How to Start OFDM Wireless Communication Projects Using NS2

To stimulate an OFDM (Orthogonal Frequency-Division Multiplexing) Wireless Communication project using NS2 (Network Simulator 2) needs a configuration of replication surroundings which design the physical link layers for wireless communication systems. The NS2 tool does not have native help for OFDM out of the box, nevertheless we can encompass through either executing OFDM models from scratch or using previous extensions.

Here is a step-by-step guide to help you start your OFDM Wireless Communication project using NS2:

Steps to Start OFDM Wireless Communication Projects Using NS2

  1. Install NS2

Previously we start any project, assure that NS2 is installed on your system. If we do not have a installed, follow below these steps:

  • For Linux:

sudo apt-get install ns2

  • For macOS/Windows: We can use a virtual machine or Cygwin to install NS2 for macOS or Windows.

Validate the installation through process a simple sample script such as ns simple.tcl.

  1. Understand OFDM Basics

OFDM is an important method used in several wireless communication standards like Wi-Fi, LTE, and 5G. It split the high-rate data stream into many lower-rate streams that are communicated frequently over the orthogonal subcarriers. Specific main concepts of OFDM:

  • Subcarriers: The subcarriers are narrow-band frequencies used to communicate the data.
  • Cyclic Prefix (CP): Imitate of the final section of OFDM symbol appended to the establishment for mitigate the inter-symbol interference (ISI).
  • Modulation schemes: This scheme includes the several modulation methods like as QPSK, BPSK, or QAM are used on every subcarrier.
  1. Set up OFDM in NS2

The NS2 does not deliver the direct help for OFDM; nevertheless we can use the following methods to model OFDM systems:

  • Custom Implementation: We can apply the OFDM system from scratch using alter the code.
  • Extensions/Existing Modules: Particular study extensions or third-party NS2 design for OFDM exist and can be used. Distinguished the single extension for OFDM Module for NS2 available on GitHub and different other platforms.

Example: OFDM Module for NS2

We can download the OFDM module for NS2 from repositories such as this one or this one.

The component includes the typically:

  • The tools are synchronization.
  • The module is OFDM Modulation/De-modulation.
  • Channel model such as AWGN, Rayleigh, etc.

Once the module is downloaded, follow the installation instructions in the README. This may involve:

  • Extracting the files in the NS2 directory.
  • Re-compiling NS2.
  1. Set up OFDM Topology in NS2

After we have the need to module, you can initialize the configuration of the OFDM network topology NS2.

We will require the describing:

  • Transmitter (OFDM Source): The node which built a data using OFDM modulation for the transmitter.
  • Receiver (OFDM Sink): The receiver node which receives the OFDM signal and demodulates it.
  • Wireless Channel: The wireless channel which models are broadcast for the signal.
  • Mobility Model: Intended for replicating the actions for the nodes (if needed).

Here’s an example of a basic OFDM topology in NS2:

# Create the simulator instance

set ns [new Simulator]

# Create wireless nodes (transmitter and receiver)

set txNode [$ns node]

set rxNode [$ns node]

# Create an OFDM agent for the transmitter node (OFDM source)

set txAgent [new Agent/OFDM]

$ns attach-agent $txNode $txAgent

# Create an OFDM agent for the receiver node (OFDM sink)

set rxAgent [new Agent/OFDM]

$ns attach-agent $rxNode $rxAgent

# Set up wireless channel (e.g., using AWGN or Rayleigh fading)

set channel [new Channel/Wireless]

$ns attach-channel $channel

# Link nodes using a wireless channel

$ns duplex-link $txNode $rxNode 1Mb 20ms DropTail

# Set up traffic generation (e.g., Constant Bit Rate (CBR) traffic)

set cbr [new Application/Traffic/CBR]

$cbr attach-agent $txAgent

$ns at 1.0 “$cbr start”

$ns at 3.0 “$cbr stop”

# Set mobility model (e.g., random waypoint)

$txNode set X_ 10.0

$txNode set Y_ 20.0

$rxNode set X_ 100.0

$rxNode set Y_ 200.0

# Run the simulation

$ns run

Explanation:

  • txNode and rxNode are communicating the receiving nodes for respectively.
  • OFDM Agents: Agent/OFDM characterizes the transmitter and receiver which will use OFDM.
  • The wireless channel for instance Channel/Wireless in which the signal will broadcast.
  • Traffic Generation: The congestion Application/Traffic/CBR creates the frequently data packets from the transmitter.
  • Mobility Model: The simple model is static positioning or arbitrary waypoint mobility can be used.
  1. Modulation and Channel Setup

In OFDM, the modulation and channel surroundings are complex the performance. We may require to:

  • Modulate the Data: Used the data for QPSK, BPSK, or QAM modulation organization for every OFDM subcarrier.
  • Set Channel Models: Channel models used the AWGN (Additive White Gaussian Noise) or Rayleigh fading, that are typical for wireless communication.

