High-Resolution Multi-Target DOA Estimation for Resonant Beam Systems

Abstract

Direction of arrival (DOA) estimation technology offers a promising solution to address the sensing and positioning demands of Internet of Things (IoT) devices. Optical resonant beam systems (RBS), owing to their inherent characteristics of self-alignment, self-established energy focusing, and passive target sensing, make them naturally suited for {\color{blue}DOA} estimation in IoT scenarios. However, RBS suffer from limited angular resolution and a narrow field of view (FoV) in multi-target environments. To overcome these limitations, this paper proposes a high-resolution wide-field-of-view resonant beam DOA estimation system (RB-HWDOA). The RB-HWDOA integrates an optical spectrum-based DOA estimation algorithm (OSB-DOA), which leverages amplitude information in the two-dimensional Fourier spectrum of the resonant beam, {\color{blue}overcoming the resolution limit imposed by the beam size in spatial-domain methods}. Furthermore, we designed a {\color{blue}telescope} modulation (TM) structure to correct phase and direction mismatches, enabling a multi-Tx framework that focuses beams onto a common sensing module, thereby extending the effective FoV. Combined with the OSB-DOA algorithm, this design supports high-resolution DOA estimation for {\color{blue}multiple targets simultaneously over a wide FoV}. Simulation results show that OSB-DOA resolves angular separations down to $0.1^{\circ}$ across multiple resonant beams, remains robust under noise, {\color{blue}and the TM architecture enables multi-Tx integration for wide-FoV coverage}, making RB-HWDOA a scalable and efficient solution for passive multi-target DOA estimation in complex IoT environments.

Figures (16)

• Figure 1: DOA-based service application scenarios.
• Figure 2: Integrated multi-Tx resonant beam base station (BS) for FoV expansion.
• Figure 3: The architecture of the RB-HWDOA system.
• Figure 4: Functional schematic of the TM structure: (a) optical path illustrating how the TM module corrects the propagation direction of the resonant beam after the retroreflector; (b) definition of the elevation angle $\phi$ and azimuth angle $\theta$. The detailed lens configuration and parameters are given in Fig. 7.
• Figure 5: Schematic diagram of Tx distribution and resonant beam correction, where $f_1$ is the focal length of the retroreflector lens and $f_2$ is the focal length of the last lens of the TM module. The Tx units are distributed on a sphere of radius $f_2$ centered on the sensing module, so that all corrected beams naturally converge at the sphere center for DOA estimation.