Cross-Layer Design Based Optimized Link State Routing Protocol for Wireless Mesh Networks

A proactive routing protocol CL-OLSR （cross-layer based optimized link state routing） by using a brand-new routing metric CLM （cross-layer metric） is proposed. CL-OLSR takes into account four link quality impact factors in route calculation through the cross-layer operation mechanism： the node available bandwidth, the node load, the link delivery rate, and the link interference, and thus the effect of route selection is optimized greatly. The simulation results show that the proposed CL-OLSR protocol can not only improve the network throughput to a large extent, but also reduce the end-to-end delay, while achieving load balance route results.

CARINA:一种高效的解决IoT互操作性的应用层协议转换方案

为了解决物联网设备众多、协议众多,以及协议架构和应用场景不同引发的物联网设备互操作性问题,针对应用层使用广泛的HTTP等4种协议,提出了一种基于协议包解析和关键方法映射的高效可扩展的应用层协议转换方案。考虑到4种协议的基础架构、消息格式、通信模式以及应用场景具有较大差异,该方案通过对协议原始数据包进行解析和关键信息提取,然后统一以键值对的形式进行信息存储,解决了不同协议信息存储的统一性问题。通过构造关键方法映射表,将不同协议的方法进行映射,实现了不同协议之间的互联。实验结果表明,基于所提方案实现的协议转换系统能很好地完成4种协议之间的消息转换。相比同类型的Ponte方法,在相同实验条件下,所提方案的转换速度都优于Ponte,甚至在某些情况下表现出了将近10倍的速度差距,同时支持多出一倍的转换类型。实验结果验证了所提方法在可扩展性和转换时间等效率方面相比同类型的协议转换算法具有显著提升。

A Contention-Based MAC and Routing Protocol for Wireless Sensor Network

Advance development of wireless technologies and micro-sensor systems have enabled Wireless Sensor Network (WSN) to emerge as a leading solution in many crucial sensor-based applications. WSN deploys numerous resource-constrained sensor nodes which have limited power supply, memory and computation capability in a harsh environment. Inefficient routing strategy results in degraded network performance in terms of reliability, latency and energy efficiency. In this paper, a cross-layer design, Contention-based MAC and Routing protocol is proposed, termed Contention/SNIR-Based Forwarding (CSBF) protocol. CSBF utilizes the geographical information of sensor nodes to effectively guide the routing direction towards destination node, thereby enhancing reliability. Furthermore, Signal-to-Noise-plus-Interference Ratio (SNIR) metric is used as a routing parameter to guarantee high quality link for data transmission. A Contention-Winner Relay scheme is utilized to reduce the delays caused by the contention procedure. Energy efficiency is also improved by introducing sleep mode technique in CSBF. The simulation work is carried out via OMNeT++ network simulator. The performance of CSBF is compared with other existing routing protocols such as AODV and DSDV in terms of packet delivery ratio (PDR), average end-to-end (ETE) delay and energy consumption per packet. Simulation results highlight that CSBF outperforms AODV and DSDV protocols in respect of PDR and energy efficiency. CSBF also has the most consistent overall network performance.

基于信息熵与服务器识别的DoH流量检测

DNS over HTTPS(DoH)协议是一种针对域名系统(DNS)的最新改进方案,然而用户可使用第三方DoH服务规避内网原有的监管,所以异常流量检测方法不再适用于检测DoH流量。针对该问题提出了一种DTESI算法。首先,基于信息熵将DoH流量作为异常流量从全部网络流量中筛选出来;然后,利用DoH服务器与同一客户端建立TLS连接时响应方式总是相同的特性,用指纹识别检测客户端与DoH服务器之间的TLS协商,确定DoH服务器身份;最后,使用Top-K抽样算法选出一定时段内网络中前K台活跃主机着重进行流量检测,使算法能应用于中大型组织的网络。实验结果表明,针对发现的异常流量,DTESI算法检测出的DoH服务提供商准确率超过94%。在此基础上比较了在不同K值下的算法检测时间和对网络中全部DoH流量的检测覆盖率,结果表明合理选择K值可以提升算法的整体效能。

