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Handover mechanisms in next generation heterogeneous wireless ...

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TRUST ASSISTED HANDOVER ALGORITHM FOR RELIABLE HANDOVER<br />

Figure 5.7 Load balance factor vs. Trust density [ p � 50%<br />

]<br />

It has been observed that the level of trust association between home network and<br />

foreign networks can have certa<strong>in</strong> effect on handover delay if the MHOA is applied.<br />

Figure 5.9 shows that the handover delay grows from 1070ms to 1255ms, when the<br />

probability of no trust association (trust density equals 0.3) drops from 1 to 0 <strong>in</strong> the<br />

MHOA applied case. The results suggest that reduc<strong>in</strong>g the trust ambiguity <strong>in</strong> the AAA<br />

relationship between networks may improve handover performance <strong>in</strong> low trust density<br />

scenarios. In comparison, the same experiment was conducted us<strong>in</strong>g the THOA. Figure<br />

5.8 shows the experimental results of apply<strong>in</strong>g the THOA. The THOA apparently<br />

mitigates the side effect of implement<strong>in</strong>g the f<strong>in</strong>e-gra<strong>in</strong>ed AAA policies (e.g. a detailed<br />

classification of subscribers for authorisation) <strong>in</strong> home networks.<br />

- 103 -<br />

A

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