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...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.展开更多
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 Trans...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.展开更多
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 performanc...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%.展开更多
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...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。展开更多
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...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.展开更多
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 tend...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.展开更多
The goal of this paper is to propose a fast and secure multi-stage image compression-decompression system by using a wireless network between two Personal Computers (PCs). In this paper, the Principal Component Analys...The goal of this paper is to propose a fast and secure multi-stage image compression-decompression system by using a wireless network between two Personal Computers (PCs). In this paper, the Principal Component Analysis (PCA) technique is used for multi-stage image compression and Inverse Principal Component Analysis (IPCA) for multi-stage image decompression. The first step of the proposed system is to select the input image, the second step is to perform PCA up to 9 times on the input image, this compression, and after multi-stage compression process then the third step begins by transforming across wireless Ad hoc Network (WANET) to the second computing device, forth step start with multi-stage decompression process up 9 times. The proposed system for different images is transferred over the wireless network using Transmission Control Protocol/Internet Protocol (TCP/IP), which is programmed using the network role property of the MATLAB program. The proposed system implements 25 different images correctly (100%). The main contribution of this paper is that we are dealing with the black image at the end of the compressed process ad start with a black image at the start of the decompressed process of this proposed system. In this work, the compressed and uncompressed images are compared with each other in their size and transmission time. This system can be very useful in networks because they provide a high level of protection to the transmitted data from hackers because they cannot guess how much the image has been compressed or what kind of information the image represents.展开更多
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 m...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.展开更多
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 applica...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。展开更多
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...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。展开更多
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(Transmiss...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。展开更多
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...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.展开更多
文摘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.
基金High-Tech Research and DevelopmentProgram of China (No. 2003AA123310)
文摘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.
文摘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%.
文摘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。
文摘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.
文摘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.
文摘The goal of this paper is to propose a fast and secure multi-stage image compression-decompression system by using a wireless network between two Personal Computers (PCs). In this paper, the Principal Component Analysis (PCA) technique is used for multi-stage image compression and Inverse Principal Component Analysis (IPCA) for multi-stage image decompression. The first step of the proposed system is to select the input image, the second step is to perform PCA up to 9 times on the input image, this compression, and after multi-stage compression process then the third step begins by transforming across wireless Ad hoc Network (WANET) to the second computing device, forth step start with multi-stage decompression process up 9 times. The proposed system for different images is transferred over the wireless network using Transmission Control Protocol/Internet Protocol (TCP/IP), which is programmed using the network role property of the MATLAB program. The proposed system implements 25 different images correctly (100%). The main contribution of this paper is that we are dealing with the black image at the end of the compressed process ad start with a black image at the start of the decompressed process of this proposed system. In this work, the compressed and uncompressed images are compared with each other in their size and transmission time. This system can be very useful in networks because they provide a high level of protection to the transmitted data from hackers because they cannot guess how much the image has been compressed or what kind of information the image represents.
基金Supported by the National Natural Science Foundation of China (No.60496314)the Chinese 863 National High Technology Program (No.2002AA783043).
文摘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.
文摘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。
文摘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。
文摘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。