One noticeable trend for next generation mobile communication systems is the shift from the traditional vertically integrated approach in system design towards architectures that enable access to a set of common IP services through a variety of heterogeneous access technologies. With the introduction of multimode mobile devices, the next step in the integration of heterogeneous mobile networks, i.e. inter-access service continuity, gains relevance. This chapter reviews emerging heterogeneous access networks and their integration, and studies service continuity, including the relevance of Mobile IPv4 and Mobile IPv6 and other mobility solutions at, above, and below IP layer, in this context. We propose a new system architecture, which combines Mobile IP and IPsec to introduce multi-access mobility in a 3GPP operator environment. As part of the proposed framework we present new techniques for mobility security association bootstrapping and for enhancing the mobile device's NAPT traversal implementation. The selected architecture is evaluated using an experimental laboratory setup. The results are used to build up an analysis of the solution and draw up some conclusions on the viability of the selected architecture and associated performance.

Introduction

Mobile devices are exposed to an increasing selection of wireless access technologies ranging from wide range macro cellular technologies to short range local access technologies.