共查询到19条相似文献,搜索用时 78 毫秒
1.
LoRa是一种用于广域物联网应用的低功耗通信技术,具有远距离、超低功耗等特点.LoRa采用基于Chirp(线性调频)信号的扩频调制技术,通过对Chirp信号进行循环移位得到调制信号,其传输信息由符号起始位置的初始频率偏移所承载.其通信性能极易受定时偏差和频率偏差的影响.提出一种针对LoRa技术的联合同步及频偏估计算法,根据LoRa循环移位的特点,通过推导时偏和频偏的数学模型,联立方程组求解得到精确的估计值,用于准确纠正LoRa技术中的定时偏差及频率偏差.仿真结果验证了该算法对同步和频偏估计的准确性,能够满足实际场景下的通信需求. 相似文献
2.
3.
4.
针对当前大部分LoRa网络因终端采用静态参数配置而导致的网络灵活性和通信效率不高等问题,提出了一种基于正交遗传算法改善LoRa网络性能的动态参数选择方法。分析了不同参数配置对网络通信性能的影响,针对LoRa网络建立信道冲突和链路预算模型,通过引入基于多目标遗传算法的动态参数选择方法求解该模型,最终获得具有最小冲突概率的参数集。通过对超过10 000台设备的单网关LoRa网络的运行结果表明,所提出的动态参数选择算法可将网络的分组交付率(Packet Delivery Rate,PDR)提高30%,显著提高了网络在不同应用场景下的适应性和扩展能力。 相似文献
5.
6.
7.
8.
高速全数字解调中并行载波同步的研究 总被引:2,自引:0,他引:2
载波同步是解调系统中的统解调系统,对全数字系统的中频采样、并行化结构进行了介绍,并针对载波同步技术的并行化应用进行了分析,给出了适应并行系统的并行载波同步算法.最后利用Matlab软件中的Simulink工具进行系统和载波同步模块的仿真,并给出仿真结果和主要指标,证明了本研究具有实用意义. 相似文献
9.
10.
在信号解调中,使用锁相环可取得较好的解调信号。以调频波和调幅波为例,通过用MATLAB 编程与Simulink
现有组件两种方法对载波同步进行建模与仿真,并详细给出仿真设计原理以及合理选择仿真参数的方法。最后,对仿真
结果进行深入分析,并比较两种方法的可行性与优缺点。 相似文献
11.
物联网体系结构研究与探讨 总被引:3,自引:0,他引:3
物联网是一个十分复杂而又庞大的系统,其体系结构是影响未来发展应用的关键所在。通过对现有物联网技术文献和体系结构实例的分析,提出了一种具有感知层、接入层、网络层和应用层的4层次物联网体系结构参考模型,并对各层所实现的主要功能进行了讨论阐述。这样一个通用的参考模型呈现出了泛在化、智能化的物联网基本特征。 相似文献
12.
With the rapid development of Internet of Things and mobile communication technology, great changes have been brought
to traditional agricultural production. Aiming at the fine production and management of crops in greenhouse, an intelligent green-
house system based on Internet of Things is designed. Agricultural production personnel can obtain real-time and remote environ-
mental data such as air temperature and humidity, soil moisture, carbon dioxide concentration, light intensity and other environmen-
tal data through mobile phones and mobile terminals, and can also control multiple solenoid valves and frequency converters in or-
der to improve the quality and yield of agricultural products. Remote irrigation and precise fertilization are achieved. The experimen-
tal results show that the system can effectively realize the fine management of crops, help customers to improve production, reduce
costs and increase revenue. 相似文献
13.
Intelligent products are an undeniable asset for efficient product lifecycle management (PLM), providing ways to capture events related to physical objects at various locations and times. Today and more than ever before, PLM tools and systems must be built upon standards for enhancing interoperability among all product stakeholders and developing tools independent of specific vendors, applications, and operating systems. Based on this observation, this paper develops strategies to improve “information sustainability” in PLM environments using standardized communication interfaces defined by a recent standard proposal named quantum lifecycle management (QLM) messaging standards. More concretely, data synchronization models based upon QLM standards are developed to enable the synchronization of product-related information among various systems, networks, and organizations involved throughout the product lifecycle. Our proposals are implemented and assessed based on two distinct platforms defined in the healthcare and home automation sectors. 相似文献
14.
