Abstract:

Wireless sensor networks consist of autonomous intelligent sensor nodes, usually powered by battery, that can measure certain characteristics of their environment, such as temperature, pressure, moisture, acceleration, etc. These sensor nodes communicate by radio with their neighbours to forward data to a central collection points from where it is sent to some analysis centre via the Internet. The use of batteries and radio communications minimizes the cost. Wireless sensor networks have a broad range of applications: climate monitoring, seismic monitoring, early detection of bush fires, power usage optimization in buildings, etc. A major concern is the lifetime of batteries. As most of the energy is used for radio transmission, many research efforts have focused on the development of communication protocols that minimize power. Wireless Sensor Networks fit in the broader category of “smart object networks” that are gaining attention as the large range of IPv6 addresses will make possible “the Internet of Things”, heralded for a long time but still blocked by the lack of a suitable address space. In this perspective the Internet Engineering Task Force (IETF) has created a working group in charge of the design of a new routing protocol for low power and lossy networks. This working group has extensively studied the requirements and made a detailed proposal, called RPL, still to be considered as work in progress, as very little practical experience with implementing it is available.
The authors are regularly faced with masters students interested in wireless sensor networks as a research topic for their thesis, but not knowing enough about it to make a rational choice. Teaching quickly these basics to individual potential students appeared to be a time consuming, rather inefficient, task.
It has been observed that students, who have the opportunity to experiment freely with systems they need to understand, learn faster and more in depth than those who do not have such opportunities. For that reason, a very simple, user friendly, interactive simulator that exposes the underlying principles of the Distance Vector (DV) and the Ad-hoc, On Demand Distance Vector (AODV) protocols has been developed and is being evaluated with master’s students. It does not replace in any sense the more sophisticated simulation environments that are available to researchers. On the contrary, it is used to clarify basics of routing and to trace messages through real networks before confronting the students with the fully fledged simulation packages. The first version of this simulator is now used as a support for lectures on routing and as a self-teaching tool for students considering a master’s thesis in two universities one in Europe and one in Africa. The Java source code of specific parts is also being used as starting point for some student assignments in courses on protocol implementation.
In a second version, the much more complex RPL protocol has been added, requiring only minor changes to the original Java code. The didactic value of this new version is being evaluated with the participants of an international summer school for engineering students.
In this paper, the decision to build a didactic tool rather than adapting existing tools is motivated and the design issues are discussed, with emphasis on RPL. The results of the evaluation of the didactic qualities by various groups of students in different educational contexts will also be presented.

Keywords:

Didactic tools.