A Project on Combining Laboratory and Simulation Experiments on Voice Over IP

The emphasis of the Telecommunications Engineering Technology program at Texas A&M has been changing from traditional telephony to internet-protocol (IP) based networks. Following this trend, our goal is to create new learning materials and teaching strategies that would improve undergraduate education and prepare our students to industry practice. For instance, a traditional telephony testing class was changed to teach networking modeling and simulation using Opnet network simulator. With this new tool, instructors were able to cover different protocols of local and wide area networks. In addition, students were better exposed to the concept of statistical multiplexing, queuing theory, and performance metrics. One drawback, however, was that the students would in some cases prefer hands-on laboratory experiments, or more tangible experiments. From an instructor’s perspective, we also observed that the students would set parameters in the network simulator without fully understanding their effects. In summary, there was a need to complement the simulation experiments, as a way to help students validate their simulations results. Thus, in Fall 2008 the students were assigned to a simulation/laboratory project on Voice over IP (VoIP) bandwidth calculation. This project has the goal of teaching the different bandwidth requirements of VoIP audio encoders/decoders (codecs). They simulate a local area network with VoIP phones as end devices. In parallel, lecture time is spent in the laboratory in which we have real VoIP phones and a soft-switch. In this paper we share the details of this project and show that this has been a positive experience with the students, where they learn to analyze simulation results and compare the trade-offs of simulation models vs. real world systems.