Research On Multi-Criteria Satisfactory Optimization Method And Application

With the rapid development and popularity of IP networks, the construction of IP networks can be seen in everywhere of the world. Therefore, the study of networks optimization is becoming more and more important. The way to optimize networks with the constraint of user's requisition and construct economical, high performance and stable networks becomes an essential part of network optimization research. The traditional optimization design focuses on getting the "best" solution, but because most networks optimization problem involve multi-constraint and multi-criteria optimization problem, the traditional optimization becomes an NP-complete problem. To obtain the "best" solution needs not only complex algorithm, but also a long computational time. The computational time can become so long that the algorithm cannot be used to solve the practice problems. In this dissertation, a concept of satisfactory solution is proposed to take place traditional optimum solution, a application method of satisfactory optimization is proposed to study networks optimization problems which topology is given.This thesis focus on the study of satisfactory multi-criteria optimization method and related technologies. And a new method on optimization of computer network based on satisfactory multi-criteria optimization is proposed .The thesis mainly discusses the following problems:1) The limitation of the traditional optimum theory is analyzed. The present situation of satisfactory theory and satisfactory optimization are summarized. Satisfactory multi-criteria optimization has been studied deeply and systematically. And a satisfactory multi-criteria optimization model is established. This thesis uses this model as the evaluation system of optimization scheme, and selects GA(Genetic Algorithm) as the search tool to search the potential optimization solution. The evaluation system and GA are unified into the same architecture to become a complete solving model of satisfactory multi-criteria optimization.2) The proposed multi-criteria optimization model is used to solve the capacity and flow assignment problem of computer communication networks. Fist, a mathematic model of capacity and flow assignment of computer communication networks is described. Second, a suitable GA algorithm is designed to solve this optimization problem. And routing strategies between nodes and links capacity are get by optimizing. Simulations are made on some examples. Results of simulation demonstrate that the proposed Multi-Criteria Satisfactory optimization method has a fast convergence speed and good stabilization.3) The proposed multi-criteria optimization model is also used to solve the problem of OSPF link weight optimization. On the basis of comprehensive consideration of link utilization, packet loss rate, delay and link cost, Multi-Criteria Satisfactory optimization mathematic model for OSPF link weight optimization is constructed. And a suitable GA is designed to solve this problem. Then a traditional IP routing method (OSPF) is used to allocate the flow over links. Results of simulations demonstrate that Multi-Criteria Satisfactory method can balance network load distribution and improve the total network throughput.