Xingzhong Xiong

Bio: Xingzhong Xiong is an academic researcher from Sichuan University of Science and Engineering. The author has contributed to research in topics: Computer science & Artificial intelligence. The author has an hindex of 4, co-authored 19 publications receiving 57 citations.

Low-Resolution ADCs for Wireless Communication: A Comprehensive Survey

Abstract: With the rapid growth of wireless data traffic and antennas configuration, higher spectrum efficiency and lower power consumption processing have evoked remarkable attention from the research and industry community for the deployment of future wireless communication. It has become a heated topic quickly in recent years and gives rise to the widespread interest around the world. As a core technology of the fifth-generation (5G) mobile communication, massive multi-input multi-output (MIMO) technology can fully exploit the space resources and greatly improve the spectral and energy efficiency. However, massive MIMO systems are faced with the problems of mass data processing, high hardware cost, and huge total power consumption. To cope with these problems, a useful solution is that the receiver equips with finite resolution analog-to-digital (ADC) converters. A large number of research results show that the low-resolution quantization technology brings significant performance within the allowable loss of capacity. This promising technique has attracted many scholars to do tremendous endeavor on it. As a motivation, we make a comprehensive survey about low-resolution ADCs for wireless communication. This paper summarizes the latest developments in the design of low-resolution communication systems, focusing on system performance analysis, some key technologies of the receiver, and typical application scenarios for the low-resolution ADCs. In view of the adverse effects caused by coarse quantization, some potential implementations are presented to alleviate this dilemma. Future research directions are also given and suggested in this paper. This overview contributes significantly to providing an informative and tutorial reference for the key technologies of low-resolution ADCs as well as its applications in practical systems.

Motion Control of Magnetic Microrobot Using Uniform Magnetic Field

Abstract: A microrobot with untethered control in 3D space is a good choice to be applied in the fields of biomedicine with in small and confined workspace. In this paper, an electromagnetic actuation system (EMA) which combined with Helmholtz coil and Maxwell coil for the microrobot 5 DOF locomotion in 3D space is built. The magnetic field analysis of the proposed 3D EMA system was analyzed by finite-element-method (FEM) with multi-physics COMSOL software. The proposed EMA system can produce magnetic field with different characteristics such as a controllable uniform gradient magnetic field, a rotating magnetic field and a oscillating magnetic field in a three-dimensional space by independently changing the current in each coil. In this paper the 3D motion dynamic equation model of microrobot was established. A novel control method for the gravity compensation for the wireless locomotive microrobot was proposed. The proposed method has the property that the direction of magnetic flux and the locomotion path of the microrobot are independent. Meanwhile, it can achieve the horizontal motions or nearly horizontal motions and overcome the gravity well at the same time. It has been verified by experiments in 3D liquid environment. With the proposed method, the microrobot shows good performance in horizontal motions as well as various motions in the 3D space.

Tracking Control of PZT-Driven Compliant Precision Positioning Micromanipulator

Abstract: This paper focuses on improving tracking performance of totally uncoupled compliant micromanipulator based on robust control method of elliptical hysteresis model. The hysteresis model and hysteresis compensation model for proposed mechanism based on Piezoelectric transducer (PZT) are established by using elliptical model method. The values of elliptical hysteresis model parameters are identified by simulating method with different frequencies of control input. The uncertainty model is also established, the values of corresponding estimated parameters are conformed by experiment method. Based on the uncertainty model and elliptical hysteresis model, the robust tracking control method is presented and utilized to evaluate the tracking performance of proposed mechanism under inputting different tracking curves. The proposed method can accurately control the output displacement and improve tracking performance of this mechanism, which are validated and carried out by using experimental studies. Additionally, the coupling errors between two directions are kept within 0.14% and the tracking errors for different curves are within 2.5%.

