多阶段虚通道控制中虚通道拓扑优化的神经网络方法

在ＡＴＭ网络中,必须确定一种有效的虚通道（下称ＶＰＶｉｒｕａｌＰａｔｈ）控制策略以提高网络资源垢利用率,多阶段ＶＰ控制方法被设计成对ＶＰ分三阶段进行调整,每一阶段实现特定的任务,分析表明,此方法具有很多优点,本文首先给出了此问题的数学形式,然后提出一种神经网络方法加以解决,数值实验结果表明,本方法能够以极高的稳定性和有效性获得最优或近优解。     

多信道无线通信网混合业务接入控制的离散排队分析

基于无线通信网的运行机制、实时性和非实时性混合业务对无线通信网络不同服务质量(QoS)要求,设计了实时性业务优先接入控制策略,建立了无线通信网络的混合业务带有优先接入控制的多服务台离散时间排队模型Geo1 Geo2/Geo1,Geo2/s,s(PP)。并且应用矩阵几何解方法,对该排队模型进行精确分析,得到了系统的主要性能指标:实时性业务和非实时性业务的平均队长、实时性业务的阻塞概率、系统信道利用率等结果。     

片上网络的动态虚通道分配策略

针对片上网络（NoC）的传统的静态虚通道分配不能很好适应非平衡的业务负荷问题,本论文提出了NoC动态虚通道分配策略。在静态虚通道分配基础上,动态分配虚通道通过实时监测节点端口的包流量的方向,决定分配给该端口的虚通道数目。动态虚通道资源可以在所有端口间共享,并根据通信业务需求动态调度。在二维meshNoC上的仿真表明,动态虚通道分配策略不仅节约了存储器资源,而且对NoC传输延时有一定的改善。     

具有多优先级虚通道的ATM网络综合自愈策略

在构建以ＡＴＭ技术为核心的宽带综合业务数字网中，对网络的生存性提出了越来越高的要求。分析了ＡＴＭ网络中的各种自愈技术，提出了一种具有多优先级虚通道的综合自愈策略，并对其进行了计算机模拟验证。     

多级门限服务轮询系统MAC离散时间控制协议模型分析

 本文提出了一种新的多级门限服务轮询系统MAC控制协议的分析模型.采用嵌入马尔可夫链理论,对离散时间的多级门限服务轮询系统进行了分析,获得了轮询时刻系统队长的概率母函数,精确解析了系统的平均排队队长、平均循环周期、信息分组的平均等待时延.通过对多级门限服务轮询系统的控制机理研究,分析获得了m控制参数的有效控制取值大小和系统的相关特性.多级门限服务轮询系统综合了基本门限服务轮询系统和完全服务轮询系统,在轮询系统的MAC控制协议的应用方面更为有效.     

离散时间信号频域分析中的概念辨析

本文辨析了"信号与系统"课程中离散时间信号频域分析中的三个概念,提出了以离散傅里叶级数为切入点,顺序引出离散时间傅里叶变换和离散傅里叶变换的内容编排方式,其特点在于将离散傅里叶变换作为离散时间傅里叶变换在离散频点上的计算工具。这种编排方式避免了离散傅里叶级数与离散傅里叶变换的形式和概念混淆,适应了计算机仿真在"信号与系统"课程中广泛应用的趋势。对实现中的几个细节问题进行了具体分析,并给出基于门信号的信号仿真实例。     

离散时间多重休假的Geom<em>x/G/1 排队系统的队长分布

近几年来,由于在制造系统与电讯交换系统的设计和控制中和在计算机通信网络的模型刻画和分析中的广泛应用,使得离散时间排队系统受到越来越多的注意.本文考虑离散时间多重休假成批到达的Geom/G/1排队系统,从任意初始状态出发,使用全概率分解技术和u-变换,研究了队长的瞬态性质和稳态性质,首次导出了队长瞬态分布的u-变换形式的递推表达式和队长稳态分布的递推表达式,进一步也获得稳态队长的随机分解结果.特别地,通过本文可直接获得一系列特殊离散时间排队系统相应的结果.     

