The in-band full-duplex(IBFD)mechanism is of interest in beyond 5 G systems due to its potential to enhance spectral efficiency and reduce delay.To achieve the maximum gain of IBFD systems,the significant self-interfe...The in-band full-duplex(IBFD)mechanism is of interest in beyond 5 G systems due to its potential to enhance spectral efficiency and reduce delay.To achieve the maximum gain of IBFD systems,the significant self-interference(SI)must be efficiently suppressed.The challenges of wideband selfinterference cancellation(SIC)lie in the radio frequency(RF)domain,where the performance will be limited by the hardware.This paper reviews current RF cancellation mechanisms and investigates an efficient mechanism for future wideband systems with minimum complexity.The working principle and implementation details of multi-tap cancellers are first introduced,then an optical domain-based RF canceller is reviewed,and a novel low-cost design is proposed.To minimize the cost and complexity of the canceller,the minimum required number of taps are analyzed.Simulation results show that with the commonly used 12-bits analog-to-digital converter(ADC)at the receiver,the novel optical domain-based canceller can enable efficient SIC in the 3 GPP LTE specifications compatible system within 400 MHz bandwidth.展开更多
The 3-D beamforming scheme has elite as evolving interest because of its efficiency to empower assorted techniques such as vertical and horizontal domains and emanation beamforming according to subscriber's provis...The 3-D beamforming scheme has elite as evolving interest because of its efficiency to empower assorted techniques such as vertical and horizontal domains and emanation beamforming according to subscriber's provisions. Usually, 3-D beamforming communication is set up on FDD/TDD approach those effects on the performance of spectrum and energy efficiency. Co-frequency and CoTime Full Duplex(CCFD) is an effective solution to improve the spectrum and energy efficiency by transmitting and receiving simultaneously in frequency and time domain. While, CCFD communication often face the self-interference issue when communication occurs, simultaneously. Consequently, in this paper a self-interference elimination by physical feedback channel in CCFD for 3-D Beamforming communication scheme is proposed to improve the over-all system performance in terms of energy and spectrum efficiency. The simulation and analytical outcomes demonstrated that the proposed system is superior than the traditional one.展开更多
Adaptive digital self-interference cancellation(ADSIC)is a significant method to suppress self-interference and improve the performance of the linear frequency modulated continuous wave(LFMCW)radar.Due to efficient im...Adaptive digital self-interference cancellation(ADSIC)is a significant method to suppress self-interference and improve the performance of the linear frequency modulated continuous wave(LFMCW)radar.Due to efficient implementation structure,the conventional method based on least mean square(LMS)is widely used,but its performance is not sufficient for LFMCW radar.To achieve a better self-interference cancellation(SIC)result and more optimal radar performance,we present an ADSIC method based on fractional order LMS(FOLMS),which utilizes the multi-path cancellation structure and adaptively updates the weight coefficients of the cancellation system.First,we derive the iterative expression of the weight coefficients by using the fractional order derivative and short-term memory principle.Then,to solve the problem that it is difficult to select the parameters of the proposed method due to the non-stationary characteristics of radar transmitted signals,we construct the performance evaluation model of LFMCW radar,and analyze the relationship between the mean square deviation and the parameters of FOLMS.Finally,the theoretical analysis and simulation results show that the proposed method has a better SIC performance than the conventional methods.展开更多
We discuss the physical layer security scheme in the Full-Duplex(FD)MIMO point-to-point two-way communication system with residual self-interference,in which legitimate nodes send confidential information and null spa...We discuss the physical layer security scheme in the Full-Duplex(FD)MIMO point-to-point two-way communication system with residual self-interference,in which legitimate nodes send confidential information and null space Artificial Noise(AN)while receiving information.Because the Channel State Information(CSI)of the eavesdropper is unavailable,we optimize the covariance matrices of the information signal as well as the allocation of the antenna for transmitting and receiving to minimize the signal power consumption under the target rate constraint.As a result,the power of AN is maximized within the limit of total power,so the interception capability of the eavesdropper is suppressed as much as possible.Since self-interference cannot be completely eliminated,the optimization process of one legitimate node depends on the optimization result of the other.By substituting self-interference power in the secrecy rate formula with its average value,the joint optimization process at the two nodes is transformed into two separate and solvable optimization processes.Then,the Water-Filling Algorithm(WFA)and bisection algorithm are used to get the optimal covariance matrices of the signal.Furthermore,we derive the theoretical lower bound of ergodic achievable secrecy rate under rayleigh channels to evaluate the performance of the scheme.The simulation results show that the theoretical derivation is correct,and the actual achievable rate is very close to the target rate,which means that the approximation in the optimization is feasible.The results also show that secrecy transmission can be realized because a considerable secrecy rate can be achieved.展开更多
