Communication And Coverage Performance Analysis Of Broadband Railway Mobile Communication System

With the rapid development of high-speed railways in recent years,the existing Global System for Mobile Communications for Railway(GSM-R)has been unable to meet the emerging demands for broadband services.At present,the deployment of the broadband railway dedicated mobile communication system(5G-R)has been started,which adopts 5G technology to support the high-speed and reliable information transmission of the intelligent railway train-ground communication system.5G-R is different from the traditional GSM-R network and public 5G network.Therefore,it is necessary to conduct corresponding research and explore the deployment suitable for railway scenarios before the large-scale commercial application of the future broadband railway mobile communication system.The future railway network needs to achieve large capacity and high coverage quality.In this background,this thesis establishes the 5G-R chain interlaced redundant coverage system model to quantify communication performance and coverage performance of the broadband railway system under different overlapping depths.The main research contents of this thesis are as follows:Based on the characteristics of chain coverage and interlaced redundant coverage,the communication performance of 5G-R system is deeply analyzed.It focuses on the impact of intercell co-channel interference on the performance of cell subscribers,especially edge subscribers.Firstly,the distribution of the downlink subscriber multi-carrier signal-to-interference and noise ratio in 5G-R is obtained based on the approximate and mapping methods.Then,the signal-to-interference and noise ratio distribution is used to derive the closed expressions of cell single-subscriber outage probability and capacity.This thesis also establishes the performance analysis model related to cell edge capacity and overlapping depth,which can efficiently evaluate the impact of co-channel interference on cell edge performance.Combined with the evaluation results,it can narrow the performance gap between subscribers to ensure the stability of service transmission.The base station failure factor is introduced into the 5G-R system coverage performance evaluation,and it deeply analyzes the system coverage reliability affected by the long-distance communication link loss.Firstly,path loss superimposed shadowing models are established in three scenarios: no base station failure,center base station failure and simultaneous failure of the center base station and a neighboring base station.Then,the model is used to derive the closed expressions of the cell coverage outage probability in different scenarios.By combining base station failure probability with cell coverage outage probability,the thesis establishes the performance analysis model related to cell coverage probability and overlapping depth,which can achieve the quantitative evaluation of system coverage reliability.Numerical analysis results show that deep overlapping coverage can significantly improve the system coverage reliability,but it will also introduce serious intercell co-channel interference and reduce the capacity of the cell edge area.Therefore,the main purpose of this thesis is to explore how to set the redundant coverage area of adjacent cells to obtain the optimal base station deployment strategy by balancing communication performance against coverage performance in the chain coverage and co-frequency networking architecture of 5G-R.Relied on the previously established performance analysis models,this thesis takes overlapping depth as the optimization variable,and further develops the optimal base station planning under different conditions through the joint optimization.The research results are full of good theoretical guiding significance for the network planning and base station deployment of the future broadband railway mobile communication system.