Yuanan Liu

Beijing University of Posts and Telecommunications | BUPT

In this paper, the impact of the intelligent reflecting surface (IRS) on the propagation characteristics is analyzed from the arguments of the physical and electromagnetic characteristics of the channel. Analytical expressions for free-space pathloss are derived based on the terahertz multiple-input multiple-output (MIMO) channel model in different...

The nonlinearity of the trichromatic imaging system response affects the accuracy of reconstructed spectral information. In this paper, an experiment was designed to analyze the nonlinearity affection on spectral reconstruction. The TIFF and sRGB PPM format images were obtained by DCraw software as the linear and nonlinear data, and Gamma transform...

Many studies have demonstrated that augmented reality (AR) learning environments could effectively enhance learning efficiency in formal education compared to real learning environments. Furthermore, multimedia learning in AR has been shown to significantly improve learning performance and reduce cognitive load. However, few studies have explored t...

Most of the existing chromatic adaptation transforms (CATs) were developed for flat uniform stimuli presented in a uniform background, which substantially simplifies the complexity of the real scene by excluding surrounding objects from the viewing field. The impact of the background complexity, in terms of the spatial properties of the objects sur...

In this letter, a power scalable neural network (PSNN) model for wideband digital predistortion (DPD) is proposed. The proposed model extracts the common behavior characteristic of power amplifier (PA) under different input power conditions offline and updates the specific power behavior characteristic online by least-squares (LSs) algorithm. The P...

Antenna pattern measurement generally requires an anechoic chamber with a single ling-of-sight (LOS) propagation. However, it may not be satisfied due to cost and size limitations, leading to a non-anechoic environment (with echoes) and the distorted measured antenna pattern. To address this challenge, this paper proposed an echo suppression method...

The CATs models proposed over these years (such as CMCCAT97, CAT02 and CAT16) were derived from simple stimuli surrounded by a uniform background with a single illuminant. However, the real scene always consists of more than one illumination, especially in many artificially lit environments. Some previous studies indicate an influence of the transi...

Waveguides have become one of the most promising optical combiners for see-through near-eye displays due to the thickness, weight, and transmittance. In this study, we propose a waveguide-type near-eye display using a pin-mirror array and a concaved reflector with a compact outlook, optimized image uniformity and stray light. Issues have been discu...

Massive multiple-input multiple-output (MIMO) is considered as a critical technique in 5 G New Radio (NR), due to its capability to significantly improve data rate and link reliability for the radio link. To make it a reality, it is essential to evaluate massive MIMO performance in realistic spatial fading channel conditions. Specifically, dynamic...

This article presents measurements and simulations of terahertz indoor channels. The measurements are performed in two environments, line‐of‐sight (LoS) and reflected non‐line‐of‐sight (RNLoS). For the LoS environment, the path loss of different distances and the influence of absorbers are investigated. For the RNLoS environment, different material...

This paper presents a novel dual‐band highly efficient power amplifier (PA) design for 5G applications. The presented dual‐band matching network consists of an impedance tuning network and a dual‐band impedance transformer. This structure can not only achieve the precise fundamental and second harmonic control at two 5G bands, but also the excellen...

Two mirror-symmetric dual-branch antennas are closely placed with center to center of 0.34 λ 0 (where λ 0 is the free space wavelength at the resonant frequency, 3.42 GHz). The decoupling structure consists of two decoupling parts, including 1.5 rows of novel miniaturized electromagnetic bandgap (M-EBG) structure and one split on top surface of the...

Measuring the material reflectance of surfaces is a key technology in inverse rendering, which can be used in object appearance reconstruction. In this paper we propose a novel deep learning-based method to extract material information represented by a physically-based bidirectional reflectance distribution function from an RGB image of an object....

A novel memory-grouped method is proposed for digital predistortion (DPD) of power amplifiers (PAs) with constrained acquisition bandwidth (BW) and extremely low sampling rate. By grouping the basis functions with different memory delays, a two-step algorithm can reduce overfitting in the constrained-BW technique. As a result, excellent DPD perform...

Intrinsic decomposition is an inherent problem in computer graphics and computer vision, which decomposes an image into a reflectance image and a shading image. Through the processing of reflectance and shading, it can achieve the image scene editing effect consistent with the vision of the real scene, which endows application potentials to augment...