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
Radio frequency(RF) self-interference is a key issue for the application of in-band full-duplex communication in beyond fifth generation and sixth generation communications.Compared with electronic technology, photoni...Radio frequency(RF) self-interference is a key issue for the application of in-band full-duplex communication in beyond fifth generation and sixth generation communications.Compared with electronic technology, photonic technology has the advantages of wide bandwidth and high tuning precision, exhibiting great potential to realize high interference cancellation depth over broad band.In this paper, a comprehensive overview of photonic enabled RF self-interference cancellation(SIC)is presented.The operation principle of photonic RF SIC is introduced, and the advances in implementing photonic RF SIC according to the realization mechanism of phase reversal are summarized.For further realistic applications, the multipath RF SIC and the integrated photonic RF SIC are also surveyed.Finally, the challenges and opportunities of photonic RF SIC technology are discussed.展开更多
We consider a cellular network with a full-duplex base station, multiple uplink users and an eavesdropper. The full-duplex base station transmits jamming signals to degrade the eavesdropper channel when receiving secu...We consider a cellular network with a full-duplex base station, multiple uplink users and an eavesdropper. The full-duplex base station transmits jamming signals to degrade the eavesdropper channel when receiving secure multi-user signals. To maximize the secrecy rate of uplink communications, we propose a distributed ascending-clock auction(ACA) algorithm to allocate subcarriers and jamming power. Specifically, the impact of the self-interference of the full-duplex base station on the secrecy rate is considered. The proposed algorithm consists of two parts. Firstly, subcarriers and the jamming power are respectively priced by the base station. Secondly, users select the subcarrier and the jamming power based on the price. Moreover, the convergence of the proposed auction algorithm is mathematically proved. Simulation results show that the proposed auction algorithm is more beneficial to improve the uplink secrecy performance compared to traditional auction algorithms.展开更多
In order to detect and cancel the self-interference(SI)signal from desired binary phase-shift keying(BPSK)signal,the polarization-based optimal detection(POD)scheme for cancellation of digital SI in a full-duplex(FD)s...In order to detect and cancel the self-interference(SI)signal from desired binary phase-shift keying(BPSK)signal,the polarization-based optimal detection(POD)scheme for cancellation of digital SI in a full-duplex(FD)system is proposed.The POD scheme exploits the polarization domain to isolate the desired signal from the SI signal and then cancel the SI to obtain the interference-free desired signal at the receiver.In FD communication,after antenna and analog cancellation,the receiver still contains residual SI due to non-linearities of hardware imperfections.In POD scheme,a likelihood ratio expression is obtained,which isolates and detects SI bits from the desired bits.After isolation of these signal points,the POD scheme cancels the residual SI.As compared to the conventional schemes,the proposed POD scheme gives significantly low bit error rate(BER),a clear constellation diagram to obtain the boundary between desired and SI signal points,and increases the receiver's SI cancellation performance in low signal to interference ratio(SIR)environment.展开更多
In this paper, we consider a full.duplex multiple.input multiple.output(MIMO) relaying network with the decode.and.forward(DF) protocol. Due to the full.duplex transmissions, the self.interference from the relay trans...In this paper, we consider a full.duplex multiple.input multiple.output(MIMO) relaying network with the decode.and.forward(DF) protocol. Due to the full.duplex transmissions, the self.interference from the relay transmitter to the relay receiver degrades the system performance. We thus propose an iterative beamforming structure(IBS) to mitigate the self.interference. In this method, the receive beamforming at the relay is optimized to maximize the signal.to.interference.plus.noise.ratio(Max.SINR), while the transmit beamforming at the relay is optimized to maximize the signal.to.leakage.plusnoise.ratio(Max.SLNR). To further improve the performance, the receive and transmit beamforming matrices are optimized between Max.SINR and Max.SLNR in an iterative manner. Furthermore, in the presence of the residual self.interference, a low.complexity whitening.filter(WF) maximum likelihood(ML) detector is proposed. In this detector, a WF is designed to transform a colored interference.plus.noise to a white noise, while the singular value decomposition is used to convert coupled spatial subchannels to parallelindependent ones. From simulations, we find that the proposed IBS performs much better than the existing schemes. Also, the proposed low.complexity detector significantly reduces the complexity of the conventional ML(CML) detector from exponential time(an exponential function of the number of the source transmit antennas) to polynomial one while achieving a slightly better BER performance than the CML due to interference whitening.展开更多
