Wireless body area networks(WBANs)would benefit reasonably after the introduction of mmWaves in the communication.The characteristics like high data rate and reduced antenna size are crucial benefits.However,the drawb...Wireless body area networks(WBANs)would benefit reasonably after the introduction of mmWaves in the communication.The characteristics like high data rate and reduced antenna size are crucial benefits.However,the drawbacks of mmWaves like high pathloss and high interference can be reduced by use of spectrum switching.The paper proposes a method of spectrum switching for indoor applications over the frequency range of 5 GHz to 60 GHz based on SNR as a threshold.This helps to maximize the throughput and minimize the pathloss over varied distance between the transreceivers.The paper further discusses the effects of this frequency on beamforming.The accuracy of the object tracking during the beam alignment despite of the narrow bandwidth is maintained due to prediction of the mobile user equipment by Kalman filter.The results are supported by Matlab simulation of a mobile UE over a range of 100 m and the corresponding spectrum switching and beam alignment results are discussed.The object tracking model is built with the help of Gaussian random walk and the results show an error margin of less than 1 m which is within the threshold designed for the system.The paper also presents the challenges reflected on secondary parameters like directivity,energy consumption,and beamforming array structures.展开更多
5G增强移动宽带(enhanced mobile broadband,eMBB)场景对于频谱效率、系统容量提出了较高要求。传统技术无法带来相应的性能提升,拟引入大规模天线、毫米波通信等技术,结合应用异构网络,提高系统性能。同时,目前针对e MBB场景关键技术...5G增强移动宽带(enhanced mobile broadband,eMBB)场景对于频谱效率、系统容量提出了较高要求。传统技术无法带来相应的性能提升,拟引入大规模天线、毫米波通信等技术,结合应用异构网络,提高系统性能。同时,目前针对e MBB场景关键技术的仿真评估较少,无法从仿真的角度说明各项技术的性能优势。通过搭建系统级仿真平台,评估了不同天线数目下大规模天线的性能,并根据异构网络下的仿真结果,总结了工作在毫米波频段的微基站密度与接入偏移对系统性能的影响,对5G网络的参数配置和网络建设都具有很大的参考价值。展开更多
Millimeter wave(mmWave) communications of unmanned aerial vehicles(UAVs) have drawn dramatic attentions for its flexibility on a variety of applications.Recently,channel tracking base on the spatial features has been ...Millimeter wave(mmWave) communications of unmanned aerial vehicles(UAVs) have drawn dramatic attentions for its flexibility on a variety of applications.Recently,channel tracking base on the spatial features has been proposed to solve the problem of beam misalignments due to the UAV navigation.However,unstable beam pointing caused by the non-ideal beam tracking environment may impact the performance of mmWave systems significantly.In this paper,an improved beamforming method is presented to overcome this shortcoming.Firstly,the effect of the beam deviation is analyzed through the establishment of the equivalent data rate.Then,combining the quantification of spatial angle and the improved orthogonal matching pursuit(OMP) algorithm,an optimized beam corresponding to the beam deviation is obtained.Simulation results show that the optimized beam of the proposed approach can effectively improve the spectral efficiency without improving the complexity when the beam pointing is unstable.展开更多
Recently,intelligent reflecting surface(IRS)assisted mmWave networks are emerging,which bear the potential to address the blockage issue of the millimeter wave(mmWave)communication in a more cost-effective way.In part...Recently,intelligent reflecting surface(IRS)assisted mmWave networks are emerging,which bear the potential to address the blockage issue of the millimeter wave(mmWave)communication in a more cost-effective way.In particular,IRS is built by passive and programmable electromagnetic elements that can manipulate the mmWave propagation channel into a more favorable condition that is free of blockage via judicious joint base station(BS)-IRS transmission design.However,the coexistence of IRSs and mmWave BSs complicates the network architecture,and thus poses great challenges for efficient beam management(BM)that is one critical prerequisite for high performance mmWave networks.In this paper,we systematically evaluate the key issues and challenges of BM for IRS-assisted mmWave networks to bring insights into the future network design.Specifically,we carefully classify and discuss the extensibility and limitations of the existing BM of conventional mmWave towards the IRS-assisted new paradigm.Moreover,we propose a novel machine learning empowered BM framework for IRS-assisted networks with representative showcases,which processes environmental and mobility awareness to achieve highly efficient BM with significantly reduced system overhead.Finally,some interesting future directions are also suggested to inspire further researches.展开更多
