3G wireless communications for mobile robotic tele-ultrasonography systems

Mobile healthcare (m-health) is a new paradigm that brings together the evolution of emerging wireless communications and network technologies with the concept of 'connected healthcare' anytime and anywhere. In this article, we present the performance analysis of an end-to-end mobile tele-echography using an ultra-light robot (OTELO), over the third-generation (3G) mobile communications network. The experimental setup of the OTELO system over a 3G connectivity link used to measure the system performance is described. The performance of the relevant medical data and the relevant quality of service (QoS) issues defined in terms of the average throughput, delta-time packet delay, and jitter delay are investigated. The real-time 3G performance results show the successful operation of this bandwidth demanding robotic m-health system.     

Markov chain model of fault-tolerant wireless networked control systems

Wireless Networks - Wireless networked control systems (WNCS) are composed of spatially distributed sensors, actuators, and controllers communicating through wireless networks instead of...     

无形变视差调节快速算法

针对目前的3D播放器使用简便快捷的拉伸和平移算法实现深度感的调节产生明显的图像形变问题,本文提出了一种精确的视差调节模型,但模型调节视差需要获取原始深度值,计算复杂度高,导致难以流畅播放高分辨率3D视频图像。为此,进一步引入最小形变可察觉范围,通过假设原始深度的统计模型,把形变大小控制在最小形变可察觉范围内,在复杂度与形变程度上作出适当的平衡。VLC播放器实验表明,相比传统方法,本文算法形变程度降低超过50%,立体视觉主观效果更好;对于高清视频,算法效率提高48%。     

Novel semi-blind ICI equalization algorithm for wireless OFDM systems

Intercarrier interference is deemed as one of the crucial problems in the wireless orthogonal frequency division multiplexing (OFDM) systems. The conventional ICI mitigation schemes involve the frequency-domain channel estimation or the additional coding, both of which require the spectral overhead and hence lead to the significant throughput reduction. Besides, the OFDM receivers using the ICI estimation rely on a large-dimensional matrix inverter with high computational complexity especially for many subcarriers such as digital video broadcasting (DVB) systems and wireless metropolitan-area networks (WMAN). To the best of our knowledge, no semi-blind ICI equalization has been addressed in the existing literature. Thus, in this paper, we propose a novel semi-blind ICI equalization scheme using the joint multiple matrix diagonalization (JMMD) algorithm to greatly reduce the intercarrier interference in OFDM. However, the well-known phase and permutation indeterminacies emerge in all blind equalization schemes. Hence we also design a few OFDM pilot blocks and propose an iterative identification method to determine the corresponding phase and permutation variants in our semi-blind scheme. Our semi-blind ICI equalization algorithm integrating the JMMD with the additional pilot-based iterative identification is very promising for the future high-throughput OFDM systems. Through Monte Carlo simulations, the QPSK-OFDM system with our proposed semi-blind ICI equalizer can achieve significantly better performance with symbol error rate reduction in several orders-of-magnitude. For the 16QAM-OFDM system, our scheme can also improve the performance over the plain OFDM system to some extent.     

多跳无线传感器网络的高效中继节点快速选择算法

针对多跳无线传感器网络数据收集协议中继转发节点选择算法效率不高的问题,提出了一种能量有效的中继节点快速选择 (EERNFS)算法.EERNFS算法利用分时共享信道的方法维护网络同步和更新节点的邻居信息,使节点在每个网络侦听/睡眠周期依赖一定的概率同步激活唤醒,确保了网络节点瞬时连通度的稳定和一致;基于网络节点的地理优先级、节点价值和链路质量的分布式估计,EERNFS算法采用竞争的方法选择中继转发节点, 使用乘性增加时间窗口的方法,分解候选中继节点间的竞争.理论分析和模拟实验结果表明,EERNFS算法在能效、数据传递的平均时延、分组到达率等网络性能指标上显著优于FFS和GeRaF算法,极大地延长了网络的寿命.     

无线通信系统通道校准算法研究

多通道无线通信系统中各通道的校准是关键技术,通过设计特定的训练序列,并采用高效的快速算法,在线实时校正阵列天线系统多个通道的幅度和相位.分析了发射通道和接收通道的性能,理论分析和计算机仿真结果表明,该算法能校正通道之间的幅度和相位误差,而且实现简单,具有较好的校准性能.     

