With the rapid development of urban rail transit,the existing track detection has some problems such as low efficiency and insufficient detection coverage,so an intelligent and automatic track detectionmethod based on...With the rapid development of urban rail transit,the existing track detection has some problems such as low efficiency and insufficient detection coverage,so an intelligent and automatic track detectionmethod based onUAV is urgently needed to avoid major safety accidents.At the same time,the geographical distribution of IoT devices results in the inefficient use of the significant computing potential held by a large number of devices.As a result,the Dispersed Computing(DCOMP)architecture enables collaborative computing between devices in the Internet of Everything(IoE),promotes low-latency and efficient cross-wide applications,and meets users’growing needs for computing performance and service quality.This paper focuses on examining the resource allocation challenge within a dispersed computing environment that utilizes UAV inspection tracks.Furthermore,the system takes into account both resource constraints and computational constraints and transforms the optimization problem into an energy minimization problem with computational constraints.The Markov Decision Process(MDP)model is employed to capture the connection between the dispersed computing resource allocation strategy and the system environment.Subsequently,a method based on Double Deep Q-Network(DDQN)is introduced to derive the optimal policy.Simultaneously,an experience replay mechanism is implemented to tackle the issue of increasing dimensionality.The experimental simulations validate the efficacy of the method across various scenarios.展开更多
The rapid growth of mobile data traffic has caused great pressure on the limited spectrum resources,and there must be some better methods to deal with this problem.The innovative technology of Long-Term Evolution(LTE)u...The rapid growth of mobile data traffic has caused great pressure on the limited spectrum resources,and there must be some better methods to deal with this problem.The innovative technology of Long-Term Evolution(LTE)using the unlicensed spectrum,known as LTE-Unlicensed(LTE-U),has been proposed to effectively alleviate the shortage of authorized band resources.LTE-U has explored a lot of potential capacity in mobile communication systems with limited authorized spectrum resources,and improved the spectrum utilization of unauthorized frequency bands.However,LTE-U is still facing challenges in its application.In this paper,we summarize the key features of LTE-U and the coex-istence of LTE-U with Wi-Fi in the unlicensed Spectrum.We analyze the key technologies(including carrier aggregation,HARQ,interference cancelation,and centralized scheduling),the operating modes and deployment scenarios(including carrier aggregation LTE-U,duty cycle LTE-U,and standalone LTE-U),and the advantages(including anchored LTE-U and Standalone LTE-U scenarios),as well as main technical challenges.We then address the different management mechanisms of LTE-U and Wi-Fi(including the differences between the MAC layer and physical layer),the types of coexistence technology classification(including channel separation and channel sharing technologies),and directions for future work.We hope that this comprehensive survey spurs further research in this promising area.展开更多
This paper reviews positioning systems in the context of communication systems. First, the basic positioning technique is described for location based ser- vice (LBS) in mobile communication systems. Then the high i...This paper reviews positioning systems in the context of communication systems. First, the basic positioning technique is described for location based ser- vice (LBS) in mobile communication systems. Then the high integrity global posi- tioning system (iGPS) is introduced in terms of aspects of what it is and how the low Earth orbit (LEO) Iridium telecommunication satellites enhance the global posi- tioning system (GPS). Emphasis is on the Chinese Area Positioning System (CAPS) which is mainly based on commercial geostationary (GEO) communication satellites, including decommissioned GEO and inclined geosynchronous communication satel- lites. Characterized by its low cost, high flexibility, wide-area coverage and ample frequency resources, a distinctive feature of CAPS is that its navigation messages are generated on the ground, then uploaded to and forwarded by the communication satellites. Fundamental principles and key technologies applied in the construction of CAPS are presented in detail from the CAPS validation phase to its experimental system setup. A prospective view of CAPS has concluded it to be a seamless, high ac- curacy, large capacity navigation and communication system which can be achieved by expanding it world wide and enhancing it with LEO satellites and mobile base stations. Hence, this system is a potential candidate for the next generation of radio navigation after GPS.展开更多
