Oscillator phase noise is one of the bottlenecks that limits the self-interference(SI)cancellation capability of full-duplex systems.In this paper,we propose a method for the suppression of common phase error(CPE)and ...Oscillator phase noise is one of the bottlenecks that limits the self-interference(SI)cancellation capability of full-duplex systems.In this paper,we propose a method for the suppression of common phase error(CPE)and intercarrier interference(ICI)induced by the phase noise in full-duplex orthogonal frequency division multiplexing(OFDM)systems.First,we regard the effect of CPE as a portion of the SI channel and perform estimation,reconstruction and elimination in the time domain.Then,the ICI signal is estimated and suppressed in the frequency domain.Additionally,by analysing the performance of proposed algorithm,we further develop an iterative mechanism to reduce the parameter estimation error and improve SI cancellation capability.Simulation results show that the proposed method has a significant SI cancellation capability improvement over the traditional SI cancellation schemes.展开更多
This paper addresses a computationally compact and statistically optimal joint Maximum a Posteriori(MAP)algorithm for channel estimation and data detection in the presence of Phase Noise(PHN)in iterative Orthogonal Fr...This paper addresses a computationally compact and statistically optimal joint Maximum a Posteriori(MAP)algorithm for channel estimation and data detection in the presence of Phase Noise(PHN)in iterative Orthogonal Frequency Division Multiplexing(OFDM)receivers used for high speed and high spectral efficient wireless communication systems.The MAP cost function for joint estimation and detection is derived and optimized further with the proposed cyclic gradient descent optimization algorithm.The proposed joint estimation and detection algorithm relaxes the restriction of small PHN assumptions and utilizes the prior statistical knowledge of PHN spectral components to produce a statistically optimal solution.The frequency-domain estimation of Channel Transfer Function(CTF)in frequency selective fading makes the method simpler,compared with the estimation of Channel Impulse Response(CIR)in the time domain.Two different time-varying PHN models,produced by Free Running Oscillator(FRO)and Phase-Locked Loop(PLL)oscillator,are presented and compared for performance difference with proposed OFDM receiver.Simulation results for joint MAP channel estimation are compared with Cramer-Rao Lower Bound(CRLB),and the simulation results for joint MAP data detection are compared with“NO PHN"performance to demonstrate that the proposed joint MAP estimation and detection algorithm achieve near-optimum performance even under multipath channel fading.展开更多
An oscillator(OSC)with a metamaterial resonator based on high-Q is designed to improve the phase noise in Kband.The proposed metamaterial resonator is a lattice structure resonator(LSR)that is designed to be high-Q by...An oscillator(OSC)with a metamaterial resonator based on high-Q is designed to improve the phase noise in Kband.The proposed metamaterial resonator is a lattice structure resonator(LSR)that is designed to be high-Q by a strong coupling of E-field at the resonance frequency.Thus the output of OSC is about 12.5dBm at the f0.The phase noise is 109.477dBc/Hz at 100kHz offset frequency.展开更多
A low-phase-noise CMOS voltage-controlled oscillator( VCO) with zero-bias scheme and multi-stage filtering is presented. Sharing ground w ith fully integrated loop filter,the PM OS-only VCO achieves a zero-bias scheme...A low-phase-noise CMOS voltage-controlled oscillator( VCO) with zero-bias scheme and multi-stage filtering is presented. Sharing ground w ith fully integrated loop filter,the PM OS-only VCO achieves a zero-bias scheme,w hich prevents tuning line noise from disturbing VCO output common-mode voltage and hence minimizes phase noise caused by nonlinear C-V characteristic of varactors. Top-biased current source is optimized by multi-stage filtering to reduce 1/f flicker and thermal noise. Fabricated in TSM C 180 nm CM OS process,the proposed VCO exhibits a measured oscillation frequency of 0.85 ~ 1.45 GHz,w ith a phase noise of-121.8 ^-131.3 dBc/Hz @ 1MHz offset over the w hole band. Pow er consumption is 3.8 ~ 6.3 mW from a 1.8 V supply.展开更多
