Wireless sensor network(WSN)is considered as the fastest growing technology pattern in recent years because of its applicability in varied domains.Many sensor nodes with different sensing functionalities are deployed ...Wireless sensor network(WSN)is considered as the fastest growing technology pattern in recent years because of its applicability in varied domains.Many sensor nodes with different sensing functionalities are deployed in the monitoring area to collect suitable data and transmit it to the gateway.Ensuring communications in heterogeneous WSNs,is a critical issue that needs to be studied.In this research paper,we study the system performance of a heterogeneous WSN using LoRa–Zigbee hybrid communication.Specifically,two Zigbee sensor clusters and two LoRa sensor clusters are used and combined with two Zigbee-to-LoRa converters to communicate in a network managed by a LoRa gateway.The overall system integrates many different sensors in terms of types,communication protocols,and accuracy,which can be used in many applications in realistic environments such as on land,under water,or in the air.In addition to this,a synchronous management software on ThingSpeak Web server and Blynk app is designed.In the proposed system,the token ring protocol in Zigbee network and polling mechanism in LoRa network is used.The system can operate with a packet loss rate of less than 0.5%when the communication range of the Zigbee network is 630 m,and the communication range of the LoRa network is 3.7 km.On the basis of the digital results collected on the management software,this study proves tremendous improvements in the system performance.展开更多
In the upcoming sixth-generation(6G)era,the demand for constructing a wide-area time-sensitive Internet of Things(IoT)continues to increase.As conventional cellular technologies are difficult to directly use for wide-...In the upcoming sixth-generation(6G)era,the demand for constructing a wide-area time-sensitive Internet of Things(IoT)continues to increase.As conventional cellular technologies are difficult to directly use for wide-area time-sensitive IoT,it is beneficial to use non-terrestrial infrastructures,including satellites and unmanned aerial vehicles(UAVs).Thus,we can build a non-terrestrial network(NTN)using a cell-free architecture.Driven by the time-sensitive requirements and uneven distribution of IoT devices,the NTN must be empowered using mobile edge computing(MEC)while providing oasisoriented on-demand coverage for devices.Nevertheless,communication and MEC systems are coupled with each other under the influence of a complex propagation environment in the MEC-empowered NTN,which makes it difficult to coordinate the resources.In this study,we propose a process-oriented framework to design communication and MEC systems in a time-division manner.In this framework,large-scale channel state information(CSI)is used to characterize the complex propagation environment at an affordable cost,where a nonconvex latency minimization problem is formulated.Subsequently,the approximated problem is provided,and it can be decomposed into sub-problems.These sub-problems are then solved iteratively.The simulation results demonstrated the superiority of the proposed process-oriented scheme over other algorithms,implied that the payload deployments of UAVs should be appropriately predesigned to improve the efficiency of using resources,and confirmed that it is advantageous to integrate NTN with MEC for wide-area time-sensitive IoT.展开更多