变电站站控层服务协议CMS的应用研究

为了实现变电站站控层通信核心技术MMS(制造报文规范)的国产替代,国家电网公司制定了变电站二次系统CMS(通信报文规范),但未给出具体应用实现方案。因此,为推动CMS协议的应用和变电站核心技术的自主可控研究,提出一种在自主可控新一代嵌入式保护装置上实现CMS协议应用的解决方案,阐述了方案具体的程序实现方法,包括编解码实现、通信结构实现、CMS与MMS兼容性应用以及通信安全等,通过服务一致性测试和代码健壮性测试验证了方案的可行性。方案已在自主可控新一代产品平台中得到应用。

基于Chiplet技术的高效协议数据传输方法

数据传输任务具有多样性和复杂性,导致传输效率无法得到保障,为保障传输效率,文章提出基于Chiplet技术的高效协议数据传输方法研究。在数据传输协议层设计阶段,采用优化后的高速串行计算机扩展总线标准(Peripheral Component Interconnect Express,PCIe)数据包格式,并采用滑动窗口协议控制流量,具体发送窗口和接收窗口的大小根据实际需求调整设置;在数据传输适配层设计阶段,在每个Chiplet中嵌入唯一的身份标识号码(Identity Document,ID),通过建立统一的接口映射表,构建发送端和接收端之间的匹配关系。测试结果表明,采用该传输方法不仅总传输带宽未受到传输环境配置的影响,而且传输效率较高。

基于三层网络架构的农企园区网构建与仿真实验

为了提升园区网络的稳定性,降低因网络单点故障带来的影响,利用计算机网络仿真平台构建基于多协议双机热备三层网络架构的农企园区网架构模型,并结合由可编程逻辑控制器、各类传感器和边缘计算网关组成的农业生产环境监测网络,通过仿真模型进行实时数据传输以验证模型的有效性、可靠性和容错性。实验结果表明该网络架构模型能够有效规避由汇聚层和核心层单点故障引发的网络中断,通过随机多次模拟网络单点设备故障,网络整体自愈平均时间为35.74s,能够保证农业生产环境数据传输的永续性,将虚拟仿真网络架构模型与实体农业生产环境监测网络相结合进行研究验证,大幅度提升模型的仿真程度和验证结果的准确性。

An MAC Layer Aware Pseudonym (MAP) Scheme for the Software Defined Internet of Vehicles

This paper proposes a cross-layer design to enhance the location privacy under a coordinated medium access control(MAC) protocol for the Internet of Vehicles(Io V). The channel and pseudonym resources are both essential for transmission efficiency and privacy preservation in the Io V. Nevertheless, the MAC protocol and pseudonym scheme are usually studied separately, in which a new MAC layer semantic linking attack could be carried out by analyzing the vehicles' transmission patterns even if they change pseudonyms simultaneously. This paper presents a hierarchical architecture named as the software defined Internet of Vehicles(SDIV). Facilitated by the architecture, a MAC layer aware pseudonym(MAP) scheme is proposed to resist the new attack. In the MAP, RSU clouds coordinate vehicles to change their transmission slots and pseudonyms simultaneously in the mix-zones by measuring the privacy level quantitatively. Security analysis and extensive simulations are conducted to show that the scheme provides reliable safety message broadcasting, improves the location privacy and network throughput in the Io V.

不断集成创新的HART通信协议

随着微处理器成本逐渐下降、现场仪表智能化程度逐渐上升,全数字化的、双向多变量的通信协议替代原有的4~20 mA模拟信号已成为发展趋势。介绍了可寻址远程传感器高速通道(HART)通信技术的特点及不断创新的应用。自开放式通信协议于1986年推出以来,不断对技术进行创新,除了继续增强4~20 mA的数字通信能力,更发展了WirelessHART、HART-互联网协议(IP)、HART-IP over Ethernet-高级物理层(APL)等全数字通信技术。目前,HART设备在全球安装数量超过4000万台。HART通信协议已成为全球智能仪表普遍使用的工业标准。

A survey on communication protocols and performance evaluations for Internet of Things