Recent research shows that it is possible to achieve the full-duplex system by cancelling strong self-interference signals, which can be divided into three classes respectively, i.e., passive cancellation, active canc...Recent research shows that it is possible to achieve the full-duplex system by cancelling strong self-interference signals, which can be divided into three classes respectively, i.e., passive cancellation, active cancellation and digital cancellation. This pa- per tries to achieve the full-duplex system without using active cancellation, thus a full-duplex system using a joint mechanism based on a novel passive cancellation method and a novel digital cancellation method is proposed. Therein, a good antenna place- ment guided by the theory of the antenna electromagnetic field for the passive cancellation is presented. For the proposed digital can- cellation method, unlike previous separate mechanisms, it is de- signed by using the recursive least square (RLS) algorithm jointly with passive cancellation. The self-interference channel state in- formation (CSI) is transferred as the input of digital cancellation to balance the performance and the complexity. Experimental results show that the proposed self-interference cancellation mechanism can achieve about 85 dB which is better than the previous re- search. Meanwhile, this design provides a better performance compared with half-duplex with both line-of-sight channel and non- line-of-sight channel.展开更多
We study the optimal precoding for a full-duplex (FD) system, where one FD multi-antenna base station (BS) respectively transmits to and receives from two half-duplex single-antenna mobile users (MUs) on the same time...We study the optimal precoding for a full-duplex (FD) system, where one FD multi-antenna base station (BS) respectively transmits to and receives from two half-duplex single-antenna mobile users (MUs) on the same time slot and frequency band. At the FD BS, the received signal from the desired MU is severely affected by the extremely strong self-interference (SI) from its transmit antennas to the receive antennas. In the presence of residual SI after imperfect SI cancellation, the downlink transmission rate maximization problem subject to a targeted uplink rate is formulated as a non-convex optimization problem to characterize the achievable rate region for the considered system. Considering the case in which the SI channel is strongly correlated, the above problem is transformed into a convex problem by exploiting the rank-one property of the SI channel, which can be solved efficiently. Finally, numerical results validate the effectiveness of the proposed scheme.展开更多
In the satellite-to-ground high-speed data transmission link,there are signal self-interference problems of symbols in the co-channel,as well as between orthogonal and polarized channels.A multichannel adaptive filter...In the satellite-to-ground high-speed data transmission link,there are signal self-interference problems of symbols in the co-channel,as well as between orthogonal and polarized channels.A multichannel adaptive filter is designed by constructing a multichannel Wiener-Hopf equation,and the influence of five channel nonideal factors is suppressed to improve the BER performance.Experiments show that this method is effective to suppress the signal selfinterference,and the BER floor is optimized from 1E3 to 1E-7.展开更多
This paper presents a design scheme of wire-line telephone system using self-interference(SI)cancellation technology in co-frequency co-time full-duplex(CCFD)system to realize absolute secure communication at the phys...This paper presents a design scheme of wire-line telephone system using self-interference(SI)cancellation technology in co-frequency co-time full-duplex(CCFD)system to realize absolute secure communication at the physical layer.This scheme can hide the target signal by skillfully releasing the high-power artificial noise to the whole link at the receiving node,and then make use of the receiver’s knowledge of the SI signal to achieve high dB SI cancellation with the help of analog domain SI cancellation technology in CCFD domain,so that the signal-to-noise ratio(SNR)received by the eavesdropper at any position of the link is far lower than that of the legitimate receiver,so as to realize the absolutely secure communication in the sense of Wyner principle.This paper not only puts forward the specific design scheme of absolutely secure communication telephone,but also analyzes the calculation of security capacity under different eavesdropping positions,different SI cancellation capability and different system parameters according to Shannon theory.展开更多
By employing a radio frequency(RF) feedback chain, the self-interference can be canceled efficiently in co-time co-frequency full duplex(CCFD). However, the evitable signal crosstalk which is caused by the imperfect R...By employing a radio frequency(RF) feedback chain, the self-interference can be canceled efficiently in co-time co-frequency full duplex(CCFD). However, the evitable signal crosstalk which is caused by the imperfect RF feedback chain isolation usually damages the self-interference cancelation(SIC) performance. To deal with this problem, firstly, we analyze the impact of RF feedback chain isolation on SIC performance. Then a digital preprocessing scheme with RF feedback chain is proposed in the multiple-antenna CCFD architecture. Using both analytical and experimental methods, we find that the proposed scheme achieves a better performance on SIC.展开更多
