针对车地传输TCP协议优化的TTI-RTT拥塞控制算法

为适应铁路5G专用移动通信系统动态易变的网络环境,解决现有算法中存在的吞吐量减少、传输时延增加、检测数据车地传输可靠性难以保证的问题,在分析传输控制协议(TCP)传输拥塞控制过程,以及对比TCP-Reno,TCP-Vegas和TCP-Westwood 3种基础拥塞控制算法存在问题的基础上,提出一种联合传输时间间隔(TTI)和往返时延(RTT)的拥塞控制算法——TTI-RTT算法,即将RTT的成对比较测试统计量和网络当前拥塞因子联合起来作为网络拥塞判断标准,根据反映网络拥塞程度的拥塞因子动态调节加性和乘性因子,并在传输控制协议拥塞控制的不同条件下灵活调整传输时间间隔。采用NS-3仿真软件,构建考虑高速铁路5G-R无线信道误码影响的点对点通信网络拓扑结构,对TTI-RTT拥塞控制算法进行仿真验证,并与3种基础算法进行性能比较。结果表明:不同丢包率下所提算法的平均吞吐量均保持在9 Mb·s^(-1)以上,较基础算法中吞吐量最高且最稳定的TCP-Reno算法增加了约5.9%,且实时吞吐量稳定性具有显著改善。

Improving Throughput of Transmission Control Protocol Using Cross LayerApproach

Most of the internet users connect through wireless networks. Majorpart of internet traffic is carried by Transmission Control Protocol (TCP). It hassome design constraints while operated across wireless networks. TCP is the traditional predominant protocol designed for wired networks. To control congestionin the network, TCP used acknowledgment to delivery of packets by the end host.In wired network, packet loss signals congestion in the network. But rather inwireless networks, loss is mainly because of the wireless characteristics such asfading, signal strength etc. When a packet travels across wired and wireless networks, TCP congestion control theory faces problem during handshake betweenthem. This paper focuses on finding this misinterpretation of the losses using crosslayer approach. This paper focuses on increasing bandwidth usage by improvingTCP throughput in wireless environments using cross layer approach and hencenamed the proposed system as CRLTCP. TCP misinterprets wireless loss as congestion loss and unnecessarily reduces congestion window size. Using the signalstrength and frame error rate, the type of loss is identified and accordingly theresponse of TCP is modified. The results show that there is a significant improvement in the throughput of proposed TCP upon which bandwidth usage isincreased.

A Stream Control Transmission Protocol Based OAM System of 3G Cellular Network

OAM (Operations, Administration and Maintenance) system is a very impo rtant component of 3G cellular network. In order to acquire overall managemen t, fast response and steady operation, an SCTP (Stream Control Transmission Prot ocol) based OAM, i.e., SOAM system was proposed. SOAM implements new characters of SCTP such as multi-stream, enforced SACK and heartbeat mechanism on its tran sport layer. These characters help SOAM decrease the message transmission delay and accelerate the link failure detection. Besides, a new component named SOAM agent was introduced to improve the operation efficiency of SOAM. The experim ental results prove the proposed SOAM system achieves better performance on sign aling transmission compared with conventional TCP based OAM system.

基于TCP/IP协议与关联规则的电力监控系统多线程通信方法

电力监控系统环境中存在过多噪声因素干扰,导致通信效率和质量低。为此,提出一种基于传输控制协议/网际协议(transmission control protocol/internet protocol,TCP/IP)与关联规则的多线程通信算法。将背景噪声看作电力监控信号的突变现象,查找回应突变函数的信号值,利用谐波分离算法,去除背景噪声。根据不同线程的传输特点,采用TCP/IP协议建立通信程序包,分别设置句柄、终止、挂起以及执行函数,为不同线程的通信数据,匹配不同的通信协议。试验结果证明:对电力监控系统源设备的传输信号多线程通信时,通信信号波频变化最为平稳,在0~2000 s的采样区间内,未出现传输为0现象;对背景噪声去噪后,波形相比原始信号变化明显较为稳定,没有出现过高或过低的幅值变化。所提方法通信信号表达平稳、效率较高,对原始信号的保留效果较好,去噪能力很强。

