高速铁路掉话优化切换方案仿真

Simulation of Handoff Scheme Optimization for Dropped-call in High-speed Railway

为减少切换次数且在及时完成切换的情况下优化掉话概率性能,提出基于双移动中继切换算法。双移动中继器分别位于列车的前部和后部。当由移动中继测量的相邻基站信号强度超出服务基站信号强度一个滞后水平时,将执行切换。算法考虑了列车前后移动中继接收信号的强度差,对切换过程进行分析。平均切换次数和平均掉话次数被用作性能指标。数值仿真结果表明,基于双移动中继算法具有可行性。将所提算法与其他两种算法进行了切换性能实验比较。一种是基于绝对和相对信号强度测量,另一种是基于单个移动中继,发现该算法在对数正态衰落环境下的性能优于其他两种算法。

To reduce the number of handoffs and optimize the performance of dropped-call probability in the condition that the handoff can be completed in time,a novel handoff algorithm based on double mobile relays is proposed in this paper.The double mobile relays are positioned at the front and the rear of a train,respectively.The algorithm performs handoff when the signal strength of the adjacent base station measured by the mobile relay exceeds that of the serving base station by a hysteresis level.The proposed algorithm analyzes the handoff process considering the received signal strength difference of the front and the rear mobile relays of the train.The average number of handoffs and average dropped calls are adopted as performance indicators.Numerical simulation results are presented to demonstrate the feasibility of the double-mobile-relays-based algorithm.The proposed algorithm compares the handoff performance with two other algorithms.The one is based on absolute and relative signal strength measurements,the other is single mobile relay.It is found that the proposed handoff algorithm performs better than the other two algorithms in log-normal fading environment.