两类周期查询式完全服务排队系统研究

本文对时间连续型非对称周期查询式完全服务排队系统进行了分析,并与时间离散型周期查询式完全服务排队系统(赵东风,1994)进行了对比研究。在两种系统取相同的系统参数值的条件下,给出两类排队服务系统的分析结果。     

离散时间系统边界条件的确定准则

现用《信号与系统》教材中，有关离散时间系统数学模型──差分方程，其求解方法一般均先分别解出零输入响应和零状态响应而后合成全响应，很少涉及经典求解方法及如何正确地选取边界条件的问题。本文通过对离散时间系统在不同激励情况下的讨论，提出了经典求解法边界条件的确定准则和优化方法，以澄清学生在学习中的模糊认识，并作为现用教材的补充。     

基于虚拟时间反转镜的水声OFDM信道均衡

针对水声信道对正交频分复用(OFDM)系统带来的符号间干扰(ISI)问题,提出了虚拟时间反转镜(VTRM)信道均衡算法,该算法具有时间压缩特性和频域相位共轭特性,可以有效缩短信道长度,减小多途信道带来的相位畸变,采用匹配追踪(MP)算法估计信道冲激响应,可以精确的估计出水声信道的幅度、时延和相位信息,为虚拟时反信道均衡提供准确的信道信息,改进了传统匹配相关信道估计方法估计精度低、无法估计信道相位信息的缺点。仿真、水池和湖上实验结果表明,OFDM水声通信系统中,VTRM信道均衡技术性能优于被动时反镜(PTRM)信道均衡和最小平方(LS)信道均衡。     

A shared-memory virtual channel queue for ATM broadband terminal adaptors

In order to take advantage of the low entry cost of the future public ATM (asynchronous transfer mode) network with shared facilities, it is highly desirable to interconnect different hosts and local area networks (LANs) to the ATM network. The interface between the computer hosts or LANs and the ATM network, commonly called a broadband terminal adaptor (BTA), provides the necessary format conversion for the data packets and the ATM cells. It is conceivable that multiple packets from different virtual channels are interleaved as they arrive at the receive-end BTA. The BTA must have a sufficiently large buffer, called a virtual channel queue (VCQ), to temporarily store the partially received packets. Once a complete packet has been received, it is forwarded to the host or LAN. Whenever the buffer fills with all incomplete packets, a packet must be discarded to make room for others. In this paper, we first study, through computer simulations, the buffer size requirement of a shared-memory VCQ for different numbers of virtual channels at various packet loss probabilities. We then present two different implementation architectures for the shared-memory VCQ, and compare their hardware complexity. The second architecture with linked-queue approach, adopted in our work, requires less buffer and has better scalability to accommodate a large number of virtual channels. Various possible error conditions, such as cell losses in the ATM network and the VCQ buffer overflow, are considered. Corresponding solutions are proposed and included in the VCQ designs.     

PDAVQ：一种基于PD控制的自适应虚拟队列管理算法

提出了一种新的基于比例差分控制的自适应虚拟队列管理(AVQ)算法—PDAVQ,用于对网络链路中产生的拥塞进行控制,以达到有效利用网络带宽,使整个网络系统达到稳定,缓解网络拥塞的目的。而且本文对所提算法运用控制理论对系统的稳定性进行了证明,给出了满足系统稳定性条件的参数选择方法和 PDAVQ 算法的具体描述。最后,通过 ns2 仿真实验与现有的 AVQ 算法比较,结果表明,所提 PDAVQ 算法具有较高的吞吐率、较低的链路延迟和数据丢失率,并能更快的使整个网络系统达到稳定,具有较好的网络性能。     