基于LwIP和Modbus TCP协议的网络控制器设计

为了实现对终端设备的网络远程控制和监测,该文设计了一款基于LwIP和Modbus TCP协议的网络控制器。该控制器以STM32F107RCT6和LAN9303芯片为核心,设计出了网络通信电路、网口电路、A/D采样电路、光耦隔离电路和IO口电路。软件设计主要完成了LwIP协议栈的移植、Modbus TCP协议程序和其他控制程序的编写。经过测试,所设计的网络控制器在对设备进行远程控制和监测时具有数据传输可靠、通讯稳定和实时性好的优点,能满足工厂使用。

BIFURCATIONS AND CHAOS CONTROL IN TCP-RED SYSTEM

Objective Analyzing the nonlinear dynamics of the TCP-RED congestion control system is of great importance. This study will help investigate the loss of stability in Internet and design a proper method for controlling bifurcation and chaos in such system. Methods Based on bifurcation diagram, the effect of parameter on system performance is discussed. By using the state feedback and parameter variation strategy, a simple real time control method is proposed to modify the existing RED scheme. Results With our control method, the parametric sensitivity of RED mechanism is attenuated. Moreover, a sufficient condition on the robust stability of the system is also derived to adjust the parameters in TCP-RED system. Conclusion The proposed method has the advantages of simple implementation and unnecessary knowledge of the exact system.

A Dual-Channel Secure Transmission Scheme for Internet-Based Networked Control Systems

Two significant issues in Internet-based networked control systems （ INCSs）, transport performance of different protocols and security breach from Internet side, are investigated. First, for improving the performance of data transmission, user datagram protocol （UDP） is adopted as the main stand for controllers and plants using INCSs. Second, a dual-channel secure transmission scheme （DCSTS）based on data transmission characteristics of INCSs is proposed, in which a raw UDP channel and a secure TCP （transmission control protocol） connection making use of SSL/TLS （secure sockets layer/transport layer security） are included. Further, a networked control protocol （NCP） at application layer for supporting DCSTS between the controllers and plants in INCSs is designed, and it also aims at providing a universal communication mechanism for interoperability of devices among the networked control laboratories in Beijing Institute of Technology of China, Central South University of China and Tokyo University of Technology of Japan. By means of a networked single-degree-of-free- dom robot arm, an INCS under the new protocol and security environment is created. Compared with systems such as IPSec or SSL/TLS, which may cause more than 91% network throughput deduction, the new DCSTS protocol may yield results ten times better, being just 5.67%.

TCP Window Based Congestion Control -Slow-Start Approach

Transmission control protocol (TCP) has undergone several transformations. Several proposals have been put forward to change the mechanisms of TCP congestion control to improve its performance. A line of research tends to reduce speed in the face of congestion thereby penalizing itself. In this group are the window based congestion control algorithms that use the size of congestion window to determine transmission speed. The two main algorithm of window based congestion control are the congestion avoidance and the slow start. The aim of this study is to survey the various modifications of window based congestion control. Much work has been done on congestion avoidance hence specific attention is placed on the slow start in order to motivate a new direction of research in network utility maximization. Mathematical modeling of the internet is discussed and proposals to improve TCP startup were reviewed. There are three lines of research on the improvement of slow start. A group uses the estimation of certain parameters to determine initial speed. The second group uses bandwidth estimation while the last group uses explicit request for network assistance to determine initial startup speed. The problems of each proposal are analyzed and a multiple startup for TCP is proposed. Multiple startups for TCP specify that startup speed is selectable from an n-arry set of algorithms. We then introduced the e-speed start which uses the prevailing network condition to determine a suitable starting speed.