A rendezvous reservation protocol for energy constrained wireless infrastructure networks

This paper considers a low power wireless infrastructure network that uses multi-hop communications to provide end user connectivity. A generalized Rendezvous Reservation Protocol (RRP) is proposed which permits multi-hop infrastructure nodes to adapt their power consumption in a dynamic fashion. When nodes have a long-term association, power consumption can be reduced by having them periodically rendezvous for the purpose of exchanging data packets. In order to support certain applications, the system invokes a connection set up process to establish the end-to-end path and selects node rendezvous rates along the intermediate nodes to meet the application’s quality of service (QoS) needs. Thus, the design challenge is to dynamically determine rendezvous intervals based on incoming applications’ QoS needs, while conserving battery power. In this paper, we present the basic RRP mechanism and an enhanced mechanism called Rendezvous Reservation Protocol with Battery Management (RRP-BM) that incorporates node battery level information. The performance of the system is studied using discrete-event simulation based experiments for different network topologies. The chief metrics considered are average power consumption and system lifetime (that is to be maximized). The QoS metrics specified are packet latency and end-to-end setup latency. It is shown that the use of the RRP-BM can increase the lifetime up to 48% as compared to basic RRP by efficiently reducing the energy consumption. This work was supported by a grant from the Natural Sciences and Engineering Research Council of Canada and Communications and Information Technology Ontario (CITO). Part of the research was supported by Air Force Office of Scientific Research grants F-49620-97-1-0471 and F-49620-99-1-0125; Laboratory for Telecommunications Sciences, Adelphi, Maryland; and Intel Corporation. The authors may be reached via e-mail at todd@mcmaster. ca, krishna@umbc. edu. The basic RRP mechanism was presented at the IASTED International Conference on Wireless and Optical Communications, Banff, Canada, July 2002. Subalakshmi Venugopal received her Bachelors in Computer Science from R.V. College of Engineering, Bangalore, India and her M.S. degree in Computer Science from Washington State University. She interned as a student researcher at the Indian Institute of Science, Bangalore, India. Ms. Venugopal is currently employed with Microsoft Corporation in Redmond, WA and is part of the “Kids and Education Group”. Her research interests include low power wireless ad hoc networks. Zhengwei (Wesley) Chen received the M.E. in Electrical & Computer Engineering Dept from McMaster University in Canada in 2002. He joined Motorola Inc. as a CDMA2000 system engineer in 2000. In 2002, he joined UTStarcom as a manager of the Global Service Solution Department. He is currently in charge of R&D for Advanced Services related to the TVoIP and Softswitch products. Terry Todd received the B.A.Sc, M.A.Sc and Ph.D degrees in Electrical Engineering from the University of Waterloo in Waterloo, Ontario, Canada. While at Waterloo he also spent 3 years as a Research Associate with the Computer Communications Networks Group (CCNG). During that time he worked on the Waterloo Experimental Local Area Network, which was an early local area network testbed. In 1991 Dr. Todd was on research leave in the Distributed Systems Research Department at AT&T Bell Laboratories in Murray Hill, NJ. He also spent 1998 as a visiting researcher at The Olivetti and Oracle Research Laboratory (ORL) in Cambridge, England. While at ORL he worked on the piconet project, which was an embedded low power wireless network testbed. Dr. Todd is currently a Professor of Electrical and Computer Engineering at McMaster University in Hamilton, Ontario, Canada. At McMaster he has been the Principal Investigator on a number of major research projects in the optical and wireless networking areas. He currently directs a large group working on wireless mesh networks and wireless VoIP. Professor Todd holds the NSERC/RIM/CITO Chair on Pico-Cellular Wireless Internet Access Networks. Dr. Todd’s research interests include metropolitan/local area networks, wireless communications and the performance analysis of computer communication networks and systems. Professor Todd is a Professional Engineer in the province of Ontario. Krishna M. Sivalingam is an Associate Professor in the Dept. of CSEE at University of Maryland, Baltimore County. Previously, he was with the School of EECS at Washington State University, Pullman from 1997 until 2002; and with the University of North Carolina Greensboro from 1994 until 1997. He has also conducted research at Lucent Technologies’ Bell Labs in Murray Hill, NJ, and at AT&T Labs in Whippany, NJ. He received his Ph.D. and M.S. degrees in Computer Science from State University of New York at Buffalo in 1994 and 1990 respectively; and his B.E. degree in Computer Science and Engineering in 1988 from Anna University, Chennai (Madras), India. While at SUNY Buffalo, he was a Presidential Fellow from 1988 to 1991. His research interests include wireless networks, optical wavelength division multiplexed networks, and performance evaluation. He holds three patents in wireless networks and has published several research articles including more than thirty journal publications. He has published an edited book on Wireless Sensor Networks in 2004 and edited books on optical WDM networks in 2000 and 2004. He served as a Guest Co-Editor for special issues of the ACM MONET journal on “Wireless Sensor Networks” in 2003 and 2004; and an issue of the IEEE Journal on Selected Areas in Communications on optical WDM networks (2000). He is co-recipient of the Best Paper Award at the IEEE International Conference on Networks 2000 held in Singapore. His work has been supported by several sources including AFOSR, NSF, Cisco, Intel and Laboratory for Telecommunication Sciences. He is a member of the Editorial Board for ACM Wireless Networks Journal, IEEE Transactions on Mobile Computing, Ad Hoc and Sensor Wireless Networks Journal, and KICS Journal of Computer Networks. He serves as Steering Committee Co-Chair for IEEE/CreateNet International Conference on Broadband Networks (BroadNets) that was created in 2004. He is currently serving as General Co-Vice-Chair for the Second Annual International Mobiquitous conference to be held in San Diego in 2005 and as General Co-Chair for the First IEEE/CreateNet International Conference on Security and Privacy for Emerging Areas in Communication Networks (SecureComm) to be held in Athens, Greece in Sep. 2005. He served as Technical Program Co-Chair for the First IEEE Conference on Sensor and Ad Hoc Communications and Networks (SECON) held at Santa Clara, CA in 2004; as General Co-Chair for SPIE Opticomm 2003 (Dallas, TX) and for ACM Intl. Workshop on Wireless Sensor Networks and Applications (WSNA) 2003 held in conjunction with ACM MobiCom 2003 at San Diego, CA; as Technical Program Co-Chair of SPIE/IEEE/ACM OptiComm conference at Boston, MA in July 2002; and as Workshop Co-Chair for WSNA 2002 held in conjunction with ACM MobiCom 2002 at Atlanta, GA in Sep 2002. He is a Senior Member of IEEE and a member of ACM.     

