Flexible Grid Spectrum Slot Allocation for Optical Networks
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Solution Overview
Problem
Conventional Routing and Wavelength Assignment (RWA) solutions are not applicable to bandwidth-variable optical cross-connects (BV-OXCs) due to different bandwidth granularity and optical signals, making it challenging to efficiently manage flexible grid technology in wavelength switched optical networks.
Innovation Solution
A method and apparatus for routing and bandwidth assignment in wavelength switched optical networks that selects routes and assigns adjacent frequency slots, placing wider paths at one end of the spectrum and narrower paths at the opposite end, optimizing slot usage and reducing blocking probability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional RWA solutions are used, then routing and wavelength assignment is simple, but they are not applicable to BV-OXCs with different bandwidth granularity
Solution Approach 1:
The patent changes the fundamental parameter of bandwidth granularity from fixed to variable. By introducing flexible grid spacing that can be configured per port, the system adapts to different bandwidth requirements of optical signals, making conventional RWA applicable to BV-OXC environments while maintaining computational manageability through structured parameterization.
Solution Approach 2:
The patent introduces dynamic configuration capability where the grid spacing and bandwidth allocation can be adjusted in real-time based on traffic demands. This dynamic adaptation allows the network to optimize resource utilization for different modulation formats and bit rates, resolving the contradiction between adaptability and complexity through controlled dynamic behavior.
2Productivity
If flexible grid with configurable bandwidth is implemented, then bandwidth efficiency is improved, but path computation becomes more difficult
Solution Approach 1:
The patent segments the flexible spectrum into discrete configurable bandwidth units that can be independently allocated. By dividing the continuous spectrum into manageable segments with defined granularity, the complex path computation problem is broken down into smaller, more manageable allocation decisions, maintaining productivity while reducing computational difficulty.
Solution Approach 2:
The patent implements preliminary configuration of grid spacing and bandwidth parameters before actual path computation. By pre-establishing the flexible grid structure and available bandwidth segments, the system prepares the computational environment in advance, making subsequent path computation more efficient and less complex while maintaining high bandwidth efficiency.
3Ease of operation
If first fit technique is used for frequency slot assignment, then assignment is simple, but blocking probability increases for wider paths
Solution Approach 1:
The patent inverts the conventional first-fit assignment strategy by implementing a reverse approach where wider paths are assigned first or where available bandwidth segments are allocated in a manner that preserves larger contiguous segments. This inversion reduces blocking probability for wider paths while maintaining operational simplicity by reversing the logical sequence of allocation decisions.
Solution Approach 2:
The patent changes the assignment parameter from simple sequential allocation to bandwidth-aware allocation that considers the dimensions of requested paths. By modifying the assignment logic to account for path bandwidth requirements and available spectrum segments, the system reduces blocking probability while keeping the assignment process operationally simple through parameterized decision rules.
Data Source
AI summary
Routing and bandwidth assignment of new paths of different bandwidths, occupying different numbers of adjacent frequency slots in a wavelength switched optical network, involves selecting a route, and assigning a set of adjacent frequency slots. The assignment can place wider bandwidth ones of the new paths at an opposite end of a spectrum of the available frequency slots, to an end where narrower bandwidth ones are placed. A size of sets of available adjacent slots remaining after the assignment is likely to be increased, compared to a conventional first fit assignment. A wider subsequent new path can sometimes be accommodated along all or some of the route and thus the blocking probability can be lowered. The selecting of which of the possible routes to use can be made dependent on which has more sets of available adjacent frequency slots, or which has a wider gap between occupied slots.