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Top1. Introduction
Today, we witness the commercial proliferation of multimode wireless terminals, i.e. smart-phone, iPad, iPod, and the explosion of mobile data. To meet end-users’ needs, multi-technology environments with disparate capabilities are emerging and integrated together. All these changes in wireless communications world have placed extra requirements for mobile operators. Traditional voice, fax, email and paging services need to be replaced by real-time multimedia applications, i.e. audio & video streaming, image transfer. However, the provision of such multimedia services imposes new quality of service (QoS) requirements on the networks. It is well-known that next-generation wireless networks must provide integrated services with more capabilities to dynamically relocate mobile terminals (Akyildiz et al., 1999). Therefore new challenges have sparked researcher to find new solutions, which can offer undisrupted/seamless multimedia services to roaming users. Given such circumstances, mobility management becomes an important issue to enable telecommunication networks to locate roaming terminals and deliver calls/data to them while these terminals moving into a new access network/domain.
Currently, various wireless technologies and networks exist to satisfy mobile users’ requirements. For example, wireless local area networks make it possible to deliver high data-rate services within small radio coverage area; cellular networks provide voice and data services with a relatively lower data-rate, yet large coverage; satellite networks enable global roaming with worldwide coverage at drastic costs. These networks/systems are designed for meet specific service needs, thus they are significantly different in terms of bandwidth, delay, coverage area, costs and QoS provisioning (Akyildiz et al., 2005). As a result, they tend to complement one another to empower mobile users with “always best connected” (Gustafsson & Jonsson, 2003) to the most appropriate network.
Meanwhile, a variety of heterogeneities exist within next-generation wireless networks (NGWNs), i.e. radio access technology, network architecture, network protocol and service demands. Such inherent heterogeneities require a common infrastructure to interconnect multiple access systems (Akyildiz et al., 2004). Under this circumstance, using all-IP-based infrastructure to support ubiquitous communication appears to be very promising and acceptable by the telecom industry (Saha et al., 2004). First of all, IP-based wireless networks are better suited to support the rapidly growing mobile data and multimedia applications (Chen & Zhang, 2004). This is confirmed by the fact that IPv6 (Deering & Hinden, 1998) is designated as the only IP version supported for IP Multimedia Subsystem (IMS) within the Third Generation Partnership Project (3GPP) (Arkko et al., 2003). Secondly, IP-based wireless networks have already brought global success to Internet services and they will also prove to be a successful platform to foster future mobile services (Chen & Zhang, 2004). Last but not least, IP-based wireless networks are independent of the underlying radio access technologies, making it possible and feasible to maintain seamless connectivity over different radio technologies, while offering global roaming capabilities (Chen & Zhang, 2004). Therefore, NGWNs are designed to take advantage of all-IP-based infrastructure to achieve global roaming amongst a variety of radio access technologies (Akyildiz et al., 2004). The contributions of this paper are two-fold, summarized as follow:
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We present an overview of host-based mobility protocols for next-generation wireless networks: mobile IPv6 (MIPv6) and its enhancements, i.e. fast handovers for MIPv6 (FMIPv6), hierarchical MIPv6 (HMIPv6) and fast handoff for HMIPv6 (F-HMIPv6).
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We evaluate the handoff performance for MIPv6 and its enhancements through analytical modeling, and study carefully the effect of various network parameters on the performance.