In this paper, a novel voltage controlled oscillator (VCO) with low phase noise, low power consumption and wide tuning range in the industrial, scientific and medical (ISM) band is proposed for communication systems a...In this paper, a novel voltage controlled oscillator (VCO) with low phase noise, low power consumption and wide tuning range in the industrial, scientific and medical (ISM) band is proposed for communication systems applications. For improving the phase noise, filtering technique is used and VCO is designed with TSMC CMOS 0.18 μm technology and the power supply is 1.5 V. The simulation results with advanced design system (ADS) shows that phase noise in 1 MHz offset frequency from the carrier is -122 dBc/Hz and tuning range is 2 to 2.8 GHz. The power consumption of the core is 2.49 mW.展开更多
We propose a photonic-assisted single system for measuring the frequency and phase noise of microwave signals in a large spectral range. Both the frequency and phase noise to be measured are extracted from the phase d...We propose a photonic-assisted single system for measuring the frequency and phase noise of microwave signals in a large spectral range. Both the frequency and phase noise to be measured are extracted from the phase difference between the signal under testing and its replica delayed by a span of fiber and a variable optical delay line(VODL). The system calibration, frequency measurement, and phase noise measurement are performed by adjusting the VODL at different working modes. Accurate frequency and phase noise measurement for microwave signals in a large frequency range from 5 to 50 GHz is experimentally demonstrated.展开更多
A low phase noise millimeter-wave(MMW) signal generator is proposed and experimentally demonstrated with a C-band passively Fabry-Pérot(F-P) quantum dot mode-locked laser. A novel method is proposed to generate l...A low phase noise millimeter-wave(MMW) signal generator is proposed and experimentally demonstrated with a C-band passively Fabry-Pérot(F-P) quantum dot mode-locked laser. A novel method is proposed to generate low phase noise MMW signal, which is simply based on a commercial off-the-shelf dual-driven Li Nb O3 Mach-Zehnder modulator and a passively F-P quantum dot mode-locked laser. MMW signal with the frequency of 30 GHz, 45 GHz and 90 GHz respectively is obtained experimentally. Single-sideband phase noise of the 30 GHz and 45 GHz MMW signal is-112 d Bc/Hz and-106 d Bc/Hz at an offset of 1 k Hz, respectively. The linewidth of the 30 GHz and 45 GHz MMW signal is about from 225 Hz and 239 Hz. This is considered a very simple MMW generator with a quasi-tunable broadband and ultra-low phase noise.展开更多
Intensity noise including Mode Partition Noise (MPN) and Mode Hopping Noise (MHN), and Phase/Frequency Noise Spectrum (FNS) are calculated for a two-mode semiconductor laser. RIN is derived considering of MPN and MHN ...Intensity noise including Mode Partition Noise (MPN) and Mode Hopping Noise (MHN), and Phase/Frequency Noise Spectrum (FNS) are calculated for a two-mode semiconductor laser. RIN is derived considering of MPN and MHN effect.展开更多
We demonstrate coherent optical frequency dissemination over a distance of 972 km by cascading two spans where the phase noise is passively compensated for.Instead of employing a phase discriminator and a phase lockin...We demonstrate coherent optical frequency dissemination over a distance of 972 km by cascading two spans where the phase noise is passively compensated for.Instead of employing a phase discriminator and a phase locking loop in the conventional active phase control scheme,the passive phase noise cancellation is realized by feeding double-trip beat-note frequency to the driver of the acoustic optical modulator at the local site.This passive scheme exhibits fine robustness and reliability,making it suitable for long-distance and noisy fiber links.An optical regeneration station is used in the link for signal amplification and cascaded transmission.The phase noise cancellation and transfer instability of the 972-km link is investigated,and transfer instability of 1.1×10^(-19)at 10^(4)s is achieved.This work provides a promising method for realizing optical frequency distribution over thousands of kilometers by using fiber links.展开更多