A New Improved D-S Evidence Theory Based on BJS Divergence in Multi-source Information Fusion

Abstract: Multi-source information fusion is widely used in target recognition. Affected by interference factors, target recognition has great uncertainty. Relevant information cannot be accurately obtained only through a single evidence, which leads to unreliable results of target recognition. Dempster-Shafer (D-S) evidence theory is widely applied in multi-source information fusion due to the advantage of flexibility and effectiveness in combining plenty of uncertain information without prior probabilities. But if there are some high conflict elements in the evidence groups, it will produce some counterintuitive fusion effect, which is worse than before. To solve the above-mentioned problem, a new improved D-S evidence theory based on Belief Jensen-Shannon (BJS) divergence was proposed. We first utilize BJS divergence to locate the evidence groups of which discrepancy exceeds a certain threshold, and the threshold can be set according to the requirements of evidence groups. Subsequently, let the evidence group of which the BJS divergence exceeds the threshold change into the mean value of all the evidence events, this approach can evenly distribute the degree of conflict. Finally, the fusion results can be calculated by the combination rules of D-S evidence theory. Some experiments indicate that this method can get more reasonable results.

Sliding Mode Control: An Incremental Perspective

Abstract: This study focuses on stabilization problem of a class of nonlinear systems. Generally, Lyapunov stability-based sliding mode technique is widely used to design controllers for nonlinear systems with uncertainties. In this paper, however, based on contraction property and sliding surfaces, the sliding mode control is suggested to provide incremental stability for nonlinear systems with uncertainties. The effectiveness of the method is illustrated by numerical simulations.

A Comprehensive Survey on Millimeter Wave Communications for Fifth-Generation Wireless Networks: Feasibility and Challenges

Abstract: Fifth-generation (5G) cellular networks will almost certainly operate in the high-bandwidth, underutilized millimeter-wave (mmWave) frequency spectrum, which offers the potentiality of high-capacity wireless transmission of multi-gigabit-per-second (Gbps) data rates. Despite the enormous available bandwidth potential, mmWave signal transmissions suffer from fundamental technical challenges like severe path loss, sensitivity to blockage, directivity, and narrow beamwidth, due to its short wavelengths. To effectively support system design and deployment, accurate channel modeling comprising several 5G technologies and scenarios is essential. This survey provides a comprehensive overview of several emerging technologies for 5G systems, such as massive multiple-input multiple-output (MIMO) technologies, multiple access technologies, hybrid analog-digital precoding and combining, non-orthogonal multiple access (NOMA), cell-free massive MIMO, and simultaneous wireless information and power transfer (SWIPT) technologies. These technologies induce distinct propagation characteristics and establish specific requirements on 5G channel modeling. To tackle these challenges, we first provide a survey of existing solutions and standards and discuss the radio-frequency (RF) spectrum and regulatory issues for mmWave communications. Second, we compared existing wireless communication techniques like sub-6-GHz WiFi and sub-6 GHz 4G LTE over mmWave communications which come with benefits comprising narrow beam, high signal quality, large capacity data transmission, and strong detection potential. Third, we describe the fundamental propagation characteristics of the mmWave band and survey the existing channel models for mmWave communications. Fourth, we track evolution and advancements in hybrid beamforming for massive MIMO systems in terms of system models of hybrid precoding architectures, hybrid analog and digital precoding/combining matrices, with the potential antenna configuration scenarios and mmWave channel estimation (CE) techniques. Fifth, we extend the scope of the discussion by including multiple access technologies for mmWave systems such as non-orthogonal multiple access (NOMA) and space-division multiple access (SDMA), with limited RF chains at the base station. Lastly, we explore the integration of SWIPT in mmWave massive MIMO systems, with limited RF chains, to realize spectrally and energy-efficient communications.

Neural network motion tracking control of piezo-actuated flexure-based mechanisms for micro-/nanomanipulation

Abstract: This paper presents a neural network motion tracking control methodology for piezo-actuated flexure-based micro-/nanomanipulation mechanisms. In particular, the radial basis function neural networks are adopted for function approximations. The control objective is to track desired motion trajectories in the presence of unknown system parameters, nonlinearities including the hysteresis effect, and external disturbances. In this study, a lumped-parameter dynamic model that combines the piezoelectric actuator and the micro-/nanomechanism is established for the formulation of the proposed approach. The stability of the control methodology is analyzed, and the convergence of the position-and velocity-tracking errors to zero is proven theoretically. A precise tracking performance in following a desired motion trajectory is demonstrated in the experimental study. An important advantage of this control approach is that no prior knowledge is required for not only the system parameters, but also for the thresholds and weights of the neural networks in the physical realization of the control system. This control methodology is very suitable for the implementation of high-performance flexure-based micro-/nanomanipulation control applications.

