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1.
基于泰勒级数展开的蜂窝TDOA定位算法   总被引:17,自引:0,他引:17  
熊瑾煜  王巍  朱中梁 《通信学报》2004,25(4):144-150
基于用户位置的应用已经成为移动数据业务的重要组成部分,使得蜂窝系统用户定位技术成为蜂窝移动通信领域的研究热点。泰勒级数展开算法因为具有精度高和顽健性强等特点而在求解非线性定位方程组中得到了广泛的应用,但它对初始值有很强的依赖性。本文使用最小二乘方法估计用户位置的初始值并使用泰勒级数展开算法确定用户坐标。通过对算法的仿真分析,结果表明本算法具有近似于基于真实值的泰勒级数展开算法的性能。  相似文献
2.
具有无穷时滞的细胞神经网络的稳定性分析   总被引:11,自引:2,他引:9  
本文研究了具有无穷时滞的细胞神经网络的全局吸引性问题,利用常数变易法和不等式分析技巧,给出了无穷时滞的细胞神经网络无平衡点时,网络系统有吸引聚集的充分条件,同时也给出了无穷时滞的细胞神经网络有平衡点时,网络系统的平衡点全局渐近稳定的充分条件,其结果推广了文[7,8]的相应结果。  相似文献
3.
室内可见光蜂窝网络信道特性研究   总被引:8,自引:7,他引:1  
基于可见光通信(VLC)技 术的LED蜂窝网络,设想作为第5代移动通信技术在室内应用的主要备选方式之一,得到越来 越多的关注。本 文采用广义光线追踪算法对符合蜂窝布局的室内可见光信道特性进行研究,分析了不同LED 发光角度条件 下信道冲击响应、路径损耗和信道时延等信道特性。随着LED半功率角从30°增大到60°, 系统路径损耗 与信道时延也整体增大,其中总体路径损耗变化范围为32~36.5dB ,信道时延的变化范围为0.4~1.5ns。  相似文献
4.
多业务无线蜂窝移动通信系统的一种呼叫允许控制策略   总被引:6,自引:0,他引:6  
朱立东  吴诗其 《通信学报》2001,22(11):11-21
第三代移动通信系统要求支持宽带多媒体业务,如话音、视频、数据等多种业务,不同业务有不同的QoS要求。本文提出的多业务无线蜂窝移动通信系统中一种基于QoS的呼收允许控制策略,对不同业务的切换呼叫给予不同的优先权。本文分析了两种呼叫允许控制(CAC)算法,一种是各种业务的切控呼叫无缓冲器,不进入排队系统;另一种是各种业务的切换呼叫设置有缓冲器,进入排除系统,并且话音、视频业务的切切呼叫比数据业务的切换呼叫有更高的优先权,系统的空闲信道应首先分配给话音、视频业务的切换呼叫,再分配给数据业务的切换呼叫。在分析两种CAC算法的呼叫阻塞概率、切换失败概率以及系统吞吐量的基础上,给出了计算机仿真结果。  相似文献
5.
蜂窝网络中环状搜索移动性管理策略   总被引:5,自引:2,他引:3  
朱艺华  高济  周根贵  彭静 《电子学报》2003,31(11):1655-1658
位置管理是移动通信领域的一个具有挑战性的问题,涉及到位置更新和位置查找操作,在现行蜂窝系统的位置管理策略(简称“基本策略”)中,一旦移动台越区,就需要进行位置更新,由于移动台的越区具有局部性,基本策略会造成系统资源的极大浪费。因此,降低位置管理的费用成为移动通信领域的一个研究热点,该文给出不需要进行位置更新的环状搜索位置管理策略(简称“环状策略”),并推导出搜索位置区平均层数的一个公式,然后利用这一公式对基本策略、指针推进策略与环状策略的费用进行了对比研究。得出:在一定条件下,环状策略的费用要比基本策略及基本指针推进策略小。  相似文献
6.
On Handoff Performance for an Integrated Voice/Data Cellular System   总被引:3,自引:0,他引:3  
One of the key challenges in the design of bandwidth allocation policies for a multi-services mobile cellular network is to guarantee the potentially different Quality of Service (QoS) requirement from diverse applications, while at the same to ensure that the scarce bandwidth be utilized efficiently. Complete Sharing (CS) and Dynamic Partition (DP) schemes have been shown as viable techniques for managing the bandwidth. However, there has been no study that compares their respective performance, which is the focus of this paper. Specifically, in this paper, through both analysis and simulation, we demonstrate that both schemes can achieve comparable performance by proper manipulation of control parameters. The tradeoff is that DP scheme can more easily achieve the target QoS requirement, at the expense of some over-provisioning, thus can potentially lead to less channel efficiency when comparing to a CS based scheme.  相似文献
7.
