Evaluating the impact of data transfer time and mobility patterns in opportunistic networks

The Epidemic protocol is an effective way to achieve information diffusion in opportunistic networks. Its performance depends on two key factors: the device mobility pattern, and the message transmission time. The mobility pattern determines the contact time and duration. If contact durations are shorter than the required transmission times, some messages will not get delivered, and the whole diffusion scheme will be seriously hampered. In this paper we evaluate the impact of message transmission times in epidemic diffusion processes. We demonstrate how, when certain conditions hold, forcing devices to stop moving to complete the data delivery process can improve their performance. We implemented this mobility model, called Forced Stop, in the ONE (Opportunistic Networking Environment) simulator, and we show that, for large message sizes, the diffusion performance is increased. These results can be a relevant indication to the designers of opportunistic networks applications that could integrate in their products strategies to inform the user about the need to temporarily stop to increase the overall data delivery.