How to Calculate Network Migration Time in NS2

To implement the Network migration time using the simulation platform NS2 that refers to the time it takes for a network entity (e.g., a mobile node or a session) to transfer from one network (or access point/base station) to another during the mobility or handoff events. Network migration time is critical in wireless mobile networks in which nodes (such as mobile phones or vehicles) are move among the coverage areas of various base stations or access points. Now, we give key steps and basic procedure to calculate the network migration time within NS2:

Key Steps to Calculate Network Migration Time in NS2:

  1. Set Up a Wireless Mobile Network:
    Make a network with base stations (or access points) and mobile nodes, which move among them.
  2. Simulate Node Mobility:
    We can be used a mobility model to replicate the movement of mobile nodes are among the base stations, activating migration events (handover).
  3. Track Handover Events:
    Track the point upon which the mobile node separates from one base station and connects to another. The migration time is the delay among the last successful packet transmission or reception in the old base station and the initial successful packet transmission or reception in the new base station.
  4. Calculate Migration Time:
    Migration time is computed as the time among the disconnection from the old base station and the connection to the new base station.

Steps to Calculate Migration Time in NS2:

  1. Set Up the Wireless Network with Mobility:
    Make a network with base stations and mobile nodes. Describe the movement of the mobile node among various coverage areas to activate the handover events.
  2. Log the Disconnection and Connection Events:
    We can be used the NS2 trace file to record the time when the mobile node disconnects from the old base station and attacks to the new one.
  3. Calculate the Migration Time:
    Estimate the migration time as the variance among the disconnection time and the reconnection time.

Example Tcl Script to Simulate Network Migration in NS2:

Now, given below is a sample Tcl script that replicates a mobile node moving among various base stations, triggering migration events:

# Create a new simulator instance

set ns [new Simulator]

# Define the simulation area (X and Y dimensions)

set val(x) 500   ;# X dimension of the simulation area

set val(y) 500   ;# Y dimension of the simulation area

set val(stop) 10.0 ;# Simulation end time

# Create a topography object

set topo [new Topography]

$topo load_flatgrid $val(x) $val(y)

# Define wireless channel and propagation model

set chan_1_ [new Channel/WirelessChannel]

set prop_model [new Propagation/TwoRayGround]

# Configure mobile nodes

$ns node-config -adhocRouting AODV \

-llType LL \

-macType Mac/802_11 \

-ifqType Queue/DropTail/PriQueue \

-ifqLen 50 \

-antType Antenna/OmniAntenna \

-propType Propagation/TwoRayGround \

-phyType Phy/WirelessPhy \

-topoInstance $topo \

-channel $chan_1_ \

-agentTrace ON \

-routerTrace ON \

-macTrace ON

# Create base stations (BS0, BS1)

set bs0 [$ns node]

set bs1 [$ns node]

# Set base station positions

$bs0 set X_ 100.0

$bs0 set Y_ 250.0

$bs0 set Z_ 0.0

$bs1 set X_ 400.0

$bs1 set Y_ 250.0

$bs1 set Z_ 0.0

# Create a mobile node

set mobileNode [$ns node]

$mobileNode set X_ 50.0

$mobileNode set Y_ 250.0

$mobileNode set Z_ 0.0

# Define the mobility model for the mobile node (Random Waypoint)

$ns at 0.0 “$mobileNode setdest 450 250 10.0”  ;# Move towards BS1 from BS0

# Attach UDP agents for communication

set udp0 [new Agent/UDP]

set null0 [new Agent/Null]

$ns attach-agent $mobileNode $udp0

$ns attach-agent $bs1 $null0

# Create a CBR traffic source to generate packets

set cbr0 [new Application/Traffic/CBR]

$cbr0 attach-agent $udp0

$cbr0 set packetSize_ 512

$cbr0 set rate_ 1Mb

# Start and stop traffic

$ns at 1.0 “$cbr0 start”

$ns at 8.0 “$cbr0 stop”

