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A Synchronization Acquisition Algorithm Based on the Frequency Hopping Pulses Combining
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作者 She Honghan Cheng Yufan +4 位作者 Zhang Wenzihan Zhang Yaohui Zhao Yuheng Shen Haoran Mou Ying 《China Communications》 SCIE CSCD 2024年第4期74-87,共14页
As modern electromagnetic environments are more and more complex,the anti-interference performance of the synchronization acquisition is becoming vital in wireless communications.With the rapid development of the digi... As modern electromagnetic environments are more and more complex,the anti-interference performance of the synchronization acquisition is becoming vital in wireless communications.With the rapid development of the digital signal processing technologies,some synchronization acquisition algorithms for hybrid direct-sequence(DS)/frequency hopping(FH)spread spectrum communications have been proposed.However,these algorithms do not focus on the analysis and the design of the synchronization acquisition under typical interferences.In this paper,a synchronization acquisition algorithm based on the frequency hopping pulses combining(FHPC)is proposed.Specifically,the proposed algorithm is composed of two modules:an adaptive interference suppression(IS)module and an adaptive combining decision module.The adaptive IS module mitigates the effect of the interfered samples in the time-domain or the frequencydomain,and the adaptive combining decision module can utilize each frequency hopping pulse to construct an anti-interference decision metric and generate an adaptive acquisition decision threshold to complete the acquisition.Theory and simulation demonstrate that the proposed algorithm significantly enhances the antiinterference and anti-noise performances of the synchronization acquisition for hybrid DS/FH communications. 展开更多
关键词 adaptive anti-interference frequency hopping synchronization acquisition
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Precise time frequency synchronization technology for bistatic radar 被引量:5
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作者 Huang Yulin Yang Jianyu Wu Junjie Xiong Jintao 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2008年第5期929-933,共5页
A complete method of synchronization technology of bistatic radar using global position system (GPS) is presented. The pulse per second signal (1PPS) is elaborately modified to increase the time synchronization pr... A complete method of synchronization technology of bistatic radar using global position system (GPS) is presented. The pulse per second signal (1PPS) is elaborately modified to increase the time synchronization precision and keep loop locking. A very high time synchronization precision is achieved. Using the modified 1PPS to discipline the local OCXO, the reference frequency signal achieves both high long term stability (LTS) and short term stability (STS) properties. An algorithm, named phase abrupt change CFAR is presented to restrain the 1PPS phase abrupt change and keep loop locking. The experimental results indicate that this time and frequency synchronization method is effective and the time synchronization precision of the synchronization system can be improved from ±100 ns to ±25 ns. In addition, the phase noise is improved to 20 dB. 展开更多
关键词 bistatic radar GPS time synchronization frequency phase synchronization.
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Modeling of cascaded high isolation bidirectional amplification in long-distance fiber-optic time and frequency synchronization system 被引量:1
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作者 Kuan-Lin Mu Xing Chen +2 位作者 Zheng-Kang Wang Yao-Jun Qiao Song Yu 《Chinese Physics B》 SCIE EI CAS CSCD 2021年第7期294-302,共9页
We propose a physical model of estimating noise and asymmetry brought by high isolation Bi-directional erbiumdoped fiber amplifiers(Bi-EDFAs),no spontaneous lasing even with high gain,in longdistance fiber-optic time ... We propose a physical model of estimating noise and asymmetry brought by high isolation Bi-directional erbiumdoped fiber amplifiers(Bi-EDFAs),no spontaneous lasing even with high gain,in longdistance fiber-optic time and frequency(T/F)synchronization system.It is found that the Rayleigh scattering noise can be suppressed due to the high isolation design,but the amplified spontaneous emission(ASE)noise generated by the high isolation Bi-EDFA and the bidirectional asymmetry of the transmission link caused by the high isolation Bi-EDFA will deteriorate the stability of the system.The calculated results show that under the influence of ASE noise,the frequency instability of a 1200 km system composed of 15 high isolation Bi-EDFAs is 1.773×10^(-13)/1 s.And the instability caused by asymmetry is 2.6064×10^(-16)/30000–35000 s if the total asymmetric length of the bidirectional link length is 30 m.The intensity noises originating from the laser and detector,the transfer delay fluctuations caused by the variation in ambient temperature and the jitter in laser output wavelength are also studied.The experiment composed of three high isolation Bi-EDFAs is done to confirm the theoretical analysis.In summary,the paper shows that the short-term instability of the T/F synchronization system composed of high isolation Bi-EDFAs is limited by the accumulation of ASE noise of amplifiers and the laser frequency drift,while the long-term instability is limited by the periodic variation in ambient temperature and the asymmetry of the amplifiers.The research results are useful for pointing out the direction to improve the stability of the fiber-optic T/F synchronization system. 展开更多
