POSSIBLY no other schoolreunion has aroused moreattention or had such apalpable ethos of com-merce than that of the BeijingFilm Institute class of 1978.
In this paper,a novel wideband 8-element multiple-input and multiple-output(MIMO)antenna based on Booker’s relation is proposed for the fifth generation(5G)handset applications.The 8 antenna elements are arranged sym...In this paper,a novel wideband 8-element multiple-input and multiple-output(MIMO)antenna based on Booker’s relation is proposed for the fifth generation(5G)handset applications.The 8 antenna elements are arranged symmetrically along the two longer vertical side-edge frames of the handset.Each antenna element is composed of a monopole and a slot radiation structure,in which wideband characteristic covering 3140-5620MHz can be obtained.Note that the L-shaped monopole and the slot can be deemed as complementary counterparts approximatively.Furthermore,the Z-parameter of the proposed wideband antenna element is equivalent to the shunt impedance of monopole as well as slot radiator.Based on Booker’s relation,the wideband input impedance characteristic is therein achieved compared with conventional wideband technique such as multiresonance.Four L-shaped stubs as well as two slots etched on the ground plane are utilized to achieve acceptable isolation performance better than 13 dB,with total efficiency higher than 60%and envelope correlation coefficients(ECCs)lower than 0.1.The proposed antenna scheme can be a good candidate for 5G handset applications with the advantages of wideband,simple structure,high efficiency,and acceptable isolation performance.Also,the scheme might be a rewarding attempt to promote the Booker’s relation in the application of 5G terminal MIMO antenna designs.展开更多
In this article,a single-board integrated millimeter-wave(mm-Wave)asymmetric full-digital beamforming(AFDBF)array is developed for beyond-fifth-generation(B5G)and sixth-generation(6G)communications.The proposed integr...In this article,a single-board integrated millimeter-wave(mm-Wave)asymmetric full-digital beamforming(AFDBF)array is developed for beyond-fifth-generation(B5G)and sixth-generation(6G)communications.The proposed integrated array effectively addresses the challenge of arranging a large number of ports in a full-digital array by designing vertical connections in a three-dimensional space and successfully integrating full-digital transmitting(Tx)and receiving(Rx)arrays independently in a single board.Unlike the traditional symmetric array,the proposed asymmetric array is composed of an 8×8 Tx array arranged in a square shape and an 8+8 Rx array arranged in an L shape.The center-to-center distance between two adjacent elements is 0.54k0 for both the Tx and Rx arrays,where k0 is the free-space wavelength at 27 GHz.The proposed AFDBF array possesses a more compact structure and lower system hardware cost and power consumption compared with conventional brick-type full-digital arrays.In addition,the energy efficiency of the proposed AFDBF array outperforms that of a hybrid beamforming array.The measurement results indicate that the operating frequency band of the proposed array is 24.25–29.50 GHz.An eight-element linear array within the Tx array can achieve a scanning angle ranging from-47°to+47°in both the azimuth and the elevation planes,and the measured scanning range of each eight-element Rx array is–45°to+45°.The measured maximum effective isotropic radiated power(EIRP)of the eight-element Tx array is 43.2 dBm at 28.0 GHz(considering the saturation point).Furthermore,the measured error vector magnitude(EVM)is less than 3%when 64-quadrature amplitude modulation(QAM)waveforms are used.展开更多
This article presents an 8-element dual-polarized phased-array transceiver(TRX)front-end IC for millimeter-wave(mm-Wave)5G new radio(NR).Power enhancement technologies for power amplifiers(PA)in mm-Wave 5G phased-arra...This article presents an 8-element dual-polarized phased-array transceiver(TRX)front-end IC for millimeter-wave(mm-Wave)5G new radio(NR).Power enhancement technologies for power amplifiers(PA)in mm-Wave 5G phased-array TRX are discussed.A four-stage wideband high-power class-AB PA with distributed-active-transformer(DAT)power combining and multi-stage second-harmonic traps is proposed,ensuring the mitigated amplitude-to-phase(AM-PM)distortions across wide carrier frequencies without degrading transmitting(TX)power,gain and efficiency.TX and receiving(RX)switching is achieved by a matching network co-designed on-chip T/R switch.In each TRX element,6-bit 360°phase shifting and 6-bit 31.5-dB gain tuning are respectively achieved by the digital-controlled vector-modulated phase shifter(VMPS)and differential attenuator(ATT).Fabricated in 65-nm bulk complementary metal oxide semiconductor(CMOS),the proposed TRX demonstrates the measured peak TX/RX gains of 25.5/21.3 dB,covering the 24−29.5 GHz band.The measured peak TX OP1dB and power-added efficiency(PAE)are 20.8 dBm and 21.1%,respectively.The measured minimum RX NF is 4.1 dB.The TRX achieves an output power of 11.0−12.4 dBm and error vector magnitude(EVM)of 5%with 400-MHz 5G NR FR2 OFDM 64-QAM signals across 24−29.5 GHz,covering 3GPP 5G NR FR2 operating bands of n257,n258,and n261.展开更多
In this study,fog simulations were conducted using the Fifth-Generation NCAR/Penn State Mesoscale Model (MM5) in and around the Yodo River Basin,Japan.The purpose is to investigate the MM5 performance of fog simulatio...In this study,fog simulations were conducted using the Fifth-Generation NCAR/Penn State Mesoscale Model (MM5) in and around the Yodo River Basin,Japan.The purpose is to investigate the MM5 performance of fog simulation for long-term periods.The simulations were performed for January,February,March,and July,2005 with a coarse 3-kin and a nested fine 1-km grid domains. Results of the simulations were compared with data from ten meteorological observatories,fog sampling site in Mt.Rokko,and visibility measurem...展开更多
