To simulate a Cellular Topology using OMNeT++ has encompasses configuring a network with several cells, in which each cell is handled by a base station (e.g., a base transceiver station or BTS). For each cell has mobile nodes or user equipment (UE), which connect to the base station that in turn may communicate with other base stations or a central core network.
A cellular topology normally contain:
- Base Stations (BTS/Cell Towers): Responsible for managing communications in their respective cells.
- Mobile Nodes (User Equipment): Mobile devices such as phones or IoT devices, which connect to the base station.
- Core Network: A central entity, which connects the base stations to each other and may offer services like routing, switching, and mobility management.
The following is a common procedure on how we can simulate a Cellular Topology using OMNeT++.
Steps to Simulate Cellular Topology Projects in OMNeT++
- Define the Cellular Network Topology (NED File)
The initial step is to describe the network structure within a NED file. Each base station will connect to numerous mobile nodes, and base stations can be associated to each other through a core network.
Sample NED File (CellularTopology.ned)
network CellularTopology
{
submodules:
// Define the core network that connects base stations
coreNetwork: Node {
@display(“p=300,100”);
}
// Define base stations for multiple cells
baseStation[2]: BaseStation {
@display(“p=200,200; p=400,200”);
}
// Define mobile nodes for each cell
mobileNode1[3]: MobileNode {
@display(“p=150,300; p=200,350; p=250,300”);
}
mobileNode2[3]: MobileNode {
@display(“p=350,300; p=400,350; p=450,300”);
}
connections allowunconnected:
// Connect each mobile node to its corresponding base station
mobileNode1[0].out++ –> baseStation[0].in++;
baseStation[0].out++ –> mobileNode1[0].in++;
mobileNode1[1].out++ –> baseStation[0].in++;
baseStation[0].out++ –> mobileNode1[1].in++;
mobileNode1[2].out++ –> baseStation[0].in++;
baseStation[0].out++ –> mobileNode1[2].in++;
mobileNode2[0].out++ –> baseStation[1].in++;
baseStation[1].out++ –> mobileNode2[0].in++;
mobileNode2[1].out++ –> baseStation[1].in++;
baseStation[1].out++ –> mobileNode2[1].in++;
mobileNode2[2].out++ –> baseStation[1].in++;
baseStation[1].out++ –> mobileNode2[2].in++;
// Connect base stations to the core network
baseStation[0].out++ –> coreNetwork.in++;
coreNetwork.out++ –> baseStation[0].in++;
baseStation[1].out++ –> coreNetwork.in++;
coreNetwork.out++ –> baseStation[1].in++;
}
In this NED file:
- Two base stations (baseStation[0] and baseStation[1]) manage the communications for their corresponding cells.
- Three mobile nodes (mobileNode1[] and mobileNode2[]) are allocated to each base station.
- The core network manages communication among the base stations.
- Define Base Station and Mobile Node Modules (NED Files)
We require to describe the behaviour of both the base stations and mobile nodes. Here’s how we can describe the structure for the base station and mobile nodes.
BaseStation.ned (Base Station Structure)
simple BaseStation
{
parameters:
@display(“i=device/antenna”);
gates:
input in[];
output out[];
}
MobileNode.ned (Mobile Node Structure)
simple MobileNode
{
parameters:
@display(“i=device/phone”);
gates:
input in[];
output out[];
}
- Implement the Node Behavior (C++ Code)
Now, we want to describe the behaviour of both the base stations and mobile nodes. To each mobile node will transmit data to its base station that will either manage the message or forward it to the core network or another base station.
Base Station Behavior (BaseStation.cc)
#include <omnetpp.h>
using namespace omnetpp;
class BaseStation : public cSimpleModule
{
protected:
virtual void initialize() override;
virtual void handleMessage(cMessage *msg) override;
void forwardToCore(cMessage *msg); // Forward the message to the core network
};
Define_Module(BaseStation);
void BaseStation::initialize()
{
// Base stations don’t initiate communication; they wait for mobile node messages.