The phase modulation characteristics of a reflective liquid crystal (LC) spatial light modulator (SLM) under oblique incidence are studied by using our proposed self-interference method. The experimental setup of ...The phase modulation characteristics of a reflective liquid crystal (LC) spatial light modulator (SLM) under oblique incidence are studied by using our proposed self-interference method. The experimental setup of the method is very simple and has good robustness to mechanical vibrations. By changing the gray value of the combined grayscale loaded on the LC-SLM, different sheared fringe patterns, generated by the interference between the constant phase-modulated beam and the +1-order diffracted beam of the blazed grating, can be obtained. The amount of phase modulation of the LC-SLM is obtained by subtracting the phase of the two side lobes in the frequency domain. By turning the turntable where the SLM is mounted, the phase modulation characteristics at different incident angles can be measured. The experimental results show that the phase modulation curves do not change significantly with the small angle. When the angle is large (i.e. larger than 10°), the phase modulation curves become different, especially for the high gray levels. With the increase of the incident angle, the phase modulation depth is reduced. The results indicate that the incident angle plays an important role in the performance of the phase modulation of an LC-SLM.展开更多
Real-time single-shot measurement of the femtosecond electron beam duration in laser wakefield accelerators is discussed for both experimental design and theoretical analysis that combines polarimetry and interferomet...Real-time single-shot measurement of the femtosecond electron beam duration in laser wakefield accelerators is discussed for both experimental design and theoretical analysis that combines polarimetry and interferometry.The probe pulse polarization is rotated by the azimuthal magnetic field of the electron beam and then introduced into a Michelson-type interferometer for self-interference. The electron beam duration is obtained from the region size of the interference fringes, which is independent of the pulse width of the probe laser. Using a larger magnification system or incident angle, the measurement resolution can be less than 1 fs.展开更多
CRISPR-Cas systems provide bacteria and archaea with adaptive immunity against mobile genetic elements(MGEs)through uptake of invader-derived spacers.De novo adaptation samples spacers from both invaders and hosts,whe...CRISPR-Cas systems provide bacteria and archaea with adaptive immunity against mobile genetic elements(MGEs)through uptake of invader-derived spacers.De novo adaptation samples spacers from both invaders and hosts,whereas primed adaptation shows higher specificity to sample spacers from invaders in many model systems as well as in the subtype I-F system of Zymomonas mobilis.Self-derived spacers will lead to CRISPR self-interference.However,our in vivo study demonstrated that this species used the microhomology-mediated end joining(MMEJ)pathway to efficiently repair subtype I-F CRISPR-Cas system-mediated DNA breaks guided by the self-targeting spacers.MMEJ repair of DNA breaks requires direct microhomologous sequences flanking the protospacers and leads to DNA deletions covering the protospacers.Importantly,CRISPR-mediated genomic DNA breaks failed to be repaired via MMEJ pathway in presence of higher copies of short homologous DNA.Moreover,CRISPR-cleaved exogenous plasmid DNA was failed to be repaired through MMEJ pathway,probably due to the inhibition of MMEJ by the presence of higher copies of the plasmid DNA in Z.mobilis.Our results infer that MMEJ pathway discriminates DNA damages between in the host chromosome versus mobile genetic element(MGE)DNA,and maintains genome stability post CRISPR immunity in Z.mobilis.展开更多
基金supported by the research grant from Huawei Technologies(Sweden)ABsupported by the U.K.Engineering and Physical Sciences Research Council(EPSRC)under Grant EP/P009549/1。
文摘The in-band full-duplex(IBFD)mechanism is of interest in beyond 5 G systems due to its potential to enhance spectral efficiency and reduce delay.To achieve the maximum gain of IBFD systems,the significant self-interference(SI)must be efficiently suppressed.The challenges of wideband selfinterference cancellation(SIC)lie in the radio frequency(RF)domain,where the performance will be limited by the hardware.This paper reviews current RF cancellation mechanisms and investigates an efficient mechanism for future wideband systems with minimum complexity.The working principle and implementation details of multi-tap cancellers are first introduced,then an optical domain-based RF canceller is reviewed,and a novel low-cost design is proposed.To minimize the cost and complexity of the canceller,the minimum required number of taps are analyzed.Simulation results show that with the commonly used 12-bits analog-to-digital converter(ADC)at the receiver,the novel optical domain-based canceller can enable efficient SIC in the 3 GPP LTE specifications compatible system within 400 MHz bandwidth.
