1. Kommunikationssysteme FORSCHUNGSINSTITUT FÜR KOMMUNIKATION, INFORMATIONSVERARBEITUNG UND ERGONOMIE FGAN 0 Relay Placement for Ad-hoc Networks in Crisis and Emergency Scenarios RTO IST-086 Symposium on C3I for Crisis, Emergency and Consequence Management Bucharest, Romania 11. May 2009 Thorsten Aurisch, Jens Tölle

2. Kommunikationssysteme FORSCHUNGSINSTITUT FÜR KOMMUNIKATION, INFORMATIONSVERARBEITUNG UND ERGONOMIE FGAN 1 Overview Challenge, Basic Scenario Ad-hoc Network Properties Indoor Communication Challenges Relay Placement Concepts Demonstrator Test Scenarios Results Improvements Conclusions Challenge, Basic Scenario Ad-hoc Network Properties Indoor Communication Challenges Relay Placement Concepts Demonstrator Test Scenarios Results Improvements Conclusions

3. Kommunikationssysteme FORSCHUNGSINSTITUT FÜR KOMMUNIKATION, INFORMATIONSVERARBEITUNG UND ERGONOMIE FGAN 2 The Challenge – Basic Scenario Emergency Responder/ Unites Crisis/Emergency Situation Incident Command Center/ Command Post Command and Control Feedback, Sensor Data, ACKs, Blueforce Tracking,… Crisis Area Reliable two-way communication needed!

4. Kommunikationssysteme FORSCHUNGSINSTITUT FÜR KOMMUNIKATION, INFORMATIONSVERARBEITUNG UND ERGONOMIE FGAN 3 crisis area mobile base station units incident command center crisis area ad-hoc network incident command center units Communication Structures Base stations: GSM, UMTS, PMR - Single Hop - Infrastr. dependant Mobile Ad-hoc networks - Multi Hop - not Infrastr. dependant

5. Kommunikationssysteme FORSCHUNGSINSTITUT FÜR KOMMUNIKATION, INFORMATIONSVERARBEITUNG UND ERGONOMIE FGAN 4 Ad-hoc Network Advantages No infrastructure needed No installation of temporary base station needed Units can start communicating directly upon arrival Additional units enhance density of the ad-hoc network: - multiple routes - increased robustness

6. Kommunikationssysteme FORSCHUNGSINSTITUT FÜR KOMMUNIKATION, INFORMATIONSVERARBEITUNG UND ERGONOMIE FGAN 5 command post interruption Ad-hoc Network Challenges Sometimes difficult radio propagation properties, especially in buildings Risk of communication network partitioning Rapid deployment needed in previously unknown terrain

7. Kommunikationssysteme FORSCHUNGSINSTITUT FÜR KOMMUNIKATION, INFORMATIONSVERARBEITUNG UND ERGONOMIE FGAN 6 interruption t1t1 t2t2 Indoor Challenge signal strength strong weak Sudden decrease of signal strength (corners, concrete walls, metal doors) may cause network disruption

8. Kommunikationssysteme FORSCHUNGSINSTITUT FÜR KOMMUNIKATION, INFORMATIONSVERARBEITUNG UND ERGONOMIE FGAN 7 relay node Indoor Challenge: Solution Relay Placement Signal strength is monitored, decreasing signal strength triggers alarm, unit activates and deploys relay node.

9. Kommunikationssysteme FORSCHUNGSINSTITUT FÜR KOMMUNIKATION, INFORMATIONSVERARBEITUNG UND ERGONOMIE FGAN 8 Relay Placement: Known Concepts Relay placement approaches are used in different areas: Sensor networks: Usage of relay nodes to improve connectivity Energy efficiency by decreasing transmission power Autonomous multi-robots: Robots can actively move to positions to (re)gain connectivity Tracking by means of pre-installed relay nodes: Limited range of application Sometimes used: Optimization algorithms with unrealistic assumptions Needed: Pragmatic and robust solution

