| With fast iteration of communication technology and rapid construction of domestic communication network,4G is replacing 3G becoming the mainstream communication technology in China. High-speed rail is developing rapidly in our country as well as worldwide.Its operation mileage has reached 30,000 kilometers, and it showed a rapid growth trend. More passengers choose high-speed rail as their primary transportation tool.Based on the rapid development of railway information technology construction,the communication quality on high-speed rail becomes more and more important. Rely on the high data rate,broad bandwidth,short time delay and high spectrum efficiency, LTE technology is becoming the best technical way for high-speed rail wireless communication network coverage.The complicated scenes, the extremely fast speed and the mutational communication demand propose more stringent requirements for high-speed rail LTE wireless communication network coverage. The main significance of this essay is to achieve perfect 4G network coverage on high-speed rail,meanwhile to provide the passengers with wide broadband in train compartments to meet their communication needs. First, to meet the IT construction needs of the rail system.The staff can access to train running log anytime anywhere to enhance security capabilities. Secondly, to achieve remote operation, reduce labor intensity, saving operating and maintenance costs, and to improve reliability. Third, to monitor the video images of hundreds of trains at the same time, obtain the videos of the train,make sure the monitoring and scheduling of the train, and to meet the security and protection needs. Finally, to provide the passengers fast "China speed", satisfy mobile office requirements,access to the Internet,share travel informations, provide passengers with a wealth of interactive entertainment resources. In the future, "high-speed rail travel + high-speed Internet" will become two basic things for Chinese.The complicated scenes, the extremely fast speed, the closed compartments and the small station spacing led to three main issues: 1, the Doppler frequency shift problem; 2, high-speed switching and re-election problem; 3, high penetration loss problem. In this essay, solutions are mainly divided into two parts:the 1st part is the algorithm for the high-speed railcharacteristics; the 2nd part is to develop communication network analysis and solutions scheme for high-speed rail complex scenes.The first part is the algorithm for the high-speed railcharacteristics.This essay explores three algorithms: 1, e Node B uses AFC algorithm. Initial corrective and continuous corrective can correct the Doppler shift problem;2, e Node B is configured as open-loop adaptive MIMO, in order to resolve high-speed switching and re-election issue; 3, Cell merge will expand the cell range.It can reduce terminal switching and enhance the downlink coverage,so as to solve the high penetration loss problem. These three algorithms provide basic technical supports for the communication network coverage solution scheme.The second part is communication network analysis and solutions scheme for high-speed rail complex scenes. The research is focused on the multi-scene network planning and coverage shceme, equipment selection, network specifications, site layout, overlapping coverage area planning, station spacing planning, 4T4 R enhance coverage programs, capacity planning and high-speed rail cell parameters planning. The essay is a complete LTE high-speed rail networking coverage solution scheme. According to the Beijing-Tianjin high-speed rail test examples, overall performance has been improved: downstream throughput increased 14%; network connection rate reached to 100%; network handover rate achieved 100%. The research proves that the planning can ensure the perfect high-speed 4G network coverage during fast moving with the speed is not less than 350 km / h, and ultimately provide a great user experience. |
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