This paper reports, for the first time, observation results of the Coherent Beacon System(CBS) onboard the China SeismoElectromagnetic Satellite-1(CSES-1). We describe the CBS, and the Computerized Ionospheric Tomogra...This paper reports, for the first time, observation results of the Coherent Beacon System(CBS) onboard the China SeismoElectromagnetic Satellite-1(CSES-1). We describe the CBS, and the Computerized Ionospheric Tomography(CIT) algorithm program is validated by numerical experiment. Two examples are shown, for daytime and nighttime respectively. The Equatorial Ionization Anomaly(EIA) can be seen, and the northern crest core is located at ～20°N in the reconstruction image at 07:28 UTC on 20 July 2018(daytime).Disturbances are shown in the reconstruction image at 18:40 UTC on 13 July 2018(nighttime). We find that beacon measurements are more consistent with ionosonde measurements than model results, by comparing Nm F2 at three sites at Lanzhou, Chongqing, and Kunming; consistency with ionosonde measurements validates beacon measurements. Finally, we have studied Vertical Total Electron Content(VTEC) variations from ground to ～500 km(the height of CSES-1 orbit) and ratios of VTEC between beacon measurements and CODE(Center for Orbit Determination in Europe) data. VTEC variation from ground to ～500 km has a range of 7.2–16.5 TECU for the daytime case and a range of 1.1–1.7 TECU for the nighttime case. The Beacon/CODE ratio of VTEC varies with latitude and time. The mean Beacon/CODE ratio is 0.69 for the daytime case and 0.26 for the nighttime case. The fact that the nighttime case yields lower ratios indicates the higher altitude of the ionosphere during nighttime when the ionosphere is assumed to be a thin layer.展开更多
In order to solve the onboard recorder search problem, a new beacon system based on radio direction finding tech- nique, which indicates the orientation of the recorder, is designed. The system consists of phase-locke...In order to solve the onboard recorder search problem, a new beacon system based on radio direction finding tech- nique, which indicates the orientation of the recorder, is designed. The system consists of phase-locked loop （PLL）, micro- processor, global position system （GPS） module, power module and so on. The scene simulation verifies the feasibility and reliability of the system. This beacon system can be applied to the recorder search in many fields, and can effectively reduce the search scope and improve work efficiency.展开更多
Terahertz(THz)and millimeter Wave(mmWave)have been considered as potential frequency bands for 6G cellular systems to meet the need of ultra-high data rates.However,indoor communications could be blocked in THz/mmW ce...Terahertz(THz)and millimeter Wave(mmWave)have been considered as potential frequency bands for 6G cellular systems to meet the need of ultra-high data rates.However,indoor communications could be blocked in THz/mmW cellular systems due to the high free-space propagation loss.Deploying a large number of small base stations indoors has been considered as a promising solution for solving indoor coverage problems.However,base station dense deployment leads to a significant increase in system energy consumption.In this paper,we develop a novel ultra-e˙icient energy-saving mechanism with the aim of reducing energy consumption in 6G distributed indoor base station scenarios.Unlike the existing relevant protocol framework of 3GPP,which operates the cellular system based on constant system signaling messages(including cell ID,cell reselection information,etc.),the proposed mechanism eliminates the need for system messages.The intuition comes from the observation that the probability of having no users within the coverage area of an indoor base station is high,hence continuously sending system messages to guarantee the quality of service is unnecessary in indoor scenarios.Specifically,we design a dedicated beacon signal to detect whether there are users in the coverage area of the base station and switch offthe main communication module when there are no active users for energy saving.The beacon frame structure is carefully designed based on the existing 3GPP specifications with minimal protocol modifications,and the protocol parameters involved are optimized.Simulation results show that the proposed mechanism can reduce the system energy from the order of tens of watts to the order of hundreds of milliwatts.Compared to traditional energy-saving schemes,the proposed mechanism achieves an average energy-saving gain of 58%,with a peak energy-saving gain of 90%.展开更多
