Yuhao Wang

A novel low power multifunctional ionospheric sounding system

A novel low power multifunctional ionospheric sounding system, the Wuhan Ionospheric Comprehensive Sounding System (WICSS) is presented. Software Defined Radio (SDR) based and low transmission power are the two most significant features of the system. The system can achieve Vertical-Incidence (VI), oblique backscatter and oblique incidence sounding within low transmitting power. The radar waveforms, system structure and major system parameters are described. Typical experimental results are shown at the end of the paper.

Mechanism and Experiment of Planar Electrode Sensors in Water Pollutant Measurement

This paper investigates the detecting mechanism of planar electrode sensor in water pollutant detection. A system composed of electrodes, bulk media, and electrode-solution interface is built up, and the corresponding equivalent circuit containing bulk and interfacial impedances is established. The influence of each part is discussed while the impedance at interface is especially focused on. The impedance spectroscopy of the circuit is divided into three parts by the cutoff frequencies caused by interfacial and bulk impedances, and each of the frequency range can be used for the measurement of different physical quantities in water. The effect of electrode, especially the combination of interdigital and coils, is analyzed, and nine different sensors were designed and fabricated. Experiments validate the accuracy and validity of the model, and the sensor with best sensitivity is found. The stability of the planar sensor is proven in the experiment too.

Extended Sum-of-Sinusoids-Based Simulation for Rician Fading Channels in Vehicular Ad Hoc Networks

In this paper, we propose an extended reference model and two novel Sum-of-Sinusoids (SoS) models (statistical and deterministic simulation models) propagation models considering the Rician K-factor and vehicle speed ratio in Vehicular Ad Hoc Networks (VANETs). Our models consider comprehensive scene of wave propagation in VANETs, including infrastructure-to-vehicle (I2V) channels with a LOS or NLOS environment, inter-vehicle communication (IVC) channels with a LOS or NLOS environment. The analysis of the statistical properties of the proposed models show that the statistics of the new models match those of the reference model at a large range of normalized time delays. The proposed models show improved approximations to the desired auto-correlation and faster convergence with the increase of Rician K-factor and vehicle speed ratio.

An Experimental Vehicular Wireless System and Link Performance Analysis

Reliable wireless communication is a key component for intelligent transportation systems (ITS). This paper develops a wireless module for ITS using an AR7100 series embedding platform. The module consists of a low-cost multi-interface wireless mesh and control unit to provide high quality of services for different applications. It acts as a node in a vehicular wireless network with a pure software extension without costly hardware modifications. The developed system was tested in the urban area of the Wuhan city, China. It is observed that the fast fading effect plays a significant role in the performance of vehicular communications. To characterize these effects, a physical-level model of the radio link between two moving vehicles is proposed. This model takes the impacts of Rician K-factor, vehicle speed ratio, and Doppler spectrum into consideration. Compared with the existing physical models, the proposed physical-level model is shown to be more accurate in describing the packet-level characteristics of vehicle communications. Furthermore, the analysis of the proposed physical-level model indicates the necessity of cross-layer design of vehicular wireless networks.

Inorganic Material Detection Based on Electrode Sensor

A new method for the detection of an inorganic material with a novel electrode sensor is proposed. Interfacial impedance and water bulk resistance are studied together in a model composed of electrodes, bulk media, and electrode-solution interface. The frequency characteristic is used to measure double layer impedance and water bulk resistance. A planar electrode sensor is designed and fabricated, and the experiment shows that the detectability of ions is clearly enhanced.