Virtual and Augmented reality (VR/AR) are widely deployed in industrial, medical, educational, and entertaining fields. The design of interactive interfaces has an impact on usability, comfort, and efficiency. Hand controllers and gestures are popularly used in VR/AR devices. However, users may suffer from overloading on the upper extremities while...

Introducing holographic display methods into near‐eye displays is currently a hot topic to solve vergence accommodation conflict. Due to the etendue conservation, it is hard to achieve a near‐eye display with both a large field of view and a large eye box. Design considerations have been discussed, and these information provide give inspiration to...

Phase-only information derived using a double random-phase encryption (DRPE) algorithm is not visually recognizable but can be authenticated using a nonlinear cross-correlation method. This can be considered to enhance DRPE security (which is vulnerable to a chosen-plaintext attack). Here, we show that phase-only images derived using the DRPE metho...

We developed a new near-eye display measurement system using anthropomorphic vision imaging to measure the key parameters of near-eye displays, including field-of-view (FOV), angular resolution, eye box, and virtual image depth. The characteristics of the human eye, such as pupil position, pupil size variation, accommodation function, and the high...

Three-dimensional information in the real world is observed not only by using the parallax cue created by the different positions of the two eyes, but also by using the depth cue created by adjustment of the crystalline lens. Here we describe a catadioptric light-field camera using two planar mirrors to imitate the process by which humans observe t...

We propose a novel method to construct an optical see-through retinal-projection near-eye display using the Maxwellian view and a holographic method. To provide a dynamic full-color virtual image, a single phase-only spatial light modulator (SLM) was employed in conjunction with a multiplexing-encoding holographic method. Holographic virtual images...

It has always been a hot topic to achieve a near‐eye display with a large field‐of view (FOV) and high‐resolution. Multiple display panels can be employed to break the resolution/FOV invariant in tiling methods and overlapping methods. Several prototypes have also been developed to provide a super‐resolution image with a large field‐of‐view and a h...

Antenna-in-package (AiP) technology has been implemented for millimeter-wave (mmWave) phased array design with antenna elements and radio frequency (RF) chips integrated. The radiation pattern beam of mmWave phased array AiP is typically steered after the in-homogeneous RF branches are aligned (i.e. AiP calibration). The RF branch discrepancies amo...

It is a hot topic to realize high-immersion three-dimensional (3D) virtual reality near-eye displays without the accommodation-convergence conflict. Light-field near-eye display method is considered as one of the most potential solutions to achieve this goal. To obtain virtual image for light-field near-eye displays, many researchers have focused o...

The cover image is based on the Original Article Effects of shading model and opacity on depth perception in optical see-through augmented reality by Jimain Ping et al., https://doi.org/10.1002/jsid.947.

A novel two‐dimensional crest factor reduction (2D‐CFR) is proposed to improve the dual‐band concurrent performance of power amplifiers (PAs). The concurrent performance of target PA can be improved significantly when the power for peak detection conforms to the concurrent characteristic. Peak detection and clipping operation are presented based on...

For significant characteristics such as high efficiency and environmental protection, electric vehicles (EVs) have become a new technology trend in the intelligent transportation system (ITS). Data like real time traffic situation and charge point occupation in ITS shows significant real-time characteristics. Distributed storage system, an effectiv...

Antenna-in-package (AiP) technology has been a main design scheme of millimeter-wave (mmWave) phased array antennas for 5G communications. The beamforming pattern of mmWave phased array AiP is steered by controlling the amplitude and phase excitations of AiP elements. It would be helpful to evaluate the control accuracy of complex excitations and t...

A novel dual-band balanced bandpass filter structure is constructed by utilizing patch resonators and meandered slotlines (MSLs). The center frequencies and passband bandwidths of two differential-mode (DM) passbands can be controlled independently. Specifically, the fractional bandwidth (FBW) in a lower band with the level of S₁₁ better than 15 dB...

The cover image is based on the Research Article Impact on Focal Parameters for Near‐Field‐Focused Aperture Antennas by Weimin Wang, Huaqiang Gao, Yongle Wu, et al., https://doi.org/10.1002/jnm.2510.

