On 2 December 2024,the Chinese Association for International Understanding(CAFIU),Thai-China Culture and Economy Association(TCCEA)and the Chinese Embassy in Thailand jointly hosted the Civilisation Lecture Series eve...On 2 December 2024,the Chinese Association for International Understanding(CAFIU),Thai-China Culture and Economy Association(TCCEA)and the Chinese Embassy in Thailand jointly hosted the Civilisation Lecture Series event themed Enhancing Exchanges and Integration among Civilisations and Writing A New Chapter of China-Thailand Brotherhood Relations.CAFIU President Ji Bingxuan,who was on a visit in Thailand,attended the event and delivered a keynote speech.展开更多
With the further reduction in cost and the increase in bandwidth, as well as the increase in internet applications, satellite communications are gradually shifting from a complementary role to becoming a fully integra...With the further reduction in cost and the increase in bandwidth, as well as the increase in internet applications, satellite communications are gradually shifting from a complementary role to becoming a fully integrated component of terrestrial communications networks. This paper firstly introduces the development of satellite communications, mobile communications and the global space-terrestrial integrated network. We then propose the functional architecture and network architecture for the integration of satellite communications and terrestrial mobile communications based on 5 G core networks. Finally, in order to support the network of the future, four key technologies are presented, a space-terrestrial integrated air interface design, a multi-band space-terrestrial integrated transmission waveform design, space-terrestrial integrated switching and routing technology, along with spectrum sharing and interference coordination technology, all necessary for the development of space-terrestrial integrated networks.展开更多
With the rapid growth of the low-altitude economy,the demand for typical low-altitude ap-plications has accelerated the advancement of inte-grated sensing and communications(ISAC)networks.This paper begins by analyzin...With the rapid growth of the low-altitude economy,the demand for typical low-altitude ap-plications has accelerated the advancement of inte-grated sensing and communications(ISAC)networks.This paper begins by analyzing representative ap-plication scenarios to clarify the core requirements of the low-altitude economy for modern ISAC net-works.By investigating the distinctive characteris-tics of ISAC networks in low-altitude environments,it presents a comprehensive analysis of key challenges and identifies four major issues:challenges in pre-cise target detection,interference management,in-consistent sensing and communication coverage,and the complexity of air-ground coordination and han-dover.Based on fundamental theories and principles,the paper proposes corresponding solutions,encom-passing advanced technologies for precise target de-tection and recognition,high-reliability networked de-tection,robust interference management,and seamless air-ground collaboration.These solutions aim to es-tablish a solid foundation for the future development of intelligent low-altitude networks and ensure effec-tive support for emerging applications.展开更多
With the widespread application of com-munication technology in the non-terrestrial network(NTN),the issue of the insecure communication due to the inherent openness of the NTN is increasingly being recognized.Consequ...With the widespread application of com-munication technology in the non-terrestrial network(NTN),the issue of the insecure communication due to the inherent openness of the NTN is increasingly being recognized.Consequently,safeguarding com-munication information in the NTN has emerged as a critical challenge.To address this issue,we pro-pose a beamforming and horizontal trajectory joint op-timization method for unmanned aerial vehicle(UAV)covert communications in the NTN.First,we formu-late an optimization problem that considers constraints such as the transmitting power and the distance.More-over,we employ the integrated communication and jamming(ICAJ)signal as Alice’s transmitting signal,further protecting the content of communication in-formation.Next,we construct two subproblems,and we propose an alternate optimization(AO)algorithm based on quadratic transform and penalty term method to solve the proposed two subproblems.Simulation re-sults demonstrate that the proposed method is effective and has better performance than benchmarks.展开更多
Space/air communications have been envisioned as an essential part of the next-generation mobile communication networks for providing highquality global connectivity. However, the inherent broadcasting nature of wirel...Space/air communications have been envisioned as an essential part of the next-generation mobile communication networks for providing highquality global connectivity. However, the inherent broadcasting nature of wireless propagation environment and the broad coverage pose severe threats to the protection of private data. Emerging covert communications provides a promising solution to achieve robust communication security. Aiming at facilitating the practical implementation of covert communications in space/air networks, we present a tutorial overview of its potentials, scenarios, and key technologies. Specifically, first, the commonly used covertness constraint model, covert performance metrics, and potential application scenarios are briefly introduced. Then, several efficient methods that introduce uncertainty into the covert system are thoroughly summarized, followed by several critical enabling technologies, including joint resource allocation and deployment/trajectory design, multi-antenna and beamforming techniques, reconfigurable intelligent surface(RIS), and artificial intelligence algorithms. Finally, we highlight some open issues for future investigation.展开更多
Satellite communications, pivotal for global connectivity, are increasingly converging with cutting-edge mobile networks, notably 5G, B5G, and 6G. This amalgamation heralds the promise of universal, high-velocity comm...Satellite communications, pivotal for global connectivity, are increasingly converging with cutting-edge mobile networks, notably 5G, B5G, and 6G. This amalgamation heralds the promise of universal, high-velocity communication, yet it is not without its challenges. Paramount concerns encompass spectrum allocation, the harmonization of network architectures, and inherent latency issues in satellite transmissions. Potential mitigations, such as dynamic spectrum sharing and the deployment of edge computing, are explored as viable solutions. Looking ahead, the advent of quantum communications within satellite frameworks and the integration of AI spotlight promising research trajectories. These advancements aim to foster a seamless and synergistic coexistence between satellite communications and next-gen mobile networks.展开更多
