无线LoRa在全业务泛在电力物联网终端层的应用

国家电网公司提出的“全业务泛在电力物联网”是能源网和物联网的融合演进,是服务于广大用户的关键能源基础设施。随着电力物联网的战略兴起,输电线路在线监测采集节点和监测规模将骤增,采用何种技术体制建设现场通信网络,兼顾考虑长距离、低功耗、高可靠等多重因素至关重要。对无线LoRa技术特点及优势进行了研究,结合输电线路在线监测的应用场景及需求,提出基于无线LoRa的输电线路在线监测组网方案并对其进行了适应性分析,研究成果在该领域具有一定参考意义。     

LoRa调制技术及解调算法

LoRa是目前工业界大力推广的一种低功耗广域网技术（LPWAN）技术,但其中的核心调制技术专利由美国Semtech公司拥有,其技术细节没有被公开。基于此,针对LoRa的调制解调技术原理进行详细的数学描述,并给出了具体的调制解调算法。同时,对LoRa调制的性能进行了高斯白噪声信道及多径衰落信道下的仿真比较,仿真结果验证了LoRa调制技术在低速远距离通信场景中的优越性。     

基于LoRa无线扩频通信的水情监测与预警系统

为解决目前水情监测系统中存在通信距离受限、功耗大、成本高、无法泛组网的问题,提出了一种基于LoRa（Long Range）扩频技术的水情监测与预警系统。通过采用新型的LoRa无线扩频技术,使用无线传感器网络自适应占空比协议优化网络性能与功耗,并结合当前流行的微控芯片、传感器与阿里云物联网（Internet of Things,IoT）平台,构建了一套覆盖范围广、低功耗、低成本、组网灵活简单、能远距离通信、抗干扰能力强的水情远程监测与预警系统。系统设计完成后,在长江水域重庆段对系统进行了测试,验证了系统设计的可行性、组网通信的有效性以及远距离传输数据的特性,为水文水情数据的自动化远程监测提供了一种新的技术方案。     

基于直接数字频率合成的远距离散射通信方法

远距离(LoRa)散射通信(BC)不仅成本低、功耗低,而且通信距离远。但现存散射方案的系统组成复杂,且无法应用于实际工程。为此该文提出一种新的LoRa散射通信方法,采用直接数字频率合成(DDS)技术产生频率线性变化的方波作为LoRa散射调制信号,并据此首次展示了基于MCU的LoRa散射通信系统原型样机。实验结果表明,该方法能够在相距208 m的基站和接收端之间的任意位置实现低功耗LoRa散射通信,且兼容现有的商用LoRa射频芯片组。此外,该方法还适用于专用集成电路(ASIC)设计,可使LoRa散射IC有更高的鲁棒性、更低的成本和功耗。     

A reconfigurable upper audio band modem for data communication between mobile devices

For communicating short data sequences over small distances, the use of devices with conventional wireless radio frequency interfaces requires standardized hardware, dedicated infrastructure and appropriate Link/Network layer protocols. To address challenges associated with these requirements, a communication mechanism using devices which support simple audio interfaces (speakers and microphones) is proposed using the upper audio band (UAB) of frequencies (16–20 kHz). Devices with audio interfaces can be deployed in a personal area network for communicating at low data rates over small distances. Multi-tone FSK modulation is used for transmitting Reed–Solomon encoded data over the UAB. For peer-to-peer communication applications, a sensing mechanism is enabled on the receiving device to sense for empty time–frequency slots and schedule its data transmission at the appropriate times. A system prototype is developed using portable speakers and smartphones with sensitive microphones. The effective throughput of the modem is evaluated for different sensing durations and distances. Ad-hoc peer-to-peer networks can be enabled between mobile devices for communicating short data sequences based on the UAB modem.     