Joint Range-Doppler-Angle Estimation for OFDM-Based RadCom System via Tensor Decomposition

Radar and communication (RadCom) systems have received increasing attention due to their high energy efficiency and spectral efficiency. They have been identified as green communications. This paper is concerned with a joint estimation of range-Doppler-angle parameters for an orthogonal frequency division multiplexing (OFDM) based RadCom system. The key idea of the proposed method is to derive different factor matrices by the tensor decomposition method and then extract parameters of the targets from these factor matrices. Different from the classical tensor decomposition method via alternating least squares or higher-order singular value decomposition, we adopt a greedy based method with each step constituted by a rank-1 approximation subproblem. To avoid local extremum, the rank-1 approximation is solved by using a multiple random initialized tensor power method with a comparison procedure followed. A parameterized rectification method is also proposed to incorporate the inherent structures of the factor matrices. The proposed algorithm can estimate all the parameters simultaneously without parameter pairing requirement. The numerical experiments demonstrate superior performance of the proposed algorithm compared with the existing methods.

Sub-THz signals' propagation model in hypersonic plasma sheath under different atmospheric conditions

One of the aims for modern hypersonic cruise flight is hypersonic global reach. The length of route for such flights could be up to thousands of kilometers. The atmospheric conditions on the route are complicated. On the other hand, hypersonic flights used to suffer from communication blackout. The sub-THz communication is considered as a potential solution to the ‘blackout’. In the present study the propagation for sub-THz signals in hypersonic plasma sheaths was modeled under different atmospheric conditions. According to the study, the electron density and the electron collision frequency near the onboard antenna linearly increase with the atmospheric mass density around the vehicle, hence the attenuation of sub-THz signals in hypersonic plasma sheaths increases with the atmospheric mass density. The impact led by the atmospheric temperature is ignorable. Based on the study a new sub-THz signals’ propagation model was developed, which could be utilized for quick estimation for signal propagation under different atmospheric conditions. The geographical difference of signal propagation over the whole globe was obtained with the new model. The results showed that the signal attenuation in plasma sheaths varies with latitude and longitude. The maximum signal attenuation occurs in Alaska, Canada and Russia.

Sparse Representation Based Range-Doppler Processing for Integrated OFDM Radar-Communication Networks

In an integrated radar-communication network, multiuser access techniques with minimal performance degradation and without range-Doppler ambiguities are required, especially in a dense user environment. In this paper, a multiuser access scheme with random subcarrier allocation mechanism is proposed for orthogonal frequency division multiplexing (OFDM) based integrated radar-communication networks. The expression of modulation Symbol-Domain method combined with sparse representation (SR) for range-Doppler estimation is introduced and a parallel reconstruction algorithm is employed. The radar target detection performance is improved with less spectrum occupation. Additionally, a Doppler frequency detector is exploited to decrease the computational complexity. Numerical simulations show that the proposed method outperforms the traditional modulation Symbol-Domain method under ideal and realistic nonideal scenarios.

Distributed Intelligent Monitoring System for Water Environment

As more concern is attached to water environmental protection, the need for continuous water quality monitoring is highlighted. This paper proposes a real-time online water environment monitoring terminal which contains the acquisition, storage, processing and transmission of water environment parameters and control instruction. The sensing part of the terminal includes the novel planar electrode sensor, commercial available sensors, GPS and IP camera. The data acquisition board provides compatible interfaces and stores water quality information. Mesh network is used for transmission. The performance shows the terminal can be effectively applied to distributed water environment automatic monitoring.

The Inversion-based Coverage Prediction Tool for Cellular Networks - Real City Experiments

This work describes a novel tool, called ICPT (inversion-based coverage prediction tool), for predicting coverage field strength in outdoor cellular network by means of the inversion method. Instead of using the high-precision geometric modeling of wireless environments, the problem of radio propagation prediction is solved by using an inversion of the measured data (under all priori constraints), adapting the system parameters according to the change of radio channels and the characteristics of user behaviors. ICPT undertakes the whole process of coverage calculation by loading GIS (Google Earth), selecting the placement of target area and cells with their characterization, and presenting the results in Google Earth. These tasks are easily carried out due to a friendly graphical interface developed in Visual C++2010. The proposed ICPT system is demonstrated using two applications in real city-Zhuhai in China. The results are compared to that obtained by the COST231 model. The system can be used in coverage prediction, network fault diagnosing, as well as automatic drive test.