| Summary: | 碩士 === 國立清華大學 === 資訊科學學系 === 83 === Several multimedia applications, such as video conference,
video on demand, and distance learning, require the network to
provide multicast service so that the multimedia traffic could
be serviced more efficiently. The most effective way to
provide the multicast service is based on a multicast tree.
Recently, the ATM networks are matured to be the high speed
backbone network. Moreover, the ATM networks also provide
multicast functions. By the growing progress and facility of
communication, it makes the PCN widespread. The difference
between PCN and other network is the movement of the mobile
terminal in the PCN. The path will take longer, when the mobile
terminal migrates to different base station. However, the
appropriate path migration is able to decrease the waste of
resources in the network. The PCN based on the ATM can build up
the multicast tree by the features of multicast. The distance
increasing and the resources exhausted come after the movement
of the mobile terminal. It is the best choice to reduce the
resources of the multicast tree and the used links. Therefore,
it is necessary to migrate the multicast tree when the mobile
terminals change the location. In this thesis, a distributed
multicast tree migration scheme for ATM based PCN is proposed.
Based on this scheme, a multicast tree can be adjusted
dynamically when the mobile terminals move around so that the
resources consumed by the multicast tree are well controlled.
Simulation results show that the tree migration scheme performs
used less than the scheme without tree migration in terms of
blocking rate, the number of constructed multicast trees, the
average diameter of the constructed multicast tree (maximum
delay), and the bandwidth utilization.
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