Implementing secure network-assisted D2D framework in live 3GPP LTE deployment

Device-to-Device (D2D) communication constitutes an emerging network paradigm that promises to unlock decisive capacity gains without the need for expensive cellular resources. However, while deployment of this promising enabler technology in 5G-grade mobile networks is currently underway, the complete understanding of feasible use cases and their respective limitations has not yet been provided in literature. Today, employing D2D connectivity both in human-to-human and machine-tomachine scenarios, the attention of research community focuses on security, privacy, and trust. Inspired by this increasing demand, we provide in this paper a comprehensive summary on our live trial of secure cellular-assisted D2D communication technology within the full-featured 3GPP LTE network deployment. Correspondingly, we describe a novel D2D framework capable of delivering secure direct connectivity even if the managing cellular link is temporarily not available (unreliable), so that communicating devices could continue to exchange confidential data in their private coalitions. To this end, our prototype implementation characterizes the practical capabilities of secure D2D communication in dynamic, urban environments suffering from intermittent 3GPP LTE connectivity.