Research On The Coverage Scheme Of High-speed Rail LTE Wireless Network

In recent years,the high-speed rail is developing rapidly in China and the world.The mileage of high-speed rail has reached more than 30 thousand kilometers at present,which is still with rapid growth as well.With the large and longtime ride of high speed rail,frequent mobility and the demand for information construction of the railway itself,the communication demand between the high speed rail and the ground is becoming more and more intense.The LTE system has provided the best technology of rail broadband wireless communication with the characteristic of large bandwidth and short time delay.At present,the designed speed of high-speed rail has reached 350km/h,but the rapid movement of trains will inevitably bring the varied problems of Doppler frequency deviation,frequent handover and high penetration loss.For 4G,it will cause the bad perception of users because of higher frequency.How to ensure users access and handover successful rate in the scenario without less than 350km/h is the main purpose of this paper.At the same time,the features of high speed rail coverage have also put forward more stringent requirements for the solutions of LTE wireless coverage,such as complex scene,fast running speed,and concentration of business demand.In this study,we mainly focus on how to cover complex scenes and varied business demands,and we`ve worked out a solution of refining varied scene.The main work and results are as followed.1.In view of the Doppler frequency deviation that is brought by the fast train running speed,the correct demodulation and decoding of the uplink data is ensured by the AFC algorithm in the baseband unit plus the ICI correction in the symbol.2.Aiming at the problem of large penetration loss of train body,we choose the location of base station reasonably,control the incidence angle,and find the balance point between investment and coverage effect.3.In view of the impact of frequent handover on service continuity,the multi RRU co cell scheme is adopted,and plan the overlap area reasonably.Then,handover times and the handover latency can be reduced as much as possible to make the service continuous.4.For complex and diverse scenes,the different coverage strategies and models are adopted to get well coverage effect.5.According to the characteristic of traffic burst,the reasonable capacity planning is carried out.The peak throughput rate of the train is obtained through the high speed railway passenger volume,the user quantity and the service model,so as to select the appropriate equipment configuration to cope with the traffic burst.6.Express designed speed is getting faster and faster.At present,the highest experimental speed has reached 490km/h,and the 5G era is coming soon.It will bring more challenges to the wireless coverage of high speed rail,and we have to continue to explore and study.