Jingxian Wu

University of Arkansas at Fayetteville | U of A · Department of Electrical Engineering

PurposePeripheral venous pressure (PVP) waveform analysis is a novel, minimally invasive, and inexpensive method of measuring intravascular volume changes. A porcine cohort was studied to determine how venous and arterial pressure waveforms change due to inhaled and infused anesthetics and acute hemorrhage.Methods Venous and arterial pressure wavef...

Analysis of peripheral venous pressure (PVP) waveforms is a novel method of monitoring intravascular volume. Two pediatric cohorts were studied to test the effect of anesthetic agents on the PVP waveform and cross-talk between peripheral veins and arteries: (1) dehydration setting in a pyloromyotomy using the infused anesthetic propofol and (2) hem...

This paper proposes a supervised multinomial Bayesian learning algorithm for breast cancer detection using terahertz (THz) imaging of freshly excised murine tumors. The proposed algorithm utilizes a multinomial Bayesian probit regression approach, which establishes the link between THz data and classification results by using two different models,...

Purpose: The objective of this study is to quantitatively evaluate terahertz (THz) imaging for differentiating cancerous from non-cancerous tissues in mammary tumors developed in response to injection of N-ethyl-N-nitrosourea (ENU) in Sprague Dawley rats. Approach: While previous studies have investigated the biology of mammary tumors of this model...

We study the problem of determining optimum policy for managing battery energy storage system (BESS) in grid-connected photo-voltaic (PV) systems, where the stochastic electricity demands from the load are met from three sources: grid, PV energy, and BESS. BESS is used either to store excess energy generated from PV systems for later use, or to pur...

We study the sequential quickest change point detection for systems with multiple possible postchange models. A change point is the time instant at which the distribution of a random process changes. In many practical applications, the prechange model can be easily obtained, yet the postchange distribution is unknown due to the unexpected nature of...

Employing massively distributed antennas brings radio access points (RAPs) closer to users, enabling aggressive spectrum reuse that can bridge gaps between the scarce spectrum resource and extremely high connection densities in future wireless systems. Examples include the cloud radio access network (C-RAN), ultradense network (UDN), and cell-free...

Chlorophyll content is an important indicator of the growth status of japonica rice. The objective of this paper is to develop an inversion model that can predict japonica rice chlorophyll content by using hyperspectral image of rice canopy collected with unmanned aerial vehicle (UAV). UAV-based hyperspectral remote sensing can provide timely and c...

This paper proposes an automatic anomaly detection and removal algorithm for peripheral venous pressure (PVP) signals, which can be used to predict intravascular volume loss in humans. PVP signal collection is a minimally invasive procedure that can be performed by using a standard peripheral intravenous (PIV) catheter and a commercial pressure-mon...

Mobile Edge Computing (MEC) is one of the most promising techniques for next-generation wireless communication systems. In this paper, we study the problem of dynamic caching, computation offloading, and resource allocation in cache-assisted multi-user MEC systems with stochastic task arrivals. There are multiple computationally intensive tasks in...

Employing massively distributed antennas brings radio access points (RAPs) closer to users, thus enables aggressive spectrum reuse that can bridge gaps between the scarce spectrum resource and extremely high connection densities in future wireless systems. Examples include cloud radio access network (C-RAN), ultra-dense network (UDN), and cell-free...

https://www.usnc-ursi-archive.org/aps-ursi/2020/pdfs/0000009.pdf

This letter develops an optimum beamforming method for downlink transmissions in cell-free massive multiple-input multiple-output (MIMO) systems, which employ a massive number of distributed access points to provide concurrent services to multiple users. The optimum design is formulated as a max-min problem that maximizes the minimum signal-to-inte...

This letter develops an optimum beamforming method for downlink transmissions in cell-free massive multipleinput multiple-output (MIMO) systems, which employ a massive number of distributed access points to provide concurrent services to multiple users. The optimum design is formulated as a max-min problem that maximizes the minimum signal-tointerf...

