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How to Implement Uplink Synchronization in OMNeT++

To implement uplink synchronization in OMNeT++ has encompasses to emulate the process where user equipment (UE) in a cellular network coordinates its transmission timing with the base station (eNodeB in LTE or gNB in 5G). This synchronization is vital to make sure that uplink transmissions from multiple UEs does not strike and that the signals attain at the base station at the correct time. Below are the brief procedures to execute the uplink synchronization in OMNeT++:

Steps to Implement Uplink Synchronization in OMNeT++

  1. Install OMNeT++ and INET Framework:
    • Make sure that OMNeT++ and the INET framework are installed. If we are emulated an LTE or 5G network, incoporate SimuLTE or Simu5G might be helpful.
  2. Define the Network Topology:
    • Generate a network topology using a .ned file that contains the base station (eNodeB/gNB) and multiple UEs. The base station will handle the synchronization process.
  3. Implement Uplink Synchronization Logic:
    • Improve a module that manages uplink synchronization. This module will emulate the process where the base station sends synchronization signals like Timing Advance Command to the UEs, and the UEs regulate their transmission timing respectively.
  4. Configure the Timing Advance Mechanism:
    • Emulate the Timing Advance (TA) mechanism, where UEs adapts their uplink transmission timing based on the distance from the base station. This makes sure that all UEs’ signals arrive at the base station instantaneously.
  5. Handle Transmission Delays:
    • Model transmission delays based on the distance among UEs and the base station. The TA mechanism will reward for these delays to attain synchronization.
  6. Configure Simulation Parameters:
    • Use the .ini file to configure the timing parameters, transmission delays, and other pertinent settings for uplink synchronization.
  7. Run the Simulation and Analyze Results:
    • Run the simulation and assess the efficiency of the uplink synchronization. Key metrics has contain the synchronization accuracy, delay, and how well the UEs’ signals are associated when they reach the base station.

Example: Implementing Uplink Synchronization in OMNeT++

  1. Define the Network Topology in a .ned File

// UplinkSynchronizationNetwork.ned

package networkstructure;

import inet.node.inet.StandardHost;

import inet.node.inet.Router;

network UplinkSynchronizationNetwork

{

submodules:

eNodeB: Router {

@display(“p=250,250”);

numApps = 1;

app[0].typename = “UplinkSynchronizationManager”;

}

ue1: StandardHost {

@display(“p=100,100”);

numApps = 1;

app[0].typename = “UdpBasicApp”;

}

ue2: StandardHost {

@display(“p=400,100”);

numApps = 1;

app[0].typename = “UdpBasicApp”;

}

connections:

ue1.wlan[0] <–> WirelessChannel <–> eNodeB.wlan[0];

ue2.wlan[0] <–> WirelessChannel <–> eNodeB.wlan[1];

}

  1. Implement the Uplink Synchronization Logic

Generate a C++ class for the UplinkSynchronizationManager, which handles the synchronization process.

#include <omnetpp.h>

#include <inet/applications/base/ApplicationBase.h>

using namespace omnetpp;

using namespace inet;

class UplinkSynchronizationManager : public ApplicationBase

{

protected:

virtual void initialize(int stage) override;

virtual void handleMessageWhenUp(cMessage *msg) override;

void sendTimingAdvanceCommand(int ueId, double timingAdvance);

public:

virtual int numInitStages() const override { return NUM_INIT_STAGES; }

};

Define_Module(UplinkSynchronizationManager);

void UplinkSynchronizationManager::initialize(int stage)

{

ApplicationBase::initialize(stage);

if (stage == INITSTAGE_APPLICATION_LAYER) {

// Schedule initial synchronization

scheduleAt(simTime() + 1, new cMessage(“initSync”));

}

}

void UplinkSynchronizationManager::handleMessageWhenUp(cMessage *msg)

{

if (strcmp(msg->getName(), “initSync”) == 0) {

// Example: Calculate timing advance for each UE

double ue1Distance = 150.0; // Example distance to UE1 in meters

double ue2Distance = 300.0; // Example distance to UE2 in meters

// Calculate timing advance (simplified calculation)

double ta1 = ue1Distance / 3.0e8 * 1e6; // Time advance in microseconds

double ta2 = ue2Distance / 3.0e8 * 1e6; // Time advance in microseconds

sendTimingAdvanceCommand(1, ta1);

sendTimingAdvanceCommand(2, ta2);

scheduleAt(simTime() + 1, msg);  // Re-schedule for periodic synchronization

} else {

delete msg;

