OMA DM协议在WiMAX中的应用

OMADM协议在WiMAX论坛开放零售认证计划中扮演者重要的角色。OMADM协议分成初始化引导和数据交互两个阶段,WiMAX论坛分别定义了不同的测试环境。尽快掌握OMADM协议相关的测试内容和测试方法,对WiMAX设备厂商顺利开展新的认证有着很大的帮助。文章首先介绍了开放零售认证计划的背景和OMADM协议,然后结合WiMAX认证的测试项目,介绍OMADM协议在WiMAX中的应用。     

如何降低企业库存成本

经济发展隐含诸多变数,如今世界经济正面临着千变万化的不透明时代.企业经营必须拥有适时而恰当的库存管理,因为库存资产在各企业的总资产额中所占的比率极为可观,管理的适当与否对企业经营的利润改善有很大的影响,同时也已经成为左右企业盛衰乃至存废的关键之一.     

城域光网络及其组网技术

本文从光网络的发展引出城域光网络(MON)的概念,在分析城域光网络的特点以后,总结出构建MON的准则及其组网考虑,最后分析了几种MON的组网技术,指出以SDH为基础的多业务传送平台(MSTP)是当前建设MON的首选技术途径.     

Low complexity concurrent constant modulus algorithm and soft decision directed scheme for blind equalisation

The recently introduced concurrent constant modulus algorithm (CMA) and decision-directed (DD) scheme provides a state-of-the-art low-complexity blind equalisation technique for high-order quadrature amplitude modulation (QAM) channels. At a small cost of slightly more than doubling the complexity of the standard CMA blind equaliser, this concurrent CMA and DD blind equaliser achieves a dramatic improvement in equalisation performance over the CMA. In the paper, a new blind equalisation scheme is proposed based on concurrent CMA and a novel soft decision-directed (SDD) adaptation. The proposed concurrent CMA and SDD blind equaliser has simpler computational requirements than the concurrent CMA and DD algorithm. Extensive simulation shows that it has the same steady-state equalisation performance as the concurrent CMA and DD algorithm and a faster convergence speed over the latter scheme     

Novel design for small-size coplanar waveguide frequency tripler

This letter presents a novel design for a small-size coplanar waveguide frequency tripler. In this study, a new BPF has been replaced the conventional stub lines in the output termination of the multiplier. Not only enhance the performance of the tripler, but also reduce the whole circuit size. to 2.125/spl times/2.275 cm/sup 2/ in the frequency 0.8/2.4 GHz, The spurious suppressions are 37.48, 33.38, and 32.08 dBc for the 1st, 2nd, and 4th harmonics, respectively. It reveals the best output power of -1.92 dBm for a 0 dBm input signal and maximum conversion gain of -1.92 dB. It is very useful for applications in the wireless communication and radar systems.     

Algorithms of halftoning color images with edge enhancement

Printers usually generate a limited number of colors and lack the ability of producing continuous-tone color images. Traditional error-diffusion algorithms are used to solve this problem. Compared with other approaches, the approaches of using error-diffusion in general can generate halftoned images of better quality. However, smeared edges and textures may occur in these halftoned images. To produce halftoned images of higher quality, these artifacts due to unstable images, dot-overlap, and error-diffusion must be eliminated or reduced. In this paper, we show that unstable images can be eliminated or reduced through using a proper color difference formula to select the reproduction colors even vector error-diffusion is performed in the RGB domain. We also present a method of using different filters to halftone different components of a color. This approach may have clearer and sharper edges for halftoned color images. Unexpected colors may be generated due to dot-overlap in the printing process. We have presented a method to eliminate this color distortion in the process of error-diffusion. Halftoning a color image by our proposed error-diffusion algorithm with edge enhancement has the following characteristics: the unstable images do not exist; the color-error caused by dot-overlap is corrected; and the smeared edges are sharpened.     

