双目视觉辅助PDR的组合导航定位方法

为提高室内定位系统精度和跟踪性能以及适应复杂环境,将行人航迹推算（Pedestrian Dead Reckoning,PDR）与双目视觉组合,提出一种双目视觉辅助PDR的组合导航定位方法 .该方法通过选取或布置地标建立了地标位置数据表;基于轻量化目标检测实现了对地标实时双目测距,保证定位的实时性;利用PDR位置信息得到检出地标类别对应坐标,基于因子图的协同定位和误差估计算法将双目视觉与PDR有效融合,提高了定位精度并抑制PDR累计误差,同时对PDR中航向和单参数模型中单位转换常数进行误差补偿,提高PDR定位精度.实验结果表明,在地标纹理清晰且分布合理情况下,该方法能有效解决室内复杂环境下单一PDR累积误差问题,此外,对航向和单位转换常数实时补偿可提高组合定位系统的定位精度和稳定性.     

基于FOA改进MCB算法的无线传感网络节点定位精度分析

为了提高无线传感网络（WSN）定位精度，应用果蝇优化算法（fruit fly optimization algorithm,FOA）-蒙特卡洛锚盒（Monte Carlo anchor box,MCB）算法（简称“FOA改进MCB算法”）对WSN中移动节点定位，分析了移动速度和锚节点数量对定位精度的影响。研究结果表明：相较于MCB算法，FOA改进MCB算法具有更优的定位精度；定位误差随着节点移动速度的增加而增大；随着锚节点数量的增加，定位误差表现为降低的趋势。该研究对提高无线传感网络节点定位精度具有重要意义，易于实现推广。     

基于RSSI测距的WSN定位网络监测系统设计

文章分析了基于RSSI测距的WSN网络定位技术,以ti CC2530芯片为核心设计定位节点,实现了一套适用于各类室内密闭环境的WSN定位网络。针对RSSI测距精度有限、易受环境干扰的问题,文章设计了一套测距模型参数校准流程,用以降低RSSI测距误差,提高系统定位精度,并开发了上位机操作程序,便于用户实时监测网络运行情况。     

无线传感器网络混合定位技术研究

在大规模复杂无线传感器网络中往往采用多种节点定位技术,在此结合现有无线传感器定位技术的现状,提出了一种混合定位技术以实现不同定位方法之间的互补。一方面利用RSSI定位弥补TDOA定位覆盖范围小的缺点;另一方面将测距信息引入到非测距定位DV—Hop算法中,用RSSI测距模型来提高DV-Hop算法中定位节点与信标节点间有效距离的精度。实验结果表明,该混合定位技术实现了TDOA,RSSI以及DV-HOP等定位技术的融合,有效地提高了复杂大规模无线传感器网络的节点定位精度。     

室内Wi-Fi/PDR自适应鲁棒卡尔曼滤波融合定位方法

针对室内复杂环境下信道状态信息的动态性问题,本文提出了一种面向室内Wi-Fi/行人航迹推算（Pedestrian Dead Reckoning,PDR）融合定位的自适应鲁棒卡尔曼滤波方法.该方法利用自适应鲁棒卡尔曼滤波将Wi-Fi传播模型与PDR定位信息进行多重融合,推算用户的最优估计位置.同时,基于滤波反馈机制,通过融合定位结果对加权最小二乘法中的路径损耗指数和滤波模型中的观测协方差进行动态修正,保证Wi-Fi传播模型接近于真实室内环境.实验结果表明,该方法能够有效解决室内复杂环境下单一Wi-Fi定位精度低和PDR累积误差的问题,此外,路径损耗指数和观测协方差的实时修正可以提高融合定位系统的定位精度和稳定性.     

基于 RSSI 的无线传感器网络节点定位算法研究

节点位置信息是无线传感器网络应用的基础。基于RSSI（Receive Signal Strength Indicator）的测距技术因其低成本和低复杂度的优点而被广泛用于无线传感器网络的定位技术中。介绍了RSSI信号传输模型,在介绍无线传感器网络定位基本原理的基础上,分析了影响定位精度的因素。综述了近几年提出的无线传感器网络中基于RSSI的节点定位算法及其改进算法,现有基于RSSI定位算法的改进算法主要从测距精度改进、定位精度改进或误差修正改进等方面进行。最后,指出了基于RSSI的无线传感器网络节点定位算法的不足,并进行展望。     

基于RSSI测距信号衰减因子的WSN定位算法研究

在无线传感器网络中定位技术是运用广泛的重要技术,在基于距离的定位技术中,测距精度在很大程度上决定了定位精度.传统的RSSI测距法存在路径损失模型复杂、环境变化引起信号严重震荡而产生测距误差等不足.针对以上问题,本文提出利用锚节点测距信号衰减因子的RSSI测距法,该测距法无需建立路径损失模型,同时,信号衰减因子与RSSI测距有很强的关联性,减少了因其他因素引起的信号强度值震荡而带来的测距误差,具有很好的环境适应能力.     

