Time and Space in Android-Based Opportunistic Networks
Andre Ippisch, Tobias Kuper, Kálmán Graffi · 2018
Mobile devices like smartphones or other smart objects can create Opportunistic Networks with intermittent node contacts due to their wireless technology and their user's social behavior. In disaster, emergency and censorship situations, or if simply no internet connection is available, Opportunistic Networking can be used to connect devices to each other. We attempt to improve our Android-based network and take a look at time modification and buffer management issues. Syncing the time is a known problem due to the probable lack of a connection to the internet. Since the devices are user-controlled, changes in time have to be noticed and time differences between devices have to be exchanged. Also, we take a look at the special buffer which is not reserved entirely for the network but is shared with all applications on the device. For this paper, we developed functionality in form of multiple libraries to detect time changes and possible storage shortages on the devices, to synchronize time for our network, and to remove messages in a system in which there is not only one buffer but multiple virtual ones that belong to different applications. We conduct tests which detect when the Android system begins to notify about storage congestion and starts deleting buffer content. With these results, our libraries can improve the drop and queue policies that have to react before user data is deleted.