Disruption-Tolerant Spatial Dissemination

Spatial dissemination is a specific form of information dissemination that enables mobile users to send information to other mobile users who are or will appear at a specific location (a user-defined region). Such geo-messaging services are on the rise; they typically are built upon centralized solutions and require users to have reliable access to a stable backend infrastructure for storing and communicating content. In this paper, we develop a distributed solution to spatial dissemination, that can work without the need for such an infrastructure. Our solution utilizes the concepts from disruption-tolerant networking to build a flexible/best-effort service that leverages the intermittent ad-hoc connectivity between users. We propose Sticker, a spatial dissemination protocol that aims to maximize delivery reliability without incurring significant storage/transmission overheads. Sticker employs the store-carry-and- forward model, and strives to optimize dissemination performance by addressing three sub-problems - replication, forwarding and purging. Our experiments show that, Sticker achieves delivery ratios that are close to the maximum possible values; as compared to existing techniques, it either cuts down storage/transmission overheads by over 50%, or greatly enhances both delivery reliability and storage efficiency.