The Fiddle Factor: Social Binding Functions of Distractions

An attempt is made to identify a typology of “fiddles”—informal and formal devices used by individuals and groups to facilitate communication and adhesion. Fiddling is defined as minor diversionary activity which is not directly related to the primary purpose of the person or group in communication. Identified and described on the personal level is the “fidget fiddle”; in interpersonal communication, the “conversational fiddle” and the “ritual fiddle”; in larger groups, the “orchestral fiddle” and the “task fiddle.” The “strategic fiddle,” applied to both interpersonal and group communication, is discussed. Briefly mentioned are the “catalytic fiddle” and the “status fiddle.” The typology of fiddles in communication behavior is presented as suggestive and exploratory. Relationships of the fiddle factor with education, communication research and psychoanalytic research are discussed.     

LoRa在电子价签系统中的应用与实现

传统无线局域网组网方式存在通信距离近、功耗高等问题，不能满足大型超市电子价签系统的通信要求。为此，提出一种基于LoRa（Long Range）通信技术的电子价签系统设计方案。采用具备LoRa调制方式的SX1278芯片作为系统LoRa模块的主芯片，以STM32单片机作为网关和节点价签的主控MCU，采用星型拓扑结构组网，并通过对通信过程中信噪比和接收信号强度两个参数值进行融合计算来分析信道状态，以此实现对数据传输速率的自适应调整。经实验测试，该系统通过服务器可经LoRa无线网络稳定传输数据，最终对电子价签显示内容进行更改，并有效提高了通信距离和降低功耗，可满足大型超市的实际需求。     

Efficient PDA synchronization

Modern personal digital assistant (PDA) architectures often utilize a wholesale data transfer protocol known as "slow sync" for synchronizing PDAs with personal computers (PCs). This approach is markedly inefficient with respect to bandwidth usage, latency, and energy consumption since the PDA and PC typically share many common records. We propose, analyze, and implement a novel PDA synchronization scheme (CPIsync) predicated upon previous information-theoretic research. The salient property of this scheme is that its communication complexity depends on the number of differences between the PDA and PC, and is essentially independent of the overall number of records. Moreover, our implementation shows that the computational complexity and energy consumption of CPIsync is practical and that the-overall latency is typically much smaller than that of slow sync or alternative synchronization approaches based on Bloom (1970) filters. Thus, CPIsync has potential for significantly improving synchronization protocols for PDAs and, more generally, for heterogeneous networks of many machines.     

基于FPGA的ARINC429通讯系统的设计与实现

ARINC429通讯总线在现代飞行器中得到广泛应用,需要研制与ARINC429通讯相应的测试系统。为了实现飞行器多路ARINC429总线与测试系统外围部件互连（PCI）总线之间的数据通讯,在分析ARINC429通讯协议的基础上,利用现场可编程门阵列（FPGA）芯片实现了独立的四路接收两路发送的ARINC429数据通讯以及系统与上位机的PCI通讯。该系统收发数据灵活、可靠,与传统的DSP加PLX9054加FPGA方案相比,电路简单,板卡体积小,功耗低,解决了飞行器多路ARINC429与测试系统的双向通讯。     

A cross-layer multihop data delivery protocol with fairness guarantees for vehicular networks

In this paper, a new cross-layer communication protocol for vehicular Internet access along highways is introduced. The objective of the new Controlled Vehicular Internet Access (CVIA) protocol is to increase the end-to-end throughput while achieving fairness in bandwidth usage between road segments. To achieve this goal, the CVIA protocol eliminates contention in relaying packets over long distances. CVIA creates single-hop vehicle clusters and mitigates the hidden node problem by dividing the road into segments and controlling the active time of each segment. Using an analytical throughput estimation model, the protocol parameters are fine-tuned to provide fairness among road segments. Simulation results confirm that the proposed CVIA protocol provides higher throughput and better fairness in multihop data delivery in vehicular networks when compared with purely IEEE 802.11-based protocols.     