In this paper, the performance of hybrid precoding is investigated for mmWave massive MIMO systems with different antenna arrays. The hybrid precoding with partially connected architecture (PCA) is adopted. The spectr...In this paper, the performance of hybrid precoding is investigated for mmWave massive MIMO systems with different antenna arrays. The hybrid precoding with partially connected architecture (PCA) is adopted. The spectral efficiency (SE) and received energy efficiency (EE) are investigated by considering four types of antenna arrays, including uniform linear array (ULA), uniform rectangular planar array (URPA), uniform hexagonal planar array (UHPA), and uniform circular planar array (UCPA), respectively. We focus on analysis at the antenna response vector and utilize the idea of orthogonal matching pursuit algorithm to seek the optimal hybrid precoder. Furthermore, the trade-off of precoding architectures is studied between SE and received EE. Simulation results show that if the uniform planar array antenna is more concentrated, the SE and receive EE will be higher. Considering SE and received EE, the performance of planar arrays outperform linear array. There exist different optimal radio-frequency chain numbers to maximize the SE for planar array and linear array. In addition, the PCA can achieve relatively higher received EE while the SE is close to the fully connected architecture and the full digital architecture.展开更多
The deep convolutional neural network(CNN)is exploited in this work to conduct the challenging channel estimation for mmWave massive multiple input multiple output(MIMO)systems.The inherent sparse features of the mmWa...The deep convolutional neural network(CNN)is exploited in this work to conduct the challenging channel estimation for mmWave massive multiple input multiple output(MIMO)systems.The inherent sparse features of the mmWave massive MIMO channels can be extracted and the sparse channel supports can be learnt by the multi-layer CNN-based network through training.Then accurate channel inference can be efficiently implemented using the trained network.The estimation accuracy and spectrum efficiency can be further improved by fully utilizing the spatial correlation among the sparse channel supports of different antennas.It is verified by simulation results that the proposed deep CNN-based scheme significantly outperforms the state-of-the-art benchmarks in both accuracy and spectrum efficiency.展开更多
Both ultra-reliable low latency and high-data-rate communications are required by connective vehicles. Millimeter wave(mm Wave) with large bandwidth is a key technology to support high-data-rate communications. In thi...Both ultra-reliable low latency and high-data-rate communications are required by connective vehicles. Millimeter wave(mm Wave) with large bandwidth is a key technology to support high-data-rate communications. In this paper, the 28 GHz wideband vehicle-to-infrastructure channel is characterized for the urban environment in a major street in Manhattan. The deployment of the transmitter and the receiver, as well as the traffic models, are selected by considering the recommendation by 3GPP TR 37.885. Ray tracing simulator with calibrated electromagnetic parameters is employed in this work to practically conduct intensive simulations. The 3D environment model is reconstructed from OpenStreetMap. The power delay profile, path loss, root-meansquare delay spread, K-factor and so on, are extracted from the calibrated simulation results. The evolution of the parameters, as well as their statistical properties, are analyzed and modeled. The work of this paper helps the researchers understand the propagation channel for designing mmWave technologies and communication system in a similar scenario.展开更多
Cluster-based channel model is the main stream of fifth generation mobile communications, thus the accuracy of clustering algorithm is important. Traditional Gaussian mixture model (GMM) does not consider the power in...Cluster-based channel model is the main stream of fifth generation mobile communications, thus the accuracy of clustering algorithm is important. Traditional Gaussian mixture model (GMM) does not consider the power information which is important for the channel multipath clustering. In this paper, a normalized power weighted GMM (PGMM) is introduced to model the channel multipath components (MPCs). With MPC power as a weighted factor, the PGMM can fit the MPCs in accordance with the cluster-based channel models. Firstly, expectation maximization (EM) algorithm is employed to optimize the PGMM parameters. Then, to further increase the searching ability of EM and choose the optimal number of components without resort to cross-validation, the variational Bayesian (VB) inference is employed. Finally, 28 GHz indoor channel measurement data is used to demonstrate the effectiveness of the PGMM clustering algorithm.展开更多
