Tradeoffs between trust and survivability for mission effectiveness in tactical networks

In a military tactical network, maintaining trust among members in a mission group is critical to successful mission completion. However, maintaining high trust among group members in a resource-restricted tactical environment detrimentally reduces system lifetime, which may lead to mission failure or low mission effectiveness. In this paper, we aim to investigate the relationships between group trust and system lifetime [i.e., survivability measuring mean time to mission failure (MTTMF)] and to capture mission effectiveness achieved by the mission group based on the tradeoff between these two goals. We employ a composite trust capturing various angles of trust concept derived from communication, information, and social networks. We take a game theoretic approach using the so called Aoyagi's game theory, enforcing nodes to exhibit desirable behavior based on reward or penalty given by the system. In designing reward/penalty mechanisms, we adopt the concept of aspiration level, defining success or failure based on a goal set by the system, and prove there exists an optimal trust threshold maximizing both MTTMF (i.e., system lifetime/survivability) and group trust. We devised a mission effectiveness metric based on both the metrics having conflicting goals. We developed an analytical model using Stochastic Petri Nets, and validated the analytical results with simulation results. We conducted comparative performance analyzes of the variations of the proposed scheme with respect to a node's decision nature (i.e., rational versus altruistic) and trust threshold policy (static versus dynamic) in resource-constrained tactical environments.