基金supported by National Natural Science Foundation of China (Nos.61172107,61172110)National High Technical Research and Development Program (863 Program) of China (No.2015AA016306)+1 种基金Major Projects in Liaoning Province Science and Technology Innovation (No.201302001)Fundamental Research Funds for the Central Universities of China (No.DUT13LAB06)
文摘The 3-D beamforming scheme has elite as evolving interest because of its efficiency to empower assorted techniques such as vertical and horizontal domains and emanation beamforming according to subscriber's provisions. Usually, 3-D beamforming communication is set up on FDD/TDD approach those effects on the performance of spectrum and energy efficiency. Co-frequency and CoTime Full Duplex(CCFD) is an effective solution to improve the spectrum and energy efficiency by transmitting and receiving simultaneously in frequency and time domain. While, CCFD communication often face the self-interference issue when communication occurs, simultaneously. Consequently, in this paper a self-interference elimination by physical feedback channel in CCFD for 3-D Beamforming communication scheme is proposed to improve the over-all system performance in terms of energy and spectrum efficiency. The simulation and analytical outcomes demonstrated that the proposed system is superior than the traditional one.
文摘Adaptive digital self-interference cancellation(ADSIC)is a significant method to suppress self-interference and improve the performance of the linear frequency modulated continuous wave(LFMCW)radar.Due to efficient implementation structure,the conventional method based on least mean square(LMS)is widely used,but its performance is not sufficient for LFMCW radar.To achieve a better self-interference cancellation(SIC)result and more optimal radar performance,we present an ADSIC method based on fractional order LMS(FOLMS),which utilizes the multi-path cancellation structure and adaptively updates the weight coefficients of the cancellation system.First,we derive the iterative expression of the weight coefficients by using the fractional order derivative and short-term memory principle.Then,to solve the problem that it is difficult to select the parameters of the proposed method due to the non-stationary characteristics of radar transmitted signals,we construct the performance evaluation model of LFMCW radar,and analyze the relationship between the mean square deviation and the parameters of FOLMS.Finally,the theoretical analysis and simulation results show that the proposed method has a better SIC performance than the conventional methods.
基金This work was supported by the National Nature Science Foundation of China(No.61971080,No.61471076)Chongqing Research Program of Basic Research and Frontier Exploration(No.cstc2018jcyjAX0432)the Key Project of Science and Technology Research of Chongqing Education Commission(No.KJZD-K201800603,No.KJZD-M201900602).
文摘We discuss the physical layer security scheme in the Full-Duplex(FD)MIMO point-to-point two-way communication system with residual self-interference,in which legitimate nodes send confidential information and null space Artificial Noise(AN)while receiving information.Because the Channel State Information(CSI)of the eavesdropper is unavailable,we optimize the covariance matrices of the information signal as well as the allocation of the antenna for transmitting and receiving to minimize the signal power consumption under the target rate constraint.As a result,the power of AN is maximized within the limit of total power,so the interception capability of the eavesdropper is suppressed as much as possible.Since self-interference cannot be completely eliminated,the optimization process of one legitimate node depends on the optimization result of the other.By substituting self-interference power in the secrecy rate formula with its average value,the joint optimization process at the two nodes is transformed into two separate and solvable optimization processes.Then,the Water-Filling Algorithm(WFA)and bisection algorithm are used to get the optimal covariance matrices of the signal.Furthermore,we derive the theoretical lower bound of ergodic achievable secrecy rate under rayleigh channels to evaluate the performance of the scheme.The simulation results show that the theoretical derivation is correct,and the actual achievable rate is very close to the target rate,which means that the approximation in the optimization is feasible.The results also show that secrecy transmission can be realized because a considerable secrecy rate can be achieved.
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.
