Performance Enhancement of Photonic-Assisted Distributed MIMO Radar Deployed on a Swarm of Drones

Distributed multiple-input multiple-output (MIMO) radar systems deployed on mobile platforms are gaining strategic importance across a wide range of civil and military applications. These systems offer high sensitivity, robustness to shadowing, and improved target localization capabilities. In recent years, photonic technologies have demonstrated the capability to coherently distribute the radar signals via optical fiber or free-space optical links, thereby enabling the development of coherent distributed radar configurations. This coherence enables effective data fusion and centralized processing from the spatially distributed radars. Thereby, coherent MIMO processing can be achieved across widely separated radars, as in the case of radar mounted on a swarm of drones, where photonic-assisted signal distribution enables precise phase coherence across drones, overcoming RF synchronization limitations in mobile platforms. The design of a distributed MIMO radar system is inherently challenging due to the large number of design parameters involved, especially for mobile sensor platforms. Stepping from our recent experimental demonstrations of coherent photonics-assisted distributed MIMO radar, this paper analyzes the impact of the main system design parameters, i.e., radar signal bandwidth, number of radar peripherals, and baseline geometry and dimension, on the key performance indicators, i.e., spatial resolution and sidelobe levels of the MIMO ambiguity function. It also proposes an innovative approach to improve system performance. This approach aims to minimize hardware complexity by exploiting a combination of meta-heuristic algorithms for architecture optimization and signal post-processing. The former step allows optimization of spatial resolution, while the latter reduces the detrimental effects of sidelobes, which are typical in distributed MIMO radars. The proposed analysis focuses on a specific application of a photonics-assisted radar constellation mounted on a swarm of drones operating in the X and Ka bands. In particular, the proposed optimization method is applied to a 3-transmit/3-receive ( $ 3 \times 3~$ ) MIMO configuration using 3 radar peripherals (RPs), demonstrating the capability to achieve 2 cm resolution in both range and cross-range. The results are validated through MATLAB-based numerical simulations, demonstrating the system’s capability under realistic conditions. The detection capability of the enhanced system is validated when the target is located 50 m away from baseline, using cell-averaging constant false alarm rate detection criterion. A target detection probability of $\textbf {0.996}$ is achieved at false alarm probability of $10^{-6}$ . These results confirm the effectiveness of the proposed approach in enabling high-performance, low-resource drone-based MIMO radar surveillance systems.