The use of Global Navigation Satellite Systems (GNSS) for positioning has revolutionized the way location data is be- ing collected. The NAVigation System with Time And Ranging Global Positioning System (GPS), which i...The use of Global Navigation Satellite Systems (GNSS) for positioning has revolutionized the way location data is be- ing collected. The NAVigation System with Time And Ranging Global Positioning System (GPS), which is a principal component of the global navigation satellite system (GNSS);is a satellite-based radio navigation system that provides positions of points of interest and time information to users. GPS positional accuracy can be improved by using differential corrections obtained through a technique called Differential GPS (DGPS), which is known to provide the most accurate positioning results. Differential correction can be applied in real time at the data collection phase or in the of- fice, at the post-processing phase. DGPS is generally used for positioning purposes through static or kinematics GPS surveys. In static GPS surveys, one receiver is placed at a point whose coordinates are known and the other receiver is placed over a point whose coordinates are desired. In kinematic surveys, one receiver remains at one point (base station) normally with known coordinates, and the other receiver (rover) moves from point to point in the project area. Kinematic surveys in which points positions are computed on-the-fly (OTF) are known as real-time kinematic (RTK). RTK surveys provide real-time locations of points of interest needed in many applications. Positioning with wide-area GNSS networks is basically based on the DGPS and RTK concepts. Observables from a network of a finite number of GPS receivers over an area are processed by a server at a central location (network server) and made available to the users of the network later or in real-time through radio-based, satellite, or wireless communications. This article provides a review of the concept and application of positioning with wide-area GNSS networks.展开更多
远距离无线电(Long Range Radio,LoRa)网络具有连接数量多、传输距离远、功耗低的特点,然而海量LoRa终端的接入将使得LoRa网络的数据包碰撞率激增,制约网络传输性能。为优化LoRa网络参数分配和功率控制,以A类终端设备建立了LoRa网络冲...远距离无线电(Long Range Radio,LoRa)网络具有连接数量多、传输距离远、功耗低的特点,然而海量LoRa终端的接入将使得LoRa网络的数据包碰撞率激增,制约网络传输性能。为优化LoRa网络参数分配和功率控制,以A类终端设备建立了LoRa网络冲突率的计算公式,提出了一种基于传输时间的LoRa网络参数分配与功率控制算法,其目标是最小化网络数据包传输平均冲突率时最小化网络能耗,通过优化网络整体节点的参数和发送功率来实现。仿真结果表明,与传统的AAPA等参数分配算法相比,基于传输时间的LoRa网络参数分配与功率控制算法能显著降低冲突率24.8%以上,降低网络能耗30.7%以上。展开更多
传统的工业无线状态检测存在传输距离近、成本高、工作不稳定、可容纳节点数量少等缺陷。对此,LoRa作为低功耗广域网数据传输技术之一,它与传统的无线传感网络技术相比,具有低功耗、距离远、抗干扰性强等优势。设计并实现了基于时分复用...传统的工业无线状态检测存在传输距离近、成本高、工作不稳定、可容纳节点数量少等缺陷。对此,LoRa作为低功耗广域网数据传输技术之一,它与传统的无线传感网络技术相比,具有低功耗、距离远、抗干扰性强等优势。设计并实现了基于时分复用的LoRa自组网设计,采用STM32F051K8U6作为控制器完成数据的处理和分析,并以SX1278作为核心器件的无线模块来实现网关与各节点的数据互传。上位机的开发环境采用Microsoft Visual Studio 2012。在室外环境对系统进行了数据和距离测试。实验结果表明,该系统具有运行稳定、操作简单、传输距离远、丢包率低等特点。展开更多
随着物联网的快速发展,低功耗设备的故障诊断成为一个重要挑战。传统的故障诊断方法在实时性和准确性上存在局限。基于远距离无线电(Long Range Radio,LoRa)的低功耗远程通信和卷积神经网络(Convolutional Neural Networks,CNN)的深度...随着物联网的快速发展,低功耗设备的故障诊断成为一个重要挑战。传统的故障诊断方法在实时性和准确性上存在局限。基于远距离无线电(Long Range Radio,LoRa)的低功耗远程通信和卷积神经网络(Convolutional Neural Networks,CNN)的深度学习能力,设计一种高效的故障诊断系统,能够在长距离和低带宽的环境下完成设备状态监测与故障诊断。实验结果表明,该系统能够显著提升故障诊断的准确性和实时性,同时有效降低系统能耗,为低功耗设备的智能监控与故障检测提供新的解决方案。展开更多
为实现景区能耗的高效监测与智能管理,提升能源利用效率,设计一套基于远距离无线电(Long Range Radio,LoRa)低功耗广域网技术的能耗监测与管理系统。通过构建三层系统架构,结合动态节点状态感知、设备能效优化策略生成及动态负载调控等...为实现景区能耗的高效监测与智能管理,提升能源利用效率,设计一套基于远距离无线电(Long Range Radio,LoRa)低功耗广域网技术的能耗监测与管理系统。通过构建三层系统架构,结合动态节点状态感知、设备能效优化策略生成及动态负载调控等关键技术,实现对景区各类用能设备的实时采集与智能控制。实验验证表明,系统在异常识别、策略生成和指令执行等方面均达到预期目标。研究结果表明,该系统具备部署灵活、响应迅速、节能效果显著等优势,为智慧景区建设提供可行的技术路径。展开更多
