Lyon, June 26th 2006 ICPS'06: IEEE International Conference on Pervasive Services 2006 Routing and Localization Services in Self-Organizing Wireless Ad-Hoc and Sensor Networks Using Virtual Coordinates Gianluca Moro*, Gabriele Monti*, Aris M. Ouksel^ *DEIS, University of Bologna {gmoro, ^University of Illinois, Chicago (USA)

Lyon, June 26th 2006ICPS'06: IEEE International Conference on Pervasive Services 2006 Summary Introduction to Ad-hoc and sensor networks and to existing routing solutions Description of W-Grid features and characteristics Experimental results Future works

Lyon, June 26th 2006ICPS'06: IEEE International Conference on Pervasive Services 2006 Recent advances in ICT have led to the rapid development of small, powerful, multi-function devices equipped with interfaces (Bluetooth, Wi-Fi and Wi-Max) Realization of Ad-hoc and sensor networks has become possible Devices can communicate without the need of a fixed pre- configured infrastructure Devices can communicate without the need of a fixed pre- configured infrastructure Connectivity is supported by multi-hop transmissions Connectivity is supported by multi-hop transmissions Devices act both as users and as signal repeaters at the same time Devices act both as users and as signal repeaters at the same time Introduction

Lyon, June 26th 2006ICPS'06: IEEE International Conference on Pervasive Services 2006 Related works Routing protocols for ad-hoc networks can be classified into three main categories Table-driven (proactive) Routing information about every possible destination is stored at each device Routing information about every possible destination is stored at each device Changes in network topology trigger propagating updates in order to maintain a Consistent view (heavy bandwidth utilization) Changes in network topology trigger propagating updates in order to maintain a Consistent view (heavy bandwidth utilization) On-Demand (or Reactive) A path discovery mechanism is initiated whenever destination is not known A path discovery mechanism is initiated whenever destination is not known Path discovery requires a form of message flooding which causes latency and network overhead Path discovery requires a form of message flooding which causes latency and network overhead Geographic routing protocols. Packets are forwarded trying to reduce as much as possible the physical distance to the destination Packets are forwarded trying to reduce as much as possible the physical distance to the destination Good scalability (no flooding is used) Good scalability (no flooding is used) Dead-ends may occur under low density environment or in case of obstacles Dead-ends may occur under low density environment or in case of obstacles Devices must be location aware (requires GPS or another positioning system) Devices must be location aware (requires GPS or another positioning system) Ad-Hoc routing protocols Table-driven protocols (proactive) On-demand protocols (reactive) DSDV CGSR WRPAODVDSRLMRABR SSRTORA Geographic protocols GPSR

Lyon, June 26th 2006ICPS'06: IEEE International Conference on Pervasive Services 2006 W-Grid: Features and characteristics Features: Allows efficient routing and data management without global knowledge about network and without central coordination Participants know only about their direct neighbors Participants know only about their direct neighbors Currently we work with networks of static devices Characteristics: Devices are mapped into nodes of a binary tree Each device is assigned virtual coordinate(s) Virtual coordinates correspond to the binary strings that identify nodes of the binary tree Coordinates represent portions of the data space

Lyon, June 26th 2006ICPS'06: IEEE International Conference on Pervasive Services 2006 W-Grid: Coordinates generation Node n 1 turns on and elects itself as root of a new W-Grid network n1n1 * n1n1 Node n 2 joins the network, a new coordinate is needed n2n2 *0*1 n1n1 n3n3 *0 n3n3 n1n1 n2n2 Each joining node gets a coordinate as previously described * *01*00 Node n 1 creates a new coordinate (split) * by concatenating a bit to it n 2 is given coordinate *1 Node n 1 keeps the coordinate *0 *1 Coordinate * cannot be split anymore, therefore *0 is split *01 *00 n 3 is given *01 Node n 1 keeps the coordinate *00

Lyon, June 26th 2006ICPS'06: IEEE International Conference on Pervasive Services 2006 W-Grid: Total order relationship We can define a total order relationship among coordinates (and consequently among nodes) By assigning more than one coordinate to each node we reduce effects of mapping a multi- dimensional space into a one-dimensional space Es < 1110

Lyon, June 26th 2006ICPS'06: IEEE International Conference on Pervasive Services 2006 W-Grid: Network example n 1 * *001 * *0101 *0000 n 2 *1100 * * *11100 *11010 * * n 13 * * n 12 * * * * n 11 * * * * n 18 * * * * n 20 * * * * n 19 * * * * * n 8 * * * n 14 * * * n 6 * * * * * n 5 *11011 *0001 *01101 * n 4 *01 * *01100 * * n 7 *01000 * * * n 15 * * * n 16 * * * n 17 * n 10 * * * * * n 9 * *11101 * * * n 3 * * * *100111

Lyon, June 26th 2006ICPS'06: IEEE International Conference on Pervasive Services 2006 W-Grid: Routing Based on the concept of distance between coordinates d(*0011,*011) = 5 Given a destination coordinate c d, at each step we choose the neighbor which mostly reduces the distance to c d For each coordinate, a number of coordinates have the same distance, for example: d(*01,*111) = 5; d(*01,*00011) = 5; d(*01,* ) = 5 In general, given a distance d, this number is: where Δ= d – (l – pref) where Δ= d – (l – pref)

Lyon, June 26th 2006ICPS'06: IEEE International Conference on Pervasive Services 2006 W-Grid and GPSR: Routing example n 1 * *001 * *0101 *0000 n 2 *1100 * * *11100 *11010 * * n 13 * * n 12 * * * * n 11 * * * * n 18 * * * * n 20 * * * * n 19 * * * * * n 8 * * * n 14 * * * n 6 * * * * * n 5 *11011 *0001 *01101 * n 4 *01 * *01100 * * n 7 *01000 * * * n 15 * * * n 16 * * * n 17 * n 10 * * * * * n 9 * *11101 * * * n 3 * * * *100111

Lyon, June 26th 2006ICPS'06: IEEE International Conference on Pervasive Services 2006 W-Grid: Data management Virtual coordinates implicitly generate a distributed database n 1 *01 *1 * *01 *00 *11 *10 *0 n 4 *11n 2 *10n 3 *00 n 1 * n 2 *1 n 1 *0 *010 Regions that have been split, they do not manage any data but they may be used for routing Regions that can manage data, they are also used for routing

Lyon, June 26th 2006ICPS'06: IEEE International Conference on Pervasive Services 2006 W-Grid: Location service Corresponds to a data management where data are devices virtual coordinates Each device has a unique identifier which is used as key for each node search When a device joins the network it insert in the database information about its virtual coordinates We define as locator the device which is aware of coordinates of another device A device that need to contact another device n ID Searches the database for key = ID Searches the database for key = ID Once the locator has been reached the message will be routed to n ID Once the locator has been reached the message will be routed to n ID mittente locator destinatario

Lyon, June 26th 2006ICPS'06: IEEE International Conference on Pervasive Services 2006 Experimental results Routing performances of W-Grid have been compared to GPSR routing algorithm

Lyon, June 26th 2006ICPS'06: IEEE International Conference on Pervasive Services 2006 Future works In order to improve routing efficiency we are currently testing some new solutions: Coordinate spaces replication Generation of several coordinate spaces at the same time Generation of several coordinate spaces at the same time Nodes learning Introducing an efficient and scalable path learning strategy at nodes Introducing an efficient and scalable path learning strategy at nodes We are also starting theoretical analysis in order to evaluate the effects of nodes mobility

Lyon, June 26th 2006 ICPS'06: IEEE International Conference on Pervasive Services 2006 Thank you!