How to Implement Network Relocation in NS2

To implement the network relocation within NS2 (Network Simulator 2), which refers to actively moving the nodes or modifying the network elements (like base stations or access points) depending on particular conditions like varies in traffic patterns, energy constraints, or node mobility. This method is generally used in vehicular networks (VANETs), wireless sensor networks (WSNs), and mobile ad-hoc networks (MANETs) to enhance the performance, coverage, or energy consumption. If you face any implementation issues the you can contact us we  offer best research guidance.  Given below is a step-by-step technique to executing network relocation in NS2:

Step-by-Step Implementation:

  1. Understand Network Relocation

In the network relocation, these nodes (such as mobile base stations, access points, or mobile sinks) modify their position rely on the dynamic network conditions like:

  • Node mobility: These nodes are move to maintain connectivity.
  • Traffic load: This nodes are relocate to deliver traffic more evenly or prevent the congestion.
  • Energy constraints: Nodes are move to rescue energy or balance energy consumption within the network.
  1. Define Relocation Criteria

Here, we decide the conditions under which the relocation will happen. General criteria contain:

  • Signal strength: These nodes may relocate while the signal strength among them and other nodes are falls below a threshold.
  • Traffic congestion: Nodes are relocate during the traffic at a certain node exceeds a particular threshold.
  • Energy depletion: This nodes are move if their energy levels drop very low.
  • Mobility of nodes: In highly mobile networks that nodes may move to maintain coverage or connectivity.
  1. Modify the Node Mobility Model

The simulation environment NS2 delivers numerous mobility models such as Random Waypoint, Random Walk, and Setdest (set destination) for nodes. To execute the network relocation, we can either use those predefined mobility models or we describe a custom mobility model depends on the relocation criteria.

For example, we can move a node while signal strength falls below a particular threshold, or we can modify its position periodically to balance traffic load.

Example Tcl Script for Relocating a Node Based on Criteria:

In this specimen, a node (such as a mobile base station) relocates rely on the traffic load or signal strength.

# Create a simulator

set ns [new Simulator]

# Create nodes

set node1 [$ns node]

set node2 [$ns node]

# Define the movement for node2 (relocation based on some criteria)

proc relocate_node2 {} {

global ns node2

# Criteria for relocation (e.g., based on signal strength or traffic load)

set load [getTrafficLoad $node2]

if { $load > 10 } {

# Relocate node2 to a new position if the load exceeds threshold

$node2 setdest 100.0 200.0 5.0 ;# Move node2 to (100, 200) at 5 m/s

}

# Schedule the next relocation check

$ns at [expr [$ns now] + 10.0] “relocate_node2”

}

# Start the relocation process at time 1.0 second

$ns at 1.0 “relocate_node2”

# Run the simulation

$ns run

In this sample, the relocate_node2 function verifies the traffic load on the node2 at every 10 seconds then moves it to a new location if the load exceeds a threshold. It can be extended to deliberate other factors such as signal strength or energy levels.

  1. Create a Custom Mobility Model for Relocation

If we require more control across the relocation process, we can make a custom mobility model in C++ class and incorporate it with the Tcl script. This model will actively change the node’s location according to the relocation criteria.

Example of Custom Mobility in C++:

void MobileNode::relocate() {

// Check signal strength or traffic load

double signal_strength = getSignalStrength();

double traffic_load = getTrafficLoad();

// If signal strength is too low or traffic load is too high, relocate the node

if (signal_strength < MIN_SIGNAL_THRESHOLD || traffic_load > MAX_TRAFFIC_LOAD) {

// Set new destination

double new_x = randomDestinationX();

double new_y = randomDestinationY();

set_position(new_x, new_y, 0);  // Move the node to a new position

}

}

In the above code, the relocate() function verifies the present conditions (signal strength or traffic load) then if the conditions warrant relocation, moves the node to a new position. This function can be known periodically when the simulation.

  1. Trigger Relocation Based on Energy Constraints

In energy-constrained networks (like wireless sensor networks) that nodes may relocate while their energy levels are fall below a threshold. We can observe the node’s energy using NS2’s built-in EnergyModel and activate the relocation rely on the node’s remaining energy.

