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|Title:||Media independent handover platform with context-awareness extension in heterogeneous wireless networks|
|Keywords:||Wireless communication systems -- Equipment and supplies -- Design and construction.|
Cell phone systems.
Hong Kong Polytechnic University -- Dissertations
|Publisher:||The Hong Kong Polytechnic University|
|Abstract:||In the past decade, we have witnessed the advance of technologies in wireless communication and mobile computing. Wireless access technologies including Wi-Fi, 3G, and Worldwide Interoperability for Microwave Access (WiMAX) enable mobile users to get wide access to the Internet. However, due to the limited coverage of wireless networks, the merits and shortcomings of different wireless technologies, mobile terminals are often equipped with more than one type of wireless access interfaces. Such a terminal is called multi-mode terminal. Multi-mode terminals and heterogeneous wireless networks pose new challenges to seamless communication, in particular, the handover management. The IEEE 802.21 is a standard that defines the Media Independent Handover (MIH) framework to support handover management in a heterogeneous wireless network environment. MIH consists of three services: MIH Event Service (MES), MIH Information Service (MIS), and MIH Command Service (MCS), which together serve to facilitate smart handover, providing functions for handover discovery, handover trigger and handover decision. Most existing works on MIH make use of MIH as a tool to provide support to high level protocols such as Mobile IP (MIP), Session Initiation Protocol (SIP) or to assist handover management in the aspect of handover trigger or handover discovery. Some works introduce new parameters into the MIH functions to improve MIH services by providing additional information, such as the neighbour map. Since MIH framework provides services for mobile users, therefore, the quality of MIH services is finally evaluated by its users. In the wireless mobile environment, different mobile users have different mobility patterns, suffering different environmental interference, and have various requirements on the cost, efficiency or accuracy. This kind of difference is distinct according to different users. User context represents the differences in the wireless mobile environment. However, unified MIH services are not aware of different user context, and thus cannot provide specified services to improve user experience. To address this shortcoming, we extend the MIH platform with context-awareness (MIHCA), and design context-aware applications for MIH services to show the improvement of service quality.|
In the first part of this thesis, we present our MIH platform with context-awareness extension. Because the MIH framework involves several technology interfaces, having a large number of functions, and modifications are required both on the mobile terminals and remote networks. It is hard to carry out all the standard MIH functions in the short study time. So we name our MIH platform with basic functions as customized media independent handover framework (CMIH). We represent the work flow, service figures for CMIH services, and describe the context provider, context processor, and context-aware entity for the context-awareness module. In the second part of this thesis, we provide a context-aware prediction for the "MIH link going down" event. It is a handover trigger in handover management. The "MIH link going down" event is defined in the MES. Unlike existing works, which focus on signal strength threshold, our proposed mechanism can guarantee user required handover preparation time. A timely handover trigger can be generated according to our test results. In the third part of this thesis, we present a clustering based context-aware mechanism for predicting stability of wireless links in our framework. This context-aware prediction belongs to the MIS. Due to the limited coverage of a wireless network, wireless interference, and user mobility, wireless links break down frequently. It causes service interruption, network overhead and latency. Therefore, a stable link is preferred by mobile users, and a criterion that can judge the link is needed. Unlike existing works, which require prior knowledge on network environment and user mobility pattern, our proposed mechanism can automatically be aware of environmental interference, user location, user handover policy, and user mobility. A K-mean clustering method is adopted to process the classification of user context, and then the link stability is predicted with conditional probability according to different classifications. Experimental results show that our proposed context-aware prediction on link stability can well guide the mobile user to obtain a stable wireless link.
|Description:||xiv, 75 p. : ill. ; 30 cm.|
PolyU Library Call No.: [THS] LG51 .H577M COMP 2013 Xiong
|Rights:||All rights reserved.|
|Appears in Collections:||Thesis|
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Checked on Aug 20, 2017
Checked on Aug 20, 2017
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