高速铁路LTE-R改进切换算法的研究

针对高速铁路中LTE-R越区切换对切换时延和切换成功率的严格要求,以3GPP TS 23.401协议中的A3事件判决公式为基础,利用滤波中的测量周期Tm对触发时延进行计算,并结合列车的运行速度,对传统切换算法进行改进。通过对改进算法进行仿真,得到最佳切换参数。最后对两种算法采用相同的基站布置进行仿真比较,得出传统算法在列车运行速度超过205 km/h时,无法满足我国无线通信系统对越区切换成功率99.5%以上的要求,而改进后的算法在速度达到400 km/h时,切换成功率为99.6%,仍满足此要求。

Research on LTE-R Improved Switching Algorithm in High-speed Railway

In order to meet the strict requirements of switching delay and switching success rate for LTE-R handoff in high-speed railway,the triggering delay is calculated by using the Tm of measurement period in the filter based on the A3 event decision formula in 3 GPP TS 23. 401 protocol,and the traditional switching algorithm is improved corresponding to the running speed of the train. The improved algorithm is simulated and optimal switching parameters are obtained. By simulating and comparing the two algorithms with the same base station layout,it is concluded that the traditional algorithm cannot meet the requirements of the wireless switching system with the success rate of more than 99. 5% of the handover in China when the train running speed exceeds 205 km/h; while the improved algorithm can still meet the requirement with the switching success rate of 99. 6% even the speed reaches up to 400 km/h..