JCR70: A Low-Complexity Millimeter-Wave Proof-of-Concept Platform for a Fully-Digital SIMO Joint Communication-Radar

Abstract: A fully-digital wideband joint communication-radar (JCR) with a single-input-multiple-output (SIMO) architecture at the millimeter-wave (mmWave) band will enable high joint communication and radar performance with enhanced design flexibility A quantized receiver with few-bit analog-to-digital converters (ADCs) will enable a practical JCR solution with reduced power consumption for futuristic portable devices and autonomous vehicles In this paper, we present a joint communication-radar proof-of-concept platform, named JCR70, to evaluate and demonstrate the performance of these JCR systems using real channel measurements in the 71–76 GHz band We develop this platform by extending a mmWave communication set-up with an additional full-duplex radar receiver and by capturing the SIMO JCR channel using a moving antenna on a sliding rail To characterize the JCR performance of our developed testbed, we conduct several indoor and outdoor experiments and apply traditional as well as advanced processing algorithms on the measured data The experimental results show that the quantized receiver with 2–4 b ADCs generally performs quite close to the high-resolution ADC for a signal-to-noise ratio of up to 5 dB Additionally, we compare the performance of our JCR70 platform with the INRAS Radarbook, which is a state-of-the-art automotive radar evaluation platform at 77 GHz

A Review on the Flexure-Based Displacement Amplification Mechanisms

Abstract: Multifarious flexure-based displacement amplifiers have been proposed and studied in the past decades, showing importance in many industrial fields, such as bioengineering, optical instruments, and semiconductor technology. Displacement amplifiers provide precise motion and large stroke through a simple and low-cost way compared with other piezoelectric actuators. Those merits have opened a door for new and advanced micro devices with unprecedented performance. This paper aims to proffer a comprehensive review on the design, modeling, characteristics, and applications of flexure-based displacement amplifiers, following by pointing out the inherent drawbacks in this research area such as amplification ratio limit, parasitic motion, low lateral stiffness, low natural frequency, and discussing existing solutions and some potential research directions in those topics. Finally, a summary is concluded and the future development perspectives of the displacement amplifiers are discussed. This review contributes to giving a comprehensive understanding of the displacement amplifier, which provides guidance on designing new displacement amplifiers for improving their mechanical output performance. It is also expected to be instrumental for related researchers to understand displacement amplifiers, and to successfully select and design for specific applications.

Design of a Non-Singular Adaptive Integral-Type Finite Time Tracking Control for Nonlinear Systems With External Disturbances

Abstract: This paper proposes an adaptive non-singular fast terminal sliding mode control (FTSMC) with integral surface for the finite time tracking control of nonlinear systems with external disturbances. An appropriate parameter-tuning adaptation law is derived to tackle the disturbances. A new fast terminal sliding scheme with self-tuning algorithm is proposed to synthesize the adaptive non-singular fast integral terminal sliding approach. The proposed approach has the following features: 1) It does not require the derivative of the fractional power terms with respect to time, thereby eschewing the singularity problem typically associated with TSMC; 2) It guarantees the existence of the switching phase under exogenous disturbances with unknown bounds; 3) Because of the integral terms in the sliding surface, the power functions are hidden behind the integrator; 4) It ensures chattering-free dynamics. The effectiveness of the proposed approach is assessed using both a simulation and an experimental study. The obtained results showed that the FTSM control technique guarantees that when the switching surface is reached, tracking errors converge to zero at a fast convergence rate. Additionally, the integral term offers one extra degree-of-freedom and since the time-derivative of fractional power terms is not needed in the controller, the proposed switching surface provides a comprehensive framework for singularity avoidance.