Research On Network Selection Algorithm In Heterogeneous Wireless Networks

With the continuous development of mobile communication technology, the future of mobile communications networks cannot be a single of a network, but a variety of wireless access technologies coexist, complement and mutual integration each other, forming a heterogeneous wireless networks. The multi-mode mobile terminal can be connected to different networks. Therefore, heterogeneous network access selection issue has become a hot research topic. Generally Heterogeneous network selection algorithm comprises two key issues, to calculate network parameters weights and candidate networks merit-based sorting. Based on the study of the existing algorithms, respectively, the two issues have been studied, and proposed a network selection algorithm based on fuzzy comprehensive weight (FCW) and vector projection sorting.To calculate the network weight, most of the traditional network selection algorithms are based on subjective judgments of experts or decision makers, without considering the impact of the objective existence of actual network parameters, with one-sidedness. In this paper, it combined both subjective and objective factors and put forward an integrated weight calculation method based on the FCW. Firstly, on the basis of AHP algorithm, introduces the theory of triangular fuzzy numbers to calculate the subjective weight, reduce the complexity of the algorithm; and for the objective weights, defines the concept of the coefficient of variation, using information entropy and standard dispersion theory, calculating the objective weights reflect the degree of variation in the actual network parameters. Finally, combine the subjective and objective weight to fuzzy comprehensive weights.For the sorting of candidate network, this paper introduces the principle of mathematics vector projection, proposed sorting algorithm based on vector network projection. The algorithm defines the concept of the ideal virtual network by calculating the value of the candidate on the virtual network projector ideal network to measure how close it is to the ideal values, and then complete the merit-based sorting network.Finally, combine the FCW and vector projection ordering, using FCW to calculate the weight of network parameters, and then using the vector projection ordering complete the process of network decisions selection. Simulation results show that the algorithm reduces the user blocking rate, reducing unnecessary switching algorithm, the performance is better than AHP and WLAN priority algorithm.