文摘With the rapid development of urban rail transit,the existing track detection has some problems such as low efficiency and insufficient detection coverage,so an intelligent and automatic track detectionmethod based onUAV is urgently needed to avoid major safety accidents.At the same time,the geographical distribution of IoT devices results in the inefficient use of the significant computing potential held by a large number of devices.As a result,the Dispersed Computing(DCOMP)architecture enables collaborative computing between devices in the Internet of Everything(IoE),promotes low-latency and efficient cross-wide applications,and meets users’growing needs for computing performance and service quality.This paper focuses on examining the resource allocation challenge within a dispersed computing environment that utilizes UAV inspection tracks.Furthermore,the system takes into account both resource constraints and computational constraints and transforms the optimization problem into an energy minimization problem with computational constraints.The Markov Decision Process(MDP)model is employed to capture the connection between the dispersed computing resource allocation strategy and the system environment.Subsequently,a method based on Double Deep Q-Network(DDQN)is introduced to derive the optimal policy.Simultaneously,an experience replay mechanism is implemented to tackle the issue of increasing dimensionality.The experimental simulations validate the efficacy of the method across various scenarios.
文摘The rapid growth of mobile data traffic has caused great pressure on the limited spectrum resources,and there must be some better methods to deal with this problem.The innovative technology of Long-Term Evolution(LTE)using the unlicensed spectrum,known as LTE-Unlicensed(LTE-U),has been proposed to effectively alleviate the shortage of authorized band resources.LTE-U has explored a lot of potential capacity in mobile communication systems with limited authorized spectrum resources,and improved the spectrum utilization of unauthorized frequency bands.However,LTE-U is still facing challenges in its application.In this paper,we summarize the key features of LTE-U and the coex-istence of LTE-U with Wi-Fi in the unlicensed Spectrum.We analyze the key technologies(including carrier aggregation,HARQ,interference cancelation,and centralized scheduling),the operating modes and deployment scenarios(including carrier aggregation LTE-U,duty cycle LTE-U,and standalone LTE-U),and the advantages(including anchored LTE-U and Standalone LTE-U scenarios),as well as main technical challenges.We then address the different management mechanisms of LTE-U and Wi-Fi(including the differences between the MAC layer and physical layer),the types of coexistence technology classification(including channel separation and channel sharing technologies),and directions for future work.We hope that this comprehensive survey spurs further research in this promising area.
基金supported bythe Pilot Program for the New and Interdisciplinary Subjects of the Chinese Academy of Sciences(Grant No. KJCX2-EW-J01)the Knowledge Innovation Program of the Chinese Academy of Sciences (Grant No. KGCX2-EW-407-1)
文摘This paper reviews positioning systems in the context of communication systems. First, the basic positioning technique is described for location based ser- vice (LBS) in mobile communication systems. Then the high integrity global posi- tioning system (iGPS) is introduced in terms of aspects of what it is and how the low Earth orbit (LEO) Iridium telecommunication satellites enhance the global posi- tioning system (GPS). Emphasis is on the Chinese Area Positioning System (CAPS) which is mainly based on commercial geostationary (GEO) communication satellites, including decommissioned GEO and inclined geosynchronous communication satel- lites. Characterized by its low cost, high flexibility, wide-area coverage and ample frequency resources, a distinctive feature of CAPS is that its navigation messages are generated on the ground, then uploaded to and forwarded by the communication satellites. Fundamental principles and key technologies applied in the construction of CAPS are presented in detail from the CAPS validation phase to its experimental system setup. A prospective view of CAPS has concluded it to be a seamless, high ac- curacy, large capacity navigation and communication system which can be achieved by expanding it world wide and enhancing it with LEO satellites and mobile base stations. Hence, this system is a potential candidate for the next generation of radio navigation after GPS.