QPSK Modulation and Demodulation with Serial-to-Parallel Conversion, Fourier Transforms, Channel Estimation (LS Criterion), and Doppler Shift

This article provides a detailed exploration of QPSK modulation and demodulation implementation using MATLAB. We will cover key modules including serial-to-parallel conversion, Fourier transforms and inverse transforms, channel estimation based on the Least Squares (LS) criterion, and Doppler shift compensation. Through these modules, readers will gain clear understanding of designing and implementing a complete QPSK modulation and demodulation system. Each module's functionality and integration approach will be explained with MATLAB code examples, such as using fft() and ifft() functions for Fourier transformations, implementing LS estimation through matrix operations for channel compensation, and modeling Doppler effects using frequency shift algorithms. The article will delve into technical details including constellation mapping for QPSK modulation, parallel data processing techniques, and adaptive equalization methods to help readers thoroughly understand the implementation workflow. This comprehensive guide will equip readers with practical knowledge for applying MATLAB in digital communication system design with QPSK modulation schemes.