# Open trace file to log events

set tracefile [open trace.tr w]

$ns trace-all $tracefile

# Define finish procedure

proc finish {} {

global ns tracefile

$ns flush-trace

close $tracefile

exit 0

}

# End simulation

$ns at $val(stop) “finish”

$ns run

Explanation of the Script:

  1. Base Stations (BS0, BS1):
    Two base stations (BS0 and BS1) are made at various locations to serve as access points for the mobile node.
  2. Mobile Node Movement:
    The mobile node begins near BS0 and moves towards BS1 using the setdest command, replicating a handover situation in which the node migrates from one base station to another.
  3. Traffic Generation:
    A UDP agent and a CBR traffic source are used to generate traffic among the mobile node and BS1. The mobile node migrates from the base stations BS0 to BS1 as it moves.
  4. Logging Events:
    The simulation records all packet transmissions, receptions, and handovers into the trace file.
  1. Detecting Handover (Migration) Events:

The migration time can assess by detecting the exact times when the mobile node separates from BS0 and connects to BS1. It can be done by examining the trace file, where the packet receptions and transmissions are among the mobile node and the base stations are logged.

Example Trace File Output:

r 2.0 _0_ AGT — 512 [0 0 0 0] ——- [0:0 1:0 32 0]

r 4.0 _1_ AGT — 512 [0 0 0 0] ——- [0:0 1:0 32 0]

d 5.0 _0_ RTR — 512 [0 0 0 0] ——- [0:0 1:0 32 0] ;# Last packet received from BS0

r 6.0 _1_ RTR — 512 [0 0 0 0] ——- [0:0 1:0 32 0] ;# First packet received from BS1

In this instance:

  • At time 5.0: The mobile node received its last packet from the base station BS0 before it disconnects.
  • At time 6.0: The mobile node received its first packet from the base station BS1 after the migration.
  1. Calculating Migration Time:

The migration time is the variations among the time the mobile node disconnects from the old base station and attaches to the new base station:

Migration Time=Tconnect_new−Tdisconnect_old\text{Migration Time} = T_{\text{connect\_new}} – T_{\text{disconnect\_old}}Migration Time=Tconnect_new​−Tdisconnect_old​

Using the trace file instance above:

Migration Time=6.0 seconds−5.0 seconds=1.0 seconds\text{Migration Time} = 6.0 \, \text{seconds} – 5.0 \, \text{seconds} = 1.0 \, \text{seconds}Migration Time=6.0seconds−5.0seconds=1.0seconds

Bash Script to Calculate Migration Time:

# Extract the last packet reception time from the old base station (BS0)

disconnect_time=$(grep “^d” trace.tr | grep “_0_” | tail -1 | awk ‘{print $2}’)

# Extract the first packet reception time from the new base station (BS1)

connect_time=$(grep “^r” trace.tr | grep “_1_” | head -1 | awk ‘{print $2}’)

# Calculate migration time

migration_time=$(echo “$connect_time – $disconnect_time” | bc)

echo “Migration Time: $migration_time seconds”

This script:

  • Extorts the last packet received from the old base station (disconnect time).
  • Extracts the first packet received from the new base station (connect time).
  • Computes the variance to obtain the migration time.

Summary of Steps:

  1. Set Up the Wireless Network: Describe base stations (or access points) and mobile nodes within NS2.
  2. Simulate Node Mobility: We can be used a mobility model to move the mobile node among the base stations, activating a handover (migration).
  3. Track Disconnection and Connection Events: We can use the trace file to log the times at which point the mobile node disconnects from one base station and connects to the next.
  4. Calculate Migration Time: Measure the migration time as the variance among the disconnection time and the reconnection time.

Throughout this manual, we had shown how to compute the Network Migration time in the virtual environment NS2 via simplified approach with examples. Further informations will be shared on this topic rely on your requirements.

Keep in contact with us, and we’ll assist you with timely delivery and the best results possible. It is best to seek professional assistance in order to calculate Network Migration Time using the NS2 tool.