基于GPRS的远程监控系统

为了提高现代远程监控系统的实时性、可靠性,为了更加地促进工业监控系统的智能化和信息化,采用了一种基于GPRS远程监控系统的总体设计方案,通用分组无线数据业务（GPRS）是以端对端的分组传输与交换方式达到为用户提供发送和接收高速数据、低速数据以及信令的多种业务集合。在电力系统、石油勘测、水利、交通运输等领域有着非常重要的作用。     

A Multilayer Optical Packet Switching Network Based on the Kautz Graph and Optical Passive Star Couplers

The multihop optical network is the most appropriate solution to satisfy the increasing applications of Internet services. This paper extends the regular Kautz graph to one with multiple layers in order to produce more architectural variations. The connectivity between adjacent layers utilizes the systematic connection patterns of a regular Kautz graph. A routing algorithm based on its property is presented. Optical passive star (OPS) couplers are adopted to implement our new topologies. Three scheduling criteria that can solve the contention problem in the intermediate nodes are evaluated and compared in terms of their capability to improve the accessibility.     

包分类算法在防火墙中的应用研究

包分类算法的性能直接影响数据包的收发速度,决定了网络的时延和吞吐量。防火墙中使用分类算法进行过滤规则的匹配查找,能有效降低规则匹配搜索时间,极大地提升防火墙的性能。递归流分类（RFC,Recursive Flow Classification）算法查找速度快,但预处理时间长,存储开销大。现在RFC算法的基础上,结合哈希树算法对数据包各字段分开处理。将两种算法结合,综合考虑了空间和时间性能,不仅减少了存储开销,而且能保持相对快的查找速度。     

光分组交换节点技术

文章首先介绍了光分组交换网络的分类和光分组交换节点的基本结构,接着详细讨论了全光分组交换节点设计和实现中的关键问题:交换结构的设计、光存储的实现以及分组拥塞问题的解决方案。     

Packet Error Rate Distribution Between Random Bluetooth Piconet Pairs

The packet error rate between two piconets depends on the temporal alignment of their packets and the spectral alignment of the intervals from which the frequencies in their hop sequence are chosen. The relationship between two randomly paired piconets is one of over 828 billion possible relationships. We define these relationships and derive an expression for determining the packet error rate for a specific pair of piconets using single-slot packets. We derive the probability mass function for the packet error rate and extend it to provide the possible packet error rates for an arbitrary number of neighboring piconets. We also derive a probability mass function for the goodput of a piconet with a neighboring piconet. The probability mass functions for the packet error rate is bimodal, meaning the expected value of the goodput or packet error rate is not a good choice for piconet performance analysis. Brian S. Peterson is Chief of the Advanced MASINT Research and Requirements Branch at the National Air and Space Intelligence Center, Wright-Patterson AFB, Ohio. He received the B.S.E.E degree in 1991 from the United States Air Force Academy, an M.S. degree in Systems Engineering in 1995 from, and an M.S.E.E. degree from Florida State University in 1998. He received his Ph.D. degree in Electrical Engineering in 2005 from the Air Force Institute of Technology. Dr. Peterson's research interests include computer communication protocols and wireless networking. Dr. Peterson is a member of the IEEE. Rusty O. Baldwin is an Associate Professor of Computer Engineering in the Department of Electrical and Computer Engineering at the Air Force Institute of Technology, Wright-Patterson AFB, Ohio. He received the B.S.E.E degree (with honors) in 1987 from the New Mexico State University and the M.S. degree in Computer Engineering in 1992 from AFIT. He received his Ph.D. degree in Electrical Engineering in 1999 from Virginia Polytechnic Institute and State University. Dr. Baldwin's research interests include computer communication protocols, information warfare, and wireless networking. Dr. Baldwin is a Senior member of the IEEE. Richard A. Raines is an Associate Professor of Electrical Engineering in the Department of Electrical and Computer Engineering at the Air Force Institute of Technology (AFIT), Wright-Patterson AFB, Ohio. He received the B.S.E.E degree (with honors) in 1985 from the Florida State University and the M.S. degree in Computer Engineering in 1987 from AFIT. He received his Ph.D. degree in Electrical Engineering in 1994 from Virginia Polytechnic Institute and State University. Dr. Raines' research interests include computer communication protocols, information security, and wireless networking. Dr. Raines is a Senior member of the IEEE.     

DHCPv6 Relay报文转发功能实现研究

IPv6可以解决当前地址资源匮乏问题,而动态主机配置协议能够实现IPv6地址参数配置的自动化,降低维护人员的劳动强度.基于rfc3315区分不同类型的DHCPv6报文,对13种报文类型的中继过程做出相应处理.在路由器设备上实现中继配置功能和报文转发功能,使客户端即插即用.客户端和服务器不在同一链路时,中继代理有效解决地址配置问题,使IPv6地址成功申请.     

Performance analysis and hardware implementation of a nearly optimal buffer management scheme for high‐performance shared‐memory switches

Burst traffic is a common traffic pattern in modern IP networks, and it may lead to the unfairness problem and seriously degrade the performance of switches and routers. From the perspective of switching mechanism, the majority of commercial switches adopt the on‐chip shared‐memory switching architecture, and high‐speed packet buffer with efficient queue management is required to deal with the unfairness and congestion problem. In this paper, the performance of a shared‐private buffer management scheme is analyzed in detail. In the proposed scheme, the total memory space is split into shared area and private area. Each output port has a private memory area that cannot be used by other ports. The shared area is completely shared among all output ports. A theoretical queuing model of the proposed scheme is formulated, and closed‐form formulas for multiple performance parameters are derived. Through the numerical studies, we demonstrate that a nearly optimal buffer partition policy can be obtained by setting an equally small amount of private area for each queue. This work is validated by simulations as well as hardware experiments. Software simulations show that the proposed scheme performs better than existing methods, and packet dropping caused by burst traffic can be significantly reduced. Besides, a prototype of the buffer management module is implemented and evaluated in field programmable gate array platform. The evaluation shows that the proposed scheme can ensure the efficiency and fairness while keeping a high throughput in real workload.     

数字电视传送流丢包和丢包率研究

定义了数字电视传送流丢包,并通过实验指出丢包对电视信号有重要影响,建议把定义的丢包率作为评价数字电视信号传输质量的客观指标之一.为此,提出了两种分析丢包和统计丢包率的算法,并进行了实验验证.     

TETRA数字集群系统分组数据功能的实现

本文提出了一种TETRA数字集群系统中的分组数据功能设计的方法.笔者在研究TETRA系统空中接口协议栈和TETRA分组域的架构的基础上,设计并实现了子网相关汇聚协议实体;重点分析了PDP上下文激活/去激活、分组信道分配与释放、分组数据传输等过程,采用UML语言和C语言混合编程的方法开发了TETRA数字集群系统的分组数据功能.本文最后进行的UML模型仿真和设备测试结果与TETRA协议一致.     

一种基于能量高效的多路径路由编码算法

针对如何降低无线传感网络中的节点能量消耗问题,文章提出了一种基于能量高效的网络模型和编码模型,给出了相应的网络编码策略和能量消耗模式,建立了一种新的基于网络编码多路径路由技术的节点能量有效算法,并以误码率为参照基准,与有关的多路径路由协议算法做了相应的实验比较。仿真结果表明,文章所提出的方法在能量高效、网络生命延长及数据分组传递方面有较好的改进。