1. 1 Cooperation in Multi-Domain Sensor Networks Márk Félegyházi Levente Buttyán Jean-Pierre Hubaux {mark.felegyhazi, jean-pierre.hubaux}@epfl.ch EPFL, Switzerland TERMINODES Project (NCCR-MICS) http://www.terminodes.org buttyan@hit.bme.hu Budapest University of Technology and Economics, Hungary PerSeNS 2005.03.08

2. 2 Multi-domain sensor networks  co-located sensor networks  sensors are compatible  sinks can be either separate or common

3. 3 Non-cooperative game  assumption: paths to the sink exist in both own and common network  the game unfolds in discrete time steps t  lifetime of sensor networks: until the first sensor dies  finite routing game: ends when one subnetwork dies

4. 4 Benefits of cooperation  operators as players  two decisions:  ask (or not) the other player to cooperate  cooperate (or not) if asked  reduce complexity: strategy is pre-defined in the sensors

5. 5 Strategies  success of data gathering: if  moves:  strategy: where: is the gathered number of measurements is the requirement for success  pre-programmed strategy in the sensors  feedback in one bit from the sink (successful or not) DD - don't ask/drop DF - don't ask/forward AD - ask/drop AF - ask/forward successXX next moveXX

6. 6 Utilities  gain, g i (t): if the step was successful, then g i (t) = G i otherwise g i (t) = 0  cost, c i (t): sum of the transmission cost of all sensors (c unit ~ d α )  payoff,  utility: where: T is the lifetime of the sensor network

7. 7 Simulation parameters Number of sensors per domain10 - 50 (25) Distribution of the sensorsuniformly random Area size40 x 20 m Reception energy (R)100 units Transmission energy (Tr)Tr ~ d α units Path loss exponent2 – 5 (4) Success requirement (SR i )1.0 (all sensors have to report) Position of the sinks (separate sinks)[10,10] and [30,10] Position of the sinks (common sinks)[20,10] Route selectionMinimum energy path

8. 8 Best strategies  Three types:  Cooperative: (AF, AF)  Defective: (DD, DD)  Other: for example (AF, DD)

9. 9 Simulations: Separate sinks

10. 10 Simulations: Common sinks

11. 11 Simulations: Path loss exponent

12. 12 Conclusion Cooperation is beneficial, because it can increase the lifetime of sensor networks.  For separate sinks, operators can use the sinks of each other  For common sinks, cooperation is beneficial:  if sensor networks are sparse – overhearing of packets is less significant  if path loss is high - transmission is expensive