关键词 time and frequency synchronization erbium-doped fiber amplifier INSTABILITY Allan deviation
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Joint transfer of time and frequency signals and multi-point synchronization via fiber network 被引量:1
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作者 程楠 陈炜 +4 位作者 刘琴 徐丹 杨飞 桂有珍 蔡海文 《Chinese Physics B》 SCIE EI CAS CSCD 2016年第1期608-615,共8页
A system of jointly transferring time signals with a rate of 1 pulse per second (PPS) and frequency signals of 10 MHz via a dense wavelength division multiplex-based (DWDM) fiber is demonstrated in this paper. The... A system of jointly transferring time signals with a rate of 1 pulse per second (PPS) and frequency signals of 10 MHz via a dense wavelength division multiplex-based (DWDM) fiber is demonstrated in this paper. The noises of the fiber links are suppressed and compensated for by a controlled fiber delay line. A method of calibrating and characterizing time is described. The 1PPS is synchronized by feed-forward calibrating the fiber delays precisely. The system is experimen- tally examined via a 110 km spooled fiber in laboratory. The frequency stabilities of the user end with compensation are 1.8x 10-14 at 1 s and 2.0x 10-17 at 104 s average time. The calculated uncertainty of time synchronization is 13.1 ps, whereas the direct measurement of the uncertainty is 12 ps. Next, the frequency and 1PPS are transferred via a metropoli- tan area optical fiber network from one central site to two remote sites with distances of 14 km and 110 km. The frequency stabilities of 14 km link reach 3.0x 10-14 averaged in 1 s and 1.4x 10-17 in 104 s respectively; and the stabilities of 110 km link are 8.3 x 10-14 and 1.7 x 10-17, respectively. The accuracies of synchronization are estimated to be 12.3 ps for the 14 km link and 13.1 ps for the 110 km link, respectively. 展开更多
关键词 joint time and frequency transfer optical compensation time synchronization
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Impacts of space-time-frequency synchronization errors onwide-band target echo characteristics of bistatic/multistatic radar 被引量:3
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作者 Minghai Pan Qinghua Han +2 位作者 Shufeng Gong Weijun Long Haitao Wei 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2016年第3期562-573,共12页
Bistatic/multistatic radar has great potential advantages over its monostatic counterpart. However, the separation of a transmitter and a receiver leads to difficulties in locating the target position accurately and g... Bistatic/multistatic radar has great potential advantages over its monostatic counterpart. However, the separation of a transmitter and a receiver leads to difficulties in locating the target position accurately and guaranteeing space-timefrequency synchronization of the transmitter and the receiver.The error model of space-time-frequency synchronization in a motion platform of bistatic/multistatic radar is studied. The relationship between the space synchronization error and the transmitter platform position, receiver platform position, moving state, and beam pointing error, is analyzed. The effect of space synchronization error on target echo power is studied. The target scattering characteristics are restructured by many separate scattering centers of the target in high frequency regions. Based on the scattering centers model of the radar target, this radar target echo model and the simulation method are discussed. The algorithm of bistatic/multistatic radar target echo accurately reflects the scattering characteristics of the radar target, pulse modulation speciality of radar transmitting signals, and spacetime-frequency synchronization error characteristics between the transmitter station and the receiver station. The simulation of bistatic radar is completed in computer, and the results of the simulation validate the feasibility of the method. 展开更多
关键词 bistatic/multistatic radar space-time-frequency synchronization motion platform synchronization error radar target echo model
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Bunch-length measurement at a bunch-by-bunch rate based on time–frequency-domain joint analysis techniques and its application
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作者 Hong-Shuang Wang Xing Yang +2 位作者 Yong-Bin Leng Yi-Mei Zhou Ji-Gang Wang 《Nuclear Science and Techniques》 SCIE EI CAS CSCD 2024年第4期165-175,共11页
