How to Calculate Communication Range in NS2

To calculate the communication range in Network Simulator 2 (NS2), we have to measure the distance which a node can take to successfully communicate with another node. It is specified by the node’s transmission power and the propagation model being used in the simulation. This range can be directly or indirectly fix over different metrics and based on the configuration, ns2 will manage the actual communication activities.

Here’s how you can calculate and simulate communication range in NS2:

Step-by-Step Implementation:

  1. Propagation Models:

In NS2, the communication range is impacted by the radio propagation model used in the simulation. NS2 assists multiple propagation models include:

  • Free Space Model: This model assumes a line-of-sight (LOS) path amongst the transmitter and receiver, making it suitable for environments with less obstruction.
  • Two-Ray Ground Model: This model considers both the direct path and a ground-reflected path, making it more precise for longer distances.
  • Shadowing Model: This model responsible for variations in signal strength because of obstructions and shadowing effects.
  1. Define Communication Range Parameters:

To measure the communication range, you need to set key parameters such as:

  • Transmission Power (Pt_): The power level at which the node transmits.
  • Gain (Gt_, Gr_): The antenna gain at the transmitter and receiver.
  • Frequency (freq_): The operating frequency of the nodes.
  • Threshold (RXThresh_): The signal reception threshold that defines if a signal can be successfully obtained.

These parameters can be set in the TCL script.

  1. TCL Script to Define Communication Range:

Below is a sample of how to set up these parameters in NS2 and estimate the communication range using the Free Space Propagation Model:

# Create Simulator

set ns [new Simulator]

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

set topo [new Topography]

$topo load_flatgrid 1000 1000

# Create the channel and propagation model

set chan_ [new Channel/WirelessChannel]

set prop_ [new Propagation/FreeSpace]   ;# Use FreeSpace model

set netif_ [new Phy/WirelessPhy]

# Set the propagation model for the simulation

$chan_ set propInstance_ $prop_

# Set node parameters (e.g., power, antenna gains, threshold)

set netif_ [new Phy/WirelessPhy]

$netif_ set Pt_ 0.2818    ;# Transmission power (in Watts)

$netif_ set Gt_ 1.0       ;# Transmit antenna gain

$netif_ set Gr_ 1.0       ;# Receive antenna gain

$netif_ set freq_ 914e6   ;# Operating frequency (e.g., 914 MHz)

$netif_ set L_ 1.0        ;# System loss factor

$netif_ set RXThresh_ 3.652e-10  ;# Reception power threshold

# Create nodes and assign channel

set node_(0) [$ns node]

set node_(1) [$ns node]

$node_(0) set X_ 100

$node_(0) set Y_ 200

$node_(0) set Z_ 0

$node_(1) set X_ 400

$node_(1) set Y_ 200

$node_(1) set Z_ 0

# Set the channel for the nodes

$node_(0) set channel_ $chan_

$node_(1) set channel_ $chan_

# Set up traffic sources and sinks to test communication

  1. Communication Range Calculation:

The communication range can be derived using the Free Space Path Loss model formula:

Pr=Pt⋅Gt⋅Gr⋅λ2(4πd)2LP_r = \frac{P_t \cdot G_t \cdot G_r \cdot \lambda^2}{(4 \pi d)^2 L}Pr​=(4πd)2LPt​⋅Gt​⋅Gr​⋅λ2​

Where:

  • PrP_rPr​ is the acquired power (must be greater than RXThresh_ to successfully receive the signal).
  • PtP_tPt​ is the transmission power.
  • GtG_tGt​ is the gain of the transmitting antenna.
  • GrG_rGr​ is the gain of the receiving antenna.
  • λ\lambdaλ is the wavelength, given by λ=cf\lambda = \frac{c}{f}λ=fc​, where c=3×108c = 3 \times 10^8c=3×108 m/s is the speed of light, and fff is the frequency.
  • ddd is the distance amongst the transmitter and receiver (communication range).
  • LLL is the system loss factor.

You can reorganize this formula to solve for ddd (the communication range):

d=λ4π⋅Pt⋅Gt⋅GrPr⋅Ld = \frac{\lambda}{4 \pi} \cdot \sqrt{\frac{P_t \cdot G_t \cdot G_r}{P_r \cdot L}}d=4πλ​⋅Pr​⋅LPt​⋅Gt​⋅Gr​​​

In the TCL script, you can measure this range for the given parameters.

  1. Example Communication Range Calculation:

Assume the below values from the script:

  • Transmission Power (PtP_tPt​) = 0.2818 Watts
  • Gain (Gt=GrG_t = G_rGt​=Gr​) = 1.0
  • Frequency (fff) = 914 MHz
  • Reception Threshold (RXThresh=PrRXThresh_ = P_rRXThresh=​Pr​) = 3.652×10−103.652 \times 10^{-10}3.652×10−10 Watts
  • System Loss (LLL) = 1.0

Now, calculate the wavelength λ\lambdaλ:

λ=3×108914×106=0.328 meters\lambda = \frac{3 \times 10^8}{914 \times 10^6} = 0.328 \text{ meters}λ=914×1063×108​=0.328 meters

Now, calculate the communication range ddd:

d=0.3284π⋅0.2818×1×13.652×10−10×1d = \frac{0.328}{4 \pi} \cdot \sqrt{\frac{0.2818 \times 1 \times 1}{3.652 \times 10^{-10} \times 1}}d=4π0.328​⋅3.652×10−10×10.2818×1×1​​ d=0.0261⋅0.28183.652×10−10d = 0.0261 \cdot \sqrt{\frac{0.2818}{3.652 \times 10^{-10}}}d=0.0261⋅3.652×10−100.2818​​ d=0.0261⋅7.716×108d = 0.0261 \cdot \sqrt{7.716 \times 10^8}d=0.0261⋅7.716×108​ d=0.0261⋅27774.8d = 0.0261 \cdot 27774.8d=0.0261⋅27774.8 d=724.9 metersd = 724.9 \text{ meters}d=724.9 meters

Thus, the communication range is approximately 725 meters.

  1. Simulating Communication Range in NS2:

Once the range is computed, you can authenticate it in NS2 by placing nodes at changing distances and verifying if communication happens successfully amongst them. If nodes are in the calculated range, communication will happen; otherwise, the packets will be dropped.

# Test communication amongst nodes inside the calculated range

set tcp [new Agent/TCP]

set sink [new Agent/TCPSink]

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

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

$ns connect $tcp $sink

# Create a traffic source

set ftp [new Application/FTP]

$ftp attach-agent $tcp

$ns at 1.0 “$ftp start”

$ns at 5.0 “$ftp stop”

$ns at 10.0 “finish”

  1. Test and Analyze Results:

After the simulation is done, monitor whether the communication is successful when the nodes are positioned inside and away from the communication range. If they are beyond the estimated range, packets will be dropped because of the signal strength falling below the reception threshold.

We have presented the computational steps and methods with examples regarding the calculation of communication range in the ns2 through the above manual. You can estimate the range using three propagation model however in this approach, we used the Free Space Propagation Model including formula.

Determining the communication range in NS2 can be quite challenging. Therefore, we encourage you to remain in contact with us, as we are committed to providing you with optimal guidance. Please share all relevant parameter details, and we assure you of the best possible project outcomes