AoA-based Position and Orientation Estimation Using Lens MIMO in Cooperative Vehicle-to-Vehicle Systems

Positioning accuracy is a critical requirement for vehicle-to-everything (V2X) use cases. Therefore, this paper derives the theoretical limits of estimation for the position and orientation of vehicles in a cooperative vehicle-to-vehicle (V2V) scenario, using a lens-based multiple-input multiple-output (lens-MIMO) system. Following this, we analyze the Cram$\acute{\text{e}}$r-Rao lower bounds (CRLBs) of the position and orientation estimation and explore a received signal model of a lens-MIMO for the particular angle of arrival (AoA) estimation with a V2V geometric model. Further, we propose a lower complexity AoA estimation technique exploiting the unique characteristics of the lens-MIMO for a single target vehicle; as a result, its estimation scheme is effectively extended by the successive interference cancellation (SIC) method for multiple target vehicles. Given these AoAs, we investigate the lens-MIMO estimation capability for the positions and orientations of vehicles. Subsequently, we prove that the lens-MIMO outperforms a conventional uniform linear array (ULA) in a certain configuration of a lens's structure. Finally, we confirm that the proposed localization algorithm is superior to ULA's CRLB as the resolution of the lens increases in spite of the lower complexity.Comment: 16 pages, 11 figure

A Compact Vertical Scanner for Atomic Force Microscopes

A compact vertical scanner for an atomic force microscope (AFM) is developed. The vertical scanner is designed to have no interference with the optical microscope for viewing the cantilever. The theoretical stiffness and resonance of the scanner are derived and verified via finite element analysis. An optimal design process that maximizes the resonance frequency is performed. To evaluate the scanner’s performance, experiments are performed to evaluate the travel range, resonance frequency, and feedback noise level. In addition, an AFM image using the proposed vertical scanner is generated

Sparse RF Lens Antenna Array Design for AoA Estimation in Wideband Systems: Placement Optimization and Performance Analysis

In this paper, we propose a novel architecture for a lens antenna array (LAA) designed to work with a small number of antennas and enable angle-of-arrival (AoA) estimation for advanced 5G vehicle-to-everything (V2X) use cases that demand wider bandwidths and higher data rates. We derive a received signal in terms of optical analysis to consider the variability of the focal region for different carrier frequencies in a wideband multi-carrier system. By taking full advantage of the beam squint effect for multiple pilot signals with different frequencies, we propose a novel reconfiguration of antenna array (RAA) for the sparse LAA and a max-energy antenna selection (MS) algorithm for the AoA estimation. In addition, this paper presents an analysis of the received power at the single antenna with the maximum energy and compares it to simulation results. In contrast to previous studies on LAA that assumed a large number of antennas, which can require high complexity and hardware costs, the proposed RAA with MS estimation algorithm is shown meets the requirements of 5G V2X in a vehicular environment while utilizing limited RF hardware and has low complexity.Comment: 15 pages, 10 figure

Transjugular insertion of biliary stent in patients with malignant biliary obstruction complicated by ascites with/without coagulopathy: a prospective study of 12 patients

PURPOSEIn patients with malignant biliary obstruction complicated by massive ascites, when endoscopy fails, safe routes for biliary decompression are needed as an alternative to percutaneous approach. We aimed to evaluate the safety and effectiveness of transjugular insertion of biliary stent (TIBS) in patients with malignant biliary obstruction complicated by massive ascites with or without coagulopathy.METHODSFrom March 2012 to December 2017, a total of 12 consecutive patients with malignant biliary obstructions treated with TIBS were enrolled in this study. Five patients had jaundice and cholangitis, while seven had jaundice only. Clinical parameters including technical and clinical success rates and complications following TIBS were evaluated. Overall survival and stent occlusion-free survival were assessed using Kaplan-Meier analysis.RESULTSThe indications for transjugular approach were massive ascites with (n=2) or without (n=10) coagulopathy. TIBS was technically successful in 11 of 12 patients. Clinical success was defined as successful internal drainage and was achieved in eight patients. The mean serum bilirubin level was initially 13.9±6.3 mg/dL and decreased to 4.9±5.3 mg/dL within 1 month after stent placement (P = 0.037). Two patients had procedure-related complications (hemobilia). During the follow-up period (mean, 30 days; range, 1–146 days), all 12 patients died of disease progression. The median overall survival and stent occlusion-free survival times were 19 days (95% confidence interval [CI], 16–22 days) and 19 days (95% CI, 12–26 days), respectively. There was no stent dysfunction in the eight patients that had successful internal drainage.CONCLUSIONTIBS appears to be safe, technically feasible, and clinically effective for patients with malignant biliary obstruction complicated by massive ascites with or without coagulopathy