We have demonstrated a distributed vibration sensor based on phase-sensitive optical time-domain reflectometer (φ-OTDR) system exhibiting immunity to the laser phase noise. Two laser sources with different linewidth ...We have demonstrated a distributed vibration sensor based on phase-sensitive optical time-domain reflectometer (φ-OTDR) system exhibiting immunity to the laser phase noise. Two laser sources with different linewidth and phase noise levels are used in the φ-OTDR system, respectively. Based on the phase noise power spectrum density of both lasers, the laser phase is almost unchanged during an extremely short period of time, hence, the impact of phase noise can be suppressed effectively through phase difference between the Rayleigh scattered light from two adjacent sections of the fiber which define the gauge length. Based on the phase difference method, the external vibration can be located accurately at 41.01 km by the(φ-OTDR system incorporating these two lasers. Meanwhile, the average signal-to-noise ratio (SNR) of the retrieved vibration signal by using Laser I is found to be -37.7 dB, which is comparable to that of -37.5 dB by using Laser II although the linewidth and the phase noise level of the two lasers are distinct. The obtained results indicate that the phase difference method can enhance the performance of(φ-OTDR system with laser phase-noise immunity for distributed vibration sensing, showing potential application in oil-gas pipeline monitoring, perimeter security, and other fields.展开更多
The fiber nonlinearity and phase noise(PN)are the focused impairments in the optical communication system,induced by high-capacity transmission and high laser input power.The channels include high-capacity transmissio...The fiber nonlinearity and phase noise(PN)are the focused impairments in the optical communication system,induced by high-capacity transmission and high laser input power.The channels include high-capacity transmissions that cannot be achieved at the end side without aliasing because of fiber nonlinearity and PN impairments.Thus,addressing of these distortions is the basic objective for the 5G mobile network.In this paper,the fiber nonlinearity and PN are investigated using the assembled methodology of millimeter-wave and radio over fiber(mmWave-RoF).The analytical model is designed in terms of outage probability for the proposed mmWave-RoF system.The performance of mmWave-RoF against fiber nonlinearity and PN is studied for input power,output power and length using peak to average power ratio(PAPR)and bit error rate(BER)measuring parameters.The simulation outcomes present that the impacts of fiber nonlinearity and PNcan be balanced for a huge capacity mmWave-RoF model applying input power carefully.展开更多
Gain-parameter-dependent transfer functions and phase-noise performances in a mode-locked Yb-doped fiber laser are measured in this study.It is discovered that the corner frequency in the amplitude and phase domains i...Gain-parameter-dependent transfer functions and phase-noise performances in a mode-locked Yb-doped fiber laser are measured in this study.It is discovered that the corner frequency in the amplitude and phase domains is determined by the absorption coefficient of the gain fiber,when the total absorption and other cavity parameters are fixed.This shows that an oscillator using gain fiber with higher dopant concentration accumulates more phase noise.Furthermore,we present net cavity dispersion-dependent transfer functions to verify the effect of dispersion management on the frequency response.We derive a guideline for optimizing mode-locked fiber laser design to achieve low phase noise and timing jitter.展开更多
In this paper,we describe an optical path stabilization method in order to keep the phase of the clock laser fixed during the interrogation.The phase noise along the optical path of the clock laser is extracted from t...In this paper,we describe an optical path stabilization method in order to keep the phase of the clock laser fixed during the interrogation.The phase noise along the optical path of the clock laser is extracted from the heterodyne beat signals.Then an acousto-optic modulator(AOM)driven by direct digital synthesizer(DDS)receives a feedback signal to cancel the phase noise.The experimental results show that our system can effectively suppress additional phase noise.The fractional frequency instability is dropped to 1.76×10^-17/τ at 1 s,which is improved by two orders of magnitude than before.In the case of Rabi excitation with a pulse duration T=50 ms,frequency shift is 7.9 mHz due to the feedback system relock process.For phase noise from different frequency,the system has a good suppression effect on low frequency phase noise.展开更多
