Modeling And Performance Evaluation Of Packet Voice Streams

The broadband networks based on ATM cell transmission are expected to carry a variety of traffic types in integrated fashion. This differs considerably from the case of the century-old, ubiquitous, circuit-switched telephone networks designed primarily to handle voice, and the much more recent packet-switched networks designed to handle data. In order to discuss the transmission of packet voice signals over ATM networks, and design networks which meet the strict delay constraints required for acceptable voice reconstruction, models which accurately reflect the statistical properties of packet voice systems are needed.In a packet voice communication system, packets are fed to a common queue by a number of independent voice sources and are removed from this queue on a first-come-first-serve basis for transmission over a communication link of finite capacity. Each voice source alternates between active periods, during which packets are generated at regular intervals, and inactive periods, during which no packets are generated. So a number of voice traffic streams are multiplexed and buffered at a user-network interface (UNI) port for transmission through an ATM network.In this paper, we discuss two models, a Markov-modulated Poisson process, and a fluid flow model. In order to analyse the fluid flow model, the eigenvalue method is used; MMPP model is discussed with the help of the matrix geometric solution technique. Both methods are given in detail. The programs are written and run to assess the statistical behavior of such systems. Parameters of the model are the average duration of active and inactive periods, the packet generation rate, the communication link capacity, and the total number of voice sources. Conclusions are drawn regarding the effects of parameter changes on system performance. The fluid flow model is alsoused for admission and access control.