一种无线局域网的实时接入方案

主要提出了一种基于CSMA/CA分布控制协议的实时接入方式。这种接入方式通过发送“竞争脉冲”和探询脉冲来主动占有信道,从而彻底避免实时站同其他站的冲突,减少延迟。并且从理论上对实时接入的稳定性条件及数据站的接入性能进行了分析。     

无线局域网MAC接入性能研究

主要研究无线局域网MAC接入性能,从IEEE 802.11协议、无线局域网接入性能两个方面对这个问题进行了研究,无线局域网灵活,安全性高,扩展方便的优势是有线网络不能比的,但是无线局域网MAC接入性能在复杂的网络运行环境下存在较大的波动,有必要对其进行深入研究。     

红外无线小型局域网的设计

本文论证了红外无线小型局域网的系统设计方案,提出了一种新的数据寻址和红外无线链路接入管理的方法。系统采用面向连接传输方式,整个通信规程易于实现,并具有一定的灵活性。     

无线局域网MAC标准

80 2 .1 1为无线局域网标准 ,其物理层的无线媒体决定了它与现有的有线局域网 (LAN)的媒体访问控制 (MAC)层不同 ,具有独特的媒体访问控制机制 ,各站以载波侦听多路访问 /碰撞避免 (CSMA /CA)的方式共享无线媒体。本文是在具体设计研制过程中 ,对MAC子层作了一些探讨 ,重点介绍MAC的分布协调功能(DCF)和点协调功能 (PCF)、MAC层服务及MAC帧格式等 ,并将其运用到了实际工作中。     

无线局域网MAC标准

８０２１１为无线局域网标准，其物理层的无线媒体决定了它与现有的有线局域网（ＬＡＮ）的媒体访问控制（ＭＡＣ）层不同，具有独特的媒体访问控制机制，各站以载波侦听多路访问／碰撞避免（ＣＳＭＡ／ＣＡ）的方式共享无线媒体。本文结合具体设计研制过程，介绍ＭＡＣ的分布式协调功能（ＤＣＦ）和点协调功能（ＰＣＦ）、及ＭＡＣ帧格式等。     

无线局域网MAC接入性能分析

文章主要介绍了无线局域网的发展和IEEE 802.11协议中MAC层的一些内容,分析了无线局域网的流量和平均帧时延性能,提出了RTS-Threshold参数以及信道误码对网络性能的影响,并通过仿真验证了最佳的参数配置的存在性,证明其同网络中站点数目是相关的。     

无线局域网技术应用与发展

文章对无线局域网的组网应用，以及无线局域网中主要使用的无线通信技术、频带、标准、媒质接入控制和发展趋势等做了比较详细的探讨。     

基于FPGA无线传感器网络MAC控制器的设计

给出了一种由FPGA实现的无线传感器网络MAC控制器的设计方法,采用自顶向下的方法设计各个模块,并在QuartusⅡ 8.0完成了仿真,该控制器主要支持IEEE802.15.4协议.测试结果表明,该MAC控制器支持20～250 kb·s<'-1>数据传输速率,适应IEEE802.15.4协议要求.     

IEEE802.11与高级红外无线AIr MAC协议的性能比较

红外线作为室内通信无线传输媒质,具有低成本、低功耗等特点.本文描述 了IEEE 802.11红外局域网媒质访问控制协议（MAC）和红外数据协会（IrDA）提出的高级红外媒质访问控制层协议（AIr MAC）;研究了两种协议性能估计模型并利用OPNET仿真工具对IEEE 802.11 MAC与高级红外AIr MAC接入性能进行了仿真验证.通过对两种MAC协议接入方式、吞吐量性能估计模型以及吞吐量性能仿真结果进行比较分析,总结了IEEE 802.11红外局域网媒质接入协议和高级红外媒质接入协议之间的不同之处.     

