How to Calculate Transmission Quality in NS2

To calculate Transmission quality in NS2 has needs to define the overall performance of a network in terms of how efficiently it transfers information from a source to a destination. Transmission quality is usually measured using several metrics that has Packet Delivery Ratio (PDR), Throughput, Latency, Jitter, Packet Loss, and Error Rates. We can compute these parameters from the NS2 trace file and use them to evaluate the transmission quality of the network.

The given below is the brief approach to calculate the transmission quality in ns2:

Key Metrics for Transmission Quality:

  1. Packet Delivery Ratio (PDR): The ratio of the number of successfully received packets to the number of packets delivers by the source.
  2. Throughput: The amount of effectively carried content over a period of time that commonly evaluated in bits per second or packets per second.
  3. Latency (End-to-End Delay): The time it takes for a packet to travel from the source to the destination.
  4. Jitter: The variation in packet delay over time.
  5. Packet Loss: The percentage of packets that were sent nevertheless never received.
  6. Error Rate: The number of degraded packets compared to the total packets sent.

Steps to Calculate Transmission Quality in NS2

  1. Set Up NS2 to Simulate Data Transmission:

Initiate by configure a simple NS2 simulation in which information is routed from a source node to a destination node. In this sample, we replicate a network in which a source node transmits data to a destination node using UDP.

Example TCL Script for Data Transmission:

# Create the simulator

set ns [new Simulator]

# Define the topology (e.g., 1000m x 1000m area)

set topo [new Topography]

$topo load_flatgrid 1000 1000

# Create two nodes

set node_(0) [$ns node]

set node_(1) [$ns node]

# Define the wireless channel

set chan_ [new Channel/WirelessChannel]

$node_(0) set channel_ $chan_

$node_(1) set channel_ $chan_

# Attach UDP agents for data transmission

set udp0 [new Agent/UDP]

set sink [new Agent/Null]

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

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

$ns connect $udp0 $sink

# Set up CBR traffic (Constant Bit Rate)

set cbr0 [new Application/Traffic/CBR]

$cbr0 attach-agent $udp0

$cbr0 set packetSize_ 512        ;# Packet size in bytes

$cbr0 set rate_ 1Mb              ;# Transmission rate

# Start and stop the traffic

$ns at 1.0 “$cbr0 start”

$ns at 10.0 “$cbr0 stop”

# Enable tracing to capture packet transmission and reception

set tracefile [open out.tr w]

$ns trace-all $tracefile

# Close the trace file at the end

proc finish {} {

global ns tracefile

$ns flush-trace

close $tracefile

exit 0

}

# End simulation at time 12 seconds

$ns at 12.0 “finish”

In this sample, 512-byte packets are routed from node 0 to node 1 at a rate of 1 Mbps from time 1.0 seconds to 10.0 seconds.

  1. Trace File Analysis:

NS2 creates a trace file (out.tr) that includes packet transmission and reception events. We can evaluate this trace file to extract data about packet delivery, packet loss, latency, and jitter.

Example Trace File Entries:

s 2.000000000 _0_ AGT  — 512 cbr 0 0.0 1.0 1.0

r 2.000500000 _1_ AGT  — 512 cbr 0 0.0 1.0 1.0

s 3.000000000 _0_ AGT  — 512 cbr 1 0.0 2.0 2.0

r 3.000500000 _1_ AGT  — 512 cbr 1 0.0 2.0 2.0

Here:

  • s: Packet sent event.
  • r: Packet received event.
  • _0_ and _1_: Node IDs (source node _0_, destination node _1_).
  • AGT: Application layer.
  • 512: Packet size in bytes.
  1. Calculating Key Metrics:
  2. a) Packet Delivery Ratio (PDR):

The Packet Delivery Ratio is the ratio of the number of successfully received packets to the number of packets sent.

PDR=Number of Received PacketsNumber of Sent Packets×100\text{PDR} = \frac{\text{Number of Received Packets}}{\text{Number of Sent Packets}} \times 100PDR=Number of Sent PacketsNumber of Received Packets​×100

We can compute PDR by counting the s (sent) and r (received) events in the trace file.

