Study On LTE Handover Technology In CBTC Systems

Nowadays,modern rail transit plays an increasingly important role in the development of a city.More and more cities are developing rail transit.For rail transit,CBTC is the brain and core of rail transit.It can not only guarantee the safe operation of the train,reduce the number of failures and enhance the passenger's travel experience;It can also shorten the operation interval between trains,improve the operation efficiency greatly,guarantee the high stability of business transmission,provide auxiliary decision-making for fault occurrence,and continuously optimize the command and dispatch functions.LTE is the fourth-generation mobile communication technology.At the time of design,the transmission performance of 350 km per hour is considered,and the perfect business priority scheduling strategy(supporting multi-service with different priority levels),real-time performance and high throughput rate are considered.It fully meets the demand of the real-time transmission of the information of the urban rail transit express(the train speed of 120km/h or above)and the business priority of the integrated carrier.At the same time,LTE also has a number of core independent intellectual property rights international communication standard technology in our country,already in China large-scale commercial,has a relatively mature industrial chain.In this context,the system architecture and key technologies of LTE are introduced,and the switching mechanism of LTE is studied.Through the analysis of CBTC switching requirements,including CBTC composition,the influence of CBTC environment on switching,and CBTC switching performance requirements,etc.Finally,Improved Grey Verhulst model is used to predict the Reference Signal Receiving Power(RSRP)values from two Radio Remote Units(RRU).Compared with traditional Verhulst model,improved Grey Verhulst model can optimize parameters to eliminate the inherent errors in data sequence prediction.The handoff decision is performed based on the predicted RSRP values.By simulation,the algorithm can meet the performance requirements of CBTC switching In the environment of free space and leaky coaxial cable,LTE handoff delay and ping-pong handoff can be effectively reduced.