How to Implement Network Energy Harvesting in NS2

To implement the network energy harvesting within NS2 (Network Simulator 2), we require to simulate how nodes can harvest energy from the environmental sources (e.g., solar, wind, or radio frequency) in a network and also use this harvested energy to operate. It is particularly related for Wireless Sensor Networks (WSNs), Internet of Things (IoT) devices, and other low-power networks in which the nodes are battery-powered and it can extend its lifetime by harvesting energy.

Given below is a step-by-step approach to executing energy harvesting in NS2:

Steps to Implement Energy Harvesting in NS2

  1. Understand Energy Harvesting Models

Energy harvesting models are define how much energy a node can harvest over time depends on the environmental conditions. The important factors contain:

  • Energy Source: Solar, wind, or radio frequency (RF) energy.
  • Energy Conversion Efficiency: The rate at which the node transforms environmental energy into the usable power.
  • Energy Storage: The ability of the node’s battery to store harvested energy.
  1. Modify the Node Energy Model

The simulation environment NS2 has already comprises a simple energy model (EnergyModel), which tracks the energy consumption of the nodes. To execute the energy harvesting, we will want to change this model to:

  • Track the Energy Harvested: Append the variables to track the amount of energy harvested over time.
  • Harvest Energy over Time: Execute a mechanism to periodically harvest energy and append it to the node’s energy storage.

Modify EnergyModel Class:

The EnergyModel class (located in energy_model.{cc,h}) wants to be expanded to support energy harvesting.

  • New Variables: Append new variables to the EnergyModel to store metrics related to harvesting, like harvesting rate, energy storage, and the highest battery capacity.

double energy_harvesting_rate;  // Rate of energy harvesting (in Joules per second)

double max_energy_capacity;     // Maximum battery capacity

  • Harvest Energy Function: Execute a function to replicate the energy harvesting over time and renew the node’s energy level.

void EnergyModel::harvestEnergy(double time_interval) {

double harvested_energy = energy_harvesting_rate * time_interval;

if (energy_ + harvested_energy > max_energy_capacity) {

energy_ = max_energy_capacity;

} else {

energy_ += harvested_energy;

}

}

  • Periodically Update the Energy Level: In the key simulation loop, request the harvestEnergy() function periodically to replicate continuous energy harvesting.

void EnergyModel::updateEnergy(double time_interval) {

// Harvest energy at each time interval

harvestEnergy(time_interval);

}

  1. Define Energy Sources and Harvesting Rates

The rate at which energy is harvested based on the source. For instance:

  • Solar Energy: Based on the time of day, weather, and location.
  • RF Energy: Harvested from the ambient radio signals.

We can execute various harvesting models by setting various rates of energy harvesting. For instance, in a basic model, solar energy harvesting may change according to time of the day whereas RF energy harvesting may be constant however at a lower rate.

// Example of time-based solar energy harvesting

double getSolarEnergyHarvestingRate(double current_time) {

if (current_time >= 6.0 && current_time <= 18.0) {  // Daytime

return 0.1;  // High energy harvesting rate

} else {  // Nighttime

return 0.01;  // Low energy harvesting rate

}

}

  1. Modify the Energy Consumption Model

The energy consumption within NS2 is ascertained by the node activities like transmitting, receiving, or idle listening. We may want to adjust or change these consumption model to make certain that it interacts effectively with the energy harvesting mechanism.

Make sure that energy consumption is deducted properly depends on the node activities. We can be modified it in the EnergyModel::DecrTxEnergy() or EnergyModel::DecrRxEnergy() functions to manage the cases in which energy is consumed however also replaced by harvesting.

void EnergyModel::consumeEnergy(double energy_used) {

if (energy_ >= energy_used) {

energy_ -= energy_used;

} else {

// Node has run out of energy

energy_ = 0;

disableNode();  // Function to turn off node when battery is depleted

}

}

  1. Node Sleep and Wake-Up Mechanism

To enhance the energy usage, we can execute a sleep/wake-up mechanism for these nodes. In the energy-constrained networks that nodes are frequently sleep to save energy and wake up only to execute the tasks like sensing or communicating.

  • Sleep Mode: Decrease the energy consumption significantly while the node is idle.
  • Wake-Up Triggers: These nodes can wake up rely on the events such as data reception or sensing intervals.

void Node::sleep() {

// Put the node into sleep mode to save energy

energyModel->consumeEnergy(sleep_energy_rate * sleep_duration);

}

void Node::wakeUp() {

// Wake up the node and resume normal operation

energyModel->consumeEnergy(idle_energy_rate * wake_up_duration);

}

  1. Tcl Script for Energy Harvesting Simulation

In the Tcl simulation script, setup the nodes to use the altered EnergyModel that helps energy harvesting. We can placed various harvesting rates for distinct nodes according to the energy source.

Example Tcl script:

# Create a simulator instance

set ns [new Simulator]

# Create nodes

set node1 [$ns node]

set node2 [$ns node]

# Set up energy model for nodes with energy harvesting

$node1 set energyModel_ [new EnergyModel]

$node2 set energyModel_ [new EnergyModel]

# Set energy harvesting parameters

$node1 set energy_harvesting_rate_ 0.05  ;# Example: Solar energy harvesting rate (J/s)

$node1 set max_energy_capacity_ 1000     ;# Battery capacity in Joules

$node2 set energy_harvesting_rate_ 0.01  ;# Example: RF energy harvesting rate (J/s)

$node2 set max_energy_capacity_ 500      ;# Battery capacity in Joules

# Define a traffic source for nodes

set udp1 [new Agent/UDP]

set udp2 [new Agent/UDP]

$ns attach-agent $node1 $udp1

$ns attach-agent $node2 $udp2

# Create and start traffic

set cbr [new Application/Traffic/CBR]

$cbr attach-agent $udp1

$cbr set packetSize_ 512

$cbr set interval_ 0.01

$ns at 1.0 “$cbr start”

# Run the simulation

$ns run

  1. Performance Evaluation

We can replicate numerous network scenarios and measure, after executing energy harvesting:

  • Node Lifetime: Liken how long nodes are last with and without energy harvesting.
  • Throughput: Compute how energy harvesting impacts the network performance.
  • Energy Consumption and Harvesting: Track the energy consumption and harvested energy for every node.

We can use the simulation tool NS2 trace files to gather the energy-related metrics and also estimate the node lifetime, packet delivery ratio, and throughput under various energy harvesting conditions.

  1. Advanced Features
  • Dynamic Harvesting Models: Execute more furthered models that the energy harvesting rate is alters depending on the dynamic environmental conditions.
  • Energy-Aware Routing: Execute the routing protocols, which take an energy levels into account and use the most energy-efficient routes.
  • Cooperative Harvesting: In the scenarios in which nodes are share energy with each other, execute mechanisms where the nodes are transfer energy to neighbouring nodes.

Ultimately, we discussed above regarding on how to execute and analyse the Network Energy Harvesting and how to modify the energy harvesting model using the stepwise approaches in the simulation platform NS2. More specifies will be presented, if you required.

Contact ns2project.com for personalized implementation assistance with Network Energy Harvesting in NS2 instruction and project ideas. Stay in touch with us to receive the finest implementation help and outcomes. We work on Wireless Sensor Networks (WSNs), Internet of Things (IoT) devices, and other low-power networks realted to your projects.