How to Implement Network Range Free Localization in NS2

To implement Network Range-Free Localization in NS2, we need to replicate a network scenario in which the nodes localize themselves without depending on precise distance or angle measurements that is characteristic of range-free localization methods. The below is the guide on how to approach this in ns2:

Step-by-Step Implementation:

  1. Understanding Range-Free Localization
  • Range-Free Localization methods do not relay on distance or angle measurements. In its place, they use network connectivity, hop count, or proximity to anchors (nodes with known locations).
  • Popular range-free techniques contain DV-Hop, Centroid Localization, and APIT (Approximate Point-In-Triangulation).
  1. Setting up NS2 Environment
  • Make sure we have NS2 installed on system. If not, you can download and install it from here.
  • Validate if we have mobility models and wireless communication libraries integrated, by way of they will be vital for a localization simulation.
  1. Choose a Range-Free Algorithm
  • Decide which range-free localization algorithm wants to executed. For this guide, we will use DV-Hop as an example.
  1. Create the TCL Script
  • NS2 uses TCL scripts for replicate the scenarios. We will need to generate a .tcl file to define the simulation environment.

Example DV-Hop Simulation:

# Create simulator instance

set ns [new Simulator]

# Create trace and nam files

set tracefile [open dvhop.tr w]

set namfile [open dvhop.nam w]

$ns trace-all $tracefile

$ns namtrace-all $namfile

# Define topography for wireless nodes

set topo [new Topography]

$topo load_flatgrid 1000 1000  ;# Set the simulation area

# Define a node configuration

set opt(chan)       Channel/WirelessChannel

set opt(prop)       Propagation/TwoRayGround

set opt(netif)      Phy/WirelessPhy

set opt(mac)        Mac/802_11

set opt(ifq)        Queue/DropTail/PriQueue

set opt(ll)         LL

set opt(ant)        Antenna/OmniAntenna

set opt(x)          1000    ;# X-axis range

set opt(y)          1000    ;# Y-axis range

# Define some node parameters

set opt(nn) 50  ;# Number of nodes

# Creating wireless nodes

for {set i 0} {$i < $opt(nn)} {incr i} {

set node_($i) [$ns node]

$node_($i) random-motion 1  ;# Enable node mobility

}

# Mobility setup for the nodes

set god_ [create-god $opt(nn)]  ;# Generalized operation director

# Create mobility scenario for random node movement

for {set i 0} {$i < $opt(nn)} {incr i} {

$ns at 0.0 “$node_($i) setdest [expr rand()*1000] [expr rand()*1000] [expr rand()*10]”

}

# Add anchor nodes (nodes with known positions)

set anchor_1 [expr int(rand()*$opt(nn))]

set anchor_2 [expr int(rand()*$opt(nn))]

set anchor_3 [expr int(rand()*$opt(nn))]

# Initial position assignment for anchors

$node_($anchor_1) set X_ 100

$node_($anchor_1) set Y_ 100

$node_($anchor_2) set X_ 900

$node_($anchor_2) set Y_ 100

$node_($anchor_3) set X_ 500

$node_($anchor_3) set Y_ 900

# Hop count calculation (DV-Hop)

proc dvhop {} {

global ns node_ anchor_1 anchor_2 anchor_3

for {set i 0} {$i < $opt(nn)} {incr i} {

if {($i != $anchor_1 && $i != $anchor_2 && $i != $anchor_3)} {

# Calculate hop count from the nearest anchor nodes

# Implement DV-Hop algorithm here

}

}

}

$ns at 5.0 “dvhop”

# Define stopping time and start the simulation

$ns at 50.0 “finish”

proc finish {} {

global ns tracefile namfile

close $tracefile

close $namfile

$ns halt

}

$ns run

  1. Implementing the DV-Hop Algorithm
  • The above script that has placeholders for executing the DV-Hop algorithm. We need to execute the actual logic that calculates hop counts from each node to the anchors and then calculate the node positions according to those hop counts.
  • Key steps in DV-Hop:
    1. Anchor Flooding: Anchors flood their position information to all other nodes.
    2. Hop Count Calculation: Each node keeps track of the least hop count to each anchor.
    3. Distance Estimation: Nodes calculate their distance to anchors according to average hop distance.
    4. Position Calculation: Nodes use triangulation according to estimated distances to multiple anchors to localize themselves.
  1. Modify Mobility Models (Optional)
  • We can adjust the mobility patterns of nodes to mimic different real-world scenarios such as random waypoint, group mobility, etc.
  1. Running the Simulation
  • After composing the TCL script, execute it using NS2 with the following command:

ns dvhop.tcl

  1. Analysing Results
  • After running the simulation, we will have a trace file (dvhop.tr) and a NAM visualization file (dvhop.nam).
  • Use NAM to envision the node movements and localization process.
  • Measure the trace file to study the performance of localization algorithm such as localization error, number of hops, etc.
  1. Further Enhancements
  • Add different parameters to script such as localization accuracy, energy consumption.
  • Test with diverse mobility models and network sizes.

In this given module, we had explicitly focussed the novel information on how to execute the Range-Free Localization that were executed using ns2 tool that is used to localize themselves without depending on any features. If you need more information regarding this process we will explain it based on your needs.

We provide assistance in generating optimal thesis ideas and topics that align with your specific interests. For effective implementation results related to Network Range Free Localization using the NS2 tool, you may consult the team at ns2project.com