An algorithm for carrier frequency offset estimation with narrowband interference in burstmode transmissions is proposed.The algorithm is data-aided and has a feedforward structure that can be easily implemented digit...An algorithm for carrier frequency offset estimation with narrowband interference in burstmode transmissions is proposed.The algorithm is data-aided and has a feedforward structure that can be easily implemented digitally.The principle of the algorithm is based on a properly designed training sequence and an interpolation technique.Simulation results indicate that the estimation range is about ±20% of the symbol rate.The performance is satisfactory for a signal-to-noise ratio(SNR)as low as -13 dB and the mean square error(MSE)is approximately irrelevant to signal-to-interference ratio(SIR)values over -20 dB.展开更多
In the fifth-generation new radio(5G-NR) high-speed railway(HSR) downlink,a deep learning(DL) based Doppler frequency offset(DFO) estimation scheme is proposed by using the back propagation neural network(BPNN).The pr...In the fifth-generation new radio(5G-NR) high-speed railway(HSR) downlink,a deep learning(DL) based Doppler frequency offset(DFO) estimation scheme is proposed by using the back propagation neural network(BPNN).The proposed method mainly includes pre-training,training,and estimation phases,where the pre-training and training belong to the off-line stage,and the estimation is the online stage.To reduce the performance loss caused by the random initialization,the pre-training method is employed to acquire a desirable initialization,which is used as the initial parameters of the training phase.Moreover,the initial DFO estimation is used as input along with the received pilots to further improve the estimation accuracy.Different from the training phase,the initial DFO estimation in pre-training phase is obtained by the data and pilot symbols.Simulation results show that the mean squared error(MSE) performance of the proposed method is better than those of the available algorithms,and it has acceptable computational complexity.展开更多
Orthogonal frequency division multiplexing (OFDM) is one of the key techniques for long term evolution (LTE) system. Frequency offset estimation of OFDM is an essential issue. Especially in the high-speed environm...Orthogonal frequency division multiplexing (OFDM) is one of the key techniques for long term evolution (LTE) system. Frequency offset estimation of OFDM is an essential issue. Especially in the high-speed environment, the frequency offset will become large. Based on the features of LTE uplink physical random access channel (PRACH), this paper proposes a new frequency offset algorithm by using peak power ratio to enlarge the range of frequency offset estimation. According to the relation between frequency offset and the power delay profile (PDP), the ratio of the peak power of the PDP at the main window to that at the negative window or positive window is utilized to estimate frequency offset. Simulation results show that the new proposed algorithm extends the estimation range of frequency offset from 1 000 Hz to 1 250 Hz. Meanwhile the accuracy of frequency offset estimation is almost not lost. Particularly in low signal noise ratio (SNR), the new algorithm has lower mean square error (MSE) compared with traditional phase differential algorithm.展开更多
This article proposes a new algorithm of joint channel and carrier frequency-offset OCCFO) estimation for multi-user multi-input and multi-output orthogonal frequency division multiplexing (MIMO-OFDM) systems. A le...This article proposes a new algorithm of joint channel and carrier frequency-offset OCCFO) estimation for multi-user multi-input and multi-output orthogonal frequency division multiplexing (MIMO-OFDM) systems. A least square (LS) channel estimation and a carrier frequency offset (CFO) correlation estimation are combined in this contribution. CFOs are generally estimated using training sequences in a special synchronization timeslot. In this contribution, CFO estimation is further improved by taking advantages of channel estimation based on pilot symbols in traffic timeslots. The CFOs can be first obtained from the primary channel estimation. And then, with the knowledge of the CFOs estimated, channel estimation can be enhanced greatly. Computer simulation results indicate that the proposed JCCFO scheme is of good performance. Besides, the computational complexity is low.展开更多
A particle filter is proposed to perform joint estimation of the carrier frequency offset (CFO) and the channel in multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) wireless com...A particle filter is proposed to perform joint estimation of the carrier frequency offset (CFO) and the channel in multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) wireless communication systems. It marginalizes out the channel parameters from the sampling space in sequential importance sampling (SIS), and propagates them with the Kalman filter. Then the importance weights of the CFO particles are evaluated according to the imaginary part of the error between measurement and estimation. The varieties of particles are maintained by sequential importance resampling (SIR). Simulation results demonstrate this algorithm can estimate the CFO and the channel parameters with high accuracy. At the same time, some robustness is kept when the channel model has small variations.展开更多
