Since the satellite communication goes in the trend of high-frequency and fast speed, the coefficients updating and the precision of the traditional pre-distortion feedback methods need to be further improved. On this...Since the satellite communication goes in the trend of high-frequency and fast speed, the coefficients updating and the precision of the traditional pre-distortion feedback methods need to be further improved. On this basis, this paper proposes dual loop feedback pre-distortion, which uses two first-order Volterra filter models to reduce the computing complexity and a dynamic error adjustment model to construct a revised feedback to ensure a better pre-distortion performance. The computation complexity, iterative convergence speed and precision of the proposed method are theoretically analyzed. Simulation results show that this dual loop feedback pre-distortion can speed the updating of coefficients and ensure the linearity of the amplifier output.展开更多
This paper presents a low sampling rate digital pre-distortion technique based on an improved Chebyshev polynomial for the non-linear distortion problem of amplifiers in 5G broadband communication systems.An improved ...This paper presents a low sampling rate digital pre-distortion technique based on an improved Chebyshev polynomial for the non-linear distortion problem of amplifiers in 5G broadband communication systems.An improved Chebyshev polynomial is used to construct the behavioural model of the broadband amplifier,and an undersampling technique is used to sample the output signal of the amplifier,reduce the sampling rate,and extract the pre-distortion parameters from the sampled signal through an indirect learning structure to finally correct the non-linearity of the amplifier system.This technique is able to improve the linearity and efficiency of the power amplifier and provides better flexibility.Experimental results show that by constructing the behavioural model of the amplifier using memory polynomials(MP),generalised polynomials(GMP)and modified Chebyshev polynomials respectively,the adjacent channel power ratio of the obtained system can be improved by more than 13.87d B,17.6dB and 19.98dB respectively compared to the output signal of the amplifier without digital pre-distortion.The Chebyshev polynomial improves the neighbourhood channel power ratio by 6.11dB and 2.38dB compared to the memory polynomial and generalised polynomial respectively,while the normalised mean square error is effectively improved and enhanced.This shows that the improved Chebyshev pre-distortion can guarantee the performance of the system and improve the non-linearity better.展开更多
In this paper,a Radio Over Fiber (ROF) system with a Digital Pre-Distorter (DPD) for WCDMA signal transmission is investigated.A Look-Up Table (LUT) based DPD and a Memory Polynomial (MP) DPD are applied in the ROF li...In this paper,a Radio Over Fiber (ROF) system with a Digital Pre-Distorter (DPD) for WCDMA signal transmission is investigated.A Look-Up Table (LUT) based DPD and a Memory Polynomial (MP) DPD are applied in the ROF link so as to suppress the out-of-band spurious spectrum and improve the transmission performance.The experimental results show that the out-of-band emission due to existence of the third-order Inter-Modulation Distortion (IMD3) is obviously sup-pressed by these two DPD.An Adjacent Channel Power Ratio (ACPR) improvement of 8 dB is ob-tained for a single-carrier WCDMA signal transmission.These two DPD have equal ability in lin-earization of the ROF system for a three-carrier WCDMA signal transmission.There is no apparent memory effects exist in the ROF link.展开更多
随着射频功率放大器的发射功率不断提升,特别是Doherty功放的广泛应用,使得功放的非线性特性不断增强。为了满足高线性化的需求,数字预失真(digital pre-distortion,DPD)技术要求达到更优的非线性校正效果。提出一种基于线性插值基的数...随着射频功率放大器的发射功率不断提升,特别是Doherty功放的广泛应用,使得功放的非线性特性不断增强。为了满足高线性化的需求,数字预失真(digital pre-distortion,DPD)技术要求达到更优的非线性校正效果。提出一种基于线性插值基的数字预失真方法,所提方法将线性插值基引入到数字预失真的行为建模中,达到优化的非线性校正效果。同时所提方法通过与查找表的实现方式结合,非常利于系统应用。仿真实验中采用20MHz长期演进(long term evolution,LTE)信号进行实验,新方法较广义记忆多项式方法在临道泄露比指标上改善了近7dBc以上。展开更多
FMCW radars with high resolution necessities the generation of highly linear,low phase noise,and low spur chirp signals with large bandwidth and a short modulation period.This paper reviews recent research progress on...FMCW radars with high resolution necessities the generation of highly linear,low phase noise,and low spur chirp signals with large bandwidth and a short modulation period.This paper reviews recent research progress on silicon-based FMCW signal generators,identifies advances in architecture,fundamental design,performance analysis,and applications of the FMCW synthesizer.展开更多