A 19 mW highly integrated GPS receiver with a ΣΔ fractional-N synthesizer is presented in this paper.Fractional-N frequency synthesizer architecture was adopted in this work, to provide more degrees of freedom in th...A 19 mW highly integrated GPS receiver with a ΣΔ fractional-N synthesizer is presented in this paper.Fractional-N frequency synthesizer architecture was adopted in this work, to provide more degrees of freedom in the synthesizer design.A high linearity low noise amplifier(LNA) is integrated into the chip.The radio receiver chip was fabricated in a 0.18 μm complementary metal oxide semiconductor(CMOS) process and packaged in a 48-pin 2 mm×2 mm land grid array chip scale package.The chip consumes 19 mW(LNA1 excluded) and the LNA1 6.3 mW.Measured performances are:noise figure<2 dB, channel gain=108 dB(LNA1 included), image rejection>36 dB, and-108 dBc/Hz @ 1 MHz phase noise offset from the carrier.The carrier noise ratio(C/N) can reach 41 dB at an input power of-130 dBm.The chip operates over a temperature range of-40, 120 °C and ±5% tolerance over the CMOS technology process.展开更多
One of the major limitations of using Interferometric Synthetic Aperture Radar(InSAR)in time series analysis is the low-phase coherence associated with rough terrain and vegetated areas,which results in limited spatia...One of the major limitations of using Interferometric Synthetic Aperture Radar(InSAR)in time series analysis is the low-phase coherence associated with rough terrain and vegetated areas,which results in limited spatial coverage in such regions.Permanent scatterers technique was introduced to overcome this limitation using time-series analysis.However,identifying major scatterers within a pixel requires the single-looked pixels oversampling which can be a demanding process especially with large interferometric stacks and vast study areas.Therefore,using multilooked temporal coherent pixels was proposed to increase processing efficiency and coverage by utilizing distributed targets,but this technique may exclude pixels with reliable phase returns because of their temporal varying neighboring pixels.In this paper,we propose a technique to identify multilooked temporal stable pixels with reliable phase returns independent of their neighboring pixels.We conduct a simulation analysis to relate the spatial coherence of a pixel with its expected temporal correlation in the time series analysis module.We found that a liberal temporal correlation threshold of 0.53 in multilooked pixels stack is equivalent to a spatial coherence threshold of 0.2 when using number of looks of 9,which is considered acceptable in temporal coherent pixels,in terms of phase standard deviation.Applying these findings to study the 2011 Tohoku earthquake in the northeastern part of Japan resulted in increasing the number of usable pixels and spatial coverage index by nearly 50.4%and 36.8%,respectively,compared to the temporal coherent pixels.Furthermore,we propose an approach to integrate GPS observations with InSAR time series analysis,which resulted in deformation maps of the megathrust 2011 Tohoku earthquake with mean RMSE of 11.4 mm and a correlation of 98%in comparison to GPS observations.展开更多
A 0.20–2.43 GHz fractional-N frequency synthesizer is presented for multi-band wireless communication systems,in which the scheme adopts low phase noise voltage-controlled oscillators(VCOs)and a charge pump(CP)with r...A 0.20–2.43 GHz fractional-N frequency synthesizer is presented for multi-band wireless communication systems,in which the scheme adopts low phase noise voltage-controlled oscillators(VCOs)and a charge pump(CP)with reduced current mismatch.VCOs that determine the out-band phase noise of a phase-locked loop(PLL)based frequency synthesizer are optimized using an automatic amplitude control technique and a high-quality factor figure-8-shaped inductor.A CP with a mismatch suppression architecture is proposed to improve the current match of the CP and reduce the PLL phase errors.Theoretical analysis is presented to investigate the influence of the current mismatch on the output performance of PLLs.Fabricated in a TSMC 0.18-μm CMOS process,the prototype operates from 0.20 to 2.43 GHz.The PLL synthesizer achieves an in-band phase noise of-96.8 dBc/Hz and an out-band phase noise of-122.8 dBc/Hz at the 2.43-GHz carrier.The root-mean-square jitter is 1.2 ps under the worst case,and the measured reference spurs are less than-65.3 dBc.The current consumption is 15.2 mA and the die occupies 850μm×920μm.展开更多