基于ZigBee的自愈组网与协议实现

ZigBee技术是一种低功耗、网络容量大、时延小且具有自组织自愈功能的无线通讯技术。利用ZigBee技术组建的网络是一种低数据传输速率的无线个域网。在简要阐述传感器网络节点的基本体系结构的基础上,介绍了基于CC2530的ZigBee传感器节点的硬件组成。主要是对多跳自组路由协议和网状网的自愈的研究,并在此硬件平台上进行组网,通过对生理信息数据的传递来进行检验。     

Application‐driven power management for mobile communication

In mobile computing, power is a limited resource. Like other devices, communication devices need to be properly managed to conserve energy. In this paper, we present the design and implementation of an innovative transport level protocol capable of significantly reducing the power usage of the communication device. The protocol achieves power savings by selectively choosing short periods of time to suspend communications and shut down the communication device. It manages the important task of queuing data for future delivery during periods of communication suspension, and decides when to restart communication. We also address the tradeoff between reducing power consumption and reducing delay for incoming data. We present results from experiments using our implementation of the protocol. These experiments measure the energy consumption for three simulated communication patterns as well as three trace‐based communication patterns and compare the effects of different suspension strategies. Our results show up to 83% savings in the energy consumed by the communication. For a high‐end laptop, this can translate to 6–9% savings in the energy consumed by the entire mobile computer. This can represent savings of up to 40% for current hand‐held PCs. The resulting delay introduced is small (0.4–3.1 s depending on the power management level). This revised version was published online in July 2006 with corrections to the Cover Date.     

基于空分复用的多信道机间紫外光通信定向MAC协议

为了弥补飞行编队任务分配情况和不同模式下紫外光定向通信存在耳聋问题的缺陷,采用一种基于空分复用的多信道机间紫外光通信定向信道接入协议,建立了机间紫外光通信网络模型。通过在紫外节点安装多个不同方向的紫外收发装置来实现多信道信息交换,并仿真验证了多信道通信使耳聋问题得到明显缓解,提高了网络吞吐量,降低了网络时延,使得网络性能显著改善。结果表明,多信道通信与单信道通信相比,网络吞吐量增加,平均时延减小,网络性能大幅度提高,并且采用三信道通信模式通信效果最佳。     

机会网络中基于摆渡节点与簇节点相互协作的路由机制

机会网络是一种不需要在源节点和目的节点之间存在完整路径,利用节点移动带来的相遇机会实现网络通信的延迟容忍自组织网络,它以“存储-携带-处理-转发”的模式进行.为实现互不相交簇间的信息传输,本文设计了一种带阈值的簇移动模型CMMT,并提出了一种基于摆渡（Ferry）节点与簇节点协作的路由算法（CBSW）.该算法减少了冗余的通信和存储开销,以及在Spray阶段簇节点没有遇到目的节点或摆渡节点,进入Wait阶段携带消息的节点采用直接分发方式只向目的节点传输等问题.仿真实验表明,CBSW算法能够增加传输成功率,减少网络开销和传输延迟.     

基于LoRa标准的MAC层协议研究

物联网技术的发展已经经历了很多年,但是目前大多数物联网的互联仍在依靠互联网和移动互联网,专用于物联网的网络协议缺失,这在一定程度上制约了物联网的大规模普及.以LoRa为代表的低功耗、远距离网络技术的出现,有效解决了物联网复杂组网和超高功耗的难题.针对物联网互联的相关技术进行了探讨,介绍了超窄带物联网技术及低功耗广域网,并主要研究了LoRa技术的MAC层协议,详细论述了该协议的实现过程.     

Performance evaluation and application of channel offset schemes inindoor channel assignments

We deal with channel offset schemes and their application in three-dimensional (3-D) frequency reuse environments with ideal cubic microcells. Formulas are derived to calculate channel reuse distances (CRDs) and interchannel usage distances (IUDs) for a given offset degree. For an indoor personal communication network (PCN), an algorithm is proposed for fixed channel assignment with channel offset. The spectral efficiency of channel offset schemes is discussed and the results show that compared to the channel offsetless scheme, channel offset schemes make more efficient use of limited spectrum resources     

LoRa-Based WSNs Construction and Low-Power Data Collection Strategy for Wetland Environmental Monitoring

