共查询到19条相似文献,搜索用时 156 毫秒
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《无线电通信技术》2015,(5):93-96
变电站通信网络是变电站实现综合自动化的前提,变电站内部设备可划分成3个层次,其中第二层的数据和控制信息传送到与远方调度中心通信的站级PC机,该过程属于计算机通信网络的范畴,针对变电站通信网络的这个特点,将两级优先级控制轮询系统用在变电站通信网络中。提出了在站级PC通信接口(主节点)采用完全服务的轮询方式,第二层设备通信接口内部的数据缓冲区(子节点)采用门限服务的轮询方式的新模型。完全服务的优先级比门限服务的高,对新模型进行了仿真和理论计算,得出新系统的平均时延和平均排队队长与负载之间的关系、平均时延和平均排队队长与子节点数之间的关系,这些参数对于提高变电站通信网络的性能至关重要。 相似文献
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无线介质计算机通信网络中周期优先轮询服务策略的研究 总被引:1,自引:0,他引:1
本文讨论无线介质计算机通信网络中周期优先轮询服务策略,传输的排队延时分析是在中心控制器和若干外围控制器所构成的轮询模型上进行的。文中分析了引起出界和入界延时的原因、对其性能进行了计算机模拟、讨论了该方法在无线计算机网络中的应用。 相似文献
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介绍了基于电力载波智能点灯系统的设计由来和系统方案,并简要说明了其电气结构,工作原理、技术特点及应用效果。系统利用电力线作为通信媒介,由硬件电路、单片机接口电路和其它接口电路组成,采用轮询应答和载波侦听的主从通信方式,可实现对多个节点的实时集中监控。 相似文献
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本文通过对网络中轮询系统的研究,设计了基于ATM(异步转移模式)的采用轮询系统模型的BISLN(宽带综合业务局域网)原型,同时BISLN轮询系统模型已在实验室环境下实现。 相似文献
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基于nRF905和DS18B20的多路无线温度采集系统设计 总被引:1,自引:0,他引:1
设计了基于nRF905射频模块和集成温度传感器DS18B20的多路无线温度采集系统。系统每个节点均用AT89S52单片机为MCU,使用无线星型网络,在433MHz的ISM频段采用GFSK调制、地址轮询多点通信方式进行工作。样机试验结果表明,该系统抗干扰能力强,室外可靠通信距离可以达到200m以上,室内可以实现3-6层可靠通信。该系统实用性强,使用及维护方便。 相似文献
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该文提出了一种新的摹于RS-485网络通信协议运用方式,改传统的主机到从机的轮询模式为从机到主机的"轮报"模式.这种新的模式在保证RS-485网络正常通信的基础上,提高了系统的实时性. 相似文献
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提出了一种在现有媒体资产管理系统的基础上构建基于网络的分布式视频素材检索系统,通过面向服务的体系结构,以标准数据模型构建统一数据接口和协议实现异构、异地媒体资产数据检索处理,并采用轮询请求/答复的异构响应结构实现与各媒体资产管理系统的检索数据异步通信。为改善广电传媒机构媒资系统分块建设、孤岛运营现状,共享视音频媒体资源做了一种有益的尝试。 相似文献
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Designing the Next Generation of Real-Time Control, Communication, and Computations for Large Power Systems 总被引:1,自引:0,他引:1
Tomsovic K. Bakken D.E. Venkatasubramanian V. Bose A. 《Proceedings of the IEEE. Institute of Electrical and Electronics Engineers》2005,93(5):965-979
The power grid is not only a network interconnecting generators and loads through a transmission and distribution system, but is overlaid with a communication and control system that enables economic and secure operation. This multilayered infrastructure has evolved over many decades utilizing new technologies as they have appeared. This evolution has been slow and incremental, as the operation of the power system consisting of vertically integrated utilities has, until recently, changed very little. The monitoring of the grid is still done by a hierarchical design with polling for data at scanning rates in seconds that reflects the conceptual design of the 1960s. This design was adequate for vertically integrated utilities with limited feedback and wide-area controls; however, the thesis of this paper is that the changing environment, in both policy and technology, requires a new look at the operation of the power grid and a complete redesign of the control, communication and computation infrastructure. We provide several example novel control and communication regimes for such a new infrastructure. 相似文献
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Analysis of a polling system for telephony traffic with application to wireless LANs 总被引:3,自引:0,他引:3
Tao Li Logothetis D. Veeraraghavan M. 《Wireless Communications, IEEE Transactions on》2006,5(6):1284-1293
Recently, polling has been included as a resource sharing mechanism in the medium access control (MAC) protocol of several communication systems, such as the IEEE 802.11 wireless local area network, primarily to support real-time traffic. Furthermore, to allow these communication systems to support multimedia traffic, the polling scheme often coexists with other MAC schemes such as random access. Motivated by these systems, we develop a model for a polling system with vacations, where the vacations represent the time periods in which the resource sharing mechanism used is a non-polling mode. The real-time traffic served by the polling mode in our study is telephony. We use an on-off Markov modulated fluid (MMF) model to characterize telephony sources. Our analytical study and a counterpart validating simulation study show the following. Since voice codec rates are much smaller than link transmission rates, the queueing delay that arises from waiting for a poll dominates the total delay experienced by a voice packet. To keep delays low, the number of telephone calls that can be admitted must be chosen carefully according to delay tolerance, loss tolerance, codec rates, protocol overheads and the amount of bandwidth allocated to the polling mode. The effect of statistical multiplexing gain obtained by exploiting the on-off characteristics of telephony traffic is more noticeable when the impact of polling overhead is small. 相似文献
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文章经过对我国当前通信网管系统实时故障的具体研究情况开展了详细的介绍,并在此基础,主要讨论通信网管系统故障告警技术,给相关的工作人员提供一些参考资料,从而增强其对故障进行处理的效率。 相似文献
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This paper deals with a radio‐based communication network with a single radio channel shared by several data terminals for
transmissions to a single hub station. In particular, the communication system considered is a potential provider of wireless
LAN‐like services. The focus is on the capacity of combining a preemptive polling‐based multiple access scheme with a Selective
Repeat ARQ technique to counteract the effect of the nonstationary transmission channel. The nonstationary transmission channel
has been modeled as a two‐state Markov chain with parameters related to actual propagation conditions. Typical outdoor/indoor
environments have been considered. The main idea is that of making the service interruption of the preemptive polling scheme
dependent on the propagation conditions of the transmission channel by monitoring the outcome of the data packet transmission
attempts. A performance comparison clearly reveals the superiority of this preemptive polling scheme with respect to the classical
cyclic polling scheme.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
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随着卫星网络以及通信系统的逐渐研发,宽带多媒体通信卫星系统在通信领域中备受关注.宽带多媒体通信卫星系统能够实现全球无缝隙覆盖的网络互连,在通信系统研发中发挥着重要的作用.基于宽带多媒体通信卫星系统运行维护管理是保障通信卫星系统稳定运行的基础.在本文中对基于ATM的宽带多媒体通信卫星系统运维管理技术进行研究. 相似文献