Optical Spectrum Entropy Routing for Fragmentation Reduction
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Solution Overview
Problem
The existing fixed wavelength grid approach in optical networks is inadequate for bit rates greater than 100 Gb/s, leading to inefficient spectrum usage and fragmentation, as it cannot accommodate varying bit rates and distances, resulting in wasted spectrum capacity and the need for costly new links to manage increasing traffic levels.
Innovation Solution
A routing and wavelength assignment method that calculates spectrum entropy using a logarithmic Shannon information entropy approach to select blocks of spectrum resources with lower entropy values, allowing for flexible allocation and minimizing fragmentation, thereby optimizing spectrum resource utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If fixed wavelength grid approach is used, then network simplicity and ease of operation are maintained, but spectrum efficiency deteriorates and spectrum fragmentation increases for bit rates greater than 100 Gb/s
Solution Approach 1:
The patent applies dynamics by transitioning from a static fixed grid to a dynamic elastic grid where wavelength slots can be flexibly allocated and reassigned based on current network demands. The routing and wavelength assignment method dynamically calculates entropy values and reallocates spectrum resources to match varying bit rate requirements, enabling the network to adapt its spectrum usage pattern continuously rather than being constrained by predetermined fixed slots.
Solution Approach 2:
The patent changes the parameter of wavelength slot allocation from fixed to variable. By introducing entropy-based optimization, the system continuously adjusts spectrum allocation parameters (wavelength assignments, slot widths, and positions) to minimize fragmentation while accommodating different bit rates. This parameter transformation allows the network to optimize spectrum efficiency without sacrificing operational simplicity.
2Device complexity
If fixed wavelength slots are allocated, then network configuration is simplified, but spectrum resource utilization deteriorates due to inability to accommodate varying bit rates and distances
Solution Approach 1:
The patent implements self-service through automated entropy-based wavelength assignment. The system autonomously calculates entropy values for different wavelength slot configurations and automatically selects optimal allocations without requiring manual network configuration. This self-service mechanism enables flexible spectrum resource utilization while keeping network configuration complexity low, as the optimization process occurs automatically based on current network state.
Solution Approach 2:
The patent incorporates feedback through continuous entropy calculation and optimization. The system monitors spectrum usage patterns, calculates entropy values for different allocation scenarios, and uses this feedback to adjust wavelength assignments in real-time. This closed-loop feedback mechanism ensures high spectrum resource utilization while maintaining simple network configuration, as the system learns and adapts based on observed network conditions.
3Ease of operation
If spectrum slots are allocated based on fixed grid, then wavelength assignment is straightforward, but spectrum fragmentation increases leading to wasted spectrum capacity
Solution Approach 1:
The patent applies preliminary action by pre-calculating entropy values for potential wavelength assignments before actual spectrum allocation. The system evaluates multiple possible configurations in advance, identifies optimal assignments that minimize fragmentation, and then executes these pre-determined allocations. This preliminary optimization reduces spectrum capacity waste while maintaining wavelength assignment simplicity, as the complex optimization work is performed beforehand rather than during real-time operation.
Data Source
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AI summary
A routing and wavelength assignment method for use in an optical fibre system, comprising (i) identifying a plurality of paths between a source node and a destination node, (ii) selecting one of the plurality of identified paths, (iii) defining within the spectrum band of the selected path one or more blocks of spectral resource, in which each block comprises either: one or more unused wavelength channels, or one or more wavelength channels having the same spectral width, (iv) obtaining an entropy value of the selected path defining the spectrum fragmentation across its spectrum band, based on a logarithm of the ratio of the number of wavelength channels in each of the one or more blocks, to the total number of wavelength channels across the spectrum band, (v) iterating steps (ii) to (v) until the entropy value of each of the plurality of identified paths has been determined, and (vi) choosing from the plurality of identified paths a path having the lowest entropy value.