From the actual perspective of working principle of localizer beacon subsystem of Instrument Landing System (ILS), consideration of the distance information from localizer antenna to field monitor antenna and wide ape...From the actual perspective of working principle of localizer beacon subsystem of Instrument Landing System (ILS), consideration of the distance information from localizer antenna to field monitor antenna and wide aperture effect of localizer antenna, broke through the limitation of signals synthesized only far-field (FF), established the near-field (NF) model. The three-dimensional mathematical model of localizer beacon was designed, and the signals at both near-field and far-field were analyzed qualitatively. At the environment of Antenna Fault as well as Antenna Distribution Unit (ADU) phase shifter simulation, the characteristics of near-field and far-field were also compared. The simulation results showed that the model met the requirement of theory of localizer beacon, and the gap between two models was so evident, which resulted from the broken geometric symmetry in NF area. The model could provide valuable theoretical basis for performance evaluation and maintenance of the ILS, and meanwhile, provide reference for the further analysis of localizer beacon.展开更多
Nowadays, Global Positioning Systems (GPS) receivers are used for outdoor navigation, which are the part of recent smartphones and tablet devices. However, GPS is not suitable for indoor navigations due to its signal ...Nowadays, Global Positioning Systems (GPS) receivers are used for outdoor navigation, which are the part of recent smartphones and tablet devices. However, GPS is not suitable for indoor navigations due to its signal limitations which are blocked by ceiling and walls. Indoor navigation can be achieved through a mobile phone using a recent technology that utilizes Bluetooth, namely beacons. Beacons are small transmitters, run on Bluetooth Low Energy (BLE) technology, used as a point of reference for mobile devices and they can detect a Bluetooth enabled device once it enters its transmission range. In this paper, we present BeaLib: a beacon assisted indoor navigation technique for smart libraries. The proposed indoor navigation technique can also be used for other applications such as offices, retails, airports, hospitality, and education. For experimentation, beacons are placed in a library and a Bluetooth enabled smartphone is used to install a digital library application (App) which communicates with the beacons. The result shows that when the smartphone comes in the range of a beacon, it shows the information related to the book on the smartphone screen.展开更多
The study projects a flexible and compact wearable pear-shaped Super High Frequency(SHF)antenna that can provide detailed location recognition and tracking applicable to defense beacon technology.This mini aperture wi...The study projects a flexible and compact wearable pear-shaped Super High Frequency(SHF)antenna that can provide detailed location recognition and tracking applicable to defense beacon technology.This mini aperture with electrical dimensions of 0.12λ_(0)×0.22λ_(0)×0.01λ_(0)attains a vast bandwidth over 3.1-34.5 GHz Super High Frequency(SHF)frequency band at S_(11)≤-10 dB,peak gain of 7.14 dBi and proportionately homogeneous radiation pattern.The fractional bandwidth(%BW)acquired is 168%that envelopes diversified frequency spectrum inclusive of X band specifically targeted to all kinds of defense and military operations.The proposed antenna can be worn on a soldier's uniform and hence the Specific Absorption Rate simulation is accomplished.The Peak SAR Value over 1 g of tissue is 1.48 W/kg and for 10 g of tissue is 0.27 W/kg well under the safety standards.The flexibility is proven by analyzing the full electromagnetic simulations for various bending conditions.Time response analysis is attained with its Fidelity Factor and Group Delay.Communication excellence is determined using Link Budget Analysis and it is seen that margin at 100 Mbps is 62 m and at 200 Mbps is 59 m.Prototype is fabricated along with experimental validation.All the results show harmony in shaping the antenna to provide critical situational awareness and data sharing capabilities required in defense beacon technology for location identification.展开更多
车载网络(Vehicular ad hoc networks,VANETs)是一种特殊形式的网络,具有节点高速移动、拓扑频繁的变化的特性,这些特性为消息的传播带来挑战,路由机制是实现消息传递的关键因素;地理位置路由被广泛地应用于VANETS,要求节点周期广播bea...车载网络(Vehicular ad hoc networks,VANETs)是一种特殊形式的网络,具有节点高速移动、拓扑频繁的变化的特性,这些特性为消息的传播带来挑战,路由机制是实现消息传递的关键因素;地理位置路由被广泛地应用于VANETS,要求节点周期广播beacon消息;然而,节点周期地广播beacon消息,降低了路由性能,特别是在城市区域,由于节点密集,每个节点均广播beacon消息,恶化了路由性能;为此,针对城市环境,提出基于beacon控制的路由协议RPBC(Routing protocol with beacon control);在RPBC中,并非每个节点广播beacon消息,而设置有效的机制选择部分节点广播,从而降低了beacon冗余,同时,采用最短路径算法,减少数据传输跳数;仿真结果表明,提出的RBPC在分组投递率、端到端传输时延以及路由开销方面均有较好的性能。展开更多
