How to Implement Network Dynamic Offloading in NS2

To implement the Network Dynamic Offloading using NS2, which encompasses transmitting the network tasks or computational actively from one node (normally a mobile device) to another node (usually a cloud server or edge server) to enhance the efficiency, minimize latency, or save energy. Offloading decisions can be depend on the network conditions, energy consumption, task size, or processing power. We provide brief approach to execute it in NS2, we require to replicate a network in which the tasks are offloaded rely on particular conditions as well as we want to make or change the protocols, which manage the task offloading.

Additionally,if you need further information on implementing the Network Dynamic Offloading, contact  ns2project.com for additional assistance with your implementation.

Step-by-Step Process to Implement Dynamic Offloading in NS2:

  1. Understand the Dynamic Offloading Requirements:
  • Offloading Decision: The decision to offload a task may rely on the obtainable bandwidth, recent energy levels, processing power, or network latency.
  • Communication Setup: It should be a mechanism to ascertain the communication among the source node (mobile node) and the target node (edge server or cloud).
  • Task Execution and Feedback: When a task is offloaded, feedback or outcomes should be reverted to the source node.
  1. Define the Simulation Topology:
  • Configure a network with mobile nodes, edge servers, or cloud nodes.
  • Mobile nodes should be able to send tasks for offloading according to the particular criteria like low battery, network congestion, or processing load.

Example of an OTcl script to set up the network:

set ns [new Simulator]

set nf [open out.tr w]

$ns trace-all $nf

set namfile [open out.nam w]

$ns namtrace-all $namfile

# Create nodes (mobile node and edge server)

set mobile_node [$ns node]

set edge_server [$ns node]

# Create a duplex link between the mobile node and the edge server

$ns duplex-link $mobile_node $edge_server 1Mb 10ms DropTail

# Define energy and processing capabilities for nodes

$mobile_node set energyModel_ EnergyModel

$mobile_node energyModel setInitialEnergy 1000  ;# Initial energy in Joules

$edge_server set energyModel_ EnergyModel

$edge_server energyModel setInitialEnergy 10000  ;# Higher energy for edge server

# Run the simulation

$ns at 1.0 “start_offloading”

$ns at 5.0 “stop_offloading”

$ns at 6.0 “finish”

proc finish {} {

global ns nf namfile

$ns flush-trace

close $nf

close $namfile

exec nam out.nam &

exit 0

}

$ns run

  1. Modify or Create Offloading Protocol Logic:
  • To execute the dynamic offloading, we require to make a decision-making mechanism to establish when a task should offload. It can be rely on the parameters like:
    • Remaining battery power (on the mobile node)
    • Network latency
    • Processing power (on the edge server)
    • Task size

In the simulation platform NS2, this logic can append as part of the application layer or extended into the routing layer.

Example: Offloading Decision Based on Energy Levels:

  • We can append the logic, which activates the offloading when the energy of the mobile node falls below a threshold.

In the mobile_node C++ class:

void MobileNode::checkEnergyAndOffload(Task* task) {

if (energyModel_->energy() < energy_threshold_) {

// Offload task to edge server

sendTaskToEdge(task);

} else {

// Process locally

processLocally(task);

}

}

void MobileNode::sendTaskToEdge(Task* task) {

Packet* p = new Packet();

hdr_task* hdr = hdr_task::access(p);

hdr->setTask(task);

send(p, edge_server_);

}

void MobileNode::processLocally(Task* task) {

// Simulate local task processing

task->execute();

reportTaskCompletion(task);

}

  • Now, a checkEnergyAndOffload function is known periodically to verify the mobile node’s energy level. If it’s below the threshold then the task is offloaded to the edge server.
  1. Implement Task Communication:
  • We require to describe how tasks are forwarded from the mobile node to the edge server and how the outcomes are communicated back.
  • It can complete by making a new Task packet type and forwarding it as a packet among the nodes.

Define a Task header (e.g., in task.h):

struct hdr_task {

Task* task_;

static int offset_;

inline static hdr_task* access(const Packet* p) {

return (hdr_task*) p->access(offset_);

}

};

Then, implement task managing at the edge server:

void EdgeServer::recv(Packet* p, Handler* h) {

hdr_task* hdr = hdr_task::access(p);

Task* task = hdr->task_;

processTask(task);

sendResultsToMobile(task);

}

void EdgeServer::processTask(Task* task) {

// Simulate task execution on the edge server

task->execute();

}

void EdgeServer::sendResultsToMobile(Task* task) {

Packet* result_packet = new Packet();

hdr_task* result_hdr = hdr_task::access(result_packet);

result_hdr->setTask(task);

send(result_packet, mobile_node_);

}

  1. Define the Offload Decision Process:
  • The decision to offload can be rely on various factors, like:
    • Energy level: Offload when the energy is below a particular threshold.
    • Task size: Offload large tasks, which are computationally intensive.
    • Network conditions: Offload only when the network has sufficient bandwidth or low latency.

Example decision-making logic based on energy and task size:

void MobileNode::checkEnergyAndTaskSize(Task* task) {

if (energyModel_->energy() < energy_threshold_ || task->size() > size_threshold_) {

sendTaskToEdge(task);  // Offload task

} else {

processLocally(task);  // Process locally

}

}

  1. Modify OTcl Script to Trigger Offloading:
  • In the OTcl script, we can request the functions to replicate the task creation also verify for offloading decisions periodically.

Example OTcl commands to start offloading:

proc start_offloading {} {

global mobile_node

# Generate a task on the mobile node and trigger offloading decision

$mobile_node create_task

$mobile_node checkEnergyAndOffload

}

  • It will activate the checkEnergyAndOffload function periodically during the simulation.
  1. Compile and Run the Simulation:
  • After altering the C++ code, recompile NS2 to contain the changes:

make clean

make

  • Run the OTcl script to replicate the dynamic offloading:

ns your_script.tcl

  1. Analyze the Results:
  • Examine the behaviour of the offloading mechanism by observing significant metrics like:
    • Energy consumption: How much energy was saved on the mobile node by offloading tasks.
    • Latency: Calculate the latency launched by offloading.
    • Network usage: Observe the amount of traffic generated among the mobile node and the edge server.
    • Task completion time: Liken the time taken to accomplish the tasks locally against offloading them to the edge server.

We can use the trace files or scripts to extract metrics:

awk ‘{if ($1 == “r” && $4 == “task”) print “Task received at”, $3}’ out.tr

Key Components for Implementation:

  1. Mobile Node and Edge Server: Replicate the nodes are efficient of local task processing and offloading tasks to an edge server.
  2. Offloading Decision Logic: Execute the decision-making rely on energy, network conditions, or task size.
  3. Task Communication: Make a custom packet types to send the tasks among nodes and process them.
  4. Analysis: Gather and estimate the metrics to calculate the behaviour of the offloading mechanism.

Here, we clearly understood the concepts on how to execute and evaluate the Network Dynamic Offloading using the above step-by-step method within NS2 simulation. Furthermore, we will present more specific details, if required.