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Search Results: 1 - 10 of 44116 matches for " Feng Xia "
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QoS Challenges and Opportunities in Wireless Sensor/Actuator Networks
Feng Xia
Sensors , 2008, DOI: 10.3390/s8021099
Abstract: A wireless sensor/actuator network (WSAN) is a group of sensors and actuators that are geographically distributed and interconnected by wireless networks. Sensors gather information about the state of physical world. Actuators react to this information by performing appropriate actions. WSANs thus enable cyber systems to monitor and manipulate the behavior of the physical world. WSANs are growing at a tremendous pace, just like the exploding evolution of Internet. Supporting quality of service (QoS) will be of critical importance for pervasive WSANs that serve as the network infrastructure of diverse applications. To spark new research and development interests in this field, this paper examines and discusses the requirements, critical challenges, and open research issues on QoS management in WSANs. A brief overview of recent progress is given.
Wireless Sensor Technologies and Applications
Feng Xia
Sensors , 2009, DOI: 10.3390/s91108824
Abstract: Recent years have witnessed tremendous advances in the design and applications of wirelessly networked and embedded sensors. Wireless sensor nodes are typically low-cost, low-power, small devices equipped with limited sensing, data processing and wireless communication capabilities, as well as power supplies. They leverage the concept of wireless sensor networks (WSNs), in which a large (possibly huge) number of collaborative sensor nodes could be deployed. As an outcome of the convergence of micro-electro-mechanical systems (MEMS) technology, wireless communications, and digital electronics, WSNs represent a significant improvement over traditional sensors. In fact, the rapid evolution of WSN technology has accelerated the development and deployment of various novel types of wireless sensors, e.g., multimedia sensors. Fulfilling Moore’s law, wireless sensors are becoming smaller and cheaper, and at the same time more powerful and ubiquitous. [...]
QoS Challenges and Opportunities in Wireless Sensor/Actuator Networks
Feng Xia
Sensors , 2008,
Abstract: A wireless sensor/actuator network (WSAN) is a group of sensors and actuatorsthat are geographically distributed and interconnected by wireless networks. Sensorsgather information about the state of physical world. Actuators react to this information byperforming appropriate actions. WSANs thus enable cyber systems to monitor andmanipulate the behavior of the physical world. WSANs are growing at a tremendous pace,just like the exploding evolution of Internet. Supporting quality of service (QoS) will be ofcritical importance for pervasive WSANs that serve as the network infrastructure ofdiverse applications. To spark new research and development interests in this field, thispaper examines and discusses the requirements, critical challenges, and open researchissues on QoS management in WSANs. A brief overview of recent progress is given.
QoS Challenges and Opportunities in Wireless Sensor/Actuator Networks
Feng Xia
Computer Science , 2008,
Abstract: A wireless sensor/actuator network (WSAN) is a group of sensors and actuators that are geographically distributed and interconnected by wireless networks. Sensors gather information about the state of physical world. Actuators react to this information by performing appropriate actions. WSANs thus enable cyber systems to monitor and manipulate the behavior of the physical world. WSANs are growing at a tremendous pace, just like the exploding evolution of Internet. Supporting quality of service (QoS) will be of critical importance for pervasive WSANs that serve as the network infrastructure of diverse applications. To spark new research and development interests in this field, this paper examines and discusses the requirements, critical challenges, and open research issues on QoS management in WSANs. A brief overview of recent progress is given.
Investigations into the Effect of Spatial Correlation on Channel Estimation and Capacity of Multiple Input Multiple Output System  [PDF]
Xia LIU, Marek E. BIALKOWSKI, Feng WANG
Int'l J. of Communications, Network and System Sciences (IJCNS) , 2009, DOI: 10.4236/ijcns.2009.24029
Abstract: The paper reports on investigations into the effect of spatial correlation on channel estimation and capacity of a multiple input multiple output (MIMO) wireless communication system. Least square (LS), scaled least square (SLS) and minimum mean square error (MMSE) methods are considered for estimating channel properties of a MIMO system using training sequences. The undertaken mathematical analysis reveals that the accuracy of the scaled least square (SLS) and minimum mean square error (MMSE) channel estimation methods are determined by the sum of eigenvalues of the channel correlation matrix. It is shown that for a fixed transmitted power to noise ratio (TPNR) assumed in the training mode, a higher spatial correlation has a positive effect on the performance of SLS and MMSE estimation methods. The effect of accuracy of the estimated Channel State Information (CSI) on MIMO system capacity is illustrated by computer simulations for an uplink case in which only the mobile station (MS) transmitter is surrounded by scattering objects.
A Novel Blind Channel Estimation for a 2x2 MIMO System  [PDF]
Xia LIU, Marek E. BIALKOWSKI, Feng WANG
Int'l J. of Communications, Network and System Sciences (IJCNS) , 2009, DOI: 10.4236/ijcns.2009.25037
Abstract: A novel blind channel estimation method based on a simple coding scheme for a 2 by 2 multiple input multiple output (MIMO) system is described. The proposed algorithm is easy to implement in comparison with conventional blind estimation algorithms, as it is able to recover the channel matrix without performing singular value decomposition (SVD) or eigenvalue decomposition (EVD). The block coding scheme accompanying the proposed estimation approach requires only a block encoder at the transmitter without the need of using the decoder at the receiver. The proposed block coding scheme offers the full coding rate and reduces the noise power to half of its original value. It eliminates the phase ambiguity using only one additional pilot sequence.
