轨道交通无线通信系统的引入与场强覆盖分析

无线通信不仅应满足城市轨道交通内部专用运营管理和业务需求,而且应提供公共移动通信服务,方便人民群众。那么,除了必须设置专用无线通信系统外,如何引入民用无线通信系统、如何避免相互影响以及系统设备共用等问题的解决,将保证无线通信质量的要求,避免无线通信系统的无序、重复建设和浪费资源。     

Locating fixed roadside units in a bus transport network for maximum communications probability

A key issue in solving the difficult bus-bunching problem is being able to have reliable information about the location of the buses in the network. Most advanced public transport systems have buses with GPS devices, but the problem remains of how to send reliable information from the buses to the control unit, particularly when the density of buses is low, but there are high communications reliability requirements. As a solution, we study locating roadside units (RSUs) along the route. The buses, together with the RSUs, form a linear vehicular ad-hoc network (VANET). The RSUs are deployed so to maximize the probability of a vehicle communicating with an RSU in at most two hops. Previous studies on RSU location never took into account two hops, a conceptually different type of network. Rather, they consider that a vehicle is able to communicate only directly to an RSU (one hop), which is a well-known Maximum Covering Problem, in which one of the parties is always immobile, similar to a mobile phone network. Oppositely, our method solves the problem in which two of the intervening parties are mobile and communicate with each other, not possible to solve as a Maximum Covering Problem. We estimate the probability of a vehicle accessing successfully an RSU either directly or through the relay of another vehicle. This probability is later embedded in an integer programming formulation that optimizes the RSU locations for maximum communications likelihood.Numerical examples show that the connection probability is strongly dependent on the coverage ratio of the transmitters and receivers and relatively independent on the vehicle density on the network, when densities are low. Results also show that it is possible to find some cost-efficient solutions which result in a smaller number of RSUs located while assuring a connection probability of 0.9 or higher.     

室内无线分布系统的规划

室内信号的覆盖问题关系到移动通信服务的质量。根据室内无线分布系统组成，合理规划室内站分布，并结合实例提出几种解决方案，并对室内分布系统的优化提出建议。     

青藏铁路GSM-R无线网络场强覆盖测试探讨

从工程角度探讨青藏铁路GSM-R网络场强覆盖测试的重要性和必要性，着重从数据采集方法、采样间隔与同时采集的频点数之间的关系，以及数据处理方法等方面进行了阐述。     

GSM-R网络小区半径和重叠区规划

随着GSM-R网络在中国铁路的广泛应用，网络预规划作为网络建设的一个重要步骤，得到了重视。结合铁路通信的特点，在高速和普速环境下，采用Hata模型对典型的5种地理环境进行建模，并结合链路平衡预算，给出小区覆盖半径的规划方法，同时，利用同频干扰与小区重叠区的关系，给出小区重叠区的规划方法。     

城市轨道交通线路高架区间无线通信方案浅论

城市轨道交通高架区间场强覆盖弱区,通常可以采用架设天线作为辐射源的空间波覆盖方式及敷设漏泄同轴电缆作为传输线和分布天线的覆盖方式加以解决,结合区间中继设备又可衍生出多种解决方案。重点讨论基站天线覆盖方案、基站天线+直放站天线方案和敷设漏泄同轴电缆方案。     

地铁公用无线通信系统组成与信号覆盖施工要求

介绍地铁公用无线通信系统的组成,并对信号覆盖控制的施工提出要点。     

城际铁路隧道移动公网覆盖工程方案研究

以广珠城际铁路凤凰山隧道引入移动公网覆盖的需求为基础,从覆盖预测、设备布置、LCX挂设、干扰分析等四个环节出发,提出以泄漏同轴电缆为主的公网隧道无线覆盖解决方案。     

厦门BRT链接线服务范围延伸作用研究

BRT作为一种可持续的城市公共交通模式,它所具有的快速性、灵活性和成本效应对国内城市尤为适合.基于BRT的优点及厦门市交通现状,厦门市BRT一期工程及其链接线于2008年9月初建成并投入运营.本文主要针对厦门市“BRT+链接线”模式,通过服务半径及覆盖面积的计算,分析BRT链接线对BRT主线服务范围的延伸作用及设置BRT链接线的相关意义.     

铁路并线区段GSM-R系统无线覆盖方案探讨

以京沪高速铁路和沪宁城际铁路为例,在GSM-R系统网络承载列控应用的前提下,针对并线区段的各种地理情况就无线覆盖、频率规划和容量规划等进行探讨,并结合软件仿真结果提出了铁路并线区段GSM-R系统的无线网络规划和优化的解决方案。