This paper presents a new technique for measuring the bunch length of a high-energy electron beam at a bunch-by-bunch rate in storage rings.This technique uses the time–frequency-domain joint analysis of the bunch si... This paper presents a new technique for measuring the bunch length of a high-energy electron beam at a bunch-by-bunch rate in storage rings.This technique uses the time–frequency-domain joint analysis of the bunch signal to obtain bunch-by-bunch and turn-by-turn longitudinal parameters,such as bunch length and synchronous phase.The bunch signal is obtained using a button electrode with a bandwidth of several gigahertz.The data acquisition device was a high-speed digital oscilloscope with a sampling rate of more than 10 GS/s,and the single-shot sampling data buffer covered thousands of turns.The bunch-length and synchronous phase information were extracted via offline calculations using Python scripts.The calibration coefficient of the system was determined using a commercial streak camera.Moreover,this technique was tested on two different storage rings and successfully captured various longitudinal transient processes during the harmonic cavity debugging process at the Shanghai Synchrotron Radiation Facility(SSRF),and longitudinal instabilities were observed during the single-bunch accumulation process at Hefei Light Source(HLS).For Gaussian-distribution bunches,the uncertainty of the bunch phase obtained using this technique was better than 0.2 ps,and the bunch-length uncertainty was better than 1 ps.The dynamic range exceeded 10 ms.This technology is a powerful and versatile beam diagnostic tool that can be conveniently deployed in high-energy electron storage rings. 展开更多
关键词 Bunch-by-bunch diagnostic Bunch-length measurement synchronous phase measurement Joint timefrequency-domain analysis Longitudinal instability
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RL and AHP-Based Multi-Timescale Multi-Clock Source Time Synchronization for Distribution Power Internet of Things
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作者 Jiangang Lu Ruifeng Zhao +2 位作者 Zhiwen Yu Yue Dai Kaiwen Zeng 《Computers, Materials & Continua》 SCIE EI 2024年第3期4453-4469,共17页
Time synchronization(TS)is crucial for ensuring the secure and reliable functioning of the distribution power Internet of Things(IoT).Multi-clock source time synchronization(MTS)has significant advantages of high reli... Time synchronization(TS)is crucial for ensuring the secure and reliable functioning of the distribution power Internet of Things(IoT).Multi-clock source time synchronization(MTS)has significant advantages of high reliability and accuracy but still faces challenges such as optimization of the multi-clock source selection and the clock source weight calculation at different timescales,and the coupling of synchronization latency jitter and pulse phase difference.In this paper,the multi-timescale MTS model is conducted,and the reinforcement learning(RL)and analytic hierarchy process(AHP)-based multi-timescale MTS algorithm is designed to improve the weighted summation of synchronization latency jitter standard deviation and average pulse phase difference.Specifically,the multi-clock source selection is optimized based on Softmax in the large timescale,and the clock source weight calculation is optimized based on lower confidence bound-assisted AHP in the small timescale.Simulation shows that the proposed algorithm can effectively reduce time synchronization delay standard deviation and average pulse phase difference. 展开更多
关键词 Multi-clock source time synchronization(TS) power Internet of Things reinforcement learning analytic hierarchy process
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Intelligent recognition and information extraction of radar complex jamming based on time-frequency features
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作者 PENG Ruihui WU Xingrui +3 位作者 WANG Guohong SUN Dianxing YANG Zhong LI Hongwen 《Journal of Systems Engineering and Electronics》 SCIE CSCD 2024年第5期1148-1166,共19页
In modern war,radar countermeasure is becoming increasingly fierce,and the enemy jamming time and pattern are changing more randomly.It is challenging for the radar to efficiently identify jamming and obtain precise p... In modern war,radar countermeasure is becoming increasingly fierce,and the enemy jamming time and pattern are changing more randomly.It is challenging for the radar to efficiently identify jamming and obtain precise parameter information,particularly in low signal-to-noise ratio(SNR)situations.In this paper,an approach to intelligent recognition and complex jamming parameter estimate based on joint time-frequency distribution features is proposed to address this challenging issue.Firstly,a joint algorithm based on YOLOv5 convolutional neural networks(CNNs)is proposed,which is used to achieve the jamming signal classification and preliminary parameter estimation.Furthermore,an accurate jamming key parameters estimation algorithm is constructed by comprehensively utilizing chi-square statistical test,feature region search,position regression,spectrum interpolation,etc.,which realizes the accurate estimation of jamming carrier frequency,relative delay,Doppler frequency shift,and other parameters.Finally,the approach has improved performance for complex jamming recognition and parameter estimation under low SNR,and the recognition rate can reach 98%under−15 dB SNR,according to simulation and real data verification results. 展开更多