NaGlobal vigation Satellite System(GNSS)positioning technology is widely used for its high precision,global,and all-weather service.However,in complex environments such as urban canyons,GNSS performance is often degra...NaGlobal vigation Satellite System(GNSS)positioning technology is widely used for its high precision,global,and all-weather service.However,in complex environments such as urban canyons,GNSS performance is often degraded due to signal occlusion and even fails to achieve positioning due to the insufficient visible satellites.Because of the characteristics of large band-width,low latency,and high Base Station(BS)density,the fifth-Generation mobile communication(5G)technology has gradually become a trend for positioning in cities while offering traditional communication service.To supply the communication demands of the User Equipment(UE),only one BS is usually considered to establish a connection with the UE during the BS construction.However,the positioning accuracy with a single BS in urban canyons will be significantly reduced.To further improve the positioning accuracy in such extreme scenarios,this paper proposes a simplified 5G/GNSS fusion positioning system architecture using observations from only a 5G BS and a GNSS satellite.In this system,the GNSS receiver is mounted on the 5G BS,and the measurements provided by the receiver are used to form the differential code and complete the position estimation.The positioning mathematical models of the system based on the original code and differential code are derived.Then,the impacts of the measurements noise and the time synchronization error on the positioning accuracy are analyzed theoretically.Finally,the positioning performance is investigated by a set of simulation experiments.Numerical results show that under the existing 5G measurement noise and 2 m’s code measurement noise,the improvement of the differential code based fusion positioning compared with the 5G-only positioning is more than 32%,which is also about 6%higher than the original code based fusion positioning.Besides,this improvement is not affected by the time synchronization error between the BS and the GNSS satellite.展开更多
In response to the downlink synchronization requirements of the user equipment(UE)or third-party radio equipment in fifth-generation(5G)mobile communication systems,a synchronization algorithm of primary synchroni-zat...In response to the downlink synchronization requirements of the user equipment(UE)or third-party radio equipment in fifth-generation(5G)mobile communication systems,a synchronization algorithm of primary synchroni-zation signal(PSS)was designed and developed in the 5G system based on block cross-correlation.According to the new characteristics of the 5G synchronization channel and broadcast channel,starting from the traditional downlink synchronization algorithm of long-term evolution(LTE),the detection performance of the algorithm under a low signal-to-noise ratio(SNR)is improved by introducing an incoherent accumulation,and the new scheme of joint coarse frequency offset estimation is used to improve the frequency offset estimation performance.Finally,the performance of the proposed synchronization algorithm is verified by conducting a simulation on a 5G downlink simulation platform based on MATLAB software.Simulation results show that the improved downlink synchronization algorithm has stable performance in the tapped delay line-C(TDL-C)and additive white Gaussian noise(AWGN)channels with large frequency deviation and low SNR.展开更多
The analytical lower bound of Spectral Efficiency(SE)of downlink transmission of the Massive Multiple Input Multiple Output(Ma-MIMO)system is analyzed.In this paper,we derive some novel and approximate mathematical ex...The analytical lower bound of Spectral Efficiency(SE)of downlink transmission of the Massive Multiple Input Multiple Output(Ma-MIMO)system is analyzed.In this paper,we derive some novel and approximate mathematical expressions for the lower bound of the SE of a Ma-MIMO with linear precoding schemes,i.e.,Minimum Mean Square Error(MMSE)and Zero-Forcing(ZF).For simulation analysis of the SE,we consider three joint users and antenna scheduling algorithms,namely,the semi-orthogonal,random,and distance-based user scheduling algorithms,whereas the antennas are selected based on Maximum Signal to Noise Ratio(MSNR)with scheduled users.The channel between the user and the transmitter is assumed to have characteristics of Small Scale Fading(SSF)and Large Scale Fading(LSF)with the Rayleigh fading model.We investigate the effect of the variation of transmitting SNR,the number of base station antennas(M),and the radius(R)of the cell area on the SE.We simulate the downlink transmission of Ma-MIMO and compare the simulation and analytical results.It is observed that the trends of variation of both results are similar to the variation of identical factors,and the difference between the simulated and analytical lower bounds of the SE is approximately 1-1.5 bits.The analytical lower bound is smaller than the simulation result.展开更多