The Internet of Things (IoT) is a large-scale network of devices capable of sensing, data processing, and communicating with each other through different communication protocols. In today's technology ecosystem, IoT interacts with many application areas such as smart city, smart building, security, traffic, remote monitoring, health, energy, disaster, agriculture, industry. The IoT network in these scenarios comprises tiny devices, gateways, and cloud platforms. An IoT network is able to keep these fundamental components in transmission under many conditions with lightweight communication protocols taking into account the limited hardware features (memory, processor, energy, etc.) of tiny devices. These lightweight communication protocols affect the network traffic, reliability, bandwidth, and energy consumption of the IoT application. Therefore, determining the most proper communication protocol for application developers emerges as an important engineering problem. This paper presents a straightforward overview of the lightweight communication protocols, technological advancements in application layer for the IoT ecosystem. The survey then analyzes various recent lightweight communication protocols and reviews their strengths and limitations. In addition, the paper explains the experimental comparison of Constrained Applications Protocol (CoAP), Message Queuing Telemetry (MQTT), and WebSocket protocols, more convenient for tiny IoT devices. Finally, we discuss future research directions of communication protocols for IoT.

MAC-PHY Cross-Layer for High Channel Capacity of Multiple-Hop MIMO Relay System

For the high end-to-end channel capacity, the amplify-and-forward scheme multiple-hop MIMO relays system is considered. The distance between each transceiver is optimized to prevent some relays from being the bottleneck and guarantee the high end-to-end channel capacity. However, in some cases, the location of relays can’t be set at the desired location, the transmit power of each relay should be optimized. Additionally, in order to achieve the higher end-to-end channel capacity, the distance and the transmit power are optimized simultaneously. We propose the Markov Chain Monte Carlo method to optimize both the distance and the transmit power in complex propagation environments. Moreover, when the system has no control over transmission of each relay, the interference signal is presented and the performance of system is deteriorated. The general protocol of control transmission for each relay on the MAC layer is analyzed and compared to the Carrier Sense Multiple Access-Collision Avoidance protocol. According to the number of relays, the Mac layer protocol for the highest end-to-end channel capacity is changed. We also analyze the end-to-end channel capacity when the number of antennas and relays tends to infinity.

MILITARY MULTI-HOP ROUTING PROTOCOL

Military tactical network is one of the most important applications of ad hoc network. Currently the existing routing protocols are put forward based on the simple and universal network model which has the ability of multi-hop routing but cannot work efficiently in the special military applications. The narrow bandwidth and limited energy of the wireless network make general routing protocols seem to be more redundant. In order to satisfy military needs properly, this letter makes a detailed analysis of physical nodes and traffic distribution in military network, uses cross-layer design concept for reference, combines traffic characteristic of application layer with routing protocol design. It categorized routing problem as crucial routes and non-crucial routes which adopted separate maintenance methods. It not only realizes basic transmission function but also works efficiently. It is quite fit for military application.

基于MQTT协议的物联网岸电监控系统

目前港口岸电系统地域分布较广且供电运行数据无法及时掌握。针对这一问题,设计并开发一种基于MQTT协议的物联网岸电监控系统,利用前端数据采集装置对供电系统的供电运行参数、用户信息、电力信息、设备状态等数据进行实时采集,经过数据处理和封装打包后,采用移动4G模块将封装好的数据通过MQTT协议上传至云端服务器,数据传输采用MD5数据加密算法,实现前端数据采集设备和监控系统之间的可靠数据通信,实时监控岸电系统运行状态,同时利用手机App对岸电系统参数进行实时监控与参数修改,增强物联网岸电监控系统的灵活性和便捷性。

FRS:Replication Driver Layer-Based Data Replication System on FreeBSD

Data replication is a key way to design a disaster tolerance system. This paper presents a replication driver layer-based data replication system on FreeBSD （FRS）. The system is embedded into the replication device driver layer, does not depend on specific storage devices and logical volume manager, and can achieve replication on data block level. The design considerations and decisions in defining FRS are described in detail.

A Effective Method for Properties Access in MAC Layer of ZigBee

The attribute access methods of MAC layer in wireless communication network is researched. Aiming at conquering the problem of the shared ZigBee wireless channel resulting multi-channel device conflicts when using the data channel at the same time, therefore the protocol is improved and a method used to access the properties of ZigBee is proposed, and this method can be achieved to manage effectively for all the 29 properties MAC layer, save storage space and realize property maintenance and expansion.