Performance of Block Diagonalization Broadcasting Scheme for Multiuser MIMO System Operating in Presence of Spatial Correlation and Mutual Coupling  [PDF]
Feng Wang, Marek E Bialkowski, Xia Liu
Int'l J. of Communications, Network and System Sciences (IJCNS) , 2010, DOI: 10.4236/ijcns.2010.33034
Abstract: In this paper, the capacity of a multiuser Multiple Input Multiple Output (MIMO) system employing the block diagonalization broadcasting scheme in presence of spatial correlation and mutual coupling is investigated. It is shown by computer simulations that, in general, the presence of spatial correlation decreases the capacity of a multiuser MIMO system. However, for some particular antenna element spacing mutual coupling decreases the spatial correlation rendering an increased capacity. The optimized diagonalization broadcasting technique with a two-stage power allocation scheme is proposed and verified. The presented simulations results confirm the advantage of the proposed broadcasting scheme.
Flexible Time-Triggered Sampling in Smart Sensor-Based Wireless Control Systems
Feng Xia,Wenhong Zhao
Sensors , 2007, DOI: 10.3390/s7112548
Abstract: Wireless control systems (WCSs) often have to operate in dynamic environmentswhere the network traffic load may vary unpredictably over time. The sampling in sensors isconventionally time triggered with fixed periods. In this context, only worse-than-possiblequality of control (QoC) can be achieved when the network is underloaded, whileoverloaded conditions may significantly degrade the QoC, even causing system instability.This is particularly true when the bandwidth of the wireless network is limited and sharedby multiple control loops. To address these problems, a flexible time-triggered samplingscheme is presented in this work. Smart sensors are used to facilitate dynamic adjustment ofsampling periods, which enhances the flexibility and resource efficiency of the system basedon time-triggered sampling. Feedback control technology is exploited for adapting samplingperiods in a periodic manner. The deadline miss ratio in each control loop is maintainedat/around a desired level, regardless of workload variations. Simulation results show that theproposed sampling scheme is able to deal with dynamic and unpredictable variations innetwork traffic load. Compared to conventional time-triggered sampling, it leads to muchbetter QoC in WCSs operating in dynamic environments.
Dimethylammonium 2-[(2-oxo-2H-chromen-7-yl)oxy]acetate
Feng-Xia Dong
Acta Crystallographica Section E , 2011, DOI: 10.1107/s1600536811012761
Abstract: In the title salt, C2H8N+·C11H7O5 , the acetate group is twisted out of the plane of the coumarin ring system with a C—O—C—C torsion angle of 76.3 (2)°. In the crystal, N—H...O hydrogen bonds link the cations and anions into chains propagating in [100].
Guest Editorial
Xianchao Zhang,Feng Xia
Journal of Software , 2011, DOI: 10.4304/jsw.6.12.2329-2330
Abstract: As an exponentially increasing amount of data is generated everyday, parallel and distributed data processing has emerged as a key enabling technology and plays more and more important roles in modern computing and information technologies. In recent years, many researchers have become increasingly interested in the field of parallel and distributed data processing, and a large number of remarkable academic achievements have been published and applied to various domains. In this special issue, we selected some excellent papers from the third International Symposium on Parallel Architectures, Algorithms and Programming (PAAP 2010), which was held in Dalian, China, December 18-20, 2010. In addition, we invited and selected some representative research papers in the broad area of parallel and distributed data processing. The paper titled "A Translation Framework for Executing the Sequential Binary Code on CPU/GPU Based Architectures" proposes a novel translation framework for constructing the virtual execution environment aiming at accelerating the process of DBT on CPU/GPU based architectures. With parallelizable parts (hot spots) of binary code and their related information, the framework converts the sequential code into PTX form and executes them on GPUs. The paper titled "A Dynamic-Static Combined Code Layout Reorganization Approach for Dynamic Binary Translation" presents a dynamic-static combined approach to reorganize the layout of software cache. Under this approach, we first employ an emulating execution to collect the profile information and the translated target code. The paper titled "An Efficient Hybrid Clustering-PSO Algorithm for Anomaly Intrusion Detection" demonstrates IDCPSO algorithm, which combines an unsupervised clustering algorithm with the PSO technique to optimize the clustering results and obtain the optimal detection result with unlabeled data. The paper titled "A Hybrid Method for XML Clustering by Structure and Content" presents an effective XML cluster method based both structural similarity calculated using method PFWLCS with position frequency weight, based on frequency path model, and content information contained in XML files. The paper titled "Hybrid Distributed Shared Memory Space in Multi-core Processors" observes that it is unnecessary to perform V2P address translation for private data accesses and introduces hybrid DSM organization and run-time partitioning technique in order to improve the system performance by reducing V2P address translation overhead as much as possible. The paper titled "Design and Evaluation of
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