CIMS环境下的通信网络协议MAP

本文从计算机综合制造系统(CIMS)的基本概念开始,逐步阐述了CIMS 的组成、CIMS 环境下的通信网络及其最新版本的MAP/3.0协议的基本内容、拓朴结构及其组成形式,最后介绍了MAP的发展趋势和国内外研究的现状.

用于通信网络协议开发的形式化方法

随着形式化方法和技术日趋完善,网络协议开发也逐渐向形式化描述方法过渡和发展,并逐渐渗透到网络协议分析、综合及测试的各个环节中,形成应用于各个环节的软件工程方法。本文通过对通信网络协议的要素进行分析,并对网络协议形式化方法、形式化模型及描述进行阐述,在此基础上对通信网络协议的形式化方法进行了探究,并给出了一些自己的看法和建议。

微通讯网络协议的构成与工作原理

对拨号调制解调器中广泛应用的ＭＮＰ（ＭｉｃｒｏｃｏｍＮｅｔｗｏｒｋｉｎｇＰｒｏｔｏｃｏｌ）协议进行了深入的研究，详细讨论了该协议的总体构成与工作原理，并对采用ＭＮＰ协议的通讯过程进行了仔细地分析，对提高我国高档调制解调器的研究水平有较大的现实意义。

EWMA算法在无线通信协议速率选择中的应用

如何根据无线环境的变化实时选择一个可靠的发送速率,进而保证数据传输的可靠性是无线通信研究的热点。针对传统累积和平均法(Cumulative Sum Average,CUSUMA)由于计算机存储数据位数的有限性可能导致的数据值超过计算机最大数据类型表示范围,进而造成统计数据丢失的问题,提出基于指数加权移动平均(Exponentially Weighted Moving Average,EWMA)算法,计算对应速率下的数据发送成功率,并根据计算出的成功率实现动态速率选择。该算法可用于解决通用平均值算法导致的因数据过大造成的统计数据丢失问题。

基于5G通信技术的现代机场航班信息管理系统设计

针对原4G通信网络的机场管理系统带宽小、易受干扰信息影响导致管理数据存在误差的问题,设计了基于5G通信技术的现代机场航班信息管理系统。采用IEEE 802.15.4作为5G通信网络协议,利用5G通信技术采集并传输现代机场实时数据,以提升数据传输速率和质量。在原有的PXA310型号数据处理器上接入数字信号处理(DSP)协同处理器,以增强系统对大量数据荷载的处理能力。根据实时通信的飞机运行数据,实现管理系统的航班数据自动更新、航班延误预警等管理功能。系统测试结果表明:在有、无干扰环境下,该系统的航班数据更新错误率分别为0.78%和0.31%,航班延误预测偏差分别为3.38 min和1.63 min,系统运行吞吐量均能够控制在1 210个/s以上。该系统具有较高的实际应用价值。

用于智能电网的一种认知无线路由算法研究

为扩大通信网络的可利用带宽,智能的分配网络资源,该文围绕智能电网的通信业务服务质量要求,建立面向智能电网Ad hoc通信协议的一种认知无线电网络路由方法。该方法基于耗能和延时最小的原则,根据节点个数、传输速率的要求,对其路由策略以及相关的频谱分配方案展开研究,为构建高效而稳定的Ad hoc智能电网通信网络协议提供一种新思路和设计理念,最终通过数值模型仿真验证其性能优于传统算法,非常适合智能电网方面的应用。

Bidirectional Quantum Secure Direct Communication Network Protocol with Hyperentanglement

We propose a bidirectional quantum secure direct communication(QSDC) network protocol with the hyperentanglment in both the spatial-mode ad the polarization degrees of freedom of photon pairs which can in principle be produced with a beta barium borate crystal.The secret message can be encoded on the photon pairs with unitary operations in these two degrees of freedom independently.Compared with other QSDC network protocols,our QSDC network protocol has a higher capacity as each photon pair can carry 4 bits of information.Also,we discuss the security of our QSDC network protocol and its feasibility with current techniques.

Principles and Defense Strategies of DNS Cache Poisoning

DNS is one of the most important basic infrastructures of the Internet, attacks on which will prevent the Internet from working properly. Therefore, its security is receiving great concern. This paper analyzes the principles of both traditional and novel （Kaminsky） DNS cache poisoning, presents attack samples and describes the whole attack process in detail. After verifying the potential harm of DNS cache poisoning, the paper gives out several defense strategies.

