异构分层无线网络中基于逗留时间的动态流量均衡算法研究

Research on sojourn-time-based dynamic load balancing algorithm in heterogeneous hierarchical wireless networks

为使异构分层无线网络能服务更多的移动用户,提出了一种基于逗留时间的动态流量均衡算法。该算法首先根据用户移动模型计算其在小区内的逗留时间,然后基于小区呼叫到达率和重叠覆盖小区的流量状态来确定一个周期内呼叫转移的数量,最后依据逗留时间门限值将重负载小区中满足条件的呼叫转移到轻负载的重叠覆盖小区中。为降低切换呼叫掉线率,还对异构网间的呼叫切换策略做了改进。仿真实验结果表明,本算法在新呼叫阻塞率和切换呼叫掉线率等性能指标上比传统方法有显著的提高。

In order to serve much more mobile stations in heterogeneous hierarchical wireless networks, a dynamic load balancing algorithm based on sojourn time was proposed. Firstly, based on user mobile model, the sojourn time of each mobile station in cells was calculated, then the number of transferred ongoing calls per load balancing period was counted according to the new calls arrival rate of overloaded cell and the workload states of overlapping cells. Finally, those ongoing calls with longer sojourn time than the threshold were swithched from overloaded cells to overlapping heterogeneous under-loaded cells, which could balance the system workload. In addition, in order to decrease the handoff call dropping probability, the vertical handoff schemes between different wireless networks were improved. Simulation results show that the proposed dynamic load balancing algorithm performs much better than existing algorithms with respect to the blocking probability, dropping probability and etc.