Tomographic Bistatic 3-D Imaging and Coordinate Reconstruction Method Based on Uplink Communication Process

Integrated sensing and communication (ISAC) is one of the core functions of 6G. Therefore, it is essential to develop sensing and imaging technologies for environmental reconstruction utilizing the existing communication infrastructure. This article proposes a novel tomographic bistatic 3-D imaging and coordinate reconstruction method based on the uplink communication process for the first time. First, this article presents the relationship between the imaging parameters and the communication system and the way to extract echo for imaging from that received by the communication system. Then, a scenario involving base station (BS)-building-user equipment (UE) imaging is proposed, and the model-based principle of the tomographic synthetic aperture radar (TomoSAR) elevation reconstruction is derived. Finally, due to the dense distribution of 6G BSs, different from the traditional spaceborne or airborne systems, the imaging targets are situated in near-field areas. Therefore, the 2-D backprojection (BP) imaging distorts the true spatial location of the targets, leading to differences between the actual positions and the image results. To address this, this article proposes a 3-D coordinate reconstruction algorithm based on BP near-field imaging. The core idea behind this is to transform the 3-D coordinate reconstruction problem into a nonlinear least-squares problem. The simulation experiments demonstrate the effectiveness of the proposed method.