基于TOA/TDOA超宽带无线定位算法的改进

在充分研究了超宽带无线传输技术特性的基础上,对超宽带无线定位的原理进行了探讨.首先详细介绍了超宽带测距和定位的原理,对超宽带定位的精度进行了仿真分析.然后,针对超宽带Ad Hoc网络实际应用中节点数目比较多的情况,引入了节点的相关性来提高超宽带的定位精度,并进行了仿真分析.仿真结果显示了此算法在网络节点数比较多的情况下对定位精度有比较好的提高效果.     

蜂窝移动通信定位系统的关键技术

移动电话定位的设计要求定位跟踪系统设计必须考虑的主要因素有：定位精度：这是衡量系统性能的重要指标。由于无线电波传播环境复杂和不稳定，系统的复杂度和实现难度将随定位精度的提高而呈指数增长。由于不同的定位技术所能够达到的定位精度不同，所以定位精度也将决定能够选择的定位技术范围。美国FCC提出的以67%概率实现125米精度的定位要求已经被业界所接受并成为民用蜂窝定位的精度标准。目前，国外主要公司对各种移动通信系统（AMPS、GSM、CDMA）的测试结果均证明了这一精度的可行性。位置信息更新速率：在实现用户定位之后，…     

WSN中基于稀疏观测和异步传输的分布式实时定位算法

针对无线传感器网络（WSN）中现有集中式多维标度（MDS-MAP）节点定位算法在定位精度和分布式方面的不足,提出一种基于稀疏观测和异步传输的分布式实时定位算法。首先在传统MDS-MAP算法中融入稀疏观测机制,使其能够更好地符合实际观测场景;然后提出一种异步传输序列,使节点能够分布式计算距离观测,并通过分布式计算结果给出位置估计;最后通过提出的位置估计精化操作减小估计误差,最终实现节点的精确定位。实验结果表明,该算法具有较高的定位精度。     

Providing deterministic quality-of-service guarantees on WDM optical networks

A major challenge in the design of future generation high-speed networks is the provision of guaranteed quality-of-service (QoS) for a wide variety of multimedia applications. In this paper we investigate the problem of providing QoS guarantees to real-time variable length messages (e.g., IP packets) in wavelength division multiplexing (WDM) optical networks. In particular, we propose a systematic mechanism comprised of admission control, traffic regulation, and message scheduling that provide guaranteed performance service for real-time application streams made up of variable-length messages. We formulate an analytical model based on the theory of max-plus algebra to evaluate the deterministic bounded message delay in a WDM network environment using our proposed QoS guarantee mechanism to determine the "schedulability conditions" of multimedia application streams, We also conduct a series of discrete-event and trace-driven simulations to verify the accuracy of the analytical model. The simulation results demonstrate that the analytic delay bound we obtained for our WDM optical network is valid and accurate.     

基于遗传算法的时延受限代价最小组播路由选择方法

目前多媒体业务的涌现对网络提出了更高的要求。希望既能满足实时性，又能够高效地利用网络资源。本文提出了一种基于遗传算法的组播路由选择方法，该方法在满足时延限制条件的基础上寻找代价最小的组播树。实验表明，该算法收敛速度快，可靠性高，能够满足多媒体网络对实时性的要求。     

基于自注意力机制的干扰信号检测识别

为了解决卫星通信系统在对抗电磁环境中的干扰实时检测识别问题,提出了一种基于自注意力(Self-attention,SA)机制的高效轻量化网络模型。通过采用DenseNet加速对原始IQ信号的特征提取,并引入自注意力模块代替参数量较大的多重卷积层,实现对卫星通信系统中常见的干扰样式进行分类识别。仿真结果表明,在识别准确率方面达到常规的神经网络模型和算法性能水平的条件下,所提模型在网络复杂度和运算时延方面得到有效压缩。     

α-channel: a network framework to support applicationreal-time performance guarantees

