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Handover mechanisms in next generation heterogeneous wireless ...

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DYNAMIC NEIGHBOUR TRUST INFORMATION RETRIEVAL FOR GLOBAL ROAMING<br />

C mf : the cost of AAA signall<strong>in</strong>g <strong>in</strong>curred between the Mobile Host (MH) and the<br />

Foreign AAA (FAAA);<br />

C nb : the cost of AAA signall<strong>in</strong>g <strong>in</strong>curred between the nPOA FAAA and its<br />

associated AAA broker entry;<br />

C bh : the cost of AAA signall<strong>in</strong>g <strong>in</strong>curred between the Home AAA (HAAA) and its<br />

associated AAA broker entry;<br />

C ob : the cost of AAA signall<strong>in</strong>g <strong>in</strong>curred between the oPOA FAAA and its<br />

associated AAA broker entry;<br />

� : the average cost of signall<strong>in</strong>g <strong>in</strong>curred on each AAA hop across the AAA<br />

broker network;<br />

a m : the cost of the AAA related process<strong>in</strong>g at the MH’s term<strong>in</strong>al;<br />

a h : the cost of the AAA related process<strong>in</strong>g at the HAAA;<br />

Accord<strong>in</strong>g to the re-authentication procedure of Figure 4.2, the handover part signall<strong>in</strong>g<br />

cost C H of the NTC retrieval can be represented as:<br />

<strong>in</strong> which<br />

C H � 5 � C mf � 4 � C nb � 4 � Cbh<br />

� a m � 2 � ah<br />

� 4�<br />

� h (Equation 4.2)<br />

nb<br />

hnb �i� represents the trust association hops that the AAA message orig<strong>in</strong>ated<br />

from the nPOA traverses on the AAA broker network <strong>in</strong> handover. It is assumes that the<br />

signall<strong>in</strong>g overheads for the AAA message’s transmission between the nPOA FAAA<br />

and its associated broker, and its transmission between the HAAA and its associated<br />

broker, are the same as what is required for transmitt<strong>in</strong>g AAA message between two<br />

AAA brokers. Thus, when C C � � , the handover part signall<strong>in</strong>g cost C H can be<br />

simplified as:<br />

H<br />

mf<br />

fb<br />

� bh<br />

�2�hnb �i���amah C � 5 � C � 4�<br />

�<br />

� 2<br />

(Equation 4.3)<br />

- 65 -<br />

�i�

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