Hybrid Position Based Routing Algorithms for 3D Mobile Ad Hoc Networks

1. Hybrid Position Based Routing Algorithms for 3D Mobile Ad Hoc Networks Authors: Song Liu, Thomas Fevens and Alaa Eddien Abdallah Presented by: Brandon Hetman

2. Overview • Problem Addressed • Background & Previous Work • Hybrid Routing Algorithm • Loop Detection • Mobility Concerns • Questions

3. Problem Addressed • Current MANET research is focused on 2D networks • This is rare in practice • 2D assumptions and concepts to not extend well to 3D

4. Background & Previous Work

5. Evaluation Metrics • Delivery Rate • Hop Stretch: Hops used/ Number of Hops in the Shortest Path

6. 2D GREEDY Routing • Next hop is greedily chosen to maximize progress toward destination • Falls back to perimeter FACE routing • High hop stretch, guaranteed delivery

7. Projective FACE • Create two orthogonal planes intersecting along the line between source and destination • FACE route along the first plane, switching to the second upon failure Improved delivery rate, but significantly increased hop stretch

8. Adaptive Least-Squares Projective Routing • Uses a Least Squares Projection plane of the source, two hop neighbors, and destination nodes • Least Squares minimization of node distance to the plane • Route along this plane for a number of hops then recompute the plane • Switch between N such planes to disrupt routing loops 100% simulated delivery rate, increased hop stretch

9. Coordinate FACE • Attempt to Route in plane projections successively: • xy plane • yz plane • zx plane 95% delivery rate, hop stretch greater than 10

10. Distance Routing Effect Algorithm for Mobility & Location Aided Routing • Limited flooding algorithms • Nodes unlikely to be on a shortest path don't forward • Limiting Strategies • DREAM: A cone with apex at the source, centered about the destination, with the minimum angle to contain the expected region • LAR: Minimum sized cube with the source at one corner and the expected region at the opposite one

11. New Hybrid Routing Algorithm

12. Two Strategies • GFG: • Use 3D GREEDY routing until no progress can be made • Switch to ALSP FACE to make progress • Switch back to 3D GREEDY routing • Project the 3D network onto an LSP plane • Use 2D GREEDY routing in this plane falling back to ALSP FACE

13. ALSP GFG Algorithm • GREEDY route along the first order ALSP plane • Upon reaching a local minimum ℓ use ALSP FACE until the current node is closer to the destination than ℓ • Resume GREEDY routing • Repeat until the destination is reached

14. Loop Detection • Visited Edges Array: Store the last 𝓜 nodes. If the current node is in the array switch to the ALSP plane • Restart node: Before restarting backtrack to the node with the highest degree to minimize the probability of immediately encountering a local minimum

15. Loop Detection Continued • Switch Node Array: Store the last 𝓚 nodes at which a switch to ALSP was needed. If a second switch is needed at one of these nodes backtrack and restart using the next ALSP plane.

16. Mobility Concerns • Isolated Nodes: nodes with no neighbors • hold all packets until a neighbor is found • Destination Moved: • Node nearest destination's expected position floods the packet • Only routers that have seen the destination rebroadcast

17. Questions?