Handover mechanisms in next generation heterogeneous wireless ...

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INTRODUCTION economic and practical solution. Seamless integrating heterogeneous wireless networks would enable a ubiquitous high speed access infrastructure for mobile users. For a mobile user in heterogeneous wireless networks, ubiquitous access can be further identified as having capabilities in two aspects: service continuity and service quality. For service continuity, a mobile user is often engaged in a so-called handover operation to ensure that its user session is maintained continuously without being aware of the underlaying operation. In a Global System for Mobile communications (GSM) network, for example, a mobile user is connected to a Base Station (BS) via a radio link. If the mobile user moves to the coverage area of another BS, the radio link to the old BS would be eventually disconnected, and a radio link to a new BS should be established to continue the telephony conversation. Handover is referred to as the process of switching user connections in order to keep ongoing connections uninterrupted. On an integrated network infrastructure, a mobile user switches between heterogeneous wireless networks to obtain the best available connection to the network. A typical case of a handover for service continuity in heterogeneous wireless networks is the handover of a mobile user’s radio link from a high speed data link e.g. IEEE 802.11 to a low rate data link e.g. UMTS when it moves out of a Wi-Fi hotspot. Apart from handover for service continuity, handover can be initiated for optimising service quality. Unlike a mobile user of a GSM network who makes solely voice calls, a mobile user of UMTS or WLAN may have multiple data services such as voice, video, and messaging being carried on top of the Internet Protocol (IP) at the same time. In this case, different priorities need to be applied to these services so as to guarantee a certain level of performance to a specific data flow, especially when the network capacity is limited. Therefore, service continuity and service quality would be essential to mobile users in the Next Generation Heterogeneous Wireless Networks. When multiple wireless networks provide overlapped radio coverage to a mobile user, handover can be an effective method of optimising service quality. This is achieved by avoiding those wireless networks with less satisfactory conditions. For example, a mobile user being served by a UMTS network may choose to switch to an available Wi-Fi hotspot to obtain higher bandwidth for its bandwidth-hunger applications once the Wi-Fi service - 2 -
INTRODUCTION becomes available. Handover between networks of the same type occurs for balancing network load or other reasons. Maintaining a mobile user’s service continuity and service quality in a handover makes sure that the handover is performed seamlessly. Seamless handover makes the transfer of a mobile user’s network connections transparent (without perceptible interruption of services) to upper layer applications. With seamless handover, a mobile user can obtain service portability and application persistence across heterogeneous wireless networks. Generally, seamless handover will be a key enabling technique for the Next Generation Heterogeneous Wireless Networks. 1.1 Motivation In the Next Generation Wireless Networks, various types of wireless networks including UMTS and WLAN are expected to be interconnected to support ubiquitous high speed data services. These wireless systems were designed independently and targeting different service types, data rates, and users, and thus require an intelligent interworking approach to be effective. In heterogeneous wireless networks, both the mobile user and the interconnected wireless networks play an important role in determining how service continuity and service quality can be served in a handover. Providing service continuity and service quality in a heterogeneous network environment would create several research challenges in the Next Generation Heterogeneous Wireless Networks and these challenges are itemised below: � Access technologies: Heterogeneous wireless networks that employ a number of radio technologies may have overlapped radio coverage. A mobile user needs to switch between access networks to maintain service continuity and optimise service quality. How does a mobile user deal with heterogeneous access technologies? � Network architectures: Heterogeneous wireless networks rely on different network architectures and protocols for transport, routing, mobility management and so forth. How will they be interconnected in an integral manner to facilitate the cooperation between themselves? � Network conditions: Network conditions such as bandwidth, delay, jitter and so forth may vary across wireless networks, and result in different service quality to - 3 -
Page 1 and 2: Handover Mechanisms in Next Generat
Page 3 and 4: ACKNOWLEDGMENT First of all, I woul
Page 5 and 6: TABLE OF CONTENTS 4.4.2 Power Save
Page 7 and 8: LIST OF FIGURES LIST OF FIGURES Fig
Page 9 and 10: LIST OF FIGURES Figure 7.2 A generi
Page 11 and 12: ABSTRACT New access technologies su
Page 13: Chapter 1 INTRODUCTION New access t
Page 17 and 18: INTRODUCTION The above multipliciti
Page 19 and 20: INTRODUCTION network trust pattern
Page 21 and 22: INTRODUCTION 1.3 Related Publicatio
Page 23 and 24: INTRODUCTION TECHNICAL REPORTS XIII
Page 25 and 26: HANDOVER MANAGEMENT horizontally. H
Page 27 and 28: HANDOVER MANAGEMENT The objective o
Page 29 and 30: HANDOVER MANAGEMENT air interface,
Page 31 and 32: HANDOVER MANAGEMENT proposed archit
Page 33 and 34: HANDOVER MANAGEMENT Access point (A
Page 35 and 36: HANDOVER MANAGEMENT users. Moreover
Page 37 and 38: HANDOVER MANAGEMENT For IEEE 802.11
Page 39 and 40: HANDOVER MANAGEMENT The two schemes
Page 41 and 42: HANDOVER MANAGEMENT When a MH is mo
Page 43 and 44: 3.1 Introduction Chapter 3 HANDOVER
Page 45 and 46: SECURITY FOR HANDOVER ACROSS HETERO
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SECURITY FOR HANDOVER ACROSS HETERO
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SECURITY FOR HANDOVER ACROSS HETERO
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DYNAMIC NEIGHBOUR TRUST INFORMATION
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Chapter 5 TRUST ASSISTED HANDOVER A
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TRUST ASSISTED HANDOVER ALGORITHM F
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Chapter 6 PROXY BASED AUTHENTICATIO
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PROXY BASED AUTHENTICATION LOCALISA
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MULTI-INTERFACE MOBILE MODEL FOR ME
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CONCLUSIONS AND FUTURE RESEARCH WOR
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ABBREVIATIONS 3G 3rd Generation Wir
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ABBREVIATIONS LS Location Server MH
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ABBREVIATIONS THOA Trust Assisted H
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REFERENCES [12] C. Politis, T. Oda,
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REFERENCES [37] Wi-Fi Alliance, "Wi
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REFERENCES presented at IEEE Intern
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REFERENCES [90] R. Verdone and A. Z
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REFERENCES [116] K. E. Malki and H.
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