The wetland that known as "the kidney of the earth" is an ecological system with many resources. Monitoring of wetland environment includes the monitoring of water quality, air and soil. The parameters of temperature, pH value, turbidity, dissolved oxygen (DO), water level, conductivity of water, illuminance, PM2.5, harmful gas, and soil moisture is particularly important for the survival of animals in wetland. Real-time monitoring wetland environment is conducive to understanding the causes and trends of environmental change in the whole region, so as to make environmental change emergency strategies timely. The author introduces a real-time monitoring system based on Multi-sensor Combination Module (MSCM) and LoRa. This system has two types of MSCM, one is for water and the other is for air. The MSCM for water consists of six sensors, such as water temperature sensor, pH sensor, turbidity sensor, dissolved oxygen sensor, conductivity sensor, and water level sensor, and stm32 core processor, which has the advantages of low power consumption and high speed. The data collection node uploads the collected data to the base station through a LoRa module with low power consumption, high speed and wide coverage. The base station and the collection node are connected in a star. The LoRaWan protocol is used to realize the communication between acquisition nodes and sink. In the case of code rate is 4/5, bandwidth is 500 kHz and spreading factor is 12, the effective throughput of the system can reach 1172 bps. At the same time, a data fusion algorithm based on fuzzy decision is designed for data processing on the acquisition nodes to reduce the amount of uploaded data, reduce power consumption and improve network throughput. Experiments show that the system has strong stability, flexible networking, low power consumption, long communication distance, and is suitable for wetland environmental monitoring.

     

个人通信系统中的一种移动用户登记认证协议

假冒和窃听攻击是无线通信面临的主要威胁。在个人通信系统中,为了对无线链路提供安全保护,必须对链路上所传送的数据/话音进行加密,而且在用户与服务网络之间必须进行相互认证。近年来,人们在不同的移动通信网络(如GSM,IS-41,CDPD,Wireless LAN等)中提出了许多安全协议。然而,这些协议在个人通信环境中应用时存在不同的弱点。本文基于个人通信系统的双钥保密与认证模型,设计了用户位置登记认证协议;并采用BAN认证逻辑对协议的安全性进行了形式化证明,也对协议的计算复杂性进行了定性分析。分析表明,所提出的协议与现有的协议相比具有许多新的安全特性。     

FUCA: Fuzzy‐based unequal clustering algorithm to prolong the lifetime of wireless sensor networks

Wireless sensor network comprises billions of nodes that work collaboratively, gather data, and transmit to the sink. “Energy hole” or “hotspot” problem is a phenomenon in which nodes near to the sink die prematurely, which causes the network partition. This is because of the imbalance of the consumption of energy by the nodes in wireless sensor networks. This decreases the network's lifetime. Unequal clustering is a technique to cope up with this issue. In this paper, an algorithm, “fuzzy‐based unequal clustering algorithm,” is proposed to prolong the lifetime of the network. This protocol forms unequal clusters. This is to balance the energy consumption. Cluster head selection is done through fuzzy logic approach. Input variables are the distance to base station, residual energy, and density. Competition radius and rank are the two output fuzzy variables. Mamdani method is employed for fuzzy inference. The protocol is compared with well‐known algorithms, like low‐energy adaptive clustering hierarchy, energy‐aware unequal clustering fuzzy, multi‐objective fuzzy clustering algorithm, and fuzzy‐based unequal clustering under different network scenarios. In all the scenarios, the proposed protocol performs better. It extends the lifetime of the network as compared with its counterparts.     

基于LoRa的无线电气象参数集成监测系统设计

通过无线电气象参数可以获得影响无线电波变化的气象参数变化规律.为研究各种气象变化对无线电波的影响,对无线电气象参数进行准确测量和数据的远程传输与管理,提出了一种基于LoRa的无线电气象参数集成监测系统.系统以LoRa技术为核心进行自组网设计,采用北斗短报文技术进行远距离通信.气象监测节点采用低功耗的STM32微处理器,通过移植uCOS-Ⅲ实时操作系统来实现多传感器集成模块的多任务调度,远程终端采用Qt设计了配套的上位机软件进行无线电气象参数实时处理分析.实测结果表明,在通信距离小于2 km时,LoRa数据传输丢包率小于10%,上位机软件可准确显示并存储无线电气象数据.系统具有稳定可靠、集成度高、组网便捷、通信距离远等特点,可以实现对复杂环境中无线电气象参数的实时采集和远程管理,这为气象学研究提供了有效的无线电气象参数数据.