Direct Detection OFDM System Based on MATLAB Co-Simulation in VPI

This description elaborates on the specific workflow of implementing a direct detection OFDM system through MATLAB co-simulation in VPI. First, we can specify the exact simulation tools and software versions utilized, such as VPIphotonics Design Suite and MATLAB R2023a with their corresponding interface toolkits. The simulation typically involves parameter configuration through MATLAB scripts, including OFDM modulation parameters like subcarrier count, cyclic prefix length, and QAM modulation order, while VPI handles the optical component modeling including laser characteristics, modulator drive conditions, and photodetector responsivity. The data processing workflow involves generating OFDM symbols in MATLAB using functions like ifft() for inverse Fourier transforms and adding cyclic prefixes, then passing the electrical signal to VPI for optical modulation. The optical transmission simulation includes fiber propagation models with attenuation and dispersion effects, followed by direct detection at the receiver. Key algorithm implementations include constellation mapping/demapping routines, pilot insertion for channel estimation, and bit error rate calculation using comparison functions between transmitted and received data. Simulation inputs consist of baseband data patterns and system parameters, while outputs include eye diagrams, constellation plots, and performance metrics like BER versus received optical power. The relationship between input signal quality, optical link parameters, and output performance can be analyzed through parametric sweeps. Results are evaluated using MATLAB's signal processing toolbox for FFT-based demodulation and statistical analysis functions. Potential enhancements include implementing adaptive equalization algorithms, adding forward error correction coding, or extending to coherent detection schemes by modifying both the MATLAB digital signal processing chain and VPI optical front-end configuration.