"领航论坛"主持人寄语

在这错综复杂与风云变幻的国内外电信新环境中,如何把握好发展方向及战略决策已成当务之急。开办“领航论坛”这一栏目的初衷, 即期望提供一种机会,使电信,特别是无线通信领域中引领潮流的重量级资深决策者发表战略决策真知灼见,为无线通信产业、市场及新技术、新业务的持续、快速、稳妥、健康发展领航导向。中兴通讯公司是我国众多电信制造商中自主开发、成功地连接市场、并有效走出国门面向世界的佼佼者,亦素以稳健、求实而闻名。中兴成功的根本在于它首先注重严密的战略规划,科学务实地处理好市场驱动导向与技术驱动支撑的辩证关系,能及…     

基于移动Agent的电子商务通信研究

移动Agent是将人工智能和网络技术结合,为解决复杂、动态、分布式智能应用提出的一种全新的计算方式,它的智能性、动态性和移动性特点为电子商务的智能资源发现和网上自动交易提供了技术支持。着重论述了移动Agent技术在电子商务中应用的基本原理,并设计了基于JAVA的移动Agent通信原语集。     

An unequal cluster-based routing protocol in wireless sensor networks

Clustering provides an effective method for prolonging the lifetime of a wireless sensor network. Current clustering algorithms usually utilize two techniques; selecting cluster heads with more residual energy, and rotating cluster heads periodically to distribute the energy consumption among nodes in each cluster and extend the network lifetime. However, they rarely consider the hot spot problem in multihop sensor networks. When cluster heads cooperate with each other to forward their data to the base station, the cluster heads closer to the base station are burdened with heavier relay traffic and tend to die much faster, leaving areas of the network uncovered and causing network partitions. To mitigate the hot spot problem, we propose an Unequal Cluster-based Routing (UCR) protocol. It groups the nodes into clusters of unequal sizes. Cluster heads closer to the base station have smaller cluster sizes than those farther from the base station, thus they can preserve some energy for the inter-cluster data forwarding. A greedy geographic and energy-aware routing protocol is designed for the inter-cluster communication, which considers the tradeoff between the energy cost of relay paths and the residual energy of relay nodes. Simulation results show that UCR mitigates the hot spot problem and achieves an obvious improvement on the network lifetime. Guihai Chen obtained his B.S. degree from Nanjing University, M. Engineering from Southeast University, and PhD from University of Hong Kong. He visited Kyushu Institute of Technology, Japan in 1998 as a research fellow, and University of Queensland, Australia in 2000 as a visiting professor. During September 2001 to August 2003, he was a visiting professor at Wayne State University. He is now a full professor and deputy chair of Department of Computer Science, Nanjing University. Prof. Chen has published more than 100 papers in peer-reviewed journals and refereed conference proceedings in the areas of wireless sensor networks, high-performance computer architecture, peer-to-peer computing and performance evaluation. He has also served on technical program committees of numerous international conferences. He is a member of the IEEE Computer Society. Chengfa Li was born 1981 and obtained his Bachelor’s Degree in mathematics in 2003 and his Masters Degree in computer science in 2006, both from Nanjing University, China. He is now a system programmer at Lucent Technologies Nanjing Telecommunication Corporation. His research interests include wireless ad hoc and sensor networks. Mao Ye was born in 1981 and obtained his Bachelor’s Degree in computer science from Nanjing University, China, in 2004. He served as a research assistant At City University of Hong Kong from September 2005 to August 2006. He is now a PhD candidate with research interests in wireless networks, mobile computing, and distributed systems. Jie Wu is a professor in the Department of Computer Science and Engineering at Florida Atlantic University. He has published more than 300 papers in various journal and conference proceedings. His research interests are in the areas of mobile computing, routing protocols, fault-tolerant computing, and interconnection networks. Dr. Wu serves as an associate editor for the IEEE Transactions on Parallel and Distributed Systems and several other international journals. He served as an IEEE Computer Society Distinguished Visitor and is currently the chair of the IEEE Technical Committee on Distributed Processing (TCDP). He is a member of the ACM, a senior member of the IEEE, and a member of the IEEE Computer Society.     

Contention-aware prediction for performance impact of task co-running in multicore computers

Wireless Networks - In this paper, we investigate the influential factors that impact on the performance when the tasks are co-running on a multicore computers. Further, we propose the machine...