Handover mechanisms in next generation heterogeneous wireless ...

SECURITY FOR HANDOVER ACROSS HETEROGENEOUS WIRELESS NETWORKS
3.3 Security for Efficient Handover Across Heterogeneous
Networks
The emergence of new access technologies has led to a variety of authentication
solutions. As wireless networks are evolving towards an integrated architecture, the
demand for the standardised security solutions in support of efficient handover across
heterogeneous wireless technologies has increased. Current AAA solutions for wireless
networks are proposed for individual wireless network, but lack a generic approach for
the interworking of heterogeneous wireless networks [51]. Therefore, they need to be
extended to build more general AAA services to facilitate seamless handover when
heterogeneous systems are involved.
3.3.1 Generic AAA Architecture
In a heterogeneous environment with multiple network domains belonging to different
operators, each administrative domain may have an AAA server for managing its own
subscribers. To enable interoperability between those heterogeneous domains, their
network operators need to cooperate with each other as discussed in Sec. 3.1. A more
advanced form of network interoperability - seamless handover, requires that a change
of serving network operator that often results in a new trust relationship to be
established (see Sec. 3.1) can be kept transparent to mobile users. Therefore, a generic
AAA architecture that supports efficient AAA services across heterogeneous networks
of different operators becomes the key to the success of an all-IP-based heterogeneous
wireless infrastructure.
Figure 3.5 shows a Mobile Host (MH) roaming case, in which the MH roams to
disparate networks belonging to different operators. It is assumed that at least one AAA
server resides in each network for providing AAA related services. When the MH hands
over to a foreign network, its authentication process involves the Foreign AAA server
(FAAA) on that network. The MH must be authenticated by the corresponding FAAA
to verify its access privileges established through its Home AAA server (HAAA). The
FAAA may communicate with the MH’s HAAA for authorisation policies. When the
FAAA and the HAAA belong to different operators, a trust relationship between the
two entities must be present for interoperability. This is referred to as an explicit mutual
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