基金supported in part by the National Key R&D Program of China (No.2019YFB2203202)National Natural Science Foundation of China (Nos.62075026 and 61875028)+3 种基金National Research Foundation of China (No.61404130403)Program for Innovative Talents in Universities of Liaoning Province (No.LR2019017)Dalian Science and Technology Innovation Foundation (No.2018J11CY006)Fundamental Research Funds for the Central Universities(Nos.DUT18ZD106, DUT18GF102, and DUT18LAB20)。
文摘Radio frequency(RF) self-interference is a key issue for the application of in-band full-duplex communication in beyond fifth generation and sixth generation communications.Compared with electronic technology, photonic technology has the advantages of wide bandwidth and high tuning precision, exhibiting great potential to realize high interference cancellation depth over broad band.In this paper, a comprehensive overview of photonic enabled RF self-interference cancellation(SIC)is presented.The operation principle of photonic RF SIC is introduced, and the advances in implementing photonic RF SIC according to the realization mechanism of phase reversal are summarized.For further realistic applications, the multipath RF SIC and the integrated photonic RF SIC are also surveyed.Finally, the challenges and opportunities of photonic RF SIC technology are discussed.
基金supported in part by National High Technology Research and Development Program of China(863 Program)under Grant No.SS2015AA011306National High Technology Research and Development Program of China(863 Program)under Grant No.2014AA01A701National Natural Science Foundation of China under Grants No.61379006 and 61521003
文摘We consider a cellular network with a full-duplex base station, multiple uplink users and an eavesdropper. The full-duplex base station transmits jamming signals to degrade the eavesdropper channel when receiving secure multi-user signals. To maximize the secrecy rate of uplink communications, we propose a distributed ascending-clock auction(ACA) algorithm to allocate subcarriers and jamming power. Specifically, the impact of the self-interference of the full-duplex base station on the secrecy rate is considered. The proposed algorithm consists of two parts. Firstly, subcarriers and the jamming power are respectively priced by the base station. Secondly, users select the subcarrier and the jamming power based on the price. Moreover, the convergence of the proposed auction algorithm is mathematically proved. Simulation results show that the proposed auction algorithm is more beneficial to improve the uplink secrecy performance compared to traditional auction algorithms.
基金This work was supported by the Fundamental Research Funds for the Central Universities(2019XD-A07)the National Natural Science Foundation of China(61771063)the Huawei Innovation Research Program(HIRP)(2018040300246).
文摘In order to detect and cancel the self-interference(SI)signal from desired binary phase-shift keying(BPSK)signal,the polarization-based optimal detection(POD)scheme for cancellation of digital SI in a full-duplex(FD)system is proposed.The POD scheme exploits the polarization domain to isolate the desired signal from the SI signal and then cancel the SI to obtain the interference-free desired signal at the receiver.In FD communication,after antenna and analog cancellation,the receiver still contains residual SI due to non-linearities of hardware imperfections.In POD scheme,a likelihood ratio expression is obtained,which isolates and detects SI bits from the desired bits.After isolation of these signal points,the POD scheme cancels the residual SI.As compared to the conventional schemes,the proposed POD scheme gives significantly low bit error rate(BER),a clear constellation diagram to obtain the boundary between desired and SI signal points,and increases the receiver's SI cancellation performance in low signal to interference ratio(SIR)environment.
基金supported in part by the National Natural Science Foundation of China (Nos. 61271230, 61472190, and 61501238)the Open Research Fund of National Key Laboratory of Electromagnetic Environment, China Research Institute of Radiowave Propagation (No. 201500013)+4 种基金the open research fund of National Mobile Communications Research Laboratory, Southeast University, China (No. 2013D02)the Research Fund for the Doctoral Program of Higher Education of China (No. 20113219120019)the Foundation of Cloud Computing and Big Data for Agriculture and Forestry (117-612014063)the China Postdoctoral Science Foundation (2016M591852)Postdoctoral research funding program of Jiangsu Province (1601257C)
文摘In this paper, we consider a full.duplex multiple.input multiple.output(MIMO) relaying network with the decode.and.forward(DF) protocol. Due to the full.duplex transmissions, the self.interference from the relay transmitter to the relay receiver degrades the system performance. We thus propose an iterative beamforming structure(IBS) to mitigate the self.interference. In this method, the receive beamforming at the relay is optimized to maximize the signal.to.interference.plus.noise.ratio(Max.SINR), while the transmit beamforming at the relay is optimized to maximize the signal.to.leakage.plusnoise.ratio(Max.SLNR). To further improve the performance, the receive and transmit beamforming matrices are optimized between Max.SINR and Max.SLNR in an iterative manner. Furthermore, in the presence of the residual self.interference, a low.complexity whitening.filter(WF) maximum likelihood(ML) detector is proposed. In this detector, a WF is designed to transform a colored interference.plus.noise to a white noise, while the singular value decomposition is used to convert coupled spatial subchannels to parallelindependent ones. From simulations, we find that the proposed IBS performs much better than the existing schemes. Also, the proposed low.complexity detector significantly reduces the complexity of the conventional ML(CML) detector from exponential time(an exponential function of the number of the source transmit antennas) to polynomial one while achieving a slightly better BER performance than the CML due to interference whitening.
