Performance Comparison of Three Modulation Schemes: APSK, PSK, and QAM

This program implements a comprehensive performance comparison of three modulation schemes: APSK (Amplitude Phase Shift Keying), PSK (Phase Shift Keying), and QAM (Quadrature Amplitude Modulation), enhanced with state-of-the-art adaptive predistortion algorithms. The study begins with detailed explanations of the fundamental principles and characteristics of each modulation technique, including constellation diagram configurations and signal space representations. A complete testing framework was designed using MATLAB/Simulink implementations to evaluate performance metrics across various channel conditions, incorporating BER (Bit Error Rate) calculations and spectral efficiency analyses. The adaptive predistortion algorithm dynamically adjusts transmission parameters through real-time channel estimation and digital pre-compensation techniques, utilizing LMS (Least Mean Squares) adaptation for optimal system performance. Experimental results demonstrate that APSK outperforms PSK and QAM in specific channel scenarios (e.g., nonlinear amplifier environments), while PSK or QAM show advantages under different conditions (e.g., AWGN channels). The implementation includes constellation mapping/demapping functions, channel modeling modules, and adaptive filter components with configurable parameters. Based on these findings, conclusions are drawn regarding optimal modulation selection strategies, along with discussions on potential research directions and practical applications in modern communication systems.