NETCOM Research Group

Context-awareness is a peculiar characteristic of an expanding set of applications that make use of a combination of restricted spatio-temporal locality and mobile communications, to deliver a variety of services. Opportunistic communications satisfy well the communication requirements of these applications, because they naturally incorporate context. Recently, an opportunistic communication paradigm called "Floating Content" was proposed, to support infrastructure-less, distributed content sharing. It aims at ensuring the availability of data within a certain geographic area called anchor zone. In literature, the focus was on understanding the asymptotic properties of the floating lifetime, i.e. the duration of time for which content floats in the anchor zone. Instead, our objective is to characterize the performance of context-aware applications using floating content as a communication service.

In the first part of the thesis we present a simple approximate analytical model for accessing the viability of floating content to act as a communication service for context-aware applications. We focus on the "success probability", which captures the likelihood for a user to receive the content when traversing the anchor zone and apply our analysis to estimate the success probability for three representative categories of context-aware applications, and show how the system can be configured to achieve the application's target.

In the second part of the thesis, we investigate the impact of different mobility models on the performance of context-aware applications that use floating content. In particular, we consider four different mobility models, and, by using extensive simulation experiments, we investigate the performance of three different categories of context-aware applications. By comparing the simulation results to the performance predictions of our previously proposed simple analytical model, we show that our model can provide useful performance predictions even for complex and realistic mobility models. Simulation results under different mobility models also confirm the viability of floating content to act as a communication service for a variety of context-aware applications.

In the final part of the thesis we investigate the performance of floating content in a real world setting by developing and deploying an Android mobile application based on floating content in an office and a university campus environment. To the best of our knowledge, this is the first ever experimental evaluation of floating content service in a real setting. Our results provide quite interesting indications for the viability and the implementation of applications using floating content in the considered environments. We also propose a novel simple analytical model that accounts for the peculiarities of the mobility patterns in such a real world setting, and that can accurately predict the effectiveness of floating content for the implementation of context-aware applications in an office and a campus setting.

About Shahzad Ali

I am currently a PhD Student at the IMDEA Networks Institute and a PhD candidate in Telematics Engineering at University Carlos III of Madrid under the supervision of Marco Ajmone Marsan, Gianluca Rizzo, and Vincenzo Mancuso. I received a BS and a MS degree in Computer Science from the COMSATS Institute of Information Technology Abbottabad, Pakistan in 2007 and 2009 respectively, and a MsC in Telematics Engineering from the University Carlos III of Madrid (UC3M) in 2011.

The thesis defense will be conducted in English