How to Calculate Network Link Strength in NS2
To calculate the network link strength using NS2 (Network Simulator 2), we commonly estimate the quality of the link among two nodes in terms of metrics like signal strength, packet loss rate, or throughput. The simulation platform NS2 does not have a direct metric called “link strength,” however we can derive it by computing particular performance features. Given below is a brief process on how to approach it in NS2:
Steps to Calculate Link Strength
- Measure Signal Strength (RSSI):
- We can be used the shadowing or two-ray ground propagation model to replicate signal strength among the nodes. The signal strength can assess as part of the wireless simulation.
- Configure a wireless scenario including the correct propagation model, and then NS2 will mimic signal degradation rely on distance, obstacles, etc.
- Measure Packet Loss Rate:
- We can be estimated how many packets are dropped or lost in the communication among two nodes.
- To record packet drops in NS2, we can be used a trace file and evaluate the dropped packets for particular links. It indirectly indicates the quality or strength of the link.
- Throughput:
- Compute the data throughput on the link. Higher throughput commonly shows a better or stronger link.
- We can use a trace file in NS2 to log the packet transmission events and estimate the throughput as the amount of data effectively received over a period of time.
Example Script to Measure Throughput:
- Simulation Setup: Make a simple simulation in NS2 containing two wireless nodes. We can use a propagation model such as TwoRayGround to model signal propagation.
- Trace File Generation: We require to generate a trace file in the course of the simulation, which encompasses the data regarding sent, received, and dropped packets.
set ns [new Simulator]
set tracefile [open trace.tr w]
$ns trace-all $tracefile
set node1 [$ns node]
set node2 [$ns node]
# Set up the wireless channel
set opt(chan) Channel/WirelessChannel
set opt(prop) Propagation/TwoRayGround
# Create a UDP agent to simulate data traffic
set udp1 [new Agent/UDP]
set null [new Agent/Null]
$ns attach-agent $node1 $udp1
$ns attach-agent $node2 $null
set cbr [new Application/Traffic/CBR]
$cbr attach-agent $udp1
$cbr set packetSize_ 1000
$cbr set rate_ 1Mb
$ns connect $udp1 $null
# Run the simulation
$ns at 0.0 “$cbr start”
$ns at 5.0 “finish”
proc finish {} {
global ns tracefile
$ns flush-trace
close $tracefile
exit 0
}
$ns run
- Throughput Calculation from Trace File: We can be used a script to parse the trace file and compute the throughput, after running the simulation. The below example indicates how we might process a trace file to count the received packets and compute the throughput.
# Count the number of packets received at node2
grep “r” trace.tr | awk ‘{if ($3 == “Node2” && $5 == “TCP”) print $0}’ | wc -l
- Calculate Link Strength:
- Signal Strength (RSSI): It can evaluate from the propagation models within the simulation.
- Packet Loss Rate: It can be computed by comparing the transferred and received packets in the trace file.
- Throughput: Estimated as the total data received over the time period.
Merging these metrics can support to derive an overall “link strength” for the communication link in the NS2 simulation.
We had given simple calculation steps with instances are supports you to compute the Network Link Strength using NS2 simulation platform. If you want more informations on this topic, we will be shared in upcoming manual.
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