PON OLT Message Queue Flow Control

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Solution Overview

Problem

In large-scale Passive Optical Network (PON) deployments, Optical Line Terminal (OLT) devices face performance degradation due to overwhelming alarm and Attribute Value Change (AVC) messages from Optical Network Units/Terminals (ONU/Ts), with existing solutions like Alarm Report Control (ARC) being inadequate for handling concurrent faults across multiple devices.

Innovation Solution

The OLT device temporarily stores alarm and AVC messages in a queue and generates flow control messages to instruct ONU/T devices to stop transmitting messages when a threshold is exceeded, with the option to resume transmission once the message queue falls below a second threshold, using a processing circuitry to manage the flow control messages and timing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the OLT device receives and handles alarm and AVC messages from a large number of ONU/T devices in a centralized manner, then the network monitoring capability is maintained, but the performance of the OLT device degrades due to overwhelming concurrent messages

Engineering Contradiction:
Improvenetwork monitoring capabilityVSAvoidOLT device performance
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent introduces a message queue as an intermediary component between the message reception interface and the centralized handling process. The queue buffers incoming alarm and AVC messages, decoupling the reception rate from the processing rate. This allows the OLT to maintain reliable network monitoring by queuing messages while preventing performance degradation by controlling the processing throughput.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent implements preliminary actions by pre-allocating a message queue with sufficient buffer capacity to handle expected message bursts. The queue is prepared in advance to absorb concurrent message floods from multiple ONU/T devices, allowing the OLT to maintain stability during fault conditions without immediate performance degradation.

Inventive Principle:
Principle #10Preliminary action

2Productivity

If rate limit or bandwidth control is applied to upstream data traffic from ONU/T devices, then single device message floods are controlled, but large scale faults across multiple devices cannot be effectively managed

Engineering Contradiction:
Improvemessage flood controlVSAvoidlarge scale fault handling capability
Core Design Contradiction:
ProductivityVSAdaptability or versatility

Solution Approach 1:

The patent merges the flow control functionality into the centralized message handling architecture at the OLT. Instead of implementing separate rate limits at each ONU/T device, the control mechanism is unified at the OLT where it can monitor and regulate messages from all devices collectively. This allows effective handling of both single-device and large-scale faults through a single coordinated control point.

Inventive Principle:
Principle #5Merging (Combining)

Data Source

PatentEP2865109B1Devices and methods for flow control of messages in an passive optical network (PON) and methods therein
Publication Date: 2018.06.06 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)
  • EP2865109B1 patent drawingFigure 1
  • EP2865109B1 patent drawingFigure 2
  • EP2865109B1 patent drawingFigure 3~4

AI summary

A method in an Optical Line Terminal, OLT, device (110) for transmitting a flow control message to an Optical Network Unit/Terminal, ONU/T, device (130; 140) in a Passive Optical Network, PON, access network (100) is provided. The OLT device (110) is configured to receive alarm and/or Attribute Value Change, AVC, messages from the ONU/T device (130; 140). The OLT device (110) is also configured to temporarily store the alarm and/or AVC messages in a message queue. The OLT device (110) generates a flow control message indicating that the ONU/T device (130; 140) is to stop transmitting alarm and/or AVC messages to the OLT device (110), when the number of alarm and/or AVC messages in the message queue exceeds a first threshold. Then, the OLT device (110) transmits the flow control message to the ONU/T device(s) (130; 140). An OLT device (110) for transmitting a flow control message to a ONU/T device (130; 140), an ONU/T device (130; 140) for receiving a flow control message, and method in an ONU/T device (130; 140) for receiving a flow control message is also provided.