Research On Vertical Handoff Algorithm And Decision Mechanism

The future communication network is an integrated network with different access technologies overlapped. The ultimate goal of the integration is to provide users with"Always Best Connected"(ABC) access service. Mobility management of heterogeneous wireless networks is the technical support and guarantee for ABC service. As an important part of the mobility management, the vertical handoff technology that ensures the continuity of the session when vertical handoff occurs has become one of the most challenging key technologies in heterogeneous network。How to design efficient handoff algorithm and effective handoff mechanism is still a remaining issue. According to the limitations in the existing researches of vertical handoff, in this paper, we divide the vertical handoff problem into two issues: network selection and comprehensive handoff assessment. For the first issue, we propose a Service-aware based GR-AH network selection algorithm, and for the second one, we propose a comprehensive vertical handoff assessment system.The Service-aware based GR-AH network selection algorithm solves the network properties related to QOS , such as RSS, packet loss rate, etc, separately, to avoid the negative influence of the QoS irrelative network properties on the network selection result. The simulation results show that the proposed Service-aware based GR-AH network selection algorithm can select the most suitable network for the current application type objectively and effectively, furthermore, it has a better performance on vertical handoff numbers compared to the SAW algorithm.Finally, we provide a detailed discussion about the design ideas, system framework, the modules and their operating procedures, system operating procedures of the proposed Extendable Comprehensive Vertical Handoff Assessment System (ECVHAS). The Extendable Comprehensive Vertical Handoff Assessment System integrated the Service-aware based GR-AH network selection algorithm module, network acceptance capacity module and motion estimation module as one of its system modules. Besides, we can add good and new researches as modules to the Extendable Comprehensive Vertical Handoff Assessment System for improving vertical handoff performance in the future. The separate and modular solving idea of the Extendable Comprehensive Vertical Handoff Assessment system can well adapt to the future development of mobile communications.