In a millimeter-wave(mmWave)Massive multiple-input multiple-output(MIMO)systems,full-digital beamforming(i.e.,connecting each antenna with a specific radio-frequency(RF)chain)becomes inefficient due to the hardware co...In a millimeter-wave(mmWave)Massive multiple-input multiple-output(MIMO)systems,full-digital beamforming(i.e.,connecting each antenna with a specific radio-frequency(RF)chain)becomes inefficient due to the hardware cost and power consumption.Therefore,hybrid analog and digital transceiver where the number of RF chains are much smaller than that of the antennas has drawn great research interest.In this work,we investigate the use of low-resolution analog-to-digital converters(ADCs)in the uplink of multi-user hybrid and full-digital mmWave Massive MIMO systems.To be specific,we compare the performance of full-digital minimum mean square error(MMSE)and hybrid MMSE beamforming in both sum rates and energy efficiency.Accurate approximations of sum rates and energy efficiency are provided for both schemes,which captures the dominant factors.The analytical results show that full-digital beamforming outperforms hybrid beamforming in terms of sum rates and requires only a small portion(γ)of antennas used by hybrid beamforming to achieve the same sum rates.We given sufficient condition for full-digital beamforming to outperform hybrid beamforming in terms of energy efficiency.Moreover,an algorithm is proposed to search for the optimal ADC resolution bits.Numerical results demonstrate the correctness of the analysis.展开更多
In this paper,we analyze a hybrid Heterogeneous Cellular Network(HCNet)framework by deploying millimeter Wave(mmWave)small cells with coexisting traditional sub-6GHz macro cells to achieve improved coverage and high d...In this paper,we analyze a hybrid Heterogeneous Cellular Network(HCNet)framework by deploying millimeter Wave(mmWave)small cells with coexisting traditional sub-6GHz macro cells to achieve improved coverage and high data rate.We consider randomly-deployed macro base stations throughout the network whereas mmWave Small Base Stations(SBSs)are deployed in the areas with high User Equipment(UE)density.Such user centric deployment of mmWave SBSs inevitably incurs correlation between UE and SBSs.For a realistic scenario where the UEs are distributed according to Poisson cluster process and directional beamforming with line-of-sight and non-line-of-sight transmissions is adopted for mmWave communication.By using tools from stochastic geometry,we develop an analytical framework to analyze various performance metrics in the downlink hybrid HCNets under biased received power association.For UE clustering we considered Thomas cluster process and derive expressions for the association probability,coverage probability,area spectral efficiency,and energy efficiency.We also provide Monte Carlo simulation results to validate the accuracy of the derived expressions.Furthermore,we analyze the impact of mmWave operating frequency,antenna gain,small cell biasing,and BSs density to get useful engineering insights into the performance of hybrid mmWave HCNets.Our results show that network performance is significantly improved by deploying millimeter wave SBS instead of microwave BS in hot spots.展开更多
Wireless channel characteristics have significant impacts on channel modeling,estimation,and communication performance.While the channel sparsity is an important characteristic of wireless channels.Utilizing the spars...Wireless channel characteristics have significant impacts on channel modeling,estimation,and communication performance.While the channel sparsity is an important characteristic of wireless channels.Utilizing the sparse nature of wireless channels can reduce the complexity of channel modeling and estimation,and improve system design and performance analysis.Compared with the traditional sub6 GHz channel,millimeter wave(mmWave)channel has been considered to be more sparse in existing researches.However,most research only assume that the mmWave channel is sparse,without providing quantitative analysis and evaluation.Therefore,this paper evaluates the sparsity of mmWave channels based on mmWave channel measurements.A vector network analyzer(VNA)-based mmWave channel sounder is developed to measure the channel at 28 GHz,and multi-scenario channel measurements are conducted.The Gini index,Rician𝐾factor and rootmean-square(RMS)delay spread are used to measure channel sparsity.Then,the key factors affecting mmWave channel sparsity are explored.It is found that antenna steering direction and scattering environment will affect the sparsity of mmWave channel.In addition,the impact of channel sparsity on channel eigenvalue and capacity is evaluated and analyzed.展开更多
