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161.
Loss and noise figure of optical links transmitting microwave signals —e.g. for remote antennas in wireless communications — are dealt with.Conditions are rather general and include arbitrary matching conditions, shotnoise, and laser relative intensity noise. Specific and somewhat surprisingcharacteristics are derived. Among others, it is shown, that — likepassive, purely microwave systems — noise figure is not proportional toelectrical loss and it can be even lower than loss itself. Optical powershould be as low as possible — this limit is mainly determined by therequired dynamic range of the system. Loss and noise figure were measured inan experimental setup. Results of the measurements proved the theoreticalfindings rather well. Preliminary results on the transmission of 32TCM signalsover the link are briefly presented. 相似文献
162.
Zervas Evangelos Kaloxylos Alexandros Merakos Lazaros 《Mobile Networks and Applications》2001,6(2):125-135
In this paper we present a new location management protocol for wireless ATM networks, called LMCP (Location Management and Control Protocol). This protocol is based on the PNNI (Private Network-to-Network Interface) routing functionality to advertise the movement of mobile terminals within predefined areas. Moreover, LMCP uses specialized entities to store and retrieve the current location area of the mobile terminals. These entities are located in mobility enhanced switches that control the execution of mobility procedures (e.g., handovers).The main benefit from the application of LMCP is the establishment of connections that do not contain any misrouted segments. Furthermore, it requires minor modifications to the PNNI and enables its inter-working with other location management mechanisms. The protocol is compared with other similar mechanisms, and its efficiency is demonstrated by the results of an analytical model. 相似文献
163.
Acknowledgment Procedures at Radio Link Control Level in GPRS 总被引:1,自引:0,他引:1
164.
Typical formulations of thep-median problem on a network assume discrete nodal demands. However, for many problems, demands are better represented by continuous functions along the links, in addition to nodal demands. For such problems, optimal server locations need not occur at nodes, so that algorithms of the kind developed for the discrete demand case can not be used. In this paper we show how the 2-median of a tree network with continuous link demands can be found using an algorithm based on sequential location and allocation. We show that the algorithm will converge to a local minimum and then present a procedure for finding the global minimum solution. 相似文献
165.
P. Nicopolitidis G. I. Papadimitriou M. S. Obaidat A. S. Pomportsis 《International Journal of Communication Systems》2005,18(7):657-669
A Carrier‐sense‐assisted adaptive learning MAC protocol for wireless LANs, capable of operating efficiently in bursty traffic wireless networks with unreliable channel feedback, is introduced. According to the proposed protocol, the mobile station that is granted permission to transmit is selected by means of learning automata. At each station, the learning automaton takes into account the network feedback information in order to update the choice probability of each mobile station. The proposed protocol utilizes carrier sensing in order to reduce the collisions that are caused by different decisions at the various mobile stations due to the unreliable channel feedback. Simulation results show satisfactory performance of the proposed protocol compared to similar MAC protocols. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
166.
We prove that any mapping class on a compact oriented surface with non-empty boundary can be made pseudo-Anosov and right-veering
after a sequence of positive stabilizations.
相似文献
167.
对美国高通公司推出的MeidaFLO进行了介绍.特别就其FLO空中接口技术与另一种主流技术DVB-H进行了比较.作为一种全新的无线多媒体传输技术,FLO创新的一体化解决方案、优化编码方式、分层调制与手机高度集成等特性使得其在实现多媒体传输方面拥有其它技术无法比拟的优越性. 相似文献
168.
本文综述了当前几种发展极为迅速的宽带固定无线接入技术,讨论了其演变过程及在国内的发展现状,并总结了无线接入在未来的主要发展趋势。 相似文献
169.
Gass John H. Pursley Michael B. Russell Harlan B. Wysocarski Jeffrey S. 《Wireless Networks》2001,7(5):487-495
An energy-efficient adaptive-transmission protocol for mobile frequency-hop spread-spectrum wireless communication networks is described and evaluated. The purpose of the protocol is to permit each of the mobile terminals to adjust its transmitter power and code rate to match the characteristics of the time-varying communication links in the network. The proposed adaptive-transmission protocol bases its choice of transmission parameters on a very simple form of side information that is easy to obtain in a FH communication receiver. The performance of the adaptive-transmission protocol is evaluated for networks in which each communication link may have a time-varying propagation loss and intermittent partial-band interference. Our results demonstrate that the adaptive-transmission protocol can improve the utility of a link and reduce energy consumption by adjusting the transmission parameters in response to changes in the side information. 相似文献
170.
一种新型校园社区网建设方案 总被引:1,自引:0,他引:1
提出了一套校园网建设方案,通过该方案的实现,使教职员工可用一张201卡进行语音通信和上网.极大地方便了师生的工作和学习;同时通过灵活的计费策略,很好地解决了学生上网对网络资源和宽带过渡占用的问题.保证了网络资源得以充分的利用. 相似文献