Passive Optical Network Flexible Roundtrip Delay
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Solution Overview
Problem
Passive optical networks (PONs) face inefficiencies due to uniform transmission delay times across all optical network units (ONUs), which can lead to undue burdens on network usability, especially for applications requiring quick data response, as the delay time is determined by the maximum distance to the most remote ONU, affecting users closer to the optical line termination (OLT) with longer delays.
Innovation Solution
The optical line termination device creates individual bandwidth maps for each ONU, including a frame identifier based on the transmission delay time between the ONU and the OLT, allowing upstream data transmission in specific frames tailored to each ONU's delay, and incorporates a cascading ONU for signal amplification and extended network reach, enabling flexible frame allocation and reduced delay times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a common delay time determined by the maximum distance is used for all ONUs, then the network can accommodate the most remote ONU, but ONUs located at a small distance from the OLT suffer from relatively large delay time
Solution Approach 1:
The patent segments the upstream transmission opportunities into different frames for different ONUs. Specifically, it assigns different frame identifiers to different ONUs in the bandwidth map, allowing each ONU to transmit in a frame appropriate to its distance from the OLT. This segmentation resolves the contradiction by enabling remote ONUs to use later frames (accommodating their distance) while near ONUs use earlier frames (minimizing their delay).
Solution Approach 2:
The patent applies local quality by customizing the transmission parameters for each ONU based on its specific characteristics, particularly its distance from the OLT. The bandwidth map is generated with ONU-specific frame identifiers that reflect individual transmission delay times. This allows each ONU to have optimized transmission characteristics suited to its local condition, resolving the contradiction between uniform network coverage and location-specific delay optimization.
2Stability of the object's composition
If the delay time is determined by the maximum distance to the most remote ONU, then all ONUs can synchronize their transmissions, but applications requiring quick data response suffer from undue burden on network usability
Solution Approach 1:
The patent introduces dynamics by making the frame allocation flexible rather than static. The bandwidth map dynamically assigns different frame identifiers to different ONUs based on their individual transmission delay times. This dynamic allocation allows the system to adapt to varying distance conditions while maintaining synchronization, resolving the contradiction between stable synchronization and flexible usability for time-sensitive applications.
Solution Approach 2:
The patent applies preliminary action by pre-calculating and embedding the appropriate frame identifier in the bandwidth map for each ONU before transmission occurs. The OLT determines the optimal frame for each ONU based on its distance and pre-assigns it in the bandwidth map message. This preliminary configuration enables each ONU to transmit at the optimal time without real-time negotiation, maintaining synchronization while optimizing response times for different applications.
3Device complexity
If upstream data transmissions occur in the same network data frame, then bandwidth allocation can be simplified, but ONUs at different distances experience unequal delay times affecting performance
Solution Approach 1:
The patent changes the frame identifier parameter in the bandwidth map to reflect individual ONU characteristics. Instead of using a uniform frame assignment, the system modifies the frame parameter based on each ONU's distance from the OLT. This parameter change enables the system to maintain relatively simple bandwidth allocation procedures while achieving optimized delay times for each ONU, resolving the contradiction between allocation simplicity and delay optimization.
Data Source
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Figure 3
AI summary
Passive optical network, comprising an optical line termination device and a first and a second optical network unit, the optical line termination device comprising a processor, the processor being configured to send and receive network signals comprised in frames, and the processor being further configured to create a bandwidth map for each of said optical network units, each bandwidth map specifying an allocated upstream data transmission time period, wherein the processor is further configured to include a frame identifier in each of said bandwidth maps, the frame identifier individually specifying a frame for upstream data transmission for the optical network unit, wherein the frame specified for the first optical network unit is different from the frame specified for the second optical network unit.