Low latency change detection aims to minimize the detection delay of an abrupt change in probability distributions of a random process, subject to certain performance constraints such as the probability of false alarm (PFA). In this paper, we study the low latency detection of bearing faults of direct-drive wind turbines (WT), by analyzing the stat...

Background: In this paper, an unsupervised Bayesian learning method is proposed to perform rice panicle segmentation with optical images taken by unmanned aerial vehicles (UAV) over paddy fields. Unlike existing supervised learning methods that require a large amount of labeled training data, the unsupervised learning approach detects panicle pixe...

The distributed estimation of a spatially correlated random field with decentralized sensor networks is studied in this paper. Nodes in the network take spatial samples of the random field, then each node estimates the values of arbitrary points on the random field by iteratively exchanging information with each other. The objective is to minimize...

A quickest intrusion detection algorithm is proposed to detect false data injection attacks (FDIA) in smart grids with time-varying dynamic models. The quickest detection algorithm aims at minimizing the worst-case detection delays of cyber-attacks, subject to an upper bound of the false alarm rate. Since power grid state transitions could be cause...

The outage probability of an interference-limited linear vehicular ad hoc network (VANET) with random multiple access protocol is studied in this paper. All nodes in the VANET, including the intended transmitter-receiver pair and the interferers, are assumed to form a homogeneous Poisson point process (PPP). Communications between any two nodes in...

We study low latency detections of sparse false data injection attacks in power grids, where an adversary can maliciously manipulate power grid operations by modifying measurements at a small number of smart meters. When a power grid is under attack, the detection delay, which is defined as the time difference between the occurrence and detection o...

This paper studies the fundamental performance limits of a single-input multiple-output (SIMO) high mobility wireless communication systems with imperfect channel state information (CSI). The fundamental limits are quantified in terms of the maximum diversity order (including both Doppler diversity and antenna diversity) that can be achieved by a h...

The optimum designs of multi-hop networks operating in an interference-limited environment are studied in this paper. The objective is to identify the optimum operation parameters that can maximize the end-to-end throughput of a multi-hop link in the network. The optimum designs are performed with respect to two parameters, the number of hops and t...

In this paper, we consider a scenario where an energy harvesting sensor continuously monitors a system and sends time-stamped status updates to a destination. The destination keeps track of the system status through the received updates. We use the metric Age of Information (AoI), the time that has elapsed since the last received update was generat...

In this paper, we study the level set estimation of a spatial-temporally correlated random field by using a small number of spatially distributed sensors. The level sets of a random field are defined as regions where data values exceed a certain threshold. The identification of the boundaries of such sets is an important theoretical problem with a...

In this paper, we study the optimal sensing scheduling problem for an energy harvesting sensor. The objective is to strategically select the sensing time such that the long-term time-average sensing performance is optimized. In the sensing system, it is assumed that the sensing performance depends on the time durations between two consecutive sensi...

Providing reliable broadband wireless communications in high mobility environments, such as high-speed railway systems, remains one of the main challenges faced by the development of the next generation wireless systems. This paper provides a systematic review of high mobility communications. We first summarize a list of key challenges and opportun...

In this paper, we seek answer to the question: can a wireless sensing system with energy harvesting power supplies perform as well as the one with conventional power supplies? Conventional sensing systems with deterministic energy sources usually employ uniform sampling. However, due to the stochastic nature of the energy harvested from the ambient...

A new ultra-low power (ULP) wireless sensor network (WSN) is proposed to monitor the vibration properties of critical structures such as buildings, bridges, and the wings and bodies of aircrafts. The new scheme integrates energy harvesting, data sensing, and wireless communication into a unified process, and it is fundamentally different from all t...

This paper studies energy and spectral efficient Doppler diversity transmissions in the presence of imperfect channel state information (CSI). Fast time-varying fading in high-mobility communication systems introduces Doppler diversity that can benefit system performance. On the other hand, it is more difficult to estimate and track fast time-varyi...