Wireless backhaul is considered to be the key part of the future wireless network with dense small cell traffic and high capacity demand.In this paper,we focus on the design of a high spectral efficiency line-of-sight...Wireless backhaul is considered to be the key part of the future wireless network with dense small cell traffic and high capacity demand.In this paper,we focus on the design of a high spectral efficiency line-of-sight(LoS)multiple-input multiple-output(MIMO)system for millimeter wave backhaul using dual-polarized frequency division duplex(FDD).High spectral efficiency is very challenging to achieve for the system due to various physical impairments such as phase noise(PHN),timing offset(TO)as well as the poor condition number of the LoS MIMO.In this paper,we propose a holistic solution containing TO compensation,PHN estimation,precoder/decorrelator optimization of the LoS MIMO for wireless backhaul,and the interleaving of each part.We show that the proposed solution has a robust performance with end-to-end spectral efficiency of 60 bit/s/Hz for 88 MIMO.展开更多
基金supported by National Key R&D Program of China under Grant No.2020YFB1805102。
文摘Oscillator phase noise is one of the bottlenecks that limits the self-interference(SI)cancellation capability of full-duplex systems.In this paper,we propose a method for the suppression of common phase error(CPE)and intercarrier interference(ICI)induced by the phase noise in full-duplex orthogonal frequency division multiplexing(OFDM)systems.First,we regard the effect of CPE as a portion of the SI channel and perform estimation,reconstruction and elimination in the time domain.Then,the ICI signal is estimated and suppressed in the frequency domain.Additionally,by analysing the performance of proposed algorithm,we further develop an iterative mechanism to reduce the parameter estimation error and improve SI cancellation capability.Simulation results show that the proposed method has a significant SI cancellation capability improvement over the traditional SI cancellation schemes.
文摘This paper addresses a computationally compact and statistically optimal joint Maximum a Posteriori(MAP)algorithm for channel estimation and data detection in the presence of Phase Noise(PHN)in iterative Orthogonal Frequency Division Multiplexing(OFDM)receivers used for high speed and high spectral efficient wireless communication systems.The MAP cost function for joint estimation and detection is derived and optimized further with the proposed cyclic gradient descent optimization algorithm.The proposed joint estimation and detection algorithm relaxes the restriction of small PHN assumptions and utilizes the prior statistical knowledge of PHN spectral components to produce a statistically optimal solution.The frequency-domain estimation of Channel Transfer Function(CTF)in frequency selective fading makes the method simpler,compared with the estimation of Channel Impulse Response(CIR)in the time domain.Two different time-varying PHN models,produced by Free Running Oscillator(FRO)and Phase-Locked Loop(PLL)oscillator,are presented and compared for performance difference with proposed OFDM receiver.Simulation results for joint MAP channel estimation are compared with Cramer-Rao Lower Bound(CRLB),and the simulation results for joint MAP data detection are compared with“NO PHN"performance to demonstrate that the proposed joint MAP estimation and detection algorithm achieve near-optimum performance even under multipath channel fading.
文摘An oscillator(OSC)with a metamaterial resonator based on high-Q is designed to improve the phase noise in Kband.The proposed metamaterial resonator is a lattice structure resonator(LSR)that is designed to be high-Q by a strong coupling of E-field at the resonance frequency.Thus the output of OSC is about 12.5dBm at the f0.The phase noise is 109.477dBc/Hz at 100kHz offset frequency.
基金supported by the National Natural Science Foundation of China(grant:61234007)the sub-project of the Very Large Scale Integrated Circuits Manufacturing Equipment and Complete Technology(No.2 National Major Projects of China)(No.:2013ZX02502-001)
文摘A low-phase-noise CMOS voltage-controlled oscillator( VCO) with zero-bias scheme and multi-stage filtering is presented. Sharing ground w ith fully integrated loop filter,the PM OS-only VCO achieves a zero-bias scheme,w hich prevents tuning line noise from disturbing VCO output common-mode voltage and hence minimizes phase noise caused by nonlinear C-V characteristic of varactors. Top-biased current source is optimized by multi-stage filtering to reduce 1/f flicker and thermal noise. Fabricated in TSM C 180 nm CM OS process,the proposed VCO exhibits a measured oscillation frequency of 0.85 ~ 1.45 GHz,w ith a phase noise of-121.8 ^-131.3 dBc/Hz @ 1MHz offset over the w hole band. Pow er consumption is 3.8 ~ 6.3 mW from a 1.8 V supply.
