Optical Node Latency Reduction via Advanced Time Slot Control

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Solution Overview

Problem

Existing optical transmission networks face increased complexity and latency due to the need for precise fiber delay line adjustments and the propagation time introduced by delay elements, which complicates the alignment process and increases network latency.

Innovation Solution

The optical node design structures data and control channels into equidistant timeslots, where the control packet headers are carried one or more time slots ahead of the data packets, allowing the controller to process and disassemble data packets without requiring delay elements, thus reducing network latency and eliminating the need for complex fiber delay line adjustments.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If delay elements are used to allow controller processing time, then the controller has sufficient time to process control channel packets, but the propagation time and network latency increase

Engineering Contradiction:
Improvecontroller processing capabilityVSAvoidnetwork latency
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The control packet headers are transmitted in advance in earlier timeslots (t_i) before the corresponding data packets arrive (t_i+k). This preliminary transmission allows the controller to process control information ahead of time, eliminating the need for delay elements and reducing network latency while ensuring the controller is ready when data packets arrive.

Inventive Principle:
Principle #10Preliminary action

2Manufacturing precision

If fiber delay line length is adjusted for precise alignment, then data channels and control channel are aligned at output, but the alignment process complexity increases

Engineering Contradiction:
Improvechannel alignment precisionVSAvoidalignment process complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

Control packet headers are sent in advance with a predetermined time offset k timeslots before the data packets they describe. This temporal advance notification eliminates the need for precise fiber delay line adjustments, as the controller receives control information ahead of time regardless of minor synchronization variations, thereby reducing alignment complexity.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP3386129B1Optical node and network with reduced latency
Publication Date: 2019.06.19 NOKIA SOLUTIONS & NETWORKS OY
  • EP3386129B1 patent drawingFigure 1~2
  • EP3386129B1 patent drawingFigure 3~4
  • EP3386129B1 patent drawingFigure 5

AI summary

Optical node (100) comprising: an input port (FI) suitable for receiving a WDM input signal comprising a plurality of data channels (λ1-λn) carrying data packets, and a control channel (λc) carrying control packets, wherein the data channels (λ1-λn) as well as the control channel (λc) are structured into equidistant timeslots, synchronized over all channels, each data channel carrying one packet per timeslot, the control packet carried on the control channel on time slot ti encapsulating a packet header for each data packet carried on a data channel on time slot ti+k, wherein k ≥ 1, a controller (10) being configured for disassembling the control packet carried on the control channel on time slot ti, and for disassembling the data packets carried on the data channel on time slot ti+k in function of the packet headers encapsulated in the control packet carried on the control channel on time slot ti.