In this paper, a novel technique for power amplifier (PA) linearization is presented. The Legendre wavelet neural networks (LWNN) is first utilized to model PA and inverse structure of the PA by applying practical tra...In this paper, a novel technique for power amplifier (PA) linearization is presented. The Legendre wavelet neural networks (LWNN) is first utilized to model PA and inverse structure of the PA by applying practical transmission signals and the gradient descent algorithm is applied to estimate the coefficients of the LWNN. Secondly, this technique is implemented to identify and optimize the coefficient parameters of the proposed pre-distorter (PD), i.e., the inversion model of the PA. The proposed method is most efficient and the pre-distorter shows stability and effectiveness because of the rich properties of the LWNN. A quite significant improvement in linearity is achieved based on the measured data of the PA characteristics and out power spectrum has been compared.展开更多
We apply a Peak Shrinking and Interpolating(PSI)scheme to improve the Peak-to-Average Power Ratio(PAPR)performance in Multiple Intermediate-Frequency-over-Fiber(M-IFoF)based mobile fronthaul.The key idea is to detect ...We apply a Peak Shrinking and Interpolating(PSI)scheme to improve the Peak-to-Average Power Ratio(PAPR)performance in Multiple Intermediate-Frequency-over-Fiber(M-IFoF)based mobile fronthaul.The key idea is to detect the high peaks of the signal and shrink them,and then the shrunk peak values are interpolated into the original signal to reduce the PAPR.We also compare the PSI technique with the previous Tone-Reservation(TR)technique and Phase Pre-Distortion(PPD)technique in terms of PAPR reduction effect and computational complexity.The simulation results indicate that the PSI scheme can reduce the PAPR by more than 4.3 dB at 0.1%CCDF,which outperforms the two previous schemes with lower computational complexity.Furthermore,we find that altering M-IFoF system parameters has little effect on the performance of the PSI technique.展开更多
In this paper, the synchronous concurrent dual-band RF signal is used to drive the RF Power Amplifier (PA). The nonlinear characterization of a concurrent dual-band RF PA is discussed while two band signals in the dua...In this paper, the synchronous concurrent dual-band RF signal is used to drive the RF Power Amplifier (PA). The nonlinear characterization of a concurrent dual-band RF PA is discussed while two band signals in the dual-band are modulated by CDMA2000 and WCDMA signals. When the two band signals in the dual-band of the PA are modulated with the same signals, it is found that the nonlinearity of the PA can be expressed by any of the two corresponding baseband data. On the other hand, when the two band signals in the dual-band of the PA are modulated with two different signals, the PA nonlinearity cannot be characterized by any of the two corresponding baseband data. In this case, its nonlinearity has to be denoted by a composite signals consisting of the two baseband signals. Consequently, the requirements for the speed of the A/D converter can be largely reduced. The experimental results with CDMA2000 and WCDMA signals demonstrate the speed of the A/D converter required is only 30 M Sample Per Second (SaPS), but it will be at least 70 M SaPS for the conventional method.展开更多
文摘Since the satellite communication goes in the trend of high-frequency and fast speed, the coefficients updating and the precision of the traditional pre-distortion feedback methods need to be further improved. On this basis, this paper proposes dual loop feedback pre-distortion, which uses two first-order Volterra filter models to reduce the computing complexity and a dynamic error adjustment model to construct a revised feedback to ensure a better pre-distortion performance. The computation complexity, iterative convergence speed and precision of the proposed method are theoretically analyzed. Simulation results show that this dual loop feedback pre-distortion can speed the updating of coefficients and ensure the linearity of the amplifier output.
文摘This paper presents a low sampling rate digital pre-distortion technique based on an improved Chebyshev polynomial for the non-linear distortion problem of amplifiers in 5G broadband communication systems.An improved Chebyshev polynomial is used to construct the behavioural model of the broadband amplifier,and an undersampling technique is used to sample the output signal of the amplifier,reduce the sampling rate,and extract the pre-distortion parameters from the sampled signal through an indirect learning structure to finally correct the non-linearity of the amplifier system.This technique is able to improve the linearity and efficiency of the power amplifier and provides better flexibility.Experimental results show that by constructing the behavioural model of the amplifier using memory polynomials(MP),generalised polynomials(GMP)and modified Chebyshev polynomials respectively,the adjacent channel power ratio of the obtained system can be improved by more than 13.87d B,17.6dB and 19.98dB respectively compared to the output signal of the amplifier without digital pre-distortion.The Chebyshev polynomial improves the neighbourhood channel power ratio by 6.11dB and 2.38dB compared to the memory polynomial and generalised polynomial respectively,while the normalised mean square error is effectively improved and enhanced.This shows that the improved Chebyshev pre-distortion can guarantee the performance of the system and improve the non-linearity better.