关键词 complex jamming recognition time frequency feature convolutional neural network(CNN) parameter estimation
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The time and frequency system of the Tianma 65 m radio telescope
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作者 Lingling Wang Qinghui Liu Yong Cai 《Astronomical Techniques and Instruments》 CSCD 2024年第5期260-266,共7页
A time and frequency system is a critical component of Very Long Baseline Interferometry(VLBI)stations,providing stable and reliable standards that directly impact data processing quality.At the Tianma 65 m radio tele... A time and frequency system is a critical component of Very Long Baseline Interferometry(VLBI)stations,providing stable and reliable standards that directly impact data processing quality.At the Tianma 65 m radio telescope(TMRT),this system has been meticulously designed to ensure long-term reliability and high performance.It incorporates high-performance hydrogen atomic clocks,high-precision time standards,automatic signal switching,and robust system software.This comprehensive approach has enabled the system to achieve long-term reliable operation,successfully supporting both major national engineering tasks and daily scientific observations.The effectiveness of the system is evidenced by its consistent delivery of the precision and stability required for radio astronomy.This article provides an in-depth exploration of the design and operation of the time and frequency system at the Tianma 65 m telescope,examining various aspects of its architecture,implementation,and performance.By sharing these insights,we aim to contribute knowledge that could benefit similar systems at other VLBI stations,greatly advancing radio astronomy infrastructure. 展开更多
关键词 time and frequency system Hydrogen atomic clock RELIABILITY
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Effects of Serum Concentration, Synchronization Time and Confluence on the Cell-Cycle Synchronization Efficiency of Goat Fibroblasts
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作者 Van Khanh Nguyen Huong Thu Thi Vu +4 位作者 Au Thi Hoang Yen Kim Thi Pham Giang Thi Thanh Nhan Hung Phu Lai Lan Doan Pham 《Open Journal of Animal Sciences》 2024年第3期194-203,共10页
This study aims to evaluate the effect of serum concentration, synchronization time, and confluence degree on the synchronisation efficiency of goat fibroblast cycle. The results indicated that there was no difference... This study aims to evaluate the effect of serum concentration, synchronization time, and confluence degree on the synchronisation efficiency of goat fibroblast cycle. The results indicated that there was no difference in the percentage of nucleated fibroblasts in the G0/G1 stage between serum concentrations of 0.3% and 0.4% (83.89% and 82.69%, respectively, P > 0.05) as well as between serum concentrations of 0.2% and 0.5% (76.95% and 75.46%, respectively, P > 0.05). The percentage of nucleated fibroblasts in the G0/G1 stage was highest at the concentration of 0.3% and lowest in the control group (83.89% vs. 62.67%, P 0.05). The beneficial effect of high confluence was confirmed by the large percentage of nucleated fibroblasts at the G0/G1 stage. The 60% confluency was significantly lower than the 80% and 100% confluency (73.44%, 86.63%, and 87.17%, respectively, P < 0.05). The results indicate that the goat fibroblast cycle synchronization is the most effective at the serum concentration of 0.3%, 72 hours of synchronization and 100% confluency. 展开更多
关键词 Goat Fibroblast Cycle synchronisation Serum Concentration synchronization time CONFLUENCE
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Joint timing synchronization and frequency offset acquisition algorithm for MIMO OFDM systems 被引量:3
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作者 Liu Qi Hu Bo 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2009年第3期470-478,共9页
For multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) systems, a joint timing synchronization and frequency offset acquisition algorithm based on fractional Fourier transform ... For multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) systems, a joint timing synchronization and frequency offset acquisition algorithm based on fractional Fourier transform (FRFT) is proposed. The linear frequency modulation signals superimposed on the data signals are used as the training signals. By performing FRFT on the received signals and searching the peak value of the FRFT results, the receiver can realize timing synchronization and frequency offset acquisition simultaneously. Compared with the existing methods, the proposed algorithm can provide better timing synchronization performance and larger frequency offset acquisition range even under multi-path channels with low signal to noise ratio. Theoretical analysis and simulation results prove this point. 展开更多
关键词 multiple-input multiple-output orthogonal frequency division multiplexing timing synchronization frequency offset acquisition fractional Fourier transform.
