OFDM Simulation Program with QPSK Modulation

This simulation program implements Orthogonal Frequency Division Multiplexing (OFDM) with Quadrature Phase Shift Keying (QPSK) modulation, incorporating channel encoding/decoding, modulation/demodulation, and up/down sampling processes. The program simulates the complete signal transmission chain by encoding and modulating input signals, transmitting them through a simulated channel, and performing demodulation and decoding for signal recovery. Key algorithmic implementations include convolutional coding for forward error correction, QPSK constellation mapping/demapping with Gray coding, and polyphase filtering techniques for efficient sampling rate conversion. Additional signal processing techniques such as cyclic prefix insertion/removal for OFDM symbol synchronization and pilot-based channel estimation are implemented to enhance signal quality and transmission efficiency under various channel conditions. This simulation provides valuable insights into the practical implementation aspects and performance characteristics of OFDM and QPSK modulation systems.