New Optimal Power Allocation for Bidirectional Communications in Cognitive Relay Network Using Analog Network Coding

Cognitive radio and cooperative communication can greatly improve the spectrum efficiency in wireless communications.We study a cognitive radio network where two secondary source terminals exchange their information with the assistance of a relay node under interference power constraints.In order to enhance the transmit rate and maintain fairness between two source terminals,a practical 2-phase analog network coding protocol is adopted and its optimal power allocation algorithm is proposed.Numerical results verify the superiority of the proposed algorithm over the conventional direct transmission protocol and 4-phase amplify-and-forward relay protocol.

Research and improvement on packet capture mechanism in linux for high-speed network

With the increasing enlargement of network scale and the rapid development of network techniques, large numbers of the network applications begin to appear. Packet capture plays an important role as one basic technique used in each field of the network applications. In a high-speed network, the heavy traffic of network transmission challenges the packet capture techniques. This paper does an in-depth analysis on the traditional packet capture mechanisms in Linux, and then measures the performance bottleneck in the process of packet capture. The methods for improving the packet capture performance are presented and an optimized packet capture scheme is also designed and implemented. The test demonstrates that the new packet capture mechanism (Libpacket) can greatly improve the packet capture performance of the network application systems in a high-speed network.

On-demand multicast routing protocol based on node classification in MANET

An improved on-demand multicast routing protocol(ODMRP), node classification on-demand multicast routing protocol(NC-ODMRP), which is based on node classification in mobile ad hoc networks was proposed. NC-ODMRP classifies nodes into such three categories as ordinary node, forwarding group(FG) node, neighbor node of FG node according to their history forwarding information. The categories are distinguished with different weights by a weight table in the nodes. NC-ODMRP chooses the node with the highest weight as an FG node during the setup of forwarding group, which reduces a lot of redundant FG nodes by sharing more FG nodes between different sender and receiver pairs. The simulation results show that NC-ODMRP can reduce more than 20% FG number of ODMRP, thus enhances nearly 14% data forwarding efficiency and 12% energy consumption efficiency when the number of multicast senders is more than 5.

Using CSMA/CD for Ethernet Passive Optical Network (EPON)

Using CSMA/CD for EPON can eliminate the augmentations, such as multi-point control protocol and point-to-point emulation, added to the existing 802.3 architecture due to the incompatibility of PON to Ethernet. Both full-duplex EPON system and half-duplex EPON system using CSMA/CD were proposed. In the full-duplex EPON, CSMA/CD is used as the upstream MAC protocol. In the half-duplex EPON system, both upstream and downstream traffic contend for the optical channel through CSMA/CD protocol. The upstream lightwave redirection and collision detection techniques were given. By the analysis and simulation, the throughput performance of the half-duplex EPON system is proven to be as well as that of the existing high speed half-duplex Ethernet LAN.

Performance analysis of an iSCSI-based unified storage network

In this paper, we introduced a novel storage architecture 'Unified Storage Network', which merges NAC( Network Attached Channel) and SAN( Storage Area Network) , and provides the file I/O services as NAS devices and provides the block I/O services as SAN. To overcome the drawbacks from FC, we employ iSCSI to implement the USN( Unified Storage Network) . To evaluate whether iSCSI is more suitable for implementing the USN, we analyze iSCSI protocol and compare it with FC protocol from several components of a network protocol which impact the performance of the network. From the analysis and comparison, we can conclude that the iSCSI is more suitable for implementing the storage network than the FC under condition of the wide-area network. At last, we designed two groups of experiments carefully.

Seamless Handover for IMS over Mobile-IPv6 Using Context Transfer

Mobility support for the next generation IPv6 networks has been one of the recent research issues due to the growing demand for wireless services over internet.In the other hand,3GPP has introduced IP Multimedia Subsystem as the next generation IP based infrastructure for wireless and wired multimedia services.In this paper we present two context transfer mechanisms based on predictive and reactive schemes,to support seamless handover in IMS over Mobile IPv6.Those schemes reduce handover latency by transferring appropriate session information between the old and the new access networks.Moreover,we present two methods for QoS parameters negotiations to preserve service quality along the mobile user movement path.The performances of the proposed mechanisms are evaluated by simulations.

