Recently,unmanned aerial vehicle(UAV)-aided free-space optical(FSO)communication has attracted widespread attentions.However,most of the existing research focuses on communication performance only.The authors investig...Recently,unmanned aerial vehicle(UAV)-aided free-space optical(FSO)communication has attracted widespread attentions.However,most of the existing research focuses on communication performance only.The authors investigate the integrated scheduling of communication,sensing,and control for UAV-aided FSO communication systems.Initially,a sensing-control model is established via the control theory.Moreover,an FSO communication channel model is established by considering the effects of atmospheric loss,atmospheric turbulence,geometrical loss,and angle-of-arrival fluctuation.Then,the relationship between the motion control of the UAV and radial displacement is obtained to link the control aspect and communication aspect.Assuming that the base station has instantaneous channel state information(CSI)or statistical CSI,the thresholds of the sensing-control pattern activation are designed,respectively.Finally,an integrated scheduling scheme for performing communication,sensing,and control is proposed.Numerical results indicate that,compared with conventional time-triggered scheme,the proposed integrated scheduling scheme obtains comparable communication and control performance,but reduces the sensing consumed power by 52.46%.展开更多
In this paper,we propose a sub-6GHz channel assisted hybrid beamforming(HBF)for mmWave system under both line-of-sight(LOS)and non-line-of-sight(NLOS)scenarios without mmWave channel estimation.Meanwhile,we resort to ...In this paper,we propose a sub-6GHz channel assisted hybrid beamforming(HBF)for mmWave system under both line-of-sight(LOS)and non-line-of-sight(NLOS)scenarios without mmWave channel estimation.Meanwhile,we resort to the selfsupervised approach to eliminate the need for labels,thus avoiding the accompanied high cost of data collection and annotation.We first construct the dense connection network(DCnet)with three modules:the feature extraction module for extracting channel characteristic from a large amount of channel data,the feature fusion module for combining multidimensional features,and the prediction module for generating the HBF matrices.Next,we establish a lightweight network architecture,named as LDnet,to reduce the number of model parameters and computational complexity.The proposed sub-6GHz assisted approach eliminates mmWave pilot resources compared to the method using mmWave channel information directly.The simulation results indicate that the proposed DCnet and LDnet can achieve the spectral efficiency that is superior to the traditional orthogonal matching pursuit(OMP)algorithm by 13.66% and 10.44% under LOS scenarios and by 32.35% and 27.75% under NLOS scenarios,respectively.Moreover,the LDnet achieves 98.52% reduction in the number of model parameters and 22.93% reduction in computational complexity compared to DCnet.展开更多
In this paper,the performance of a two-way relay (TWR) mixed radio frequency/free space optical (RF/FSO) system with co-channel interference (CCI) is investigated.Different from interference-limited one-way relay (OWR...In this paper,the performance of a two-way relay (TWR) mixed radio frequency/free space optical (RF/FSO) system with co-channel interference (CCI) is investigated.Different from interference-limited one-way relay (OWR) system,CCIs should be considered at both relay and users in TWR system.Additionally,opportunistic user schedule is applied to select the user with the largest signal to interference plus noise ratio (SINR).Exact and asymptotic outage probability (OP) is derived.Approximate bit error rate (BER) is further presented to evaluate the overall performance.Simulation results show that the performance of a TWR system is dominated by the uplink or downlink whose performance is severer.展开更多
To improve the accuracy and efficiency of time-varying channels estimation algorithms for millimeter Wave(mmWave)massive Multiple-Input Multiple-Output(MIMO)systems in Internet of Vehicles(IoV)scenarios,the paper prop...To improve the accuracy and efficiency of time-varying channels estimation algorithms for millimeter Wave(mmWave)massive Multiple-Input Multiple-Output(MIMO)systems in Internet of Vehicles(IoV)scenarios,the paper proposes a deep learning(DL)algorithm,Squeeze-and-Excitation Attention Residual Network(SEARNet),which integrates Squeeze-and-Excitation Attention(SEAttention)mechanism and residual module.Specifically,SEARNet considers the channel information as an image matrix,and embeds a SEAttention module in residual module to construct the SEAttention-Residual block.Through a data-driven approach,SEARNet can effectively extract key information from the channel matrix using the SEAttention mechanism,thereby reducing noise interference and estimating the channel in an accurate and efficient manner.The simulation results show that compared to two traditional and two DL channel estimation algorithms,the proposed SEARNet can achieve a maximum reduction in normalized mean square error(NMSE)of 97.66%and 84.49%at SNR of-10 dB,78.18%at SNR of 5 dB,and 43.51%at SNR of 10 dB,respectively.展开更多