无线局域网MAC层QoS研究

在分析无线网协议提供QoS保证方面存在的问题的基础上，讨论了IEEE802．11e的两个新的策略：增强的分布式协调功能和混合协调功能。通过对受控竞争机制的分析．指出了IEEE802．11e仍存在的不足及未来的发展方向。     

Performance Analysis of the Advanced Infrared (AIr) CSMA/CA MAC Protocol for Wireless LANs

Advanced Infrared (AIr) is a proposed standard of the Infrared Data Association (IrDA) for indoor infrared LANs. AIr Medium Access Control (MAC) employs Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) techniques with Request To Send/Clear To Send (RTS/CTS) frame exchange to address the hidden station problem. A long Collision Avoidance Slot (CAS) duration, that includes the beginning of the CTS frame, is defined to cope with collisions caused from hidden stations. AIr MAC employs linear adjustment of the Contention Window (CW) size to minimize delays emerging from the long CAS duration. This paper provides a simple and accurate analytical model for the linear CW adjustment that calculates AIr throughput assuming a finite number of stations and error free channel transmissions. Validity of the model is verified by comparing analysis with simulation results. By examining the first derivative of the throughput equation, we derive the optimum CW size that maximizes throughput as a function of the network size. In the case of the AIr protocol, where a collision lasts exactly one CAS, different conclusions result for maximum throughput as compared with the corresponding conclusions for the similar IEEE 802.11 protocol. Using the proposed model, we present an extensive AIr throughput performance evaluation. The effectiveness of physical and link layer parameters on throughput performance is explored. The proposed long CAS duration combined with CW linear adjustment are proven quite effective. Linear CW adjustment combined with the long CAS duration offer an efficient collision avoidance scheme that does not suffer from collisions caused from hidden stations.     

一种基于ARM和FPGA的可重构MAC协议设计

为了在实际信道条件下研究AdHoc网络MAC协议,克服商业网卡芯片和理论仿真等带来的局限性,搭建了基于ARM和FPGA相结合的硬件平台,设计与实现了基于CSMA／cA的可重构MAC协议,并进行了仿真测试,验证了该协议设计的正确性。对AdHoc网络MAC协议的实用化提供有益的参考。     

无线局域网在医院中的应用及安全防护

随着无线技术的发展和移动智能终端的普及,医疗行业对无线网络的需求也越来越多,建设医院无线局域网,能提高工作效率和服务质量。文章提出了以无线控制器和AP为架构形式的无线局域网的解决方案,能克服传统无线网络漫游、无法统一管理等的问题,同时给出了安全防护的措施,从而为医院建立一个稳定安全的无线网络环境。     

Performance of Carrier Sense Multiple Access with Collision Avoidance Protocols in Wireless LANs

The performance of Carrier Sense Multiple Access/Collision Avoidance (CSMA/CA) protocols, which is adopted as a draft standard in IEEE 802.11, is analyzed in the view of throughput and packet delay. We consider three kinds of CSMA/CA protocols, which include Basic, Stop-and-Wait and 4-Way Handshake CSMA/CA, and introduce a theoretical analysis for them. First, we consider that a network consists of a finite population and then expand to an infinite population model. We model the CSMA/CA protocol as a hybrid protocol of a 1-persistent CSMA and a p-persistent CSMA protocol. We calculate the throughput and packet delay for three kinds of CSMA/CA protocols and verify analytical results by computer simulation. We have found that 4-Way Handshake CSMA/CA shows better performance than those of other two type CSMA/CA in high traffic load and analytical results are very close to simulation ones.     

无线局域网技术的分析与研究

介绍了无线局域网的基本组成、拓扑结构、优缺点及其关键技术，详述了几种无线局域网标准．并列出无线局域网的安全问题和详细解决方案。     

High Performance Wireless Switch Protocol for IEEE 802.11 Wireless Networks

All mobile stations (STAs) in IEEE 802.11 infrastructure wireless local area networks (IWLAN) are coordinated by an access point (AP). Within the 2.4 GHz unlicensed industry, science, and medicine (ISM) band defined in the IEEE 802.11 2.4 GHz physical layer (PHY) specifications, three channels are available for concurrently transferring data packets at the coverage area of an AP. In most of small/medium enterprises or home environments, an AP with one selected channel is sufficient for covering whole service area, but this implies that the radio resources for the remaining two channels are wasted. In order to overcome the drawback, we propose a new and simple media access control (MAC) protocol, named wireless switch protocol (WSP), for increasing the throughput of IEEE 802.11 IWLAN network to support high quality multimedia traffic. This is achieved by allowing any pair of STAs in IWLAN to exchange data packets in one of other idle channels after their handshake with each other in the common channel controlled by AP. Simulation results show that the total network throughput of WSP depends on the time taken by channel switching, and on the ‘Intranet’ and ‘Internet’ traffic distribution, where the Intranet and Internet mean data transmission between STAs in IWLAN and between the STA and wired host, respectively. When all data packets are Intranet traffic and the traffic load is heavy, the ratio of Goodput for the proposed WSP to that of IEEE 802.11 standard approximates 400%. In the worse case of all Internet traffic, the proposed WSP still obtains the similar throughput as that of IEEE 802.11 standard.Jenhui Chen was born on October 12, 1971 in Taipei, Taiwan, Republic of China. He received the Bachelor’s and Ph.D. degree in Computer Science and Information Engineering (CSIE) from Tamkang University in 1998 and 2003, respectively. In the Spring of 2003, he joined the faculty of Computer Science and Information Engineering Department at Chang Gung University and served as the Assistant Professor. He occupies the supervisor of Network Department in the Information Center, Chang Gung University. Dr. Chen once served the reviewer of IEEE Transactions on Wireless Communications, ACM/Kluwer Mobile Networks and Applications (MONET), and Journal of Information Science and Engineering. His main research interests include design, analysis, and implementation of communication and network protocols, wireless networks, milibots, and artificial intelligence. He is a member of ACM and IEEE.Ai-Chun Pang was born in Hsinchu, Taiwan, R.O.C., in 1973. She received the B.S., M.S. and Ph.D. degrees in Computer Science and Information Engineering from National Chiao Tung University (NCTU) in 1996, 1998 and 2002, respectively. She joined the Department of Computer Science and Information Engineering, National Taiwan University (NTU), Taipei, Taiwan, as an Assistant Professor in 2002. Her research interests include design and analysis of personal communications services network, mobile computing, voice over IP, and performance modeling.Shiann-Tsong Sheu received his B.S. degree in Applied Mathematics from National Chung Hsing University in 1990, and obtained his Ph.D. degree in Computer Science from National Tsing Hua University in May of 1995. From 1995 to 2002, he was an Associate Professor at the Department of Electrical Engineering, Tamkang University. Since Feb. 2002, he has become a Professor at the Department of Electrical Engineering, Tamkang University. Dr. Sheu received the outstanding young researcher award by the IEEE Communication Society Asia Pacific Board in 2002. His research interests include next-generation wireless communication, WDM networks and intelligent control algorithms.Hsueh-Wen Tseng received his B.S. degree in electrical engineering from Tamkang University, Taipei country, Taiwan, in 2001 and M.S. degree in electrical engineering from National Taiwan University of Science and Technology, Taipei, Taiwan, in 2003. He is currently pursuing the Ph. D. degree at the Department of Computer Science and Information Engineering, National Taiwan University, Taipei, Taiwan. His research interests include design, analysis and implementation of network protocols and wireless communications.     

基于IEEE 802.15.4的CSMA/CA性能分析与研究

针对目前无线传感器网络所采用的IEEE802.15.4通讯协议进行研究及分析,包括了碰撞发生后的重传机制,也就是IEEE 802.15.4所使用的CSMA/CA算法,对于整体网络通信所造成的影响.经分析评估以及程序仿真后,将针对网络状况来找出CSMA/CA算法的三个重要参数对系统性能的影响.     

认知无线电网络的MAC协议机制

针对认知无线电网络可用信道资源随时间和空间环境变化的特点,分析了认知无线电网络MAC协议面临的问题,提出了一种基于全局控制信道的MAC协议方案,在此基础上阐述了两种接入方式及相应适用场合,实现了认知无线电节点对可用信道资源变化的感知,可为认知无线电MAC协议研究及应用提供参考.