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Discrimination of Motor Imagery Patterns by Electroencephalogram Phase Synchronization Combined With Frequency Band Energy 被引量:4
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作者 Chuanwei Liu Yunfa Fu +3 位作者 Jun Yang Xin Xiong Huiwen Sun Zhengtao Yu 《IEEE/CAA Journal of Automatica Sinica》 SCIE EI CSCD 2017年第3期551-557,共7页
Central nerve signal evoked by thoughts can be directly used to control a robot or prosthetic devices without the involvement of the peripheral nerve and muscles.This is a new strategy of human-computer interaction.A ... Central nerve signal evoked by thoughts can be directly used to control a robot or prosthetic devices without the involvement of the peripheral nerve and muscles.This is a new strategy of human-computer interaction.A method of electroencephalogram(EEG) phase synchronization combined with band energy was proposed to construct a feature vector for pattern recognition of brain-computer interaction based on EEG induced by motor imagery in this paper,rhythm and beta rhythm were first extracted from EEG by band pass filter and then the frequency band energy was calculated by the sliding time window;the instantaneous phase values were obtained using Hilbert transform and then the phase synchronization feature was calculated by the phase locking value(PLV) and the best time interval for extracting the phase synchronization feature was searched by the distribution of the PLV value in the time domain.Finally,discrimination of motor imagery patterns was performed by the support vector machine(SVM).The results showed that the phase synchronization feature more effective in4s-7s and the correct classification rate was 91.4%.Compared with the results achieved by a single EEG feature related to motor imagery,the correct classification rate was improved by 3.5 and4.3 percentage points by combining phase synchronization with band energy.These indicate that the proposed method is effective and it is expected that the study provides a way to improve the performance of the online real-time brain-computer interaction control system based on EEG related to motor imagery. 展开更多
关键词 Brain-computer interaction(BCI) electroencephalogram(EEG) frequency band energy motor imagery phase synchronization
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Pseudo-noise preamble based joint frame and frequency synchronization algorithm in OFDM communication systems 被引量:4
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作者 Qingfeng Jing Ming Cheng +2 位作者 Yuping Lu Weizhi Zhong Hongwei Yao 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2014年第1期1-9,共9页
Frame and frequency synchronization are essential for orthogonal frequency division multiplexing (OFDM) systems. The frame offset owing to incorrect start point position of the fast Fourier transform (FFT) window,... Frame and frequency synchronization are essential for orthogonal frequency division multiplexing (OFDM) systems. The frame offset owing to incorrect start point position of the fast Fourier transform (FFT) window, and the carrier frequency offset (CFO) due to Doppler frequency shift or the frequency mismatch between the transmitter and receiver oscil ators, can bring severe inter-symbol interference (ISI) and inter-carrier interference (ICI) for the OFDM system. Relying on the relatively good correlation charac-teristic of the pseudo-noise (PN) sequence, a joint frame offset and normalized CFO estimation algorithm based on PN preamble in time domain is developed to realize the frame and frequency synchronization in the OFDM system. By comparison, the perfor-mances of the traditional algorithm and the improved algorithm are simulated under different conditions. The results indicate that the PN preamble based algorithm both in frame offset estimation and CFO estimation is more accurate, resource-saving and robust even under poor channel condition, such as low signal-to-noise ratio (SNR) and large normalized CFO. 展开更多
关键词 orthogonal frequency division multiplexing (OFDM) frame synchronization carrier frequency offset (CFO) estimation preamble pseudo-noise sequence.
