How to Calculate Transmission Reliability in NS2

To calculate transmission reliability in ns2 has needs to define the possibility which a packet is successfully routed from a source node to a destination node without errors or losses. These parameters are especially significant in wireless networks, in which packet loss can happen because of interference, fading, mobility, congestion, or weak signals.

Here’s a step-by-step guide on how to calculate transmission reliability in NS2:

Step-by-Step Implementation:

  1. Define Transmission Reliability:
  • Transmission Reliability is the ratio of successfully received packets to the total number of transmitted packets.
  • The formula is: Transmission Reliability=Number of Successfully Received PacketsNumber of Transmitted Packets×100\text{Transmission Reliability} = \frac{\text{Number of Successfully Received Packets}}{\text{Number of Transmitted Packets}} \times 100Transmission Reliability=Number of Transmitted PacketsNumber of Successfully Received Packets​×100
  • A transmission reliability of 100% means all transferred packets were successfully received.
  1. Set Up the Network Scenario:

Describe the simulation scenario in NS2 with a source node transmitting packets to a destination node.

Example setup:

# Create Simulator

set ns [new Simulator]

# Create a topology (e.g., a 1000m x 1000m area)

set topo [new Topography]

$topo load_flatgrid 1000 1000

# Create a wireless channel

set chan_ [new Channel/WirelessChannel]

# Create two nodes

set node_(0) [$ns node]

set node_(1) [$ns node]

# Set positions of the nodes

$node_(0) set X_ 100

$node_(0) set Y_ 200

$node_(1) set X_ 500

$node_(1) set Y_ 200

# Set communication parameters (if required)

set netif_ [new Phy/WirelessPhy]

$netif_ set Pt_ 0.2818   ;# Transmission power

# Attach agents to the nodes

set udp0 [new Agent/UDP]

set sink [new Agent/Null]

$ns attach-agent $node_(0) $udp0

$ns attach-agent $node_(1) $sink

# Create a CBR traffic source

set cbr0 [new Application/Traffic/CBR]

$cbr0 set packetSize_ 512    ;# Packet size in bytes

$cbr0 set rate_ 0.1Mb        ;# Traffic rate (0.1 Mbps)

$cbr0 attach-agent $udp0

# Connect source and sink

$ns connect $udp0 $sink

# Start and stop the CBR traffic

$ns at 1.0 “$cbr0 start”

$ns at 5.0 “$cbr0 stop”

# Run the simulation

$ns at 10.0 “finish”

  1. Collecting Transmission Data:

To compute transmission reliability, we need to gather the following data:

  • The number of packets transmitted by the source node.
  • The number of packets received successfully by the destination node.

NS2 delivers trace files that log all packet-level events, like when a packet is routed, received, or dropped.

  1. Enable Trace Files:

Add the following lines to TCL script to enable tracing:

# Open the trace file to store the results

set tracefile [open out.tr w]

$ns trace-all $tracefile

# Run the simulation and flush the output

proc finish {} {

global ns tracefile

$ns flush-trace

close $tracefile

exit 0

}

  1. Analyzing the Trace File:

After executing the simulation, NS2 will create a trace file (out.tr) encompassing events such as packet transmissions, receptions, and drops. Here’s an sample of a line in the trace file:

r 1.000000000 _1_ AGT  — 512 cbr 0 0.0 1.0 1.0

The key information we need to extract from the trace file is:

  • “s”: Sent packets (lines where packets are sent from the source).
  • “r”: Received packets (lines where packets are received at the destination).
  1. Calculating Transmission Reliability Using AWK:

We can use an AWK script to parse the trace file and estimate the number of sent and received packets.

AWK Script to Calculate Transmission Reliability:

BEGIN {

transmitted = 0;

received = 0;

}

# Count transmitted packets from node 0

$1 == “s” && $3 == “_0_” && $4 == “AGT” {

transmitted++;

}

# Count received packets at node 1

$1 == “r” && $3 == “_1_” && $4 == “AGT” {

received++;

}

END {

reliability = (received / transmitted) * 100;

printf(“Transmission Reliability: %.2f%%\n”, reliability);

}

Execute the AWK script on the generated trace file:

awk -f reliability.awk out.tr

  1. Explanation of the AWK Script:
  • The script counts the number of packets routed from node 0 and the number of packets received by node 1.
  • It then estimates transmission reliability as the ratio of received packets to transferred packets, multiplied by 100.
  1. Enhancing the Script:
  • Packet Dropping: we can expand the script to also count packet drops (lines with d events) to added to evaluate why some packets were not received.
  • Multiple Flows: If we have multiple flows or more complex topologies, adapt the script to track transmissions and receptions for each flow individually.
  1. Factors Affecting Transmission Reliability:

Transmission reliability in wireless networks can be impacted by numerous factors:

  • Distance between nodes: Greater distances cause to increased packet loss because of signal attenuation.
  • Interference: Multiple nodes interacting on the same channel that cause to collisions and packet loss.
  • Mobility: Moving nodes can move out of range or experience connectivity difficulties.
  • Congestion: High traffic volumes can overload the network, that leads packet drops because of buffer overflows.
  • Link Quality: Environmental factors such as a fading, noise, or obstacles can impact the link quality.
  1. Improving Transmission Reliability:
  • Increase transmission power to enhance signal strength.
  • Adjust routing protocols to use more reliable routes.
  • Implement error correction mechanisms such as Automatic Repeat request (ARQ) to get better the lost packets.

We demonstrate and provide the valuable insights on how to calculate and simulate the results for transmission reliability in ns2 tool. If you need more details regarding the transmission reliability we will provide it.

We specialize in addressing issues such as interference, fading, mobility, congestion, and weak signals pertinent to your projects. To assess Transmission Reliability using the NS2 tool for your project, please reach out to us for exceptional guidance and clear explanations during the course of your project.