Handover mechanisms in next generation heterogeneous wireless ...

DYNAMIC NEIGHBOUR TRUST INFORMATION RETRIEVAL FOR GLOBAL ROAMING
AAA services are considered. It is assumed that AAA services intermediated by too
many third parties may be less reliable. An applicable approach of modelling the NTC
is to have the NTC correlated to the number of Trust Association Hops (TAH) on the
AAA path between two networks. For example, the AAA path from the visited network
to the MH’s home network covers two TAHs as illustrated in Figure 4.3. The TAH
count would be the right parameter to show how a network is trust- associated with
another.
Figure 4.3 A network trust correlation model
Therefore, the NTC between any pair of networks can be quantified as:
NTC � h(i)
(Equation 4.1)
where h means the number of trust association hops and i represents the distance
between two networks.
4.3 Trust Information Retrieval and Distribution
Using the trust association hop based NTC model, the NTC between two networks can
be promptly quantified when the authentication messages are exchanged. Because
authentication is required in every handover attempt, the proposed scheme makes use of
handover authentication process to obtain the NTC data between a pair of networks.
Basically, the NTC data retrieval can be performed every time a mobile user attaches to
a visited network in a handover. Because the authentication request passes through the
visited network, e.g. the oPOA as shown in Figure 4.4, and would be processed at the
HAAA, both the visited network and the HAAA have the knowledge of their NTC data.
The NTC data retrieval is conducted during the handover. The distribution of a
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