In this paper,we investigate a Recofigurable Intelligent Surface(RIS)-assisted Free-Space Optics-Radio Frequency(FSO-RF)mixed dual-hop communication system for Unmanned Aerial Vehicles(UAVs).In the first hop,a source ...In this paper,we investigate a Recofigurable Intelligent Surface(RIS)-assisted Free-Space Optics-Radio Frequency(FSO-RF)mixed dual-hop communication system for Unmanned Aerial Vehicles(UAVs).In the first hop,a source UAV transmits data to a relay UAV using the FSO technique.In the second hop,the relay UAV forwards data to a destination Mobile Station(MS)via an RF channel,with the RIS enhancing coverage and performance.The relay UAV operates in a Decode-and-Forward(DF)mode.As the main contribution,we provide a mathematical performance analysis of the RIS-assisted FSO-RF mixed dual-hop UAV system,evaluating outage probability,Bit-Error Rate(BER),and average capacity.The analysis accounts for factors such as atmospheric attenuation,turbulence,geometric losses,and link interruptions caused by UAV hovering behaviors.To the best of our knowledge,this is the first theoretical investigation of RIS-assisted FSO-RF mixed dual-hop UAV communication systems.Our analytical results show strong agreement with Monte Carlo simulation outcomes.Furthermore,simulation results demonstrate that RIS significantly enhances the performance of UAV-aided mixed RF/FSO systems,although performance saturation is observed due to uncertainties stemming from UAV hovering behavior.展开更多
In this paper,we study the orthogonal time frequency space signal transmission over multi-path channel in the presence of phase noise(PHN)at both sides of millimeter wave(mmWave)communication links.The statistics char...In this paper,we study the orthogonal time frequency space signal transmission over multi-path channel in the presence of phase noise(PHN)at both sides of millimeter wave(mmWave)communication links.The statistics characteristics of the PHN-induced common phase error and inter-Doppler interference are investigated.Then,a column-shaped pilot structure is designed,and training pilots are used to realize linear-complexity PHN tracking and compensation.Numerical results demonstrate that the proposed scheme enables the signal to noise ratio loss to be restrained within 1 dB in contrast to the no PHN case.展开更多
自由空间光通信正交频分复用(Free Space Optical-Orthogonal Frequency Division Multiplexing,FSO-OFDM)系统面对的主要问题是峰均比(PAPR)高而导致的信号失真。而选择性映射(Selected Mapping,SLM)算法可以有效解决FSO-OFDM系统中的...自由空间光通信正交频分复用(Free Space Optical-Orthogonal Frequency Division Multiplexing,FSO-OFDM)系统面对的主要问题是峰均比(PAPR)高而导致的信号失真。而选择性映射(Selected Mapping,SLM)算法可以有效解决FSO-OFDM系统中的峰均比问题。目前,对峰均比抑制算法的研究还主要集中在理论方面,而且主要在发端研究降低峰均比的方法,而很少有文献将其应用于实际的信道传输。所以对FSO-OFDM系统中峰均比抑制算法的具体实现,尤其是在接收端进行实际验证的方法就显得意义重大。文中通过仿真信道传输和硬件实验都验证了采用SLM算法后FSO-OFDM系统的抗噪声干扰性能增加,并验证了SLM算法应用于实际的有效性,且该实验结果也为降低PAPR的后续研究奠定了实验基础。展开更多
文摘Recently,unmanned aerial vehicle(UAV)-aided free-space optical(FSO)communication has attracted widespread attentions.However,most of the existing research focuses on communication performance only.The authors investigate the integrated scheduling of communication,sensing,and control for UAV-aided FSO communication systems.Initially,a sensing-control model is established via the control theory.Moreover,an FSO communication channel model is established by considering the effects of atmospheric loss,atmospheric turbulence,geometrical loss,and angle-of-arrival fluctuation.Then,the relationship between the motion control of the UAV and radial displacement is obtained to link the control aspect and communication aspect.Assuming that the base station has instantaneous channel state information(CSI)or statistical CSI,the thresholds of the sensing-control pattern activation are designed,respectively.Finally,an integrated scheduling scheme for performing communication,sensing,and control is proposed.Numerical results indicate that,compared with conventional time-triggered scheme,the proposed integrated scheduling scheme obtains comparable communication and control performance,but reduces the sensing consumed power by 52.46%.