针对输电线路状态监测中传统通信技术覆盖不足、功耗高等问题,设计一种基于远距离无线电(Long Range Radio,LoRa)无线通信的输电线路状态监测系统。该系统采用分层架构设计,通过部署于杆塔的传感终端采集数据,利用LoRa技术实现远距离低...针对输电线路状态监测中传统通信技术覆盖不足、功耗高等问题,设计一种基于远距离无线电(Long Range Radio,LoRa)无线通信的输电线路状态监测系统。该系统采用分层架构设计,通过部署于杆塔的传感终端采集数据,利用LoRa技术实现远距离低功耗传输,经网关汇聚后上传至云端平台进行故障诊断与可视化分析。实测结果表明,该系统在郊区环境下通信距离可达8.2 km,终端休眠功耗低于1.5μA,数据丢包率小于3%。相较于传统4G监测方案,能耗降低72%,为输电线路广域监测提供高可靠性解决方案。展开更多
针对分布式电能计量系统中传统通信技术存在的覆盖盲区大、终端功耗高、部署成本高昂等瓶颈问题,研究远距离无线电(Long Range Radio,LoRa)技术在复杂环境下的适应性,提出基于长距离广域网(Long Range Wide Area Network,LoRaWAN)协议...针对分布式电能计量系统中传统通信技术存在的覆盖盲区大、终端功耗高、部署成本高昂等瓶颈问题,研究远距离无线电(Long Range Radio,LoRa)技术在复杂环境下的适应性,提出基于长距离广域网(Long Range Wide Area Network,LoRaWAN)协议的星形组网架构,设计终端侧STM32+SX1276的超低功耗硬件方案,构建网关侧多通道集中器部署策略,最后在3类典型场景下验证了所提方案的性能。展开更多
Metadata prefetching and data placement play a critical role in enhancing access performance for file systems operating over wide-area networks.However,developing effective strategies for metadata prefetching in envir...Metadata prefetching and data placement play a critical role in enhancing access performance for file systems operating over wide-area networks.However,developing effective strategies for metadata prefetching in environments with concurrent workloads and for data placement across distributed networks remains a significant challenge.This study introduces novel and efficient methodologies for metadata prefetching and data placement,leveraging fine-grained control of prefetching strategies and variable-sized data fragment writing to optimize the I/O bandwidth of distributed file systems.The proposed metadata prefetching technique employs dynamic workload analysis to identify dominant workload patterns and adaptively refines prefetching policies,thereby boosting metadata access efficiency under concurrent scenarios.Meanwhile,the data placement strategy improves write performance by storing data fragments locally within the nearest data center and transmitting only the fragment location metadata to the remote data center hosting the original file.Experimental evaluations using real-world system traces demonstrate that the proposed approaches reduce metadata access times by up to 33.5%and application data access times by 17.19%compared to state-of-the-art techniques.展开更多
文摘Wireless sensor network(WSN)is considered as the fastest growing technology pattern in recent years because of its applicability in varied domains.Many sensor nodes with different sensing functionalities are deployed in the monitoring area to collect suitable data and transmit it to the gateway.Ensuring communications in heterogeneous WSNs,is a critical issue that needs to be studied.In this research paper,we study the system performance of a heterogeneous WSN using LoRa–Zigbee hybrid communication.Specifically,two Zigbee sensor clusters and two LoRa sensor clusters are used and combined with two Zigbee-to-LoRa converters to communicate in a network managed by a LoRa gateway.The overall system integrates many different sensors in terms of types,communication protocols,and accuracy,which can be used in many applications in realistic environments such as on land,under water,or in the air.In addition to this,a synchronous management software on ThingSpeak Web server and Blynk app is designed.In the proposed system,the token ring protocol in Zigbee network and polling mechanism in LoRa network is used.The system can operate with a packet loss rate of less than 0.5%when the communication range of the Zigbee network is 630 m,and the communication range of the LoRa network is 3.7 km.On the basis of the digital results collected on the management software,this study proves tremendous improvements in the system performance.