基金supported by the National Natural Science Foundation of China(601720456103200661271282)
文摘Recent research shows that it is possible to achieve the full-duplex system by cancelling strong self-interference signals, which can be divided into three classes respectively, i.e., passive cancellation, active cancellation and digital cancellation. This pa- per tries to achieve the full-duplex system without using active cancellation, thus a full-duplex system using a joint mechanism based on a novel passive cancellation method and a novel digital cancellation method is proposed. Therein, a good antenna place- ment guided by the theory of the antenna electromagnetic field for the passive cancellation is presented. For the proposed digital can- cellation method, unlike previous separate mechanisms, it is de- signed by using the recursive least square (RLS) algorithm jointly with passive cancellation. The self-interference channel state in- formation (CSI) is transferred as the input of digital cancellation to balance the performance and the complexity. Experimental results show that the proposed self-interference cancellation mechanism can achieve about 85 dB which is better than the previous re- search. Meanwhile, this design provides a better performance compared with half-duplex with both line-of-sight channel and non- line-of-sight channel.
基金supported by the National Natural Science Foundation of China(Nos.61401030 and 61501093)
文摘We study the optimal precoding for a full-duplex (FD) system, where one FD multi-antenna base station (BS) respectively transmits to and receives from two half-duplex single-antenna mobile users (MUs) on the same time slot and frequency band. At the FD BS, the received signal from the desired MU is severely affected by the extremely strong self-interference (SI) from its transmit antennas to the receive antennas. In the presence of residual SI after imperfect SI cancellation, the downlink transmission rate maximization problem subject to a targeted uplink rate is formulated as a non-convex optimization problem to characterize the achievable rate region for the considered system. Considering the case in which the SI channel is strongly correlated, the above problem is transformed into a convex problem by exploiting the rank-one property of the SI channel, which can be solved efficiently. Finally, numerical results validate the effectiveness of the proposed scheme.
基金supported by the Natural Science Foundation for Outstanding Young Scholars of Heilongjiang Province under Grant YQ2020F001the National Key Research and Development Program of China under Grant 2021YFB2900500the Fundamental Research Funds for the Central Universities under Grant FRFCU 9803503821
文摘In the satellite-to-ground high-speed data transmission link,there are signal self-interference problems of symbols in the co-channel,as well as between orthogonal and polarized channels.A multichannel adaptive filter is designed by constructing a multichannel Wiener-Hopf equation,and the influence of five channel nonideal factors is suppressed to improve the BER performance.Experiments show that this method is effective to suppress the signal selfinterference,and the BER floor is optimized from 1E3 to 1E-7.
基金Supported by the Natural Science Foundation of Hubei Province(2019CFB593)the National Natural Science Foundation of China(61961016)+1 种基金Ph.D.Research Start-up Foundation of Hubei Minzu University(MY2018B08)Graduate Education Innovation Plan of Hubei Minzu University(DC2000000119)。
文摘This paper presents a design scheme of wire-line telephone system using self-interference(SI)cancellation technology in co-frequency co-time full-duplex(CCFD)system to realize absolute secure communication at the physical layer.This scheme can hide the target signal by skillfully releasing the high-power artificial noise to the whole link at the receiving node,and then make use of the receiver’s knowledge of the SI signal to achieve high dB SI cancellation with the help of analog domain SI cancellation technology in CCFD domain,so that the signal-to-noise ratio(SNR)received by the eavesdropper at any position of the link is far lower than that of the legitimate receiver,so as to realize the absolutely secure communication in the sense of Wyner principle.This paper not only puts forward the specific design scheme of absolutely secure communication telephone,but also analyzes the calculation of security capacity under different eavesdropping positions,different SI cancellation capability and different system parameters according to Shannon theory.