基金supported in part by the National Natural Science Foundation of China under Grants 62325107,62341107,62261160650,and U23A20272in part by the Beijing Natural Science Foundation under Grant L222002.
文摘In this paper,we propose a sub-6GHz channel assisted hybrid beamforming(HBF)for mmWave system under both line-of-sight(LOS)and non-line-of-sight(NLOS)scenarios without mmWave channel estimation.Meanwhile,we resort to the selfsupervised approach to eliminate the need for labels,thus avoiding the accompanied high cost of data collection and annotation.We first construct the dense connection network(DCnet)with three modules:the feature extraction module for extracting channel characteristic from a large amount of channel data,the feature fusion module for combining multidimensional features,and the prediction module for generating the HBF matrices.Next,we establish a lightweight network architecture,named as LDnet,to reduce the number of model parameters and computational complexity.The proposed sub-6GHz assisted approach eliminates mmWave pilot resources compared to the method using mmWave channel information directly.The simulation results indicate that the proposed DCnet and LDnet can achieve the spectral efficiency that is superior to the traditional orthogonal matching pursuit(OMP)algorithm by 13.66% and 10.44% under LOS scenarios and by 32.35% and 27.75% under NLOS scenarios,respectively.Moreover,the LDnet achieves 98.52% reduction in the number of model parameters and 22.93% reduction in computational complexity compared to DCnet.
基金supported by the Natural Science Foundation of Jilin Province (No.YDZJ202401626ZYTS)。
文摘In this paper,the performance of a two-way relay (TWR) mixed radio frequency/free space optical (RF/FSO) system with co-channel interference (CCI) is investigated.Different from interference-limited one-way relay (OWR) system,CCIs should be considered at both relay and users in TWR system.Additionally,opportunistic user schedule is applied to select the user with the largest signal to interference plus noise ratio (SINR).Exact and asymptotic outage probability (OP) is derived.Approximate bit error rate (BER) is further presented to evaluate the overall performance.Simulation results show that the performance of a TWR system is dominated by the uplink or downlink whose performance is severer.
基金supported in part by the National Natural Science Foundation of China under Grants U2001213 and 62261024in part by National Key Research and Development Project under Grant 2020YFB1807204in part by Key Laboratory of Universal Wireless Communications(BUPT),Ministry of Education under Grant KFKT2022101.
文摘To improve the accuracy and efficiency of time-varying channels estimation algorithms for millimeter Wave(mmWave)massive Multiple-Input Multiple-Output(MIMO)systems in Internet of Vehicles(IoV)scenarios,the paper proposes a deep learning(DL)algorithm,Squeeze-and-Excitation Attention Residual Network(SEARNet),which integrates Squeeze-and-Excitation Attention(SEAttention)mechanism and residual module.Specifically,SEARNet considers the channel information as an image matrix,and embeds a SEAttention module in residual module to construct the SEAttention-Residual block.Through a data-driven approach,SEARNet can effectively extract key information from the channel matrix using the SEAttention mechanism,thereby reducing noise interference and estimating the channel in an accurate and efficient manner.The simulation results show that compared to two traditional and two DL channel estimation algorithms,the proposed SEARNet can achieve a maximum reduction in normalized mean square error(NMSE)of 97.66%and 84.49%at SNR of-10 dB,78.18%at SNR of 5 dB,and 43.51%at SNR of 10 dB,respectively.
