Abstract: First this paper estimates the bandwidth demand of the vehicle-ground communication information for the GoA4 level operation of urban rail transit,  showing that 4G vehicle-ground integrated communication system of urban rail transit based on 1.8 G band LTE-M technology cannot meet the service demand, especially the uplink throughput capacity. Then it briefly introduces 5G technology, expounds the great potential and limiting factors of 5G mobile communication system used in vehicle-ground integrated communication for urban rail transit, and studies the feasible 4G and 5G hybrid networking mode to provide high-speed, low delay and high reliability solution for vehicle-ground integrated communication system of urban rail transit by considering the service level, technology development status and investment factors. At last, the paper puts forward the prospect of solving the existing problems in the future.

Key words: vehicle-ground communication, 5G, carrying demand, GoA4, networking

摘要： 首先估算城市轨道交通GoA4级运行的车-地通信信息带宽需求，说明基于1.8 G频段LTE-M技术的4G城市轨道交通车-地综合通信系统，无法满足服务需求，尤其是上行吞吐能力。然后简要介绍5G技术，并阐述5G移动通信系统用于轨道交通车-地综合通信的巨大潜力和限制因素。接着综合考虑服务水平、技术发展现状和投资因素，研究可行的4G和5G混合组网模式，为车-地综合通信提供高速、低延时、高可靠性的解决方案。最后，就尚存在的问题，提出未来解决方向的展望。

关键词: 车-地通信, 5G, 承载需求, GoA4, 组网