基金the National Key R&D Program of China(2018YFA0701601 and 2020YFA0711301)the National Natural Science Foundation of China(61771286,61941104,and 61922049)the Tsinghua University-China Mobile Communications Group Co.,Ltd.Joint Institute.
文摘In the upcoming sixth-generation(6G)era,the demand for constructing a wide-area time-sensitive Internet of Things(IoT)continues to increase.As conventional cellular technologies are difficult to directly use for wide-area time-sensitive IoT,it is beneficial to use non-terrestrial infrastructures,including satellites and unmanned aerial vehicles(UAVs).Thus,we can build a non-terrestrial network(NTN)using a cell-free architecture.Driven by the time-sensitive requirements and uneven distribution of IoT devices,the NTN must be empowered using mobile edge computing(MEC)while providing oasisoriented on-demand coverage for devices.Nevertheless,communication and MEC systems are coupled with each other under the influence of a complex propagation environment in the MEC-empowered NTN,which makes it difficult to coordinate the resources.In this study,we propose a process-oriented framework to design communication and MEC systems in a time-division manner.In this framework,large-scale channel state information(CSI)is used to characterize the complex propagation environment at an affordable cost,where a nonconvex latency minimization problem is formulated.Subsequently,the approximated problem is provided,and it can be decomposed into sub-problems.These sub-problems are then solved iteratively.The simulation results demonstrated the superiority of the proposed process-oriented scheme over other algorithms,implied that the payload deployments of UAVs should be appropriately predesigned to improve the efficiency of using resources,and confirmed that it is advantageous to integrate NTN with MEC for wide-area time-sensitive IoT.
文摘The use of Global Navigation Satellite Systems (GNSS) for positioning has revolutionized the way location data is be- ing collected. The NAVigation System with Time And Ranging Global Positioning System (GPS), which is a principal component of the global navigation satellite system (GNSS);is a satellite-based radio navigation system that provides positions of points of interest and time information to users. GPS positional accuracy can be improved by using differential corrections obtained through a technique called Differential GPS (DGPS), which is known to provide the most accurate positioning results. Differential correction can be applied in real time at the data collection phase or in the of- fice, at the post-processing phase. DGPS is generally used for positioning purposes through static or kinematics GPS surveys. In static GPS surveys, one receiver is placed at a point whose coordinates are known and the other receiver is placed over a point whose coordinates are desired. In kinematic surveys, one receiver remains at one point (base station) normally with known coordinates, and the other receiver (rover) moves from point to point in the project area. Kinematic surveys in which points positions are computed on-the-fly (OTF) are known as real-time kinematic (RTK). RTK surveys provide real-time locations of points of interest needed in many applications. Positioning with wide-area GNSS networks is basically based on the DGPS and RTK concepts. Observables from a network of a finite number of GPS receivers over an area are processed by a server at a central location (network server) and made available to the users of the network later or in real-time through radio-based, satellite, or wireless communications. This article provides a review of the concept and application of positioning with wide-area GNSS networks.