Example of Relocating a Node Based on Energy Levels:

void MobileNode::relocateIfLowEnergy() {

// Check the node’s remaining energy

double remaining_energy = energyModel->energy();

// Relocate if the remaining energy is below a threshold

if (remaining_energy < MIN_ENERGY_THRESHOLD) {

double new_x = randomDestinationX();

double new_y = randomDestinationY();

set_position(new_x, new_y, 0);  // Move the node to a new position

}

}

You can call this function periodically during the simulation to check and adjust the node’s position when the energy level falls below a certain value.

  1. Relocation Due to Traffic Load

These nodes may relocate to manage the traffic congestion or to deliver the network load evenly. We can observe the queue size or traffic throughput at every node then move nodes during the load exceeds a threshold.

Example Tcl Script for Traffic Load-Based Relocation:

# Function to monitor traffic load and relocate the node if necessary

proc monitor_traffic_load {} {

global ns node1

# Get the current traffic load at node1 (example metric)

set load [getTrafficLoad $node1]

# Relocate if the load exceeds a threshold

if { $load > 20 } {

# Move node1 to a new location

$node1 setdest 150.0 250.0 3.0 ;# Relocate to (150, 250) at 3 m/s

}

# Check again after some time

$ns at [expr [$ns now] + 5.0] “monitor_traffic_load”

}

# Schedule the traffic monitoring process to start at time 1.0 second

$ns at 1.0 “monitor_traffic_load”

# Run the simulation

$ns run

  1. Integrating Relocation with Routing

In mobile ad-hoc networks (MANETs) or wireless sensor networks (WSNs) which relocation can be impacted routing decisions. These nodes are require to modernise their routes dynamically while other nodes relocate. We can incorporate the relocation mechanism including the routing protocol (e.g., AODV, DSR) to make certain that routes are updated during nodes change position.

Example (AODV Routing Update on Node Relocation):

void AODV::recvRelocationUpdate(Packet *p) {

struct hdr_ip *ih = HDR_IP(p);

nsaddr_t relocated_node = ih->saddr();

// Update the routing table for the relocated node

rt_entry *rt = rtable.rt_lookup(relocated_node);

if (rt != 0) {

// Invalidate the old route and start route discovery to find the new location

rt->rt_flags = RTF_INVALID;

sendRequest(relocated_node);

}

}

  1. Simulation of Relocation and Performance Evaluation

We can run simulations to estimate the network’s performance, after executing the relocation mechanism. Some important metrics to estimate contain:

  • Throughput: Compute how traffic is managed before and after relocation.
  • Energy consumption: Verify how relocation effects the overall energy efficiency of the network.
  • Packet delivery ratio: Estimate the percentage of effectively delivered packets after nodes are relocate.
  • End-to-end delay: Verify if relocation reduces or increases delay in data delivery.
  1. Sample Tcl Script for Node Relocation Simulation

Below is a basic Tcl script, which executes node relocation depends on the signal strength:

# Create the simulator instance

set ns [new Simulator]

# Create nodes

set node1 [$ns node]

set node2 [$ns node]

# Function to monitor signal strength and relocate node1 if necessary

proc monitor_signal_strength {} {

global ns node1

# Get the current signal strength (example metric)

set signal_strength [getSignalStrength $node1]

# Relocate if signal strength is below a threshold

if { $signal_strength < 10 } {

# Move node1 to a new location

$node1 setdest 200.0 300.0 2.0 ;# Relocate to (200, 300) at 2 m/s

}

# Check again after some time

$ns at [expr [$ns now] + 5.0] “monitor_signal_strength”

}

# Start the relocation monitoring process at time 1.0 second

$ns at 1.0 “monitor_signal_strength”

# Run the simulation

$ns run

Within this module, we provided comprehensive explanation regarding the implement the Network Relocation, integrating relocation and replication of relocation with some sample examples that were executed in NS2. Additional informations regarding this topic will be provided as well.