Optical Line Terminal ONU Registration Coordination
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Solution Overview
Problem
In passive optical networks (PON), a significant delay occurs during upstream service data transmission due to the silent window required for ONU registration, which fails to meet the delay requirements of delay-sensitive services, particularly in mobile bearer systems where the interface between the BBU and RRU necessitates a delay of less than 100 µs, while the silent window typically lasts for 200 µs to 250 µs.
Innovation Solution
The proposed solution involves methods where the OLT sends an ONU registration request message to the BBU, which temporarily stops allocating bandwidth resources to user equipment, allowing the OLT to initiate registration without interrupting upstream data transmission, by determining an appropriate silent window size and registration start time, ensuring no data is sent during registration, thus avoiding delays and conflicts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the OLT opens a silent window for ONU registration, then the ONU can be registered successfully, but the upstream service data transmission is delayed by 200 µs to 250 µs
Solution Approach 1:
The BBU sends a registration request message to the OLT in advance, indicating that an ONU registration is about to occur. The OLT then proactively stops allocating upstream bandwidth resources to ONUs before the silent window begins, ensuring that no upstream data transmission occurs during the registration period. This preliminary action prevents the need to wait for the silent window to end before resuming data transmission, thereby eliminating the 200-250 µs delay.
Solution Approach 2:
The BBU provides feedback to the OLT by sending a registration request message when it detects that an ONU registration is about to occur. The OLT responds by adjusting its bandwidth allocation strategy, stopping upstream resource allocation upon receiving the registration request. This feedback mechanism enables coordinated action between the BBU and OLT to prevent data transmission during registration without requiring the system to wait for the silent window to complete.
2Reliability
If the OLT stops allocating upstream bandwidth to ONUs during registration, then data conflicts are avoided, but the service transmission delay increases
Solution Approach 1:
Instead of stopping bandwidth allocation after the silent window begins (reactive approach), the OLT stops allocating upstream bandwidth resources upon receiving the registration request message from the BBU (proactive approach). This preliminary stopping of bandwidth allocation ensures that no upstream data is transmitted during the registration period, avoiding data conflicts while eliminating the delay that would occur if bandwidth allocation were resumed only after the silent window ended.
3Loss of time
If the silent window duration is reduced to meet delay requirements, then service delay is improved, but registration reliability deteriorates
Solution Approach 1:
The registration request message acts as an intermediary signal between the BBU and OLT, enabling them to coordinate their actions without requiring a fixed silent window duration. When the BBU sends this message, the OLT understands that registration is occurring and proactively stops bandwidth allocation. This intermediary mechanism allows the system to maintain reliable registration while meeting strict delay requirements, as the actual silent window duration becomes flexible rather than fixed at 200-250 µs.
Data Source
Figure 1~1a
Figure 2
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AI summary
This application discloses a data communications system, an OLT, and a BBU, and relates to the optical communications field. An OLT sends an optical network unit ONU registration request message to a baseband unit BBU, and starts the ONU registration after receiving a response message from the BBU, and the BBU temporarily stops allocating a bandwidth resource, to avoid impact of the ONU registration on a delay-sensitive service, so that during the ONU registration, the BBU temporarily stops allocating the resource to UE, thereby improving user satisfaction.