Transport and control issues in multimedia wireless networks

It is not an easy task in the UMTS environment to effectively design the transport and the management of traffic belonging to multimedia teleservices among those defined by ITU Recommendations, due to the hard communication requirements which this kind of application can call for. In this paper the results of an overall research work, dealing with an effective management of multimedia and multi-requirement services in enhanced third-generation mobile radio systems, are presented. The contemporary use of several bearers, one for each traffic component of the service, is proposed as a reference scenario for the transport of multimedia services in future mobile radio environments. The effectiveness of this choice is guaranteed by providing for innovative control techniques, on top of a PRMA-based access protocol, ad-hoc developed to recognise and jointly manage the different parts of a unique multimedia traffic. For this aim, a two-level priority (static and dynamic priorities) mechanism is proposed to be adopted by the higher protocol levels of UMTS for the adptation of call set-up, channel access, handover, and admission control procedures to the nature of multimedia services and for optimising the sharing of radio channel resources and the management of the reservation buffer. Achieved results demonstrate that the priority-based mechanism shows good performance especially during periods in which the system traffic load is high and well reacts to the worsening of multimedia service quality, both in terms of information loss and synchronisation of its different traffic components.