Effective Dissemination of Presence Information in Highly Partitioned Mobile Ad Hoc Networks

Presence technology enables users of an instant messaging (IM) system to determine if their contacts are online and ready to communicate. In this paper, we propose an effective approach for the proactive dissemination of frequently changing presence information in highly partitioned mobile, wireless networks with IEEE 802.11 technology. Although communication techniques for intermittently connected networks have been extensively studied in the field of delay tolerant networking, the fact that presence information is highly delay sensitive requires a thorough revision of these techniques. To this end, we use discrete-event simulation based on a high-level stochastic model of the IM system to compare different approaches for disseminating presence information in terms of sustained consistency (i.e., fraction of time presence information is in a coherent state) and traffic requirements. Building upon the outcome of the simulation study, we propose the system for presence information exchange by epidemic dissemination (SPEED). Results of a detailed ns-2 simulation study show that SPEED outperforms an approach based on optimized flooding by up to 20% in terms of sustained consistency for low node density and saves up to 48% of control traffic for medium to high node density