Human-mobility enabled wireless networks for emergency communications during special events

During social gatherings or emergency situations, infrastructure-based communication networks have difficulty operating given either increased traffic demand or possible damage. Nevertheless, current communication networks still rely on centralized networking paradigms. The adoption of a peer-to-peer communication paradigm would be better adapted to these needs, especially if it relies on the mobile phones that people normally carry, since they are automatically distributed where the communication needs are. However a question arises: can the spatio-temporal distribution of mobile phones enable a partially-connected ad hoc network that allows emergency communications to happen with an acceptable delay? To try to answer this question, we defined a methodology composed of three steps. First, the positions of seven hundred humans, spread over a metropolitan area, have been anonymously traced during a special gathering event. Then, with a multi-disciplinary approach, we have inferred the contact events from the humans' traces. Finally, we have assessed the effectiveness of an ad hoc network established by the mobile phones to disseminate emergency information to the population in a timely fashion. The results reveal that the humans' mobility can effectively enable emergency communications among a significant subset of mobile phones, although the connectivity of the network strictly depends on the number of cooperating devices and on the maximum allowed delay. (C) 2012 Elsevier B. V. All rights reserved.