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PERFORMANCE OF CODED OFDM VIA VARIABLE GUARD INTERVAL 被引量:1
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作者 LiWaiyun BakirMohammed LiuJingao ZhuShouzheng 《Journal of Electronics(China)》 2005年第1期70-76,共7页
This letter presents the principles of Coded Orthogonal Frequency Division Multiplexing (COFDM) system and focuses on the effect of the Guard Interval (GI) on the systemperformance. The role of the GI parameter period... This letter presents the principles of Coded Orthogonal Frequency Division Multiplexing (COFDM) system and focuses on the effect of the Guard Interval (GI) on the systemperformance. The role of the GI parameter period to solve the problem of interferences that occur at the receiver is discussed. A new COFDM concept with a Variable GI (VGI) is proposed in order to improve the Bit Error Rate (BER) performance in the presence of multipaths with variable delays. A series of simulations have been carried out on the BER performance as a function of GI, maximum delay spread, and Signal-to-Noise Ratio (SNR), with QPSK as modulation scheme over multipath fading and Additive White Gaussian Noise (AWGN). The results show that the optimum values of the GI parameter approximately equal to the maximum delay spread, and the proposed system with VGI provides a better performance compared with the fixed length GI. 展开更多
关键词 Orthogonal Frequency Division Multiplexing(OFDM) modulation Multipathfading Variable Guard Interval(VGI) Maximum delay spread Inter-Symbol Interference(ISI) Bit Error Rate(BER)
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Joint synchronization estimation based on genetic algorithm for OFDM/OQAM systems 被引量:3
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作者 LIU Yongjin CHEN Xihong ZHAO Yu 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2020年第4期657-665,共9页
This paper investigates the problem of synchronization for offset quadrature amplitude modulation based orthogonal frequency division multiplexing(OFDM/OQAM) systems based on the genetic algorithm. In order to increas... This paper investigates the problem of synchronization for offset quadrature amplitude modulation based orthogonal frequency division multiplexing(OFDM/OQAM) systems based on the genetic algorithm. In order to increase the spectrum efficiency,an improved preamble structure without guard symbols is derived at first. On this basis, instead of deriving the log likelihood function of power spectral density, joint estimation of the symbol timing offset and carrier frequency offset based on the preamble proposed is formulated into a bivariate optimization problem. After that, an improved genetic algorithm is used to find its global optimum solution. Conclusions can be drawn from simulation results that the proposed method has advantages in the joint estimation of synchronization. 展开更多
关键词 offset quadrature amplitude modulation based orthogonal frequency division multiplexing(OFDM/OQAM) SYNCHRONIZATION joint estimation genetic algorithm
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Tone Modulation in a Passive OTDM Multiplexer for Clock Recovery from a 160 Gbit/s OTDM Signal
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作者 Tetsuya. Miyazaki Fumito Kubota 《光学学报》 EI CAS CSCD 北大核心 2003年第S1期591-592,共2页
Tone modulation in a passive OTDM multiplexer for clock recovery from a 160-Gbit/s OTDM signal by using a base-rate receiver is demonstrated. We performed synchronous demultiplexing in back-to-back arrangement and opt... Tone modulation in a passive OTDM multiplexer for clock recovery from a 160-Gbit/s OTDM signal by using a base-rate receiver is demonstrated. We performed synchronous demultiplexing in back-to-back arrangement and optical sampling after 320-km transmission. 展开更多
关键词 OTDM Tone Modulation in a Passive OTDM multiplexer for Clock Recovery from a 160 Gbit/s OTDM Signal in for from
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A full-duplex optical access system with hybrid 64/16/4QAM-OFDM downlink 被引量:2
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作者 贺超 谭泽富 +5 位作者 邵宇丰 蔡黎 蒲鹤升 朱云乐 黄思斯 刘毓 《Optoelectronics Letters》 EI 2016年第5期361-365,共5页
A full-duplex optical passive access scheme is proposed and verified by simulation, in which hybrid 64/16/4-quadrature amplitude modulation(64/16/4QAM) orthogonal frequency division multiplexing(OFDM) optical signal i... A full-duplex optical passive access scheme is proposed and verified by simulation, in which hybrid 64/16/4-quadrature amplitude modulation(64/16/4QAM) orthogonal frequency division multiplexing(OFDM) optical signal is for downstream transmission and non-return-to-zero(NRZ) optical signal is for upstream transmission. In view of the transmitting and receiving process for downlink optical signal, in-phase/quadrature-phase(I/Q) modulation based on Mach-Zehnder modulator(MZM) and homodyne coherent detection technology are employed, respectively. The simulation results show that the bit error ratio(BER) less than hardware decision forward error correction(HD-FEC) threshold is successfully obtained over transmission path with 20-km-long standard single mode fiber(SSMF) for hybrid downlink modulation OFDM optical signal. In addition, by dividing the system bandwidth into several subchannels consisting of some continuous subcarriers, it is convenient for users to select different channels depending on requirements of communication. 展开更多
关键词 downlink duplex multiplexing quadrature transmitting modulator bandwidth correction transmitter hardware
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Power distribution analysis for multiple modulation formats in an all-optical sampling wavelength division multiplexing system 被引量:2
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作者 于海 陈宏伟 +1 位作者 陈明华 谢世钟 《Chinese Optics Letters》 SCIE EI CAS CSCD 2013年第10期29-32,共4页