Since the evolving standardization of cellular V2X(C-V2X)technologies is continuously developed by 3GPP,research on new radio(NR-V2X)has been on schedule by academic and industries.Though millimeter wave(mm Wave)frequ...Since the evolving standardization of cellular V2X(C-V2X)technologies is continuously developed by 3GPP,research on new radio(NR-V2X)has been on schedule by academic and industries.Though millimeter wave(mm Wave)frequency band is supposed to provide large transmission bandwidth,yet the development of mm Wave band in NR-V2X is still in preliminary stage.In this article,a comprehensive discussion of mm Wave NR-V2X is given covering trends,standardization landscape,and enabling technologies,aiming at tackling the challenge of channel modeling,directional channel access,beamforming and blockage management.The vision of mm Wave NR-V2X is to fully support the development of automated driving,holographic control display and improved in-car infotainment for the future.展开更多
基金The research was supported by National Science Foundation(Nos.1744272 and 1451629)The paper is an extension of the work submitted to IEEE Globecom Communications Conference。
文摘Wireless body area networks(WBANs)would benefit reasonably after the introduction of mmWaves in the communication.The characteristics like high data rate and reduced antenna size are crucial benefits.However,the drawbacks of mmWaves like high pathloss and high interference can be reduced by use of spectrum switching.The paper proposes a method of spectrum switching for indoor applications over the frequency range of 5 GHz to 60 GHz based on SNR as a threshold.This helps to maximize the throughput and minimize the pathloss over varied distance between the transreceivers.The paper further discusses the effects of this frequency on beamforming.The accuracy of the object tracking during the beam alignment despite of the narrow bandwidth is maintained due to prediction of the mobile user equipment by Kalman filter.The results are supported by Matlab simulation of a mobile UE over a range of 100 m and the corresponding spectrum switching and beam alignment results are discussed.The object tracking model is built with the help of Gaussian random walk and the results show an error margin of less than 1 m which is within the threshold designed for the system.The paper also presents the challenges reflected on secondary parameters like directivity,energy consumption,and beamforming array structures.
文摘5G增强移动宽带(enhanced mobile broadband,eMBB)场景对于频谱效率、系统容量提出了较高要求。传统技术无法带来相应的性能提升,拟引入大规模天线、毫米波通信等技术,结合应用异构网络,提高系统性能。同时,目前针对e MBB场景关键技术的仿真评估较少,无法从仿真的角度说明各项技术的性能优势。通过搭建系统级仿真平台,评估了不同天线数目下大规模天线的性能,并根据异构网络下的仿真结果,总结了工作在毫米波频段的微基站密度与接入偏移对系统性能的影响,对5G网络的参数配置和网络建设都具有很大的参考价值。
基金supported by Aeronautical Science Foundation of China(2017ZC52021)the Fundamental Research Funds for the Central Universities(NS2017066)+1 种基金the Foundation of Graduate Innovation Center in NUAA(kfjj20171501)China Postdoctoral Science Foundation Funded Project(2015M581791)
文摘Millimeter wave(mmWave) communications of unmanned aerial vehicles(UAVs) have drawn dramatic attentions for its flexibility on a variety of applications.Recently,channel tracking base on the spatial features has been proposed to solve the problem of beam misalignments due to the UAV navigation.However,unstable beam pointing caused by the non-ideal beam tracking environment may impact the performance of mmWave systems significantly.In this paper,an improved beamforming method is presented to overcome this shortcoming.Firstly,the effect of the beam deviation is analyzed through the establishment of the equivalent data rate.Then,combining the quantification of spatial angle and the improved orthogonal matching pursuit(OMP) algorithm,an optimized beam corresponding to the beam deviation is obtained.Simulation results show that the optimized beam of the proposed approach can effectively improve the spectral efficiency without improving the complexity when the beam pointing is unstable.