文摘In this paper, a novel voltage controlled oscillator (VCO) with low phase noise, low power consumption and wide tuning range in the industrial, scientific and medical (ISM) band is proposed for communication systems applications. For improving the phase noise, filtering technique is used and VCO is designed with TSMC CMOS 0.18 μm technology and the power supply is 1.5 V. The simulation results with advanced design system (ADS) shows that phase noise in 1 MHz offset frequency from the carrier is -122 dBc/Hz and tuning range is 2 to 2.8 GHz. The power consumption of the core is 2.49 mW.
基金supported by the National Natural Science Foundation of China (No. 61871214)the Natural Science Foundation of Jiangsu Province(No. BK20180066)+2 种基金Fundamental Research Funds for the Central Universities (No. NS2018028)the Six Talent Peaks Project in Jiangsu Province (No. DZXX-005)the Postgraduate Research & Practice Innovation Program of Jiangsu Province (No. KYCX17_0289)。
文摘We propose a photonic-assisted single system for measuring the frequency and phase noise of microwave signals in a large spectral range. Both the frequency and phase noise to be measured are extracted from the phase difference between the signal under testing and its replica delayed by a span of fiber and a variable optical delay line(VODL). The system calibration, frequency measurement, and phase noise measurement are performed by adjusting the VODL at different working modes. Accurate frequency and phase noise measurement for microwave signals in a large frequency range from 5 to 50 GHz is experimentally demonstrated.
基金supported by the Humanity and Social Science Foundation of Chinese Ministry of Education (No.19YJC880053)the Natural Science Foundation of Zhejiang Province (No.LQ18F010008)+3 种基金the Philosophy and Social Science Planning Project of Zhejiang Province (No.19NDJC0103YB)the Natural Science Foundation of Ningbo (No.2018A610092)the Research Fund Project of Ningbo Institute of Finance&Economics (No.1320171002)the Education and Teaching Reform Program of Ningbo Institute of Finance&Economics (No.20jyyb16)。
文摘A low phase noise millimeter-wave(MMW) signal generator is proposed and experimentally demonstrated with a C-band passively Fabry-Pérot(F-P) quantum dot mode-locked laser. A novel method is proposed to generate low phase noise MMW signal, which is simply based on a commercial off-the-shelf dual-driven Li Nb O3 Mach-Zehnder modulator and a passively F-P quantum dot mode-locked laser. MMW signal with the frequency of 30 GHz, 45 GHz and 90 GHz respectively is obtained experimentally. Single-sideband phase noise of the 30 GHz and 45 GHz MMW signal is-112 d Bc/Hz and-106 d Bc/Hz at an offset of 1 k Hz, respectively. The linewidth of the 30 GHz and 45 GHz MMW signal is about from 225 Hz and 239 Hz. This is considered a very simple MMW generator with a quasi-tunable broadband and ultra-low phase noise.
文摘Intensity noise including Mode Partition Noise (MPN) and Mode Hopping Noise (MHN), and Phase/Frequency Noise Spectrum (FNS) are calculated for a two-mode semiconductor laser. RIN is derived considering of MPN and MHN effect.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.12103059,12033007,12303077,and 12303076)the Fund from the Xi’an Science and Technology Bureau,China(Grant No.E019XK1S04)the Fund from the Youth Innovation Promotion Association of the Chinese Academy of Sciences(Grant No.1188000XGJ).
文摘We demonstrate coherent optical frequency dissemination over a distance of 972 km by cascading two spans where the phase noise is passively compensated for.Instead of employing a phase discriminator and a phase locking loop in the conventional active phase control scheme,the passive phase noise cancellation is realized by feeding double-trip beat-note frequency to the driver of the acoustic optical modulator at the local site.This passive scheme exhibits fine robustness and reliability,making it suitable for long-distance and noisy fiber links.An optical regeneration station is used in the link for signal amplification and cascaded transmission.The phase noise cancellation and transfer instability of the 972-km link is investigated,and transfer instability of 1.1×10^(-19)at 10^(4)s is achieved.This work provides a promising method for realizing optical frequency distribution over thousands of kilometers by using fiber links.
