Research On D~* Principle-based Dynamic Equilibrated Restoration Strategy In ASON

With the rapid development of Internet, the global data traffic growth is exponential. The dynamic, burst characteristics of data traffic present the high requirement to traditional optical transmission network (OTN). As a new technology of intelligent optical network, the appearance of automatically switched optical network (ASON) endue traditional optical transport network with unprecedented flexibility and expansibility. ASON represented the future direction of next generation networks (NGN). Hereinto, supporting many kinds of restoration strategy is an important characteristic of ASON. Multi-traffics carried in ASON demand the fast and multi-schemes restoration ability of network, simultaneity, reasonably and efficiently assign the network resources. However, at present, a series of restoration strategy there are designed for traditional optical transmission network are hardly satisfied with the survivability request of ASON. Therefore, the research on ASON restoration problem became a focus in ASON studies.D~* (D-star) algorithm is a heuristic search algorithm in dynamic environments. It is applied to paths planning in unknown, partially known, and changing state spaces, with advantages such as intelligence, high efficiency, robustness, and easy to actualize distributing, etc. Game theory is the method and architecture to research the phenomena with struggling or competitive characters. Based on researching the relative problem of ASON and restoration in ASON, the article design a dynamic equilibrated restoration strategy in ASON using D* algorithm and uniting game theory of mixed strategy to provide the restoration channel for failed traffic by routing and wavelength assignment. The purpose is to restore fault rapidly, simultaneously, to assign the network resources reasonably, and then to improve the rate of restoration and enhance survivability of network.In this thesis, the research is focus on restoration in ASON. The main works and innovative results are listed as follow:(1) Analyzing and summing up the background knowledge and influence factors related problems of restoration of ASON, which include framework and functions of control plane, architecture and modes of route, message distribution, the strategies of survivability and restoration, the techniques of dynamic route and wavelength assignment (RWA) etc. in ASON.(2) Researching the related theories of D~* algorithm and game theory of mixed strategy, and present a D~* principle-based dynamic equilibrated restoration strategy in ASON. Considering of the path cost and the occupancy of wavelength comprehensively, using game theory of mixed strategy to solve Nash equilibration between occupancy of wavelength and path cost, according this, the evaluation function of D~* algorithm is constructed dynamically, for ensuring a more equitable distribution of network resources in the process of dynamic channel restoration. Compared with traditional restoration strategy based on shortest path and simple dynamic restoration strategy, this algorithm can achieve higher restorability and lower resource occupancy.(3) According to the idea of the restoration strategy, the article detailedly analyze, design and carry out the principle of equilibrated D~* algorithm, which include constructing data structure and model of mathematic, flow design and capability analysis, etc. Against the disadvantage of slow convergence founded in simulation experiment, due to sloving nonlinear equations of Nash equilibrium, the article design a method which combining Newton iterative method with least square method to solve nonlinear equations of Nash equilibrium. It can be proved to accelerate convergent speed of the algorithm by simulation.(4) Using C# and MATLAB integrated programming, the article design simulation system of restoration strategy independently, and test the performance of equilibrated D~* algorithm by simulating actual network environment. In addition, we compare equilibrated D~* algorithm with shortest path algorithm and simple D~* algorithm which designed separately. It shows that the blocked rate, restorable rate and rate of resource occupancy of equilibrated D~* algorithm, are all obviously better than other comparative algorithms, and the performance of time of equilibrated D~* algorithm can sufficiently fit the request of restoration time in ASON.