LTE系统中一种切换自优化算法研究

综合研究了长期演进切换算法中切换参数值、用户移动速度和负载均衡机制对系统掉话率的影响，提出了一种结合用户移动速度和负载均衡机制的切换自优化算法。仿真结果表明，如果用户的移动速度一定，且切换迟滞因子和切换触发时延小于一定阀值时，增加其中一个或两个参数值会导致系统掉话率增加。如果切换控制参数一定，系统掉话率随用户的移动速度增加而增加。针对移动速度为低速、中速和高速的用户，分别采用4，3，2 dB的切换参数较为合适。如果用户速度和切换参数均相同，采用负载均衡机制后，系统的掉话率明显降低。经仿真验证，与传统切换算法相比，采用结合用户移动速度和负载均衡机制的切换自优化算法可以有效降低系统掉话率，并使系统整体性能得到提升。

A handover self-optimization algorithm for LTE system

In this paper, the influence of the handover control parameters, the user''s movement speed and the load balancing mechanism are considered to study the rate of dropped calls of systems. Then we propose a handover self-optimization algorithms based on combination of user''s moving speed and load balancing mechanism. Simulation results show that if the user''s moving speed is constant and Time-to-Target/Hysteresis is less than a certain threshold, increasing one or both parameter values can increase the rate of dropped calls. If the control parameters are constant, the rate of dropped calls may increase with the user''s moving speed. For low, medium and high moving speed users, the optimal handover parameters are 4, 3 and 2 dB, respectively. If the user''s moving speed and the handover control parameters are constant, considering the load balancing mechanism can evidently reduce the rate of dropped calls. Simulation results show that compared with the traditional switch algorithm, using the handover self optimization algorithms based on combination of user''s moving speed and load balancing mechanism can effectively reduce the rate of dropped calls, then improve the overall performance of systems in this simulation system.