SOWER: Self-Organizing Wireless Network for Messaging

1. SOWER: Self-Organizing Wireless Network for Messaging Srdjan Čapkun Márk Félegyházi Jean-Pierre Hubaux {mark.felegyhazi, srdan.capkun, jean-pierre.hubaux}@epfl.ch Laboratory for computer Communications and Applications, Swiss Federal Institute of Technology (EPFL) – Lausanne, Switzerland TERMINODES Project (NCCR-MICS) http://www.terminodes.org

2. SOWER: Self-Organizing Wireless Network for Messaging • Intro to ad hoc networks • Motivation • System approach • Connectivity investigations: measurement and simulations • Conclusion and future work

3. Ad Hoc Networks • self-organizing network – no infrastructure • each networking service is provided by the nodes themselves • devices powered by a battery – energy constraints

4. Motivation – Cellular Networks • Short Messaging (SMS): • a simple way of communication → popular • does not require high bandwidth • delay tolerant (in the order of tens of seconds / minutes) • BUT: • price of SMS is extremely high • infrastructure of base stations is complex and expensive: deployment and maintenance costs • users have no alternative • Future vision: • self-organizing and robust short messaging • new services / applications

5. h A Self-Organizing Wireless Messaging Network (SOWER) Each user owns: home device mobile device m • Home devices are: • power plugged – always on • static devices • same radio as mobiles Home devices form a wireless backbone for message transmission

6. Connectivity measurements (1/2) Measurement campaign: 500m * 500m in Lausanne center • Parameters: • laptops with 801.11b wireless _cards • random measurement points • 1 Mbit/s channel capacity • 100 mW transmission power

7. Connectivity measurements (2/2) Main observation: With the device density equal to 220 devices/km2, we can provide a messaging network in a small city with a high coverage.

8. Parameter Scenario street width building width Metropolis 80 m 40 m 50 m Small city 20 m 13.25 m 35 m Suburban Connectivity and coverage – simulation parameters Investigate the connected component of home devices Home devices uniformly placed in the buildings.

9. Connectivity and coverage – simulations in 2D Coverage: The proportion of the covered area of the largest connected component Connectivity: The proportion of the largest connected component

10. Connectivity – simulations in 3D Skyscrapers Small buildings – 5 floors

11. Penetration requirements Scenario ultra-modern (Manhattan) modern (Berlin) historic (Rome) small (Berkeley) Population density (persons/km2) 25850 12500 8177 2260 Required device density (devices/km2) 5000 3000 700 380 Required market penetration (simulation for 100mW) 0.193 0.24 0.086 0.168 Required market penetration (calculated for 1W, α=5) 0.06 0.05 0.02 0.04

12. Conclusion SOWER: All-wireless messaging network in cities • self-organizing messaging network • city-wide connectivity can be achieved with low market penetration • capacity is sufficient to support messaging

13. Additional technical issues • Deployment of the network • using existing infrastructure (dual-mode devices) • higher transmission power (1 W in the US) • Access to the infrastructure • cellular networks • high-speed Internet connections • Capacity • links have higher transmission rate (up to 54 Mbit/s nowadays) • Addressing + Routing • Security • end-to-end security • trust issues • cooperation • Pricing • secure micropayment mechanism

14. Future work • extensive measurements in different city scenarios • routing issues – include mobile devices in the packet forwarding • charging and security issues • implementation • More info: • web >> http://lcawww.epfl.ch/felegyhazi/ • email >> mark.felegyhazi@epfl.ch