The objective of this paper is to quantify the fundamental tradeoff between Doppler diversity and channel estimation errors in high mobility systems. Fast fading variation in high mobility systems introduces Doppler diversity that can benefit system performance. On the other hand, it is more difficult to estimate and track a fast changing channel,...

Recent research in underwater acoustic communications has taken advantage of MIMO technologies to achieve reliable communication with 10-100 times increase of data rate in comparison to traditional systems. The powerful turbo equalization and FEC coding techniques enable both single-carrier modulation and OFDM systems to combat triply selective UWA...

This paper presents an accurate approximation of the frame error rate (FER) of coded wireless communication systems with receiver diversity. The signals at different diversity branches experience non-independent non-identically distributed Rayleigh fading. The FER approximation is obtained with a threshold-based method. The analytical FER approxima...

This study presents a low-complexity soft-interference cancellation equaliser (SICE) for the turbo detection of multiple-input–multiple-output systems operating in time dispersive channels. The SICE contains three time-invariant linear filters: a feedforward filter, a causal feedback filter and an anti-causal feedback filter. The feedforward filter...

In this paper, we study the optimum transceiver design of multi-user multiple-input multiple-output (MU-MIMO) systems with distributed antennas. The basestation in the system is equipped with multiple distributed antenna units (DAUs) spreading out at different locations in a service area, and they are connected to a central unit (CU) through high-t...

In this paper, we consider a collaborative sensing scenario where sensing nodes are powered by energy harvested from the ambient environment. In each time slot, an active sensor consumes one unit amount of energy to take an observation and transmit it back to a fusion center (FC). After receiving observations from all of the active sensors in a tim...

In this paper, we study the level set estimation of a spatial-temporally correlated random field by using a small number of spatially distributed sensors. The level sets of a random field are defined as regions where data values exceed a certain threshold. We propose a new active sparse sensing and inference scheme, which can accurately extract lev...

This paper studies the theoretical performance of channel estimations in high mobility wireless communication systems operating with doubly-selective (both time-selective and frequency-selective) fading. High mobility communications result in fast time-selective fading with a Doppler spread as high as a few kilo-Hertz. The fast fading variation can...

Level set estimation (LSE) is the process of using noisy observations of an unknown function to estimate the region(s) where the function values lie above a given threshold. It has a wide range of applications in many scientific and engineering areas, such as spectrum sensing or environment monitoring. In this paper, we study the energy-efficient L...

The optimum designs of linear multihop networks that can minimize the end-to-end transmission delays are studied in this paper. In multihop networks, more hops mean a shorter transmission distance per hop but more overheads; thus, it is critical to identify the optimum number of hops that can minimize the end-to-end delay. Two network configuration...

In this paper, we study the optimum estimation of a band-unlimited continuous-time random process using discrete-time samples taken by a sensor powered by energy harvesting devices. In order to accurately represent a band-unlimited random process, a large sampling rate is needed, and this may yield a huge amount of data to be collected and transmit...

The optimum number of hops that can minimize the end-to-end delay of linear multi-hop networks with equidistant relays is studied in this paper. In the network, a source delivers message to its destination by using other nodes as relays. Each hop employs decode-and-forward (DF) with automatic repeat request (ARQ). Two scenarios are considered: one...

In this paper, a low-complexity detection scheme is proposed for an underdetermined multiple-input–multiple-output (UD-MIMO) wireless communication system that employs $N$ transmit antennas and $M < N$ receive antennas. The proposed scheme combines a simplified parallel interference cancelation (S-PIC) with the block decision feedback equalization...

This paper presents an accurate approximation of the frame error rate (FER) of coded wireless communication systems with receiver diversity, such as single-input multiple-output (SIMO) systems with maximum ratio combining (MRC) or hybrid automatic repeat request (HARQ) systems with Chase combining. The signals at different diversity branches experi...

