Free space optical(FSO)communication has recently aroused great interest in academia due to its unique features,such as large transmission band,high data rates,and strong anti-electromagnetic interference.With the aim...Free space optical(FSO)communication has recently aroused great interest in academia due to its unique features,such as large transmission band,high data rates,and strong anti-electromagnetic interference.With the aim of evaluating the performance of an FSO communication system and extending the line-of-sight transmission distance,we propose an unmanned aerial vehicle(UAV)-assisted dual-hop FSO communication system equipped with amplifyand-forward protocol at the relay node.Specifically,we consider impairments of atmospheric absorption,pointing errors,atmospheric turbulence,and link interruptions due to angle-of-arrival fluctuations in the relay system.The Gamma-Gamma and Malaga distributions are used to model the influence of atmospheric turbulence on the source-to-UAV and UAVto-destination links,respectively.We derive closedform expressions of the probability density function(PDF)and cumulative distribution function(CDF)for the proposed communication system,in terms of the Meijer-G function.Based on the precise PDF and CDF,analytical expressions for the outage probability,average bit error rate,and ergodic capacity are proposed with the aid of the extended generalized bivariate Fox’s H function.Finally,we show that there is a match between the analytical results and numerical results,and we analyze the influence of the system and channel parameters on the performance.展开更多
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
Supervisory Control and Data Acquisition （SCADA） is used broadly to portray control and management solutions in a wide range of industries. SCADA system failure may lead to disastrous consequences since the health a...Supervisory Control and Data Acquisition （SCADA） is used broadly to portray control and management solutions in a wide range of industries. SCADA system failure may lead to disastrous consequences since the health and the safety of the public as the economic viability of the community it serves depends on it. After its introduction in DPDC over a decade ago, the SCADA system hardly had any performance upgradation. Currently, the microwave link in SCADA Communication is observing problems that are rendering the entire structure obsolete. This paper revises the possibility to implement a new communication technology and proposes Free Space Optical （FSO） communication to enhance SCADA system reliability. FSO refers to the transmission of modulated visible or infrared （IR） beams through the air to obtain optical communication. Like optical fiber, FSO also uses lasers to transmit data, but instead of enclosing the data stream in a glass fiber, the data is transmitted through the air. It is a secure, cost-effective alternative to other wireless connectivity options.展开更多
There is growing global interest in establishing free-space optical(FSO)communication links,such as groundsatellite links(GSLs)of at least hundreds of kilometers,intersatellite links of thousands of kilometers,and fut...There is growing global interest in establishing free-space optical(FSO)communication links,such as groundsatellite links(GSLs)of at least hundreds of kilometers,intersatellite links of thousands of kilometers,and future deep space links of much greater dimensions.Enabling outdoor wireless FSO communication systems to be utilized during daylight hours can increase their availability in space-air-ground networks;however,this is usually accompanied by incoherent background radiation that impairs the signal-to-noise ratio(SNR)and bit error rate(BER).Therefore,a preliminary review of the background noise is required before constructing ground terminals with a suitable SNR in a harsh environment with high levels of solar noise.Herein,we evaluated the background noise that sunlight provides to ground terminals and quantitatively examined its impact on the SNR,communication performance,and beacon detection accuracy of the developed all-free-space ground terminal.Furthermore,we present the results of a daytime demonstration of a 7-km terrestrial free-space optical communication link by employing our ground terminal that was designed based on these analyses.The results verified that 2.5-Gbps data transmission up to 7 km is feasible,even in expected daytime satellite tracking scenarios with high background noise,by the developed system with spectral and spatial filtering to achieve an acceptable SNR.The background noise results of our research are anticipated to further the research on quantum communication networks,light detection and ranging(LiDAR),and green energy technologies.展开更多
Studying orbital angular momentum（OAM） spectra is important for analyzing crosstalk in free-space optical（FSO）communication systems. This work offers a new method of simplifying the expressions for the OAM spectra...Studying orbital angular momentum（OAM） spectra is important for analyzing crosstalk in free-space optical（FSO）communication systems. This work offers a new method of simplifying the expressions for the OAM spectra of Laguerre-Gaussian（LG） beams under both weak/medium and strong atmospheric turbulences. We propose fixing the radius to the extreme point of the intensity distribution, review the expression for the OAM spectrum under weak/medium turbulence,derive the OAM spectrum expression for an LG beam under strong turbulence, and simplify both of them to concise forms.Then, we investigate the accuracy of the simplified expressions through simulations. We find that the simplified expressions permit accurate calculation of the OAM spectrum for large transmitted OAM numbers under any type of turbulence. Finally,we use the simplified expressions to analytically address the broadening of the OAM spectrum caused by atmospheric turbulence. This work should contribute to the concise theoretical derivation of analytical expressions for OAM channel matrices for FSO-OAM communications and the analytical study of the laws governing OAM spectra.展开更多
