How to Start Cellular Topology Projects Using NS2

To start a Cellular Topology project using Network Simulator 2 (NS2) which replicates a cellular network in which numerous mobile nodes are interact via fixed base stations (cells). Cellular networks are typically leveraged within mobile communication systems, and its simulation offered insights that contain handovers, cell coverage, and interference.

Below is a step-by-step mechanism to configure and replicate a Cellular Topology project in NS2:

Steps to Start Cellular Topology Projects in NS2

  1. Understand Cellular Topology
  • Cellular Topology:
    • It includes mobile nodes (MNs) to interact via base stations (BSs) in described cell areas.
    • It supports handovers once mobile nodes travel from one cell to another cell.
  • Key Components:
    • Base Stations (BS): Fixed nodes are performing like access points for mobile interaction.
    • Mobile Nodes (MN): Nodes, which transfer through the cells.
    • Cells: Coverage areas that are handled with the support of base stations.
  1. Set Up NS2
  1. Install NS2:
    • We can set up NS2 and confirm their functionality:

ns example.tcl

  1. Tools for Analysis:
    • NAM (Network Animator) tool is designed for visualization.
    • Trace Analysis tools such as AWK to estimate the performance parameters.
  1. Plan the Cellular Topology
  • Example Setup:
    • A grid of base stations to include diverse areas.
    • Mobile nodes are traveling through the coverage areas.
  • Metrics to Analyze:
    • Throughput and packet delivery ratio.
    • Handover delays.
    • Latency during mobility.
  1. Write the Simulation Script

Step 4.1: Create the TCL Script

We will need to store the tcl script like cellular_topology.tcl with NS2.

Step 4.2: Initialize the Simulator

Configure the simulator and tracing:

set ns [new Simulator]

set tracefile [open trace.tr w]

$ns trace-all $tracefile

set namfile [open cellular_topology.nam w]

$ns namtrace-all $namfile

Step 4.3: Define Base Stations and Mobile Nodes

  • Make base stations and mobile nodes in NS2:

# Base Stations

set bs1 [$ns node]

set bs2 [$ns node]

set bs3 [$ns node]

# Mobile Nodes

set mn1 [$ns node]

set mn2 [$ns node]

Step 4.4: Configure Links

  • We can associate the base stations into the backbone or core network:

# Backbone network links

set core [$ns node]

$ns duplex-link $bs1 $core 10Mb 10ms DropTail

$ns duplex-link $bs2 $core 10Mb 10ms DropTail

$ns duplex-link $bs3 $core 10Mb 10ms DropTail

Step 4.5: Define Mobility for Mobile Nodes

  • We should set up mobility for mobile nodes:

# Mobile Node 1 movement

$ns at 0.0 “$mn1 set X_ 50”

$ns at 0.0 “$mn1 set Y_ 50”

$ns at 0.0 “$mn1 set Z_ 0”

$ns at 5.0 “$mn1 setdest 150 50 10”  ; # Move to new location

# Mobile Node 2 movement

$ns at 0.0 “$mn2 set X_ 100”

$ns at 0.0 “$mn2 set Y_ 150”

$ns at 10.0 “$mn2 setdest 200 150 10”  ; # Move to another cell

Step 4.6: Configure Traffic

Configure traffic flows among the mobile nodes and base stations:

# Traffic from mn1 to core

set udp1 [new Agent/UDP]

$ns attach-agent $mn1 $udp1

set null1 [new Agent/Null]

$ns attach-agent $core $null1

$ns connect $udp1 $null1

set cbr1 [new Application/Traffic/CBR]

$cbr1 attach-agent $udp1

$cbr1 set packetSize_ 512

$cbr1 set rate_ 100kb

$ns at 1.0 “$cbr1 start”

# Traffic from core to mn2

set udp2 [new Agent/UDP]

$ns attach-agent $core $udp2

set null2 [new Agent/Null]

$ns attach-agent $mn2 $null2

$ns connect $udp2 $null2

set cbr2 [new Application/Traffic/CBR]

$cbr2 attach-agent $udp2

$cbr2 set packetSize_ 512

$cbr2 set rate_ 100kb

$ns at 2.0 “$cbr2 start”

Step 4.7: Enable Handoff Simulation

  • Execute the handover once a mobile node transfers via one cell and moves into another cell:

proc handoff {mn old_bs new_bs} {

$old_bs detach-agent $mn

$new_bs attach-agent $mn

}

$ns at 6.0 “handoff $mn1 $bs1 $bs2”

$ns at 11.0 “handoff $mn2 $bs2 $bs3”

Step 4.8: Finalize the Script

We need to integrate the simulation end conditions in the script:

$ns at 15.0 “finish”

proc finish {} {

global ns tracefile namfile

$ns flush-trace

close $tracefile

close $namfile

exec nam cellular_topology.nam &

exit 0

}

$ns run

  1. Run the Simulation
  1. We should store the simulation tcl script like cellular_topology.tcl.
  2. Execute the script in NS2:

ns cellular_topology.tcl

  1. Go to the NAM file for envisioning the cellular topology:

nam cellular_topology.nam

  1. Analyze Results
  • Trace File Analysis:
    • Examine the trace.tr for performance parameters such as handover delay and throughput.
    • Example AWK script to compute the throughput:

awk ‘{if ($1 == “r” && $4 == “udp”) sum += $8} END {print “Throughput: “, sum}’

  • Key Metrics:
    • Handover Delay: Estimate the duration for handover.
    • Throughput: Measure data transfer effectiveness.
    • Packet Delivery Ratio (PDR): Compute the data delivery reliability.
  1. Expand the Simulation
  1. Test with More Mobile Nodes:
    • Integrate additional nodes for analysing the scalability.
  2. Simulate Network Failures:
    • Launch base station or link failures for simulation:

$ns at 8.0 “$ns link-fail $bs2 $core”

  1. Implement Advanced Handoff:
    • Make use of mechanism to automate and enhance the advanced handover decisions.
  2. Evaluate Multicast Communication:
    • Replicate the scenarios in which a base station transmits the information to several mobile nodes.
  1. Document the Project
  • Objective: Define the primary aim of project to replicate a cellular topology.
  • Setup: Specify the nodes, links, and traffic sets up.
  • Results: It offers simulation parameters such as handover delay, throughput, and PDR.
  • Conclusions: Sum up outcomes and optimization chances.

Through the entire manual, we can know the general concepts and simulation process for simulating and extending the Cellular Topology Projects using the tool NS2 which is a robust network simulator. Additional specific details about this subject will also be provided.