F3-O/LT2-2 - Internet of Things network infrastructure for the educational purpose

1. Innovative Practice Full Paper
Piotr Czekalski1 , Krzysztof Tokarz1, Raivo Sell2, Salvatore Distefano3, Riccardo Di Pietro3, Giovanni Merlino3, Carlo Scaffidi3, Godlove Suila Kuaban4, Gabriel Drabik1, Jarosław Paduch1
1 Silesian University of Technology, Faculty of Automatic Control, Electronics, and Computer Science
2 Tallinn University of Technology
3 University of Messina
4 Institute of Theoretical and Applied Informatics, Polish Academy of Sciences

In this full paper, we present the results of the work that has been done to create standardization and innovative methods and tools for teaching the Internet of Things topics — the international project named IOT-OPEN. Partners from five countries have implemented it, and one of the goals of the project was to create distributed, remote and distant access laboratory infrastructure, accessible using a WEB browser only, virtually from any place in the World. From the technical point of view, the user is given a WEB interface, a browser-based IDE, where one can enter, compile and remotely upload their solution to the device, yet it can parallel observe the laboratory node and its physical output via web cameras. Each node is equipped with at least one camera, while some of them have more, depending on the number of scenarios they implement and their physical construction. 

Placement of the remote laboratory equipment in different countries needed the carefully designed network infrastructure and software for both laboratory equipment and servers. Educational IoT infrastructures shall provide both securities as well as the flexibility of the implementation scenarios; thus, it affects the networking design strongly. Moreover, assuming that laboratories are shared among various developers, it is essential to provide a usage model like i.e. shared node, an exclusive lock on a single node or in complex scenarios, an exclusive lock for the users on many infrastructure devices. 

Providing remote, limited access to the hardware and services limits possible threats but also may limit possible scenarios. It is essential to balance between security-driven limitations and flexibility on usage scenarios when preparing the educational IoT solution. Assuming our considered IoT laboratory infrastructure has remote access only, for both developers and users, one of the critical challenges is to provide a hardware solution that is maintenance-free on the development stage and on the usage stage as well.

Currently, the IoT devices and solutions, including the presented educational laboratory, show a high level of heterogeneity that creates the need to use many network technologies and protocols. Additionally, some network technologies better support the short packets while others allow transmitting data at a higher speed. The system presented in the article utilizes the wired ethernet network as the backbone and as the reliable transmission medium that connects main Raspberry Pi controllers of every remote laboratory station. Additionally, two WiFi APs are implemented to allow connecting the high number of wireless sensor/actuator devices. All are supplied with communication brokers, securely routing IoT messages between end-nodes, even in different countries. The proposed network structure answers the need for a reliable IoT laboratory that could be used remotely by students from other time zones and should be operable continually whole the day. It also ensures the flexibility of various wireless nodes configuration for local laboratory usage. In this system, the fog class IoT devices are used as the nodes that offer resources sufficient to implement an IP-based network and proxy end-node IoT devices with sensors and actuators.