The fluctuation of available link bandwidth in mobilecellular networks motivates the study of adaptive multimediaservices, where the bandwidth of an ongoing multimedia call can bedynamically adjusted. We analyze the diverse objectives of theadaptive multimedia framework and propose two bandwidth adaptationalgorithms (BAAs) that can satisfy these objectives. The firstalgorithm, BAA-RA, takes into consideration revenue and``anti-adaptation' where anti-adaptation means that a user feelsuncomfortable whenever the bandwidth of the user's call ischanged. This algorithm achieves near-optimal total revenue withmuch less complexity compared to an optimal BAA. The secondalgorithm, BAA-RF, considers revenue and fairness, and aims at themaximum revenue generation while satisfying the fairnessconstraint defined herein. Comprehensive simulation experimentsshow that the difference of the total revenue of BAA-RA and thatof an optimal BAA is negligible. Also, numerical results revealthat there is a conflicting relationship between anti-adaptationand fairness.  相似文献
8.
软分数频率复用   总被引:2,自引:0,他引:2  
针对4G移动通信系统提出的提高频谱利用率、同频组网的需求,文章从频率复用问题入手,提出了一种软分数频率复用方案。软分数频率复用方案包括3种表现形式,在实际应用中,可以根据物理层链路增益选择适当的表现形式。文章以第2种表现形式为例介绍了采用该方案的频率复用方法。研究表明,使用软分数频率复用方案,系统的频率复用系数可以达到1/3~1。软分数频率复用方案解决了同频组网问题,并已经在上海4G实验网中得到了良好的应用。  相似文献
9.
In this paper, we study the hand-off performance of a wireless system with heterogeneous technologies called iCAR (Integrated Cellular and Ad hoc Relaying). In iCAR, hand-offs can occur not only from a Base Transceiver Station (BTS) to another BTS, but also from a BTS to a so-called Ad hoc Relaying Station (ARS) in the form of relaying, as well as from an ARS back to a BTS. The latter two types of hand-offs effectively increase the hand-off buffer time and thus reduce the call dropping probability. We develop an analytical model for the hand-off performance in iCAR. In addition, we verify the analytical model via simulations and quantify the hand-off performance benefits of the iCAR system over conventional cellular systems. It is anticipated that the analytical and simulation models reported in this paper will serve as a guideline to other researches on the inter-system hand-off involving heterogenous wireless technologies. This research is in part supported by NSF under the contract ANIR-ITR 0082916. Hongyi Wu is currently a tenure-track Assistant Professor at The Center for Advanced Computer Studies (CACS), University of Louisiana (UL) at Lafayette. He received his Ph.D degree in Computer Science from State University of New York (SUNY) at Buffalo in 2002. He received his M.S. degree from SUNY at Buffalo in 2000 and B.S. degree from Zhejiang University in 1996, respectively. He worked in Nokia Research Center in the summers of 2001 and 2000. His research interests include wireless mobile ad hoc networks, sensor networks, the next generation cellular systems, and the integrated heterogeneous wireless systems. He has served as the symposium chair, the session chair, and the technical committee member of several IEEE conferences, and the guest editor of ACM MONET special issue on Integration of Heterogeneous Wireless Technologies. He has published about two dozens of technical papers in leading journals and conference proceedings, as well as a book chapter. Swades De received his B.Tech degree in Radiophysics and Electronics from University of Calcutta, India, in 1993, M.Tech degree in Optoelectronics and Optical Communication from Indian Institute of Technology, Delhi, in 1998, and Ph.D degree in Electrical Engineering from State University of New York at Buffalo in 2004. During 1993-1997 he was a hardware development engineer and during the first half of 1999 he was a software engineer with different telecommunication companies in India. During first half of 2004, he was with the Istituto di Scienza e Technologie dell' Informazione, National Research Council (ISTI-CNR), Pisa, Italy, theough a European research fellowship. He is currently an Assistant Professor in the Department of Electrical and Computer Engineering, New Jersey Institute of Technology, Newark, NJ, USA. His His research interests include performance study, resource efficiency in multihop wireless and wireline networks, integrated wireless technologies, and communication and systems issues in optical networks. Dr. Chunming Qiao directs the Lab for Advanced Network Design, Analysis, and Research,(LANDER, which conducts cutting-edge research work on optical networks, wireless networks, survivable networks, and TCP/IP technologies. He has published more than one hundred twenty papers in leading technical journals and conference proceedings. His pioneering research on Optical Internet, in particular, the optical burst switching (OBS) paradigm is internationally acclaimed. In addition, his work on integrated cellular and ad hoc relaying systems (iCAR) is recognized as the harbinger for today's push towards the convergence between heterogeneous wireless technologies, and has been featured in Businessweek and Wireless