BER Simulation of OFDM System with QPSK Modulation

The OFDM bit error rate simulation program with QPSK modulation includes the following implementation files: 1. comb.m: This file implements signal combination functionality, typically used for merging multiple OFDM subcarriers or combining diversity branches in receiver processing. 2. delay.m: This module introduces signal propagation delays, simulating multipath channel effects by applying time shifts to transmitted signals using delay buffer implementation. 3. fade.m: This file simulates signal fading effects using Rayleigh or Rician fading models, implementing fading coefficient generation and application to simulate wireless channel impairments. 4. giins.m: This module implements guard interval insertion by adding cyclic prefix or zero-padding to OFDM symbols, preventing inter-symbol interference through cyclic extension of OFDM frames. 5. girem.m: This file handles guard interval removal at the receiver side, extracting the valid OFDM symbol portion by discarding the cyclic prefix using precise timing synchronization. 6. ofdm_fading.m: This comprehensive module simulates OFDM signal transmission through fading channels, integrating IFFT/FFT operations with channel modeling to represent complete OFDM system behavior under fading conditions. 7. qpskdemod.m: This file implements QPSK demodulation functionality, converting received complex symbols back to binary data using decision regions and phase detection algorithms. 8. qpskmod.m: This module performs QPSK modulation by mapping input bits to complex constellation points (e.g., ±1±j) using Gray coding for optimal bit error performance. 9. sefade.m: This file calculates the system's bit error rate (BER) by comparing transmitted and received bits, implementing error counting and statistical analysis to evaluate communication system performance. These files collectively form a complete OFDM bit error rate simulation framework with QPSK modulation, enabling researchers to study and analyze QPSK signal performance in OFDM systems under various channel conditions and system parameters.