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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. Outline. Introduction Background and Motivation Proposed scheme: FERMA
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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
Outline • Introduction • Background and Motivation • Proposed scheme: FERMA • Performance Evaluation • Conclusion
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
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
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
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
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
Background and Motivation-Applying Fermat Point concept for SN geocasting
Background and Motivation-Applying Fermat Point concept for SN geocasting
Proposed scheme: FERMA 1.three geographical coordinates with Fermat point 2.two central points of the target regions
Proposed scheme: FERMA Flooding Flooding
Proposed scheme: FERMA • Data packet forwarding Phase • Gradient • All nodes record the previous hop which forwards that interest
Proposed scheme: FERMA • Aggregation • Each target region • Fermat points • Latency of data delivery becomes longer
Simulation • Metrics • Packet overhead • Energy consumption • Performance affected by the number of target regions • Comparisons • Pure greedy forwarding • Flooding
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
Environment-Results Average Number of Interest Packets Average Number of Data Packets
Environment-Results Average Consumed Energy (Joules/Node/Distrinct Query) Average Number of Total Packets
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