基金the National Natural Science Foundation of China under Grant 61790553,61901049,62071071the Fundamental Research Funds for the Central Universities(2019XD-A13).
文摘Recently,intelligent reflecting surface(IRS)assisted mmWave networks are emerging,which bear the potential to address the blockage issue of the millimeter wave(mmWave)communication in a more cost-effective way.In particular,IRS is built by passive and programmable electromagnetic elements that can manipulate the mmWave propagation channel into a more favorable condition that is free of blockage via judicious joint base station(BS)-IRS transmission design.However,the coexistence of IRSs and mmWave BSs complicates the network architecture,and thus poses great challenges for efficient beam management(BM)that is one critical prerequisite for high performance mmWave networks.In this paper,we systematically evaluate the key issues and challenges of BM for IRS-assisted mmWave networks to bring insights into the future network design.Specifically,we carefully classify and discuss the extensibility and limitations of the existing BM of conventional mmWave towards the IRS-assisted new paradigm.Moreover,we propose a novel machine learning empowered BM framework for IRS-assisted networks with representative showcases,which processes environmental and mobility awareness to achieve highly efficient BM with significantly reduced system overhead.Finally,some interesting future directions are also suggested to inspire further researches.
基金supported by the National Natural Science Foundation of China (No.61961018)the Jiangxi Province Foundation for Distinguished Young Scholar (No.20192BCB23013)+1 种基金the Jiangxi Province Natural Science Foundation of China (No.20171BAB202001, 20192ACB21003)the Science Program of Jiangxi Educational Committee (No.GJJ180307)
文摘In this paper, the performance of hybrid precoding is investigated for mmWave massive MIMO systems with different antenna arrays. The hybrid precoding with partially connected architecture (PCA) is adopted. The spectral efficiency (SE) and received energy efficiency (EE) are investigated by considering four types of antenna arrays, including uniform linear array (ULA), uniform rectangular planar array (URPA), uniform hexagonal planar array (UHPA), and uniform circular planar array (UCPA), respectively. We focus on analysis at the antenna response vector and utilize the idea of orthogonal matching pursuit algorithm to seek the optimal hybrid precoder. Furthermore, the trade-off of precoding architectures is studied between SE and received EE. Simulation results show that if the uniform planar array antenna is more concentrated, the SE and receive EE will be higher. Considering SE and received EE, the performance of planar arrays outperform linear array. There exist different optimal radio-frequency chain numbers to maximize the SE for planar array and linear array. In addition, the PCA can achieve relatively higher received EE while the SE is close to the fully connected architecture and the full digital architecture.
基金This work is supported in part by the National Natural Science Foundation of China under grants 61901403,61971366 and 61971365in part by the Youth Innovation Fund of Xiamen under grant 3502Z20206039in part by the Natural Science Foundation of Fujian Province of China under grant 2019J05001.
