GMSK Modulation Implementation with Digital Data Transmission

This example demonstrates digital data transmission using GMSK modulation. The simulation models the complete process of transmitting and receiving random digital data through GMSK modulation. The primary objective of this model is to illustrate the working principles of GSM transmission and reception systems, while also providing BER (Bit Error Rate) measurement capabilities under AWGN channel conditions. GMSK (Gaussian Minimum Shift Keying) is a modulation technique widely used in digital communications. In GMSK implementation, both phase and frequency of the digital signal are modified to enable efficient transmission through bandwidth-limited communication channels. This technique is commonly employed in cellular telephone networks, such as GSM systems. In this model implementation, the digital data first passes through a bandpass filter to eliminate high-frequency noise and unwanted frequency components. The filtered signal then undergoes modulation using a Gaussian filter, which shapes the frequency pulses to maintain constant envelope properties. The modulation process involves integrating the NRZ data with a Gaussian filter response before frequency modulation. At the receiver end, demodulation follows a reverse process using techniques like frequency discrimination or coherent detection to recover the original digital data stream. To evaluate GMSK transmission performance, the model incorporates AWGN (Additive White Gaussian Noise) channel simulation to replicate real-world noise and interference scenarios. The BER measurement subsystem compares transmitted and received bits to quantify modulation efficiency and reliability under various signal-to-noise ratio conditions. This Simulink model provides users with comprehensive insights into digital data transmission fundamentals and practical applications of GMSK modulation in communication systems. Users can explore different transmission scenarios by adjusting key parameters including filter bandwidth-time product, modulation index, and noise power spectral density to analyze system performance under varying channel conditions.