Research On TD-LTE Handover Technology Under The Environment Of High-speed Railway

With the rapid development of China’s high-speed railway, its operating scale and speed constantly upgrading, effectively easing the flow of China’s population travel difficult problem. But with the upgrade train speed, the current railway broadband wireless communication system there is frequent handover with high rate of dropped calls, serious impact on the user experience. Therefore, how to improve the performance of the railway broadband wireless communication system to become the most important issue China’s three major telecom operators must be addressed. The TD-LTE communication system with a flat network architecture, high data rate, low latency characteristics that make TD-LTE has a good prospect in the high-speed railway broadband wireless communication system. Handover technology as one of the most important technologies TD-LTE communication system, the performance of the algorithm directly affects the handover network quality of service communication system.In this paper, TD-LTE handover technology theory-based, system-level simulation platform based on LTE LTE-Sim tool for the study of high-speed railway environment to start TD-LTE handover technology research. First TD-LTE network architecture and protocols, as well as the concept of cause and classification of switching were discussed, detailed analysis of the TD-LTE handover algorithm signaling processes; then simulation system-level simulation platform based Institute for LTE-Sim on this topic required simulation environment, measurement reporting module, switching algorithm module design; switching algorithm to trigger events based on the traditional A3performance evaluation. Found by simulation based on traditional A3triggering event to switch the switching algorithm has excellent performance at low speeds, but in an environment with a high-speed packet loss rate and the failure rate of the link connection, TD-LTE can not satisfy the high-speed communication systems and services environment quality.To solve these problems, this paper based on A3event triggers an optimized switching algorithm, which is based on statistical A3event switching algorithm that principle is a statistical reference signal received power value reaches the switching decision threshold of the number of thresholds, when satisfied switching rules statistical number reached statistical thresholds can be switched. The simulation found that in the event of statistical switching algorithm A3at high speed railway environment, faced with different speeds have good switching performance, reaching the network quality of service requirements TD-LTE communication system. For high-speed high-speed railway scene environment, this paper also proposed switching algorithm based on GIS TD-LTE, the principle of the algorithm is based on geographic information of the cell first generates a chain of neighbor cell lists networks and scientific design reference switching switching switching position and the reference point to when the client reaches the reference point switch will perform cell switching. A comprehensive GIS-based advantages of TD-LTE handover algorithm A3event triggers based statistical switching algorithm for switching algorithm based on GIS TD-LTE has been proposed to improve the pre-load of the target cell-based TD-LTE switching algorithm preset reference point coordinate according to a pre-bearing GIS. Thus, by way of a pre-bearing energy efficiency to reduce the switching time, which also ensure the success rate of handover. Meanwhile found through simulation, RLF probability of the algorithm, packet loss rate of two switching performance is much better than the GIS-based TD-LTE handover algorithm A3event triggers based statistical switching algorithm.