基于LVDS总线的故障注入系统设计

针对现有故障注入器的故障注入速度低,无法与高速微处理器的处理速度相匹配的问题,设计了一种基于LVDS总线的故障注入系统,该系统通过LVDS总线收发数据,FPGA为编解码芯片,在Linux系统中构建函数模型,通过对底层芯片的控制,搭建与LINUX系统中函数模型对应的故障模型,能够实现物理层、电气层和协议层的故障模拟和注入功能。最后,通过故障注入实验,得出本故障注入系统的故障注入速度可达到144 MHz左右,验证了该系统功能的实用性与先进性。

试论网络协议分层的实例教学法

TCP/IP是典型的网络分层协议,但是因为TCP/IP的协议基本是处于相关操作系统的内核中,因此对于分层协议实际工作策略掌握起来难度较大。通过IP报文在Linux的内核中进行重组与分段过程,可以在相关应用层对分层协议进行定义,同时UDP在用户的状态下使用套接字能够将应用层的消息重组与分段实现。这个模拟既清楚展示IP重组与分段过程关键处理的活动,又将分层协议整个处理过程直观的呈现出来,适用于计算机网络协议相关教学活动效果比较好。文章就网络协议应用消息重组与分段场景进行分析,探讨分层协议栈的设计,进而模拟应用层消息程序与分段,探讨网络协议分层的实例教学。

Modeling and Simulation Study of Space Data Link Protocol

This research paper describes the design and implementation of the Consultative Committee for Space Data Systems (CCSDS) standards REF _Ref401069962 \r \h \* MERGEFORMAT [1] for Space Data Link Layer Protocol (SDLP). The primer focus is the telecommand (TC) part of the standard. The implementation of the standard was in the form of DLL functions using C++ programming language. The second objective of this paper was to use the DLL functions with OMNeT++ simulating environment to create a simulator in order to analyze the mean end-to-end Packet Delay, maximum achievable application layer throughput for a given fixed link capacity and normalized protocol overhead, defined as the total number of bytes transmitted on the link in a given period of time (e.g. per second) divided by the number of bytes of application data received at the application layer model data sink. In addition, the DLL was also integrated with Ground Support Equipment Operating System (GSEOS), a software system for space instruments and small spacecrafts especially suited for low budget missions. The SDLP is designed for rapid test system design and high flexibility for changing telemetry and command requirements. GSEOS can be seamlessly moved from EM/FM development (bench testing) to flight operations. It features the Python programming language as a configuration/scripting tool and can easily be extended to accommodate custom hardware interfaces. This paper also shows the results of the simulations and its analysis.

Modeling TCP Incast Issue in Data Center Networks and an Adaptive Application-Layer Solution

In data centers, the transmission control protocol(TCP) incast causes catastrophic goodput degradation to applications with a many-to-one traffic pattern. In this paper, we intend to tame incast at the receiver-side application. Towards this goal, we first develop an analytical model that formulates the incast probability as a function of connection variables and network environment settings. We combine the model with the optimization theory and derive some insights into minimizing the incast probability through tuning connection variables related to applications. Then,enlightened by the analytical results, we propose an adaptive application-layer solution to the TCP incast.The solution equally allocates advertised windows to concurrent connections, and dynamically adapts the number of concurrent connections to the varying conditions. Simulation results show that our solution consistently eludes incast and achieves high goodput in various scenarios including the ones with multiple bottleneck links and background TCP traffic.

基于EDA技术的常用串口通信总线接口逻辑设计

新兴技术发展对通信总线接口性能提出了更高的要求,再加之接口之间交互行为的剧增,常规通信总线接口资源占用率过高、传输速度过低等缺陷逐渐显现。为了改善上述情况,提出基于EDA技术的常用串口通信总线接口逻辑设计。引入EDA技术搭建接口逻辑设计框架,以此为基础,选取适当的实现器件——FPGA控制器,设计具体数字接口(RS 232接收模块、I2C接收模块与SPI接收模块),并设计接口协议层(CRC校验、NRZI解码及其去除位填充),通过上述过程完成了常用串口通信总线接口的逻辑设计。实验数据表明,所设计接口资源占用率数值范围为19.58%~30.12%,传输速率最大值为48 Mb/s,达到预期接口设计目标。