10. Kommunikationssysteme FORSCHUNGSINSTITUT FÜR KOMMUNIKATION, INFORMATIONSVERARBEITUNG UND ERGONOMIE FGAN 9 The RelayP Concept Assumptions Relay nodes are simple, cheap, and available Usage of COTS components (e.g. IEEE 802.11 b/g radios) Incident environment and current situation unknown Exisiting communication infrastructure failed or overloaded

11. Kommunikationssysteme FORSCHUNGSINSTITUT FÜR KOMMUNIKATION, INFORMATIONSVERARBEITUNG UND ERGONOMIE FGAN 10 The RelayP Concept II Demonstrator development: - Decision to drop a node depends on quality of existing link - Used metric: Received Signal Strength (RSS) - Two different methods for RSS calculation 1. Determine RSS by radiotap header analysis of last N beacons - Beacons are periodically sent by all devices - Approach does not generate additional traffic 2. Usage of channel probing signals - Send PROBE_MSG every seconds - Deployed relay node or incident command centre replies with PROBE_ACK - Calculate moving average of last N messages

12. Kommunikationssysteme FORSCHUNGSINSTITUT FÜR KOMMUNIKATION, INFORMATIONSVERARBEITUNG UND ERGONOMIE FGAN 11 Test Scenario 1/3 Demonstrator test cases: (Notebooks, Linux 2.6.26, IEEE802.11b) Outcome of tests depends on building, materials,… Test scenario 1: Communication in a straight line

13. Kommunikationssysteme FORSCHUNGSINSTITUT FÜR KOMMUNIKATION, INFORMATIONSVERARBEITUNG UND ERGONOMIE FGAN 12 Test Scenario 2/3 Test scenario 2: Communication moving around a corner

14. Kommunikationssysteme FORSCHUNGSINSTITUT FÜR KOMMUNIKATION, INFORMATIONSVERARBEITUNG UND ERGONOMIE FGAN 13 Test Scenario 3/3 Test scenario 3: Communication entering a room

15. Kommunikationssysteme FORSCHUNGSINSTITUT FÜR KOMMUNIKATION, INFORMATIONSVERARBEITUNG UND ERGONOMIE FGAN 14 Signal Strength vs. Packet Loss Estimation of threshold -96 dbm radio reception threshold -90 dbm as relay drop threshold?

16. Kommunikationssysteme FORSCHUNGSINSTITUT FÜR KOMMUNIKATION, INFORMATIONSVERARBEITUNG UND ERGONOMIE FGAN 15 Attenuation by moving persons Estimation of Deviation Result: Standard deviation of 1.5 dbm -87 dbm relay drop threshold

17. Kommunikationssysteme FORSCHUNGSINSTITUT FÜR KOMMUNIKATION, INFORMATIONSVERARBEITUNG UND ERGONOMIE FGAN 16 Distance Measurements Distance [m]

18. Kommunikationssysteme FORSCHUNGSINSTITUT FÜR KOMMUNIKATION, INFORMATIONSVERARBEITUNG UND ERGONOMIE FGAN 17 Drawbacks and Potential Improvements Organize common movement of response units Consider small-scale fluctuations when moving in groups by combined evaluation of metric Consider network partitioning in case of group movements

19. Kommunikationssysteme FORSCHUNGSINSTITUT FÜR KOMMUNIKATION, INFORMATIONSVERARBEITUNG UND ERGONOMIE FGAN 18 Conclusions Relay placement approach for crisis scenarios Fast and pragmatic solution No optimal solution, but sufficiently good heuristic No preparation time needed Does not constrain emergency responders/units

20. Kommunikationssysteme FORSCHUNGSINSTITUT FÜR KOMMUNIKATION, INFORMATIONSVERARBEITUNG UND ERGONOMIE FGAN 19 … Thank you very much for your Attention! Questions? Jens Tölle toelle@fgan.de Telephone: +49 228 9435 513 Fax: +49 228 9435 685