Reasearches On Policy Language And Policy Engine In HSR-REM System

The increase of train speed and appearance of new railway carriage bring us efficiency and comfort. At the same time, requirements on communication service types and quality in the high-speed environment are increasingly high, which put forward higher requirement for railway wireless communication. Currently, the high-speed railway mobile communication system is faced with four challenges:completely closed steel structure of train resulting in poor signal penetration, high-speed moving resulting in frequent handover, Doppler shift caused by high mobility, and frequency band scarcity. The thesis focuses on the problem of insufficient bandwidth.The motivation of DARPA’s NeXt Generation (XG) communication program is the spectrum shortage and deployment difficulty that is quite similar as what we are faced with in high-speed railway mobile communications. The spectrum sharing company’s test on a series of spectral occupancy shows that most of the static assignment spectrum are unused in space and time, which leads to low utilization of spectrum. So the XG program proposes opportunistic spectrum use to increase spectrum availability. Further more, the XG program has embraced a solution for spectrum management scheme based on policies to achieve opportunistic spectrum use. Spectrum management method based on policies has the following advantages:radio behavior can quickly adapt to a changing situation; policies are platform independent; decouples policy definition, loading, and enforcement from device-specific implementations and optimizations; extensibility etc. The thesis will apply the concepts based on policies to high-speed railway communications.The organization of the thesis is as follows:the second chapter gives the design of high-speed rail engine framework based on XG radio architecture to establish the overall concept, based on which, the basis of the policy-based method is introduced and the reason that selecting CoRaL as policy description language in high-speed railway communications is elaborated; the third chapter describes the CoRaL syntax in a bottom-up fashion, starting with the smaller building blocks, then introduces statements and rules, and ending with entire policies, ontologies, requests; fourth chapter discusses the design of high-speed rail communication ontologies and policies; the implementation of CoRaL parser and analysis of reasoning of high-speed rail communication policies are provided in Chapter5. Test and analyzing results are given to verify the feasibilities of high-speed rail policies and the high-speed rail policy engine.