TCP/AWM网络系统的事件触发预设性能拥塞控制

研究了具有非响应用户数据报协议流干扰的TCP/AWM网络系统的跟踪控制问题.针对网络拥塞控制系统,给出了一种改进的网络模型.将预设性能控制和事件触发机制相结合,提出了一种新的AWM拥塞控制算法.利用改进的边界性能函数限制TCP/AWM网络系统的队列跟踪误差,提高了闭环系统的暂态和稳态性能,保证了所有闭环信号都是有界的.此外,采用基于一位信号传输的事件触发控制协议,当控制信号更新时,仅通过一个二进制信号(0或1)传输信息.与传统的事件触发控制协议相比,不仅考虑了有限的带宽,而且考虑了网络传输的成本以及安全性问题.最后,通过仿真验证和分析,证明了所提方法的可行性和优越性.

AN ENHANCEMENT SCHEME OF TCP PROTOCOL IN MOBILE AD HOC NETWORKS:MME-TCP

Transmission Control Protocol (TCP) optimization in Mobile Ad hoc NETworks (MANETs) is a challenging issue because of some unique characteristics of MANETs. In this paper,a new end-to-end mechanism based on multiple metrics measurement is proposed to improve TCP performance in MANETs. Multi-metric Measurement based Enhancement of TCP (MME-TCP) designs the metrics and the identification algorithm according to the characteristics of MANETs and the experiment results. Furthermore,these metrics are measured at the sender node to reduce the overhead of control information over networks. Simulation results show that MME-TCP mechanism achieves a significant performance improvement over standard TCP in MANETs.

基于LSTM的Modbus TCP协议模糊测试优化方法

针对工控系统传输协议模糊测试的路径爆炸和约束求解问题,提出一种基于长短时记忆(LSTM)网络的Modbus TCP协议模糊测试优化方法,挖掘出两种工控协议漏洞,分别为非法写入漏洞和数据值边界漏洞。抓取模糊测试数据包形成数据集,并根据状态码将其分为正常用例、异常用例和无效用例三种,通过LSTM识别出无效用例并剔除,提高漏洞挖掘效率。实验结果表明,LSTM识别模糊测试数据集的准确率达到93.87%,经过LSTM优化后的测试用例通过率从30.75%提升至33.99%。

基于Modbus/TCP的无线通信网络安全加密控制系统设计

为控制明文加密时长、密文响应时长之间的相对时延量,实现无线网络对于通信数据的安全性加密,设计基于Modbus/TCP的无线通信网络安全加密控制系统;匹配PowerPC嵌入式架构与复位通信控制电路之间的实时连接关系,借助微处理器子模块,确定宿主机与客户机对通信网络的贡献价值,再按照Modbus/TCP协议连接标准,整合交换区中已存储的通信数据文本,完成无线通信网络安全加密控制系统硬件设计;根据基本协议要素,认证待加密数据的传输身份,实现对Modbus/TCP可信协议的定义;利用协议文件中的可信度条件,设置密钥模板,通过移植处理通信文本的方式,确定数据信息样本的扩容总量,完成安全加密接口设计,联合相关应用元件,实现基于Modbus/TCP的无线通信网络安全加密控制系统设计;实验结果表明,所设计系统明文加密时长、密文响应时长之间的相对时延量始终保持为0.1 ms,能够有效实现无线网络对于通信数据的安全性加密。

适用于数据中心低延迟高吞吐量TCP的动态标记配置策略

在数据中心流量传输过程中,传输性能的好坏很大程度上取决于数据中心TCP是否可以满足长短数据流不同的传输性能需求,即长流的高吞吐率和短流的低排队延迟。由于数据中心网络应用主要是在线数据密集型应用(online data intensive application,OLDI)产生大量长流和短流混合的数据流,使长流占用大部分瓶颈链路带宽,造成短流高延迟,影响应用的服务质量。文章提出的动态标记配置(Dynamic-marking Configuration,DMC)策略动态调整瓶颈链路队列长度门限,实现流量的低延迟和高吞吐量传输,并降低数据流错过最后期限的比例。

网络通信中嵌入式TCP/IP单片机技术研究

嵌入式传输控制协议/网际协议(Transmission Control Protocol/Internet Protocol,TCP/IP)单片机技术是网络通信中一项重要的技术。主要从嵌入式TCP/IP单片机技术的概述、硬件结构、软件设计进行详细介绍,提出一种嵌入式TCP/IP单片机的软件设计方法,并将其应用于网络通信,以提高网络通信的稳定性和可靠性,并提高数据传输质量。

