Research On Load Balancing Algorithms In Heterogeneous Wireless Networks

One of the main features of next generation communication system is the convergence of heterogeneous wireless networks. The hot research topic in heterogeneous wireless networks is how to take advantage of each access network and equitably allocate network resources, in order to realize the optimum utilization of radio resources. As a major part of radio resource management in heterogeneous wireless networks, load balancing technologies can improve radio resource utilization, prevent system from performance deterioration and provide better QoS for users, thus it is the key research content of this thesis.The research status of radio resource management and load balancing technologies is analyzed and summarized in the first place. After that, load balancing algorithms based on application types and user fairness are proposed.In consideration of QoS requirements of different applications and load balance requirement of the heterogeneous system, the thesis presents a load balancing algorithm based on applications types. The algorithm is composed of two parts, one is the joint optimization function which is aimed to guarantee the QoS of users as well as balance the load of the system, and the other is vertical handover process which is designed to minimize the effect of users’mobility and network condition variation on applications and system performance. Simulation results show that the proposed algorithm can provide better performance in call blocking/dropping probability and load balance, compared with least connections load balancing algorithm.Allowing for the long-term coexistence of heterogeneous mobile terminals in the process of communication technology development and network evolution, this thesis proposes a load balancing algorithm based on user fairness. The terminal support index and price index of a RAT (Radio Access Technology) are defined first. Then RAT utility function is presented and RAT selection is based on the utility function, which is aimed to guarantee the fair use of system resources for heterogeneous terminal users. The effects of different proportions of heterogeneous terminals and RAT prices on the call blocking probability are simulated and analyzed. Moreover, the performance of the proposed algorithm is compared with that of random call admission control algorithm. Simulation results show the proposed algorithm can reduce call blocking/dropping probability and improve radio resource utilization.