The Research Of Handover Algorithm Of Position-Power Joint Decision For High-speed Railway Communication

In recent years,many countries around the world regard the development of high-speed railway(HSR)as an important means to implement sustainable development strategy and adjust the structure of transportation in the field of transportation,and the construction of HSR is also suitable for China’s basic national conditions and characteristics of passenger flow.In the operation process of HSR,railway wireless communication system provides many services for its normal operation,including but not limited to railway safety guarantee business,railway transport management business,railway Internet of things business and passenger information service business.In public network cellular mobile communication,over zone switching is a measure to ensure the uninterrupted communication of mobile users in mobile state and prevent communication interruption.In the case of HSR with high speed,over zone switching is the key technology to guarantee the reliability of communication links and provide seamless communication.With the continuous development of HSR business,the increasing speed of high-speed trains,the increasing number of passengers,the growth of user communication service types and 5G mass equipment access put forward higher demands for HSR mobile communication system.Using the efficient over zone switching technology can not only reduce signaling overhead,save energy and protect environment,but also improve system performance and maintain high throughput.How to adapt to the complicated channel environment of HSR and improve the success rate of handoff is a hot issue in the research of handoff algorithm.This dissertation analyzes the research status of crossing zone switching algorithm at home and abroad,studies the switching algorithm of joint decision of position power,analyzes the advantages and disadvantages of the algorithm,and puts forward the improvement scheme and the next research strategy.The main work is as follows:(1)In the HSR environment,an over-zone switching algorithm based on joint position power decision is proposed.The optimal switching band is obtained by using the channel model and measurement information,and the location information is simplified and the switching process is optimized by using the one-way moving characteristics of trains.Considering the correlation between the decision errors of vehicle-mounted multiple relay nodes,the cost function was constructed to screen the optimal prediction parameters,and the weighted statistical linear regression method was used to predict and correct the decision errors.(2)For specific low SNR scenarios,an auxiliary switching scheme for power adjustment is proposed.Channel recognition steps are added in the measurement stage of over-zone switching channel,and the signal-noise power ratio of the current channel and the channel of the same frequency cell in the adjacent area are monitored,and channel conditions are identified to select different switching strategies.When the signal noise power is high,the joint decision switching algorithm with short trigger time and low computation cost is adopted,and when the signal noise power is low,the power adjustment scheme is adopted.The concept of signal differentiation is proposed and the definition of signal differentiation is given by using three kinds of dynamic functions.The algorithm performance is compared by simulation,and the inverse proportional function with better comprehensive performance is selected to improve the switching success rate and communication quality by power adjustment method.