文摘远距离无线电(Long Range Radio,LoRa)网络具有连接数量多、传输距离远、功耗低的特点,然而海量LoRa终端的接入将使得LoRa网络的数据包碰撞率激增,制约网络传输性能。为优化LoRa网络参数分配和功率控制,以A类终端设备建立了LoRa网络冲突率的计算公式,提出了一种基于传输时间的LoRa网络参数分配与功率控制算法,其目标是最小化网络数据包传输平均冲突率时最小化网络能耗,通过优化网络整体节点的参数和发送功率来实现。仿真结果表明,与传统的AAPA等参数分配算法相比,基于传输时间的LoRa网络参数分配与功率控制算法能显著降低冲突率24.8%以上,降低网络能耗30.7%以上。
文摘传统的工业无线状态检测存在传输距离近、成本高、工作不稳定、可容纳节点数量少等缺陷。对此,LoRa作为低功耗广域网数据传输技术之一,它与传统的无线传感网络技术相比,具有低功耗、距离远、抗干扰性强等优势。设计并实现了基于时分复用的LoRa自组网设计,采用STM32F051K8U6作为控制器完成数据的处理和分析,并以SX1278作为核心器件的无线模块来实现网关与各节点的数据互传。上位机的开发环境采用Microsoft Visual Studio 2012。在室外环境对系统进行了数据和距离测试。实验结果表明,该系统具有运行稳定、操作简单、传输距离远、丢包率低等特点。
文摘随着物联网的快速发展,低功耗设备的故障诊断成为一个重要挑战。传统的故障诊断方法在实时性和准确性上存在局限。基于远距离无线电(Long Range Radio,LoRa)的低功耗远程通信和卷积神经网络(Convolutional Neural Networks,CNN)的深度学习能力,设计一种高效的故障诊断系统,能够在长距离和低带宽的环境下完成设备状态监测与故障诊断。实验结果表明,该系统能够显著提升故障诊断的准确性和实时性,同时有效降低系统能耗,为低功耗设备的智能监控与故障检测提供新的解决方案。
文摘为实现景区能耗的高效监测与智能管理,提升能源利用效率,设计一套基于远距离无线电(Long Range Radio,LoRa)低功耗广域网技术的能耗监测与管理系统。通过构建三层系统架构,结合动态节点状态感知、设备能效优化策略生成及动态负载调控等关键技术,实现对景区各类用能设备的实时采集与智能控制。实验验证表明,系统在异常识别、策略生成和指令执行等方面均达到预期目标。研究结果表明,该系统具备部署灵活、响应迅速、节能效果显著等优势,为智慧景区建设提供可行的技术路径。
文摘针对输电线路状态监测中传统通信技术覆盖不足、功耗高等问题,设计一种基于远距离无线电(Long Range Radio,LoRa)无线通信的输电线路状态监测系统。该系统采用分层架构设计,通过部署于杆塔的传感终端采集数据,利用LoRa技术实现远距离低功耗传输,经网关汇聚后上传至云端平台进行故障诊断与可视化分析。实测结果表明,该系统在郊区环境下通信距离可达8.2 km,终端休眠功耗低于1.5μA,数据丢包率小于3%。相较于传统4G监测方案,能耗降低72%,为输电线路广域监测提供高可靠性解决方案。
文摘针对分布式电能计量系统中传统通信技术存在的覆盖盲区大、终端功耗高、部署成本高昂等瓶颈问题,研究远距离无线电(Long Range Radio,LoRa)技术在复杂环境下的适应性,提出基于长距离广域网(Long Range Wide Area Network,LoRaWAN)协议的星形组网架构,设计终端侧STM32+SX1276的超低功耗硬件方案,构建网关侧多通道集中器部署策略,最后在3类典型场景下验证了所提方案的性能。
基金funded by the National Natural Science Foundation of China under Grant No.62362019the Hainan Provincial Natural Science Foundation of China under Grant No.624RC482.
文摘Metadata prefetching and data placement play a critical role in enhancing access performance for file systems operating over wide-area networks.However,developing effective strategies for metadata prefetching in environments with concurrent workloads and for data placement across distributed networks remains a significant challenge.This study introduces novel and efficient methodologies for metadata prefetching and data placement,leveraging fine-grained control of prefetching strategies and variable-sized data fragment writing to optimize the I/O bandwidth of distributed file systems.The proposed metadata prefetching technique employs dynamic workload analysis to identify dominant workload patterns and adaptively refines prefetching policies,thereby boosting metadata access efficiency under concurrent scenarios.Meanwhile,the data placement strategy improves write performance by storing data fragments locally within the nearest data center and transmitting only the fragment location metadata to the remote data center hosting the original file.Experimental evaluations using real-world system traces demonstrate that the proposed approaches reduce metadata access times by up to 33.5%and application data access times by 17.19%compared to state-of-the-art techniques.
