OLT Packet Arrival Tracking for Low-Latency PON Timing
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Solution Overview
Problem
Existing PON systems, particularly those employing the DBA scheme, suffer from latency issues due to the time required for communication of transmission requests and responses between the ONU and OLT, making them unsuitable for low-latency applications like remote medical care and autonomous driving without requiring special interfaces or protocols.
Innovation Solution
An OLT system that includes processing circuitry to collect packet arrival and data information, determine transmission timing based on allocated timing and data amount, and adjust allocation timing to ensure that packets from ONUs with low-latency requests are transmitted as intermediate packets without buffering, while maintaining standard DBA for other ONUs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If dynamic bandwidth allocation (DBA) scheme is employed to avoid unused bands, then bandwidth utilization is improved, but transmission latency increases due to communication overhead between ONU and OLT
Solution Approach 1:
The patent segments the bandwidth allocation into two distinct schemes: FBA (Fixed Bandwidth Allocation) for low-latency services and DBA (Dynamic Bandwidth Allocation) for other services. This segmentation allows critical low-latency traffic to bypass the latency-inducing DBA process while non-critical traffic continues to benefit from efficient DBA-based allocation, thus resolving the contradiction between bandwidth utilization and transmission latency.
Solution Approach 2:
The patent applies different quality characteristics of bandwidth allocation to different service types. Low-latency services receive guaranteed fixed bandwidth with deterministic transmission timing, while other services receive dynamically adjusted bandwidth. This local differentiation in allocation quality enables simultaneous optimization for both latency-sensitive and efficiency-sensitive traffic flows.
2Loss of time
If fixed bandwidth allocation (FBA) scheme is employed to guarantee transmission timing, then transmission latency is reduced, but bandwidth utilization deteriorates due to unused bands
Solution Approach 1:
The patent divides the service portfolio into two categories: low-latency services that require fixed timing guarantees and other services that prioritize bandwidth efficiency. By allocating specific bandwidth portions to each category with appropriate schemes, the system achieves both low latency for critical services and high utilization for non-critical services, eliminating the trade-off present in pure FBA or DBA systems.
Solution Approach 2:
The patent introduces dynamic service classification and adaptive bandwidth allocation. The system dynamically determines which services require low-latency treatment and adjusts bandwidth allocation in real-time based on service requirements and network conditions. This dynamic approach allows the system to switch between FBA and DBA characteristics as needed, optimizing both latency and utilization.
3Productivity
If DBA scheme communicates transmission requests and responses between ONU and OLT, then bandwidth allocation efficiency is improved, but system complexity increases
Solution Approach 1:
The patent extracts the complex DBA communication and control mechanisms from the low-latency service path. By isolating these complexity-inducing elements to only affect non-critical services, the system maintains simple, predictable transmission for low-latency services while still benefiting from sophisticated bandwidth management for other traffic. This extraction reduces the effective complexity experienced by time-sensitive operations.
4Reliability
If FBA scheme allocates fixed bands to each ONU, then transmission timing is guaranteed, but unused bandwidth is generated
Solution Approach 1:
The patent segments bandwidth allocation by service type rather than uniformly applying FBA to all services. Critical low-latency services receive fixed allocations with timing guarantees, while non-critical services share remaining bandwidth through dynamic allocation. This segmentation ensures timing reliability where needed while eliminating wasteful unused bandwidth in other contexts.
Solution Approach 2:
The patent changes the allocation parameter from static fixed bandwidth to a hybrid model where bandwidth and allocation method vary by service type. Low-latency services maintain fixed parameters for reliability, while other services use variable parameters optimized for utilization. This parameter differentiation resolves the contradiction between guaranteed timing and eliminating unused bandwidth.
Data Source
AI summary
An OLT used for a PON using an optical splitter includes processing circuitry. The processing circuitry is configured to collect time information regarding arrival of packets from an ONU and amount-of-data information of the packets. The processing circuitry is configured to determine transmission timing of the ONU based on transmission timing information allocated to the ONU, the time information, and the amount-of-data information.