1. 11/14/ 2006ICNP 20061 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

2. 11/14/ 2006ICNP 20062 Sensor Networks Sink

3. 11/14/ 2006ICNP 20063 Geocasting in Sensor Networks end users query response sink sensor

4. 11/14/ 2006ICNP 20064 Existing Approaches: Restricted Flooding

5. 11/14/ 2006ICNP 20065 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.

6. 11/14/ 2006ICNP 20066 RFIFT Basic s Some concerns: Cost Potential collision Delivery speed

7. 11/14/ 2006ICNP 20067 Another Problem in RFIFT s Region u y In some cases, RFIFT needs to be modified to guarantee message delivery y z

8. 11/14/ 2006ICNP 20068 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!)

9. 11/14/ 2006ICNP 20069 Virtual Surround Face (VSF) u v

10. 11/14/ 2006ICNP 200610 Example of VSF Geocasting s u w

11. 11/14/ 2006ICNP 200611 Termination Condition y s Region g MSG 1 MSG 2 h f MSG 1 (h, Right) MSG 2 (f, Left)

12. 11/14/ 2006ICNP 200612 v y Special Case 1 in VSFG Boundary of VSF connected via internal nodes z & t s Region x u w t g z Component 2 Component 1

13. 11/14/ 2006ICNP 200613 Special Case 2 of VSFG VSF connected via external crossing edge yu v s Region x u w y z Component 2 Component 1 g

14. 11/14/ 2006ICNP 200614 Special Case 2 in RFIFT RFIFT has much longer delivery time s Regionx u 34 time slots in RFIFT vs 12 time slots in VSFG

15. 11/14/ 2006ICNP 200615 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.

16. 11/14/ 2006ICNP 200616 Simulation Setup Two types of simulated networks –Random network: randomly deployed node in a 20  20 square 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 voidsVoid network with 30 voids

17. 11/14/ 2006ICNP 200617 Simulation Results: Random Network Average degree of network Face traversal cost (Thousands) Total cost of geocasting (Thousands) Average degree of network Face traversal cost (Thousands) Total cost of geocasting (Thousands) Costs for base networks with 5  2.5 geocasting regions Costs for base networks with 3  1.5 geocasting regions

18. 11/14/ 2006ICNP 200618 Simulation Results: Void Network Average degree of network Cost of geocasting (Thousands) Cost of geocasting (Thousands) Void networks with 15 voids and 3  1.5 regionsVoid networks with 30 voids and 3  1.5 regions 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

19. 11/14/ 2006ICNP 200619 Conclusion Design of VSF Guaranteed message delivery Fast delivery due to concurrent double directional traversal Low transmission cost Low probability of collision occurrences Scalability

20. 11/14/ 2006ICNP 200620 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.

21. 11/14/ 2006ICNP 200621

22. 11/14/ 2006ICNP 200622 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 MSG 1 (v, Rule 1 ) but not been forwarded to next node yet. –Node u receives another traversal message MSG(w, Rule 2 ). Termination Condition –If the next visited node of MSG 1 is w; –If the next visited node of MSG 2 is v; –If Rule 1 is not same as Rule 2 ; –Node u terminates the face traversal (discards MSG 1 and MSG 2 ).

23. 11/14/ 2006ICNP 200623 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)

24. 11/14/ 2006ICNP 200624 Planar Graphs UDG GG RNG UDel  Two nodes can find if they are RNG/GG neighbors By their local knowledge. However nodes can not do the same thing in UDel.

25. 11/14/ 2006ICNP 200625 Face and Face Traversal in GG Four faces: F 1, F 2, F 3, and F 4, where F 4 is an exterior face (open area) Traversing F 1 by using Right-Hand rule starting from u v F3F3 F1F1 F4F4 u z w x y F2F2 u1u1 u2u2 u3u3 u5u5 u6u6 u7u7 u8u8 u9u9 u 10 u 11 u 12 u 13 v1v1 v2v2 v4v4 v3v3 u4u4

26. 11/14/ 2006ICNP 200626 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.