A low complexity detection algorithm based on list sphere decoding (LSD) is proposed for under-determined multiple-input multiple-output (UD-MIMO) systems with N transmit antennas and M <; N receive antennas. The proposed algorithm utilizes the unique structure of UD-MIMO systems by dividing the N detection layers into two groups. Group 1 contains...

This paper studies the maximum Doppler diversity transmissions in the presence of imperfect channel state information (CSI) in high mobility systems. Due to fast time-varying fading in high mobility systems, channel estimation error is usually inevitable and they might have significant impacts on system performance. On the other hand, Doppler sprea...

This paper studies the optimum system designs of high mobility wireless communication systems with channel estimation errors. In high mobility systems, the accurate estimation and tracking of the fast time-varying fading channel is nontrivial, and the residual channel estimation errors might have significant impacts on the system performance. The i...

This paper studies the optimum system design that can maximize the spectral efficiency of high mobility wireless communication systems with imperfect channel state information (CSI). The fast time-varying fading in high mobility systems can be tracked with pilot-assisted channel estimation. The percentage of pilot symbols in the transmitted symbols...

The optimum energy efficient and spectral efficient designs for type-I automatic-repeat-request (ARQ) systems in Rayleigh flat fading channels are studied in this paper. Three optimum designs are considered: the first scheme maximizes the energy efficiency (EE), or equivalently, minimizes the total energy per information bit without considering the...

This paper discusses the energy and spectral efficient transmissions for delay constrained wireless communication systems utilizing hybrid automatic repeat request (HARQ). Three design metrics are considered: 1) the energy efficiency (EE) measured by the average energy required to successfully deliver one information bit from a source to its destin...

A two-stage list sphere decoding (LSD) algorithm is proposed for under-determined multiple-input multiple-output (UD-MIMO) systems that employ N transmit antennas and M < N receive antennas. The two-stage LSD algorithm exploits the unique structure of UD-MIMO systems by dividing the N detection layers into two groups. Group 1 contains layers 1 to M...

This paper presents a low complexity soft-interference cancellation equalizer (SICE) for the turbo detection of multiple-input multiple-output (MIMO) systems operating in time dispersive channels. The SICE contains three time-invariant linear filters: a feedforward filter, a causal feedback filter and an anti-causal feedback filter. The feedforward...

The optimum energy efficient communication of a hybrid automatic repeat request (HARQ) system with Chase combining is studied in this paper. The proposed scheme minimizes the energy required to successfully deliver a bit from a source to its destination by identifying the optimum energy distribution, i.e., the sequence of transmission energy that s...

One of the main challenges faced by communications in high mobility systems, such as unmanned aerial vehicle (UAV), is the fast time-varying fading. This paper studies the optimum system design that can minimize the error probability of a high mobility wireless communication system with imperfect channel state information (CSI). We consider a syste...

In this paper, a frequency-domain cross-layer collision-tolerant (CT) media access control (MAC) scheme is proposed for the up-links of broadband wireless networks with asynchronous users. The collision tolerance is achieved with a frequency-domain on-off accumulative transmission (FD-OOAT) scheme, where the spectrum is divided into a large number...

Due to the current cost of detecting unexploded ordnances (UXOs), alternate systems of detection need to be developed. The Department of Defense views UXO contamination as a high priority problem [1]. The current method of UXO detection involves sweeping an area for UXOs manually with handheld metal detectors. An automated system of detection would...

A new distributed joint source-channel code (DJSCC) is proposed for a communication network with spatial-temporally correlated Markov sources. The DJSCC is performed by puncturing the information bits of a systematic linear block code but leaving the parity bits intact, and transmitting the information and parity bits with unequal energy allocation...

Energy efficiency (EE) and spectral efficiency (SE) feature one of the most fundamental tradeoffs in communication systems. In this paper, we propose an optimum transmission scheme for coded Type-I automatic repeat request (ARQ) systems to balance the EE-SE tradeoff. The optimization is performed with respect to a new design metric, the normalized...