We analyzed the performance of a freespace optical(FSO)system in this study,considering the combined effects of atmospheric turbulence,fog absorption,and pointing errors.The impacts of atmospheric turbulence and foggy...We analyzed the performance of a freespace optical(FSO)system in this study,considering the combined effects of atmospheric turbulence,fog absorption,and pointing errors.The impacts of atmospheric turbulence and foggy absorption were modeled using the Fisher-Snedecor F distribution and the Gamma distribution,respectively.Next,we derived the probability density function(PDF)and cumulative probability density function of the optical system under these combined effects.Based on these statistical findings,closed-form expressions for various system metrics,such as outage probability,average bit error rate(BER),and ergodic capacity,were derived.Furthermore,we used a deep neural network(DNN)to predict the ergodic capacity of the system,achieving reduced running time and improved accuracy.Finally,the accuracy of the prediction results was validated by comparing them with the analytical results.展开更多
This paper explores the ergodic channel capacity of multiple-input single-output(MISO)free-space optical(FSO)communication systems,assisted by(optical)re-configurable intelligent surfaces[(O)RIS],made of concave refle...This paper explores the ergodic channel capacity of multiple-input single-output(MISO)free-space optical(FSO)communication systems,assisted by(optical)re-configurable intelligent surfaces[(O)RIS],made of concave reflectors.On the one hand,RIS technology mitigates dead zones in communication systems.Additionally,it increases the data rate and communication range,enhances the communication channel by making it intelligent,and improves the system’s capacity.Finally,the RIS technology improves the spectrum and energy efficiencies of the considered systems.On the other hand,transmitting diversity mitigates deep fade and helps to achieve beamforming to regulate the beam sent in a specific direction.Finally,multiple light sources help to send different versions of the same information at other time slots.Furthermore,compared to flat reflectors,concave mirrors provide economic advantages enabled by their natural shape,which helps converge the impinging light beams into the same focal point.In this paper,we harness the full potential of ORIS and MISO technologies in an FSO system by exploiting the hollow of concave reflectors to focus the reflected beams on a single user.We derive an approximated closed-form expression,provide results of the proposed ORIS-aided FSO systems’ergodic channel capacity,and discuss the suitable type of concave reflector.These results show that all types of concave mirrors provide similar results except when the thickness of the reflector is large enough to impact the reflected light.展开更多
文摘Free space optical(FSO)communication has recently aroused great interest in academia due to its unique features,such as large transmission band,high data rates,and strong anti-electromagnetic interference.With the aim of evaluating the performance of an FSO communication system and extending the line-of-sight transmission distance,we propose an unmanned aerial vehicle(UAV)-assisted dual-hop FSO communication system equipped with amplifyand-forward protocol at the relay node.Specifically,we consider impairments of atmospheric absorption,pointing errors,atmospheric turbulence,and link interruptions due to angle-of-arrival fluctuations in the relay system.The Gamma-Gamma and Malaga distributions are used to model the influence of atmospheric turbulence on the source-to-UAV and UAVto-destination links,respectively.We derive closedform expressions of the probability density function(PDF)and cumulative distribution function(CDF)for the proposed communication system,in terms of the Meijer-G function.Based on the precise PDF and CDF,analytical expressions for the outage probability,average bit error rate,and ergodic capacity are proposed with the aid of the extended generalized bivariate Fox’s H function.Finally,we show that there is a match between the analytical results and numerical results,and we analyze the influence of the system and channel parameters on the performance.
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%.
文摘Supervisory Control and Data Acquisition （SCADA） is used broadly to portray control and management solutions in a wide range of industries. SCADA system failure may lead to disastrous consequences since the health and the safety of the public as the economic viability of the community it serves depends on it. After its introduction in DPDC over a decade ago, the SCADA system hardly had any performance upgradation. Currently, the microwave link in SCADA Communication is observing problems that are rendering the entire structure obsolete. This paper revises the possibility to implement a new communication technology and proposes Free Space Optical （FSO） communication to enhance SCADA system reliability. FSO refers to the transmission of modulated visible or infrared （IR） beams through the air to obtain optical communication. Like optical fiber, FSO also uses lasers to transmit data, but instead of enclosing the data stream in a glass fiber, the data is transmitted through the air. It is a secure, cost-effective alternative to other wireless connectivity options.