A framework to support performance requirements for real-time applications in packet-switched networks is proposed. This framework is based on a network-level abstraction called α-channel. An α channel represents a simplex end-to-end communication channel characterized by a set of application-specific real-time performance values. Applications treat the α-channel as an end-to-end abstraction and specify their required performance characteristics in terms of the maximum end-to-end packet delay, the maximum number of packets that can be sent within that delay, and the on-time reliability. Based on specified parameters, the network verifies that it can guarantee the performance of the channel under any conditions baring hardware failures. The approach the framework uses to verify the feasibility of accepting an α-channel and the characteristics of the run-time environment to guarantee the applications' performance requirements are described. The results of a simulation experiment implementing the basic functionalities of the proposed scheme are also presented     

Optimal trajectory determination of a single moving beacon for efficient localization in a mobile ad-hoc network

An ad hoc network of small robots (sensor nodes) adjusting their positions to establish network connectivity would be able to provide a communication infrastructure in an urban battlefield environment. A sensor node would be capable of moving to a particular position to establish network connectivity, provided it knows its current position, positions of other sensor nodes and the radio propagation characteristics of the sensor area.In this paper, we present a pseudo formation control based trajectory algorithm to determine the optimal trajectory of a moving beacon used in localization of the sensor nodes in real-time. The trajectory and the frequency of transmission of the GPS based position information of the moving beacon influences the accuracy of localization and the power consumed by the beacon to localize. Localization accuracy and reduction in the number of position information messages can be achieved, in real-time, by determining the optimal position from where the beacon should transmit its next position information. This will decrease the time required to localize, and power consumed by the beacon in comparison to random or predetermined trajectories.We first show that optimal position determination is a pseudo formation control problem. Next, we show the pseudo formation control problem formulated as an unconstrained optimization problem under the free space propagation model. We further present the modeling of the beacon incorporating the trajectory algorithm based on the pseudo formation control in a discrete event simulator. Simulation results, comparing the performance of localization with pseudo formation control based trajectory against random waypoint and predetermined trajectories for the beacon are presented. The simulation results show that the localization accuracy is significantly improved along with reduction in the number of position information messages transmitted when the beacon traverses along the pseudo formation control based trajectory.     

面向实时感知的车联网业务监控应用研究

基于车联网的数据实时采集和人车交互的基础是可靠的网络接入服务和良好的通信保证,为此文中研究了车联网中车辆接入车联网的通信可靠性保证策略和网络质量优化方法。首先,由于车辆节点的通信不稳定性和动态性,研究了动态的车联网网络质量评估方案。其次,这项工作研究了基于车辆轨迹的对车辆接入网络的数据交互时间预测算法,以应对车联网不稳定的网络拓扑和高断开率。最后,提出了一种实时通信质量感知的网络接入策略,用于为道路上的车辆提供车联网服务。仿真结果证明了该方案在不同的通信距离下具有相对较高的网络接入成功率和较好的通信质量。     

A framework for deterministic delay guarantee in OBS networks

In OBS networks, the delay of control packets in the switch control unit (SCU) of core nodes influences burst loss performance in the optical switching and should be constrained. Furthermore, the end-to-end (E2E) delay requirements of premium services need queueing delay guarantee in network nodes throughout the transmission path. For this purpose, a framework for deterministic delay guarantee is proposed in this article. It incorporates the deterministic delay model in the ingress edge node as well as in the SCUs of core nodes. On this basis, the configuration of the assembler and the offset time is addressed by means of an optimization problem under the delay constraints. Scenario studies are carried out with reference to realistic transport network topologies. Compared to statistical delay models in the literature, the deterministic model has advantages in rendering robust absolute delay guarantee for individual FEC flows, which is especially appreciated in the provisioning of premium services. By performance evaluation in comparison with the statistical models, it is shown that the adopted deterministic delay models lead to practical delay bounds in a magnitude that is close to the delay estimations by stochastic analysis.     

通信IP网BFD应用的研究

通信IP网作为实时业务传输载体,要求能够对相邻系统之间通信故障进行快速检测,在出现故障时可以快速切换到备份链路,以保证实时数据不间断传输。在研究BFD协议原理的基础上,根据通信IP网运行中出现的问题,应用BFD双向快速检测功能,实现了VRRP的Master/Backup状态毫秒级切换,并利用BFD会话检测静态路由所在链路的状态,实现一跳和多跳的静态路由自动切换,提高了通信IP网的可靠性。     

基于Profibus PLC控制系统中的网络技术

随着生产对自动化控制要求的不断提高,控制系统中各设备间需要高实时性、高可靠性的通信。在介绍PLC控制系统中的通信与网络技术、Profibus现场总线技术的基础上,针对PLC控制系统特点,将Profibus现场总线技术应用到PLC控制系统中,大大提高了数据传输的速度、准确性和可靠性,提高了控制质量。