Abstract:

Bandwidth limitation troubles caused by the digital-divide are bound to curtail remote activities. This problem has been deeply investigated but, also due to the ever increasing bandwidth demand of advanced applications, is far from being solved.
In this work, the digital-divide is discussed from an e/m-Learning perspective and, more generally, in context of remote groupworking. Students who get connected from areas affected by such problem, in fact, can not fully benefit from one of the most important features of e/m-Learning services, i.e. the independence of end-users in time and space. In fact, a user should be able to access services with the same quality of any other pupil, independently from his location and period of the day. This, of course, can not be fulfilled in case of bandwidth limitations and can be very restrictive in remote cooperative applications, where even real-time interactions may become inefficient.
Of course, only further technological advances will fill the gap of the digital divide. Nevertheless, the following considerations can be made: (1) a workgroup activity is composed by subtasks, each requiring a minimal bandwidth guaranteed; the overall work can be optimized through a proper definition of such tasks; (2) people within a group can be assigned different tasks according to their network capabilities in terms of bandwidth; (3) workgroup continuity can be preserved if users (as singles and as a group) are assigned an adequate minimum bandwidth guaranteed.
The proposed architecture for cooperative learning is based on QoS (Quality of Service) management and activities’ scheduling. The applied scheme adopts priority-based dynamic access profiles for bandwidth optimization in QoS multimedia services.
This kind of profile management allows to asssign different priorities to distinct applications, so as to rearrange service quality in a dynamic way and guarantee the desired performance to a given data flow.
A centralized platform and main QoS server manage several distributed sites and further QoS servers. Each site is connected to the main one through a link with a minimum bandwidth guaranteed and maximum available.
A distributed database stores information about mobile users, their current sites, priorities, group membership, etc.
In order to fulfill requirements 1-3, the platform allows to define macro activities and subtasks (“atomic tasks”), each assigned to one or several people and requiring a given bandwidth. The system evaluates each task’s bandwidth needs and, depending on the people involved and their network access capabilities, assigns the task or suggests better combinations. Once tasks have been arranged, each QoS server optimizes their execution assigning priorities to the users involved.
Each QoS server coordinates some of the atomic tasks of each macro activity, through each user’s traffic allocation and priority assignment, as required by the configurations of atomic tasks.
Consider for instance three users A, B, C, where A and B (group1) are expected to take part to a videoconference; the same applies to B and C as members of group2. The traffic of one of the groups can be slown down in case the other has a higher priority, such as a more urgent task to discuss respect to the overall process.
Further work will be devoted to a more detailed definition of group membership, not only with respect to network capabilities, but also to each person’s specific needs and skills.

Keywords:

E/m-learning, workgroup, digital divide, bandwidth, QoS management.