文摘There is growing global interest in establishing free-space optical(FSO)communication links,such as groundsatellite links(GSLs)of at least hundreds of kilometers,intersatellite links of thousands of kilometers,and future deep space links of much greater dimensions.Enabling outdoor wireless FSO communication systems to be utilized during daylight hours can increase their availability in space-air-ground networks;however,this is usually accompanied by incoherent background radiation that impairs the signal-to-noise ratio(SNR)and bit error rate(BER).Therefore,a preliminary review of the background noise is required before constructing ground terminals with a suitable SNR in a harsh environment with high levels of solar noise.Herein,we evaluated the background noise that sunlight provides to ground terminals and quantitatively examined its impact on the SNR,communication performance,and beacon detection accuracy of the developed all-free-space ground terminal.Furthermore,we present the results of a daytime demonstration of a 7-km terrestrial free-space optical communication link by employing our ground terminal that was designed based on these analyses.The results verified that 2.5-Gbps data transmission up to 7 km is feasible,even in expected daytime satellite tracking scenarios with high background noise,by the developed system with spectral and spatial filtering to achieve an acceptable SNR.The background noise results of our research are anticipated to further the research on quantum communication networks,light detection and ranging(LiDAR),and green energy technologies.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61575027 and 61471051)
文摘Studying orbital angular momentum（OAM） spectra is important for analyzing crosstalk in free-space optical（FSO）communication systems. This work offers a new method of simplifying the expressions for the OAM spectra of Laguerre-Gaussian（LG） beams under both weak/medium and strong atmospheric turbulences. We propose fixing the radius to the extreme point of the intensity distribution, review the expression for the OAM spectrum under weak/medium turbulence,derive the OAM spectrum expression for an LG beam under strong turbulence, and simplify both of them to concise forms.Then, we investigate the accuracy of the simplified expressions through simulations. We find that the simplified expressions permit accurate calculation of the OAM spectrum for large transmitted OAM numbers under any type of turbulence. Finally,we use the simplified expressions to analytically address the broadening of the OAM spectrum caused by atmospheric turbulence. This work should contribute to the concise theoretical derivation of analytical expressions for OAM channel matrices for FSO-OAM communications and the analytical study of the laws governing OAM spectra.
基金This research was funded by the National Natural Science Foundation of China under Grants 62271202,62027802,and 61831008the Key Research and Development Program of Zhejiang Province under Grant 2023C01003in part by the Open Foundation of State Key Laboratory of Integrated Services Networks Xidian University under Grant ISN23-01.
文摘We analyzed the performance of a freespace optical(FSO)system in this study,considering the combined effects of atmospheric turbulence,fog absorption,and pointing errors.The impacts of atmospheric turbulence and foggy absorption were modeled using the Fisher-Snedecor F distribution and the Gamma distribution,respectively.Next,we derived the probability density function(PDF)and cumulative probability density function of the optical system under these combined effects.Based on these statistical findings,closed-form expressions for various system metrics,such as outage probability,average bit error rate(BER),and ergodic capacity,were derived.Furthermore,we used a deep neural network(DNN)to predict the ergodic capacity of the system,achieving reduced running time and improved accuracy.Finally,the accuracy of the prediction results was validated by comparing them with the analytical results.
文摘This paper explores the ergodic channel capacity of multiple-input single-output(MISO)free-space optical(FSO)communication systems,assisted by(optical)re-configurable intelligent surfaces[(O)RIS],made of concave reflectors.On the one hand,RIS technology mitigates dead zones in communication systems.Additionally,it increases the data rate and communication range,enhances the communication channel by making it intelligent,and improves the system’s capacity.Finally,the RIS technology improves the spectrum and energy efficiencies of the considered systems.On the other hand,transmitting diversity mitigates deep fade and helps to achieve beamforming to regulate the beam sent in a specific direction.Finally,multiple light sources help to send different versions of the same information at other time slots.Furthermore,compared to flat reflectors,concave mirrors provide economic advantages enabled by their natural shape,which helps converge the impinging light beams into the same focal point.In this paper,we harness the full potential of ORIS and MISO technologies in an FSO system by exploiting the hollow of concave reflectors to focus the reflected beams on a single user.We derive an approximated closed-form expression,provide results of the proposed ORIS-aided FSO systems’ergodic channel capacity,and discuss the suitable type of concave reflector.These results show that all types of concave mirrors provide similar results except when the thickness of the reflector is large enough to impact the reflected light.
