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Optical fiber acoustic sensing multiplexing system based on TDM/SFDM

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Chinese Optics Letters 2015年第1期13卷 6-9页

作者：谢杰辉王付印潘瑶胡正良胡永明 College of Optoelectronic Science and Engineering National University of Defense Technology

We propose a system of time-division multiplexing （TDM） and spatial frequency-division multiplexing （SFDM）. Extrinsic Fabry Perot interferometric sensors are applied to detect weak acoustic signals. The broadband source is employed, the light from it is modulated by a pulse signal sequence and is efficiently amplified by semiconductor optical amplifiers. Experimental results show that the equivalent noise pressure spectrum level is -97.2 dB re 1 rad/√Hz below 1250 Hz, and the cross talk between two sensors in one TDM channel is -32.7 dB with a cavity length difference of 60 μm. The number of sensors in this multiplexing system can theoretically reach 160.

关键词： Crosstalk Fabry Perot interferometers frequency division multiplexing Light amplifiers multiplexing multiplexing equipment Optical fibers Semiconductor optical amplifiers

Direct-detection OFDM-QPSK system performance improvement enabled by DFT spread and receiver-based ISFA algorithm

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Chinese Optics Letters 2016年第5期14卷 34-37页

作者：苏婕李欣颖余建军 Education Ministry Key Laboratory of Electromagnetic Wave Information Science Information Science and Engineering SchoolFudan University

We experimentally demonstrate a direct-detection orthogonal-frequency-division-multiplexing quadraturephase-shift-keying（OFDM-QPSK） system that is capable of delivering a 32 Gbaud OFDM-QPSK signal over7 km single-mode fiber-28（SMF-28）. Intra-symbol frequency-domain averaging（ISFA） channel response estimation is applied to suppress in-band noise,while discrete Fourier transform-spread（DFT-spread） is used to reduce the peak-to-average power ratio（PAPR） of the transmitted OFDM signal. With the aid of ISFA-based channel estimation and PAPR reduction enabled by DFT-spread,the bit-error ratio of the system after 7 km SMF-28 transmission can be improved from 2×10^-3 to error-free when the received optical power is -8.5 d Bm.

关键词： Algorithms Channel estimation Discrete Fourier transforms frequency division multiplexing frequency domain analysis frequency estimation Quadrature phase shift keying Signal detection Single mode fibers

Adaptive frequency domain pre-equalization for white-LED nonlinearity in OFDM-based visible light communication systems

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Chinese Optics Letters 2015年第7期13卷 101-104页

作者：张汝岐李建锋黄治同纪越峰 State Key Laboratory of Information Photonics and Optical Communications Beijing University of Posts and Telecommunications

In visible light communication, orthogonal frequency division multiplexing （OFDM） is an effective approach to improve the system speed. However, the nonlinearity of the light-emitting diode （LED） suppresses the trans- mission performance. The low-frequency part of the transmitted signal from LED suffers more from nonlinearity. Therefore, a pre-equalization scheme which suppresses the low frequency part of the OFDM signal and enhances the high frequency part can decrease the impact of LED nonlinearity. The experimental results show that the bit-error rate performance is largely enhanced by the pre-compensation.

关键词： Bit error rate Error compensation frequency division multiplexing frequency domain analysis Light Optical communication Orthogonal frequency division multiplexing Visible light communication

Design and Analysis of a Coded Multi-Carrier CDMA System

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The Journal of China Universities of Posts and Telecommunications 2001年第3期8卷 57-61页

作者： ZHENGBao-yu FANGJian DepartmentofInformationEngineering NanjingUniversityofPostsandTelcommunicationsNanjing210003P.R.China DepartmentofInformationEngineering NanjingUniversityofPostsandTelcommunicationsNanjing210003

The multi-carrier code division multiple access (MC-CDMA) system is extended to the coded MC-CDMA system. This system combine the channel error correcting coding (ECC) with MC-CDMA systems, thus sufficiently exploiting the excellent performance of ECC (especially Turbo code) under low SNR. The BER performance of the system in different channels is analyzed, and the simulation results are given.

关键词： frequency division multiplexing code division multiple access error-correcting coding