A 3D fan-out packaging method for the integration of 5G communication RF microsystem and antenna is studied.First of all,through the double-sided wiring technology on the glass wafer,the fabrication of 5G antenna arra...A 3D fan-out packaging method for the integration of 5G communication RF microsystem and antenna is studied.First of all,through the double-sided wiring technology on the glass wafer,the fabrication of 5G antenna array is realized.Then the low power devices such as through silicon via(TSV)transfer chips,filters and antenna tuners are flip-welded on the glass wafer,and the glass wafer is reformed into a wafer permanently bonded with glass and resin by the injection molding process with resin material.Finally,the thinning resin surface leaks out of the TSV transfer chip,the rewiring is carried out on the resin surface,and then the power amplifier,low-noise amplifier,power management and other devices are flip-welded on the resin wafer surface.A ball grid array(BGA)is implanted to form the final package.The loss of the RF transmission line is measured by using the RF millimeter wave probe table.The results show that the RF transmission loss from the chip end to the antenna end in the fan-out package is very small,and it is only 0.26 dB/mm when working in 60 GHz.A slot coupling antenna is designed on the glass wafer.The antenna can operate at 60 GHz and the maximum gain can reach 6 dB within the working bandwidth.This demonstration successfully provides a feasible solution for the 3D fan-out integration of RF microsystem and antenna in 5G communications.展开更多
Frequency synthesizer is an important part of optical and wireless communication system. Low power comsumption prescaler is one of the most critical unit of frequency synthesizer. For the frequency divider, it must be...Frequency synthesizer is an important part of optical and wireless communication system. Low power comsumption prescaler is one of the most critical unit of frequency synthesizer. For the frequency divider, it must be programmable for channel selection in multi-channel communication systems. A dual-modulus prescaler (DMP) is needed to provide variable division ratios. DMP is considered as a critical power dissipative block since it always operates at full speed. This paper introduces a high speed and low power complementary metal oxide semiconductor (CMOS) 15/16 DMP based on true single-phase-clock (TSPC) and transmission gates (TGs) cell. A conventional TSPC is optimized in terms of devices size, and it is resimulated. The TSPC is used in the synchronous and asynchronous counter. TGs are used in the control logic. The DMP circuit is implemented in 0.18 μm CMOS process. The simulation results are provided. The results show wide operating frequency range from 7.143 MHz to 4.76 GHz and it comsumes 3.625 mW under 1.8 V power supply voltage at 4.76 GHz.展开更多
The study of the history of exchanges,communication and integration of the Chinese nation belongs to the specialized research category of history(thematic history).It has a close inheritance relationship with traditio...The study of the history of exchanges,communication and integration of the Chinese nation belongs to the specialized research category of history(thematic history).It has a close inheritance relationship with traditional ethnic history,and border history research,and has obvious development.The study of the history of"Exchanges,Communication and Integration"is based on historical studies and adopts interdisciplinary methods.Through four thematic fields of politics,economy,society and culture,it excavates,organizes,and studies the basic historical facts of exchanges,communication and integration within and between the Chinese nation.It reveals that the various ethnic groups in China reach a consensus politically,integrate with each other culturally,connect closely to each other emotionally,and ultimately form a pattern of unity in diversity.It responds to the requirements of the new era for historical research,with the main focus on fostering a strong sense of community for the Chinese nation,adhering to the correct historical view of the Chinese nation,adhering to the theory of unity in diversity pattern of the Chinese nation,and promoting the Chinese nation to become a community with a higher degree of identity and stronger cohesion.展开更多
In this paper,an integrated substrate gap waveguide(ISGW)filtering antenna is proposed at millimeter wave band,whose surface wave and spurious modes are simultaneously suppressed.A secondorder filtering response is ob...In this paper,an integrated substrate gap waveguide(ISGW)filtering antenna is proposed at millimeter wave band,whose surface wave and spurious modes are simultaneously suppressed.A secondorder filtering response is obtained through a coupling feeding scheme using one uniform impedance resonator(UIR)and two stepped-impedance resonators(SIRs).To increase the stopband width of the antenna,the spurious modes are suppressed by selecting the appropriate sizes of the ISGW unit cell.Furthermore,the ISGW is implemented to improve the radiation performance of the antenna by alleviating the propagation of surface wave.And an equivalent circuit is investigated to reveal the working principle of ISGW.To demonstrate this methodology,an ISGW filtering antenna operating at a center frequency of 25 GHz is designed,fabricated,and measured.The results show that the antenna achieves a stopband width of 1.6f0(center frequency),an out-of-band suppression level of 21 dB,and a peak realized gain of 8.5 dBi.展开更多
This paper summarizes the requirements for modem maritime wireless communication networks in the marine environments including the sea- to-sea and sea-to-shore communication scenarios. The existing maritime wireless c...This paper summarizes the requirements for modem maritime wireless communication networks in the marine environments including the sea- to-sea and sea-to-shore communication scenarios. The existing maritime wireless communication sys- tems are presented and the development of the state-of-the-art maritime communication systems is surveyed. Furthermore, a hierarchical and integrated maritime network architecture is proposed to satisfy the increasing various classes of services which demand different Quality of Service （QoS）. Finally, the open issues for further development of maritime communications are identified.展开更多