基金supported in part by the National Research Foundation of Korea(NRF)funded by the Korea government(MSIT)under Grant NRF-2022R1I1A3073740in part by the MSIT(Ministry of Science and ICT),Korea,under the ITRC(Information Technology Research Center)support program(IITP-2024-RS-2024-00436406)supervised by the IITP(Institute for Information&Communications Technology Planning&Evaluation)+1 种基金in part by the Institute for Information and Communications Technology Promotion(IITP)Grant funded by the Korea Government(MSIP,Development of Cube Satellites Based on Core Technologies in Low Earth Orbit Satellite Communications)under Grant RS-2024-00396992in part by the Korea Research Institute for Defense Technology planning and advancement(KRIT)grant,funded by the Korea government(DAPA(Defense Acquisition Program Administration))(21-106-A00-007,Space-Layer Intelligent Communication Network Laboratory,2022).
文摘In this paper,we investigate a Recofigurable Intelligent Surface(RIS)-assisted Free-Space Optics-Radio Frequency(FSO-RF)mixed dual-hop communication system for Unmanned Aerial Vehicles(UAVs).In the first hop,a source UAV transmits data to a relay UAV using the FSO technique.In the second hop,the relay UAV forwards data to a destination Mobile Station(MS)via an RF channel,with the RIS enhancing coverage and performance.The relay UAV operates in a Decode-and-Forward(DF)mode.As the main contribution,we provide a mathematical performance analysis of the RIS-assisted FSO-RF mixed dual-hop UAV system,evaluating outage probability,Bit-Error Rate(BER),and average capacity.The analysis accounts for factors such as atmospheric attenuation,turbulence,geometric losses,and link interruptions caused by UAV hovering behaviors.To the best of our knowledge,this is the first theoretical investigation of RIS-assisted FSO-RF mixed dual-hop UAV communication systems.Our analytical results show strong agreement with Monte Carlo simulation outcomes.Furthermore,simulation results demonstrate that RIS significantly enhances the performance of UAV-aided mixed RF/FSO systems,although performance saturation is observed due to uncertainties stemming from UAV hovering behavior.
基金supported by the National Natural Science Foundation of China(62071097)the Sichuan Science and Technology Program(2023NSFSC0458).
文摘In this paper,we study the orthogonal time frequency space signal transmission over multi-path channel in the presence of phase noise(PHN)at both sides of millimeter wave(mmWave)communication links.The statistics characteristics of the PHN-induced common phase error and inter-Doppler interference are investigated.Then,a column-shaped pilot structure is designed,and training pilots are used to realize linear-complexity PHN tracking and compensation.Numerical results demonstrate that the proposed scheme enables the signal to noise ratio loss to be restrained within 1 dB in contrast to the no PHN case.
文摘自由空间光通信正交频分复用(Free Space Optical-Orthogonal Frequency Division Multiplexing,FSO-OFDM)系统面对的主要问题是峰均比(PAPR)高而导致的信号失真。而选择性映射(Selected Mapping,SLM)算法可以有效解决FSO-OFDM系统中的峰均比问题。目前,对峰均比抑制算法的研究还主要集中在理论方面,而且主要在发端研究降低峰均比的方法,而很少有文献将其应用于实际的信道传输。所以对FSO-OFDM系统中峰均比抑制算法的具体实现,尤其是在接收端进行实际验证的方法就显得意义重大。文中通过仿真信道传输和硬件实验都验证了采用SLM算法后FSO-OFDM系统的抗噪声干扰性能增加,并验证了SLM算法应用于实际的有效性,且该实验结果也为降低PAPR的后续研究奠定了实验基础。
