Nowadays, smart mobile devices include more and more sensors on board, such as motion sensors (accelerometer, gyroscope, magnetometer), wireless signal strength indicators (WiFi, Bluetooth, Zigbee), and visual sensors (LiDAR, camera). People have developed various indoor positioning techniques based on these sensors. In this paper, the probabilistic fusion of multiple sensors is investigated in a hidden Markov model (HMM) framework for mobile-device user-positioning. We propose a graph structure to store the model constructed by multiple sensors during the offline training phase, and a multimodal particle filter to seamlessly fuse the information during the online tracking phase. Based on our algorithm, we develop an indoor positioning system on the iOS platform. The experiments carried out in a typical indoor environment have shown promising results for our proposed algorithm and system design.

This paper introduces a compact Multiple input Multiple output (MIMO) antenna system for vehicular application in the sub-6GHz 5G systems that operates in the middle and high frequency bands from 1.71GHz to 5GHz. The proposed design consists of two symmetrical raised printed monopoles on Flame Retardant 4 (FR4) dielectric material with Partial Ground Plane (PGP) structure to improve bandwidth impedance and achieve higher isolation across the operating frequency range. The design is an excellent candidate to be implement in a shark-fin housing due to its low-profile characteristics and good electrical performance. The antennas are simulated using HFSS software and then prototypes are made and measured on a one-meter rolled-edge ground plane in an anechoic chamber. The electrical performance results of the proposed design and its MIMO characteristics are discussed and plotted in terms of Voltage Standing Wave Ratio (VSWR), passive isolation, radiation patterns, radiation efficiency, linear average gain (LAG), Diversity Gain (DG), and Envelope Correlation Coefficient (ECC).

A cellular 5G sub-6 GHz vehicle antenna design with a consistent radiation pattern across the frequency bands in 0.617–5 GHz is demonstrated via characteristic mode analysis. The design focuses on maintaining monopole first-order mode radiation pattern over cellular frequency bands and avoiding higher-order modes out of the operational frequency bands to provide optimal performance for automotive requirements. Rather than using an empirical design method, the design procedure in this paper uses the calculated modal significance, characteristic current, modal radiation pattern, and reflection coefficient to define the antenna structure dimensions. The proposed design was simulated, a prototype was measured, and the performance was evaluated on a 1-m ground plane. The antenna has perfect omnidirectionality with a high and stable gain across the frequency range in the 30° area above the horizon.

A compact multiband monopole antenna is proposed for vehicular roof top shark-fin applications. The proposed multiband antenna covers 5G sub-6GHz and LTE bands starting at 617MHz to 5000MHz and the higher GNSS band from 1559 to 1606MHz as well as the V2X band at 5900MHz. The presented antenna is a three-dimensional monopole antenna with two branches to cover the required bands with compact size to fit inside a roof top shark-fin. The long antenna branch covers the lower cellular frequency band from 617 to 960MHz, while the short branch covers the higher frequency band from 1559 to 6000MHz. The presented antenna is mounted on a double-sided FR4 PCB and is feeded through a short cable. The proposed antenna covers multiple frequency bands with compact size (H x L x W) of 58×37×17mm³. The antenna is simulated and optimized, and then, a prototype is fabricated, and its radiation characteristics are measured when mounted on one-meter ground plane and on a vehicles roof. The maximum measured linear average gain is 3 dBi at 1900MHz, and the maximum measured efficiency is 88 at 787MHz. The active GNSS antenna gain is measured using an LNA with good isolation. A good agreement is achieved between the simulated and measured results when compared in terms of voltage standing wave ratio (VSWR), radiation patterns, linear average gain (LAG), and antenna efficiency.

This paper presents an analysis of a cellular vehicle-to-everything (C-V2X) quarter-wavelength monopole antenna performance when mounted on full glass roof. Antenna gain measurements performed on a full glass roof exhibited a performance degradation in a linear average gain (LAG) of 8 dB compared to when the same antenna is mounted on a metallic ground plane. In addition, the antenna radiation pattern on the glass roof had deep nulls. Due to a lack of information about the electrical material properties and architecture of the full glass roof sample from the glass supplier for proprietary reasons, a series of gain measurements were performed for the C-V2X monopole when mounted on different glass material samples. The measurement findings suggested the existence of a metal layer in the glass roof sample. Based on this information, the antenna was simulated using a full-wave, three-dimensional electromagnetic field solver on the full glass sample with a low-emissivity (low-E) coating on the edges of the full glass roof. The simulation results showed acceptable agreement with the measurements. A practical solution is suggested to improve the C-V2X antenna performance on the full glass roof. Specific absorption ratio (SAR) analysis is conducted for the passengers in the front and rear seats due to the passenger radiation exposure from the C-V2X monopole antenna mounted on the glass roof. The SAR study showed that the effect of the roof-top C-V2X monopole antenna radiation on the passengers is negligible.