Research On QoS Routing Algorithm Based On Satisfactory Optimization

For new network service models, most of routings have multiple QoS constraints and traditional routing algorithm can't meet the user's QoS requirement. In recent years, multiple constrained QoS routing problem has caught researchers' eyes gradually. However, most researchers focus on "best" path with multi-QoS constraints. They usually treat some QoS parameters as constraints or punishment functions of routing, so that multi-QoS parameters can be converted into a single objective. Therefore they can pick up the "best" path according to the constraints. These researches neglect some problems as follows: firstly, it's difficult to convert multiple objectives into single objective because of unmeasured and contradictory characteristic that is consisted in different optimization parameters. Secondly, multiple constrained QoS routing problem is an NP-complete problem. Usually, it's hard to find the "best" path and even sometimes there isn't any "best" path. Thirdly, when dealing with QoS routing problems, researchers rarely refer to calculational methods of QoS parameters.This paper analyzes and discusses the theory and technology of multiple constrained QoS routing and then brings forward a new QoS routing solution based on satisfactory optimization which can solve the problems mentioned above. The main contributions of this thesis are as follows:1) Study QoS architectures and analyze the methods for guaranteeing QoS such as packet scheduling, traffic shaping and so on, then deduce calculational methods of QoS parameters based on M/M/1 queuing model, QoS control mechanisms, network calculation.2) Establish multi-objective satisfactory optimization model for QoS routing to solve the problems of traditional routing algorithm. The essence of this model is "satisfactory" path instead of "best" path. How to design satisfactory function and synthetical satisfactory rate function for QoS parameters is disscussed. Therefore each optimization objective without consistent measurement can be converted into a form of performance specification, which not only settles the problem of unmeasured characteristic existed in different QoS parameters, but also makes it possible to build up an easier and more reasonable routing criterion to optimize multiple QoS parameters simultaneously.3) Simulations are made on network Uni-cast and Multi-cast routing for the algorithm proposed above. Results of simulation demonstrate that it is effective and feasible for QoS routing.