Android occupies a very large market share in the field of mobile devices, and quantities of applications are created everyday allowing users to easily use them. However, privacy leaks on Android terminals may result in serious losses to businesses and individuals. Current permission model cannot effectively prevent privacy data leakage. In this pa...

Augmented reality (AR) technologies create an immersive environment by augmenting the real world with rendered virtual objects. One of the key requirements of an AR system is to understand how users perceive the depth of an AR object. Perceived distances to AR objects can be based on various depth cues such as rendering method used for the virtual...

In terms of preventing traffic accidents, improving traffic efficiency, and ensuring personal safety, the research on vehicular ad hoc networks (VANETs) is of great significance. Message authentication is an important security foundation for VANETs. With the rapid growth of the number of access terminals, the existing computing power of the VANETs...

In this paper, a novel concurrent Class B/J continuum mode is presented based on waveform shaping of current and voltage. The behavior characteristics and performances of power amplifiers (PAs) in concurrent dual‐band mode are investigated in detail. According to the analysis of proposed concurrent mode, the optimal load impedances at fundamental,...

Accurate control of complex excitation of array elements is key to ensure spatial discrimination capability of millimeter-wave (mmWave) phased array, e.g. beamforming to target signal directions and nulling towards interference signal directions. Element excitation uncertainties are typically evaluated in an “on-off” mode, where the element under t...

This paper presents a method of reconstructing far-field characteristics by using phaseless spherical near-field measurement, which is used to solve insufficient phase information problem in the near-field measurement of the antenna under test. This method firstly samples the amplitude of two spherical surfaces with different radius in the near-fie...

This paper presents efficient mutual coupling reduction and bandwidth enhancement method in planar monopole multiple antennas. High isolation and bandwidth extension are achieved by integrating a thin inductive line resonator as reflector and parasitic element between the antenna elements. A 36.9% bandwidth (4.69–6.5 GHz) is achieved at 4.9 GHz, wh...

In this article, a multiple‐input‐multiple‐output (MIMO) antenna with high isolation is proposed for ultrawideband (UWB) applications. The proposed MIMO antenna consists of two symmetric slot antenna elements with quasi F‐shaped radiators and L‐shaped open‐slots to increase impedance bandwidth. To improve isolation at the lower band, a decoupling n...

It has always been a hot topic to break the angular resolution/field-of-view (FOV) invariant and achieve a near-eye display with a large FOV and high-resolution. We present a super-resolution method for near-eye displays by overlapping images from two display panels using a half mirror. Key aspects including theoretical analysis, optimized method,...

The virtual reality (VR) and augmented reality (AR) applications have been widely used in a variety of fields; one of the key requirements in a VR or AR system is to understand how users perceive depth in the virtual environment and AR. Three different graphics depth cues are designed in shuffleboard to explore what kind of graphics depth cues are...

Massive multiple-input-multiple-output (MIMO) is known as a large-scale antenna technology and has been enabled for the fifth generation (5G) mobile communication systems. The over-the-air (OTA) testing of massive MIMO antenna system has attracted a lot of attention in terms of evaluating the radio performance of a 5G base station (BS). As a promis...

Light-field near-eye displays can solve the accommodation/convergence conflict problem that can cause severe discomfort to the user. However, in actual systems, convergence depth and accommodation depth may not match each other due to the repeated zones or flipped images produced by traditional light-field methods. Also, Moiré fringes are another p...

In recent years, with the rapid deployment of various Internet of Things(IoT) devices, it becomes a crucial and practical challenge to enable real-time search for objects, data, and services in the Internet of Everything. IoT data prediction model can not only provide solutions for the real-time acquisition of IoT sensor data, but also provide more...

Closed-form design equations and exact numerical examples are presented for the proposed multifunctional rat-race couplers in 1. Correct design parameters and frequency responses are provided for the readers. It is obvious that the four arbitrary terminated impedances of rat-race couplers are completely correct, in despite of whether short (long) e...

Multiple‐input multiple‐output (MIMO) over‐the‐air (OTA) testing is often executed in multi‐probe anechoic chamber (MPAC), the size of which is generally large enough so that the waves radiated from the probes can be considered plane waves in test area. The physical dimension of test setups is a key cost factor. In order to save laboratory space an...