The application of information and communications technology(ICT)in the education industry is becoming more and more extensive,and online education realized through ICT is developing in full swing.The influence of ICT...The application of information and communications technology(ICT)in the education industry is becoming more and more extensive,and online education realized through ICT is developing in full swing.The influence of ICT on online education consumer's choice behavior is the core issue of online education industry development research.The research on the interactive path and methods of information and online education consumer choice behavior is worth exploring and revealing.This study introduces the word-of-mouth factor as a new research variable under the framework of the Rational Choice Theory model(RCT)and the structural equation method to conduct empirical research and theoretical analysis to verify the validity of the hypothesis and model.The fifthGeneration mobile communication system(5 G)analyses the factors affecting online education consumer behavior choices based on the premise of ICT.Research on the path between ICT and choice behavior provides new ideas for online education consumer choice behavior research and ICT and content and provides a new scenario.This article is a cross-disciplinary research content in theory,and its innovation opens up a new path for the management of ICT research.The research results have innovative significance and value at both the theoretical and practical levels.展开更多
The research of Non-Orthogonal Multiple Access (NOMA) is extensively used to improve the capacity of networks beyond the fifth-generation. The recent merger of NOMA with ambient Backscatter Communication (BackCom), th...The research of Non-Orthogonal Multiple Access (NOMA) is extensively used to improve the capacity of networks beyond the fifth-generation. The recent merger of NOMA with ambient Backscatter Communication (BackCom), though opening new possibilities for massive connectivity, poses several challenges in dense wireless networks. One such challenge is the performance degradation of ambient BackCom in multi-cell NOMA networks under the effect of inter-cell interference. Driven by providing an efficient solution to the issue, this article proposes a new resource allocation framework that uses a duality theory approach. Specifically, the sum rate of the multi-cell network with backscatter tags and NOMA user equipment is maximized by formulating a joint optimization problem. To find the efficient base station transmit power and backscatter reflection coefficient in each cell, the original problem is first divided into two subproblems, and then the closed form solution is derived. A comparison with the Orthogonal Multiple Access (OMA) ambient BackCom and pure NOMA transmission has been provided. Simulation results of the proposed NOMA ambient BackCom indicate a significant improvement over the OMA ambient BackCom and pure NOMA in terms of sum-rate gains.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
Real-time and high-precision Fifth-generation mobile communication technology(5G)positioning is essential for establishing a wide-area and high-accuracy spatiotemporal reference framework in urban environments.However...Real-time and high-precision Fifth-generation mobile communication technology(5G)positioning is essential for establishing a wide-area and high-accuracy spatiotemporal reference framework in urban environments.However,a main challenge is the Non-Line-Of-Sight(NLOS)error significantly impact positioning accuracy,limiting the full deployment and application of 5G technology.In this study,a novel NLOS error mitigation method using Virtual Base-Station(VBS)-assisted algorithm is developed to enhance both kinematic and static positioning performance of 5G systems in complex urban environments.The proposed method consists of three modules:(1)a Time-Of-Arrival(TOA)positioning model,(2)a VBS generation method,and(3)a stable-state discrimination method.The TOA positioning model utilizes raw TOA measurements and a conventional four-station localization algorithm to estimate the location of user equipment.The VBS generation method optimizes Base-Station(BS)performance with particle filter combined with a random-distribution algorithm.The stable-state discrimination method employs the Augmented Dickey-Fuller(ADF)test to assess the stationarity of the feedback iteration process in VBS optimization.Several experiments are conducted in diverse scenario areas to evaluate the effectiveness,accuracy,and robustness of the proposed method.The results demonstrate that the proposed method significantly outperforms the traditional localization method,a 21.09%improvement in Three-Dimensional(3D)positioning accuracy.Compared to the state-of-the-art method,the proposed algorithm not only achieves slightly higher accuracy but,more importantly,reduces significantly the computation time.展开更多
The complexity and unpredictability of clear air turbulence(CAT)pose significant challenges to aviation safety.Accurate prediction of turbulence events is crucial for reducing flight accidents and economic losses.Howe...The complexity and unpredictability of clear air turbulence(CAT)pose significant challenges to aviation safety.Accurate prediction of turbulence events is crucial for reducing flight accidents and economic losses.However,traditional turbulence prediction methods,such as ensemble forecasting techniques,have certain limitations:they only consider turbulence data from the most recent period,making it difficult to capture the nonlinear relationships present in turbulence.This study proposes a turbulence forecasting model based on the K-nearest neighbor(KNN)algorithm,which uses a combination of eight CAT diagnostic features as the feature vector and introduces CAT diagnostic feature weights to improve prediction accuracy.The model calculates the results of seven years of CAT diagnostics from 125 to 500 hPa obtained