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Effects of Reduced Frequency on Network Configuration and Synchronization Transition 被引量:2
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作者 朱留华 《Chinese Physics Letters》 SCIE CAS CSCD 2016年第5期14-17,共4页
Synchronization of networked phase oscillators depends essentially on the correlation between the topological structure of the graph and the dynamical property of the elements. We propose the concept of 'reduced freq... Synchronization of networked phase oscillators depends essentially on the correlation between the topological structure of the graph and the dynamical property of the elements. We propose the concept of 'reduced frequency', a measure which can quantify natural frequencies of each pair of oscillators. Then we introduce an evolving network whose linking rules are controlled by its own dynamical property. The simulation results indicate that when the linking probability positively correlates with the reduced frequency, the network undergoes a first-order phase transition. Meanwhile, we discuss the circumstance under which an explosive synchronization can be ignited. The numerical results show that the peculiar butterfly shape correlation between frequencies and degrees of the nodes contributes to an explosive synchronization transition. 展开更多
关键词 of WORK as IT Effects of Reduced frequency on Network Configuration and synchronization Transition IS that
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A SYNCHRONIZATION ALGORITHM FOR HF(HIGH FREQUENCY) BROADBAND OFDM SYSTEM 被引量:2
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作者 Yang Lei Zhang You'ai 《Journal of Electronics(China)》 2008年第2期258-261,共4页
In this letter,a kind of associated synchronization algorithm which is suitable for HF(High Frequency) broadband OFDM(Orthogonal Frequency Division Multiplexing) system is presented based on describing and constructin... In this letter,a kind of associated synchronization algorithm which is suitable for HF(High Frequency) broadband OFDM(Orthogonal Frequency Division Multiplexing) system is presented based on describing and constructing the GMW(Gorden,Mills and Welch) sequence. The algorithm is based on the Schmidl and Minn's symbol timing principle,the constructed GMW sequence is trans-mitted and disposed,and the synchronization is adjudicated using the correlation of GMW sequence. The simulation result indicates that this algorithm has high performance synchronization ability under the low SNR(Signal to Noise Ratio) at two different kinds of channel models. 展开更多
关键词 HF (High frequency BROADBAND OFDM (Orthogonal frequency Division Multiplexing) synchronization
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Different Frequency Synchronization Theory and Its Frequency Measurement Practice Teaching Innovation Based on Lissajous Figure Method 被引量:1
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作者 Xin Geng Songlin Li +2 位作者 Guangming Huang Baoqiang Du Jianhua Chen 《Journal of Beijing Institute of Technology》 EI CAS 2018年第2期198-205,共8页
According to the requirement of multi-parameter time and frequency measurement without frequency normalization,a different frequency synchronization theory is proposed based on Lissajous figure method and the variatio... According to the requirement of multi-parameter time and frequency measurement without frequency normalization,a different frequency synchronization theory is proposed based on Lissajous figure method and the variation lawof Lissajous figure which are used in practice teaching of frequency measurement. The theory can achieve high-precision transmission and comparison of time and frequency and precise locking and tracking of phase and frequency,improve the level of scientific research on time and frequency for postgraduate,and promote practice teaching innovation of time frequency measurement for undergraduate. Utilizing the ratio of horizontal and vertical inflection point of the Lissajous figure,the nominal frequency of the measured signal is precisely calculated.The frequency deviation between the measured frequency and its nominal frequency can be obtained by combining the turning cycle of the Lissajous figure. By observing the phase relationship between the frequency standard signal and the measured signal,the accurate measurement of the frequency is implemented. Experimental results showthat the direct measurement and comparison better than the 10-11 order of magnitude with common frequency source can be finished between any signal frequencies.The frequency measurement method based on the theory has the advantage of simple operation,quick measurement speed,small error,lownoise and high measurement precision. It plays an important role in time synchronization,communications,metrology,scientific research,educational technology practice and equipment and other fields. 展开更多
关键词 Lissajous figure different frequency synchronization frequency measurement
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Phase synchronization and synchronization frequency of two-coupled van der Pol oscillators with delayed coupling
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作者 Hossein Gholizade-Narm Asad Azemi Morteza Khademi 《Chinese Physics B》 SCIE EI CAS CSCD 2013年第7期79-83,共5页
