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101.
A. Fielding 《Optics & Laser Technology》1986,18(3)
A single mode 3 dB fused coupler, to be used as a redundant laser combiner in the submerged repeater of an undersea optical fibre transmission system, is described. The fabrication and package design of the component for this high reliability application is discussed, and the results of a wide range of environmental tests are given. 相似文献
102.
Diversity-and-multiplexing tradeoff and throughput of superposition coding relaying strategy 总被引:1,自引:1,他引:0
While the Network Coding cooperative relaying (NC-relaying) has the merit of high spectral ef-ficiency, Superposition Coding relaying (SC-relaying) has the merit of high throughput. In this paper, a novel concept, coded cooperative relaying, is presented, which is a unified scheme of the NC-relaying and SC-relaying. For the SC-relaying strategy which can be considered one-way coded relaying scheme with multi-access channel, the close-form solution of the outage probabilities of the basic signal and additional signal are obtained firstly. Secondly, the Diversity-and-Multiplexing Tradeoff (DMT) characteristics of ba-sic signal and additional signal are investigated entirely as well as the optimal close-form solutions. The compared numerical analysis shows the evaluation error of throughput based on the close-form solution is about 0.15 nats, which is within the acceptable error range. Due to the mutual effect between the both source signals, the available maximal values of the two multiplexing gains are less than 1. 相似文献
103.
This paper proposes a new structure of decision feedback equalizer that exploits the cyclostationary properties of digitally
modulated signals to mitigate interference. In the proposed structure, the forward filter of the conventional DFE is replaced
by a cyclic filter. It is assumed that the desired and the interference signals use some mutually different signaling attributes,
for example symbol rates, centre frequency etc. The resulting structure is evaluated in the presence of up to six strong interfering
signals, a scenario that is typically found in wireless cellular systems. The proposed structure provides performance gains
for some modulation formats but it reduces to the conventional DFE for other signal formats. 相似文献
104.
105.
ZHANG Zu-fan 《中国邮电高校学报(英文版)》2005,12(3)
1 Introduction The performance analysis of co-channel interferenceincellular systems has been actively researched in the lastfewyears , due to the rapid deployment and success ofsuch systems , and because of the scarce bandwidthwhich calls for very careful design tools in order to uti-lizeit most efficiently.Signal transmission over a mobilechannel often suffers fromshadowing effect ,causing byobstacles in the radio propagation, such as the build-ings .In a cellular mobile system,the problemis… 相似文献
106.
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
107.
近年来,移动蜂窝通信的发展速度可谓骇世惊人。1990年,移动用户有1100万,到1998年底达到了3亿多个。据预测,在今后10年中移动蜂窝用户数将超过固定电话。本文研究了全球移动蜂窝通信的发展状况,就技术革命、服务提供、管制、接入、价格以及发展前途等方面进行了详细的论述。 相似文献
108.
A. M. Bck D. C. Carpenter A. P. Gallois 《International Journal of Satellite Communications and Networking》1990,8(2):111-115
The requirement for a model of FM-TV spectra in the planning procedure of satellite communication systems is introduced. Based on long-term measurements of live TV channels, statistical properties of video spectra are examined and probability distributions for the luminance and chrominance components are proposed. The spectrum of the frequency-modulated signal is then derived, and signal distortion due to bandlimiting is calculated. Adjacent and cochannel interference effects are also investigated, with example cases illustrating influences of subcarrier loading and energy dispersion. The proposed model, which describes FM-TV spectra in terms of random variables, makes it possible to examine relative effects of system parameters, and will, therefore, be of benefit in the planning of new satellite services. 相似文献
109.
陈如明 《电信工程技术与标准化》2000,(5):5-10
本文论述了当前全球无线通信发展中的六大新走势,即市场走势规模化,网络走势全球化,业务走势数据化,技术走势宽带化,接入走势普遍化以及知识走势经济化。 相似文献
110.
S. V. Pappu 《Optics & Laser Technology》1989,21(5)
A state-of-the-art review on holographic optical elements (HOE) is presented in two parts. In Part I a conceptual overview and an assessment of the current status on the design of HOE have been included. It is pointed out that HOE development based on the use of squeezed light, speckle, non-linear recording, comparative studies between optics and communication approaches, are some of the promising directions for future research in this vital area of photonics. 相似文献