On the basis of Hartmann Shack sensor imaging analysis, a new method is presented with which the wavefront slope can be obtained when the object is incoherent and extended. This method, which is demonstrated by both ...On the basis of Hartmann Shack sensor imaging analysis, a new method is presented with which the wavefront slope can be obtained when the object is incoherent and extended. This method, which is demonstrated by both theoretical interpreting and computer simulation, explains how to measure the wavefront slope difference between two sub apertures through the determination of image displacements on detector plane. It includes a fast and accurate digital algorithm for detecting wavefront disturbance, which is much suitable for realization in such electrical hardwares as digital signal processors.展开更多
基金supported by the “China Seismo-Electromagnetic Satellite (CSES)” projectthe 13th Five-Year Technology Program (Grant No. 315030409)
文摘This paper reports, for the first time, observation results of the Coherent Beacon System(CBS) onboard the China SeismoElectromagnetic Satellite-1(CSES-1). We describe the CBS, and the Computerized Ionospheric Tomography(CIT) algorithm program is validated by numerical experiment. Two examples are shown, for daytime and nighttime respectively. The Equatorial Ionization Anomaly(EIA) can be seen, and the northern crest core is located at ～20°N in the reconstruction image at 07:28 UTC on 20 July 2018(daytime).Disturbances are shown in the reconstruction image at 18:40 UTC on 13 July 2018(nighttime). We find that beacon measurements are more consistent with ionosonde measurements than model results, by comparing Nm F2 at three sites at Lanzhou, Chongqing, and Kunming; consistency with ionosonde measurements validates beacon measurements. Finally, we have studied Vertical Total Electron Content(VTEC) variations from ground to ～500 km(the height of CSES-1 orbit) and ratios of VTEC between beacon measurements and CODE(Center for Orbit Determination in Europe) data. VTEC variation from ground to ～500 km has a range of 7.2–16.5 TECU for the daytime case and a range of 1.1–1.7 TECU for the nighttime case. The Beacon/CODE ratio of VTEC varies with latitude and time. The mean Beacon/CODE ratio is 0.69 for the daytime case and 0.26 for the nighttime case. The fact that the nighttime case yields lower ratios indicates the higher altitude of the ionosphere during nighttime when the ionosphere is assumed to be a thin layer.
文摘In order to solve the onboard recorder search problem, a new beacon system based on radio direction finding tech- nique, which indicates the orientation of the recorder, is designed. The system consists of phase-locked loop （PLL）, micro- processor, global position system （GPS） module, power module and so on. The scene simulation verifies the feasibility and reliability of the system. This beacon system can be applied to the recorder search in many fields, and can effectively reduce the search scope and improve work efficiency.
基金supported by the National Natural Science Foundation of China under Grant No.62201121the Fundamental Fundamental Research Funds for Central Universities under Grant No.ZYGX2024XJ070。
文摘Terahertz(THz)and millimeter Wave(mmWave)have been considered as potential frequency bands for 6G cellular systems to meet the need of ultra-high data rates.However,indoor communications could be blocked in THz/mmW cellular systems due to the high free-space propagation loss.Deploying a large number of small base stations indoors has been considered as a promising solution for solving indoor coverage problems.However,base station dense deployment leads to a significant increase in system energy consumption.In this paper,we develop a novel ultra-e˙icient energy-saving mechanism with the aim of reducing energy consumption in 6G distributed indoor base station scenarios.Unlike the existing relevant protocol framework of 3GPP,which operates the cellular system based on constant system signaling messages(including cell ID,cell reselection information,etc.),the proposed mechanism eliminates the need for system messages.The intuition comes from the observation that the probability of having no users within the coverage area of an indoor base station is high,hence continuously sending system messages to guarantee the quality of service is unnecessary in indoor scenarios.Specifically,we design a dedicated beacon signal to detect whether there are users in the coverage area of the base station and switch offthe main communication module when there are no active users for energy saving.The beacon frame structure is carefully designed based on the existing 3GPP specifications with minimal protocol modifications,and the protocol parameters involved are optimized.Simulation results show that the proposed mechanism can reduce the system energy from the order of tens of watts to the order of hundreds of milliwatts.Compared to traditional energy-saving schemes,the proposed mechanism achieves an average energy-saving gain of 58%,with a peak energy-saving gain of 90%.
