1. Hello: A Generic Flexible Protocol for Neighbor Discovery Wei Sun, Zheng Yang, Keyu Wang and Yunhao Liu CSE, Hong Kong University of Science and Technology School of Software and TNList, Tsinghua University Gaoyang Guan

2. Motivation Neighbor discovery is crucial Better trade-off between duty cycle and discovery latency

3. Challenges Existing protocols’ parameters are highly restricted Reduce or take advantage of redundant discovery Existing protocols cannot adjust well to application demands

4. Contributions A neighbor discovery protocol that exhibits the highest degree of freedom. An optimality analysis under a generic framework. A flexible solution to applications dynamics. Extensive evaluation through simulation and real world experiments.

5. Design A. Schedule Design

6. Design A. Schedule Design Possible solutions Stay active in the first slots Our design expand the period to cn slots wakes up at the first slot of each cycle wakes up at the consecutive slots indexed from 1 to c/2 in the first cycle

7. Design B. Symmetric Discovery Latency Lemma 1. The worst-case discovery latency Ls for Hello under symmetric duty cycles with parameter pair (c; n) is cn slots.

8. Design

9. D. A Generic Framework

10. Design E. Optimality Analysis 1) Optimum for symmetric duty cycles: Searchlight

11. Design 2) Optimum for asymmetric duty cycles: This result well explains why Disco performs best under asymmetric duty cycles

12. Design 3) A compromise: worst-case latency U-Connect

13. Design G. Redundancy 1) Redundancy from slot non-alignment beaconing at both the beginning and the end of an active slot leads to two discovery opportunities 2) Redundancy from repetitive patrols each patrol is put at a randomly selected cycle (row) but at the same relative position (column) within the cycle

14. Evaluation

19. IMPLEMENTATION

20. Q&A