from the ECMWF fifth-generation reanalysis dataset(ERA5)as feature vector inputs and combines them with the labels of Pilot Reports(PIREP)annotated data,where each sample contributes to the prediction result.By measuring the distance between the current CAT diagnostic variable and other variables,the model determines the climatically most similar neighbors and identifies the turbulence intensity category caused by the current variable.To evaluate the model’s performance in diagnosing high-altitude turbulence over Colorado,PIREP cases were randomly selected for analysis.The results show that the weighted KNN(W-KNN)model exhibits higher skill in turbulence prediction,and outperforms traditional prediction methods and other machine learning models(e.g.,Random Forest)in capturing moderate or greater(MOG)level turbulence.The performance of the model was confirmed by evaluating the receiver operating characteristic(ROC)curve,maximum True Skill Statistic(maxTSS=0.552),and reliability plot.A robust score(area under the curve:AUC=0.86)was obtained,and the model demonstrated sensitivity to seasonal and annual climate fluctuations.展开更多
In fifth-generation wireless communication system(5G),more connections are built between metaheuristics and electromagnetic equipment design.In this paper,we propose a self-adaptive grey wolf optimizer(SAGWO)combined ...In fifth-generation wireless communication system(5G),more connections are built between metaheuristics and electromagnetic equipment design.In this paper,we propose a self-adaptive grey wolf optimizer(SAGWO)combined with a novel optimization model of a 5G frequency selection surface(FSS)based on FSS unit nodes.SAGWO includes three improvement strategies,improving the initial distribution,increasing the randomness,and enhancing the local search,to accelerate the convergence and effectively avoid local optima.In benchmark tests,the proposed optimizer performs better than the five other optimization algorithms:original grey wolf optimizer(GWO),genetic algorithm(GA),particle swarm optimizer(PSO),improved grey wolf optimizer(IGWO),and selective opposition based grey wolf optimization(SOGWO).Due to its global searchability,SAGWO is suitable for solving the optimization problem of a 5G FSS that has a large design space.The combination of SAGWO and the new FSS optimization model can automatically obtain the shape of the FSS unit with electromagnetic interference shielding capability at the center operating frequency.To verify the performance of the proposed method,a double-layer ring FSS is designed with the purpose of providing electromagnetic interference shielding features at28 GHz.The results show that the optimized FSS has better electromagnetic interference shielding at the center frequency and has higher angular stability.Finally,a sample of the optimized FSS is fabricated and tested.展开更多
We propose a dual-module multiple-input multiple-output(MIMO)antenna for portable terminals.The operating bands of the handheld terminal antenna are 5G(3.4–3.8 GHz)and WLAN(5.150–5.925 GHz).Antenna elements of 5G an...We propose a dual-module multiple-input multiple-output(MIMO)antenna for portable terminals.The operating bands of the handheld terminal antenna are 5G(3.4–3.8 GHz)and WLAN(5.150–5.925 GHz).Antenna elements of 5G and WLAN are spaced to reduce coupling between antenna elements in the same module.The return loss of all antenna elements is larger than 6 dB.The isolation between all elements is larger than 14 dB.The radiation efficiency of the high-frequency antenna is greater than 50%,and the radiation efficiency of the low-frequency antenna is greater than 40%.The far-field gain of all elements is greater than 2.2 dBi.展开更多
Exploiting microwave photonic(MWP)techniques to generate and distribute high-frequency millimeter-wave(mm-wave)signals,termed mm-wave radio over fiber(m-RoF)signals,holds considerable potential for achieving highdensi...Exploiting microwave photonic(MWP)techniques to generate and distribute high-frequency millimeter-wave(mm-wave)signals,termed mm-wave radio over fiber(m-RoF)signals,holds considerable potential for achieving highdensity and high-capacity fifth-generation and beyond networks.Herein,we experimentally validate a broadband m-RoF uplink fronthaul transmission system using the MWP downconversion concept,which comprises receiving and processing radio-frequency(RF)signals in the unlicensed V-band at around 60 GHz.The proposed system harnesses the simple cascaded modulator topology,in which an ultrawideband off-the-shelf Mach–Zehnder modulator(MZM)renders a simplestructured remote radio head by directly encoding the broadband 60 GHz uplink RF signal into the optical carrier.The nonlinear transfer function of another MZM at the center unit is explored to achieve subharmonic downconversion using cost-effective low-frequency local oscillator signals.Based on proof-of-concept experiments,mm-wave four quadrature amplitude modulation orthogonal frequency-division multiplexing signals centered at frequencies ranging from 51 GHz to 70 GHz are successfully downconverted into signals at the intermediate frequency(IF)of 1.4 GHz.In the case of 1.2 m mm-wave,free-space,and 5 km m-RoF transmissions,the obtained IF signals with a total bandwidth of 2.4 GHz achieve a bit-to-error ratio performance lower than the 7%hard-decision forward error correction limit of 3.8×10^(−3).A gross bit rate of 10 Gbit/s can be achieved over a total spectrum of up to 10 GHz,which fully covers the globally unlicensed V-band of 57-66 GHz.展开更多
文摘POSSIBLY no other schoolreunion has aroused moreattention or had such apalpable ethos of com-merce than that of the BeijingFilm Institute class of 1978.