基于TCP/IP的多媒体技术支持系统设计和实现

随着网络技术的发展,网络技术逐渐渗透到各个行业领域,很多领域顺应时代发展进行多样化的变革。其中,实际生产和工作中使用多媒体技术支持系统可以共享网络资源,提高资源的利用率和工作效率。文章介绍了传输控制协议/网际协议(Transmission Control Protocol/Internet Protocol,TCP/IP),并对基于TCP/IP的多媒体技术支持系统进行了设计和实现。

基于共享存储技术的乱序TCP分段重排电路设计

传输控制协议(Transmission Control Protocol,TCP)处理引擎可以广泛应用于数据中心的各类型服务器,降低处理器负荷。为提高TCP协议处理引擎处理数据的分段效率,设计了一种基于共享存储技术的乱序TCP分段重排电路,其采用静态随机存储器(Static Random Access Memory,SRAM)存储,具有结构简单、存储资源利用率高、低时延的特性,可有效克服内容寻址存储器(Content Addressable Memory,CAM)或三态内容可寻址存储器(Ternary Content Addressable Memory,TCAM)高功耗以及可扩展性差的缺点,同时满足上千条连接的工作需求;分析了电路的具体结构、关键调度算法和工作流程,并进行了仿真。电路基于Xilinx ZYNQ 7000系列的现场可编程门阵列(Field-Programmable Gate Array,FPGA)实现,对主要硬件资源消耗进行了综合分析。

MANET中TCP改进研究综述

传统TCP(transmission control protocol)本是为有线网络设计,它假设包丢失全是由网络拥塞引起,这个假设不能适应于MANET (mobile ad hoc network),因为MANET 中除了拥塞丢包以外,还存在由于较高比特误码率、路由故障等因素引起的丢包现象.当出现非拥塞因素丢包时,传统 TCP 将错误地触发拥塞控制,从而引起TCP 性能低下.任何改进机制都可以分为发现问题和解决问题两个阶段.首先概括了 MANET 中影响 TCP 性能的若干问题;然后针对发现问题和解决问题两个阶段,详细地对每一阶段中存在的各种可行方法进行了分类、分析和比较;最后指出了 MANET 中 TCP 性能优化的研究方向.

一种异构网络TCP拥塞控制算法

针对互联网中端对端带宽、时延和丢包率等的差异性日益加剧,导致TCP传输性能严重退化,该文提出一种链路自适应TCP拥塞控制算法(INVS)。INVS在拥塞避免阶段初期采用基于指数函数的凸窗口增长函数,以提高链路利用率;在窗口增长函数中引入了自适应增长因子实现窗口增长速率与链路状态相匹配;采用了自适应队列门限的丢包区分策略以提高无线环境下TCP的性能。性能分析和评估表明,INVS提高了TCP拥塞控制算法的吞吐量、公平性、链路利用率和RTT公平性。

改进的无线网络TCP协议跨层设计方法

针对传统TCP协议的拥塞控制机制在无线网络中不能很好地解决数据丢失的问题,提出一种改进的无线网络TCP协议跨层设计方法——NTCP。NTCP将传统TCP功能分割为传输速率控制和数据完整性控制2个部分,避免使用转发节点信息的方法,最大限度地利用无线资源。该方法与传统TCP-Reno方法相比,能提高无线网络的吞吐量,其稳定性和速率自适应能力也有较好的改善。

Ad Hoc中的TCP改进方案——Adaptive ADTCP

在分析无线自组网特点及其对TCP性能影响的基础上,提出了一种能够自适应无线自组网状态的TCP改进方案(Adaptive ADTCP)。Adaptive ADTCP在明确辨识网络状态的前提下,首先根据前向路径跳数自适应地调整拥塞窗口增长因子,限制源节点TCP拥塞窗口过分增长,避免造成网络拥塞;同时源节点TCP根据当前拥塞窗口自适应改变发送的分组长度,充分利用网络资源。仿真实验表明,在网络重负载和节点高速移动情况下,Adaptive ADTCP对数据传输的吞吐量有较大提升。