Optical WDM Network Fragmentation Measurement via Bit Maps
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Solution Overview
Problem
Existing methods for measuring network fragmentation in optical WDM networks do not account for fiber correlations, leading to suboptimal spectral efficiency and increased connection blocking due to inadequate assessment of spectral fragmentation.
Innovation Solution
A novel procedure that finds K-shortest routes between nodes, performs bit-wise logical AND operations on fiber bit vectors to create a bit map of routes, and calculates the probability of provisioning connections to determine the fragmentation factor, considering correlations in fiber states and available/occupied spectrum.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If flexible grid network architecture is used to optimize spectral efficiency, then spectral efficiency is improved, but network fragmentation increases
Solution Approach 1:
The patent performs preliminary actions by calculating K-shortest routes and pre-computing bit maps for all possible node pairs before connection requests arrive. This allows the network to proactively identify fragmentation issues and plan defragmentation actions before they block new connections, thus maintaining spectral efficiency while preventing fragmentation-related blocking.
Solution Approach 2:
The patent implements dynamic defragmentation by continuously monitoring network state through bit maps and fragmentation metrics, and adaptively selecting routes and time slots for defragmentation operations. The system dynamically adjusts defragmentation decisions based on current traffic patterns and fragmentation levels, allowing the network to transition between optimized and defragmented states as needed.
2Reliability
If network defragmentation is performed to reduce fragmentation, then connection blocking is reduced, but network complexity increases
Solution Approach 1:
The patent segments the complex defragmentation problem into manageable components: (1) calculating K-shortest routes between node pairs, (2) computing bit maps for each route, (3) evaluating fragmentation metrics, and (4) selecting defragmentation actions. This segmentation allows each sub-problem to be solved independently using standardized algorithms, reducing overall system complexity while achieving effective defragmentation.
Solution Approach 2:
The patent introduces bit maps as an intermediary data structure that compactly represents the state of spectrum slots across multiple fibers and routes. Instead of directly managing complex multi-dimensional network state, the system uses bit maps as an intermediate representation that simplifies fragmentation analysis and defragmentation decision-making, thereby reducing computational complexity.
3Ease of operation
If existing fragmentation measurement methods are used, then measurement simplicity is maintained, but measurement precision is insufficient
Solution Approach 1:
The patent extends fragmentation measurement from a single-dimension approach (overall network fragmentation) to a multi-dimensional approach by calculating fragmentation metrics for each fiber, each route, and each node pair separately using bit maps. This dimensional expansion provides precise localization of fragmentation issues while maintaining computational efficiency through the compact bit map representation, thus achieving both precision and simplicity.
Data Source
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AI summary
A method implemented in a network apparatus used in a wavelength division multiplexing (WDM) optical network is disclosed. The method includes (a) finding K-shortest routes between each node pair (s, d), where s, d ∈ V and |V| ≤ K, where V is a set of reconfigurable optical add-drop multiplexer (ROADM) nodes, (b) selecting unconsidered node pair (s, d), (c) selecting unconsidered route k between nodes s and d out of the K-shortest routes, (d) finding a bit map of route k by performing bit-wise logical AND operation on bit vectors of fibers along route k, (e) selecting unconsidered line rate l out of offered set L of line rates, and (f) finding a probability αl s,d,k of provisioning a connection with line rate l. Other apparatuses, systems, and methods also are disclosed.