基金supported in part by Natural Science Foundation of Fujian Province(2021J05178)in part by the Scientific Research Foundation of Jimei University(ZQ2021001).
文摘In this paper,a novel wideband 8-element multiple-input and multiple-output(MIMO)antenna based on Booker’s relation is proposed for the fifth generation(5G)handset applications.The 8 antenna elements are arranged symmetrically along the two longer vertical side-edge frames of the handset.Each antenna element is composed of a monopole and a slot radiation structure,in which wideband characteristic covering 3140-5620MHz can be obtained.Note that the L-shaped monopole and the slot can be deemed as complementary counterparts approximatively.Furthermore,the Z-parameter of the proposed wideband antenna element is equivalent to the shunt impedance of monopole as well as slot radiator.Based on Booker’s relation,the wideband input impedance characteristic is therein achieved compared with conventional wideband technique such as multiresonance.Four L-shaped stubs as well as two slots etched on the ground plane are utilized to achieve acceptable isolation performance better than 13 dB,with total efficiency higher than 60%and envelope correlation coefficients(ECCs)lower than 0.1.The proposed antenna scheme can be a good candidate for 5G handset applications with the advantages of wideband,simple structure,high efficiency,and acceptable isolation performance.Also,the scheme might be a rewarding attempt to promote the Booker’s relation in the application of 5G terminal MIMO antenna designs.
基金supported by the National Key Research and Development Program of China(2020YFB1804900 and 2022YFE0210900)the Fundamental Research Funds for the Central Universities(2242022k60008 and 2242022k30003)+2 种基金the National Natural Science Foundation of China(62301152 and 61627801)the Youth Talent Promotion Foundation of Jiangsu Science and Technology Association(TJ-2023-074)the Startup Research Fund of Southeast University(RF1028623286).
文摘In this article,a single-board integrated millimeter-wave(mm-Wave)asymmetric full-digital beamforming(AFDBF)array is developed for beyond-fifth-generation(B5G)and sixth-generation(6G)communications.The proposed integrated array effectively addresses the challenge of arranging a large number of ports in a full-digital array by designing vertical connections in a three-dimensional space and successfully integrating full-digital transmitting(Tx)and receiving(Rx)arrays independently in a single board.Unlike the traditional symmetric array,the proposed asymmetric array is composed of an 8×8 Tx array arranged in a square shape and an 8+8 Rx array arranged in an L shape.The center-to-center distance between two adjacent elements is 0.54k0 for both the Tx and Rx arrays,where k0 is the free-space wavelength at 27 GHz.The proposed AFDBF array possesses a more compact structure and lower system hardware cost and power consumption compared with conventional brick-type full-digital arrays.In addition,the energy efficiency of the proposed AFDBF array outperforms that of a hybrid beamforming array.The measurement results indicate that the operating frequency band of the proposed array is 24.25–29.50 GHz.An eight-element linear array within the Tx array can achieve a scanning angle ranging from-47°to+47°in both the azimuth and the elevation planes,and the measured scanning range of each eight-element Rx array is–45°to+45°.The measured maximum effective isotropic radiated power(EIRP)of the eight-element Tx array is 43.2 dBm at 28.0 GHz(considering the saturation point).Furthermore,the measured error vector magnitude(EVM)is less than 3%when 64-quadrature amplitude modulation(QAM)waveforms are used.
基金This work was supported in part by the National Key Research and Development Program of China under Grant 2019YFB1803000in part by the Major Key Project of Peng Cheng Laboratory,Shenzhen,China,under Project PCL2021A01-2.
文摘This article presents an 8-element dual-polarized phased-array transceiver(TRX)front-end IC for millimeter-wave(mm-Wave)5G new radio(NR).Power enhancement technologies for power amplifiers(PA)in mm-Wave 5G phased-array TRX are discussed.A four-stage wideband high-power class-AB PA with distributed-active-transformer(DAT)power combining and multi-stage second-harmonic traps is proposed,ensuring the mitigated amplitude-to-phase(AM-PM)distortions across wide carrier frequencies without degrading transmitting(TX)power,gain and efficiency.TX and receiving(RX)switching is achieved by a matching network co-designed on-chip T/R switch.In each TRX element,6-bit 360°phase shifting and 6-bit 31.5-dB gain tuning are respectively achieved by the digital-controlled vector-modulated phase shifter(VMPS)and differential attenuator(ATT).Fabricated in 65-nm bulk complementary metal oxide semiconductor(CMOS),the proposed TRX demonstrates the measured peak TX/RX gains of 25.5/21.3 dB,covering the 24−29.5 GHz band.The measured peak TX OP1dB and power-added efficiency(PAE)are 20.8 dBm and 21.1%,respectively.The measured minimum RX NF is 4.1 dB.The TRX achieves an output power of 11.0−12.4 dBm and error vector magnitude(EVM)of 5%with 400-MHz 5G NR FR2 OFDM 64-QAM signals across 24−29.5 GHz,covering 3GPP 5G NR FR2 operating bands of n257,n258,and n261.
