Station-Side Optical Network Unit With SNR-Based Power Control
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Solution Overview
Problem
In PON systems, optical loss between the OLT and each ONU varies, leading to differing SNR for each ONU, resulting in wasted signal powers and limitations on transmission distance and power budget.
Innovation Solution
A station-side optical network unit that acquires SNR from subscriber-side ONUs, derives a quality indicator, and sets signal power to a minimum level ensuring a predetermined quality, with ONUs measuring and transmitting SNR to adjust power accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the OLT generates a downlink signal using one light source in a PON system, then the system structure is simple and cost-effective, but the SNR of received signals varies for each ONU causing power waste and limiting transmission distance
Solution Approach 1:
The patent applies local quality by enabling each ONU to receive customized signal power levels according to its specific SNR conditions. The OLT adjusts the power of downlink signals individually for each ONU based on measured SNR values, so that each ONU receives the optimal power level rather than a uniform power level for all users. This resolves the contradiction by maintaining system simplicity while eliminating power waste through localized power optimization.
Solution Approach 2:
The patent changes the power parameter of downlink signals dynamically based on SNR measurements. The OLT measures SNR for each ONU and adjusts the signal power parameter accordingly, transforming a static power transmission system into a dynamic one that adapts to varying channel conditions. This parameter change enables power optimization without complicating the basic PON architecture.
2Device complexity
If the OLT uses a single light source for downlink signal generation, then the device complexity is low, but the transmission distance is limited due to varying optical loss across branches
Solution Approach 1:
The patent applies local quality by enabling each ONU to receive customized signal power levels according to its specific SNR conditions. The OLT adjusts the power of downlink signals individually for each ONU based on measured SNR values, so that each ONU receives the optimal power level rather than a uniform power level for all users. This resolves the contradiction by maintaining system simplicity while eliminating power waste through localized power optimization.
Solution Approach 2:
The patent implements feedback by having ONUs measure their received SNR values and report back to the OLT. The OLT uses this feedback information to adjust the downlink signal power for each ONU, creating a closed-loop control system. This feedback mechanism enables the system to compensate for varying optical loss and extend transmission distance without increasing device complexity.
3Device complexity
If uniform power is transmitted to all ONUs, then the power control mechanism is simple, but power is wasted in ONUs with higher SNR while the system must be designed for the ONU with the lowest SNR
Solution Approach 1:
The patent applies local quality by enabling each ONU to receive customized signal power levels according to its specific SNR conditions. The OLT adjusts the power of downlink signals individually for each ONU based on measured SNR values, so that each ONU receives the optimal power level rather than a uniform power level for all users. This resolves the contradiction by maintaining system simplicity while eliminating power waste through localized power optimization.
Solution Approach 2:
The patent transforms the static uniform power transmission approach into a dynamic power control system. The OLT continuously measures SNR for each ONU and adjusts the downlink signal power in real-time based on current channel conditions. This dynamic adjustment allows the system to optimize power utilization efficiency while maintaining relatively simple control mechanisms through automated SNR-based power adaptation.
Data Source
AI summary
An aspect of the present invention is a station-side optical network unit to be connected to a subscriber-side optical network unit, the station-side optical network unit including: an acquisition unit that acquires, from the subscriber-side optical network unit, a signal-to-noise ratio of a received signal transmitted from the station-side optical network unit and received by the subscriber-side optical network unit; a deriving unit that derives a physical quantity indicating a quality of the received signal from the signal-to-noise ratio acquired by the acquisition unit; and a setting unit that sets a power of a signal transmitted by the station-side optical network unit to a minimum power among powers at which the physical quantity derived by the deriving unit indicates a predetermined quality.