A Kind of Multi-party Non-repudiation Protocol with Consistent Evidence

With development of electronic com- merce, non-repudiation protocol as the basal component of non-repudiation service has done more and more important functions. Comparing with lots of work on two-party non-repudiation, there are less work on multi-party non-repudiation protocol. Multi-party protocol is more complex and facing more challenge of collusion attack. In this paper we give a kind of multi-party non-repudiation protocol based on off-line TTP with consistent evidence. Consistent evidence is a property that can not only simplify the process of disputation resolving, but also make the service more friendly to users, which means that whether or not TTP involves, evidences participants obtained are consistent. In the meanwhile we analyze the collusion attack that multi-party protocol facing, our protocol can prevent collusion attack.

Exploring Application Layer Protocol Relationships in SoftSwitch

Relationships between application layer protocols in softswitch are explored in this paper.Two notions, i.e.protocol relationship and protocol grouping, are proposed, which are not clearly defined and even not paid much attention to before.On the basis of a well known protocol relationship named protocol conversion, three novel protocol relationships including protocol collaboration relationship, protocol cooperation relationship and protocol independent relationship are presented, so that protocol relationships are classified into four types.According to the functionality and purpose of each protocol, main protocols related to softswitch are divided into five groups.As to protocol conversion in softswitch, information flow trail(IFT) is utilized to facilitate problem solving.A decision rule for protocol conversion mode is proposed to guide how to choose between direct conversion and indirect conversion.A property of protocol relationships in softswitch is induced from all kinds of service scenarios of softswitch.This property summarizes protocol relationships within each protocol group or between two specific protocol groups.A merit of protocol grouping together with classification of protocol relationship is also presented.The effort of this paper pushes the protocol engineering to go ahead.

A QoS Aware Service Composition Protocol in Mobile Ad Hoc Networks

A novel decentralized service composition protocol was presented based on quality of service (QoS) for mobile ad hoc networks (MANETs).A service composition in MANETs is considered as a service path discovery in a service network.Based on the concept of source routing,the protocol integrates route discovery, service discovery and service composition and utilizes a constrained flooding approach to discover the optimal service path.A service path maintenance mechanism was exploited to recover broken service paths.Simulation experiments demonstrate that the proposed protocol outperforms existing service composition protocols.

Automatic Configuration in NTP

NTP is nowadays the most widely used distributed network time protocol, which aims at synchronizing the clocks of computers in a network and keeping the accuracy and validation of the time information which is transmitted in the network. Without automatic configuration mechanism, the stability and flexibility of the synchronization network built upon NTP protocol are not satisfying. P2P’s resource discovery mechanism is used to look for time sources in a synchronization network, and according to the network environment and node’s quality, the synchronization network is constructed dynamically.

Research on IPv6 Transition Evolvement and Security Architecture of Smart Distribution Grid Data Communication System

Smart distribution grid needs data communication systems as a support to complete their important functions. The smart distribution grid of the data and information are increasingly adopting internet protocol and Ethernet technology. The IP addresses are more and more important for the smart distribution grid equipment. The current IPv4 protocol occupies a dominant position; therefore, the challenges of the evolution to IPv6 and network security are faced by data communication systems of the smart distribution grid. The importance of data communications network and its main bearer of business were described. The data communications network from IPv4 to IPv6 evolution of the five processes and four stages of the transition were analyzed. The smart distribution grid data communications network security and types of their offensive and defensive were discussed. And the data communications network security architecture was established. It covers three dimensions, the security level, the communications network security engineering and the communications network security management. The security architecture safeguards the evolution to IPv6 for the smart distribution grid data communication systems.

Research on the Network Intrusion Detection System based on Modified Particle Swarm Optimization Algorithm

In this paper, we conduct research on the network intrusion detection system based on the modified particle swarm optimization algorithm. Computer interconnection ability put forward the higher requirements for the system reliability design, the need to ensure that the system can support various communication protocols to guarantee the reliability and security of the network. At the same time also require network system, the server or products have strong ability of fault tolerance and redundancy, better meet the needs of users, to ensure the safety of the information data and the good operation of the network system. For this target, we propose the novel paradigm for the enhancement of the modern computer network that is innovative.