Jie Lian, Kshirasagar Naik University of Waterloo, ON, Canada Yunhao Liu, Lei Chen

1. Virtual Surrounding Face Geocasting with Guaranteed Message Delivery for Ad Hoc and Sensor Networks Jie Lian, Kshirasagar Naik University of Waterloo, ON, Canada Yunhao Liu, Lei Chen The Hong Kong University of Science and Technology, Hong Kong, China ICNP 2006

2. Sink Sensor Networks ICNP 2006

3. Geocasting in Sensor Networks query sink end users response sensor ICNP 2006

4. Existing Approaches: Restricted Flooding ICNP 2006

5. Existing Approaches • Approaches with delivery guarantee • DFFTT: Depth-First Face Tree Traversal • RFIFT: Restricted Flooding with Intersected Face Traversal • EZMG: Entrance Zone Multicasting-based Geocasting • Drawbacks :Complex, longer delivery time, high message cost, potentially series contention. ICNP 2006

6. RFIFT Basic • Some concerns: • Cost • Potential collision • Delivery speed s ICNP 2006

7. Another Problem in RFIFT • In some cases, RFIFT needs to be modified to guarantee message delivery y Region z u y s ICNP 2006

8. Our Goals • Guaranteed message delivery • Short delivery time • Low transmission cost • Avoid potential message collisions • Reducing message complexity of RFIFT: • (3n +k)  2n+k (hopefully!) ICNP 2006

9. Virtual Surround Face (VSF) u v ICNP 2006

10. Example of VSF Geocasting w u s ICNP 2006

11. MSG2(f, Left) MSG2 MSG1(h, Right) MSG1 Termination Condition f g Region h y s ICNP 2006

12. Special Case 1 in VSFG • Boundary of VSF connected via internal nodes z & t v w x u g t Region z y Component 1 Component 2 s ICNP 2006

13. Special Case 2 of VSFG • VSF connected via external crossing edge yu w v x u Region g Component 2 Component 1 y z s ICNP 2006

14. Special Case 2 in RFIFT • RFIFT has much longer delivery time Region x u s 34 time slots in RFIFT vs 12 time slots in VSFG ICNP 2006

15. Asymptotical bound of VSFG • The message complexity of VSF traversal is bounded by 2n, where n is the number of nodes located on VSF boundary. • The message complexity of face traversal in RFIFT is bounded by 3n. ICNP 2006

16. Simulation Setup • Two types of simulated networks • Random network: randomly deployed node in a 20  20square area. • Void network: From random networks, a number of 1.5  1.5 square voids are randomly generated and all nodes within voids are removed. • Geocasting region: randomly generated rectangular regions • Performance metric: number of messages required Void network with 15 voids Void network with 30 voids ICNP 2006

17. Simulation Results: Random Network Costs for base networks with 3  1.5 geocasting regions Face traversal cost (Thousands) Total cost of geocasting (Thousands) Average degree of network Average degree of network Costs for base networks with 5  2.5 geocasting regions Face traversal cost (Thousands) Total cost of geocasting (Thousands) Average degree of network Average degree of network ICNP 2006

18. Simulation Results: Void Network VSF-C: total cost of VSFG VSF-Cf: face traversal cost of VSF IFT-C: total cost of RFIFT IFT-Cf: face traversal cost of RFIFT Cost of geocasting (Thousands) Cost of geocasting (Thousands) Average degree of network Average degree of network Void networks with 15 voids and 3  1.5 regions Void networks with 30 voids and 3  1.5 regions ICNP 2006

19. Conclusion • Design of VSF • Guaranteed message delivery • Fast delivery due to concurrent double directional traversal • Low transmission cost • Low probability of collision occurrences • Scalability ICNP 2006

20. Future Work • Reducing face traversal cost by designing shortcut algorithm • Designing localized dominating-set based flooding algorithm to replace restricted flooding in VSFG. • Analyzing the impact of location errors on VSFG and providing respective solutions. • Studying VSFG on realistic network model, not unit disk graphs. ICNP 2006

21. ICNP 2006

22. Termination Condition • Observation • When a node starting a VSF traversal by using Right- and Left-hand simultaneously, the two traversal messages with eventually meet at a node on the boundary VSF. • Precondition • A VSF node u receives a traversal message from node v MSG1(v, Rule1) but not been forwarded to next node yet. • Node u receives another traversal message MSG(w, Rule2). • Termination Condition • If the next visited node of MSG1 is w; • If the next visited node of MSG2 is v; • If Rule1 is not same as Rule2; • Node u terminates the face traversal (discards MSG1 and MSG2). ICNP 2006

23. Unit Disk Graph and Planar Graph • Unit disk graph (UDG) • Identical transmission range, which is treated as unity. • Two nodes are neighbors if their distance is less than 1. • Simplified network model • Planar graph • A graph without two edges crossing one another • Example planar graphs deduced from UDG: • Relative neighborhood graph (RNG) • Gabriel graph (GG) • Unit Delaney Triangulation (UDel) ICNP 2006

24. Planar Graphs UDG Two nodes can find if they are RNG/GG neighbors By their local knowledge. However nodes can not do the same thing in UDel. GG UDel RNG   ICNP 2006

25. Face and Face Traversal in GG • Four faces: F1, F2, F3, and F4, where F4 is an exterior face (open area) • Traversing F1 by using Right-Hand rule starting from u u4 u2 u3 F4 u5 v1 u1 F3 u v2 u6 F2 v4 v z v3 u12 F1 u7 w u11 y u13 u10 u8 u9 x ICNP 2006

26. VSF Geocasting • VSF Forwarding • A source node s selects a geographical point in a geocasting region closest to the source node as the destination reference point p. • Node s transmits a geocasting message towards p by using location-based routing until a node u on the boundary of the VSF is found. • VSF Traversal (Double direction traversal) • Node u as chosen above starts VSF traversal using Right-hand rule and Left-hand rule simultaneously. • VSF Restricted Flooding • Each node in the geocasting region overhearing a geocasting message for the first time broadcasts the message. ICNP 2006