基金Supported by the National Natural Science Foundation of China (No. 60972064)
文摘In this paper,a Radio Over Fiber (ROF) system with a Digital Pre-Distorter (DPD) for WCDMA signal transmission is investigated.A Look-Up Table (LUT) based DPD and a Memory Polynomial (MP) DPD are applied in the ROF link so as to suppress the out-of-band spurious spectrum and improve the transmission performance.The experimental results show that the out-of-band emission due to existence of the third-order Inter-Modulation Distortion (IMD3) is obviously sup-pressed by these two DPD.An Adjacent Channel Power Ratio (ACPR) improvement of 8 dB is ob-tained for a single-carrier WCDMA signal transmission.These two DPD have equal ability in lin-earization of the ROF system for a three-carrier WCDMA signal transmission.There is no apparent memory effects exist in the ROF link.
文摘随着射频功率放大器的发射功率不断提升,特别是Doherty功放的广泛应用,使得功放的非线性特性不断增强。为了满足高线性化的需求,数字预失真(digital pre-distortion,DPD)技术要求达到更优的非线性校正效果。提出一种基于线性插值基的数字预失真方法,所提方法将线性插值基引入到数字预失真的行为建模中,达到优化的非线性校正效果。同时所提方法通过与查找表的实现方式结合,非常利于系统应用。仿真实验中采用20MHz长期演进(long term evolution,LTE)信号进行实验,新方法较广义记忆多项式方法在临道泄露比指标上改善了近7dBc以上。
基金supported by the National Key Research and Development Program of China(No.2019YFB2204700 and No.2020YFB1805004)the Beijing Municipal Science and Technology Project(No.Z191100007519005)+2 种基金Guangdong International Collaboration Program(No.2020A0505100013)Guangdong Basic and Applied Basic Research Foundation(No.2019A1515110431)the Beijing Innovation Center for Future Chips(ICFC),Tsinghua University.
文摘FMCW radars with high resolution necessities the generation of highly linear,low phase noise,and low spur chirp signals with large bandwidth and a short modulation period.This paper reviews recent research progress on silicon-based FMCW signal generators,identifies advances in architecture,fundamental design,performance analysis,and applications of the FMCW synthesizer.
文摘In this paper, a novel technique for power amplifier (PA) linearization is presented. The Legendre wavelet neural networks (LWNN) is first utilized to model PA and inverse structure of the PA by applying practical transmission signals and the gradient descent algorithm is applied to estimate the coefficients of the LWNN. Secondly, this technique is implemented to identify and optimize the coefficient parameters of the proposed pre-distorter (PD), i.e., the inversion model of the PA. The proposed method is most efficient and the pre-distorter shows stability and effectiveness because of the rich properties of the LWNN. A quite significant improvement in linearity is achieved based on the measured data of the PA characteristics and out power spectrum has been compared.
文摘We apply a Peak Shrinking and Interpolating(PSI)scheme to improve the Peak-to-Average Power Ratio(PAPR)performance in Multiple Intermediate-Frequency-over-Fiber(M-IFoF)based mobile fronthaul.The key idea is to detect the high peaks of the signal and shrink them,and then the shrunk peak values are interpolated into the original signal to reduce the PAPR.We also compare the PSI technique with the previous Tone-Reservation(TR)technique and Phase Pre-Distortion(PPD)technique in terms of PAPR reduction effect and computational complexity.The simulation results indicate that the PSI scheme can reduce the PAPR by more than 4.3 dB at 0.1%CCDF,which outperforms the two previous schemes with lower computational complexity.Furthermore,we find that altering M-IFoF system parameters has little effect on the performance of the PSI technique.
基金Supported by the National Science and Technology Major Project of China (2010ZX03007-003-04)the National Natural Science Foundation of China (No. 61171040)+4 种基金the Key Project of International Cooperation of the Provincial Science and Technology Major Projects of Zhejiang (2010C14007)the Provincial Natural Science Foundation of Zhejiang (Y1101270)the Natural Science Foundation of Ningbo (2011A610188)Key Project of International Scientific and Technical Cooperation of Yunnan (2009AC010)Excellent Papers Engagement Fund of Ningbo University (PY20100004)
文摘In this paper, the synchronous concurrent dual-band RF signal is used to drive the RF Power Amplifier (PA). The nonlinear characterization of a concurrent dual-band RF PA is discussed while two band signals in the dual-band are modulated by CDMA2000 and WCDMA signals. When the two band signals in the dual-band of the PA are modulated with the same signals, it is found that the nonlinearity of the PA can be expressed by any of the two corresponding baseband data. On the other hand, when the two band signals in the dual-band of the PA are modulated with two different signals, the PA nonlinearity cannot be characterized by any of the two corresponding baseband data. In this case, its nonlinearity has to be denoted by a composite signals consisting of the two baseband signals. Consequently, the requirements for the speed of the A/D converter can be largely reduced. The experimental results with CDMA2000 and WCDMA signals demonstrate the speed of the A/D converter required is only 30 M Sample Per Second (SaPS), but it will be at least 70 M SaPS for the conventional method.