Europe. Dr. Qiao have given several keynotes, tutorials and invited talks on the above research topics. He is on the editorial board of several journals and magazines including IEEE/ACM Transactions on Networking (ToN), and IEEE Communications Magazine, and have guest-edited several IEEE JSAC and ACM/Baltzer issues. He has chaired and co-chaired a dozen of international conferences and workshops including the High-Speed Networking Workshop (formerly GBN) at Infocom'01 and Infocom'02, Opticomm'02, and the symposium on Optical Networks at ICC'03. Evsen Yanmaz was born in Ankara, Turkey, in 1979. She received the B.S. degree in electrical and electronics engineering from Bogazi?i University, Istanbul, Turkey, in 2000, and the M.S. degree in electrical engineering from the State University of New York (SUNY) at Buffalo, Amherst, NY, in 2002. Currently, she is working toward the Ph.D. degree in electrical and computer engineering at Carnegie Mellon University, Pittsburgh, PA. From 2000 to 2002, she was a Research and Teaching Assistant at SUNY at Buffalo. Since 2002, she has been a Research Assistant at Carnegie Mellon University, where she has been working on congestion in cellular communication systems and dynamic load balancing schemes. Her current research interests are in resource allocation and congestion relief in heterogeneous wireless networks. Ozan K. Tonguz was born in Cyprus, in May 1960. He received the B.Sc. degree from the University of Essex, England, in 1980, and the M.Sc. and the Ph.D. degrees from Rutgers University, New Brunswick, NJ, in 1986 and 1990, respectively, all in electrical engineering. He is currently a tenured Full Professor in the Department of Electrical and Computer Engineering at Carnegie Mellon University (CMU). Before joining CMU in August 2000, he was with the ECE Dept. of the State University of New York at Buffalo (SUNY/Buffalo). He joined SUNY/Buffalo in 1990 as an Assistant Professor, where he was granted early tenure and promoted to Associate Professor in 1995, and to Full Professor in 1998. Prior to joining academia, he was with Bell Communications Research (Bellcore) between 1988–1990 doing research in optical networks and communication systems. His current research interests are in optical networks, wireless networks and communication systems, high-speed networking, and satellite communications. He has published in the areas of optical networks, wireless communications and networks, and high-speed networking. Author or coauthor of more than 150 technical papers in IEEE journals and conference proceedings, and a book chapter (Wiley, 1999), his contributions in optical networks and wireless networks are internationally acclaimed. His industrial experience includes periods with Bell Communications Research, CTI Inc., Harris RF Communications, Aria Wireless Systems, Clearwire Technologies, Nokia Networks, and Asea Brown Boveri (ABB). He currently serves as a consultant for several companies, law firms, and government agencies in USA and Europe in the broad area of telecommunications and networking. He is also a Co-Director (Thrust Leader) of the Center for Wireless and Broadband Networking Research at Carnegie Mellon University. In addition to serving on the Technical Program Committees of several IEEE conferences and symposia in the area of wireless communications and optical networks, Dr. Tonguz currently serves or has served as an Associate Editor for the IEEE TRANSACTIONS ON COMMUNICATIONS, IEEE COMMUNICATIONS MAGAZINE, and IEEE JOURNAL OF LIGHTWAVE TECHNOLOGY. He was a Guest Editor of the special issue of the IEEE JOURNAL OF LIGHTWAVE TECHNOLOGY AND IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS on Multiwavelength Optical Networks and Technology, published in 1996.  相似文献
10.
Modeling iCAR via Multi-Dimensional Markov Chains   总被引:2,自引:0,他引:2  
iCAR is a new wireless system architecture based on the integration of cellular and modern ad hoc relaying technologies. It addresses the congestion problem due to limited channel access in a cellular system and provides interoperability for heterogeneous networks. The iCAR system can efficiently balance traffic loads and share channel resource between cells by using ad hoc relaying stations (ARS) to relay traffic from one cell to another dynamically. Analyzing the performance of iCAR is nontrivial as the classic Erlang-B formula no longer applies when relaying is used. In this paper, we build multi-dimensional Markov chains to analyze the performance of the iCAR system in terms of the call blocking probability. In particular, we develop an approximate model as well as an accurate model. While it can be time-consuming and tedious to obtain the solutions of the accurate model, the approximate model yields analytical results that are close to the simulation results we obtained previously. Our results show that with a limited number of ARSs, the call blocking probability in a congested cell as well as the overall system can be reduced.  相似文献
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