A data-aided technique for cartier frequency offset estimation with continuous phase modulation (CPM) in burst- mode transmission is presented. The proposed technique first exploits a special pilot sequence, or trai...A data-aided technique for cartier frequency offset estimation with continuous phase modulation (CPM) in burst- mode transmission is presented. The proposed technique first exploits a special pilot sequence, or training sequence, to form a sinusoidal waveform. Then, an improved dichotomous search frequency offset estimator is introduced to determine the frequency offset using the sinusoid. Theoretical analysis and simulation results indicate that our estimator is noteworthy in the following aspects. First, the estimator can operate independently of timing recovery. Second, it has relatively low outlier, i.e., the minimum signal-to-noise ratio (SNR) required to guarantee estimation accuracy. Finally, the most important property is that our estimator is complexity-reduced compared to the existing dichotomous search methods: it eliminates the need for fast Fourier transform (FFT) and modulation removal, and exhibits faster convergence rate without accuracy degradation.展开更多
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
The carrier frequency offset(CFO)and impulse noise always affect the performance of underwater acoustic communication_systems.The CFO and impulse noise could be estimated by using the null subcarriers to cancel the ...The carrier frequency offset(CFO)and impulse noise always affect the performance of underwater acoustic communication_systems.The CFO and impulse noise could be estimated by using the null subcarriers to cancel the effects of the two types of interference.The null subcarriers estimation methods include optimal separate estimation and joint estimation.The separate estimation firstly estimates the CFO value and then estimates the impulse noise value.However,the CFO and impulse noise always affect each other when either of them is estimated separately.The performance could be improved by using the joint estimation.The results of simulations and experiments have showed that these two optimization methods have good performance and the joint estimation has better performance than the separate estimation method.There is 3 dB performance gain at the BER value of 10^(-2)when using the joint estimation method.Thus these methods could improve the system robustness by using the CFO compensation and impulse noise suppression.展开更多
A new carrier frequency offset estimation scheme for Orthogonal Frequency-Division Multiplexing (OFDM) systems is proposed. The carrier frequency offset estimation includes acquisition and tracking. The acquisition ra...A new carrier frequency offset estimation scheme for Orthogonal Frequency-Division Multiplexing (OFDM) systems is proposed. The carrier frequency offset estimation includes acquisition and tracking. The acquisition range of the proposed algorithm is as large as one half of the overall signal bandwidth. Comparison of the proposed scheme with Schmidl's algorithm by computer simulation illustrates the superior performance of the proposed scheme with regard to estimation accuracy in both AWGN channel and multipath channels.展开更多
基金Supported by the National Natural Science Foundation of China(61301089)
文摘An algorithm for carrier frequency offset estimation with narrowband interference in burstmode transmissions is proposed.The algorithm is data-aided and has a feedforward structure that can be easily implemented digitally.The principle of the algorithm is based on a properly designed training sequence and an interpolation technique.Simulation results indicate that the estimation range is about ±20% of the symbol rate.The performance is satisfactory for a signal-to-noise ratio(SNR)as low as -13 dB and the mean square error(MSE)is approximately irrelevant to signal-to-interference ratio(SIR)values over -20 dB.
基金Supported by the National Science Foundation Program of Jiangsu Province(No.BK20191378)the National Science Research Project of Jiangsu Higher Education Institutions(No.18KJB510034)+1 种基金the 11th Batch of China Postdoctoral Science Fund Special Funding Project(No.2018T110530)the National Natural Science Foundation of China(No.61771255)。
文摘In the fifth-generation new radio(5G-NR) high-speed railway(HSR) downlink,a deep learning(DL) based Doppler frequency offset(DFO) estimation scheme is proposed by using the back propagation neural network(BPNN).The proposed method mainly includes pre-training,training,and estimation phases,where the pre-training and training belong to the off-line stage,and the estimation is the online stage.To reduce the performance loss caused by the random initialization,the pre-training method is employed to acquire a desirable initialization,which is used as the initial parameters of the training phase.Moreover,the initial DFO estimation is used as input along with the received pilots to further improve the estimation accuracy.Different from the training phase,the initial DFO estimation in pre-training phase is obtained by the data and pilot symbols.Simulation results show that the mean squared error(MSE) performance of the proposed method is better than those of the available algorithms,and it has acceptable computational complexity.
基金supported by the National Natural Science Foundation of China (60572117)the Scientific Research Foundation for the returned Overseas Chinese scholars, State Education Ministry.
文摘Orthogonal frequency division multiplexing (OFDM) is one of the key techniques for long term evolution (LTE) system. Frequency offset estimation of OFDM is an essential issue. Especially in the high-speed environment, the frequency offset will become large. Based on the features of LTE uplink physical random access channel (PRACH), this paper proposes a new frequency offset algorithm by using peak power ratio to enlarge the range of frequency offset estimation. According to the relation between frequency offset and the power delay profile (PDP), the ratio of the peak power of the PDP at the main window to that at the negative window or positive window is utilized to estimate frequency offset. Simulation results show that the new proposed algorithm extends the estimation range of frequency offset from 1 000 Hz to 1 250 Hz. Meanwhile the accuracy of frequency offset estimation is almost not lost. Particularly in low signal noise ratio (SNR), the new algorithm has lower mean square error (MSE) compared with traditional phase differential algorithm.
