共查询到20条相似文献,搜索用时 10 毫秒
1.
在无线广播网链路状态不同和丢包率高的条件下,基于机会网络编码的数据分发策略面临传输效率低和计算复杂度高的问题。针对这一问题,该文提出一种新的基于机会网络编码的加权广播重传(Weighted Opportunistic Network Coding Retransmission, WONCR)方案。该方案通过构建加权数据包分布矩阵(Weighted Packet Distribution Matrix, WPDM),在重传过程中采用新的调度算法进行编码数据包的选取,并将选取的数据包进行XOR编码后再重传。机会仿真结果表明,WONCR方案提高了传输效率,且计算开销较小,实现了无线广播网中高效、可靠的数据分发。 相似文献
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We investigate the problem of extending the network lifetime of a single broadcast session over wireless stationary ad hoc
networks where the hosts are not mobile. We define the network lifetime as the time from network initialization to the first
node failure due to battery depletion. We provide through graph theoretic approaches a polynomial-time globally optimal solution,
a variant of the minimum spanning tree (MST), to the problem of maximizing the static network lifetime. We make use of this
solution to develop a periodic tree update strategy for effective load balancing and show that a significant gain in network
lifetime over the optimal static network lifetime can be achieved. We provide extensive comparative simulation studies on
parameters such as update interval and control overhead and investigate their impact on the network lifetime. The simulation
results are also compared with an upper bound to the network lifetime.
A preliminary version of this paper appeared in IEEE ICC 2003 [35]. This research was funded in part by NSF grant ANI-0093187,
ONR award #: N00014-04-1-0479 and Collaborative Technology Alliance (CTA) from ARL under DAAD19-01-2-0011. All statements
and opinions are that of the authors and do not represent any position of the U.S government
Intae Kang received his B.S. degree in physics from Seoul National University, Seoul, Korea and M.S. degree in electrical engineering
from the Johns Hopkins University, Baltimore, MD. He is currently working toward the Ph.D. degree in the Department of Electrical
Engineering at the University of Washington, Seattle, WA.
His current research interests are in the area of ad hoc and sensor networks. In particular, he is interested in energy efficient
routing, topology control, medium access control, mobility management, and modeling and performance analysis of network protocols
using directional/smart antennas.
Radha Poovendran has been an assistant professor at the Electrical Engineering Department of the University of Washington at Seattle since
September 2000. He received his Ph.D. in Electrical Engineering from the University of Maryland, College Park in 1999. His
research interests are in the areas of applied cryptography for multiuser environment, wireless networking, and applications
of Information Theory to security. He is a recipient of Faculty Early Career Award from the National Science Foundation (2001),
Young Investigator Award from the Army Research Office (2002), Young Investigator Award from the Office of Naval Research
(2004), and the 2004 Presidential Early Career Award for Scientists and Engineers, for his research contributions in the areas
of wired and wireless multiuser security. He is also a co-recipient of the 2002 Outstanding Teaching as well as the Outstanding
Advisor Awards from the Department of Electrical Engineering of the University of Washington. 相似文献
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Vladislav R. Shteeman Dmitri L. Boiko Eli Kapon Amos A. Hardy 《Quantum Electronics, IEEE Journal of》2007,43(3):215-224
Coupled-mode theory, developed for several parallel waveguides, is extended to the case of infinite 2-D photonic crystals. Periodic boundary conditions, applied to a system of coupled identical waveguides, are used to compute the photonic band structures. This approach is shown to be more efficient than the usual numerical methods when tested on finite, but large-sized, arrays. Photonic crystals made of single-mode and multimode waveguide arrays are examined 相似文献
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本文探讨了IP多播和广播技术在PPPoE协议上的应用,并就其性能不足之处提出了一种改进方法。 相似文献
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This letter addresses a scheduling problem for wireless network coding (WNC). In our previous work, we have theoretically shown that the optimum number of nodes to be included into a network?coded packet as well as its transmission rate depends on time?varying link condition between a transmitting node and receiving nodes [1]. Based on this observation, this letter designs practical scheme which opportunistically selects scheduled nodes, packets to be coded and an employed modulation level according to time?varying channel conditions and packet length. The numerical results show that the proposed opportunistic scheduling can improve the overall throughput as compared with non?opportunistic approach. 相似文献
