Bubble Rap: Social-based Forwarding in DTNs Pan Hui, Jon Crowcroft, Eiko Yoneki University of Cambridge, Computer Laboratory Slides by Alex Papadimitriou

Bubble Rap: Social-based Forwarding in DTNs Pocket Switched Networks (PSNs)  Human mobility in terms of social structures  Multitude of devices carried by people are dynamically networked.  A PSN uses contact opportunities to allow humans to communicate without network infrastructure. Within a community some people are more popular and interact with more people than others (have high centrality), we call them hubs. Betweenness Centrality measures the number of times a node falls on the shortest path between two other nodes.  Represents the importance of a node as a potential traffic relay for other nodes in the system.

Bubble Rap: Social-based Forwarding in DTNs Experimental Datasets:  Infocom05, Hong Kong, Cambridge, infocom06, reality. Two intuitions:  People have varying roles and popularities in society. The first part of the forwarding strategy is to forward messages to nodes which are more popular than the current node.  People form communities in their social lives. The second part of the strategy is to identify the members of destination communities and to use them as relays. Assumptions:  Each node belongs to at least one community.  Each node has a global ranking across the system and a local ranking for its local community. It may belong to multiple communities and have multiple local rankings.

Bubble Rap: Social-based Forwarding in DTNs Algorithm:  The sender node first bubbles the message up the ranking tree using the global ranking, until it reaches a node which is in the same community as the destination node.  Then the local ranking is used. The message bubbles up the through the local ranking until the destination is reached or the message expires. The node needs to be able to compare rankings with nodes encountered and to push the message using a greedy approach. Whenever a message is delivered to the community, the original carrier can delete this message from the buffer.

Bubble Rap: Social-based Forwarding in DTNs Real Life:  First you try to forward the message via surrounding people more popular than you (politician), and then you bubble it up to well-known popular people in the wider-community (postman).

Bubble Rap: Social-based Forwarding in DTNs