嵌入式通信网络系统的抗毁性设计方法研究

嵌入式通信网络的运行环境复杂,降低了信息采集效率和通信网络协同控制任务性能。为了增强系统在复杂对抗环境下的协同性能,应提高系统的抗毁性。因此,采用LPC2290芯片作为微控制器,融合以太网模块、CAN模块、电源模块和相关外围接口模块,构建整个嵌入式通信网络系统。系统硬件电路结合子板和母板共同实现相关功能,提高系统的协同处理性能;采用基于Protocol_TCP协议的流套接子完成数据通信,增强通信系统的稳定性。依据嵌入式通信网络抗毁指标以及成本的最小化目标,设计网络抗毁性模型。将该抗毁性模型融入嵌入式通信网络自愈模型中,增强遭受攻击后网络的自愈能力,提高网络抗毁性能。实验结果表明,该设计系统具有较高的抗毁性,系统的吞吐量和平均时延性能较高。     

基于μclinux的EPA实时工业以太网延迟特性分析

EPA实时工业以太网作为一种实时控制网络,时延特性是影响其控制性能的关键因素,降低各种延迟是提高工业控制网络实时性的主要途径。文章在深入分析EPA实时调度策略的基础上,通过研究分析EPA网络中节点之间的通信过程,找出了影响网络延迟的关键因素,并给出了周期报文和非周期报文的排队等待延迟数学公式。最后通过计算和验证一个典型微网段的网络延迟,得出EPA网络所能达到的实时性指标。     

网络控制系统建模与控制

数据总线传输方案能够有效克服传统通信的弊端,但由于信息传输分时复用通信总线,系统时延不可避免。时延不但会降低网络控制系统的控制性能,而且还是引起系统不稳定的潜在因素。从网络时延这一问题出发,对网络控制系统的建模方法进行了分析研究,并基于此提出利用模糊控制来补偿系统时延影响。该方法通过模糊控制调节PID控制器输出,从而改善系统性能。最后通过仿真实例验证了上述方法的有效性。     

面向时间敏感网络的5G无线网增强技术研究

5G确定性网络是目前产业界正在积极推动的全新工业通信技术。为了逐步实现确定性传输,3GPP引入了时间敏感通信技术,与超可靠低时延通信技术相比,进一步在时延抖动和时间同步方面对5G网络进行了增强,从而实现端到端的时间敏感通信服务。介绍了时间敏感通信技术特点和标准进展,时间敏感通信技术以时间敏感网络与5G网络融合的网络架构为基础,通过精确时间同步机制提高时间同步精度,通过服务质量和调度增强机制降低业务时延、提高传输可靠性,通过以太网头压缩技术提高传输效率。     

软件定义FiWi网络中网络编码控制方法

针对传统FiWi(光纤无线混合接入)网络中网络编码控制过程中大量Gate、Report信息交换导致的网络信息复杂、编码时延增大等问题,设计了一种支持编码功能的软件定义FiWi网络架构和基于Openflow协议的网络编码控制方法。仿真结果表明,所提出的软件定义FiWi网络架构中的集中编码控制方法及其实现方案能够减少网络中控制信息数量,提高带宽利用率,有效降低数据传输时延并提高网络吞吐量。     

水下声传感器网络的同步与最优TDMA调度

水声信道的传输时延大、多径扩展严重、带宽受限等特点,极大地制约了水声通信系统的可靠性和有效性。实现水下传感器网络同步,并在同步的基础上设计调度协议是提高水下传感器网络性能的重要手段。在对水声网络同步机制深入研究的基础上,提出了一种基于时空特性的TDMA调度机制(ST-TDMA)。考虑传播时延抖动、同步误差和同步开销的影响,分析并求解了ST-TDMA的最优保护时间间隔。仿真结果表明,提出的ST-TDMA方案可以获得显著的网络吞吐量和端到端时延性能提升。     

基于网络编码的多信源组播通信系统

本文首先介绍网络编码理论的基本概念,回顾了近年来网络编码的研究动态。接着在使用NetFPGA开发平台的基础上,提出网络编码组播通信系统及其整体设计方案。由于本系统的主要功能是由硬件实现,所以和传统组播通信网络相比,具有时延小,没有了调度和排队时间,使得网络中链路负载更均衡,体现出了网络编码的优势。     

优先级控制轮询在变电站通信网络中的应用

变电站通信网络是变电站实现综合自动化的前提,变电站内部设备可划分成3个层次,其中第二层的数据和控制信息传送到与远方调度中心通信的站级PC机,该过程属于计算机通信网络的范畴,针对变电站通信网络的这个特点,将两级优先级控制轮询系统用在变电站通信网络中。提出了在站级PC通信接口(主节点)采用完全服务的轮询方式,第二层设备通信接口内部的数据缓冲区(子节点)采用门限服务的轮询方式的新模型。完全服务的优先级比门限服务的高,对新模型进行了仿真和理论计算,得出新系统的平均时延和平均排队队长与负载之间的关系、平均时延和平均排队队长与子节点数之间的关系,这些参数对于提高变电站通信网络的性能至关重要。     

