On the Resilience of D2D-Based Social Networking Service against Random Failures

Device-to-device (D2D)-based social networking service (SNS) is an emerging information system that enables users with social ties to exchange multimedia contents through multihop short-range wireless links. In the D2D-based SNS, a random initial node failure may lead to a cascade of failures, which is a series of events in which users become isolated from others over subsequent time instances. Different from previous studies that analyze whether network-wide connectivity can be preserved after a cascade of failures, our study sheds light on the D2D-based SNS's resilience from the perspective of end-user connection experience. In this paper, we first introduce a numerical method for calculating the mean fraction of nodes that are not affected by the cascading failures and the amount of time to reach the end of such sequence of failures. Then, we apply a probabilistic approach to derive the lower and upper bounds of a node resilience metric, which is the likelihood that an end-user will not be isolated during an ongoing social networking session. Our analysis and numerical simulations indicate that, compared to exponentially-distributed session times, user session times with Pareto (heavy-tailed) distribution results in poorer node resilience, which quickly deteriorates when the mean session time is high.