1. Toward a Packet Duplication Control for Opportunistic Routing in WSNs Georgios Z. Papadopoulos, Julien Beaudaux, Antoine Gallais, Periklis Chatzimisios, and Thomas Noel (University of Strasbourg - France, Norwegian University of Science and Technology – Norway, and Alexander TEI of Thessaloniki - Greece) In Proceedings of the IEEE Globecom, London, Austin, TX, USA, December 2014 Nov. 24, 2015 Minwoo Joo (mwjoo@korea.ac.kr)

2. Outline Introduction Problem Statement & Proposed Mechanism Performance Evaluation Conclusions and Future Work 2

3. Introduction Opportunistic Routing Packets are sent opportunistically (i.e. anycast) A data packet is transmitted to the first potential forwarder acknowledging the corresponding message To save energy, low power listening MAC mechanisms are adopted where preamble are transmitted (and acknowledged) prior to any data communication By increasing the number of potential forwarders, several neighbors lead to faster (yet multiple) preamble ACKs Thus, it allows for improved throughput, reduced end-to-end delays and more balanced energy consumption between nodes 3

4. Introduction Redundant Packet Forwarding A single packet could be received by multiple neighbors due to their homogenous configurations e.g., duty-cycle This leads to several distinct messages, recursively propagated at each hop, and eventually to packet duplication at the sink Increased traffic and channel occupancy over the entire network 4

5. Introduction Potential Deafness It introduces heterogeneity among nodes to reduce the probability of having multiple receivers for a single packet Nodes dynamically regulate their configurations in localized manner without endangering network disconnection Advantages Improved network performance Reduced energy consumption 5

6. Problem Statement & Proposed Mechanism Problem Statement: Packet Duplication In WSNs relying on opportunistic routing, two factors need to be fulfilled for a single data packet to be received by several neighbors Two or more nodes have to sample their radio channel while the packet is being transmitted These nodes have to successfully catch the preamble and acknowledge it 6

7. Problem Statement & Proposed Mechanism Problem Statement: Packet Duplication (Cont’d) This problem can be formalized by adapting the birthday paradox The probability of any other potential forwarder to sample the medium at the same time slot is given as follows 7

8. Problem Statement & Proposed Mechanism 8

9. Proposed Mechanism: Potential Deafness This paper introduce the potentiality of deafness in WSN The key idea is to adapt a node’s wakeup interval to the local number of potential forwarders It is assumed that a gradient protocol is used which generates a routing tree rooted at the sink Thus, each node can obtain the local number of potential forwarders by overhearing messages broadcasted during the construction of the routing tree 9

10. Problem Statement & Proposed Mechanism Proposed Mechanism: Potential Deafness (Cont’d) The number of potential forwarders can be used in accordance with application-level performance parameters (e.g., QoS, lifetime, etc.) to affect each node in the network with a specific wake-up interval A multi-objective optimization problem (MOP) is formulated based on these parameters The solution to this MOP represents the best-suited MAC parameters a node can be configured with to fulfill all application requirements As a result, heterogeneous configurations among the nodes lead to potential deafness The applicative parameters may change over time for fairness 10

11. Performance Evaluation Experimental Setup Over the Strasbourg platform of the FIT IoT-LAB testbed 3D grid of 240 fixed nodes TI CC11011 radio chipset and MSP430 micro-controller Implementation with X-MAC protocol Applicative requirement as a maximal duplication probability of 60% 11

12. Performance Evaluation Packet Duplication 12

13. Performance Evaluation Reliability, Delay, and Energy Consumption 13

14. Conclusions and Future Work This paper examines to what extent the auto-adaptive mechanism can mitigate packet duplication in opportunistic routing The proposed mechanism is based on local configuration at each node The experimental results show that the adaptive mechanism achieves better performance in terms of delay, PRR, as well as energy consumption The ongoing work consists of further exploring this lead in mobile sensors 14

15. Thank You. Q & A 15