文摘The deep convolutional neural network(CNN)is exploited in this work to conduct the challenging channel estimation for mmWave massive multiple input multiple output(MIMO)systems.The inherent sparse features of the mmWave massive MIMO channels can be extracted and the sparse channel supports can be learnt by the multi-layer CNN-based network through training.Then accurate channel inference can be efficiently implemented using the trained network.The estimation accuracy and spectrum efficiency can be further improved by fully utilizing the spatial correlation among the sparse channel supports of different antennas.It is verified by simulation results that the proposed deep CNN-based scheme significantly outperforms the state-of-the-art benchmarks in both accuracy and spectrum efficiency.
基金supported by Institute for Information & communications Technology Promotion(IITP) grant funded by the Korea government(MSIT) (No. 2018-0-00792, QoE improvement of open Wi-Fi on public transportation for the reduction of communication expense)
文摘Both ultra-reliable low latency and high-data-rate communications are required by connective vehicles. Millimeter wave(mm Wave) with large bandwidth is a key technology to support high-data-rate communications. In this paper, the 28 GHz wideband vehicle-to-infrastructure channel is characterized for the urban environment in a major street in Manhattan. The deployment of the transmitter and the receiver, as well as the traffic models, are selected by considering the recommendation by 3GPP TR 37.885. Ray tracing simulator with calibrated electromagnetic parameters is employed in this work to practically conduct intensive simulations. The 3D environment model is reconstructed from OpenStreetMap. The power delay profile, path loss, root-meansquare delay spread, K-factor and so on, are extracted from the calibrated simulation results. The evolution of the parameters, as well as their statistical properties, are analyzed and modeled. The work of this paper helps the researchers understand the propagation channel for designing mmWave technologies and communication system in a similar scenario.
基金supported by National Science and Technology Major Program of the Ministry of Science and Technology (No.2018ZX03001031)Key program of Beijing Municipal Natural Science Foundation (No. L172030)+2 种基金Beijing Municipal Science & Technology Commission Project (No. Z171100005217001)Key Project of State Key Lab of Networking and Switching Technology (NST20170205)National Key Technology Research and Development Program of the Ministry of Science and Technology of China (NO. 2012BAF14B01)
文摘Cluster-based channel model is the main stream of fifth generation mobile communications, thus the accuracy of clustering algorithm is important. Traditional Gaussian mixture model (GMM) does not consider the power information which is important for the channel multipath clustering. In this paper, a normalized power weighted GMM (PGMM) is introduced to model the channel multipath components (MPCs). With MPC power as a weighted factor, the PGMM can fit the MPCs in accordance with the cluster-based channel models. Firstly, expectation maximization (EM) algorithm is employed to optimize the PGMM parameters. Then, to further increase the searching ability of EM and choose the optimal number of components without resort to cross-validation, the variational Bayesian (VB) inference is employed. Finally, 28 GHz indoor channel measurement data is used to demonstrate the effectiveness of the PGMM clustering algorithm.
基金supported in part by the Key Research&Development Plan of Jiangsu Province(No.BE2018108)National Nature Science Foundation of China(Nos.61701198&61772243)+3 种基金Nature Science Foundation of Jiangsu Province(No.BK20170557)Nature Science Foundation for Higher Education Institutions of Jiangsu Province of China(No.17KJB510009)the open research fund of National Mobile Communications Research Laboratory,Southeast University(No.2018D13)Young Talent Project of Jiangsu University and Postgraduate Research&Practice Innovation Program of Jiangsu Province(No.SJCX18_0742)
文摘In a millimeter-wave(mmWave)Massive multiple-input multiple-output(MIMO)systems,full-digital beamforming(i.e.,connecting each antenna with a specific radio-frequency(RF)chain)becomes inefficient due to the hardware cost and power consumption.Therefore,hybrid analog and digital transceiver where the number of RF chains are much smaller than that of the antennas has drawn great research interest.In this work,we investigate the use of low-resolution analog-to-digital converters(ADCs)in the uplink of multi-user hybrid and full-digital mmWave Massive MIMO systems.To be specific,we compare the performance of full-digital minimum mean square error(MMSE)and hybrid MMSE beamforming in both sum rates and energy efficiency.Accurate approximations of sum rates and energy efficiency are provided for both schemes,which captures the dominant factors.The analytical results show that full-digital beamforming outperforms hybrid beamforming in terms of sum rates and requires only a small portion(γ)of antennas used by hybrid beamforming to achieve the same sum rates.We given sufficient condition for full-digital beamforming to outperform hybrid beamforming in terms of energy efficiency.Moreover,an algorithm is proposed to search for the optimal ADC resolution bits.Numerical results demonstrate the correctness of the analysis.