For sample, to use a simple AWGN Channel:

# Set up AWGN channel

set chan [new Channel/AWGN]

$ns attach-channel $chan

  1. Cyclic Prefix Handling

In OFDM, the Cyclic Prefix (CP) is increase to improve ISI (Inter-Symbol Interference) due to multipath propagation. The CP maintains often executed in the physical layer for the OFDM system, and particular NS2 extensions for OFDM can include this default.

If not, we can require executing through:

  • Increasing the CP for the data symbol is already communicated.
  • Eliminate the CP at the receiver for previously demodulation.

This is typically maintained through the OFDM Modulation and Demodulation operates, that you will detect the OFDM module.

  1. Traffic and Application Layer

Intended for OFDM replication, we will want to create congestion for follow on how the system behaves below various traffic loads and modulation schemes. General congestion a generator includes they are:

  • Constant Bit Rate (CBR): Used for the constant-rate congestion, this is a basic and useful for validating.
  • FTP or TCP-based traffic: We replicate the real-world file transfer or web browsing congestion.

# Generate TCP traffic from txNode to rxNode

set tcp [new Agent/TCP]

$ns attach-agent $txNode $tcp

set sink [new Agent/TCPSink]

$ns attach-agent $rxNode $sink

  1. Performance Metrics to Measure

After configure the topology and process for the replication, we will need to examine the outcomes. Main performance metrics for OFDM wireless systems includes:

  • Throughput: The throughput data rate achieved through the system.
  • Packet Loss: The rate of packets loss during the transmission.
  • Bit Error Rate (BER): The number of bit errors spit through the total number of transferred bits.
  • Delay: The time takes for the packet we travel from the source to the destination.
  • Signal-to-Noise Ratio (SNR): The ratio for the received signal power to the noise power.

We can examine the parameter metrices using trace files create a replication. NS2 built trace files by packet-level details that can be examined using AWK scripts or XGraph.

To generate trace files:

# Enable trace file generation

set tracefile [open “ofdm_trace.tr” w]

$ns trace-all $tracefile

You can then analyze the trace files using custom scripts or tools.

  1. Run and Visualize the Simulation

After the setting is done, then process for the replication:

ns ofdm_simulation.tcl

The outcomes will be stored in the trace file. We can envision the outcomes using tools such as XGraph or AWK scripts to build a graph for metrics such as throughput, delay, and packet loss.

  1. Extend the Simulation

Next the simple setting, we can encompass the OFDM project through discover the further advanced features:

  • Advanced Channel Models: Execute the fading channels such as Rayleigh, Rician, or Nakagami for beneficial models.
  • OFDM with MIMO: Apply the multiple-input, multiple-output (MIMO) systems to improve the throughput for OFDM by MIMO.
  • Adaptive Modulation and Coding (AMC): Change the modulation schemes according to the channel surroundings for AMC.
  • Interference and Coexistence: Examine the interference from other devices in the similar frequency band.
  • Resource Allocation: Estimate the of power control for scheduling and resource allocation mechanisms.

Conclusion

Initial an OFDM Wireless Communication project in NS2 involves configure a topology which involves the OFDM modulation, a wireless channel, and traffic generation. While NS2 don’t have native help for OFDM, we can use existing modules or implement OFDM functionality yourself. Key concepts to focus on include modulation, cyclic prefix, and wireless channel modeling. Through analyzing the simulation results, you can evaluate the performance of your OFDM system and extend the simulation to explore more advanced concepts.

In the entire page will talk about how OFDM Wireless Communication will perform in the tool of ns2 simulation tool and also we provide the sample snippets, example overview and the future consideration for deploying OFDM Wireless Communication. If you have any query concerning for the OFDM Wireless Communication network we will clarify it.