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A SCHEDULING ALGORITHM USING COMPENSATING ROUND ROBIN IN PACKET-SWTICHING broadband networks

Journal of Electronics(China) 2002年第2期19卷 139-145页

作者： Lan Julong Wang Binqiang Li Ou Wu Jiangxing(National Digital Switching System Eng. & Technological Research Center.Zhengzhou 450002) National Digital Switching System Eng. & Technological Research Center Zhengzhou 450002

A new approximation of fair queuing called Compensating Hound Robin (CRR) is presented in this paper. The algorithm uses packet-by-packet scheduler with a compensating measure. It achieves good fairness in terms of throughput, requires only O( I) time complexity to process a packet, and is simple enough to be implemented in hardware. After the performances are analyzed, the fairness and packet loss rate of the algorithm are simulated. Simulation results show that the CRR can effectively isolate the effects of contending .sources.

关键词： broadband networks Round robin Scheduling Bandwidth allocation Queuing

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Widely tunable all-optical wavelength converter based on four-wave mixing using two orthogonally polarized pumps

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Chinese Optics Letters 2004年第6期2卷 351-353页

作者：王肇颖李智勇葛春风胡智勇贾东方李世忱 College of Precision Instrument and Opto-Electronics Engineering Tianjin University Key Laboratory of Opto-Electronics Information and Technical Science (Tianjin University) Ministry of Education Tianjin 300072 Key Laboratory of Opto-Electronics Information and Technical Science (Tianjin University) Ministry of Education Tianjin 300072he principle of broad-band orthogonal-pump (BOP) four-wave mixing in semiconductor optical amplifiers is analyzed in theory. The conversion efficiency reduces rapidly as the detuning of wavelength between the signal and pump increase which can be solved by introducing a BOP method. The constant conversion efficiency and signal-to-noise ratio are obtained over a large wavelength detuning range. The wavelength conversion efficiency with variation smaller than 3.88 dB over 52-nm range has been experimentally demonstrated by using BOP with the 10-GHz output of distributed feedback/electro-absorption modulator as signal. Conventional single-pump scheme is also performed for comparison and the experimental results fit well with the theory.

The principle of broad-band orthogonal-pump (BOP) four-wave mixing in semiconductor optical amplifiers is analyzed in theory. The conversion efficiency reduces rapidly as the detuning of wavelength between the signal and pump increase which can be solved by introducing a BOP method. The constant conversion efficiency and signal-to-noise ratio are obtained over a large wavelength detuning range. The wavelength conversion efficiency with variation smaller than 3.88 dB over 52-nm range has been experimentally demonstrated by using BOP, with the 10-GHz output of distributed feedback/electro-absorption modulator as signal. Conventional single-pump scheme is also performed for comparison and the experimental results fit well with the theory.

关键词： broadband networks Light amplifiers Signal to noise ratio Tuning Wavelength division multiplexing

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A novel repetition space-time coding scheme for mobile FSO systems

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Optoelectronics Letters 2015年第2期11卷 125-129页

作者：黎明曹阳李书明杨绍文 Department of Information Engineering Hubei Normal University School of Electronic Information & Automation Chongqing University of Technology

Considering the influence of more random atmospheric turbulence, worse pointing errors and highly dynamic link on the transmission performance of mobile multiple-input multiple-output （MIMO） free space optics （FSO） communica- tion systems, this paper establishes a channel model for the mobile platform. Based on the combination of Alamouti space-time code and time hopping ultra-wide band （TH-UWB） communications, a novel repetition space-time coding （RSTC） method for mobile 2x2 free-space optical communications with pulse position modulation （PPM） is devel- oped. In particular, two decoding methods of equal gain combining （EGC） maximum likelihood detection （MLD） and correlation matrix detection （CMD） are derived. When a quasi-static fading and weak turbulence channel model are considered, simulation results show that whether the channel state information （CSI） is known or not, the coding sys- tem demonstrates more significant performance of the symbol error rate （SER） than the uncoding. In other words, transmitting diversity can be achieved while conveying the information only through the time delays of the modulated signals transmitted from different antennas. CMD has almost the same effect of signal combining with maximal ratio combining （MRC）. However, when the channel correlation increases, SER performance of the coding 2×2 system de- grades significantly.

关键词： Atmospheric turbulence broadband networks Channel capacity Channel state information Codes (symbols) Communication channels (information theory) Fading channels Iterative decoding Maximum likelihood MIMO systems Optical communication Pulse position modulation Radio communication Random errors Signal detection Signal encoding Space time adaptive processing Telecommunication networks Time delay Ultra wideband (UWB)

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