6G通算融合网络架构

边缘计算在物理位置上部署在通信网络内,但是在逻辑上计算与通信拥有彼此独立的管控体系,协同是非实时的,在应对超低时延业务场景下用户信道状态、用户移动性等的动态变化时,存在技术挑战。因此,6G网络架构在设计之初,就需要原生的支持通信与计算的深度融合机制,基于此,提出了一种在无线网络内通信资源与分布式计算资源实时协同的计算面方案,来实现6G网络业务适配能力上的突破,提升综合资源能效。在终端和基站联合模型拆分推理场景下,通过仿真对比了控制面融合和管理面融合技术方案,验证了控制面融合方案能更好地应对终端空口连接带宽发生的变化,大幅降低业务时延抖动。     

工业以太网EPA实时性能测试中递交时间的确定

简述了工业以太网EPA及其实时性,分析了在EPA网络中存在通信调度和时间同步的原因,研究了递交时间的基本概念,并结合EPA网络给出了测量递交时间的模型和方法。测量中PC机作为控制台,控制测试流程、设置测试参数以及结果的显示,测试代理完成具体的测试任务。     

具有时延和丢包的不确定性NCS的稳定性

研究了同时具有网络时延和数据丢包的不确定网络化控制系统的稳定性.将数据丢失看成一种特殊的时延,利用动态反馈控制器设计提高系统的动态性能,得到了总时滞(包括传感器与控制器之间的时滞,控制器与执行器之间的时滞)的表达式,建立了不确定网络化控制系统模型.通过构造李亚普诺夫函数,采用线性矩阵不等式技巧,给出了系统稳定的判定定理.仿真结果表明了该方法的有效性.     

Analysis and determination of cooperative MAC strategies from throughput perspectives

In recent years, cooperative communication has been developed as a new communication strategy that incorporates a relay node to assist direct point-to-point transmission. By exploiting cooperative diversity, different types of techniques have been proposed to improve transmission reliability from the physical layer perspective. However, owing to the longer transmission time resulting from the cooperative schemes, there is no guarantee to enhance network throughput in view of the medium access control (MAC) performance. In this paper, system throughput of combined direct/cooperative communication is evaluated by exploiting the proposed analytical model based on the IEEE 802.11 MAC protocol. The feasibility of adopting either cooperative or direct communication is also studied in the analytical model. In terms of network throughput, whether to adopt cooperative schemes depends on the tradeoff between cooperative transmission delay and channel quality of direct communication. Moreover, two cooperative MAC protocols are proposed to determine the circumstances to activate cooperative communication according to the channel quality. The full-channel quality indicator based cooperative (FCC) MAC protocol is introduced to choose both the transmission scheme and the relay node according to the full channel quality information. However, the overhead caused by the FCC scheme can degrade the throughput performance as the number of available relays is significantly increased. Therefore, the bitwise competition based cooperative (BCC) MAC protocol is utilized to efficiently determine a feasible relay node for data transmission. Simulations are performed to validate the effectiveness of proposed analytical models and cooperative MAC protocols. It is observed that the proposed BCC scheme can outperform both the FCC protocol and conventional direct transmission with enhanced system throughput.     

New Predictive Control Scheme for Networked Control Systems

This paper is concerned with the design of networked control systems with random network-induced delay and data dropout. It presents a new control scheme, which is termed networked predictive control with optimal estimation. Based on Multirate Kalman Filtering, the measured data which are out of sequence or delayed can be used to improve the precision of estimation. The control prediction generator provides a set of future control predictions to make the closed-loop system achieve the desired control performance and the compensator removes the effects of the network transmission with time delay and data dropout. Simulation results are presented to illustrate the effectiveness of the control strategy via comparing with control schemes without any compensation for the network.     

Enhanced Resource Blocks Management in D2D based Communication for 5G Networks

D2D based communication holds a promising future for 5G networks as they are efficient and can yield high data rates, good signal to noise interference ratio, improved resource-block uploading time, minimized delay from one end to the other and conserved power for transmission. The traditional system of cellular type contains cell edge clients who need a larger resource blocks count as well as time to upload data. Hence the quality of service will be reduced. The relay scheme in the proposal for cooperative type D2D networks is pivoted on the value of channel gain as well as transmission link distance. For bringing down the resource blocks’ count as well as uploading time, the paper is proposing a capable scheme of selection of relays that employs communication of D2D in the situations of uplinking. To begin with, in a cell modeling is done. It contains D2D pairs of multiple types as well as cellular clients. Next, the analysis related to issues of allocating resources as well as control of power is done. In order to lessen the resource blocks as well as their uploading time, the paper in proposal suggests a better blocks management mechanism that uses D2D based communication. Simulated output infers that the method in the proposal is superior to the present methods as far as time to upload contents; resource blocks, SINR, throughput as well as rates of data and Energy Consumption are concerned. Added to that, the stated method conserves 43% of the Energy Consumption of the network clients and while doing that the time to upload the contents is not affected.

