## 2 Related Work
IIR filters are efficient and have a simple optical architecture, but achieving high SNR values in biomedical signal processing remains a challenge. The proposed filter aims to improve the accuracy of FEC signal classification and highlights the importance of filtering out noise in maternal and fetal ECG signals. To further enhance the performance of photonic radar systems, implementing Multiple-Input Multiple-Output (MIMO) technology can be beneficial. MIMO technology allows the system to transmit and receive multiple signals simultaneously by utilizing multiple antennas at both the transmitter and receiver ends. By using multiple antennas, MIMO technology can increase the system's capacity, improve its signal-to-noise ratio, and enhance its resistance to interference and fading. In recent years, the study of MIMO-FSO systems has received extensive attention because of their potential to provide high-speed and dependable communication links over short to medium distances. It can be deducted from the above discussions that IIR filters can be designed to equalize each received signal, enhancing the system's ability to detect and track targets accurately. Combining MIMO with IIR filters in photonic radars can lead to significant improvements in system performance, increasing target detection and tracking capabilities, and better interference and noise mitigation. On the other hand, to detect the multitargets at the same time, mode division multiplexing (MDM) is used. MDM is an advanced technique used in fiber optic communication, where multiple spatial modes of light are used to transmit different data streams through the same optical fiber [20]. MDM significantly increases the data-carrying capacity of optical fibers. This is achieved by exploiting the various modes of light propagation within the fiber, each acting as an independent channel for transmitting data. Unlike Wavelength Division Multiplexing (WDM), which uses different wavelengths (colors) of light, MDM uses different spatial light patterns. This work presents a novel 2 \(\times\) 2 MIMO-based photonic radar system capable of detecting two targets simultaneously in both stationary and non-stationary scenarios, even in the presence of adverse weather conditions. To improve system performance under such conditions, we employed an IIR filter to mitigate the effects of weather-related signal distortion. Our main contributions are highlighted below:  
1. Innovative Integration of Photonic Radar with MIMO and IIR Filter: This paper introduces a novel approach to photonic radar technology by integrating 2 \(\times\) 2 MIMO techniques with an IIR filter. This integration is specifically designed to enhance target detection in turbulent weather conditions, making it a significant contribution to intelligent transportation systems. 2. Homodyne Configuration Utilizing LFMCW Technology: The system operates in a homodyne configuration, employing Linear Frequency Modulated Continuous Wave (LFMCW) technology for high-speed data transmission. This unique configuration uses a single oscillator to generate both signal and reference waveforms, optimizing the system for efficient performance. 3. Mode Division Multiplexing (MDM) for Enhanced Detection Capabilities: The inclusion of mode division multiplexing (MDM) enables the detection and ranging of multiple targets simultaneously, a crucial advancement for operating under adverse atmospheric conditions. This feature significantly improves the system's utility in real-world scenarios. 4. Demonstrated Effectiveness through Numerical Simulations: The effectiveness of the proposed system is demonstrated through extensive numerical simulations. The system exhibits superior performance in terms of range frequency, range resolution, and the detection of moving targets. Notably, the IIR filter significantly enhances the detection capability, achieving a power improvement of 200% for target 1 and 276% for target 2, underlining the practical impact of our research.