Research On Multi-Access And Handover Mechanism In Heterogeneous Networks

In the future, mobile communication system will be secure and QoS guaranteed all-IP heterogeneous integrated networks which are coexisted, cooperative and supportable for the mobility of terminal. In order to realize the intergration of heterogeneous networks, the access selection and handover technologies between different networks become important issues.Based on existing methods of calculating weights, this paper proposes a new combined weights method based on the overall difference and cooperative game, and utilize this method to fulfill distributed access selection. Simulations are conducted with different parameters and scenarios to verify the feasibility and superiority of the distributed access selection based on combined weights.A new parameter named the network weight is proposed and the problem of centralized access selection is modelled as an integer linear programming problem. Two suboptimal solution algorithms are improved, that are E-ABR algorithm and the E-RBR algorithm, which greatly reduce the computational complexity of the optimal algorithm. This dissertation sets up different scenarios and corresponding parameters so as to simulate the performance of the two algorithms and verify both the feasibility and the superiority.Finally, the disadvantages of MIP/HNMM during vertical handover are analyzed in this thesis by researching switch process and signaling interaction, and then improved buffer-and-forward policy and multicast policy are proposed. With network simulation tool, the paper proves that the suggested strategies can effectively improve the system performance.