In this paper, a cross-layer collision-tolerant (CT) media access control (MAC) scheme is proposed for wireless networks. Unlike conventional MAC schemes that discard and retransmit signals colliding at a receiver, the CT-MAC extracts the salient information from the colliding signals with a new on-off accumulative transmission (OOAT) scheme in the...

The energy efficient design of coded automatic-repeat-request (ARQ) systems is studied in this paper. The optimization aims to minimize the energy required for the successfully delivery of one information bit from a transmitter to a receiver. The design is performed by incorporating a wide range of practical system parameters and metrics, such as h...

A cross-layer collision-tolerant (CT) media access control (MAC) scheme is proposed in this paper. In the MAC layer, each user transmits multiple weighted replicas of a packet at randomly selected data slots in a frame, and the indices of the selected slots are transmitted in a special collision-free position slot at the beginning of each frame. Co...

A modified FSD algorithm is proposed for under-determined (UD) multiple-input multiple-output (MIMO) systems with N transmit antennas and M < N receive antennas. This paper focuses on the low-complexity detection of coded UD-MIMO systems with iterative turbo detection, where a soft-input soft-output (SISO) MIMO detector exchanges soft information w...

In this paper, a new distributed joint source-channel code (DJSCC) is proposed for a communication network with multiple correlated information sources. The DJSCC is performed by puncturing the information bits of a linear block code but leaving the parity bits intact, given the fact that the correlation among the parity bits is usually much lower...

The optimum sensor node density for one- and two-dimensional (1-D and 2-D) wireless sensor networks (WSNs) with spatial source correlation is studied in this paper. The WSN attempts to reconstruct a spatially correlated signal field by collecting the location-dependent measurements from the distributed sensor nodes. The WSN is designed to minimize...

In this paper, we propose a new cross-layer technique that utilizes frequency-domain on-off accumulative transmission (OOAT) in the physical layer to achieve collision-tolerance in the media access control (MAC) layer. The frequency-domain OOAT is developed for wideband systems operating in frequency-selective fading channels. The available spectru...

This paper presents optimum multi-hop transmission strategies (MHTS) for energy constrained wireless sensor networks (WSNs). Nodes in a multi-hop WSN need to transmit their own information and to relay each other's information to a base station (BS), and there are usually multiple available paths between a node and the BS. The optimum MHTS derived...

A new Slepian-Wolf coded cooperation scheme is proposed for a cognitive radio network with two secondary users (SUs) performing cooperative spectrum sensing through a fusion center (FC). The SUs sense the spectrum by measuring the energy statistics of the received signals. The measured energy statistics are quantized with a Lloyd-Max quantizer at t...

Spectral efficiency is a key characteristic of cellular communications systems, as it quantifies how well the scarce spectrum resource is utilized. It is influenced by the scheduling algorithm as well as the signal and interference statistics, which in turn depend on the propagation characteristics. In this paper we derive analytical expressions fo...

The optimum space and time sampling in a wireless sensor network (WSN) with spatial-temporally correlated data is studied in this paper. The impacts of the node density in the space domain and the sampling rate in the time domain on the network performance are investigated asymptotically by considering a large network with infinite area, infinite t...

Random on-off accumulative transmission (R-OOAT) is a cross-layer technique that can achieve collision-tolerance in the media access control (MAC) layer by leveraging on the signal processing capability in the physical (PHY) layer. In this paper, a new PHY/MAC cross-layer design is proposed for the R-OOAT framework. In the PHY layer, we propose an...

In this paper, a new cooperative spectrum sensing algorithm is proposed for a cognitive radio network with multiple secondary users (SUs) sharing spectrum with one or more primary users (PUs). Unlike most previous spectrum sensing algorithms that do not consider the time domain traffic statistics of the PU, the algorithm in this paper is developed...