AWK Script to Calculate PDR:

BEGIN {

sent_packets = 0;

received_packets = 0;

}

# Count the number of sent packets

$1 == “s” && $4 == “_0_” && $7 == “cbr” {

sent_packets++;

}

# Count the number of received packets

$1 == “r” && $4 == “_1_” && $7 == “cbr” {

received_packets++;

}

END {

pdr = (received_packets / sent_packets) * 100;

print “Packet Delivery Ratio (PDR): ” pdr “%”;

}

Save the script as pdr.awk and execute it on the trace file:

awk -f pdr.awk out.tr

  1. b) Throughput:

Throughput is the amount of successfully delivered data per unit of time, frequently measured in bits per second (bps).

Throughput=Total Received Data (in bits)Total Simulation Time (in seconds)\text{Throughput} = \frac{\text{Total Received Data (in bits)}}{\text{Total Simulation Time (in seconds)}}Throughput=Total Simulation Time (in seconds)Total Received Data (in bits)​

AWK Script to Calculate Throughput:

BEGIN {

received_data = 0;

start_time = 1.0;

end_time = 10.0;

}

# Calculate total received data in bits

$1 == “r” && $4 == “_1_” && $7 == “cbr” {

packet_size = $8;  # Packet size in bytes

received_data += packet_size * 8;  # Convert to bits

}

END {

duration = end_time – start_time;

throughput = received_data / duration;

print “Throughput (bps): ” throughput;

}

Execute the script to calculate throughput:

awk -f throughput.awk out.tr

  1. c) End-to-End Delay (Latency):

End-to-end delay is the time it takes for a packet to travel from the source to the destination. For each received packet, delay is the difference among the packet’s reception time and the corresponding transmission time.

Delay=Time of Reception−Time of Transmission\text{Delay} = \text{Time of Reception} – \text{Time of Transmission}Delay=Time of Reception−Time of Transmission

AWK Script to Calculate Delay:

BEGIN {

total_delay = 0;

received_packets = 0;

}

# Calculate the delay for each packet

$1 == “r” && $4 == “_1_” && $7 == “cbr” {

delay = $2 – packet_time[$10];  # Subtract transmission time from reception time

total_delay += delay;

received_packets++;

}

END {

avg_delay = total_delay / received_packets;

print “Average End-to-End Delay (seconds): ” avg_delay;

}

Execute the script to compute delay:

awk -f delay.awk out.tr

  1. d) Jitter:

Jitter is the variation in packet delay. It is computed as the difference among successive packet delays.

AWK Script to Calculate Jitter:

BEGIN {

prev_delay = 0;

total_jitter = 0;

received_packets = 0;

}

# Calculate jitter for each packet

$1 == “r” && $4 == “_1_” && $7 == “cbr” {

delay = $2 – packet_time[$10];

if (received_packets > 0) {

jitter = delay – prev_delay;

total_jitter += jitter;

}

prev_delay = delay;

received_packets++;

}

END {

avg_jitter = total_jitter / received_packets;

print “Average Jitter (seconds): ” avg_jitter;

}

Execute the script to compute jitter:

awk -f jitter.awk out.tr

  1. e) Packet Loss:

Packet loss is the percentage of packets that were sent but never received.

Packet Loss=Sent Packets−Received PacketsSent Packets×100\text{Packet Loss} = \frac{\text{Sent Packets} – \text{Received Packets}}{\text{Sent Packets}} \times 100Packet Loss=Sent PacketsSent Packets−Received Packets​×100

We can compute packet loss by comparing the number of sent and received packets.

  1. Conclusion:

To compute transmission quality in NS2, follow these steps:

  1. Simulate data transmission and create a trace file.
  2. Analyse the trace file using AWK or other tools to extract parameters like PDR, throughput, delay, jitter, and packet loss.
  3. Calculate these metrics to evaluate the overall transmission quality.

In this demonstration we learned to calculate the Transmission quality in the network using the ns2 tool. If you need more details about how the Transmission quality will perform in other simulation tool, we will provide it.

To assess Transmission Quality using the NS2 tool for your project, please reach out to us ns2project.com  for exceptional support and clear explanations during the course of your project. We focus on various metrics, including Packet Delivery Ratio (PDR), Throughput, Latency, Jitter, Packet Loss, and Error Rates, tailored to your specific needs.