文摘In this study,fog simulations were conducted using the Fifth-Generation NCAR/Penn State Mesoscale Model (MM5) in and around the Yodo River Basin,Japan.The purpose is to investigate the MM5 performance of fog simulation for long-term periods.The simulations were performed for January,February,March,and July,2005 with a coarse 3-kin and a nested fine 1-km grid domains. Results of the simulations were compared with data from ten meteorological observatories,fog sampling site in Mt.Rokko,and visibility measurem...
基金supported by the National tural Science Foundation of ChinaNa[grant number 41974038]NaThe tional Key Research and Development Program of China[grant number 2018YFC0809804].
文摘NaGlobal vigation Satellite System(GNSS)positioning technology is widely used for its high precision,global,and all-weather service.However,in complex environments such as urban canyons,GNSS performance is often degraded due to signal occlusion and even fails to achieve positioning due to the insufficient visible satellites.Because of the characteristics of large band-width,low latency,and high Base Station(BS)density,the fifth-Generation mobile communication(5G)technology has gradually become a trend for positioning in cities while offering traditional communication service.To supply the communication demands of the User Equipment(UE),only one BS is usually considered to establish a connection with the UE during the BS construction.However,the positioning accuracy with a single BS in urban canyons will be significantly reduced.To further improve the positioning accuracy in such extreme scenarios,this paper proposes a simplified 5G/GNSS fusion positioning system architecture using observations from only a 5G BS and a GNSS satellite.In this system,the GNSS receiver is mounted on the 5G BS,and the measurements provided by the receiver are used to form the differential code and complete the position estimation.The positioning mathematical models of the system based on the original code and differential code are derived.Then,the impacts of the measurements noise and the time synchronization error on the positioning accuracy are analyzed theoretically.Finally,the positioning performance is investigated by a set of simulation experiments.Numerical results show that under the existing 5G measurement noise and 2 m’s code measurement noise,the improvement of the differential code based fusion positioning compared with the 5G-only positioning is more than 32%,which is also about 6%higher than the original code based fusion positioning.Besides,this improvement is not affected by the time synchronization error between the BS and the GNSS satellite.
基金The Social Development Projects of Jiangsu Science and Technology Department(No.BE2018704).
文摘In response to the downlink synchronization requirements of the user equipment(UE)or third-party radio equipment in fifth-generation(5G)mobile communication systems,a synchronization algorithm of primary synchroni-zation signal(PSS)was designed and developed in the 5G system based on block cross-correlation.According to the new characteristics of the 5G synchronization channel and broadcast channel,starting from the traditional downlink synchronization algorithm of long-term evolution(LTE),the detection performance of the algorithm under a low signal-to-noise ratio(SNR)is improved by introducing an incoherent accumulation,and the new scheme of joint coarse frequency offset estimation is used to improve the frequency offset estimation performance.Finally,the performance of the proposed synchronization algorithm is verified by conducting a simulation on a 5G downlink simulation platform based on MATLAB software.Simulation results show that the improved downlink synchronization algorithm has stable performance in the tapped delay line-C(TDL-C)and additive white Gaussian noise(AWGN)channels with large frequency deviation and low SNR.
基金We hereby acknowledge the financial support of the Ministry of Electronics and Information Technology(Meity),Government of India,in this research work.(Grant No.:PhD-MLA-4(96)/2015-2016).
文摘The analytical lower bound of Spectral Efficiency(SE)of downlink transmission of the Massive Multiple Input Multiple Output(Ma-MIMO)system is analyzed.In this paper,we derive some novel and approximate mathematical expressions for the lower bound of the SE of a Ma-MIMO with linear precoding schemes,i.e.,Minimum Mean Square Error(MMSE)and Zero-Forcing(ZF).For simulation analysis of the SE,we consider three joint users and antenna scheduling algorithms,namely,the semi-orthogonal,random,and distance-based user scheduling algorithms,whereas the antennas are selected based on Maximum Signal to Noise Ratio(MSNR)with scheduled users.The channel between the user and the transmitter is assumed to have characteristics of Small Scale Fading(SSF)and Large Scale Fading(LSF)with the Rayleigh fading model.We investigate the effect of the variation of transmitting SNR,the number of base station antennas(M),and the radius(R)of the cell area on the SE.We simulate the downlink transmission of Ma-MIMO and compare the simulation and analytical results.It is observed that the trends of variation of both results are similar to the variation of identical factors,and the difference between the simulated and analytical lower bounds of the SE is approximately 1-1.5 bits.The analytical lower bound is smaller than the simulation result.
