The distributed and the Grid Computing architectures for the simulation of massively populated wireless systems have recently been considered of interest, mainly for cost reasons. Solutions for generalized proximity detection for mobile objects is a relevant problem, with a big impact on the design and the implementation of parallel and distributed simulations of wireless mobile systems. In this paper, a set of solutions based on tailored data structures, new techniques and enhancements of the existing algorithms for generalized proximity detection are proposed and analyzed, to increase the efficiency of distributed simulations. The paper includes the analysis of computation complexity of the proposed solutions and the performance evaluation of a testbed distributed simulation of ad hoc network models. Recent works have shown that the performance of distributed simulation of dynamic complex systems could benefit from a runtime migration mechanism of model entities, which reduces the communication overheads. Such migration mechanisms may interfere with the generalized proximity detection implementations. The analysis performed in this paper illustrates the effects of many possible compositions of the proposed solutions, in a real testbed simulation framework.

1. Gabriele D’Angelo Lorenzo Donatiello Luciano Bononi Michele Bracuto Department of Computer Science University of Bologna Torremolinos, 03/10/2006 Proximity Detection in Distributed Simulation of Wireless Mobile Systems

10. Simulated Mobile Hosts (SMHs) migration Wireless ad hoc network scenario: (evaluating migration of SMH x) X’s “transmission-event” must be notified to the 4 model entities executed over B After X’s migration, X’s “transmission-event” must be notified to one model entity executed over A A B network delay Physical Execution Units for the simulation model entities of SMHs executed over PEUs A and B Host X executed over PEU A “transmission-event” A B network delay Physical Execution Units for the simulation model entities of SMHs executed over PEUs A and B Same scenario after migration of X from A to B X X X SMH = Simulated Mobile Host PEU = Physical Execution Unit

11. The visual effect of the migration based mechanism Migration OFF Migration ON

15. Simulation results: proximity detection

16. Proximity detection: grid-based

17. Proximity detection: all-pairs with caching ON/OFF

18. Proximity detection: enhanced all-pairs

19. Proximity detection: all-pairs with migration and caching ON/OFF

20. Proximity detection: migration ON/OFF

22. Gabriele D’Angelo Lorenzo Donatiello Luciano Bononi Michele Bracuto Department of Computer Science University of Bologna Torremolinos, 03/10/2006 Proximity Detection in Distributed Simulation of Wireless Mobile Systems