Research And Simulation Of Vertical Handoff Decision Algorithms For Heterogeneous Wireless Networks

Nowadays, with rapid development of wireless mobile communication technology, the network which integrates various heterogeneous ratio access technologies is going to appear. The integration of networks meets user's requirements of high Quality of Service (QoS), but also brings difficulties to radio resource management. As a part of radio resource management, handoff management is particularly important as inappropriate handoff strategy will lead to handoff's failure and affects the performance of the entire heterogeneous networks. In order to guarantee seamless handoff, it is required to design reasonable vertical handoff decision algorithms for heterogeneous wireless networks.Two handoff decision algorithms based on stability period's adjustment, Dynamic Stability Period Decision (DSPD) algorithm and Fuzzy Data-based Stability Period Decision (FDSPD) algorithm, are designed after the analysis of vertical handoff decision. The two algorithms, both based on setting stability period before performing handoff:DSPD algorithm calculates the stability period using a new formula and makes it adjusted dynamically relying on the utility ratios of the target network to the current one with the changes of networks' condition; FDSPD algorithm adopts fuzzy data-based method. After obtaining more status parameters of the networks and users, it uses different combinations of status parameters corresponding to different time value to determine the stability period and then triggers handoff in an appropriate time. After that, they are applied to solve the handoff queuing problem in order to reduce impact to the network performance due to handoff synchronization to the largest extent.In order to evaluate the performance, the proposed algorithms are simulated in an environment of the heterogeneous wireless networks. Compared with the existing algorithms, the proposed schemes, which adjust the stability period more easily and reasonably, can improve the handoff call success rate and reduce unnecessary handoffs effectively.