Bhavani Shankar Mysore Ramarao

Discriminating and locating multiple closely spaced targets in dense environments remains a fundamental challenge for radar sensing, especially in the context of indoor scenarios like smart home or automotive in-cabin applications. Recently, the integration of relatively large aperture metasurface-type reflectors such as FSS or RIS with radar systems was proposed as a promising approach to overcome this limitation. In this work, we present ultra-thin mm-wave absorbers with strong frequency-selective characteristics and we deploy them for integrated tests with a FMCW radar system. By placing the frequency selective absorber (FSA) into the scene, we demonstrate that targets in obscured regions can be successfully detected when operating outside the absorption frequency range. Additionally, using the distinct frequency response, it can help to reveal additional information from the scene, for instance distinguish targets located in line-of-sight (LoS) and non-line-of-sight (NLoS) paths. Several FSA samples are designed and fabricated using screen printing on flexible PET films, i.e., very low-cost processes that enable the creation of large apertures. The experimental characterization includes microscopy and profilometric measurements as well as measurements of the reflection coefficient using a waveguide setup. In the absorption region, a reduction in reflection magnitude is observed down to −30 dB with a −10 dB bandwidth on the order of 1.2 GHz. Bistatic VNA measurements are used to estimate the reflection properties of the FSA under non-normal incident angles, which is important for the deployment. Using a relatively large aperture FSA of the size 430 × 380mm², we can distinguish two targets that appear in the same range but are placed in LoS and NLoS paths, respectively. To this end, two radar sub-bands were defined: one is inside with the FSA’s absorption range and one at frequencies where the FSA is strongly reflective. When switched to the absorption sub-band, the strength of the signal that comes from reflection via the FSA aperture is reduced by about 22.5 dB compared to that in the reflective band.

In this paper, we investigate the massive multipleinput multiple-output (MIMO) radar with few-bit analog-to-digital converters (ADCs) for target detection. In contrast to most of the existing MIMO radar works, where ADCs are considered to be infinite-bit or 1-bit, we propose a general massive MIMO radar system with few-bit (assumed to be B-bit) ADCs whose quantization step can be jointly optimized with the receive filter. For the system under consideration, a comprehensive analysis of radar detection performance is carried out and a new performance metric for MIMO radar with few-bit ADCs, namely, B-bit quantization signal-to-interference-plus-noise ratio (BSINR), is obtained. On this basis, a joint design of the dynamic quantization step and receive filter is formulated and an optimized signal processing technique is derived by devising a two-stage algorithm. Numerous simulations are presented to verify the proposed few-bit detector and performance analysis. Notably, the simulation results also reveal the superiority of adopting few-bit ADCs (especially 3-bit ADCs), which can strike a balance between detection performance and energy efficiency.

Low Earth orbit (LEO) satellite constellations are rapidly becoming essential enablers of next-generation wireless systems, offering global broadband access, high-precision localization, and reliable sensing beyond terrestrial coverage. However, the inherent limitations of individual LEO satellites, including restricted power, limited antenna aperture, and constrained onboard processing, hinder their ability to meet the growing demands of 6G applications. To address these challenges, this article introduces the concept of distributed integrated sensing, localization, and communication (DISLAC) over LEO constellations, inspired by distributed multiple input multiple output architectures. By enabling inter-satellite cooperation through inter-satellite links, DISLAC jointly exploits communication, localization, and sensing functionalities, achieving synergistic gains in throughput, positioning accuracy, and sensing robustness through shared resources and cooperative design. We present illustrative case studies that quantify these benefits and analyze key system-level considerations, including synchronization, antenna reconfigurability, and inter-satellite link design. The article concludes by outlining open research directions to advance the practical deployment of DISLAC in future non-terrestrial networks.