1. FERMA: An Efficient Geocasting Protocol for Wireless Sensor Networks with Multiple Target Regions Young-Mi Song, Sung-Hee Lee and Young- Bae Ko Ajou University Lecture Notes in Computer Science 2005

2. Outline  Introduction  Background and Motivation  Proposed scheme: FERMA  Performance Evaluation  Conclusion

3. Introduction  In WSN, a query (interest) is used to have sensor nodes collect data and return these sensing data Flooding mechanism  Increases network traffic and leads inefficient energy consumption Geographical propagation  One single target region

4. Introduction  Objective Efficiently deliver interest messages to multiple target regions  Latency  Bandwidth consumption  Method Send interest just once at the sink node  Suitable shared path  Multiple packet transmissions toward different target regions Data aggregation  Fermat Point  Entrance nodes

5. Background and Motivation  What is the point such that the sum of its distances from the vertices of a triangle is a minimum? Fermat point

6. Background and Motivation- Fermat point  Fermat Point is the point such that the sum of its distances from the vertices of a triangle is a minimum

7. Background and Motivation- Fermat point  One of the internal angles of ΔABC is 120° or more Fail to construct the Fermat Point Fermat Point is drawn outside of the triangle

8. Background and Motivation- Applying Fermat Point concept for SN geocasting

10. Proposed scheme: FERMA 1.three geographical coordinates with Fermat point 2.two central points of the target regions

11. Proposed scheme: FERMA Flooding

12. Proposed scheme: FERMA

13.  Data packet forwarding Phase Gradient  All nodes record the previous hop which forwards that interest

14. Proposed scheme: FERMA  Aggregation Each target region Fermat points  Latency of data delivery becomes longer

15. Simulation  Metrics Packet overhead Energy consumption Performance affected by the number of target regions  Comparisons Pure greedy forwarding Flooding

16. Simulation- Environment  NS-2  100 nodes  200m*200m  Sink is at (0,0)  Target region: 1 to 5  Interest packet: 36 bytes  Data packet: 64 bytes

17. Environment-Results Average Number of Interest PacketsAverage Number of Data Packets

18. Environment-Results Average Number of Total Packets Average Consumed Energy (Joules/Node/Distrinct Query)

19. Conclusion  Efficient interest forwarding in the environment of multiple target regions Suitable shared path among multiple target regions  Theorem of Fermat Point Two-level data aggregation scheme  Ongoing work Avoid the obstacle