An electro-absorption(EA)modulator is one of key components for optical fiber communications due to the high speed,small size,low voltage and integration ability with other semiconductor devices.A 40 Gb/s InGaAsP/InP ...An electro-absorption(EA)modulator is one of key components for optical fiber communications due to the high speed,small size,low voltage and integration ability with other semiconductor devices.A 40 Gb/s InGaAsP/InP multiplequantum-well(MQW)EA modulator monolithically integrated with a semiconductor optical amplifier(SOA)was fabricated for digital communications.The modulator capacitance was reduced to obtain 40 GHz bandwidth,and the SOA section helped reduce the insertion loss from 18 dB to 3 dB.InGaAlAs/InP MQW EA modulators have also been fabricated and characterized for analog optical fiber communications.A low driving voltage of 2.7 V and high spurious free dynamic range of 107 dB·Hz2/3 were estimated by static and dynamic measurements.展开更多
The Joy Luck Club written by Chinese American writer Amy Tan depicts the conflicts and reconciliation between the Chinese-born mothers and American-born daughters, reflecting the clashes and fusions of two different c...The Joy Luck Club written by Chinese American writer Amy Tan depicts the conflicts and reconciliation between the Chinese-born mothers and American-born daughters, reflecting the clashes and fusions of two different cultures. This paper sets out from the intercultural perspective to probe into the cultural factors which contribute to the failure in communication, and strives to get inspirations from the four pair of mothers and daughters to eliminate cross-culture communication barriers.展开更多
Covert unmanned aerial vehicle(UAV)communication has garnered considerable attention in wireless systems for realizing the sustainable low-altitude economy(LAE).This paper investigates the system policy,trajectory des...Covert unmanned aerial vehicle(UAV)communication has garnered considerable attention in wireless systems for realizing the sustainable low-altitude economy(LAE).This paper investigates the system policy,trajectory design,and resource allocation for energy-efficient aerial networked systems with the aid of an integrated sensing and communications(ISAC)framework,in which multiple UAVs are employed to simultaneously conduct cooperative sensing and covert downlink transmissions to multiple ground users(GUs)in the presence of a mobile warden(Willie).Specifically,to improve the communication covertness,UAVs are strategically switched between jamming(JUAV)and information(IUAV)modes.Additionally,to cope with the mobility of Willie,an unscented Kalman filtering(UKF)-based method is employed to track and predict Willie’s location relying on the delay and Doppler measurements extracted from the ISAC echoes.Capitalizing on the predicted Willie’s location,a real-time energy efficiency(EE)maximization problem is formulated by jointly optimizing the JUAV selection strategy,IUAV-GU scheduling,communication/jamming power allocation,and UAV trajectories design.The formulation takes into account the communication covertness requirement and the maximum transmit power budget,leading to a mixed-integer non-convex fractional programming.To tackle this challenge,the alternating optimization(AO)approach is adopted,which decomposes the original problem into a series of sub-problems,allowing us to obtain an efficient sub-optimal solution.Simulation results demonstrate that the proposed scheme is capable of tracking Willie accurately and offering excellent system EE performance compared to various benchmark schemes adopting existing designs.展开更多
Quantum communications aim to share encryption keys between the transmitters and receivers governed by the laws of quantum mechanics.Integrated quantum photonics offers significant advantages of dense integration,high...Quantum communications aim to share encryption keys between the transmitters and receivers governed by the laws of quantum mechanics.Integrated quantum photonics offers significant advantages of dense integration,high stability and scalability,which enables a vital platform for the implementation of quantum information processing and quantum communications.This article reviews recent experimental progress and advances in the development of integrated quantum photonic devices and systems for quantum communications and quantum networks.展开更多
Ningxia is an ethnic gathering area boasting abundant tourism and cultural resources.Developing the cause of tourism and culture is an important way to encourage all ethnic groups to respect differences,embrace divers...Ningxia is an ethnic gathering area boasting abundant tourism and cultural resources.Developing the cause of tourism and culture is an important way to encourage all ethnic groups to respect differences,embrace diversity,and demonstrate their interactions,exchanges,and integration in tourism activities.As an important preserve of the distinctive cultures of the Chinese nation and a prominent world tourist destination,Ningxia should strive to foster and consolidate the sense of a community with a shared future for the Chinese nation in developing its tourism and culture under the new historical conditions.It is imperative to advance the prosperity and development of tourism and culture in boosting ethnic interactions,exchanges,and integration through the formulation of tourism and cultural policies and plans,as well as the development and design of tourism and cultural projects.展开更多
A solar-blind multi-quantum well(MQW)structure wafer based on AlGaN materials is epitaxial growth by metal-organic chemical vapor deposition(MOCVD).The monolithically integrated photonic chips including light-emitting...A solar-blind multi-quantum well(MQW)structure wafer based on AlGaN materials is epitaxial growth by metal-organic chemical vapor deposition(MOCVD).The monolithically integrated photonic chips including light-emitting diodes(LEDs),waveguides,and photodetec-tors(PDs)are presented.The results of the finite-difference time-domain(FDTD)simulation confirm the strong light constraint of the wave-guide designed with the triangular structure in the optical coupling region.Furthermore,in virtue of predominant ultraviolet transverse mag-netic(TM)modes,the solar blind optical signal is more conducive to lateral transmission along the waveguide inside the integrated chip.The integrated PDs demonstrate sufficient photosensitivity to the optical signal from the integrated LEDs.When the LEDs are operated at 100 mA current,the photo-to-dark current ratio(PDCR)of the integrated PD is about seven orders of magnitude.The responsivity,specific detectivity,and external quantum efficiency of the integrated self-driven PD are 74.89 A/W,4.22×1013 Jones,and 3.38×104%,respectively.The stable on-chip optical information transmission capability of the monolithically integrated photonic chips confirms the great potential for application in large-scale on-chip optical communication in the future.展开更多
