Research On Prediction Model Based Handoff Technologies For Virtual Terminal System In Wireless Ubiquitous Environment

In wireless ubiquitous environment, multiple wireless technologies coexist and terminals arevaried. Meanwhile, a single device has been unable to meet users’ demand of high Quality ofService (QoS). In this case, virtual terminal system based on cooperation of terminals emerges asthe times require. Characteristics and capabilities of multiple terminals are fused, thereby providinghigh Quality of Experience (QoE) for users. On the basis of this, the handoff technology as one ofkey of virtual terminal system is researched in this thesis. Based on collaborative handofftechnology, two scenarios i.e. a user with multiple terminals and multiple users each with a terminalare mainly discussed. The major works are as follows:Firstly, the basic concept, characteristics, key technologies and main applications of virtualterminal system are introduced. Then main characteristics of vertical handoff and its typical scenesare briefly introduced.Secondly, the related concepts of vertical handoff technology are introduced in wirelessubiquitous environment. Then, various vertical handoff technologies based on decision criterion aresummarized and compared.Thirdly, the theoretical analysis of the handoff trigger time selection is introduced. Then, analgorithm is proposed to predict the optimal handoff trigger time through the estimation of handoffdelay and the prediction of received signal strength (RSS). Simulation results show that thisalgorithm can effectively reduce the probability of handoff failure and the packet loss ratio.Finally, regarding to the vertical handoff among multiple users, a terminal prediction algorithmis proposed through the construction of revenue function and the prediction of network parameters.Simulation results show that this algorithm can make users obtain more revenue and effectivelyreduce the packet loss ratio.