     

H-CRAN网络下联合拥塞控制和资源分配的网络切片动态资源调度策略

针对异构云无线接入网络(H-CRAN)网络下基于网络切片的在线无线资源动态优化问题,该文通过综合考虑业务接入控制、拥塞控制、资源分配和复用,建立一个以最大化网络平均和吞吐量为目标,受限于基站(BS)发射功率、系统稳定性、不同切片的服务质量(QoS)需求和资源分配等约束的随机优化模型,并进而提出了一种联合拥塞控制和资源分配的网络切片动态资源调度算法。该算法会在每个资源调度时隙内动态地为性能需求各异的网络切片中的用户分配资源。仿真结果表明,该文算法能在满足各切片用户QoS需求和维持网络稳定的基础上,提升网络整体吞吐量,并且还可通过调整控制参量的取值实现时延和吞吐量间的动态平衡。     

基于认知的协作系统中继分配算法

随着无线移动通信系统的飞速发展,无线通信网络能耗急剧增加,基于中继协作技术的绿色无线通信研究受到众多研究者的关注.针对基于认知的中继协作系统,提出了一种以最大主系统能效为目标的中继分配算法.该算法在不影响主系统性能基础上,对主系统请求次系统用户作为中继转发数据,且共享主用户频谱进行了简要介绍.算法中次系统通过最大权重匹配方法为主系统分配中继（次用户）,在满足主系统能效最大化的同时,实现了次系统与主系统的频谱共享.对算法进行仿真验证,提出的算法能获得较高的主系统能效,同时提高了整个系统的频谱利用率.     

An efficient cooperative technique for power-constrained multiuser wireless network

Cooperative communication plays an important role in wireless networks by improving network connectivity, spectrum efficiency, power, and communication reliability. Moreover, cooperative communication also facilitates the development of a well-organized approach in order to improve the quality of wireless terminals. Besides, it enables the utilisation of communication resources by allowing the nodes and pathways in a network to cooperate with one another via data transmissions. To control a wireless network, cooperative communication must manage its power to improve a network’s energy efficiency, capacity and reliability. When information is transmitted at a higher power, this decreases the lifespans of both the nodes and the network itself. Thus, controlling over the transmission of power is essential to obtain a sufficient level of bit-error-rate (BER) performance at the receiver. Relay nodes can improve system performance by reducing power consumption. Moreover, the decode-and-forward method is one of the best cooperative relay protocols that can be used to achieve better system performance in power constraints and BERs. In the present paper, system model containing source, destination and relay node is analysed. One cooperative scheme which including decode and forward is employed and investigated. At the experimental and simulation levels, the present paper showed that the power in the transmitters was observed and calculated in order to show the savings which are resulting from the use of relay nodes.     

基于特征根优化的无线网络控制系统故障检测滤波器设计

为提高无线传感器执行器网络(WSANs)的可靠性,本文提出了一种面向WSANs的故障检测滤波器的优化设计方法.针对无线网络固有的较大的数据包传输延迟,本文将该传输延迟对网络控制系统的影响建模为一种外部噪音,创造性地提出了基于特征根分解和扰动频率估计的优化算法,以滤除网络传输延迟导致的噪音.该方法只需在有限个频率点对目标函数进行优化,且避免了马尔科夫转移矩阵难以获得的难题.最后,通过MATLAB/NS2的混合仿真验证了该设计的有效性.     

一种异构网络多协议并行数据分发方法

跨技术通信迅猛发展推动着单一网络向异构无线网络的转变,该转变极大地提高异构无线设备(如Wi-Fi和ZigBee)的高效共存和协作,但也给异构无线网络中的数据分发问题带来了挑战。由于异构网络节点通信范围差异和低占空比节点周期性睡眠的特点,传统数据分发方法不能高效地利用信道资源而导致较低的分发效率。为了解决这些问题,该文提出一种适用于异构网络的并行数据分发方法。通过数据分发时延和能耗定义新的系统损失函数,并证明了损失函数的合理性,利用信标控制的延迟接收数据包的分发策略,从而实现对周期性睡眠的ZigBee网络进行高效数据分发。进一步地,该文根据动态规划的思想,推导出系统的整体能量损耗和时延的最优值。通过仿真实验证明,在考虑时延和能量损耗的前提下,该文的数据分发方法的性能优于传统的数据分发方法。     

Fractional delay compensated discrete-time SMC for networked control system

Time-varying network induced delay in the communication channel severely affects the performance of closed loop network control systems. In this paper, a novel idea of compensating the fractional time varying communication delay in the sliding surface is presented. The fractional time delay in the sensor to controller and controller to actuator channel is approximated using the Thiran approximation technique to design the sliding surface. A discrete-time sliding mode control law is derived using the proposed surface that compensates fractional time delay in sensor to controller and controller to actuator channels for uncertain network control systems. The sufficient condition for closed loop stability of the system is derived using the Lyapunov function. The efficacy of the proposed strategy is supported by the simulation results.