基金supported by National Social Science Fund Youth Project“Research on the Group Behavior of‘Post-95’College Students Based on Complex Networks”of China(Project Number:17CKS047)。
文摘The application of information and communications technology(ICT)in the education industry is becoming more and more extensive,and online education realized through ICT is developing in full swing.The influence of ICT on online education consumer's choice behavior is the core issue of online education industry development research.The research on the interactive path and methods of information and online education consumer choice behavior is worth exploring and revealing.This study introduces the word-of-mouth factor as a new research variable under the framework of the Rational Choice Theory model(RCT)and the structural equation method to conduct empirical research and theoretical analysis to verify the validity of the hypothesis and model.The fifthGeneration mobile communication system(5 G)analyses the factors affecting online education consumer behavior choices based on the premise of ICT.Research on the path between ICT and choice behavior provides new ideas for online education consumer choice behavior research and ICT and content and provides a new scenario.This article is a cross-disciplinary research content in theory,and its innovation opens up a new path for the management of ICT research.The research results have innovative significance and value at both the theoretical and practical levels.
文摘The research of Non-Orthogonal Multiple Access (NOMA) is extensively used to improve the capacity of networks beyond the fifth-generation. The recent merger of NOMA with ambient Backscatter Communication (BackCom), though opening new possibilities for massive connectivity, poses several challenges in dense wireless networks. One such challenge is the performance degradation of ambient BackCom in multi-cell NOMA networks under the effect of inter-cell interference. Driven by providing an efficient solution to the issue, this article proposes a new resource allocation framework that uses a duality theory approach. Specifically, the sum rate of the multi-cell network with backscatter tags and NOMA user equipment is maximized by formulating a joint optimization problem. To find the efficient base station transmit power and backscatter reflection coefficient in each cell, the original problem is first divided into two subproblems, and then the closed form solution is derived. A comparison with the Orthogonal Multiple Access (OMA) ambient BackCom and pure NOMA transmission has been provided. Simulation results of the proposed NOMA ambient BackCom indicate a significant improvement over the OMA ambient BackCom and pure NOMA in terms of sum-rate gains.
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 China Mobile Group Device Co.,Ltd Fund(CMDC-202401967,CMDC-202402083).
文摘Real-time and high-precision Fifth-generation mobile communication technology(5G)positioning is essential for establishing a wide-area and high-accuracy spatiotemporal reference framework in urban environments.However,a main challenge is the Non-Line-Of-Sight(NLOS)error significantly impact positioning accuracy,limiting the full deployment and application of 5G technology.In this study,a novel NLOS error mitigation method using Virtual Base-Station(VBS)-assisted algorithm is developed to enhance both kinematic and static positioning performance of 5G systems in complex urban environments.The proposed method consists of three modules:(1)a Time-Of-Arrival(TOA)positioning model,(2)a VBS generation method,and(3)a stable-state discrimination method.The TOA positioning model utilizes raw TOA measurements and a conventional four-station localization algorithm to estimate the location of user equipment.The VBS generation method optimizes Base-Station(BS)performance with particle filter combined with a random-distribution algorithm.The stable-state discrimination method employs the Augmented Dickey-Fuller(ADF)test to assess the stationarity of the feedback iteration process in VBS optimization.Several experiments are conducted in diverse scenario areas to evaluate the effectiveness,accuracy,and robustness of the proposed method.The results demonstrate that the proposed method significantly outperforms the traditional localization method,a 21.09%improvement in Three-Dimensional(3D)positioning accuracy.Compared to the state-of-the-art method,the proposed algorithm not only achieves slightly higher accuracy but,more importantly,reduces significantly the computation time.
基金Supported by the Nanjing University of Aeronautics and Astronautics(KFB2305601).