一种改进的快速嵌入式字符识别方法

针对手持式字符识别系统开发中系统对实时性要求较高、系统资源有限以及传统的支持向量机(SVM)分类方法难以同时满足识别率和识别速度的缺点,提出一种快速的SVM(FCSVM)分类算法。对支持向量集采用变换的方式,用少量的支持向量代替全部支持向量进行分类计算,在保证不损失分类精度的前提下使得分类速度较传统SVM算法有较大提高。实验结果表明,FCSVM算法较大幅度地减少了计算复杂度,提高了分类速度,尤其在嵌入式系统中效果更加明显。     

一种新的MIMO无线通信系统链路自适应算法

提出并分析了一种适用于MIMO系统的新的链路自适应算法。通过接收端估计信噪比,并利用各种编码调制方式的特性,该算法在接收端采用递归的方法确定了每一个发射端子信道所采用的编码调制方式,使反向链路仅传输少量的控制信息,实现了链路的自适应。仿真结果表明,文章所提出的算法大大提高了MIMO系统的吞吐量,且可靠性也显著增加。     

Detection of interruption attack in the wireless networked closed loop industrial control systems

Telecommunication Systems - Due to tremendous growth in the network, security is a major concern and it is gaining a high level of attention in the system. In the Industrial control systems such as...     

An asynchronous neighbor discovery algorithm for wireless sensor networks

We consider the problem of determining, in a distributed, asynchronous and scalable manner, what nodes are “neighbors” in a wireless network. Neighbor discovery is an important enabler of network connectivity and energy conservation. An asynchronous, probabilistic neighbor discovery algorithm is presented that permits each node in the network to develop a list of its neighbors, which may be incomplete. The algorithm is analyzed and parameter settings are derived which maximize the fraction of neighbors discovered in a fixed running time. A companion distributed algorithm is also described which allows all the nodes in the network to execute that neighbor discovery algorithm without the need to agree on a common start time.     

A fast time slot assignment algorithm for TDM hierarchicalswitching systems

A fast (polynomial time) network-flow-based algorithm is presented for time slot assignment in time-division-multiplexing (TDM) hierarchical switching systems. For a nonblocking time-multiplexed central switch the algorithm produces a conflict-free time slot assignment for a given frame (whenever this is possible) on O(M ⁵) time, where M is the system size     

