Dynamic Load Balancing Algorithm Based on Traffic and Sojourn Time in Heterogeneous Hierarchical Wireless Networks
异构分层无线网络中基于业务和逗留时间的动态流量均衡算法

Efficient load balancing algorithm can be used to serve more mobile stations in the heterogeneous hierarchical wireless networks. The existing load balancing algorithms, which were designed for homogeneous networks, are not applicable to the heterogeneous wireless networks. This paper proposed a dynamic load balancing algorithm based on traffic and sojourn time for heterogeneous hierarchical wireless networks. Firstly, based on user mobile model, the sojourn time of each mobile station in cells was calculated, then the number of transferred ongoing non-real-time 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 can 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.