1. ProgessFace: An Algorithm to Improve Routing Efficiency of GPSR-like Routing Protocols in Wireless Ad Hoc Networks Chia-Hung Lin, Shiao-An Yuan, Shih-Wei Chiu and Ming-Jer Tsai National Tsing Hua University, Taiwan IEEE Transaction on Computers (Accepted)

2. Outline Introduction The Virtual Neighbor Set Construction Protocol The ProgessFace Algorithm Performance Evaluation Conclusion

3. Introduction Greedy routing Concave node problem FACE routing The planar subgraph is obtained by using the Gabriel graph Combined FACE routing: greedy routing + FACE routing GPSR, GFG,…

4. GPSR F1F1 F2F2 F3F3 F4F4 F5F5 Turn Right or Left ??

5. A Trivial Solution Adding nodes on the face boundaries into the virtual neighbor set VN(u) For a given destination d, the concave node u finds the node v closest to the destination from VN(u) Forwards the packet to v along the shorter direction

6. Problem of the Trivial Solution Size of the virtual neighbor set may be large Some node will never be a concave node Some node is a concave node for destinations in certain angles

7. Objective Determine which nodes maybe concave nodes in a distributed manner Each of those nodes u constructs a virtual neighbor set by sending a short packet For each destination, there is at least one progress node in N(u) ∪ VN(u) The size of the virtual neighbor set is constant

8. Outline Introduction The Virtual Neighbor Set Construction Protocol The ProgessFace Algorithm Performance Evaluation Conclusion

9. Determining which nodes may be concave nodes Assume that u is a concave node for the destination w

10. Stuck Region

11. Construct a Virtual Neighbor Set Zone: The j-th (j>=1) zone of angle ∠ u i uu i+1 denoted by Zone j ( ∠ u i uu i+1 ), is collection of points p, such that D(u, p)>R and j π /3 < ∠ u i up ≦ (j + 1) π/3< ∠ u i uu i+1

12. Construct a Virtual Neighbor Set Which node is a progress node for a given destination w?

13. Construct a Virtual Neighbor Set The coming destination is unpredictable. Any node in the stuck region is in one zone

14. Implementation For each node has at least one stuck region A short packet is forwarded along a face boundary using right-hand rule The closest neighbor in a zone of visited nodes is added Corresponding hop distance is evaluated

15. Collect VN Set Information

16. Outline Introduction The Virtual Neighbor Set Construction Protocol The ProgessFace Algorithm Performance Evaluation Conclusion

17. ProgressFace The concave node u routes a packet toward a node v ∈ VN(u) closest to the destination using the right-hand rule or the left-hand rule according to the evaluated direction until it encounters a node with a progress node in the 1-hop neighborhood.

18. Outline Introduction The Virtual Neighbor Set Construction Protocol The ProgessFace Algorithm Performance Evaluation Conclusion

19. Performance Evaluation Simulation Setup ProgressFace is augmented with GPSR, GFG, GOAFR+, and GPVFR Packet-level simulator Network size: 30 × 30 Network density: 6, 8, ・ ・ ・, 16

20. Perimeter Ratio The square region is 30 The number of voids in the square region is 0 in (A) and 10 in (B) (A) (B)

21. Perimeter Ratio The square region is 10 The number of voids in the square region is 0 in (C) and 3 in (D) (C) (D)

22. Path Stretch The square region is 30 The number of voids in the square region is 0 in (A) and 10 in (B) (A) (B)

23. Maximum Load The square region is 30 The number of voids in the square region is 0 in (A) and 10 in (B) (A) (B)

24. Additional Latency The square region is 30 The number of voids in the square region is 0 in (A) and 10 in (B) (A) (B)

26. Conclusion Virtual neighbor sets are used in FACE routing Hop distance of nodes in the virtual neighbor set along both directions are evaluated Capable of augmenting with combined FACE routing protocols to improve routing efficiency