Research On Smooth Evolution Technology Of Railway Intelligent Services

The GSM-R system is adopted in China’s railway communication at this stage.As the construction of high-speed railways is rolled out,new business demands are increasing rapidly.Subject to its own frequency and mode,GSM-R as a narrow-band communication system can’t provide wideband data flow services,with the contradictions between its lower service carrying capacity and higher requirements for the railway informatization construction becoming increasingly prominent.As a result,the evolution of the railway communication system into the LTE-R has already been inevitable and urgent.At present,the International Union of Railways(UIC)and some authoritative organizations have not developed the specification and agreement on how to realize the intelligent operation of existing railways based on the LTE-R.As the characteristic business of railway communication,intelligent services play an important part in the safety operation,dispatch and command of railways.For instance,the functional addressing in intelligent services can effectively simplify the call flow between train dispatchers and train drivers,improving the efficiency of railway operation.So the research on the evolution technology of intelligent services can not only guarantee the normal operation of the railway under the co-existence condition of double-layer networks,but also provide references for the construction of the next generation railway intelligent network and the development of new businesses.Based on a national key program "Research on Key Technology in the Next Generation Mobile Communication for the Railway---Research on Key Technology in the Next Generation mobile Communication System for Railway Special Communication Services",the paper mainly conducted a research on the smooth evolution of railway intelligent services.The main works in the thesis are as follow:(1)By analyzing the cluster architecture,interface definition,and call setup process of a cluster communication system based on MCPTT(Mission Critical Push To Talk),combined with the law of railway communication development in the future,three different stages of the transition experience in intelligent networks are proposed:The SCP only supports the CAP interface,the SCP upgrade supports both SIP and CAP,and supports only the SIP protocol.The network architecture of the intelligent network and the call flow for interconnection and interworking are studied separately for each period.(2)Based on the LTE-R intelligent network architecture,combined with the basic call state model of the intelligent network,the principle of using the IM-SSF(IPMultimedia Service Switching Function)to trigger the intelligent network to realize the railway intelligent service is mainly studied.The functional addressing,location addressing,location-based call restriction,call restriction based on MSISDN number service implementation methods and signaling flow were designed separately.The SIP message parameters under different services were studied and examples given.The elements of the IDP message in the CAP protocol are generated after the IM-SSF protocol conversion in the function addressing service,and a method for realizing the call restriction based on the MSISDN number based on the MCPTT configuration file is proposed.(3)In the end,the laboratory environment is built to test the function number registration,functional addressing and location dependent addressing,and conducting an analysis of the SIP signaling captured in the process of the test.As a result,the rationality and feasibility of the intelligent network construction scheme are verified to ensure the smooth evolution of intelligent services.