The research on scheduling and heat integration of batch process plays an important role in reducing energy consumption,improving production efficiency and enhancing the competitiveness of industries.The complexity an...The research on scheduling and heat integration of batch process plays an important role in reducing energy consumption,improving production efficiency and enhancing the competitiveness of industries.The complexity and difficulty of the model solving are increased due to the comprehensive consideration of both scheduling and heat integration.In this paper,the mixed integer nonlinear programming(MINLP) mathematical model of multi-product plant heat integration optimization with the goal of energy-saving annual profit(EAP) is established.The simultaneous optimization and sequential optimization are carried out respectively by bi-level programming(BP) based on the genetic algorithm(GA),and the calculation results are compared.EAP better captures the trade-off relationship between scheduling schemes,energy-saving profits,and equipment costs.The bi-level programming approach based on GA categorizes variables into integer and real types,enabling structural optimization and parameter optimization of the heat exchanger network.This,in turn,enhances solution efficiency and overcomes the limitations of conventional optimization algorithms in terms of solution speed and quality.Two examples show that the EAP of indirect heat integration considering the storage tank are 21% and 2% higher than that of the direct heat integration,and EAP of the simultaneous optimization are26% and 6% higher than that of the sequential optimization.The example demonstrates that the model and algorithm are applicable to batch multi-product plants,such as those in the chemical,pharmaceutical,and food industries,and possess strong practicality and innovation.展开更多
Integrated sensing and communication(ISAC)is an appealing approach to address spectrum congestion and beamforming is an effective method to realize ISAC.In this paper,we investigate the beamforming design problem for ...Integrated sensing and communication(ISAC)is an appealing approach to address spectrum congestion and beamforming is an effective method to realize ISAC.In this paper,we investigate the beamforming design problem for multiple-input multipleoutput(MIMO)ISAC systems and propose to maximize the radar beampattern gain of the target direction while ensuring the signal-to-interference-plus-noise ratio(SINR)constraints of communication users.Particularly,we discuss two cases of ISAC transmit beamforming,i.e.,Case-Ⅰand Case-Ⅱ,which do not have and do have the dedicated probing signal,respectively.For these two cases of transmit beamforming design problems,we start from the single-user scenario and provide the closed-form solutions for MIMO ISAC beamforming vectors.Then,we consider the multiuser scenario and utilize the semidefinite relaxation technique to convert the beamforming design problems into convex semidefinite programming problems.Furthermore,we investigate the impact of the channel correlation between radar and communication on the performance gain of MIMO ISAC systems and characterize the performance tradeoff.Numerical results validate that the dedicated probing signal is unnecessary in the single-user scenario,whereas it has a slight improvement in target detection performance at low SINR thresholds in the multi-user scenario.It is also shown that the stronger the correlation between radar and communication channels,the greater the performance gain of the system.展开更多
The rapid expansion of the low-altitude economy is driving strong demand for highly accurate and reliable positioning technologies to support diverse aerial operations.This review examines core positioning methodologi...The rapid expansion of the low-altitude economy is driving strong demand for highly accurate and reliable positioning technologies to support diverse aerial operations.This review examines core positioning methodologies within the low-altitude intelligent network(LAIN)framework,beginning with an analysis of positioning requirements and performance metrics for low-altitude flight scenarios.It systematically assesses the principles,strengths,and limitations of mainstream positioning systems,including Global Navigation Satellite Systems(GNSS),terrestrial wireless positioning,and autonomous navigation,and it surveys prevalent integrated and cooperative positioning schemes.Our analysis demonstrates that standalone positioning technologies are inadequate in complex low-altitude settings,underscoring the pivotal role of multi-source fusion and unmanned aerial vehicle(UAV)swarm cooperative positioning as future trends.To address infrastructure gaps and high deployment costs in current LAIN systems,we propose a“space−air−ground”integrated and cooperative positioning architecture centered on GNSS and the 5th generation mobile communication technology(5G).The ground layer integrates 5G and GNSS for wide-area enhanced positioning.The aerial layer uses 5G aircraft-to-everything(A2X)and sidelink(SL)communications to build self-organizing networks for cooperative UAV localization.The space layer leverages low Earth orbit(LEO)satellites to overcome coverage limitations in communication and positioning.This hierarchical architecture reduces deployment costs through infrastructure reuse and enables deep integration of communication and navigation capabilities.By supporting collaborative enhancement across all three domains,the framework improves positioning robustness and delivers cost-effective,ubiquitous,and highly reliable positioning services.Finally,we outline promising research directions.This review aims to provide a systematic reference and a novel architectural perspective for the ongoing development of LAIN.展开更多
文摘On 2 December 2024,the Chinese Association for International Understanding(CAFIU),Thai-China Culture and Economy Association(TCCEA)and the Chinese Embassy in Thailand jointly hosted the Civilisation Lecture Series event themed Enhancing Exchanges and Integration among Civilisations and Writing A New Chapter of China-Thailand Brotherhood Relations.CAFIU President Ji Bingxuan,who was on a visit in Thailand,attended the event and delivered a keynote speech.
