A Survey of IP Layer Mobility Management Protocols in Next Generation Wireless Networks

1. Introduction

The commercial proliferation of multimode wireless terminals (such as laptops, Personal Digital Assistants (PDAs), smart-phones), the explosion of mobile data communications, the emergence of multi-technology environments with disparate capabilities, the integration of such diverse wireless environments and the wide variety of traditional and value-added services offered to end-users have placed extra requirements for mobile communications and computing. On the other hand, traditional voice, fax, email and paging services are increasingly being substituted by real-time multimedia applications, such as video-conferencing, image transfer and audio-streaming. However, the provision of such multimedia services imposes strict Quality of Service (QoS) requirements on the networks. Furthermore, since next-generation wireless networks (NGWNs) must not only provide integrated services, but also capabilities for dynamically relocating mobile terminals (Akyildiz et al., 1999), new challenges have sparked research laboratories to realize an advanced level of tetherless, seamless multimedia services for mobile users roaming between different domains or systems. Given such circumstances, mobility management becomes an important issue to enable telecommunication networks to locate roaming terminals and deliver calls or data to them while these terminals moving into a new service area.

Currently, assorted wireless technologies and networks exist to meet the various needs of mobile users. For example, wireless local area networks (WLANs) enable the delivery of high data-rate services with small radio coverage, cellular networks provide voice and data services with a relatively lower data-rate, yet large coverage, and satellite networks enable global roaming with worldwide coverage at drastic costs. Since these networks are designed for specific service requirements and vary significantly in terms of bandwidth, delay, coverage area, costs and QoS provisioning (Akyildiz et al., 2005), they tend to complement one another, and their integration enables mobile users to be “always best connected” (Gustafsson & Jonsson, 2003) to the most appropriate network.

On other hand, NGWNs introduce a variety of heterogeneities in terms of radio access technologies, network architectures, network protocols and service demands, and such inherent heterogeneities require a common infrastructure to interconnect multiple access systems (Akyildiz et al., 2004). Hence, using all-IP-based infrastructure to support ubiquitous communication appears to be very promising. 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 IP-based technologies to achieve global roaming amongst a variety of access technologies (Akyildiz et al., 2004).

This chapter provides a survey of IP-layer mobility management protocols designed within the working groups of the Internet Engineering Task Force (IETF) for IPv6-based NGWNs. The remainder of the chapter is organized as follows. First, the challenges for mobility management in NGWNs are outlined in order to provide a global view of the research background. Typical IP-layer mobility management protocols such as mobile IPv6, hierarchical mobile IPv6, and fast handovers for mobile IPv6, fast handover for hierarchical mobile IPv6 and proxy mobile IPv6 are described in detail. Future trends in the design of intelligent mobility management protocols are then presented. A conclusion is drawn in the last section.