The Optimization Design And Implementation Of The High-speed Railway Network Coverage Based On The TD-LTE System

As China entered the high speed railway (HSR) age, the travelers are deeply attracted by it for its fast, low-cost and convenient service.Increasing number of people choose HSR to replace other modes of transportation. According to the high-speed environment of the radio waves propagation, the supporting wireless network must be improved.With the maturity of 4G technology, the TD-LTE fourth generation communication system, which is dominated by China, is about to be put into commercial use. This paper focuses on the implementation of TD-LTE signal system for high-speed railway network coverage problem. Due to the high speed of the train movement and the poor channel environment, the handoff frequency and link quality are decreased. Therefore, it is needed to improve the communication quality of high speed railway, which is suitable for high speed mobile environment.In this paper, the problems related to signal coverage and optimization of high speed rail network are studied. The technical problems and solutions for the quality of mobile communication are mainly included. The optimization principle and method of Gao Tie network are focused on, and the optimization of TD-LTE network in Dalian section is described. This paper studies from the wireless radio waves propagation characteristics under the environment of high speed, analysisies and verifies the physical phenomenons such as fast fading, Doppler effect, penetration loss that hinder the wireless communication, and expounds the demanded points of the the technical indexes. Then this paper discusses now commonly used in network scheme and network optimal policy, and will they do the contrast between, demonstrates the different environment needs the different network scheme.The factors that affect the quality of mobile communication in high speed rail are the Doppler frequency shift and the handoff. The Doppler frequency shift will result in the error of receiving system signal, and the orthogonality between the sub carriers of the OFDM system, resulting in severe ICI. Coherent demodulation, differential coherent receiver, diversity reception and so on, the Doppler frequency shift estimation and suppression technology can eliminate the adverse effect of the Doppler shift. The handover problem is mainly caused by the high speed rail train running speed is too fast and the switch is not timely, the general, can be increased by increasing the overlap between adjacent cells and the optimal system parameters to solve the problem.The link budget and networking scheme are the key issues in the planning and design of high speed rail network. Through the research of the model selection and calculation principle in different scenarios, the paper lists the business model and the uplink budget of the high speed rail TD-LTE network design. Comparison of public and private two networking modes, the networking scheme of High-speed Rail along the network selection and coverage strategy. Finally, to Dalian high TD-LTE network optimization project as an example, in dual carrier pilot frequency coverage and system parameters optimization adjustment of a series of optimization scheme after the implementation, Dalian high iron TD-LTE network indicators were significantly increased and achieved good optimization effect.