In a mobile communication system network performance varies considerably when handovers occur. This occurrence strongly impacts the design of the buffer compensation based techniques usually used in the fixed communication environments for minimizing probability of asynchronism between the different media composing a multimedia session. This paper provides an analytical paradigm for dimensioning synchronization buffers at the interface node between the wired and the wireless networks when network delay varies during a multimedia session due to the user mobility. For this purpose, the factors related to terminal mobility which have to be taken into account in the design of a synchronization mechanism are briefly introduced and appropriate user-perceived Quality of Service parameters referring to the synchronization of multimedia services are also introduced.

The IETF Mobile IPv6 protocol has been developped to manage global (macro) mobility. It is not adapted to local (micro) mobility since it does not support any kind of hierarchy. This paper presents a hierarchical protocol, built on top of Mobile IPv6, that separates local mobility (within a site) from global mobility (across sites) management. Local handoffs are managed locally and transparently to a mobile node'correspondent hosts while global mobility is managed with Mobile IPv6. Our scheme is flexible (several levels of hierarchy can be used), scalable, interworks with Mobile IPv6 and can be deployed gradually.