Simulation of QPSK Modulation and Demodulation in Simulink Model

This Simulink model implements a comprehensive simulation of QPSK (Quadrature Phase Shift Keying) modulation and demodulation. The system generates a baseband signal using square root raised cosine (SRRC) pulse shaping for spectral efficiency, which is then modulated using QPSK techniques. The modulated signal serves as input to the demodulator section where it undergoes coherent detection. Key signal processing stages include matched filtering (using SRRC filters for optimal SNR) and downsampling operations at the detector stage. By adjusting the downsampling phase parameter, users can observe the impact of symbol timing offsets on system performance. The original transmitted symbols are successfully recovered at the detector output.

The model architecture allows for further enhancements through additional functional blocks. Implementation suggestions include: integrating SNR variation blocks (using AWGN channel components) to simulate different channel conditions; incorporating multipath fading models (via Rayleigh/Rician fading blocks) to emulate realistic wireless environments; and extending modulation schemes to higher-order constellations like 16-QAM or 64-QAM (modify constellation mapper/demapper blocks) for increased data rates. These enhancements would enable more thorough performance analysis of QPSK systems under various operational scenarios, including BER calculations using Error Rate Calculation blocks and constellation diagram visualization through scatter plot scopes.