How to Calculate Network Lifetime in NS2

To implement the Network Lifetime using NS2 normally refers to the duration for which the network can work before a critical node or set of nodes are consumes its energy, particularly in the context of the wireless sensor networks (WSNs) or energy-constrained networks. The lifetime is frequently described as the time up to the first node reduces its energy, while various definitions may use based on the particular application. We follow the below steps that helps to compute the network lifetime in NS2:

Steps to Calculate Network Lifetime in NS2

  1. Simulate with Energy Model

Initially, make certain that energy model is allowed in the NS2 simulation. This model keeps to trace of the energy consumption of each node, containing the transmission, reception, and idle modes.

To permit the energy model, we require to setup it in the TCL script. Here is an sample:

# Create a new node

set ns [new Simulator]

# Set up energy model for each node

set val(chan) Channel/WirelessChannel

set val(prop) Propagation/TwoRayGround

set val(netif) Phy/WirelessPhy

set val(mac) Mac/802_11

set val(ifq) Queue/DropTail/PriQueue

set val(ll) LL

set val(ant) Antenna/OmniAntenna

set val(x) 500 ;# X dimension of the topology

set val(y) 500 ;# Y dimension of the topology

# Energy parameters

set val(initialEnergy) 100.0      ;# Initial energy in Joules

set val(txPower) 0.5              ;# Power consumption for transmission (W)

set val(rxPower) 0.3              ;# Power consumption for reception (W)

set val(idlePower) 0.01           ;# Power consumption when idle (W)

# Create nodes

for {set i 0} {$i < 10} {incr i} {

set node($i) [$ns node]

$node($i) set X_ [expr rand() * $val(x)]

$node($i) set Y_ [expr rand() * $val(y)]

$node($i) set Z_ 0.0

$node($i) add-energy-model $val(initialEnergy) $val(txPower) $val(rxPower) $val(idlePower)

}

In this script:

  • initialEnergy is the starting energy level for each node.
  • txPower, rxPower, and idlePower are signify the power consumed during transmission, reception, and idle states.
  1. Monitor Energy Levels

To estimate the network lifetime, we will want to observe the energy of each node throughout the simulation. It can be done by using a trace file or configure an energy depletion events in the TCL script.

We can periodically verify the remaining energy of each node using the below command:

$node($i) energy

Above command returns the remaining energy of node $i at any given time.

  1. Detect Node Failures

The network lifetime is normally considered the time when the first node exhausts its energy (i.e., the node dies). We can be logged the time at which a node’s energy attains zero by using the below method:

  1. Change the TCL script to verify each node’s energy at regular intervals.
  2. End the simulation when the first node’s energy attains zero.

For example:

proc check-energy {node_id} {

global ns node

set energy_level [$node($node_id) energy]

if { $energy_level <= 0.0 } {

puts “Node $node_id died at time [$ns now]”

$ns halt

} else {

# Continue checking after a short delay

$ns at [expr [$ns now] + 1.0] “check-energy $node_id”

}

}

# Schedule energy checks for each node

for {set i 0} {$i < 10} {incr i} {

$ns at 0.0 “check-energy $i”

}

This script:

  • Verifies the energy level of each node at regular intervals (every second).
  • Prints the time when a node’s energy attains zero and halts the simulation (assuming network lifetime is defined as the time until the first node dies).
  1. Log the Network Lifetime

When the first node dies, the simulation will end and then the time at which this occurs is the network lifetime. We can be computed it by looking at the simulation time using:

$ns now

It gives the recent simulation time in seconds.

  1. Alternative Definitions of Network Lifetime

Based on the research focus, network lifetime can have other definitions:

  • Time until a certain percentage of nodes die: Change the script to stop the replication when a particular percentage of nodes have exhausted their energy.
  • Time until the network becomes disconnected: In this case, the network lifetime is when communication among the nodes is no longer possible because of the energy depletion of key nodes (e.g., relay nodes).

We can be modified the logic in the check-energy process to reflect these definitions.

  1. Analyze the Results

When the simulation is complete then we can be estimated the trace file or the logged output to acquire insights into the network lifetime. It will support in comparing the performance of various protocols or energy management strategies.

Example

If we replicate a wireless sensor network and after running the simulation we monitor that the first node dies at 50 seconds, then the network lifetime is 50 seconds, supposing we are using the “first node death” definition.

Additional Considerations:

  • Energy-efficient protocols: If we are comparing various protocols or routing algorithms (e.g., LEACH, PEGASIS) then we can be repeated the above process for each protocol to observe how it effects the network lifetime.
  • Average network lifetime: We can run numerous simulations and take the average network lifetime to obtain more accurate outcomes.

In this manual, we had given sufficient details and examples are helps to calculate the Network Lifetime, normally refers to duration in NS2 simulation tool. Likewise, we will be offered further comprehensive informations based on your needs. Receive the top project concepts and themes from our staff. Give us all the information about your parameters, and we’ll provide you with the finest support for comparison analysis. Please contact us with any questions you may have about Network Lifetime in NS2 tool projects; we have all the tools available to help.