Research On Modeling And Coopereaion Of Smart Collaborative Network Components In High-Speed Railway Scenarios

As the mobile Internet is playing a pivotal role in various areas of social and economic activities,the service of mobile Internet access has become an integral part of our daily lives.However,the experience of Internet service in the High Speed Railway(HSR)scenario is not as good as that in stationary scenarios.The aim of this dissertation is to overcome the above challenge with the adoption of Smart Collaborative Network(SCN)architecture and SCN schemes.This dissertation focuses on three main research issues: 1)the study of wireless network behavior of SCN in the HSR scenario;2)the analysis of data transfer performance of SCN in the HSR scenario;3)the concurrent utilization of wireless network resources based on SCN in the HSR scenario.The main contributions of this dissertation are:(1)For the first research issue,this dissertation measured,analyzed,modeled and predicted the wireless network behavior in HSR scenario.First,this dissertation performed a large amount of field measurement in a real HSR scenario.Through the statistical analysis of the measurement results the cyclical variation of wireless network behavior in HSR scenario was discovered.Then,this dissertation introduced a general reference model to mimic and re-produce such cyclical variation,and adopted the Hidden Markov Chain(HMC)to describe this reference model.At last,a behavior prediction algorithm was proposed based on the above HMC model,which can predict the behavior of wireless network in HMS scenarios with high accuracy.(2)For the second research issue,this dissertation focused on the modeling of data transfer performance over multiple wireless networks in the HSR scenario,and discussed the impact of harsh and unstable wireless environment.First,this dissertation defined the concept of “access component heterogeneity” and demonstrated the great behavior difference among heterogeneous wireless networks by showing the results of field tests in real HSR scenarios.Based on the field test results,the impact of wireless network heterogeneity on data transfer performance was analyzed.Then,a network communication model was introduced in which the data were transfered over multiple heterogeneous wireless networks.This dissertation derived the data transfer performance analysis model which used throughput as the performance indicator.The accuracy of the proposed model was verified through simulation and field test.At last,this dissertation further analyzed the impact of access component heterogeneity on data transfer performance,which showed that the behavior difference in delay had more negative effect than that in data rate..(3)For the third research issue,this dissertation proposed the “clustering first then cooperation” method,designed the wireless network clustering and cooperation scheme based on network behavior for HSR scenarios,implemented the proposed scheme in the Smart Cooperation Router,and had it tested on realistic high speed rails.First,this dissertation discussed about which behavior can be used as clustering indicators.Based on this discussion,the clustering indicators for High Data Rate Transfer Family(HDRTF)were determined.After that,this dissertation proposed a hybrid clustering method for HSR scenarios,and detailed how it worked in HSR scenarios.Then,a cooperation scheme of wireless networks was introduced for HSR scenarios,in which the forwarding path of a packed would be derived by consulting the mapping between services and transfer families,as well as by applying the forwarding policies inside a transfer family.The control of data forwarding was embedded in the user data flow.Finally,this dissertation introduced the SCN router which was based on the above clustering method and cooperation scheme.The modules of SCN were introduced from the entity domain and the behavior domain.The SCN router and corresponding clustering method and cooperation scheme was tested in real HSR scenarios,in which the values in the clustering method and the polices in the cooperation scheme were evaluated.The field test results showed that compared to traditional Internet architecture,the proposed method and scheme can significantly improve the throughput of HSR trains,as wall as the user experience.By the above studies of network access technologies and schemes based on SCN,this dissertation provides a novel solution for the Internet service research in High Speed Railway scenarios.