WSN Simulation Template for OMNeT++

1. WSN Simulation Templatefor OMNeT++ Stefan Dulman s.o.dulman@utwente.nl

2. Presentation Overview • OMNeT++ Introduction • Sensor Network Template • Implementation Example • Discussion and future work

3. OMNeT++ Introduction

4. OMNeT++ Features • Simulator designed for fixed, wired, distributed systems (such as: computer networks, multiprocessor systems…) • Discrete time simulator • It is compatible with: DOS, UNIX, WINDOWS (uses C++ and Tcl/Tk) • Several graphical interfaces allows easy debugging and variables inspection • Offers support for parallel execution

5. OMNeT++ Features (2) • Simulated objects are represented by modules • Modules can be simple or composed (depth of module nesting is not limited) • Modules communicate by messages (sent directly or via gates) • One module description consists of: • Interface description (.NED file) • Behavior description (C++ class) • Modules, gates and links can be created: • Statically - at the beginning of the simulation (NED file) • Dynamically – during the simulation

6. OMNeT++ Features (3) • Support is offered for: • Recording data vectors and scalars in output files • Random numbers (also from several distributions) with different starting seeds • Tracing and debugging aids (displaying info about the module’s activity, snapshots, breakpoints) • Simulations are easy to configure using .ini file • Batch execution of the same simulation for different parameters is also included

7. OMNeT++ Features (4) • What is missing or not working as wanted: • Mobile entities and wireless communication between them are not included • Static data types not allowed • For storing data needed by all the modules a central manager has to be created • Communication with this entity goes by messages (slow!) • Using pointers to it is not always good idea (parallel execution) • Execution goes very slow with the increase of the number of messages and when using parameters • Very slow 2D graphical interface made in Tk

8. Sensor Network Template

9. Template Description • What is it: • A fully working project consisting of a network of mobile nodes that can communicate by wireless means. The user has only to implement the wanted algorithm, with no concern on how these issues are handled. • All the parameters of the network can be changed without any need of rewriting any code • Offers (a lot of) easy to use macros for accessing the main functionalities

10. Template Description (2) • Characteristics: • Implements mobility (Random Way Point alg.) • Wireless communication • Simulated by dynamically connecting modules within transmission range • Unidirectional links • Signal strength can be varied from within the nodes • Energy management is also included • Nodes have failing probabilities • Map for area failures can be specified and used • Other maps can easily used for obstacles, fading, etc. (implementation is similar)

11. Network Architecture • Central Manager • Used as a central database • Its main function: stores the connectivity map and updates it upon request • It takes care of reading additional configuration files and sending the information • It is hidden from the display, communication with it is done only with sendDirect() function • Sensor nodes

12. Sensor Node Architecture • Sensor node architecture: • Layer 0 • Sensor • Energy manager • Blackboard • Application • Custom network layers

13. Mobility Issues • Approaches to describe mobility • Each node reports its position after a certain interval. • Simulation precision depends on this interval. • The smallest the interval the longest the simulation time • Each node reports the equation of the curve of its movement • Manager computes the interaction moments and schedules gates connect/disconnect at those moments • Faster execution (almost 4 times in our simulations) • More precise simulation • Graphical display no longer linked to the simulator precision • Random Way Point model as default

14. Energy Management • Implemented using the blackboard • Consumed energy and of the current energy • Data can be accessed from anywhere within a sensor node • Estimation of the lifetime of the node (can be improved by using any desired estimation function) • Warnings can be issued when no energy is left (special behaviours can be implemented in the energy manager; e.g. stop certain components when energy goes beyond a treshhold)

15. Reliability Issues • Two kinds of failures implemented • Node failure probability • Can be specified for each node separately • Available to all the layers inside a node • Can be set to change over the time • Area failure probability • The failure zones are specified as rectangles inside a configuration file • Data is available to all the layers • It can be given any interpretation needed. Easy to extend to a set of maps

16. Other Features (2) • Support for beacons is added (needed by the localization algorithms) • A certain number of nodes have fixed positions • Any node can find out if it is a beacon or not • Each node can be displayed in several ways (useful for debugging and presentations: to highlight the discovered paths, the clusters, etc.) • 3 distinct graphical signs and 10 colors for each one • Can be modified from anywhere inside the node • Modifications are displayed immediately • Simulation precision is no longer related to display update • User can specify the display rate

17. Work in progress • Signal sources: • Support for fixed and mobile beacons • Support for areas of interest • Fixing minor bugs and optimizing the code • Rather use new derived classes than parameters • Finding the best places to place the functionality (manager or layer0) • Trying to create a library of modules • WANTED: 3D graphical display !!!

18. Work in Progress (2) • Tcl/Tk script for: • Easy configuration of the network • Designing the maps, node initial positions, initial values, etc. • Generation of project files

19. Implementation example

20. Discussions • Address where to download the template: http://wwwhome.cs.utwente.nl/~dulman/tools.htm • Email address: s.o.dulman@utwente.nl