1. A NOVEL SOCIAL CLUSTER-BASED P2P FRAMEWORK FOR INTEGRATING VANETS WITH THE INTERNET Chien-Chun Hung CMLab, CSIE, NTU, Taiwan

2. OUTLINE Introduction Social cluster-based overlay structure Lifetime-aware flooding scheme Connectivity-aware retrieval scheme Performance Evaluation Conclusions

3. INTRODUCTION Non-safety related applications in VANETs o Improve driving comfort o Provide interesting entertainment services Two different types of communications: o Inter-Vehicle Communication o Roadside-to-Vehicle Communication Two important elements defined in VII (Vehicle Infrastructure Integration): o RSU(Road Side Unit) o OBU(On Board Unit)

4. INTRODUCTION Peer-to-peer(P2P) system: o Efficiently access different types of data o Leverage each peer’s resource o Reduce the load of original content provider Main components of P2P system: o Resource discovery scheme o Resource retrieval scheme

5. INTRODUCTION Goal: To design a P2P framework for hybrid network(VANET and Internet) o Fixed peer: original peers in thee Internet o Mobile peer: moving vehicles o Challenge: Enable mobile peers to request and retrieve resource efficiently according to connectivity and environment

6. INTRODUCTION Framework: Interest-based clustering to group similar peers into a cluster: 1.Social cluster-based overlay structure  To eliminate discovering overhead through the RSU 2.Lifetime-aware flooding scheme  To eliminate request storm among mobile peers 3.Connectivity-aware retrieval scheme  Take lifetime and bandwidth into consideration to select the best peer

7. OUTLINE Introduction Social cluster-based overlay structure Lifetime-aware flooding scheme Connectivity-aware retrieval scheme Performance Evaluation Conclusions

8. SOCIAL CLUSTER-BASED OVERLAY STRUCTURE Goal: to eliminate the overhead of finding mobile peers. o Group mobile peers and fixed peers into clusters. o Peers with similar interests are group into a cluster. ______

9. SOCIAL CLUSTER-BASED OVERLAY STRUCTURE Interest-based intra-cluster construction o One fixed peer and several mobile peers o Mobile peer picks the cluster whose cluster head has the most similar interest with it o Fixed peer acts as the cluster head and maintains file indexes of its cluster

10. SOCIAL CLUSTER-BASED OVERLAY STRUCTURE Small-world-based inter-cluster construction o Random walk to reach into different clusters o To increase the ratio of resources that can be found Peers can use overlay to effectively discover resources by requesting the cluster.

11. OUTLINE Introduction Social cluster-based overlay structure Lifetime-aware flooding scheme Connectivity-aware retrieval scheme Performance Evaluation Conclusions

12. LIFETIME-AWARE FLOODING SCHEME Social cluster-based overlay o Enable mobile peers to discover resources in clusters (through RSUs) Lifetime-aware flooding scheme  Help mobile peers to efficiently discover resources through VANETS Connection lifetime must be taken into consideration.

13. LIFETIME-AWARE FLOODING SCHEME

15. OUTLINE Introduction Social cluster-based overlay structure Lifetime-aware flooding scheme Connectivity-aware retrieval scheme Performance Evaluation Conclusions

16. CONNECTIVITY-AWARE RETRIEVAL SCHEME If a mobile peer requests too many blocks at once, it might waste bandwidth. The path quality between two peers must be considered in order to decide how to retrieve data. o Path lifetime o Path bandwidth

17. CONNECTIVITY-AWARE RETRIEVAL SCHEME

18. OUTLINE Introduction Social cluster-based overlay structure Lifetime-aware flooding scheme Connectivity-aware retrieval scheme Performance Evaluation Conclusions

19. PERFORMANCE EVALUATION Network simulator 2 (NS2) Geographic Information System (GIS) 200 fixed nodes in 3000m * 3000m 802.11n standard MAC protocol Transmission range: 250m Transmission rate: 27 Mb/sec 83 kinds of data, 31005 files

20. PERFORMANCE COMPARISON SCHEMES Gnutella Interest-based P2P scheme Network-based P2P scheme CarTorrent Social Cluster-based P2P scheme

21. PERFORMANCE EVALUATION QUERY HIT RATIO VS. RSU NUMBERS 200 mobile peers Each has 50 cached files

22. PERFORMANCE EVALUATION RATIO OF RETRIEVING FILES VS. NUMBER OF RSUS

23. PERFORMANCE EVALUATION MESSAGE OVERHEAD VS. NUMBER OF RSUS

24. PERFORMANCE EVALUATION QUERY HIT RATIO VS. CACHED FILES

25. OUTLINE Introduction Social cluster-based overlay structure Lifetime-aware flooding scheme Connectivity-aware retrieval scheme Performance Evaluation Conclusions

26. CONCLUSIONS Design a P2P system that can integrate VANETs and the Internet o Social cluster-based overlay structure o Lifetime-aware flooding scheme o Connectivity-aware retrieval scheme Our work achieves higher discovering rate and retrieving speed than existing schemes.