Research On Access Selection Algorithms For Heterogeneous Wireless Networks

With the development of mobile communication technology and computer integrated circuits,as well as the improvement of social and economic development level,mobile wireless communication technology presents a rapid development trend,the user's demand for data transmission rates is increasing,at the same time,the demand for quality of service for diversified services is also increasing.Due to the differences in various wireless access technologies and the inability of a single network technology to meet the diversified quality of service requirements of users anytime and anywhere,therefore heterogeneous wireless networks integration become inevitable,and makes the current networks have formed an organic whole.Therefore,the next-generation mobile communication network will be a integrated heterogeneous network,and how to select the best network from it,that is,to designing a feasible network selection algorithm,is one of the key technologies for heterogeneous network integration.At present,in the research of heterogeneous wireless network access selection algorithm,there has been a lot of research,but researchers have different starting points and focuses.So far,no feasible network access selection scheme has been formed.On the contrary,a good network selection algorithm can not only maximize the utilization of network resources,but also provide mobile terminals with diversified Qo S requirements of high speed,high security,low energy consumption and low delay.Therefore,it is extremely necessary to construct an efficient network selection algorithm.In response to the above problems,the research content of this thesis is as follows:(1)In the current heterogeneous network,the multi-decision attribute vertical handover algorithm is difficult to dynamically adjust the weight value of the network attributes,and thus cannot meet the user's quality of service requirements.To solve this issue,this thesis aims at accessing the optimal heterogeneous wireless network and guaranteeing the user's Qo S,and proposes an adaptive vertical handover algorithm based on the fuzzy hierarchy-entropy weight method.First,according to user experience,a model of network attribute optimization is constructed by combining subjective fuzzy hierarchical weighting and objective entropy weights;then,an adaptive mechanism is used to dynamically adjust the weight value of each network attribute according to user experience;finally,the cost function is used to predict the state of the heterogeneous network to select the optimal wireless network.Simulation experiments verify that the proposed algorithm can effectively reduce the network switching rate,better ensure load balancing between heterogeneous wireless networks,and increase the endurance of mobile terminals.(2)Aiming at the problem that the current network selection algorithm is not highly recognizable to the optimal network and the sub-optimal network,which causes users to switch networks frequently and reduces user's Qo S.This thesis proposes a network selection algorithm based on weighted chi-square distance and genetic algorithm,and introduces the steps and process of the algorithm in detail.First,determine the initial weight of each attribute according to the user's service demands,use the weight as the initial iterative solution,and then use the weighted chi-square distance to construct the fitness function of the genetic algorithm.Then,the weight is dynamically adjusted by selection operator,crossover operator and mutation operator.Finally,the network with the highest fitness is selected as the best network.Algorithm comparison simulation experiments show that the algorithm proposed in the thesis significantly expands the score difference between the best network and the sub-optimal network,and has higher recognizability,which makes it easier for decision makers to decide the choice result,and to a certain extent alleviates the ping-pong effect.