}

}

void UplinkSynchronizationManager::sendTimingAdvanceCommand(int ueId, double timingAdvance)

{

EV << “Sending Timing Advance Command to UE” << ueId << “: ” << timingAdvance << ” us” << endl;

// Send timing advance command to UE (placeholder for actual implementation)

cMessage *taCommand = new cMessage(“TimingAdvance”);

taCommand->addPar(“timingAdvance”) = timingAdvance;

send(taCommand, “wlan$o”, ueId – 1);  // Send to the corresponding UE

}

  1. Modify Node Modules to Receive Timing Advance Commands

Expand the UE modules to process timing advance commands.

class UplinkSynchronizationUE : public ApplicationBase

{

protected:

virtual void handleMessageWhenUp(cMessage *msg) override;

public:

virtual int numInitStages() const override { return NUM_INIT_STAGES; }

};

Define_Module(UplinkSynchronizationUE);

void UplinkSynchronizationUE::handleMessageWhenUp(cMessage *msg)

{

if (strcmp(msg->getName(), “TimingAdvance”) == 0) {

double timingAdvance = msg->par(“timingAdvance”).doubleValue();

EV << “Received Timing Advance Command: Adjusting transmission timing by ” << timingAdvance << ” us” << endl;

// Adjust UE transmission timing based on the timing advance (placeholder logic)

// Actual implementation would adjust transmission start time

delete msg;

} else {

delete msg;

}

}

  1. Configure the Simulation in the .ini File

network = networkstructure.UplinkSynchronizationNetwork

sim-time-limit = 60s

# Application settings for UEs

**.ue*.app[0].destAddr = “eNodeB”;

**.ue*.app[0].destPort = 1000;

**.ue*.app[0].messageLength = 512B;

**.ue*.app[0].sendInterval = exponential(0.02s);

# Uplink Synchronization settings

**.eNodeB.app[0].timingAdvanceInterval = 1s;  # How often timing advance is sent

  1. Explanation of the Example
  • Network Topology (UplinkSynchronizationNetwork.ned):
    • The network consists of an eNodeB and two UEs (ue1 and ue2), interconnected wirelessly.
    • The eNodeB is responsible for handling the uplink synchronization by sending timing advance commands to the UEs.
  • Uplink Synchronization Manager (UplinkSynchronizationManager.cc):
    • The UplinkSynchronizationManager module computes the timing advance for each UE based on their distance from the base station and transfers a command to adapt their transmission timing.
    • This process is simplified but can be expanded to consider more complex scenarios.
  • UE Processing of Timing Advance (UplinkSynchronizationUE.cc):
    • The UEs receive the timing advance commands and adjust their transmission timing consequently. This makes sure that their uplink signals are synchronized when reaching the base station.
  • Simulation Configuration (omnetpp.ini):
    • The .ini file configures the periodic timing advance intervals and traffic generated by the UEs.

Running the Simulation

  • Compile project in OMNeT++ IDE and run the simulation.
  • To measure how well the UEs synchronize their uplink transmissions and observe the effectiveness of the timing advance mechanism use OMNeT++’s tools.

Extending the Example

  • Dynamic Distance Calculation: Apply dynamic distance calculation based on UE mobility and use it to adapt the timing advance in real-time.
  • More Complex Synchronization: Execute more complex synchronization techniques that consider factors such as signal quality, interference, and UE speed.
  • Handling Multiple UEs: Expand the simulation to manage a larger number of UEs and study the scalability of the synchronization process.
  • Synchronization Accuracy: Execute the parameters to evaluate the accuracy of synchronization and study how various timing advance intervals impact overall network performance.

Here, we clearly understood the basic implementation procedures for uplink synchronization that were securely implemented using the OMNeT++ tool we also outline additional information about how the uplink synchronization performs in diverse simulation tool. omnet-manual.com is ready to assist you as you implement Uplink Synchronization in the OMNeT++ tool. Keep in touch with us to learn more about this topic, and we can also help you with comparison analysis.

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