}
void BaseStation::handleMessage(cMessage *msg)
{
// Process message from mobile node or core network
if (strcmp(msg->getName(), “Message from Mobile”) == 0) {
EV << “Base Station received message from a mobile node.\n”;
forwardToCore(msg); // Forward the message to the core network
} else {
EV << “Base Station received a message from the core network.\n”;
delete msg; // Process or handle core network messages
}
}
void BaseStation::forwardToCore(cMessage *msg)
{
EV << “Base Station forwarding message to the core network.\n”;
send(msg, “out”, 0); // Send to core network
}
Mobile Node Behavior (MobileNode.cc)
#include <omnetpp.h>
using namespace omnetpp;
class MobileNode : public cSimpleModule
{
protected:
virtual void initialize() override;
virtual void handleMessage(cMessage *msg) override;
void sendMessageToBase(); // Send a message to the base station
};
Define_Module(MobileNode);
void MobileNode::initialize()
{
// Schedule the first message to be sent after a short delay
cMessage *msg = new cMessage(“Message from Mobile”);
scheduleAt(simTime() + uniform(1, 5), msg); // Random delay between 1 and 5 seconds
}
void MobileNode::handleMessage(cMessage *msg)
{
// Handle any received messages (could be from the base station)
EV << “Mobile node received a response from the base station.\n”;
delete msg;
}
void MobileNode::sendMessageToBase()
{
// Send a message to the base station
cMessage *msg = new cMessage(“Message from Mobile”);
send(msg, “out”, 0); // Send to the base station
}
In this implementation:
- Mobile nodes initiate communication by transmitting the messages to their corresponding base station.
- Base stations obtain these messages and might forward them to the core network.
- Run the Simulation
Now, we can make an omnetpp.ini file to set up the simulation parameters.
Sample OMNeT++ Configuration (omnetpp.ini)
[General]
network = CellularTopology
sim-time-limit = 20s
# Number of gates for each base station and mobile node
*.baseStation[*].numGates = 4 # Each base station has 3 mobile node connections + 1 core connection
*.mobileNode*.numGates = 1 # Mobile nodes have 1 gate to connect to base station
*.coreNetwork.numGates = 2 # Core network connects to two base stations
- Visualize and Analyze
- Message Flow: We can envision how the mobile nodes are transmit messages to the base stations that forward them to the core network. If needed, we can also replicate message responses from the base stations to the mobile nodes.
- Performance Metrics: We can track parameters like message delays, packet loss, and throughput to investigate the performance of the cellular network.
- Enhancements to the Cellular Simulation
- Handoff Simulation
To mimic handoff (when a mobile node switches from one base station to another), we can dynamically modify the connection of a mobile node to a new base station according to the mobility.
void MobileNode::handleMessage(cMessage *msg)
{
// Implement handoff logic here
if (isMovingToAnotherCell()) {
// Disconnect from current base station and connect to a new one
EV << “Mobile node is switching to a new base station.\n”;
// Implement the reconnection logic here
}
}
- Traffic Load Simulation
We can generate distinct traffic loads by changing the frequency and size of messages are transmitted from the mobile nodes to the base stations.
void MobileNode::initialize()
{
cMessage *msg = new cMessage(“Periodic Message”);
scheduleAt(simTime() + uniform(1, 5), msg); // Random message generation
}
- QoS Metrics (Quality of Service)
We can insert aspects to assess the network performance like latency, jitter, throughput, or packet loss, rely on the messages sent among the mobile nodes and the core network.
- Multiple Cells and Frequency Reuse
We can prolong the simulation by inserting more cells and executing frequency reuse, in which distinct cells are use distinct frequencies to prevent interference while increasing coverage.
- Example Use Case: LTE/5G Cellular Network
This replication can work as the basis for modeling more complex LTE or 5G networks. In such cases, base stations can be substituted with eNodeBs (LTE) or gNodeBs (5G), mobile nodes can be denoted user equipment (UE), and the core network can be prolonged with aspects like mobility management entities (MME) or packet gateways (PG).
These projects focused on how to simulate and analyse the Cellular Topology projects through the simulation process that encompassing enhancements and example cases utilizing OMNeT++ simulation tool. We will share extra details on this topic on your required area with simulation results, if necessary.
phdprime.com will serve as your reliable partner, providing expert guidance for optimal simulation and network evaluation outcomes. We will assist you in simulating cellular topology projects using OMNeT++ with comprehensive support to achieve the best results.