文摘With the further reduction in cost and the increase in bandwidth, as well as the increase in internet applications, satellite communications are gradually shifting from a complementary role to becoming a fully integrated component of terrestrial communications networks. This paper firstly introduces the development of satellite communications, mobile communications and the global space-terrestrial integrated network. We then propose the functional architecture and network architecture for the integration of satellite communications and terrestrial mobile communications based on 5 G core networks. Finally, in order to support the network of the future, four key technologies are presented, a space-terrestrial integrated air interface design, a multi-band space-terrestrial integrated transmission waveform design, space-terrestrial integrated switching and routing technology, along with spectrum sharing and interference coordination technology, all necessary for the development of space-terrestrial integrated networks.
基金supported by National Science and Technology Major Project of China(Project Number:2024ZD1300100)Fundamental Research Funds for the central universities(2024RC02)+1 种基金National Natural Science Foundation of China(62401077,62321001)Beijing Municipal Natural Science Foundation(L232003)。
文摘With the rapid growth of the low-altitude economy,the demand for typical low-altitude ap-plications has accelerated the advancement of inte-grated sensing and communications(ISAC)networks.This paper begins by analyzing representative ap-plication scenarios to clarify the core requirements of the low-altitude economy for modern ISAC net-works.By investigating the distinctive characteris-tics of ISAC networks in low-altitude environments,it presents a comprehensive analysis of key challenges and identifies four major issues:challenges in pre-cise target detection,interference management,in-consistent sensing and communication coverage,and the complexity of air-ground coordination and han-dover.Based on fundamental theories and principles,the paper proposes corresponding solutions,encom-passing advanced technologies for precise target de-tection and recognition,high-reliability networked de-tection,robust interference management,and seamless air-ground collaboration.These solutions aim to es-tablish a solid foundation for the future development of intelligent low-altitude networks and ensure effec-tive support for emerging applications.
基金supported in part by the National Natural Science Foundation of China under Grant U2441250 and 62231027in part by Natural Science Basic Research Programof Shaanxi under Grant 2024JC-JCQN-63+2 种基金in part by InnovationCapability Support Program of Shaanxi under Grant2024RS-CXTD-01in part by New Technology Research University Cooperation Project under Grant SKX242010031in part by the FundamentalResearch Funds for the Central Universities and theInnovation Fund of Xidian University under GrantYJSJ25007.
文摘With the widespread application of com-munication technology in the non-terrestrial network(NTN),the issue of the insecure communication due to the inherent openness of the NTN is increasingly being recognized.Consequently,safeguarding com-munication information in the NTN has emerged as a critical challenge.To address this issue,we pro-pose a beamforming and horizontal trajectory joint op-timization method for unmanned aerial vehicle(UAV)covert communications in the NTN.First,we formu-late an optimization problem that considers constraints such as the transmitting power and the distance.More-over,we employ the integrated communication and jamming(ICAJ)signal as Alice’s transmitting signal,further protecting the content of communication in-formation.Next,we construct two subproblems,and we propose an alternate optimization(AO)algorithm based on quadratic transform and penalty term method to solve the proposed two subproblems.Simulation re-sults demonstrate that the proposed method is effective and has better performance than benchmarks.
基金supported in part by the National Natural Science Foundation of China(NSFC)under grant numbers U22A2007 and 62171010the Beijing Natural Science Foundation under grant number L212003.
文摘Space/air communications have been envisioned as an essential part of the next-generation mobile communication networks for providing highquality global connectivity. However, the inherent broadcasting nature of wireless propagation environment and the broad coverage pose severe threats to the protection of private data. Emerging covert communications provides a promising solution to achieve robust communication security. Aiming at facilitating the practical implementation of covert communications in space/air networks, we present a tutorial overview of its potentials, scenarios, and key technologies. Specifically, first, the commonly used covertness constraint model, covert performance metrics, and potential application scenarios are briefly introduced. Then, several efficient methods that introduce uncertainty into the covert system are thoroughly summarized, followed by several critical enabling technologies, including joint resource allocation and deployment/trajectory design, multi-antenna and beamforming techniques, reconfigurable intelligent surface(RIS), and artificial intelligence algorithms. Finally, we highlight some open issues for future investigation.
文摘Satellite communications, pivotal for global connectivity, are increasingly converging with cutting-edge mobile networks, notably 5G, B5G, and 6G. This amalgamation heralds the promise of universal, high-velocity communication, yet it is not without its challenges. Paramount concerns encompass spectrum allocation, the harmonization of network architectures, and inherent latency issues in satellite transmissions. Potential mitigations, such as dynamic spectrum sharing and the deployment of edge computing, are explored as viable solutions. Looking ahead, the advent of quantum communications within satellite frameworks and the integration of AI spotlight promising research trajectories. These advancements aim to foster a seamless and synergistic coexistence between satellite communications and next-gen mobile networks.
