Reserch On Fast Handover Algorithm And Quality Of Service Guarantee For TD-LTE High Speed Railway Networks

The rapid development of High Speed Railway(HSR)makes the wireless communication system be confronted with new opportunities and challenges nowadays.The development and popularity of new services and intelligent terminals are entering their new stage of acceleration.That has put forward higher requirements for broadband wireless communication system in HSR environment.Satisfying the increasing demand for communication of passengers becomes a trend that network design has to adapt to.The handoff performance of mobile networks is the key to guarantee the quality of wireless links.However,mobile terminals have to face a series of problems when being used in high speed railway environment,such as the significantly increased communication interruption brought by frequent hard handover,and incremental probability of radio link failure caused by excessively shorter time of passing through the overlap ragion.Supported by National Science and Technology Major Project,this dissertation does some research on the HSR broadband wireless communication system.Combining with the special network structure along HSR line,optimized handover schemes are proposed in this dissertation.The results are listed as follows.Background and significance of the research work are introduced.The handover process of TD-LTE communication systems is summarized,and both overseas and internal research situation are analyzed.Special condition of the HSR networks is explicated,and existing problems of handoff scheme for HSR wireless communication are explained,aiming to illustrate the necessity of research on handover and signaling.The simulation platform is established.This part focuses on the generation of reference signals and the use of channel matrix.On this basis,a complexity reduced method of iterative linear channel estimation for time varying channel is proposed,and the performance is emulated.After that,measuring method of Reference Signal Received Power(RSRP)and Reference Signal Received Quality(RSRQ)are explained for this platform.In the end,simulation results show the influence of speed and SNR on RSRP and RSRQ.Handover procedure and decision algorithms are summarized.The problems of LTE handover technology are analyzed combined with the HSR environment characteristics.Numerical analysis and simulation are utilized on the performance characteristics study of LTE handover technology,which lay the foundation for the following research.Location information assisted handover algorithm for TD-LTE system is proposed.Several schemes for selecting the handover location between two cells are proposed,including following ones:The first scheme utilizes differences of RSRP between source and target eNodeB and block error ratio;the second one uses differences between the throughput before and after handover process.The user experience influenced by frequent hard handover is also considered.For high speed environment,a handover scheme based on main-backup vehicle mobile terminals is proposed.The principle and execution steps of the algorithm are explained,and its performance characteristics are numerically analyzed.Finally,simulation and calculation are used for indicating the advantage of the proposed scheme.