文摘From the actual perspective of working principle of localizer beacon subsystem of Instrument Landing System (ILS), consideration of the distance information from localizer antenna to field monitor antenna and wide aperture effect of localizer antenna, broke through the limitation of signals synthesized only far-field (FF), established the near-field (NF) model. The three-dimensional mathematical model of localizer beacon was designed, and the signals at both near-field and far-field were analyzed qualitatively. At the environment of Antenna Fault as well as Antenna Distribution Unit (ADU) phase shifter simulation, the characteristics of near-field and far-field were also compared. The simulation results showed that the model met the requirement of theory of localizer beacon, and the gap between two models was so evident, which resulted from the broken geometric symmetry in NF area. The model could provide valuable theoretical basis for performance evaluation and maintenance of the ILS, and meanwhile, provide reference for the further analysis of localizer beacon.
文摘Nowadays, Global Positioning Systems (GPS) receivers are used for outdoor navigation, which are the part of recent smartphones and tablet devices. However, GPS is not suitable for indoor navigations due to its signal limitations which are blocked by ceiling and walls. Indoor navigation can be achieved through a mobile phone using a recent technology that utilizes Bluetooth, namely beacons. Beacons are small transmitters, run on Bluetooth Low Energy (BLE) technology, used as a point of reference for mobile devices and they can detect a Bluetooth enabled device once it enters its transmission range. In this paper, we present BeaLib: a beacon assisted indoor navigation technique for smart libraries. The proposed indoor navigation technique can also be used for other applications such as offices, retails, airports, hospitality, and education. For experimentation, beacons are placed in a library and a Bluetooth enabled smartphone is used to install a digital library application (App) which communicates with the beacons. The result shows that when the smartphone comes in the range of a beacon, it shows the information related to the book on the smartphone screen.
基金the Defense Institute of Advanced Technology,Pune(DIAT,Pune)IIT Delhi。
文摘The study projects a flexible and compact wearable pear-shaped Super High Frequency(SHF)antenna that can provide detailed location recognition and tracking applicable to defense beacon technology.This mini aperture with electrical dimensions of 0.12λ_(0)×0.22λ_(0)×0.01λ_(0)attains a vast bandwidth over 3.1-34.5 GHz Super High Frequency(SHF)frequency band at S_(11)≤-10 dB,peak gain of 7.14 dBi and proportionately homogeneous radiation pattern.The fractional bandwidth(%BW)acquired is 168%that envelopes diversified frequency spectrum inclusive of X band specifically targeted to all kinds of defense and military operations.The proposed antenna can be worn on a soldier's uniform and hence the Specific Absorption Rate simulation is accomplished.The Peak SAR Value over 1 g of tissue is 1.48 W/kg and for 10 g of tissue is 0.27 W/kg well under the safety standards.The flexibility is proven by analyzing the full electromagnetic simulations for various bending conditions.Time response analysis is attained with its Fidelity Factor and Group Delay.Communication excellence is determined using Link Budget Analysis and it is seen that margin at 100 Mbps is 62 m and at 200 Mbps is 59 m.Prototype is fabricated along with experimental validation.All the results show harmony in shaping the antenna to provide critical situational awareness and data sharing capabilities required in defense beacon technology for location identification.
文摘车载网络(Vehicular ad hoc networks,VANETs)是一种特殊形式的网络,具有节点高速移动、拓扑频繁的变化的特性,这些特性为消息的传播带来挑战,路由机制是实现消息传递的关键因素;地理位置路由被广泛地应用于VANETS,要求节点周期广播beacon消息;然而,节点周期地广播beacon消息,降低了路由性能,特别是在城市区域,由于节点密集,每个节点均广播beacon消息,恶化了路由性能;为此,针对城市环境,提出基于beacon控制的路由协议RPBC(Routing protocol with beacon control);在RPBC中,并非每个节点广播beacon消息,而设置有效的机制选择部分节点广播,从而降低了beacon冗余,同时,采用最短路径算法,减少数据传输跳数;仿真结果表明,提出的RBPC在分组投递率、端到端传输时延以及路由开销方面均有较好的性能。
文摘On the basis of Hartmann Shack sensor imaging analysis, a new method is presented with which the wavefront slope can be obtained when the object is incoherent and extended. This method, which is demonstrated by both theoretical interpreting and computer simulation, explains how to measure the wavefront slope difference between two sub apertures through the determination of image displacements on detector plane. It includes a fast and accurate digital algorithm for detecting wavefront disturbance, which is much suitable for realization in such electrical hardwares as digital signal processors.
