Performance evaluation of hybrid disaster recovery framework with D2D communications Abstract   Public Safety Networks (PSNs) provide assistance before and postdisaster events. With the help of technological advances, PSNs are able to cope with both natural and manmade disasters, protecting people, environment and property. Effective communications, better situational awareness, lower response times and greater emergency efficiency are essential to an effective response to emergencies and disasters. Long Term Evolution (LTE) has been chosen to be the key technology for public safety networks. In this study, a performance model is presented for the PSN frameworks which use cooperative devices with LTE device to device (D2D) communications features. Mobile stations that are out of cellular network coverage range use D2D communications, where mobile stations which are in a healthy area can act as relay nodes to provide information about the location of potential victims to a central system. Since relay nodes have the potential to become bottlenecks for relatively high scale disasters, the interaction between the relay node and the base station is critically considered in this study. The analytical model and solution are suitable for assessing the quality of service for PSNs with similar infrastructures. Results obtained from the analytical model are presented comparatively with those from discrete event simulations for validation. The maximum discrepancy between the results obtained from the analytical model and the simulation results is less than 1.4%, which is within the confidence interval of the simulation.

Opportunistic multitechnology cooperative scheme and UAV relaying for network disaster recovery Disaster scenarios are particularly catastrophic in urban environments, which are very densely populated in many cases. Disasters not only endanger the life of people, but also affect the existing communication infrastructures. In fact, such an infrastructure could be completely destroyed or damaged; even when it continues working, it suffers from high access demand to its limited resources within a short period of time. This work evaluates the performances of smartphones and leverages the ubiquitous presence of mobile devices in urban scenarios to assist search and rescue activities following a disaster. Specifically, it proposes a collaborative protocol that opportunistically organizes mobile devices in multiple tiers by targeting a fair energy consumption in the whole network. Moreover, it introduces a data collection scheme that employs drones to scan the disaster area and to visit mobile devices and collect their data in a short time. Simulation results in realistic settings show that the proposed solution balances the energy consumption in the network by means of efficient drone routes and smart selforganization, thereby effectively assisting search and rescue operations.