http://hdl.handle.net/2268.2/1966 Sat, 17 Oct 2026 18:00:46 GMT 2026-10-17T18:00:46Z http://hdl.handle.net/2268.2/4702 Title: Ad-hoc communication for mobile devices Abstract: Nowadays, most networked mobile applications are built following a client-server architecture. In this paradigm, communications between devices are relayed through a centralized infrastructure. This technique has the disadvantage of requiring the presence of a centralized access point and depends entirely on it, which involves network delay and limits mobility. These limitations can be avoided by using an ad hoc model which allows direct communications between mobile devices. Since ad hoc architecture is less widespread than centralized architecture, fewer resources are proposed for developing ad hoc applications. This master thesis presents the conception and the implementation of a library to facilitate the management of ad hoc networks amongst mobile devices. The library is implemented as a middleware component on the Android platform and is designed according to a layered model where each layer provides specific services. Bluetooth and Wi-Fi Direct technologies are used to establish ad hoc communications. Nevertheless, the main limitation of Wi-Fi Direct is that it does not support multi-hop communications. To overcome this limitation, the library proposes a hybrid approach by using Bluetooth technology to interconnect several Wi-Fi Direct groups. The proposed scheme provides an abstraction layer that handles multi-hop communications independently of the underlying wireless technology and uses the Ad hoc On-demand Distance Vector (AODV) routing protocol. All these mechanisms are encapsulated and are provided as high level APIs to manage ad hoc communications in a convenient way. Finally, this master thesis provides several proof of concept applications which use the library, a brief performance analysis and gives a conclusion about the work accomplished as well as some suggestions of improvement. Sun, 24 Jun 2018 22:00:00 GMT http://hdl.handle.net/2268.2/4702 2018-06-24T22:00:00Z http://hdl.handle.net/2268.2/4691 Title: Design of a secure IoT gateway configuration and data visualisation web application Abstract: Nowadays, information technology is everywhere. Smartnodes, an innovative spin-off of the University of Liège, is currently developing the concept of smart cities. Its developers have designed a light controller which is able to follow the movements of the road users and create a bubble of light around them. To do so, they place, on the street lamps, several systems called nodes that embed sensors in order to collect data from a street area. A central system, composed of a Raspberry Pi, serves as a gateway to manage the operations and the synchronizations between the nodes. However, the only existing solution to configure a gateway or to visualize some data about the nodes is to connect to it with a terminal and the SSH protocol. Therefore, the goal of this master thesis is to make this process more intuitive by developing an ergonomic responsive web application and to deploy it in each gateway. After comparing the different web technologies, the ones that fit the best for this project was Python with the Django framework for the server side, HTML/CSS/JavaScript with Bootstrap and jQuery libraries for the client side and Nginx for the web server. Moreover, the solution proposed is secured against principle types of attacks and all communications between the client's browser and the server are encrypted by using the HTTPS protocol. Finally, as the number of gateways may be very big and will increase with the time, the testing and the deployment processes must be the easiest as possible. Thus, some unit tests have been written and a script that automates the installation of the Django web application and all its dependencies has been implemented. Sun, 24 Jun 2018 22:00:00 GMT http://hdl.handle.net/2268.2/4691 2018-06-24T22:00:00Z http://hdl.handle.net/2268.2/4612 Title: Implementing Video Broadcast Specific Functions into next-generation user-programmable ASIC Abstract: With the evolution of live video productions, the IP technology leaves some challenges and room for optimization. Using cutting-edge user-programmable ASIC switch, it is possible to put complexity inside the network that releases endpoints with more computations. This master thesis explores the capabilities of the Tofino ASIC created by Barefoot Networks to directly optimize Broadcast IP flows using the P4 programming language. A switch improved with the functionalities explored could replace traditional switches with a focus on quality in the final render. First, this work details a video clean switching functionality entirely performed in the network. In a second step, the replication of multicast flows is also possible in a short and quantified amount of time. To conclude, programs were created for the welcoming company and tests were created to evaluate performances and usability of telemetric functionalities. A new data collection protocol was defined and tested to collect metadata. Exploitation cases of those metrics were explored. This work consists in the first stage in using built-in packet replication, performing complex NAT switching, and understanding the telemetry capabilities of a programmable data plane. Sun, 24 Jun 2018 22:00:00 GMT http://hdl.handle.net/2268.2/4612 2018-06-24T22:00:00Z http://hdl.handle.net/2268.2/4562 Title: Wind correlation analysis between Greenland and Europe Abstract: This article is dedicated to the development of computational methods for processing time series from wind speed signals. These computational methods are designed under the light of electricity generation from this intermittent renewable source. We propose to define the notion of critical time windows for measuring the proportion of the time during which renewable energy fields may simultaneously not produce sufficiently, i.e., with a load factor lower than a predefined threshold. Using this type of criterion opens the door to expressing optimization problems describing how to choose the localizations where to install production capacities. The proposed methodology is benchmarked using wind time series data from Europe and Greenland. In this document, two sets of time series are considered: the first one was generated using the MERRA-2 from NASA, while the second one was generated using the MAR model, a regional model taking into account Katabatic winds. First experimental results illustrate the fact that connecting Western Europe with Greenland may effectively decrease the proportion of critical time windows. Sun, 24 Jun 2018 22:00:00 GMT http://hdl.handle.net/2268.2/4562 2018-06-24T22:00:00Z