Analysis of a generic model for a bottleneck link in an integrated services communications network

We develop and analyse a generic model for performance evaluation, parameter optimisation and dimensioning of a bottleneck link in an integrated services communications network. Possible application areas include ip, atm and gsm/gprs networks. The model enables analytical evaluation for a scenario of integrated speech, video and data services, selected for the fundamental differences in their service characteristics. While a speech call is assigned a single resource unit for its entire duration, both video and data calls can handle varying resource assignments. The principal distinction between these elastic call types, is that in case of video calls, a more generous resource assignment implies a better throughput and thus video quality, while for data calls the increased throughput implies a reduced transfer time. Markov chain analysis is applied to derive basic performance measures such as the expected resource utilization, service-specific blocking probabilities and the expected video and data qos. Furthermore, analytical expressions are derived for the expected video and data qos, conditional on the call duration or file size, respectively, and on the system state on arrival. As a potential application, these measures can be fed back to the caller as an indication of the expected qos. A numerical study, focussing on a wireless access network, is included to demonstrate the merit of the presented generic model and performance analysis.