OFDM-System-Design-and-Analysis

Simulation and analysis of an OFDM communication system using MATLAB and GNU Radio SDR — includes transmitter/receiver design, BER analysis under different PDPs, and FFT size impact on system performance.

Course Project | Jan 2025 – May 2025
Under the guidance of: Dr. Gourab Ghatak
*Department of Electrical Engineering, IIT Delhi

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🧠 Overview

This project focuses on the design, simulation, and analysis of an Orthogonal Frequency Division Multiplexing (OFDM) system using both MATLAB and GNU Radio SDR.
The objective was to study how key parameters — FFT size, Power Delay Profile (PDP), and Cyclic Prefix (CP) — affect system performance, including Bit Error Rate (BER), PAPR, and ISI mitigation.

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⚙️ Implementation Details

🔹 MATLAB Simulation

• Simulated OFDM transmitter and receiver chains with:
  • Modulations: BPSK, QPSK
  • Channel Models: Frequency-selective fading channels with configurablePower Delay Profiles (PDP)
  • Equalization: Pilot-based LS channel estimation and per-subcarrier zero-forcing
• Analyzed:
  • BER vs SNR for different PDPs
  • Effect of FFT size on system robustness
  • Cyclic prefix length on ISI mitigation

🔹 GNU Radio SDR Implementation

• Implemented real-time OFDM transceiver using RTL-SDR.

• Evaluated:

• FFT size impact on channel selectivity and throughput.

• PAPR and spectral efficiency trade-offs

  📊 Results

BER Performance (MATLAB)

PDP	Modulation	Trend
PDP1 (flat)	BPSK / QPSK	Lower BER at high SNR; no ISI
PDP2 (2 taps)	BPSK / QPSK	Moderate fading; BER degradation visible
PDP3 (3 taps)	BPSK / QPSK	Strong multipath → higher BER
Observation	Larger FFT sizes mitigate ISI and reduce BER

PAPR and ISI Analysis (GNU Radio)

• Increasing FFT size increases PAPR but improves frequency selectivity.
• Longer CP improves performance under multipath fading.

Example MATLAB plots: