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101.
随着移动技术以及数字化技术的飞速发展和广泛应用,各类便携式、多功能、可移动智能终端的普及人们对移动学习和移动办公提出了更高的要求,建设新一代支持移动学习的无线校园网应运而生.研究支持移动学习的无线校园网建设规划和设计,探讨无线校园网IPv6的支持,并提出移动学习应用需求. 相似文献
102.
采用高级安全策略的无线网络在漫游时要忍受较大的时延,在不牺牲安全性的前提下快速灵活地漫游于无线局域之间成了无线局域网搭建的重中之重。基于IEEE 802.11r协议的快速BSS切换协议,以及对密钥结构和认证过程的较大改动,采用三层漫游技术实现了能够无缝漫游的校园无线网络,经过近1年的运营证明,该文提出的方案切实有效。 相似文献
103.
Kenan Xu Quanhong Wang Hossam Hassanein 《International Journal of Communication Systems》2005,18(7):619-637
This paper proposes a multi‐dimensional Markov model to analyse the performance of the IEEE 802.11e EDCF MAC protocol. Based on this model, we present extensive performance evaluation in terms of throughput, throughput ratios, and access delay of flows of distinct priorities under RTS/CTS mode. We also provide quantitative analysis of the impact of prioritized parameters, i.e. Arbitration InterFrame Space (AIFS), Contention Window (CW) on Quality of Service (QoS) differentiation. The accuracy of the proposed model is verified by means of comparing the numerical results obtained from both analytical model and simulations. Our research can be used as a guideline for the prediction of how flows belonging to a certain Traffic Category (TC) perform with their TC‐specific parameters, as well as designing EDCF‐based WLANs and tuning the parameters to achieve the desirable differentiated QoS objectives. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
104.
详细分析了WLAN(无线局域网)的最新安全标准IEEE 802.11i,包括标准体系结构、接入认证和访问控制以及加密机制;同时,分析了该标准的网络认证与授权、密钥生成与管理和数据加密机制;最后指出了WLAN安全领域需要进一步研究的课题及802.11i目前仍存在的问题. 相似文献
105.
通过实际应用阐述了无线网络技术和在施工中的具体应用,通过无线网络来改善施工企业分布偏远、网络条件差的网络环境,为施工企业的信息化铺平网络链路。 相似文献
106.
文章介绍了基于802.11的Ad Hoc多跳网络存在的隐藏节点问题,应用ns2仿真分析了由隐藏节点等导致的TCP不稳定性现象,并提出了TCP参数优化法和MAC层协议优化来改善不稳定性,在MAC层协议优化工作方面提出了一种新的方案-DWDB算法,对基本802.11 MAC协议进行了退避算法和重传机制的修改.仿真结果表明该方案能够在提高Ad Hoc网络吞吐性能的基础上,有效地解决不稳定性问题. 相似文献
107.
The current paper presents a collection of experimental data portraying the performance achieved in the wireless setting by
several TCP-friendly congestion controls recently proposed in literature. This work is partly motivated by the consideration
that the majority of the analytical results in this area are validated by simulation, rather than by field tests. Examining
these algorithms in real environments can help verify their actual effectiveness over the wireless Internet. To reach such
goal, two representative controls among the so-called window-based TCP-friendly schemes have been implemented, namely, the
General Additive Increase Multiplicative Decrease (GAIMD) strategy, and the SQuare RooT (SQRT) binomial control; the most
representative algorithm among rate-based controls, the TCP Friendly Rate Control (TFRC), has also been considered. Their
TCP-fairness and smoothness have been comprehensively evaluated in an IEEE 802.11g Wireless Local Area Network (WLAN). The
obtained results show that the GAIMD and SQRT strategies reveal non-negligible scalability and smoothness problems, that markedly
limit their performance. It is empirically demonstrated that their “optimal” increase/decrease rules, based on TCP-Reno analytical model, cannot guarantee an adequate performance when GAIMD and SQRT compete with TCP-Sack, a de facto standard for current TCP implementations. TFRC is demonstrated to occasionally behave bewildering: properly tuning one of
its congestion control parameters and enhancing the algorithm with a flow-control mechanism result in a definitely fairer
share of bandwidth with concurrent TCP flows.