15.
转换器标记语言的特性是非常适用于物联网中感应层次中传感器间信息的传输,它也是数据交换标准的关键,对未来的物联网发展起很重要的作用。文章主要介绍了TML的相关概念,进一步总结了其特点,并分析了其应用现状和前景。 相似文献
16.
杨扬 《计算机测量与控制》2018,26(6):49-52
针对ZigBee、WiFi、GPRS传统无线传感技术在大范围农场等温室环境监测系统的不足,本文提出了一种基于LoRa技术的低功耗农场环境监测系统。该系统依托物联网思想,分三层结构。其中感知层作为信息采集部分由MSP430单片机、温湿度传感器和光照强度传感器等组成;网络层采用LoRa无线扩频通信技术进行数据传输,可以实现定点、省电、透传和监听四种模式;应用层对网络层传输的数据进行处理和保存,最终实现灯光控制、灌溉控制、降温控制和人机控制。 相似文献
17.
Ibrahim S. Alsukayti 《计算机科学技术学报》2022,37(2):344-368
The development of IP-based Internet of Things (IoT) networks would facilitate more effective end-to-end IP network architectures, but it remains a challenge. Network routing needs to be effectively addressed in the IoT environments of scarce computational and energy resources. Accordingly, the Internet Engineering Task Force (IETF) has specified the IPv6 Routing Protocol for Low Power and Lossy Network (RPL) to provide a bespoke IPv6-based routing framework for IoT networks. However, RPL comes with no Quality of Service (QoS) support which is an essential requirement for many IoT applications. The network research community has introduced a number of research proposals enhancing RPL with different QoS solutions. This paper presents a review of these proposed solutions and aims to establish a firm understanding of recent QoS developments for RPL and possible areas for future IoT routing research. The focus is on comprehending the protocol and networking properties that can affect QoS performance in RPL networks. Consideration is also given to different objective functions developed for addressing varying QoS aspects such as throughput, delay, and packet loss. RPL is also extended in a number of QoS solutions following different approaches at the MAC, network, and application layers. However, there is still a need for further developments to address effective QoS support, particularly for dynamic RPL networks. 相似文献
18.
针对当前图书馆在采取传统无人管理座位模式时,出现的座位有效使用率低,占座情况频发等突出问题,提出一种基于LoRa协议的智能图书馆座位管理系统的设计方案。该系统的感知层部署座位管理节点,LoRa网络采用星型拓扑结构,构建低功耗广域物联网智能图书馆座位管理系统。从系统总体设计、系统网络架构设计、系统功能设计、LoRa座位管理节点与LoRa基站软硬件设计以及通信协议设计等方面详细论述设计要点,并且对系统进行了功能及性能两方面的测试,结果表明,基于LoRa的智能图书馆座位管理系统相比传统的无人管理座位模式,座位有效使用率更高,读者寻找座位时间明显缩短,占座情况也得到改善,非常适合在图书馆的座位管理中推广应用。 相似文献
19.
目前在智能锁通信架构普遍采用WiFi、蓝牙、ZigBee等通信技术和IPv4协议,不能兼顾长距离传输和低功耗的需求,存在管理不便、安全性较低、IP地址匮乏等问题;针对这些问题,设计了一种基于IPv6和LoRa的智能门锁系统,系统由执行层、网络层、服务层和应用层四部分组成;门锁终端采用STM32L151CBU6微控器为主控制器,在云服务器上部署LoRa服务器和Java Web应用实现系统的管理和控制;测试表明,一个网关可覆盖一栋约11层楼的有效区域,一节1000 mAh电池可用1.8年,该系统拥有功耗低、通信距离长、安全性高等优点。 相似文献