the complex up-conversion processing devices (modulators, mixers, local oscillators) from the system architecture. By using direct modulation of laser diodes and direct detection with photodetectors, the system replaces expensive analog processing equipment with simpler, more cost-effective electronic components that can be integrated into standard optical transceivers
Solution Approach 2:
The patent employs cost-effective laser diodes and photodetectors that can operate directly at high rates without requiring expensive up-conversion infrastructure. By using commercially available high-speed optical components and simplified modulation/detection schemes, the system achieves high transmission rates with lower implementation costs compared to up-conversion systems
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 improves signal quality by avoiding signal distortion and reduces costs by eliminating the need for expensive up-conversion processing devices.
Implementation Method 1
respectively modulating the analog in-phase signal and the analog quadrature signal to two optical signals that are perpendicular to each other and are in a polarization state
Implementation Method 2
two optical signals that are perpendicular to each other and are in a polarization state
Data Source
AI summary
The present invention relates to the field of mobile communications technologies. The methods for sending and receiving a signal are specifically: splitting a received digital signal into a first digital signal and a second digital signal, respectively converting the first digital signal and the second digital signal into an analog in-phase signal and an analog quadrature signal, respectively modulating the analog in-phase signal and the analog quadrature signal to two optical signals that are perpendicular to each other and are in a polarization state, combining, into one optical signal, the two optical signals that are perpendicular to each other and are in a polarization state, and sending the optical signal to an ONU; and performing, by the ONU, corresponding demodulation on the optical signal, and sending the optical signal to a user terminal.