1. The “New Network Node” Algorithm Brought to you by: Brian Wolf(Researcher) Harlan Russell (Advisor) Joe Hammond (Advisor Emeritus) Vivek Mehta(Graduate Student) Praveen Appani(Graduate Student)

2. Outline Mobile, Distributed, Wireless Networks Time Division Multiple Access Algorithm for adding a New Node How well does this algorithm work? Conclusions

3. Mobile, Distributed, Wireless Network ? What Is A All network nodes are mobile No permanent network infrastructure No centralized control Variable terrain and propagation conditions Network topology can be irregular RegularIrregular

4. Time Division Multiple Access (TDMA) Time is divided into fixed-length time slots In one time slot, a node may transmit or receive 1 message Collisions prevent a node from receiving a message

5. Collision Type 1: two neighbors transmit at the same time Collision Type 2: one node has two neighbors transmit at the same time TDMA – Collision Types

6. Slot Assignments 12345678 1 2 3 4 5 12345678 1 2 3 4 5 1 2 5 3 4 1 2 3 4 5 Slot # (examples) Fully Connected Network Linear Network

7. Mobility Can Change A Network 1 2 3 4 5 1 2 3 4 5 1 2 3 4 5 R 1. Deleted Link 2. Added Link 3. New Node

8. The New Node Algorithm When a New Node powers up, it: Listens to network to find out who neighbors are Announces its presence by “shouting” Waits while neighbors quiet down their neighbors Exchanges transmission scheduling information Modifies schedule as needed to improve efficiency

9. How Is the Algorithm Tested? Goals for New Node Algorithm: 1)Convergence - completion time 2) Success - new node knows all about neighbors - neighbors know all about new node Tested by: 1) Randomly generated networks 2) Variable Density (avg. # of neighbors)

10. How Does the Algorithm Work? (1)

11. How Does the Algorithm Work? (2) Soft failure: Node has all neighbors, but information about cycle size is wrong or 2 neighbors are not deferring Hard failure: Node failed to detect all neighbors

12. Conclusions  Algorithm takes longer to complete in dense networks  Algorithm is more reliable in dense networks  Chance of having undetected neighbors (hard failure) is small  Complete success (no failures) is much harder to achieve for some network densities than others

13. Future Work Finish the algorithm Test the algorithm more extensively Develop alternative algorithms Improve simulation software