文摘We have demonstrated a distributed vibration sensor based on phase-sensitive optical time-domain reflectometer (φ-OTDR) system exhibiting immunity to the laser phase noise. Two laser sources with different linewidth and phase noise levels are used in the φ-OTDR system, respectively. Based on the phase noise power spectrum density of both lasers, the laser phase is almost unchanged during an extremely short period of time, hence, the impact of phase noise can be suppressed effectively through phase difference between the Rayleigh scattered light from two adjacent sections of the fiber which define the gauge length. Based on the phase difference method, the external vibration can be located accurately at 41.01 km by the(φ-OTDR system incorporating these two lasers. Meanwhile, the average signal-to-noise ratio (SNR) of the retrieved vibration signal by using Laser I is found to be -37.7 dB, which is comparable to that of -37.5 dB by using Laser II although the linewidth and the phase noise level of the two lasers are distinct. The obtained results indicate that the phase difference method can enhance the performance of(φ-OTDR system with laser phase-noise immunity for distributed vibration sensing, showing potential application in oil-gas pipeline monitoring, perimeter security, and other fields.
基金The authors acknowledge the support from the Deanship of Scientific Research,Najran University.Kingdom of Saudi Arabia,for funding this work under the research groups funding program grant code number(NU/RG/SERC/11/3).
文摘The fiber nonlinearity and phase noise(PN)are the focused impairments in the optical communication system,induced by high-capacity transmission and high laser input power.The channels include high-capacity transmissions that cannot be achieved at the end side without aliasing because of fiber nonlinearity and PN impairments.Thus,addressing of these distortions is the basic objective for the 5G mobile network.In this paper,the fiber nonlinearity and PN are investigated using the assembled methodology of millimeter-wave and radio over fiber(mmWave-RoF).The analytical model is designed in terms of outage probability for the proposed mmWave-RoF system.The performance of mmWave-RoF against fiber nonlinearity and PN is studied for input power,output power and length using peak to average power ratio(PAPR)and bit error rate(BER)measuring parameters.The simulation outcomes present that the impacts of fiber nonlinearity and PNcan be balanced for a huge capacity mmWave-RoF model applying input power carefully.
基金supported by the National Natural Science Foundation of China(Nos.11904105,11874153,and 11621404)National Key R&D Program of China(No.2018YFA0306301)China Postdoctoral Science Foundation(No.2020M681223)。
文摘Gain-parameter-dependent transfer functions and phase-noise performances in a mode-locked Yb-doped fiber laser are measured in this study.It is discovered that the corner frequency in the amplitude and phase domains is determined by the absorption coefficient of the gain fiber,when the total absorption and other cavity parameters are fixed.This shows that an oscillator using gain fiber with higher dopant concentration accumulates more phase noise.Furthermore,we present net cavity dispersion-dependent transfer functions to verify the effect of dispersion management on the frequency response.We derive a guideline for optimizing mode-locked fiber laser design to achieve low phase noise and timing jitter.
基金Supported by the National Natural Science Foundation of China(11574352)the Strategic Priority Research Program of the Chinese Academy of Sciences(XDB21030100)。
文摘In this paper,we describe an optical path stabilization method in order to keep the phase of the clock laser fixed during the interrogation.The phase noise along the optical path of the clock laser is extracted from the heterodyne beat signals.Then an acousto-optic modulator(AOM)driven by direct digital synthesizer(DDS)receives a feedback signal to cancel the phase noise.The experimental results show that our system can effectively suppress additional phase noise.The fractional frequency instability is dropped to 1.76×10^-17/τ at 1 s,which is improved by two orders of magnitude than before.In the case of Rabi excitation with a pulse duration T=50 ms,frequency shift is 7.9 mHz due to the feedback system relock process.For phase noise from different frequency,the system has a good suppression effect on low frequency phase noise.
基金Project supported by the National Natural Science Foundation of China (Nos. 60725415 and 60971066)the National High-Tech R & D Program (863) of China (Nos. 2009AA01Z258 and 2009AA 01Z260)
文摘A 19 mW highly integrated GPS receiver with a ΣΔ fractional-N synthesizer is presented in this paper.Fractional-N frequency synthesizer architecture was adopted in this work, to provide more degrees of freedom in the synthesizer design.A high linearity low noise amplifier(LNA) is integrated into the chip.The radio receiver chip was fabricated in a 0.18 μm complementary metal oxide semiconductor(CMOS) process and packaged in a 48-pin 2 mm×2 mm land grid array chip scale package.The chip consumes 19 mW(LNA1 excluded) and the LNA1 6.3 mW.Measured performances are:noise figure<2 dB, channel gain=108 dB(LNA1 included), image rejection>36 dB, and-108 dBc/Hz @ 1 MHz phase noise offset from the carrier.The carrier noise ratio(C/N) can reach 41 dB at an input power of-130 dBm.The chip operates over a temperature range of-40, 120 °C and ±5% tolerance over the CMOS technology process.
