PON Transceiver Power Saving via Dynamic Sleep Modes

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Solution Overview

Problem

In PON systems, periodic measurement of round-trip times is necessary to prevent data collisions, but this leads to power wastage during low-bit-rate communication, especially when communication is intermittent, such as at night, and affects power consumption.

Innovation Solution

The system introduces a power saving mechanism where ONUs can enter a power saving mode, with the OLT controlling the power state of transceivers based on communication needs, allowing for reduced power consumption during idle periods by adjusting the power saving protocol according to ONU capabilities and communication conditions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If periodic measurement of round-trip times is performed to prevent data collisions, then communication reliability is improved, but power consumption increases

Engineering Contradiction:
Improvecommunication reliabilityVSAvoidpower consumption
Core Design Contradiction:
ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent applies periodic action by implementing cyclic sleep modes where the ONU periodically wakes up to perform round-trip time measurements and then returns to sleep state. This allows the system to maintain communication reliability through periodic measurements while significantly reducing power consumption by keeping the transceiver in a low-power state between measurements.

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The patent implements dynamics by making the transceiver state changeable between active and sleep modes based on communication conditions. The ONU can dynamically adjust its power consumption level by entering sleep mode when communication is not urgent and waking up when data transmission is needed, thus adapting the power usage to actual communication requirements.

Inventive Principle:
Principle #15Dynamics

2Speed

If transceiver remains in active state to maintain communication readiness, then communication responsiveness is improved, but power consumption increases

Engineering Contradiction:
Improvecommunication responsivenessVSAvoidpower consumption
Core Design Contradiction:
SpeedVSUse of energy by moving object

Solution Approach 1:

The patent uses periodic action by implementing scheduled wake-up intervals where the ONU wakes up at predetermined intervals to check for data and perform necessary measurements, then returns to sleep mode. This periodic activation maintains basic communication responsiveness while dramatically reducing power consumption compared to continuous operation.

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The ONU performs self-service by autonomously managing its own power state transitions based on buffer status and communication requirements. The ONU can independently determine when to wake up and when to sleep, and can autonomously transmit data when buffer overflow is detected without requiring constant OLT intervention, thus maintaining responsiveness while saving power.

Inventive Principle:
Principle #25Self-service

3Use of energy by moving object

If ONU enters power saving mode to reduce power consumption, then power efficiency is improved, but communication delay increases

Engineering Contradiction:
Improvepower efficiencyVSAvoidcommunication delay
Core Design Contradiction:
Use of energy by moving objectVSLoss of time

Solution Approach 1:

The patent applies partial action by implementing a hierarchical sleep mode structure with different wake-up intervals. Instead of a single sleep mode, the system provides multiple levels (e.g., doze mode with shorter intervals and sleep mode with longer intervals), allowing the ONU to select the appropriate depth of power saving based on communication urgency. This partial differentiation reduces excessive delays while maintaining power efficiency.

Inventive Principle:
Principle #16Partial or excessive action

Solution Approach 2:

The patent implements feedback mechanisms where the OLT monitors the ONU's buffer status and communication patterns, then provides feedback to adjust the sleep mode parameters. When the OLT detects that the ONU has accumulated data or communication is urgent, it can trigger the ONU to wake up earlier or increase measurement frequency, thus reducing delays while maintaining power efficiency during normal conditions.

Inventive Principle:
Principle #23Feedback

4Measurement precision

If round-trip time measurement is performed frequently to maintain synchronization, then timing accuracy is improved, but power consumption increases

Engineering Contradiction:
Improvetiming accuracyVSAvoidpower consumption
Core Design Contradiction:
Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The patent applies periodic action by scheduling round-trip time measurements at specific intervals rather than continuously. The ONU performs measurements only when waking up from sleep mode or when triggered by the OLT, reducing the frequency of measurements while maintaining adequate timing accuracy for the application requirements.

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The patent implements dynamics by making the measurement frequency adjustable based on communication conditions. During active communication periods, measurements are performed more frequently to maintain high timing accuracy, while during idle periods, the measurement interval is extended to reduce power consumption, thus dynamically adapting measurement precision to actual needs.

Inventive Principle:
Principle #15Dynamics

Data Source

PatentEP2955932B1Communication system, station-side optical line terminating apparatus, user-side optical line terminating apparatus, control apparatus, and communication method
Publication Date: 2021.05.26 MITSUBISHI ELECTRIC CORP
  • EP2955932B1 patent drawingFigure 1
  • EP2955932B1 patent drawingFigure 2
  • EP2955932B1 patent drawingFigure 3

AI summary

The present invention relates to a communication system in which a plurality of terminals are connected by a common line and a communication method and relates to, for example, a PON (Passive Optical Network) system including an OLT (Optical Line Terminal: a station-side terminating apparatus) and a plurality of ONUs (Optical Network Units: user-side terminating apparatuses).