拡張性のある波長ルーティング光ネットワークにおけるルーティング及び波長割当て方式

The exponential growth of the bandwidth demand for data transmission capacity has made an optical network a promising candidate for the future core network architecture. A wavelength-routed optical network (WRON) has the potential to meet rising demands for high bandwidth and low latency communication. In conventional WRON, it is more difficult to manage optical carriers as the number of wavelengths increases. In addition, it is difficult to manage the entire network with full knowledge of network resources on single-domain scenarios. In order to make the conventional WRON more scalable and manageable, researches on optical carrier management for metro/regional networks and domain-level partitioning for large-scale optical networks are conducted. Accordingly, wavelength reusable multi-carrier-distributed (WRMD) network is able to simplify the optical carrier management by placing a multi-carrier light source (MCLS) in an MCLS node, as the communication light source device. In order to utilize network resources efficiently, a large network that is partitioned into several domains, called multi-domain network, can take place. In this thesis, RWA schemes in WRMD network and multi-domain network are introduced. In the WRMD network, a routing and wavelength assignment (RWA) scheme is considered. The RWA scheme in the WRMD network must take into account both optical carrier connections and requested lightpaths using the reuse of the optical carrier connections while minimizing the number of required wavelengths. There are two investigated cases, depending on the number of MCLS nodes: either one or multiple. First, the RWA problem is formulated as the integer linear programming (ILP) problem of obtaining the minimum number of required wavelengths to satisfy the given lightpath setup requests. For large-scale networks, the ILP approach is not practical solution times. A heuristic RWA scheme is then introduced to solve the RWA problem in practical times. In the multi-domain optical network, a survivable RWA scheme, which provides complete end-to-end primary and backup path pairs, is considered. In this thesis, the survivable lightpath provisioning scheme that allows traffic splitting to minimize the cumulative cost of a set of paths is introduced. This scheme employs an ILP formulation based on hierarchical path computation with full-mesh topology abstraction. There are two phases in the scheme. The first phase solves the ILP problem on an inter-domain topology and then feeds the results as intra-domain requests. The second phase solves the ILP problem in each related domain. Finally, all the intra-domain solutions are concatenated along routing sequences. Moreover, three different protection strategies, namely same domain sequence, link disjoint, and domain disjoint, are considered with varying degrees of primary and backup route separation. The performance of the RWA schemes in each network is evaluated in many points as well as many different network topologies. Therefore, the schemes can provide reference values to gauge the existing distributed heuristics and to further analysis.電気通信大学201

Dynamic load balancing with learning model for Sudoku solving system

This paper proposes a dynamic load balancing with learning model for a Sudoku problem solving system that has multiple workers and multiple solvers. The objective is to minimise the total processing time of problem solving. Our load balancing with learning model distributes each Sudoku problem to an appropriate pair of worker and solver when it is received by the system. The information of the estimated solution time for a specific number of given input values, the estimated finishing time of each worker, and the idle status of each worker are used to determine the worker-solver pairs. In addition, the proposed system can estimate the waiting period for each problem. Test results show that the system has shorter processing time than conventional alternatives

IoTセンサーによる昭和基地遠隔監視

第14回南極設営シンポジウム 6月27日（火）国立極地研究所 極地観測棟3

Elastic optical network with spectrum slicing for fragmented bandwidth allocation

Elastic Optical Networks (EONs) allow the channel spacing and the spectral width of an optical signal to be dynamically adjusted and hence have become an important paradigm in managing the heterogeneous bandwidth demands of optical backbone networks. The entire available optical spectrum is divided into some spectrum slots which define the smallest granularity of bandwidth and optical signals with variable bandwidths can occupy different number of such slots. The constraints imposed by the physical layer of an EON require that the slots occupied by an optical signal from source to destination have to be consecutive and contiguous in terms of their relative position in the optical spectrum. Furthermore, the same spectrum slots need to be reserved throughout the entire optical signal\u27s path from its source to destination. The above constraints make the routing and spectrum allocation (RSA) in EONs very challenging because unavailability of enough spectrum slots that together equals the spectral width of the optical signal associated with an end-to-end request, will result in blocking of the request. Recent developments in the physical layer technologies have made all-optical ‘slicing’ of a request possible and make the request to be ‘fit’ into multiple non-consecutive spectral slots in an EON. But these all-optical ‘slicers’ employ complex technologies and can be very costly to employ. In this paper, we propose a spectrum allocation scheme for an EON node architecture with these ‘slicers’ and we also formulate a modified RSA scheme for EONs employing slicers, both as a mixed-integer linear programming (MILP) model and a heuristic algorithm. Our main aim is to analyze the tradeoff between the number of slicers that can be used per node versus the spectrum utilization and bandwidth blocking rate. The numerical results show that the proposed scheme with slicers can significantly improve bandwidth blocking rate, compared to the conventional scheme without slicer