文摘A 3D fan-out packaging method for the integration of 5G communication RF microsystem and antenna is studied.First of all,through the double-sided wiring technology on the glass wafer,the fabrication of 5G antenna array is realized.Then the low power devices such as through silicon via(TSV)transfer chips,filters and antenna tuners are flip-welded on the glass wafer,and the glass wafer is reformed into a wafer permanently bonded with glass and resin by the injection molding process with resin material.Finally,the thinning resin surface leaks out of the TSV transfer chip,the rewiring is carried out on the resin surface,and then the power amplifier,low-noise amplifier,power management and other devices are flip-welded on the resin wafer surface.A ball grid array(BGA)is implanted to form the final package.The loss of the RF transmission line is measured by using the RF millimeter wave probe table.The results show that the RF transmission loss from the chip end to the antenna end in the fan-out package is very small,and it is only 0.26 dB/mm when working in 60 GHz.A slot coupling antenna is designed on the glass wafer.The antenna can operate at 60 GHz and the maximum gain can reach 6 dB within the working bandwidth.This demonstration successfully provides a feasible solution for the 3D fan-out integration of RF microsystem and antenna in 5G communications.
文摘Frequency synthesizer is an important part of optical and wireless communication system. Low power comsumption prescaler is one of the most critical unit of frequency synthesizer. For the frequency divider, it must be programmable for channel selection in multi-channel communication systems. A dual-modulus prescaler (DMP) is needed to provide variable division ratios. DMP is considered as a critical power dissipative block since it always operates at full speed. This paper introduces a high speed and low power complementary metal oxide semiconductor (CMOS) 15/16 DMP based on true single-phase-clock (TSPC) and transmission gates (TGs) cell. A conventional TSPC is optimized in terms of devices size, and it is resimulated. The TSPC is used in the synchronous and asynchronous counter. TGs are used in the control logic. The DMP circuit is implemented in 0.18 μm CMOS process. The simulation results are provided. The results show wide operating frequency range from 7.143 MHz to 4.76 GHz and it comsumes 3.625 mW under 1.8 V power supply voltage at 4.76 GHz.
文摘The study of the history of exchanges,communication and integration of the Chinese nation belongs to the specialized research category of history(thematic history).It has a close inheritance relationship with traditional ethnic history,and border history research,and has obvious development.The study of the history of"Exchanges,Communication and Integration"is based on historical studies and adopts interdisciplinary methods.Through four thematic fields of politics,economy,society and culture,it excavates,organizes,and studies the basic historical facts of exchanges,communication and integration within and between the Chinese nation.It reveals that the various ethnic groups in China reach a consensus politically,integrate with each other culturally,connect closely to each other emotionally,and ultimately form a pattern of unity in diversity.It responds to the requirements of the new era for historical research,with the main focus on fostering a strong sense of community for the Chinese nation,adhering to the correct historical view of the Chinese nation,adhering to the theory of unity in diversity pattern of the Chinese nation,and promoting the Chinese nation to become a community with a higher degree of identity and stronger cohesion.
基金This work was supported by the National Key research and development program of China(No.2021YFB 2900401)the national natural science foundation of China(No.62361057,No.61861046)+1 种基金the key natural science foundation of Shenzhen(No.JCYJ20220818102209020)the key research and development program of Shenzhen(No.ZDSYS20210623091807023).
文摘In this paper,an integrated substrate gap waveguide(ISGW)filtering antenna is proposed at millimeter wave band,whose surface wave and spurious modes are simultaneously suppressed.A secondorder filtering response is obtained through a coupling feeding scheme using one uniform impedance resonator(UIR)and two stepped-impedance resonators(SIRs).To increase the stopband width of the antenna,the spurious modes are suppressed by selecting the appropriate sizes of the ISGW unit cell.Furthermore,the ISGW is implemented to improve the radiation performance of the antenna by alleviating the propagation of surface wave.And an equivalent circuit is investigated to reveal the working principle of ISGW.To demonstrate this methodology,an ISGW filtering antenna operating at a center frequency of 25 GHz is designed,fabricated,and measured.The results show that the antenna achieves a stopband width of 1.6f0(center frequency),an out-of-band suppression level of 21 dB,and a peak realized gain of 8.5 dBi.
基金the "Program for Promoting Maritime Economies with Science and Technology" in Tianjin，the National Natural Science Foundation of China，the Tianjin Research Program of Application Foundation and Advanced Technology，the National Science and Technology Major Project，Seed Foundation of Tianjin University
文摘This paper summarizes the requirements for modem maritime wireless communication networks in the marine environments including the sea- to-sea and sea-to-shore communication scenarios. The existing maritime wireless communication sys- tems are presented and the development of the state-of-the-art maritime communication systems is surveyed. Furthermore, a hierarchical and integrated maritime network architecture is proposed to satisfy the increasing various classes of services which demand different Quality of Service （QoS）. Finally, the open issues for further development of maritime communications are identified.