An optimal power distribution analysis for an all-optical sampling orthagonal frequency division multiplexing(OFDM) scheme with multiple modulation formats including diferential phase shift keyed(DPSK), diferential qu... An optimal power distribution analysis for an all-optical sampling orthagonal frequency division multiplexing(OFDM) scheme with multiple modulation formats including diferential phase shift keyed(DPSK), diferential quadrature phase shift keyed(DQPSK), and non-return-to-zero(NRZ) is proposed. The noise tolerances of different modulation formats are analyzed, and the optimal input power ratio between phase and intensity modulation formats for the best overall receiving performance is investigated under unchanged total input power. Moreover, this scheme can seamlessly coexist with the traditional WDM channel. 展开更多
关键词 OFDM DQPSK DPSK Power distribution analysis for multiple modulation formats in an all-optical sampling wavelength division multiplexing system
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Acoustic emission detection using intensity-modulated DFB fiber laser sensor 被引量:1
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作者 杨郯 宋颖 +1 位作者 张文涛 李芳 《Chinese Optics Letters》 SCIE EI CAS CSCD 2016年第12期41-44,共4页
The bonded distributed feedback(DFB) fiber laser(FL) acoustic emission sensor and the intensity response of the DFB-FL to external acoustic emissions are investigated. The dynamic sensitivity of the DFB-FL is cali... The bonded distributed feedback(DFB) fiber laser(FL) acoustic emission sensor and the intensity response of the DFB-FL to external acoustic emissions are investigated. The dynamic sensitivity of the DFB-FL is calibrated by a referenced piezoelectric receiver. In the DFB-FL we used here, the minimum detectable signal is2 × 10^(-6)m∕s at 5 kHz. Using wavelet packet technology, the collected signals are analyzed, which confirms that an intensity-modulated DFB-FL sensor can be used to detect acoustic emission signals. 展开更多
关键词 modulated receiver piezoelectric wavelet emissions packet detectable bonded multiplexing grating
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Design and analysis of an energy-efficient O-QPSK coherent IR-UWB transceiver with a 0.52° RMS phase-noise fractional synthesizer
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作者 Yutong Ying Fujiang Lin Xuefei Bai 《Journal of Semiconductors》 EI CAS CSCD 2018年第3期72-82,共11页
This paper explores an energy-efficient pulsed ultra-wideband(UWB) radio-frequency(RF) front-end chip fabricated in 0.18-μm CMOS technology, including a transmitter, receiver, and fractional synthesizer. The tran... This paper explores an energy-efficient pulsed ultra-wideband(UWB) radio-frequency(RF) front-end chip fabricated in 0.18-μm CMOS technology, including a transmitter, receiver, and fractional synthesizer. The transmitter adopts a digital offset quadrature phase-shift keying(O-QPSK) modulator and passive direct-phase multiplexing technology, which are energy-and hardware-efficient, to enhance the data rate for a given spectrum.A passive mixer and a capacitor cross-coupled(CCC) source-follower driving amplifier(DA) are also designed for the transmitter to further reduce the low power consumption. For the receiver, a power-aware low-noise amplifier(LNA) and a quadrature mixer are applied. The LNA adopts a CCC boost common-gate amplifier as the input stage, and its current is reused for the second stage to save power. The mixer uses a shared amplification stage for the following passive IQ mixer. Phase noise suppression of the phase-locked loop(PLL) is achieved by utilizing an even-harmonics-nulled series-coupled quadrature oscillator(QVCO) and an in-band noise-aware charge pump(CP) design. The transceiver achieves a measured data rate of 0.8 Gbps with power consumption of 16 m W and31.5 m W for the transmitter and the receiver, respectively. The optimized integrated phase noise of the PLL is0.52° at 4.025 GHz. 展开更多
关键词 IR-UWB O-QPSK modulation phase multiplexing transmitter receiver fractional PLL
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Experimental demonstration of 60 Gb/s optical OFDM transmissions at 1550 nm over 100 m OM1 MMF IMDD system with central launching
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作者 陈健 方玲 +4 位作者 张倩武 张俊杰 宋英雄 李迎春 汪敏 《Chinese Optics Letters》 SCIE EI CAS CSCD 2017年第6期32-35,共4页
Record-high 60 Gb/s optical orthogonal frequency division multiplexing(OFDM) transmissions over intensity modulation and direct-detection(IMDD)-based 100 m optical mode(OM1) multi-mode fiber(MMF) links are exp... Record-high 60 Gb/s optical orthogonal frequency division multiplexing(OFDM) transmissions over intensity modulation and direct-detection(IMDD)-based 100 m optical mode(OM1) multi-mode fiber(MMF) links are experimentally demonstrated, utilizing 10 GHz electro-absorption modulated laser intensity modulators at a single 1550 nm wavelength. Adaptive bit loading and a simple central launching scheme of the proposed scheme show an effective way for combating the channel fading and simplifying the system structure. It shows good potential in short reach data center interconnections. 展开更多
关键词 launching multiplexing demonstration fading modulated utilizing links transmitter offset patch
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Simultaneous generation of 3G and millimeter-wave signals using a dual-electrode MZM in ROF systems
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作者 应祥岳 徐铁峰 +3 位作者 刘太君 聂秋华 文化锋 李军 《Optoelectronics Letters》 EI 2015年第4期286-289,共4页
A novel radio-over-fiber(ROF) scheme to simultaneously generate and transmit the 3rd generation telecommunication(3G) and millimeter-wave(MMW) signals by using a single dual-electrode Mach-Zehnder modulator(MZM) is pr... A novel radio-over-fiber(ROF) scheme to simultaneously generate and transmit the 3rd generation telecommunication(3G) and millimeter-wave(MMW) signals by using a single dual-electrode Mach-Zehnder modulator(MZM) is proposed.There is no apparent nonlinearity induced by the ROF system.By employing this analog ROF signal transmission technique,highly transparent fiber-wireless convergence networks can be realized,which are ideal for multi-standard wireless system operation. 展开更多
关键词 millimeter modulator transmit apparent analog multiplexing wideband nonlinearity bandwidth transparent
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