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energy efficient sensor networks
Presentation Overview
OMNeT++ Introduction
Sensor Network Template
Implementation Example
Discussion and future work
energy efficient sensor networks
OMNeT++ Introduction
energy efficient sensor networks
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
energy efficient sensor networks
OMNeT++ Features (2)
Simulated objects are represented by modulesModules 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
energy efficient sensor networks
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
energy efficient sensor networks
OMNeT++ Features (4)
What is missing or not working as wanted:Mobile entities and wireless communication between them are not includedStatic data types not allowed
For storing data needed by all the modules a central manager has to be createdCommunication 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 parametersVery slow 2D graphical interface made in Tk
energy efficient sensor networks
Sensor Network Template
energy efficient sensor networks
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
energy efficient sensor networks
Template Description (2)
Characteristics:Implements mobility (Random Way Point alg.)Wireless communication
Simulated by dynamically connecting modules within transmission range
Unidirectional linksSignal strength can be varied from within the nodesEnergy management is also includedNodes have failing probabilitiesMap for area failures can be specified and used
Other maps can easily used for obstacles, fading, etc. (implementation is similar)
energy efficient sensor networks
Network Architecture
Central ManagerUsed 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
energy efficient sensor networks
Sensor Node Architecture
Sensor node architecture:Layer 0
Sensor
Energy manager
Blackboard
Application
Custom network layers
energy efficient sensor networks
Mobility Issues
Approaches to describe mobilityEach 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 momentsFaster execution (almost 4 times in our simulations)More precise simulationGraphical display no longer linked to the simulator precision
Random Way Point model as default
energy efficient sensor networks
Energy Management
Implemented using the blackboardConsumed 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)
energy efficient sensor networks
Reliability Issues
Two kinds of failures implementedNode 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
energy efficient sensor networks
Other Features (2)
Support for beacons is added (needed by the localization algorithms)
A certain number of nodes have fixed positionsAny 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 oneCan be modified from anywhere inside the nodeModifications are displayed immediately
Simulation precision is no longer related to display update
User can specify the display rate
energy efficient sensor networks
Work in progress
Signal sources:Support for fixed and mobile beaconsSupport for areas of interest
Fixing minor bugs and optimizing the codeRather use new derived classes than parametersFinding the best places to place the functionality (manager or layer0)
Trying to create a library of modules
WANTED: 3D graphical display !!!
energy efficient sensor networks
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
energy efficient sensor networks
Implementation example
energy efficient sensor networks
Discussions
Address where to download the template:http://wwwhome.cs.utwente.nl/~dulman/tools.htm
Email address:[email protected]