文摘In this paper,we analyze a hybrid Heterogeneous Cellular Network(HCNet)framework by deploying millimeter Wave(mmWave)small cells with coexisting traditional sub-6GHz macro cells to achieve improved coverage and high data rate.We consider randomly-deployed macro base stations throughout the network whereas mmWave Small Base Stations(SBSs)are deployed in the areas with high User Equipment(UE)density.Such user centric deployment of mmWave SBSs inevitably incurs correlation between UE and SBSs.For a realistic scenario where the UEs are distributed according to Poisson cluster process and directional beamforming with line-of-sight and non-line-of-sight transmissions is adopted for mmWave communication.By using tools from stochastic geometry,we develop an analytical framework to analyze various performance metrics in the downlink hybrid HCNets under biased received power association.For UE clustering we considered Thomas cluster process and derive expressions for the association probability,coverage probability,area spectral efficiency,and energy efficiency.We also provide Monte Carlo simulation results to validate the accuracy of the derived expressions.Furthermore,we analyze the impact of mmWave operating frequency,antenna gain,small cell biasing,and BSs density to get useful engineering insights into the performance of hybrid mmWave HCNets.Our results show that network performance is significantly improved by deploying millimeter wave SBS instead of microwave BS in hot spots.
基金supported by National Key R&D Program of China under Grant 2022YFF0608103the National Natural Science Foundation of China under Grant 61922012+1 种基金the Science and Technology Program of State Administration for Market Regulation under Grant 2021MK155the Fundamental Funds of National Institute of Metrology under Grant AKYZD2116-2.
文摘Wireless channel characteristics have significant impacts on channel modeling,estimation,and communication performance.While the channel sparsity is an important characteristic of wireless channels.Utilizing the sparse nature of wireless channels can reduce the complexity of channel modeling and estimation,and improve system design and performance analysis.Compared with the traditional sub6 GHz channel,millimeter wave(mmWave)channel has been considered to be more sparse in existing researches.However,most research only assume that the mmWave channel is sparse,without providing quantitative analysis and evaluation.Therefore,this paper evaluates the sparsity of mmWave channels based on mmWave channel measurements.A vector network analyzer(VNA)-based mmWave channel sounder is developed to measure the channel at 28 GHz,and multi-scenario channel measurements are conducted.The Gini index,Rician𝐾factor and rootmean-square(RMS)delay spread are used to measure channel sparsity.Then,the key factors affecting mmWave channel sparsity are explored.It is found that antenna steering direction and scattering environment will affect the sparsity of mmWave channel.In addition,the impact of channel sparsity on channel eigenvalue and capacity is evaluated and analyzed.
基金supported by the National Key Research and Development Program of China(2020YFB1807900)the National Natural Science Foundation of China(61931005,62001051)。
文摘Since the evolving standardization of cellular V2X(C-V2X)technologies is continuously developed by 3GPP,research on new radio(NR-V2X)has been on schedule by academic and industries.Though millimeter wave(mm Wave)frequency band is supposed to provide large transmission bandwidth,yet the development of mm Wave band in NR-V2X is still in preliminary stage.In this article,a comprehensive discussion of mm Wave NR-V2X is given covering trends,standardization landscape,and enabling technologies,aiming at tackling the challenge of channel modeling,directional channel access,beamforming and blockage management.The vision of mm Wave NR-V2X is to fully support the development of automated driving,holographic control display and improved in-car infotainment for the future.