A hybrid virtual network mapping algorithm based on threshold load

The virtual resource management architecture for satellite networks currently suffers from a very poor virtual network mapping success rate. This arises because of the need to map multiple heterogeneous virtual networks to the underlying satellite network. Most heuristic algorithms divide virtual network mapping into node mapping and link mapping, which aims to reduce the complexity of the problem. However, this approach is not well suited to highly dynamic satellite networks. In this paper, we propose a hybrid virtual network mapping algorithm that is based on threshold load. This takes the overall load for the nodes as its optimization objective, and combines the idea of backtracking contained in 1‐stage mapping methods and the idea of global optimization contained in 2‐stage mapping methods. The algorithm reduces the complexity of backtracking computation, while avoiding any incompleteness that might result from separating nodes and link mapping. The success rate for virtual network mapping is thus improved, as is the utilization rate for satellite network resources.     

Research on space focusing virtual coverage based on orthogonal frequency time reversal method

To solve the problem of information leakage and coverage efficiency in ultra-dense wireless network,the orthogonal frequency-time reversal virtual coverage scheme was proposed.At first,different wireless reversal channels with lower correlation were distinguished by orthogonal carries.Next,after time reversal,the space focusing of each target signal was realized around the terminal.Then,theoretical expressions of the signal coverage and the signal-interference-to-noise ratio were derived and proved.Ultimately,the virtual coverage was shaped,meeting the requirements of users.The coverage of unrelated user not belonging to system was reduced.The results show that those unrelated users are difficult to receive the target signal because of virtual coverage.In addition,the system has higher capacity and security rate of reliable transmission without any more power or antennas.     

GI/Geom/1 queue based on communication model for mesh networks

In mesh networks architecture, it should be permitted to visit the mobile client points. Whereas in mesh networks environment, the main throughput flows usually communicate with the conventional wired network. The so‐called gateway nodes can link directly to traditional Ethernet, depending on these mesh nodes, and can obtain access to data sources that are related to the Ethernet. In wireless mesh networks (WMNs), the quantities of gateways are limited. The packet‐processing ability of settled wireless nodes is limited. Consequently, throughput loads of mesh nodes highly affect the network performance. In this paper, we propose a queuing system that relied on traffic model for WMNs. On the basis of the intelligent adaptivenes, the model considers the influences of interference. Using this intelligent model, service stations with boundless capacity are defined as between gateway and common nodes based on the largest hop count from the gateways, whereas the other nodes are modeled as service stations with certain capacity. Afterwards, we analyze the network throughput, mean packet loss ratio, and packet delay on each hop node with the adaptive model proposed. Simulations show that the intelligent and adaptive model presented is precise in modeling the features of traffic loads in WMNs. Copyright © 2013 John Wiley & Sons, Ltd.     

基于AHP的靶场测控系统综合性能评估

针对目前测控站维护需求,提出了基于AHP的测控系统性能评估方法,设计并实现了评估系统功能。该方法以自动化测试技术为基础,通过层次模型构建、权重计算和指标量化等关键技术的研究,对系统实战性能进行客观评价。系统应用结果表明,评估方法切实可行。评估结果可为维护策略制定和测控任务实施提供可靠的数据支持。     

基于虚拟分割机制的多服务交换路由器的研究

本文提出了一处基于虚拟分割机制的可编程多服务器由器实现结构：PVSMR，并对它的三个层面的主要构成及其关键技术进行了深入研究。PVSMR基于一种有效而灵活的资源虚拟分割算法，它能够提供与多类应用相适应的、灵活的报文处理和转发控制能力。     

基于NTP协议的网络时间服务系统的实现

本文介绍了网络时间协议的基本工作原理,简要分析了在网络路径对称和不对称两种情况下的网络时延问题.论述了网络时间服务器的构建方法和网络授时软件的设计流程.应用数据统计,对网络时延和时差作了详细分析,给出了在软件设计中处理与网络时延和时差相关问题的方法.最后阐明了建立网络时间服务体系的必要性.