基金supported by National ScienceFoundation Programs(60536020,60723002)"973"State Key Basic Research Programs(2006CB302800,2006CB921106)
文摘An electro-absorption(EA)modulator is one of key components for optical fiber communications due to the high speed,small size,low voltage and integration ability with other semiconductor devices.A 40 Gb/s InGaAsP/InP multiplequantum-well(MQW)EA modulator monolithically integrated with a semiconductor optical amplifier(SOA)was fabricated for digital communications.The modulator capacitance was reduced to obtain 40 GHz bandwidth,and the SOA section helped reduce the insertion loss from 18 dB to 3 dB.InGaAlAs/InP MQW EA modulators have also been fabricated and characterized for analog optical fiber communications.A low driving voltage of 2.7 V and high spurious free dynamic range of 107 dB·Hz2/3 were estimated by static and dynamic measurements.
文摘The Joy Luck Club written by Chinese American writer Amy Tan depicts the conflicts and reconciliation between the Chinese-born mothers and American-born daughters, reflecting the clashes and fusions of two different cultures. This paper sets out from the intercultural perspective to probe into the cultural factors which contribute to the failure in communication, and strives to get inspirations from the four pair of mothers and daughters to eliminate cross-culture communication barriers.
基金supported in part by the National Natural Science Foundation of China(Nos.62101232 and 62471208)in part by the Guangdong Provincial Natural Science Foundation,China(No.2024A151510098)+4 种基金in part by the Shenzhen Science and Technology Program,China(No.JCYJ20220530114412029)in part by Shenzhen Key Laboratory of Robotics and Computer Vision,China(No.ZDSYS20220330160557001)supported by the National Natural Science Foundation of China(No.62301206)the Zhejiang Provincial Natural Science Foundation of China(No.LQ24F010005)the Starting Research Fund from the Hangzhou Normal University,China(No.4115C50222204114).
文摘Covert unmanned aerial vehicle(UAV)communication has garnered considerable attention in wireless systems for realizing the sustainable low-altitude economy(LAE).This paper investigates the system policy,trajectory design,and resource allocation for energy-efficient aerial networked systems with the aid of an integrated sensing and communications(ISAC)framework,in which multiple UAVs are employed to simultaneously conduct cooperative sensing and covert downlink transmissions to multiple ground users(GUs)in the presence of a mobile warden(Willie).Specifically,to improve the communication covertness,UAVs are strategically switched between jamming(JUAV)and information(IUAV)modes.Additionally,to cope with the mobility of Willie,an unscented Kalman filtering(UKF)-based method is employed to track and predict Willie’s location relying on the delay and Doppler measurements extracted from the ISAC echoes.Capitalizing on the predicted Willie’s location,a real-time energy efficiency(EE)maximization problem is formulated by jointly optimizing the JUAV selection strategy,IUAV-GU scheduling,communication/jamming power allocation,and UAV trajectories design.The formulation takes into account the communication covertness requirement and the maximum transmit power budget,leading to a mixed-integer non-convex fractional programming.To tackle this challenge,the alternating optimization(AO)approach is adopted,which decomposes the original problem into a series of sub-problems,allowing us to obtain an efficient sub-optimal solution.Simulation results demonstrate that the proposed scheme is capable of tracking Willie accurately and offering excellent system EE performance compared to various benchmark schemes adopting existing designs.
基金support from the Natural Science Foundation of China(61975001)National Key R&D Program of China(2018YFB1107205)+1 种基金Beijing Natural Science Foundation(Z190005)the Key R&D Program of Guangdong Province(2018B030329001).
文摘Quantum communications aim to share encryption keys between the transmitters and receivers governed by the laws of quantum mechanics.Integrated quantum photonics offers significant advantages of dense integration,high stability and scalability,which enables a vital platform for the implementation of quantum information processing and quantum communications.This article reviews recent experimental progress and advances in the development of integrated quantum photonic devices and systems for quantum communications and quantum networks.
文摘Ningxia is an ethnic gathering area boasting abundant tourism and cultural resources.Developing the cause of tourism and culture is an important way to encourage all ethnic groups to respect differences,embrace diversity,and demonstrate their interactions,exchanges,and integration in tourism activities.As an important preserve of the distinctive cultures of the Chinese nation and a prominent world tourist destination,Ningxia should strive to foster and consolidate the sense of a community with a shared future for the Chinese nation in developing its tourism and culture under the new historical conditions.It is imperative to advance the prosperity and development of tourism and culture in boosting ethnic interactions,exchanges,and integration through the formulation of tourism and cultural policies and plans,as well as the development and design of tourism and cultural projects.
基金This work was financially supported by the Key Field R&D Program of Guangdong Province under Grant No.2021B0101300001the National Key R&D Program of China under Grant No.2022YFB3605003+3 种基金the Nation⁃al Natural Science Foundation of China under Grant Nos.52192614 and 62135013Beijing Natural Science Foundation under Grant No.4222077Beijing Science and Technology Plan under Grant No.Z221100002722019Guangdong Basic and Applied Basic Research Foundation under Grant No.2022B1515120081.