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Michael E. Ropp Miroslav Begovic Ajeet Rohatgi Richard Long 《Progress in Photovoltaics: Research and Applications》1997,5(1):55-67
This paper describes calculations and modeling used in the design of the photovoltaic (PV) array built on the roof of the Georgia Tech Aquatic Center, the aquatic sports venue for the 1996 Olympic and Paralympic Games. The software package PVFORM (version 3.3) was extensively utilized; because of its importance to this work, it is thoroughly reviewed here. Procedures required to adapt PVFORM to this particular installation are described. The expected behavior and performance of the system, including maximum power output, annual energy output and maximum expected temperature, are then presented, and the use of this information in making informed design decisions is described. Finally, since the orientation of the PV array is not optimal, the effect of the unoptimized array orientation on the system's performance is quantified. © 1997 John Wiley & Sons, Ltd. 相似文献
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Wireless Personal Communications - Opportunistic network coding (ONC) increases communication networks’ throughput by XORing two or more packets together. However, it has shown that ONC... 相似文献
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Vidal B. Mengual T. Ibanez-Lopez C. Marti L. 《Photonics Technology Letters, IEEE》2006,18(24):2590-2592
An optical beamformer for antenna arrays based on fiber-optical delay lines for feeding subarrays and spatial light modulators to change the radio-frequency phase of independent antenna elements is proposed. The architecture has the potential to control antenna arrays of a large number of elements. Preliminary experimental results to show the feasibility of the concept are provided 相似文献
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HFC网络前端设备的网管主要针对安装在前端机房内的有源设备,包括各种光接收机、光发射机、前置放大器等进行监测管理,对网络设备故障的及时预警、查找、处理起到至关重要的作用,改进被动抢修为主动防御,保证系统的稳定运行,为安全播出提供强有力的保障。介绍ANTEC网管系统的硬件组成和软件配置,以及网管软件的安装和使用。 相似文献
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AODV(Ad Hoc on-demand distance vector)路由协议是Ad Hoc网络中一种具有代表性的按需路由协议。传统的AODV是以“最小跳数”为参数建立和更新路由的。随着网络负荷的增加,以这种方式建立和更新路由容易引起网络中部分节点较其它节点更多地参与通信,在这些节点发生拥塞的可能性将更大,频率将更高,这会增加网络能耗,缩短网络生存时间。针对这一问题,笔者提出了通过控制拥塞对AODV进行节能改进的一种算法—Lengthen Lifetime AODV(LLAODV)。 相似文献
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针对无线Mesh网络组播中包丢失严重的问题,提出了保持包的IP层不变,而改变包的目的MAC域,进而MAC层以单播形式向组成员发送包的M2U(Multicast to Unicast) 优化解决方案.为了满足组成员增加时不影响用户的性能,提出在M2U中引入了机会路由的M2UO(Multicast to Unicast Opportunistic Routing)算法,对候选节点采用单播形式发送包,对其它节点采用组播形式发送包.在实际网络环境中的大量实验表明,优化组播减小了数据包的丢失率,提高了网络的吞吐量,具有较好的组播视频流效果. 相似文献
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随着多媒体通信业务的发展,人们对信息的需求迅速增长。同时电视、电话已普及,电脑的家庭占有率也在不断提高,传统的电视、计算机、电话采用各自的物理传输网络,传输速率低,业务内容贫乏,已不能满 相似文献
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本主要介绍了海底光缆的类型、结构和技术指标。以及海底光缆工程中的登陆点的选择、海底路由的调查、技术指标的检验和海底光缆的保护等,对海底光缆与其它传输方式比较之优势和不足也进行了分析。 相似文献
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Uplink Arrays for the Deep Space Network 总被引:2,自引:0,他引:2
Davarian F. 《Proceedings of the IEEE. Institute of Electrical and Electronics Engineers》2007,95(10):1923-1930
Deep-space communication and navigation is faced with two challenges in the future: (1) the potential retirement of the largest antennas of NASA's Deep Space Network and (2) an anticipated need for increasing ground system capacity so as to support higher data rates to and from missions operating at remote locations in the solar system, as well as in anticipation of a larger number of simultaneously flying missions. In the transmitting, or uplink, direction, one approach to increasing the effective transmitted power is to array multiple antennas. This is attractive mainly because it promises a lower construction cost than equivalent (large) single antenna systems. In addition, it has the potential for increasing the reliability of the uplink and reducing maintenance costs. This paper introduces the concept of uplink arraying by examining technological challenges and possible solutions to them. Arraying principles are presented and error sources described. The main challenge is to maintain carrier phase alignment among the antennas, and this must be done by periodic calibration. Presently, two calibration methods are being developed at the Jet Propulsion Laboratory as part of an uplink arraying demonstration effort. These methods are briefly discussed. 相似文献
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机会网络中消息冗余度动态估计的缓存管理策略 总被引:3,自引:0,他引:3
机会网络以存储-携带-转发的方式实现节点间通信,高效的节点缓存管理策略能够充分利用有限的缓存空间。该文提出了一种基于消息冗余度动态估计的自适应缓存管理机制,利用消息携带节点的活跃程度和当前网络状态下消息副本数量,预测给定消息的投递状态,节点以消息冗余程度为参数确定消息的转发以及携带优先级。结果表明,所提出的节点活跃度和消息副本数的估计方法比较准确,同时所提出的缓存管理策略能有效提高消息成功投递率,降低网络平均时延和网络负载率。 相似文献