基金the National Natural Science Foundation(60496312)the Hi-Tech Research and Development Program of China(2006AA01Z260), Gpbs(2006AA01Z283)the Fund for Foreign Scholars in University Research and Teaching Programs(B07005).
文摘This article proposes a new algorithm of joint channel and carrier frequency-offset OCCFO) estimation for multi-user multi-input and multi-output orthogonal frequency division multiplexing (MIMO-OFDM) systems. A least square (LS) channel estimation and a carrier frequency offset (CFO) correlation estimation are combined in this contribution. CFOs are generally estimated using training sequences in a special synchronization timeslot. In this contribution, CFO estimation is further improved by taking advantages of channel estimation based on pilot symbols in traffic timeslots. The CFOs can be first obtained from the primary channel estimation. And then, with the knowledge of the CFOs estimated, channel estimation can be enhanced greatly. Computer simulation results indicate that the proposed JCCFO scheme is of good performance. Besides, the computational complexity is low.
基金Project supported by the National Natural Science Foundation of China (Grant No.60572157)the International Cooper-ation Foundation (Grant No.2008DFA11950)
文摘A particle filter is proposed to perform joint estimation of the carrier frequency offset (CFO) and the channel in multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) wireless communication systems. It marginalizes out the channel parameters from the sampling space in sequential importance sampling (SIS), and propagates them with the Kalman filter. Then the importance weights of the CFO particles are evaluated according to the imaginary part of the error between measurement and estimation. The varieties of particles are maintained by sequential importance resampling (SIR). Simulation results demonstrate this algorithm can estimate the CFO and the channel parameters with high accuracy. At the same time, some robustness is kept when the channel model has small variations.
基金supported by the National Natural Science Foundation of China(Grant No.61301179)the Doctorial Programs Foundation of the Ministry of Education,China(Grant No.20110203110011)the Programme of Introducing Talents of Discipline to Universities,China(Grant No.B08038)
文摘A data-aided technique for cartier frequency offset estimation with continuous phase modulation (CPM) in burst- mode transmission is presented. The proposed technique first exploits a special pilot sequence, or training sequence, to form a sinusoidal waveform. Then, an improved dichotomous search frequency offset estimator is introduced to determine the frequency offset using the sinusoid. Theoretical analysis and simulation results indicate that our estimator is noteworthy in the following aspects. First, the estimator can operate independently of timing recovery. Second, it has relatively low outlier, i.e., the minimum signal-to-noise ratio (SNR) required to guarantee estimation accuracy. Finally, the most important property is that our estimator is complexity-reduced compared to the existing dichotomous search methods: it eliminates the need for fast Fourier transform (FFT) and modulation removal, and exhibits faster convergence rate without accuracy degradation.
基金supported by the National Natural Science Foundation of China(6130110561102069)+2 种基金the China Postdoctoral Science Foundation Funded Project(2013M531351)the Nanjing University of Aeronautics and Astronautics Founding(NN2012022)the Open Fund of Graduate Innovated Base(Laboratory)for the Nanjing University of Aeronautics and Astronautics(KFJJ120219)
文摘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.
基金supported by the Reasearch Fund for the Visiting Scholar Program by the China Scholarship Council(2011631504)The U.S.Science Foundation(CNS-1205665)+1 种基金the Fundamental Research Funds for the Central Universities(201112G020,201212G012)the National Natural Science Foundation of China(41176032)
文摘The carrier frequency offset(CFO)and impulse noise always affect the performance of underwater acoustic communication_systems.The CFO and impulse noise could be estimated by using the null subcarriers to cancel the effects of the two types of interference.The null subcarriers estimation methods include optimal separate estimation and joint estimation.The separate estimation firstly estimates the CFO value and then estimates the impulse noise value.However,the CFO and impulse noise always affect each other when either of them is estimated separately.The performance could be improved by using the joint estimation.The results of simulations and experiments have showed that these two optimization methods have good performance and the joint estimation has better performance than the separate estimation method.There is 3 dB performance gain at the BER value of 10^(-2)when using the joint estimation method.Thus these methods could improve the system robustness by using the CFO compensation and impulse noise suppression.
文摘A new carrier frequency offset estimation scheme for Orthogonal Frequency-Division Multiplexing (OFDM) systems is proposed. The carrier frequency offset estimation includes acquisition and tracking. The acquisition range of the proposed algorithm is as large as one half of the overall signal bandwidth. Comparison of the proposed scheme with Schmidl's algorithm by computer simulation illustrates the superior performance of the proposed scheme with regard to estimation accuracy in both AWGN channel and multipath channels.