Michele Borri received the M.Sc. degree in Computer Engineering from the University of Modena and Reggio Emilia in the academic year 2001–2002
and took a specialisation in Telecommunication Engineering in 2002. His professional activity is currently balanced between
researching at the University of Modena and Reggio Emilia, and consulting as a system engineer and network architect. His
research interests focus on congestion control and multimedia services in next generation Internet. Michele Borri has been
participating to national research projects promoted by the Italian National Research Council (CNR).
Maurizio Casoni is Associate Professor in Telecommunications at the University of Modena and Reggio Emilia. He graduated with honors in Electrical
Engineering at the University of Bologna in 1991, with a grant by Telecom Italia and received the Ph.D. degree also in Electrical
Engineering from the University of Bologna, in 1995.
In 1995 he was with the Computer Science Department at Washington University in St. Louis, MO, as a research fellow where
he worked on ATM broadband switching architectures. He has studied ATM broadband switching architectures and Clos architectures
for the design of large photonic switches in the framework of the European Projects ATMOS and KEOPS. He has also investigated
the performance of 3rd generation UMTS systems. His current research interests deal with Optical Networking, mainly focusing
on Optical Burst Switching, and Satellite Networks. He currently holds the course of Interconnection Systems for undergraduate
students and the course of Switching Systems for graduate students of Telecommunications Engineering.
Maria Luisa Merani is currently an associate professor of Telecommunication Networks at the University of Modena and Reggio Emilia, Department
of Information Engineering. She is an IEEE Senior member and has served on the Technical Program Committees of several major
communication conferences (IEEE ICC, IEEE Globecom, IEEE VTC, APCC). In 2005 she has been technical program cochair of the
second IEEE International Symposium in Wireless Communication Systems. In 2007 she will be the Wireless Symposium chair of
IEEE Globecom.
At present she is involved in research on congestion control for next generation Internet and on multicast video streaming.
Her most recent research interests are related to the area of radio communications, with emphasis on performance evaluation
of mobile radio systems, 3G data networking and transport solutions for optical networks.
Maria Luisa Merani received both her M.Sc. (summa cum laude) and Ph.D. in electrical engineering from the University of Bologna,
Italy, in the academic years 1985/86 and 1991/92, respectively. In 1992 she spent one year at the Computer Science Department
of the University of California in Los Angeles, CA, USA. 相似文献
108.
We investigate how multi‐hop routing affects the goodput and throughput performances of IEEE 802.11 distributed coordination function‐based wireless networks compared with direct transmission (single hopping), when medium access control dynamics such as carrier sensing, collisions, retransmissions, and exponential backoff are taken into account under hidden terminal presence. We propose a semi‐Markov chain‐based goodput and throughput model for IEEE 802.11‐based wireless networks, which works accurately with both multi‐hopping and single hopping for different network topologies and over a large range of traffic loads. Results show that, under light traffic, there is little benefit of parallel transmissions and both single‐hop and multi‐hop routing achieve the same end‐to‐end goodput. Under moderate traffic, concurrent transmissions are favorable as multi‐hopping improves the goodput up to 730% with respect to single hopping for dense networks. At heavy traffic, multi‐hopping becomes unstable because of increased packet collisions and network congestion, and single‐hopping achieves higher network layer goodput compared with multi‐hop routing. As for the link layer throughput is concerned, multi‐hopping increases throughput 75 times for large networks, whereas single hopping may become advantageous for small networks. The results point out that the end‐to‐end goodput can be improved by adaptively switching between single hopping and multi‐hopping according to the traffic load and topology. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
109.
110.
下一代WLAN技术标准802.11ac/ad 总被引:1,自引:0,他引:1
基于IEEE802.11n标准的WLAN能够支持高达600 Mbit/s的传输速率,但在支持无线高清视频传输等高吞吐量无线数据业务时仍然会遇到瓶颈。面对这一挑战I,EEE已启动下一代WLAN技术标准802.11ac和802.11ad的制定工作,数据吞吐量将达到几个Gbit/s,能够更好地满足快速增长的市场需求。 相似文献