1. How small labels create big improvements Pan Hui Jon Crowcroft Computer Laboratory University of Cambridge

2. US-based Conferences In Memory of 9/11/01 We will never FORGET It IS Terrorists make USA government delaying visas for Asian people.

3. Outlines Community and forwarding in PSN Affiliations-based iMote Experiment LABEL : a community based forwarding Empirical results of community improves forwarding Conclusion

4. Community and Forwarding PSN: human mobile networks under DTN and MANET Naive forwarding schemes created unwanted traffics Identifying community information improve forwarding efficiency No empirical evaluation of this belief

5. Affiliations based iMotes Experiment Infocom 2006 Barcelona, Spain (not USA) 4 affiliation groups of 34 people 2 Paris groups, 1 Switzerland group, 1 Barcelona group Largest group of 15 people Carry the iMotes during the conference period iMotes log the contact with each other+other Bluetooth devices

6. Label Strategy (LABEL) Priori label, e.g. affiliation Correlated interaction Forward to nodes have same label as the destination Good performance in conference mixing environment USA soldiers Asian people Pretty Ladies LABEL: GOOD PEOPLE LABEL: BAD PEOPLE Destination : GOOD PEOPLE

7. Empirical Results

8. Problem with LABEL In a less mixing environment A person in one group may not meet members in another group so often Wait for destination group not efficient So smarter strategies make use of community information should be investigated

9. ICMAN2007, New York, China 19 March 2007 Conclusions Even very small amount of state information bring significant improvement in forwarding efficiency Need to embed state information in future design

10. ICMAN2007, New York, China 19 March 2007 Thank you ! http://www.cl.cam.ac.uk/~ph315/ Pan.Hui@cl.cam.ac.uk Jon.Crowcroft@cl.cam.ac.uk