Juan C. Granda

Ph.D. Computer Science

Associate Professor of Computer Architecture and Technology

University of Oviedo, Spain

Juan C. Granda, "Characterization, assessment and optimization of interactive multimedia systems in the scope of synchronous e-learning", University of Oviedo (Spain), 2008. (2008-07-28)
Supervised by: F.J. Suárez and D.F. García.
Abstract:
Interactive multimedia systems have grown in popularity as throughput of personal computers improves. Computer-assisted learning or e-learning is a field in which these systems are used successfully. If these systems impose temporal restrictions on the learning process they are called synchronous e-learning systems, otherwise they are called asynchronous e-learning systems. The former implies the use of multimedia technologies to enable real-time interaction between instructor and students.
Traditionally, tools such as videoconference or computer-supported collaborative tools are used in order to carry out synchronous e-learning activities. However, these tools are not designed with the aim of e-learning. In some cases, rather than a single tool, multiple tools are used during these activities, each of them providing a specific functionality. Even though some tools are designed with the aim of providing support to e-learning activities, they usually constitute complex platforms with many dedicated servers. This PhD thesis identifies the characteristics to be accomplished by a tool in order to provide support to the development of synchronous e-learning activities. Thus, an extensive survey of the tools used to promote synchronous e-learning session is carried out, which covers market tools and others developed in the investigation environment. All of them offer similar functionalities, so this PhD thesis analyzes the set of common functionality that every tool must satisfy to be appropriate for synchronous e-learning.
Moreover, large business corporations have discovered the importance of synchronous e-learning applied to the continuous training of human resources. Synchronous e-learning is now another option to promote training. In this PhD thesis a synchronous e-learning prototype platform is developed to provide support to e-training activities in the scope of a large international company. All possible designs following the requirements extracted from the previous characterization of synchronous e-learning tools are discussed.
The final design is proposed with special emphasis on the definition of the interaction model allowed between instructor and student. It must resolve which multimedia data will flow in a one-way fashion from the instructor to the students, and which data will flow in a bidirectional way to enable collaborative work. This fact has enormous consequences in the way data is delivered and the restrictions that the global platform imposes on the underlying network. Specifically, the prototype platform will use multicast delivery whenever possible, for example in the company network. If multicast delivery is not available, a relay server developed within this PhD thesis could be used to emulate the behavior of a multicast network. With this server, highly-scalable multi-server architectures are possible. All multimedia data is organized in multiple RTP sessions according to its media type, and conveyed using multicast delivery whether or not they are continuous media (audio or video). The advantages of using RTP with non-continuous media are listed and how the prototype platform takes advantage of them.
The final prototype is the result of an iterative process of continuous design and implementation to estimate the behavior of the platform depending on the design decisions. Based on these evaluations, multiple optimizations are proposed, which aim to improve the global performance of the prototype. These optimizations can be applied to any synchronous e-learning tool.
Furthermore, the resulting prototype platform must be simple to use. This is a consequence of two factors. Firstly, the users of the prototype platform will be employees with little knowledge of computing. Secondly, the maintenance of the whole prototype platform should be minimum, so specialized staff is not needed to manage it.
Sometimes, it is necessary to assume a deliberate functionality reduction in order to satisfy network bandwidth requirements, especially when little bandwidth is available. Therefore, the prototype platform offers the minimal functionality to promote synchronous e-learning activities in the scope of training in large enterprises, using as few resources as possible. Thus, the prototype could operate in any network scenario.
Finally, in this PhD thesis the results of the use of the prototype in real synchronous e-learning situations are documented and discussed. Questionnaires are used to estimate the satisfaction of participants attending e-learning sessions.