基金supported by the National Natural Science Foundation of China under Grants No.61601064,No.61471108,No.61601065,and No.41404102supported by the Sichuan Youth Science and Technology Foundation under Grant No.2016JQ0012
文摘By employing a radio frequency(RF) feedback chain, the self-interference can be canceled efficiently in co-time co-frequency full duplex(CCFD). However, the evitable signal crosstalk which is caused by the imperfect RF feedback chain isolation usually damages the self-interference cancelation(SIC) performance. To deal with this problem, firstly, we analyze the impact of RF feedback chain isolation on SIC performance. Then a digital preprocessing scheme with RF feedback chain is proposed in the multiple-antenna CCFD architecture. Using both analytical and experimental methods, we find that the proposed scheme achieves a better performance on SIC.
基金financially supported by the National Natural Science Foundation of China(No.51705404)the China Postdoctoral Science Foundation(No.2016M602806)the Fundamental Research Funds for the Central Universities(No.xjj2017093)
文摘The phase modulation characteristics of a reflective liquid crystal (LC) spatial light modulator (SLM) under oblique incidence are studied by using our proposed self-interference method. The experimental setup of the method is very simple and has good robustness to mechanical vibrations. By changing the gray value of the combined grayscale loaded on the LC-SLM, different sheared fringe patterns, generated by the interference between the constant phase-modulated beam and the +1-order diffracted beam of the blazed grating, can be obtained. The amount of phase modulation of the LC-SLM is obtained by subtracting the phase of the two side lobes in the frequency domain. By turning the turntable where the SLM is mounted, the phase modulation characteristics at different incident angles can be measured. The experimental results show that the phase modulation curves do not change significantly with the small angle. When the angle is large (i.e. larger than 10°), the phase modulation curves become different, especially for the high gray levels. With the increase of the incident angle, the phase modulation depth is reduced. The results indicate that the incident angle plays an important role in the performance of the phase modulation of an LC-SLM.
基金supported by the National Natural Science Foundation of China(Nos.11127901,11425418,11505263,and 61521093)the Strategic Priority Research Program(B)(No.XDB16)+2 种基金Shanghai Sailing Program(Nos.17YF1421100 and 18YF1426000)the Youth Innovation Promotion Association CASthe State Key Laboratory Program of the Chinese Ministry of Science and Technology
文摘Real-time single-shot measurement of the femtosecond electron beam duration in laser wakefield accelerators is discussed for both experimental design and theoretical analysis that combines polarimetry and interferometry.The probe pulse polarization is rotated by the azimuthal magnetic field of the electron beam and then introduced into a Michelson-type interferometer for self-interference. The electron beam duration is obtained from the region size of the interference fringes, which is independent of the pulse width of the probe laser. Using a larger magnification system or incident angle, the measurement resolution can be less than 1 fs.
基金supported by the National Natural Science Foundation of China(31671291 to N.P.,31570055 to M.H.,and 31900400 to T.L.)the Fundamental Research Funds for the Central Universities(2662019PY028 to N.P.)National Natural Science Foundation of China(31900400)。
文摘CRISPR-Cas systems provide bacteria and archaea with adaptive immunity against mobile genetic elements(MGEs)through uptake of invader-derived spacers.De novo adaptation samples spacers from both invaders and hosts,whereas primed adaptation shows higher specificity to sample spacers from invaders in many model systems as well as in the subtype I-F system of Zymomonas mobilis.Self-derived spacers will lead to CRISPR self-interference.However,our in vivo study demonstrated that this species used the microhomology-mediated end joining(MMEJ)pathway to efficiently repair subtype I-F CRISPR-Cas system-mediated DNA breaks guided by the self-targeting spacers.MMEJ repair of DNA breaks requires direct microhomologous sequences flanking the protospacers and leads to DNA deletions covering the protospacers.Importantly,CRISPR-mediated genomic DNA breaks failed to be repaired via MMEJ pathway in presence of higher copies of short homologous DNA.Moreover,CRISPR-cleaved exogenous plasmid DNA was failed to be repaired through MMEJ pathway,probably due to the inhibition of MMEJ by the presence of higher copies of the plasmid DNA in Z.mobilis.Our results infer that MMEJ pathway discriminates DNA damages between in the host chromosome versus mobile genetic element(MGE)DNA,and maintains genome stability post CRISPR immunity in Z.mobilis.