文摘A solar-blind multi-quantum well(MQW)structure wafer based on AlGaN materials is epitaxial growth by metal-organic chemical vapor deposition(MOCVD).The monolithically integrated photonic chips including light-emitting diodes(LEDs),waveguides,and photodetec-tors(PDs)are presented.The results of the finite-difference time-domain(FDTD)simulation confirm the strong light constraint of the wave-guide designed with the triangular structure in the optical coupling region.Furthermore,in virtue of predominant ultraviolet transverse mag-netic(TM)modes,the solar blind optical signal is more conducive to lateral transmission along the waveguide inside the integrated chip.The integrated PDs demonstrate sufficient photosensitivity to the optical signal from the integrated LEDs.When the LEDs are operated at 100 mA current,the photo-to-dark current ratio(PDCR)of the integrated PD is about seven orders of magnitude.The responsivity,specific detectivity,and external quantum efficiency of the integrated self-driven PD are 74.89 A/W,4.22×1013 Jones,and 3.38×104%,respectively.The stable on-chip optical information transmission capability of the monolithically integrated photonic chips confirms the great potential for application in large-scale on-chip optical communication in the future.
文摘The research on scheduling and heat integration of batch process plays an important role in reducing energy consumption,improving production efficiency and enhancing the competitiveness of industries.The complexity and difficulty of the model solving are increased due to the comprehensive consideration of both scheduling and heat integration.In this paper,the mixed integer nonlinear programming(MINLP) mathematical model of multi-product plant heat integration optimization with the goal of energy-saving annual profit(EAP) is established.The simultaneous optimization and sequential optimization are carried out respectively by bi-level programming(BP) based on the genetic algorithm(GA),and the calculation results are compared.EAP better captures the trade-off relationship between scheduling schemes,energy-saving profits,and equipment costs.The bi-level programming approach based on GA categorizes variables into integer and real types,enabling structural optimization and parameter optimization of the heat exchanger network.This,in turn,enhances solution efficiency and overcomes the limitations of conventional optimization algorithms in terms of solution speed and quality.Two examples show that the EAP of indirect heat integration considering the storage tank are 21% and 2% higher than that of the direct heat integration,and EAP of the simultaneous optimization are26% and 6% higher than that of the sequential optimization.The example demonstrates that the model and algorithm are applicable to batch multi-product plants,such as those in the chemical,pharmaceutical,and food industries,and possess strong practicality and innovation.
基金National Natural Science Foundation of China under Grant 62571248 and Grant 62201266Key Laboratory of Intelligent Space TTC&O(Space Engineering University),Ministry of Education under Grant CYK2025-01-12。
文摘Integrated sensing and communication(ISAC)is an appealing approach to address spectrum congestion and beamforming is an effective method to realize ISAC.In this paper,we investigate the beamforming design problem for multiple-input multipleoutput(MIMO)ISAC systems and propose to maximize the radar beampattern gain of the target direction while ensuring the signal-to-interference-plus-noise ratio(SINR)constraints of communication users.Particularly,we discuss two cases of ISAC transmit beamforming,i.e.,Case-Ⅰand Case-Ⅱ,which do not have and do have the dedicated probing signal,respectively.For these two cases of transmit beamforming design problems,we start from the single-user scenario and provide the closed-form solutions for MIMO ISAC beamforming vectors.Then,we consider the multiuser scenario and utilize the semidefinite relaxation technique to convert the beamforming design problems into convex semidefinite programming problems.Furthermore,we investigate the impact of the channel correlation between radar and communication on the performance gain of MIMO ISAC systems and characterize the performance tradeoff.Numerical results validate that the dedicated probing signal is unnecessary in the single-user scenario,whereas it has a slight improvement in target detection performance at low SINR thresholds in the multi-user scenario.It is also shown that the stronger the correlation between radar and communication channels,the greater the performance gain of the system.
基金supported by the National Key Research&Development Program of China(No.2024YFB3910102).
文摘The rapid expansion of the low-altitude economy is driving strong demand for highly accurate and reliable positioning technologies to support diverse aerial operations.This review examines core positioning methodologies within the low-altitude intelligent network(LAIN)framework,beginning with an analysis of positioning requirements and performance metrics for low-altitude flight scenarios.It systematically assesses the principles,strengths,and limitations of mainstream positioning systems,including Global Navigation Satellite Systems(GNSS),terrestrial wireless positioning,and autonomous navigation,and it surveys prevalent integrated and cooperative positioning schemes.Our analysis demonstrates that standalone positioning technologies are inadequate in complex low-altitude settings,underscoring the pivotal role of multi-source fusion and unmanned aerial vehicle(UAV)swarm cooperative positioning as future trends.To address infrastructure gaps and high deployment costs in current LAIN systems,we propose a“space−air−ground”integrated and cooperative positioning architecture centered on GNSS and the 5th generation mobile communication technology(5G).The ground layer integrates 5G and GNSS for wide-area enhanced positioning.The aerial layer uses 5G aircraft-to-everything(A2X)and sidelink(SL)communications to build self-organizing networks for cooperative UAV localization.The space layer leverages low Earth orbit(LEO)satellites to overcome coverage limitations in communication and positioning.This hierarchical architecture reduces deployment costs through infrastructure reuse and enables deep integration of communication and navigation capabilities.By supporting collaborative enhancement across all three domains,the framework improves positioning robustness and delivers cost-effective,ubiquitous,and highly reliable positioning services.Finally,we outline promising research directions.This review aims to provide a systematic reference and a novel architectural perspective for the ongoing development of LAIN.