无线多媒体传感器网络中一种改进路由算法

随着网络负载增加,经典的TPGF( Two-Phase geographic Greedy Forwarding)算法难以找到节点分离路径,会导致网络吞吐量、投递率以及端到端时延性能下降。此外,当网络拓扑变动不大时, TPGF中每条路径所包含节点要消耗比其他节点更多的能量,会导致其过快死亡,从而影响网络性能。为此,将联合网络编码技术引入 TPGF,提出一种编码与能量感知的 TPGF 路由算法( NE-TPGF)。该算法综合考虑节点的地理位置、编码机会、剩余能量等因素,同时利用联合网络编码技术进一步扩展编码结构,充分利用网络编码优势来建立相对最优的传输路径。仿真结果表明, NE-TPGF能够增加编码机会,提高网络吞吐量和投递率,降低端到端时延,并且还有利于减少和平衡节点的能量消耗。     

一种适用于多径衰落无线信道的快速盲均衡算法研究

在无线数字通信中,信道衰落和多途传播效应引起的码间干扰,严重影响了通信的有效性和可靠性,盲均衡是对抗码间干扰的有效方法。文章研究了一种适用于无线信道的快速盲均衡算法,并进行了计算机仿真。仿真结果表明,在算法剩余均方误差非常接近的情况下,该算法快于传统的常数模算法。     

A new fast polling algorithm in wireless mesh network for narrowband Internet of Things

Telecommunication Systems - We present a new fast polling algorithm (FPA) in a wireless mesh network (WMN) for Narrowband Internet of Things systems using multi-hop WMNs. We focus on wireless...     

一种改进的一维Otsu快速算法

阈值分割是众多图像分割方法中使用最普遍的一种方法,阈值的求解也是图像处理的重心。传统Otsu算法属于穷举式的阈值求解方法,需遍历每个灰度值并计算以其为阈值的类间方差,在此进行了大量不必要的计算,可能无法应用于某些实时性要求较高的环境中。对此提出一种快速的Otsu改进算法,在引入图像复杂度及其相关性质缩小了灰度的搜索范围,同时在搜索范围内使用了一种快速计算方法,较传统Otsu算法进行了二次加速。实验结果证明,该算法较传统Otsu算法提高了计算速度,且两种算法的图像分割结果相同。     

一种改进的快速最小K邻居定位算法

根据现有的基于信号强度的室内无线定位算法,结合二分查找的思想,提出了一种具有较低复杂度的室内无线定位算法,即快速最小K邻居定位算法。该算法通过将定位区域划分为多个子区域,利用优化的计算迅速缩小定位区域,再反复利用同样方法进一步缩小定位区域,得到极小的定位区域。最后在最小区域内通过最近K邻居定位算法估计待测点的位置。通过仿真证明,相比于现有的最小K邻居定位算法,该算法在损失极小的定位精度的同时极大的降低了定位复杂度。     

An improvement of DV-Hop localization algorithm for wireless sensor networks

An improved DV-HOP localization algorithm is proposed based on the traditional DV-HOP localization algorithm in the paper. There will be a big error that using the nearest anchor node’s average hop distance instead of the average hop distance of all the anchor nodes that involved in the localizing in the traditional DV-HOP localization algorithm. Therefore, the improved algorithm introduces threshold M, it uses the weighted average hop distances of anchor nodes within M hops to calculate the average hop distance of unknown nodes. In addition, the positioning results are corrected in the improved algorithm. The simulation results show that the new localization algorithm effectively improves the positioning accuracy compared with the traditional DV-HOP localization algorithm, it is an effective localization algorithm in the wireless sensor networks.     

VEPSD: a novel velocity estimation algorithm for next-generation wireless systems

A novel algorithm called velocity estimation using the power spectral density (VEPSD), which uses the Doppler spread in the received signal envelope to estimate the velocity of a mobile user (MU), is introduced in this paper. The Doppler spread is estimated using the slope of the power spectral density (PSD) of the received signal envelope. The performance of the VEPSD algorithm is evaluated in both Rayleigh and Rician fading environments. The sensitivity of the estimation error to additive white Gaussian noise (AWGN), Rice factor (K), and the angle of arrival of the line-of-sight (LOS) component is analyzed and compared with the level crossing rate (LCR) and covariance-based velocity estimators. Simulation results show that VEPSD estimates the velocity of MUs accurately. It is also shown that VEPSD can be used for velocity estimation under nonisotropic scattering and is well suited for next-generation wireless systems (NGWSs).     

A low complexity VBLAST OFDM detection algorithm for wireless LAN systems

A low complexity detection algorithm for VBLAST OFDM system is presented. Using the fact that the correlation among neighboring subcarriers is high for wireless LAN channels, this algorithm significantly reduces the complexity of VBLAST OFDM detection. The performance degradation of the proposed algorithm is small compared to conventional detection.