Information Assurance in Sensor Networks

1
Information Assurance in Sensor Networks

• B. Deb, S. Bhatnagar, and B. Nath
• Rutgers University
• WSNA 2003

2
Introduction

• Not all information is equal
• Classification into Assurance Levels
• Reliability and delay targets
• Higher importance higher targets
• Current approaches are boolean
• Penalty in energy or assurance
• Delivery effort proportional to criticality

3
Problem Scenario

• Delivery of information with reliability r
• Key assumptions
• Symmetric links
• Single sink
• Hop distance (h) to sink known
• Ability to classify information
• Ability to cache packets
• Methods to examine
• Unicast (HHR and HHRA)
• Broadcast (HHB and HHBA)

4
Hop-by-Hop Reliability (HHR)

• Source sends packet copies to one next hop
• Hop reliability
• gt 1 transmission needed if
• Epackets sent NHHR Eoverhead OHHR

5
HHR Acks (HHRA)

• Assume acks always received
• Source sends only if last packet lost
• Never send more than NHHR packets

6
Comparison Plots
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Broadcast Extension

• Number of packets sent decreases
• Want only one receiver to forward packet
• Done probabilistically

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Broadcast Extension (2)

• Overhead for HHB and HHBA
• Under assumption that ri r1/h
• Optimal allocation for ri can be found for HBBA
• r1 r, ri1 for all other i gt1

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Scheme Comparisons
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Scheme Comparisons
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Conclusions

• Optimal link reliabilities independent of network
• Broadcast medium reduces overhead significantly
• Ack-based schemes should be used if possible
• Future work
• Weaken assumptions
• Vary MAC to introduce collisions
• Simulation/implementation verification