基金supported by Japanese Government(Monbukagakusho,MEXT)Scholarship in 2012.
文摘One of the major limitations of using Interferometric Synthetic Aperture Radar(InSAR)in time series analysis is the low-phase coherence associated with rough terrain and vegetated areas,which results in limited spatial coverage in such regions.Permanent scatterers technique was introduced to overcome this limitation using time-series analysis.However,identifying major scatterers within a pixel requires the single-looked pixels oversampling which can be a demanding process especially with large interferometric stacks and vast study areas.Therefore,using multilooked temporal coherent pixels was proposed to increase processing efficiency and coverage by utilizing distributed targets,but this technique may exclude pixels with reliable phase returns because of their temporal varying neighboring pixels.In this paper,we propose a technique to identify multilooked temporal stable pixels with reliable phase returns independent of their neighboring pixels.We conduct a simulation analysis to relate the spatial coherence of a pixel with its expected temporal correlation in the time series analysis module.We found that a liberal temporal correlation threshold of 0.53 in multilooked pixels stack is equivalent to a spatial coherence threshold of 0.2 when using number of looks of 9,which is considered acceptable in temporal coherent pixels,in terms of phase standard deviation.Applying these findings to study the 2011 Tohoku earthquake in the northeastern part of Japan resulted in increasing the number of usable pixels and spatial coverage index by nearly 50.4%and 36.8%,respectively,compared to the temporal coherent pixels.Furthermore,we propose an approach to integrate GPS observations with InSAR time series analysis,which resulted in deformation maps of the megathrust 2011 Tohoku earthquake with mean RMSE of 11.4 mm and a correlation of 98%in comparison to GPS observations.
基金Project supported by the National Natural Science Foundation of China(No.61376031)。
文摘A 0.20–2.43 GHz fractional-N frequency synthesizer is presented for multi-band wireless communication systems,in which the scheme adopts low phase noise voltage-controlled oscillators(VCOs)and a charge pump(CP)with reduced current mismatch.VCOs that determine the out-band phase noise of a phase-locked loop(PLL)based frequency synthesizer are optimized using an automatic amplitude control technique and a high-quality factor figure-8-shaped inductor.A CP with a mismatch suppression architecture is proposed to improve the current match of the CP and reduce the PLL phase errors.Theoretical analysis is presented to investigate the influence of the current mismatch on the output performance of PLLs.Fabricated in a TSMC 0.18-μm CMOS process,the prototype operates from 0.20 to 2.43 GHz.The PLL synthesizer achieves an in-band phase noise of-96.8 dBc/Hz and an out-band phase noise of-122.8 dBc/Hz at the 2.43-GHz carrier.The root-mean-square jitter is 1.2 ps under the worst case,and the measured reference spurs are less than-65.3 dBc.The current consumption is 15.2 mA and the die occupies 850μm×920μm.
文摘Wireless backhaul is considered to be the key part of the future wireless network with dense small cell traffic and high capacity demand.In this paper,we focus on the design of a high spectral efficiency line-of-sight(LoS)multiple-input multiple-output(MIMO)system for millimeter wave backhaul using dual-polarized frequency division duplex(FDD).High spectral efficiency is very challenging to achieve for the system due to various physical impairments such as phase noise(PHN),timing offset(TO)as well as the poor condition number of the LoS MIMO.In this paper,we propose a holistic solution containing TO compensation,PHN estimation,precoder/decorrelator optimization of the LoS MIMO for wireless backhaul,and the interleaving of each part.We show that the proposed solution has a robust performance with end-to-end spectral efficiency of 60 bit/s/Hz for 88 MIMO.