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How to Implement Filtered OFDM in OMNeT++

To implement the Filtered OFDM in OMNeT++, we have to simulate an advanced multicarrier modulation method that performs refining to each sub-band of an OFDM signal. It improves spectral efficiency and decrease out-of-band emissions, making it appropriate for situations like 5G and beyond. The given procedure will help you to accomplish it.

Steps to Implement Filtered OFDM in OMNeT++

  1. Set Up OMNeT++ Environment:
    • Ensure that OMNeT++ and the INET framework are installed and configured.
    • You might need to extend existing OFDM modules or create custom modules to manage the filtering aspect certain to F-OFDM.
  2. Design the Network Architecture:
    • Generate a network topology containing transmitter and receiver nodes capable of managing OFDM signals.
    • The communication channel should be capable of managing the OFDM signal and rub in the filtering technique to the sub-bands.
  3. Implement the OFDM Modulation:
    • Implement the basic OFDM modulation, where the data is break down into several subcarriers.
    • Each subcarrier is modulated using a conventional scheme like QAM (Quadrature Amplitude Modulation) or PSK (Phase Shift Keying).
  4. Implement Filtering on Sub-Bands:
    • Apply filtering to each sub-band to lower out-of-band emissions. This can be done using techniques like windowing or using particular filter designs (e.g., FIR filters).
    • Make sure that the filtering process is applied after the IFFT (Inverse Fast Fourier Transform) in the OFDM modulation process and before transmission.
  5. Configure the Communication Channel:
    • Configure a communication channel that precisely replicates the transmission of F-OFDM signals, encompassing noise, fading, and other channel impairments.
    • Observe how the filtering enhances spectral efficiency and reduces meddling with adjacent channels.
  6. Implement OFDM Demodulation at the Receiver:
    • The receiver should execute the inverse process: applying the corresponding filters, followed by the FFT (Fast Fourier Transform) to recover the transmitted data from the filtered OFDM signal.
    • Ensure that the receiver exactly demodulates the signal and rebuilding the original data.
  7. Simulate and Monitor Filtered OFDM:
    • Run simulations to monitor the performance of the F-OFDM system. See key metrics like spectral efficiency, bit error rate (BER), and out-of-band emissions.
    • Compare the performance of F-OFDM with conventional OFDM under different scenarios like various channel conditions and sub-band configurations.
  8. Analyze and Visualize Results:
    • Use OMNeT++’s visualization tools to see the spectrum of the transmitted and received signals, focusing on the reduction of out-of-band emissions.
    • Analyze the influence of F-OFDM on network performance containing how it optimize spectral efficiency and reduces interference.

Example Configuration

Here’s an example configuration for implementing Filtered OFDM in OMNeT++:

network = FilteredOFDMNetwork

sim-time-limit = 500s

[Config FilteredOFDMNetwork]

*.numTransmitters = 1

*.numReceivers = 1

# Define the modulation scheme at the transmitter

*.transmitter[0].modulationScheme = “FilteredOFDM”

*.transmitter[0].subcarriers = 256

*.transmitter[0].filterType = “FIR”

*.transmitter[0].filterLength = 64

# Configure the communication channel

*.channel.type = “AWGNChannel”

*.channel.snr = 20dB

*.channel.pathLossExponent = 2.5

# Implement OFDM demodulation with filtering at the receiver

*.receiver[0].demodulationScheme = “FilteredOFDM”

*.receiver[0].subcarriers = 256

*.receiver[0].filterType = “FIR”

*.receiver[0].filterLength = 64

# Enable logging of spectral efficiency and out-of-band emissions

*.transmitter[0].logSpectralEfficiency = true

*.receiver[0].logOutOfBandEmissions = true

Example Scenarios

  1. Scenario 1: Basic Filtered OFDM Transmission
    Implement a scenario where a single transmitter sends data using F-OFDM. Observe how the filtering impacts the out-of-band emissions and compare it with out-dated OFDM transmission.
  2. Scenario 2: Impact of Filter Design on F-OFDM
    Simulate a scenario where several filter designs (e.g., FIR vs. IIR filters) are applied to the sub-bands. Analyze how the select of filter affects spectral efficiency, out-of-band emissions, and BER.
  3. Scenario 3: F-OFDM in a Multi-User Environment
    Implement a scenario where many transmitters use various sub-bands of the spectrum. Use F-OFDM to decrease interruption amongst users and raise overall spectral efficiency. Monitor how well the system performs under different levels of channel congestion.

Considerations:

  • Filter Design: The choice of filter and its parameters (like filter length) can significantly affect the performance of F-OFDM. Experiment with various filter designs to enhance the trade-off amongst spectral efficiency and computational difficulty.
  • Channel Conditions: Examine the F-OFDM system under different channel conditions containing disappearing, intrusion, and noise, to assess its robustness.
  • Comparison with Other Techniques: Associate the performance of F-OFDM with other advanced modulation techniques like FBMC (Filter Bank Multi-Carrier) or UFMC (Universal Filtered Multi-Carrier), to state the best approach for your application.

Through this process, we successfully focused and learned about Filtered OFDM’s installation and implementation in the OMNeT++ and how to use the INET framework to enhance it. If needed, you can modify filter designs in another simulation process to optimize the set up.

If you’re looking for additional thesis topics on Filtered OFDM in OMNeT++, we’re here to offer you implementation support. Please reach out to us for optimal results and performance analysis assistance.