Research On Handover Technology Based On Distributed Antenna In High Speed Railway

With the rapid development of high-speed railways in China,there is an increasingly higher requirement of passengers for wireless communication technology between the train and ground..The existing GSM-R systems have great limitations in many railway communication applications such as channel capacity,frequency bandwidth and so on.It can no longer meet the needs of the future railway development of two-way,real-time and large capacity.LTE-R,as the evolution of GSM-R,LTE-R is a new generation of railway-dedicated wireless communication technology.It has great performance improvement in spectrum efficiency,network architecture and small interference,it can not only meet the needs of people for wireless communication,but also improve the quality of communication to a large extent.It has become a research hotspot of high-speed railway wireless communication.has become a research hotspot of high-speed railway wireless communication.In the high-speed railway communication system,handover is the key technology to ensure the continuous communication of trains in high-speed operation.The antenna distribution along the railway will also be studied as the basis of switching technology,which can guarantee the channel capacity in wireless communication links.The current study explores the key technologies of LTE-R,namely distributed antenna technology and handover technology respectively.Firstly,for the special communication scenario of high-speed railway,after analyzing the antenna deployment problem along the railway,an antenna deployment scheme more suitable for high-speed rail environment-distributed antenna system is proposed.The channel capacity of the distributed antenna system is analyzed.When the channel state information at the transmitter is known and unknown,the water injection power algorithm and the average power algorithm are used respectively to distribute power of the channel capacity.Considering the structural characteristics of the high-speed railway environment.Channel state information at the transmitter is generally a known situation,and the high-speed rail environment is mostly a LOS direct path,and the scattering paths are few.and the water injection power algorithm is adopted.Secondly,the train will face the problem of handover in high-speed operation.Based on the proposed distributed antenna scheme,an optimization scheme of handover algorithm based on distributed antenna is proposed.Referring to the constructed system model diagram,according to the running speed of the train.Based on the RSRP and RSRQ switching algorithm,considering the problems of signal fading in train operation,the hysteresisthreshold of switching is adjusted dynamically,and compared with the traditional switching algorithm.Finally,the improved algorithm optimization scheme,was constructed by matlab simulation platform,and the theoretical verification and simulation results were analyzed.Among them,the algorithm optimization scheme proposed in this study has a significant decline in terms of outage probability,handover failure probability,average number of handovers and other indicators.However,the switching access probability and handover success rate are improved,and the communication quality is improved.