How to Calculate Network Communication Links Quality in NS2

To calculate the quality of communication links using NS2 (Network Simulator 2), which is a significant performance metric, particularly in the wireless networks in which the link quality can be differed because of the signal interference, packet losses, or congestion. This link quality can estimate rely on numerous factors like Packet Loss Ratio (PLR), Signal-to-Noise Ratio (SNR), Bit Error Rate (BER), throughput, and delay. To compute the network communication link quality within NS2, we can be aimed on the vital metrics such as Packet Delivery Ratio (PDR) or Packet Loss Ratio (PLR), end-to-end delay, and throughput for every communication link among the nodes. Given below is some key metrics and sufficient stepwise procedure on how to compute it in NS2:

Key Metrics for Link Quality Evaluation:

Packet Delivery Ratio (PDR): The percentage of effectively delivered packets.
Packet Loss Ratio (PLR): The percentage of packets, which were lost in the course of transmission.
End-to-End Delay: The time it takes for a packet to travel from the origin to end.
Throughput: The amount of data effectively delivered over a particular period.
Bit Error Rate (BER): The rate at which errors are happen during transmission (for wireless or error-prone links).

Steps to Calculate Communication Link Quality in NS2

Set Up NS2 Simulation:

Initially, we require to configure the simulation in which the packets are transferred among the nodes, and communication links among nodes can be assessed rely on metrics such as PDR, PLR, delay, and throughput.

Example TCL Script for Link Evaluation:

# Create the simulator

set ns [new Simulator]

# Define the topology with two nodes: source and destination

set node_(0) [$ns node]

set node_(1) [$ns node]

# Create a duplex link between the nodes (1 Mbps bandwidth, 10ms delay)

$ns duplex-link $node_(0) $node_(1) 1Mb 10ms DropTail

# Attach UDP agents to nodes for sending and receiving data

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 on the UDP agent

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

# End the simulation after 12 seconds

proc finish {} {

global ns tracefile

$ns flush-trace

close $tracefile

exit 0

}

# End simulation at 12 seconds

$ns at 12.0 “finish”

In this simulation:

A source node delivers packets to an end node across a 1 Mbps link with 10 ms delay.
The link quality can estimate by evaluate the trace file to calculate metrics such as PDR, PLR, delay, and throughput.

Trace File Overview:

The simulation environment NS2 generates a trace file (out.tr), which records the packet events, containing the transmissions, receptions, and packet losses. This file will use to assess the link quality metrics.

Example Trace File Entries:

plaintext

Copy code

s 2.000000000 _0_ AGT — 512 cbr 0 0.0 1.0 1.0

r 2.010000000 _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

d 3.500000000 _1_ AGT — 512 cbr 1 0.0 2.0 2.0

In this sample:

s: Packet sent event.
r: Packet received event.
d: Packet dropped event (which indicates packet loss).
0 and 1: Node IDs (source _0_ and destination _1_).
512: Packet size in bytes.

Metrics Calculation:
a) Packet Delivery Ratio (PDR):

The packet delivery ratio is the ratio of the number of effectively received packets to the number of the packets sent. It can be calculated the reliability of the communication link.

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

AWK Script to Calculate PDR:

BEGIN {

sent_packets = 0;

received_packets = 0;

}

# Count sent packets from source node (_0_)

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

sent_packets++;

}

# Count received packets at destination node (_1_)

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

received_packets++;

}

END {

pdr = (received_packets / sent_packets) * 100;

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

}

b) Packet Loss Ratio (PLR):

PLR is the ratio of packets lost to packets are transferred and it estimates how often packets are lost during transmission.

PLR=Number of Lost PacketsNumber of Sent Packets×100\text{PLR} = \frac{\text{Number of Lost Packets}}{\text{Number of Sent Packets}} \times 100PLR=Number of Sent PacketsNumber of Lost Packets×100

AWK Script to Calculate PLR:

BEGIN {

sent_packets = 0;

dropped_packets = 0;

}

# Count sent packets from source node (_0_)

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

sent_packets++;

}

# Count dropped packets at destination node (_1_)

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

dropped_packets++;

}

END {

plr = (dropped_packets / sent_packets) * 100;

print “Packet Loss Ratio (PLR): ” plr “%”;

}

c) End-to-End Delay:

End-to-end delay is the time it takes for a packet to travel from the origin to the end. For every received packet, we can be assessed the delay as:

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 Average Delay:

BEGIN {

total_delay = 0;

received_packets = 0;

}

# Store the time each packet was sent

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

packet_time[$10] = $2; # Store the transmission time indexed by packet ID

}

# Calculate the delay for each received 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: ” avg_delay ” seconds”;

}

d) Throughput:

Throughput is the number of data effectively delivered per unit time that normally computed in bits per second (bps).

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

AWK Script to Calculate Throughput:

BEGIN {

received_data = 0;

start_time = 1.0; # Start time of the download (in seconds)

end_time = 10.0; # End time of the download (in seconds)

}

# Process received packets at the destination (_1_)

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

received_data += $8 * 8; # Convert packet size from bytes to bits

}

END {

duration = end_time – start_time;

throughput = received_data / duration; # Throughput in bits per second (bps)

print “Total Data Received (bits): ” received_data;

print “Throughput (bps): ” throughput;

}

Running the AWK Scripts:

We can be saved the AWK scripts (e.g., for PDR, PLR, delay, and throughput) as isolated files and then run them on the generated trace file (out.tr).

For instance, to estimate PDR:

awk -f pdr.awk out.tr

To calculate PLR:

awk -f plr.awk out.tr

To calculate average delay:

awk -f delay.awk out.tr

To calculate throughput:

awk -f throughput.awk out.tr

Conclusion:

To compute the network communication link quality in NS2:

Configure the simulation and permit the packet tracing.
Examine the trace file using AWK scripts to calculate the metrics like Packet Delivery Ratio (PDR), Packet Loss Ratio (PLR), end-to-end delay, and throughput.
These metrics will be provided a complete assessment of the quality of the communication link among the nodes.

Finally, we had understand the concepts and approach on how to compute the Network Communication Links Quality within NS2 using AWK scripts. Moreover, we will be offered more comprehensive details with some instance as per your requirements.

Provide us with all relevant parameter details, and we assure you that we will deliver the best comparative project results. Calculating the quality of network communication links in NS2 can be quite challenging, so we encourage you to stay connected with us for expert guidance. Our focus includes analyzing Packet Delivery Ratio (PDR), Packet Loss Ratio (PLR), end-to-end delay, and throughput for each communication link between nodes. Please share your details with us to achieve optimal results.