Research On Spectrum Defragmentation Of Flexible Spectrum Optical Networks

With the exponentially increasing demand for communication bandwidth and variety of communication services, there is an urgent calling for efficient all-optical networks with ultra-large capacity for dynamically varying traffic. Based on OFDM, flexible bandwidth optical networks break through limitations of WDM optical networks due to ’one-size-fits-all’. While the fine-grained spectrum presents obstacles to RSA issue. The main achievements to deal with spectrum allocation and optimization in this paper are as follows.(1) We propose link and route respectively based spectrum resource description scheme, offering theoretical basis for the following Algorithms. The former introduces a spectrum coherence degree of ’adjacent-link pair’ to characterize common spectrum consecutiveness between certain link pair The latter introduces spectrum coherence degree of fiber path to characterize the capacity of spectrum exchange and the bandwidth mode carrying.(2) We propose an optimized algorithm for RSA based on ACO. Considering the spectrum continuity of global network, the new method screening the best fiber path by positive feed-back effect in ACO algorithm, which has the lowest impact and damage to the common available spectrum connectivity to the whole network. ACO-MCI method achieves a higher spectrum utilization and good performance for fragment mitigation.(3) We also propose MOSC method to effectively mitigate spectrum fragmentation in flexible bandwidth optical networks. Instead of spectrum reconstruction, in which case services working on certain fiber path may be disturbed and damaged, MOSC algorithm aggregates spectrum fragment through multi-fiber paths the so-called spectrum fragments can also be effectively used. The connection request with larger bandwidth demand can be easily allocated without damaging existing services along the fiber path, in which way a lower blocking rate can be achieved.