Optical Filter Fiber Padding for Upstream-Downstream Latency Balance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Latency imbalance at optical filters in 5G networks is not adequately controlled, leading to potential performance issues due to differences in delay symmetry between upstream and downstream channels, which can exceed the allowed margin of 65 ns.
Innovation Solution
Introduce latency padding within optical filter modules by adding a specific length of fiber to offset the latency imbalance between coupled channels, using methods such as determining fiber length based on nominal splice length, measured path lengths, or actual delays to equalize latencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If thin film filter modules use cascaded 3-ports single filters spliced together, then cost-performance and flexibility are improved, but latency imbalance between upstream and downstream channels increases
Solution Approach 1:
The patent applies local quality by introducing different fiber lengths (padding) into specific channels based on their individual latency requirements. Each channel receives a customized fiber padding length calculated to compensate for its specific path length difference, creating local adjustments rather than uniform treatment across all channels. This resolves the latency imbalance while maintaining the cost-effective cascaded filter structure.
Solution Approach 2:
The patent changes the fiber length parameter in each channel to adjust and equalize latencies. By calculating the required padding length based on path length differences and adding appropriate fiber extensions to specific channels, the system modifies the physical parameter (fiber length) to achieve latency equalization without changing the filter architecture itself.
2Manufacturing precision
If fiber padding is added to offset latency imbalance, then latency equalization is improved, but device complexity increases
Solution Approach 1:
The patent applies preliminary action by calculating and determining the required fiber padding lengths during the manufacturing planning stage, before actual assembly. The method computes the exact padding length needed for each channel based on measured or nominal path lengths, allowing all padding components to be prepared in advance. This streamlines the manufacturing process and reduces on-site complexity despite the additional components required.
Data Source
AI summary
A padding unit comprising one or more fiber paddings is provided. Each of the one or more fiber paddings is for a respective one of one or more pairs of coupled channels in an optical device. At each pair of coupled channels, one channel in the pair of coupled channels is used as an upstream channel and the other channel in the pair of coupled channels is used as a downstream channel. Each fiber padding comprises a padding length of fiber configured to offset at least a part of a latency imbalance at the respective pair of coupled channels, the latency imbalance being a difference in latencies between the respective upstream and downstream channels caused by a difference in the multiplexing or demultiplexing path lengths of the respective upstream and downstream channels.