Comparing the QoS of Internet audio mechanisms via formal methods
ACM Transactions on Modeling and Computer Simulation (TOMACS)
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We compute and compare the quality of service (QoS) of two soft real time applications concerning audio transmission over the Internet. The considered metric is the user perception of audio, which is represented by the average packet audio playout delay vs. the packet loss rate. The study is conducted on formal descriptions of the two audio mechanisms expressed in the algebraic language EMPA which are analyzed through the software tool TwoTowers under various (experimentally obtained on the field or randomly generated) traffic conditions. A stochastically timed process algebra like EMPA has been used because of its compositional support to system modeling, its capability of allowing functional properties of systems to be formally verified (unlike conventional simulators), and its adequacy to represent generally distributed durations (which come into play in the two audio mechanisms) when extended with value passing features. The comparison reveals that neither of the two mechanisms outperforms the other one in general, as their performance depends on the traffic conditions.