Greedy Channel Selection for Flexible Optical WDM Spectrum Allocation
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Solution Overview
Problem
Current fixed grid optical WDM networks are inefficient in spectrum allocation due to fixed channel spacing, leading to suboptimal spectral efficiency across varying line rates, and existing solutions for flexible networks face scalability issues with Integer Linear Programming, particularly in routing, wavelength assignment, and spectrum allocation.
Innovation Solution
A greedy channel selection procedure that identifies the lowest available wavelength for connections, selects channels on the first available K wavelengths, and routes them through the minimum number of optical fiber paths to minimize total spectrum requirements, addressing spectral continuity and conflict constraints.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If Integer Linear Programming is used to solve the RWSA problem in flexible optical WDM networks, then solution optimality is improved, but computation time increases exponentially with system size
Solution Approach 1:
The patent segments the RWSA problem into three independent sub-problems: routing determination, wavelength assignment, and spectrum allocation. This segmentation allows each sub-problem to be solved separately using greedy algorithms, avoiding the exponential complexity of solving the complete problem with Integer Linear Programming while still achieving near-optimal solutions.
Solution Approach 2:
The patent employs greedy algorithms as a computationally inexpensive alternative to Integer Linear Programming. While greedy algorithms may not always produce the absolute optimal solution, they provide sufficiently good solutions with dramatically reduced computation time, making them practical for large-scale flexible optical WDM networks.
2Device complexity
If fixed channel spacing is used in optical WDM networks, then channel assignment is simplified, but spectral efficiency decreases for mixed line rate systems
Solution Approach 1:
The patent introduces dynamic channel spacing in flexible optical WDM networks, where the spectral width of each channel is adjusted according to its line rate requirements. High line rate channels are allocated larger spectral widths while low line rate channels use smaller spectral widths, optimizing spectral efficiency while maintaining manageable assignment complexity through systematic allocation rules.
3Measurement precision
If spectral continuity constraint is enforced in flexible optical WDM networks, then wavelength assignment accuracy is improved, but device complexity increases
Solution Approach 1:
The patent separates the RWSA problem into distinct stages, with wavelength assignment handled independently from spectrum allocation. The spectral continuity constraint is enforced during the wavelength assignment stage, ensuring that the same wavelength is assigned to all links of a connection, while spectrum allocation is handled separately to assign appropriate spectral widths based on line rate requirements.
Data Source
AI summary
The inventive method, implemented in an optical flexible wavelength division multiplexing FWDM network, includes finding a connection route in an optical FWDM network on which a channel with sufficient spectrum is available at lowest wavelength among all available channels, finding K channels at first available K lower wavelengths out of available channels for minimizing total required spectrum; and selecting a channel which is routed through minimum number of optical fiber paths out of the K available channels at one of the lower wavelengths.