Design For The Metro Dedicated Wireless System

Among the metro communication systems,the dedicated wireless one is an important means by which the metro vehicles running at a high speed can communicate with the station management personnel,and is responsible for improving the running efficiency and ensuring the safety of the traffic and passengers.The wireless communication system of the subway is one of the most important subsystems of the communication systems,whose normal operation will play a vital role in ensuring the normal calls and data transmission between the train drivers and ground dispatchers if the wired communication transmission system in metro breaks down.It can guarantee the communication and data transmission between mobile staff and fixed personnel and thus ensure the normal functioning of the subway vehicles.The ultimate goal of the design of the dedicated wireless communication system is to ensure management functions of voice and data communication system,the effective coverage in full field and the improvement of communication quality.The design does not only play a decisive role in the performance of the whole wireless communication system and its price,but also have great impact on the expansion of the communication system in later phases of the metro project.Therefore,the cautiousness and optimization of the system design and the proper handling of the relationship between the current construction and future development are of great significance.This thesis begins with introduction of the functions of the wireless systems including communication,call,data transmission,system auxiliary,malfunction weakening and mobile user,etc.The network management terminal,the base station,the dispatcher station and wireless users machines are configured in the whole design.A t he same time,two base stations in the first period are connected into the systems,which is managed and operated independently through the function of the virtual dedicated networks.the design builds network through the networking of all the base stations,adds two carrier base stations,and covers the signal field on the platform and in the scheduling hall by antenna.The whole base station uses point-to-point star topology and has two sets of level 3 core switches which have host and backup.It connects all the wireless local area networks(LAN)of all base stations with the core router.In the control center it sets up a set of TETRA mobile switching control equipment,a set of cluster network management terminal and a set of redundancy configuration scheduling server for the sharing of line 8 and line 9 and 5 sets of dispatching terminals in the OCC scheduling hall.Each wireless LAN connects to the base station control center via the main line of the Ethernet,and E1 link.Each wireless LAN also interchanges core confidential information via a virtual dedicated network interconnection.After established the system’s overall frame,it can be verified by the calculation of line 9 fieldstrength cover through the village formula in order to ensure the rationality of the overall design.Then comes he design of the specific interface,the downgrade standby system.Based on the research,analysis and design for the application of the metro dedicated wireless communication system,the specific design scheme enables the dispatcher station communicate with all sections and each metro vehicle,station and wireless users within every metro depot.This thesis analyzes on the switching on of standby wireless communication system under the situation of exchange failure caused by emergency incidents and also designs the scheme of main/standby system switching,which makes the mutual switch between main and standby system possible in certain cases.In an actual metro wireless communication system,the interference among the wireless subsystem is an urgent problem which is also a big headache for wireless communication design.Therefore,this thesis makes elaborate analysis on the anti-interference in the metro wireless network subsystem design,especially on the same frequency interference and inter-modulation interference.It also includes the analysis and illustration on the system wireless controller redundancy,the switch of system vehicle-mounted equipment between head-stock and tail-stock,and the isolation and link between vehicle-ground wireless system and vehicle-mounted network.Reasonable system management,communication system,in particular,is essential for the normal and efficient metro operation.Thus,the thesis does a research for the main system configuration,the system self diagnosis,the application of network management and other functions like these.Hopefully,this thesis could make a difference to the coming establishment of urban metro wireless communication.