ONU Variable Optical Attenuator for Downlink Signal Control
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Solution Overview
Problem
In passive optical networks (PON), the increase in single-wavelength modulation rate leads to decreased receiver sensitivity and a reduced link power budget, and adding an optical amplifier at the OLT side to boost transmission power risks damaging receivers due to varying attenuation levels among optical network units (ONUs).
Innovation Solution
Implementing variable optical attenuators at the ONU side to adjust downlink optical signal power within an optimal receiving range, and optionally integrating optical amplifiers at the ONU side to fine-tune power levels, ensuring consistent optimal reception.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If an optical amplifier is added at the OLT side to increase transmission optical power, then the link power budget is improved, but the receiving optical power of ONUs with maximum initial receiving power may exceed the damage threshold, resulting in damage to the optical receiver
Solution Approach 1:
The patent applies local quality by implementing individual variable optical attenuators at each ONU side rather than a uniform approach. Each ONU can independently adjust its received optical power level according to its specific attenuation characteristics and receiver requirements, allowing the system to maintain optimal power levels for each local receiver without affecting others
Solution Approach 2:
The patent implements dynamics by using variable optical attenuators that can dynamically adjust attenuation levels based on real-time monitoring of received optical power. The system continuously adapts the attenuation value to keep the received power within the optimal range, transforming a static fixed-gain amplification system into a dynamic controllable system
2Power
If a fixed gain amplification is applied to the downlink optical signal, then the transmission power is increased, but the receiving optical power cannot be controlled within the optimal range for all ONUs with different attenuation levels
Solution Approach 1:
The patent makes each ONU's receiving end adaptable to its specific attenuation characteristics by assigning individual variable optical attenuators. This allows each local receiver to optimize its own operating conditions rather than relying on a one-size-fits-all fixed gain approach from the OLT side
Solution Approach 2:
The patent implements feedback control by monitoring the received optical power at each ONU and using this information to adjust the variable optical attenuator settings. The system measures the actual received power and feeds this information back to control the attenuation, creating a closed-loop system that adapts to different attenuation levels automatically
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
Maintains optimal receiving power for optical receivers at ONUs, preventing damage and conserving energy by dynamically adjusting attenuator and amplifier settings based on monitored signal power.
Implementation Method 1
a variable optical attenuator is configured to adjust an attenuation value according to power of the downlink optical signal until the power of the downlink optical signal falls within a preset power range
Implementation Method 2
an optical amplifier (OA) may be added at an optical line terminal (OLT) side to increase transmission optical power of a transmitter
Data Source
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AI summary
The present disclosure provides a method and a device for controlling a downlink optical signal in a passive optical network, and a computer-readable storage medium. The method includes: monitoring power of a downlink optical signal in a process of receiving the downlink optical signal; and adjusting an attenuation value of a variable optical attenuator at an ONU side according to the power of the downlink optical signal until the power of the downlink optical signal falls within a preset power range. The variable optical attenuator at the ONU side is located between an optical splitter and an ONU. In the process of receiving the downlink optical signal by a receiver, if the power of the downlink optical signal is still out of the preset power range when the attenuation value of the variable optical attenuator is adjusted to a minimum value, a gain value of an OA at the ONU side is adjusted until the power of the downlink optical signal falls within the preset power range. The OA at the ONU side is located between the optical splitter and the ONU.