文摘The complexity and unpredictability of clear air turbulence(CAT)pose significant challenges to aviation safety.Accurate prediction of turbulence events is crucial for reducing flight accidents and economic losses.However,traditional turbulence prediction methods,such as ensemble forecasting techniques,have certain limitations:they only consider turbulence data from the most recent period,making it difficult to capture the nonlinear relationships present in turbulence.This study proposes a turbulence forecasting model based on the K-nearest neighbor(KNN)algorithm,which uses a combination of eight CAT diagnostic features as the feature vector and introduces CAT diagnostic feature weights to improve prediction accuracy.The model calculates the results of seven years of CAT diagnostics from 125 to 500 hPa obtained from the ECMWF fifth-generation reanalysis dataset(ERA5)as feature vector inputs and combines them with the labels of Pilot Reports(PIREP)annotated data,where each sample contributes to the prediction result.By measuring the distance between the current CAT diagnostic variable and other variables,the model determines the climatically most similar neighbors and identifies the turbulence intensity category caused by the current variable.To evaluate the model’s performance in diagnosing high-altitude turbulence over Colorado,PIREP cases were randomly selected for analysis.The results show that the weighted KNN(W-KNN)model exhibits higher skill in turbulence prediction,and outperforms traditional prediction methods and other machine learning models(e.g.,Random Forest)in capturing moderate or greater(MOG)level turbulence.The performance of the model was confirmed by evaluating the receiver operating characteristic(ROC)curve,maximum True Skill Statistic(maxTSS=0.552),and reliability plot.A robust score(area under the curve:AUC=0.86)was obtained,and the model demonstrated sensitivity to seasonal and annual climate fluctuations.
基金Project supported by the Guangdong Basic and Applied Basic Research FoundationChina(No.2019A1515011783)the National Natural Science Foundation of China(No.52075184)。
文摘In fifth-generation wireless communication system(5G),more connections are built between metaheuristics and electromagnetic equipment design.In this paper,we propose a self-adaptive grey wolf optimizer(SAGWO)combined with a novel optimization model of a 5G frequency selection surface(FSS)based on FSS unit nodes.SAGWO includes three improvement strategies,improving the initial distribution,increasing the randomness,and enhancing the local search,to accelerate the convergence and effectively avoid local optima.In benchmark tests,the proposed optimizer performs better than the five other optimization algorithms:original grey wolf optimizer(GWO),genetic algorithm(GA),particle swarm optimizer(PSO),improved grey wolf optimizer(IGWO),and selective opposition based grey wolf optimization(SOGWO).Due to its global searchability,SAGWO is suitable for solving the optimization problem of a 5G FSS that has a large design space.The combination of SAGWO and the new FSS optimization model can automatically obtain the shape of the FSS unit with electromagnetic interference shielding capability at the center operating frequency.To verify the performance of the proposed method,a double-layer ring FSS is designed with the purpose of providing electromagnetic interference shielding features at28 GHz.The results show that the optimized FSS has better electromagnetic interference shielding at the center frequency and has higher angular stability.Finally,a sample of the optimized FSS is fabricated and tested.
基金supported by the National and Local Joint Engineering Laboratory of RF Integration and Micro-Assembly Technology,China(No.KFJJ20170206)the Research Project of Nanjing University of Posts and Telecommunications,China(No.208035)the University of Macao,China(No.CPG2019-00024-FST)。
文摘We propose a dual-module multiple-input multiple-output(MIMO)antenna for portable terminals.The operating bands of the handheld terminal antenna are 5G(3.4–3.8 GHz)and WLAN(5.150–5.925 GHz).Antenna elements of 5G and WLAN are spaced to reduce coupling between antenna elements in the same module.The return loss of all antenna elements is larger than 6 dB.The isolation between all elements is larger than 14 dB.The radiation efficiency of the high-frequency antenna is greater than 50%,and the radiation efficiency of the low-frequency antenna is greater than 40%.The far-field gain of all elements is greater than 2.2 dBi.
文摘Exploiting microwave photonic(MWP)techniques to generate and distribute high-frequency millimeter-wave(mm-wave)signals,termed mm-wave radio over fiber(m-RoF)signals,holds considerable potential for achieving highdensity and high-capacity fifth-generation and beyond networks.Herein,we experimentally validate a broadband m-RoF uplink fronthaul transmission system using the MWP downconversion concept,which comprises receiving and processing radio-frequency(RF)signals in the unlicensed V-band at around 60 GHz.The proposed system harnesses the simple cascaded modulator topology,in which an ultrawideband off-the-shelf Mach–Zehnder modulator(MZM)renders a simplestructured remote radio head by directly encoding the broadband 60 GHz uplink RF signal into the optical carrier.The nonlinear transfer function of another MZM at the center unit is explored to achieve subharmonic downconversion using cost-effective low-frequency local oscillator signals.Based on proof-of-concept experiments,mm-wave four quadrature amplitude modulation orthogonal frequency-division multiplexing signals centered at frequencies ranging from 51 GHz to 70 GHz are successfully downconverted into signals at the intermediate frequency(IF)of 1.4 GHz.In the case of 1.2 m mm-wave,free-space,and 5 km m-RoF transmissions,the obtained IF signals with a total bandwidth of 2.4 GHz achieve a bit-to-error ratio performance lower than the 7%hard-decision forward error correction limit of 3.8×10^(−3).A gross bit rate of 10 Gbit/s can be achieved over a total spectrum of up to 10 GHz,which fully covers the globally unlicensed V-band of 57-66 GHz.