In this paper, phase synchronization and the frequency of two synchronized van der Pol oscillators with delay coupling are studied. The dynamics of such a system are obtained using the describing function method, and ... In this paper, phase synchronization and the frequency of two synchronized van der Pol oscillators with delay coupling are studied. The dynamics of such a system are obtained using the describing function method, and the necessary conditions for phase synchronization are also achieved. Finding the vicinity of the synchronization frequency is the major advantage of the describing function method over other traditional methods. The equations obtained based on this method justify the phenomenon of the synchronization of coupled oscillators on a frequency either higher, between, or lower than the highest, in between, or lowest natural frequency of the aggregate oscillators. Several numerical examples simulate the different cases versus the various synchronization frequency delays. 展开更多
关键词 van der Pol oscillator delay coupling phase synchronization synchronization frequency
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A novel frequency synchronization scheme for OFDM systems
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作者 王雯芳 李兵兵 《Journal of Harbin Institute of Technology(New Series)》 EI CAS 2008年第5期653-656,共4页
A novel frequency synchronization scheme for orthogonal frequency division multiplexing (OFDM) systems is proposed, including a novel frequency offset estimation algorithm and a novel frequency offset compensation alg... A novel frequency synchronization scheme for orthogonal frequency division multiplexing (OFDM) systems is proposed, including a novel frequency offset estimation algorithm and a novel frequency offset compensation algorithm. The frequency offset estimation includes both the fractional frequency offset (FFO) estimation and the integral frequency offset (IFO) estimation. Firstly, the FFO was obtained by the conventional ML algorithm in time domain. After the FFO was compensated in time domain, the IFO was obtained by the proposed algorithm based on the energy of virtual carriers. This algorithm needs only simple calculations and has a large frequency offset estimation range. Furthermore, it is insensitive to symbol synchronization errors and channel changing. Finally, the IFO was compensated based on the carrier-positions offset, which can be completed through carrier-positions cyclic shifts in frequency domain. This proposed frequency synchronization scheme can decrease the system redundancy without any need of assistant data, and can be applied to the fast synchronization with the only need of one OFDM symbol. The analyses and simulations show the improved performance of the proposed frequency synchronization scheme. 展开更多
关键词 OFDM systems frequency synchronization virtual carriers ML
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Implementation of Synchronization Technology in Orthogonal Frequency Division Multiplex System Based on Field Programming Gate Array
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作者 YI Qing-ming XIE Sheng-li 《Semiconductor Photonics and Technology》 CAS 2008年第1期32-36,共5页
In this paper,analyzed is the symbol synchronization algorithm in orthogonal frequency division multiplex(OFDM)system,and accomplished are the hardware circuit design of coarse and elaborate synchronization algorithms... In this paper,analyzed is the symbol synchronization algorithm in orthogonal frequency division multiplex(OFDM)system,and accomplished are the hardware circuit design of coarse and elaborate synchronization algorithms.Based on the analysis of coarse and elaborate synchronization algorithms,multiplexed are,the module accumulator,division and output judgement,which can evidently save the hardware resource cost.The analysis of circuit sequence and wave form simulation of the design scheme shows that the proposed method efficiently reduce system resources and power consumption. 展开更多
关键词 orthogonal frequency division multiplex timing synchronization field programmable gate array
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Complexity Effective Frequency and Sidelink Synchronization Algorithm for LTE Device-to-Device Communication Systems
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作者 Yong-An Jung Min-Goo Kang Young-Hwan You 《Computers, Materials & Continua》 SCIE EI 2020年第1期443-458,共16页
Device-to-device(D2D)communication is considered as a major challenge in the long term evolution(LTE)network wherein devices directly communicate with each other.One of the key challenges in D2D sidelink is reliable a... Device-to-device(D2D)communication is considered as a major challenge in the long term evolution(LTE)network wherein devices directly communicate with each other.One of the key challenges in D2D sidelink is reliable and reduced-complexity synchronization.To address this issue,a computationally efficient sequential detection scheme for integer carrier frequency offset and sidelink identity is proposed in the LTE-D2D system.To perform the frequency offset detection without retrieving the sidelink identity,the conjugate relation between two primary sidelink synchronization sequences is exploited,which facilitates the detection tasks of frequency offset and sidelink identity to be decoupled.It is demonstrated from simulation results that the inherent property of the sidelink synchronization sequences is effectively used for joint detection of frequency offset and sidelink identity with significantly reduced complexity,compared to existing estimation schemes. 展开更多
关键词 Long term evolution device-to-device communication carrier frequency offset sidelink identity sidelink synchronization
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