Systems Optimization for Mobility Management

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【作者】 Ashutosh Dutta 

【摘要】Systems Optimization for Mobility Management Ashutosh Dutta Wireless network mobility frees the user from location dependence but requires additional mechanism to preserve network connectivity. Mobility events occur when user movement causes one network connection to be replaced by another. A network connection has associated with it properties; for example; network attachment points; network identifiers; and security associations. The mechanisms supporting mobility events rebind these properties; often requiring operations at multiple layers of the protocol stack. The rebinding is a sequential process and each process takes a finite amount of time. This overall process generates a period of time in which network service is degraded by transient data loss and increased end-to-end delay. Application specific and protocol specific ad hoc solutions are available for mitigating the service disruption. However; formal techniques to characterize this problem and to develop optimization methodologies for these processes have not been studied. This dissertation develops a systematic and formalized systems model that analyzes the basic operations associated with a mobility event; studies the behavioral properties of the system and characterizes several systems optimization techniques for these processes. The proposed formal mobility systems model represents these basic operations in the form of a discrete event dynamic system. I analyze this general mobility systems framework and develop several methodologies that can model systems optimization techniques. In particular; I develop methodologies to model the optimization for many of the basic operations; such as discovery; configuration; binding update; and media redirection. Then; I apply these methodologies to prototype mobility systems that can support subnet; domain and inter-technology roaming for real-time and streaming applications in the wireless Internet. Some of these methodologies include proactive network and resource discovery; pre-authentication; pre-configuration; reduction of binding delay; and minimizing the effect of media redirection delay by means of dynamic buffering and multicasting. I validate the mobility systems model by using it to analytically assess related mobility protocols for both interactive and multicast streaming traffic. The model can result in an analytical assessment of the techniques that can be directly compared to my experimental results under certain resource constraint and various networking parameters; such as mobility rate; packet-to-mobility ratio; simultaneous mobility; distance between the communicating nodes; and network access characteristics. I perform a comparative analysis of our optimized mobility management schemes with similar network layer mobility protocols and other fast-handoff mechanisms.