Evaluating the Quality of Service of a Floor-Controlled Centralized Conference System for Distance Learning

This paper describes a floor-controlled centralized conference system being developed for LARC (Laboratory of Computer Architecture and Network - Escola Politecnica - Engineering School) distance learning tool Floor control was used to regulate interaction and access to the audio channel and to restrict network bandwidth usage. A floor control protocol and a light session protocol were developed. Implementation was made using web technology in order to ease integration with web-based systems. This system runs over IP unicast communication infrastructure. Some experiments were made in order to evaluate the quality of service of a centralized conference system for distance learning. The quality of service parameters evaluated for the conference system user were usability, interactivity, voice subjective quality and bandwidth needed, while the parameters evaluated for the conference system owner were bandwidth, processing costs and system scalability. This paper aims to present the results of such experiments. In the first one, floor control was tested as a mechanism for restricting bandwidth consumption in centralized conferences and the bandwidth needed by the user, by the multipoint control unit (MCU) and by the conference system owner were evaluated. In the second one, delay and packet loss were seen through the use of a real world scenario (remote tests), impacting the voice subjective quality and the interactivity among conference participants. In the last one, a subjective experience reveals information about the usability of the system. These results have taken as basis to improve the current conference system and the modus operandi of the distance learning system as a whole.