一种基于WDM四纤环网的波长分配算法

介绍了一种基于WDM四纤共享保护环网进行波长分配的算法.该算法采用矩阵形式表示波长分配情况,它可以用最少的波长数目经由最短通道实现环网上各站点之间的全连接.最后,对偶数站点的波长分配方法加以改进,用比较简洁的过程获得了相同的波长分配结果.     

All-to-all在千兆以太网集群上的性能分析

MPI_Alltoall全交换操作是集群中常用的集合通信操作之一,针对该操作有多种实现算法.不同的实现算法在具体的物理平台具有不同的性能.本文在目前应用较广的千兆以太网集群平台,分析并对比测试了不同算法的通信性能,为进一步研究全交换优化算法提出可研究的方向和目标.     

All-to-all在千兆以太网集群上的性能分析

MPI—Alltoall全交换操作是集群中常用的集合通信操作之一,针对该操作有多种实现算法。不同的实现算法在具体的物理平台具有不同的性能。本文在目前应用较广的千兆以太网集群平台,分析并对比测试了不同算法的通信性能,为进一步研究全交换优化算法提出可研究的方向和目标。     

Hose不确定模型下一种新的动态选路算法研究

该文讨论了全连接结构的光交换网络在Hose不确定模型下的动态选路问题,并基于Valiant负载平衡机制,提出了一种新的动态选路算法.分配系数可调的负载平衡选路算法(Load Balancing with Adjustable Distribution Fraction, LBADF)。LBADF算法根据网络中各条链路上空闲光路的数目对Valiant负载平衡机制中的分配系数进行动态的调整,从而达到优化网络性能的目的。计算机仿真表明LBADF算法相对于分配系数恒定的VLB算法具有更小的全网呼损率,同时也相应地降低了全网中所有节点对的最大呼损率。     

基于MPI的进程拓扑感知映射研究

本文首先介绍了获取应用程序通信拓扑和物理拓扑的方法,结合进程间通信量和通信频次定义了进程间亲和度,并针对具有分层网络、NUMA效应的硬件系统,设计了相应的进程映射算法.该算法根据进程间的亲和度对进程集合进行划分,在划分过程中构造出和物理拓扑树同构的树状结构,随后在两棵同构树的对应节点上做映射来解决应用程序进程到物理节点、处理核心的映射问题.在一个多核集群系统上的实验表明,使用本文提出的进程映射方法可以有效提高并行应用程序的通信效率,显著减少程序的总体执行时间.     

静态环型波长路由光网络中RWA问题的研究

RWA问题是静态环型波长路由光网络中的一个核心问题.随着RWA优化算法求解方式的简化,算法的运算效率得到了提高,但却牺牲了解的优化性能.如何使优化效率和时间效率协调统一是当前环网波长路由光网络中RWA优化算法设计的难点.本文对静态波长路由光网络中RWA问题进行了阐述,综述了当前国内外的RWA算法,并对静态环网中几种新的算法进行了分析研究.     

基于程控的光纤通信链路自动交换技术

基于程控技术的光通路自动交换技术是一种新的光纤通信链路的自动交换技术,它利用程控技术控制镜面的入射角度,从而达到对反射光路的调整,以实现光自动交换的目的,本技术为光通信链路自动化交换提供了新思路和新方法,为全光网的实现开辟了另一条方向.     

电力通信系统中的光纤全交换方案

为了克服传统的智能光缆网络中无法实现光纤自动全交换的瓶颈,本文提出了一种电力通信系统中的子站的光纤全交换方案,该方案的核心涉及安装在子站中的一种光纤全交换设备,该设备通过一个交换板实现接入到该设备中的任意两根光纤之间的光学连接,从而实现光学全交换。     

FIFO交换网络:一种保持信元次序完整性的多路径ATM交换结构

本文提出了一种新型的自选路由ＡＴＭ多路径交换结构，采用虚拟ＦＩＦＯ缓冲器技术，即能保持信元次序的完整性，又避免了螺旋式交换结构中虚拟信元引起的饱和吞吐量、延迟和信元丢失性能的下降。在均匀通信量和非均匀通信量情况下分析了它的性能，结果表明其最大可达到的饱和吞吐量为７／８，延迟和信元丢失率都比螺旋式结构小很多。同时，该系统无需内部加速，适于ＶＬＳＩ集成。     

光纤工业控制网的研究

本文介绍了电路交换和分组交换相结合的新型光纤工业控制环网的设计与研究,着重考虑了环网的拓扑结构、体系结构、ＭＡＣ协议、帧结构和混合环路控制。     

Broadcast communication operations for hyper hexa-cell interconnection network

The hyper hexa-cell (HHC) interconnection network is relatively a new interconnection network, which is constructed from hexa-cell and hypercube topologies. HHC is developed to support parallel algorithms for solving computation and communication intensive problems. Thus, in order to support solving these problems efficiently, this paper presents two broadcast communication operations for HHC using store-and-forward technique; namely, one-to-all and all-to-all broadcast operations; which allow a message to be transmitted through the shortest path from the source node to all other nodes. The broadcast communication operations are evaluated analytically in terms of communication steps, communication latency, communication cost, and speed over HHC and wraparound square mesh interconnection networks. The analytical results over HHC show that in both one-to-all and all-to-all broadcast operations, the maximum communication steps are \( d + 2\), where d is the dimension of HHC, which is a small integer number. Also, the communication latency increases linearly when the network size increases, and the communication cost for the broadcast operations is equal to O(\(2^{d-1})\). Moreover, the speed of both broadcast operations on d-dimensional HHC is \(d+2\times \) speed of electronic links. In comparison between HHC and wraparound square mesh, one-to-all and all-to-all broadcast communication operations over HHC perform much better than mesh in terms of maximum communication steps, communication latency, and speed.     

协作通信网络中的中继节点选择技术

协作通信作为一种新型的通信模式越来越受到人们的关注,而中继节点选择技术是其关键技术之一,决定了协作能否带来性能增益。文章基于协同节点选择技术的性能评价标准给出了相应的分类方法,对近年来典型的协同节点选择算法并进行分析和比较,得出结论：只有根据系统需求合理地选择、配置中继节点才能更好地优化协同通信的性能。     

On scheduling all-to-all personalized connection and cost-effectivedesigns in WDM rings

We consider the problem of scheduling all-to-all personalized connections (AAPC) in WDM rings. Scheduling one connection for every source-destination pair in a network of limited connectivity provides a way to reduce routing control and guarantee throughput. For a given number of wavelengths K and a given number of transceivers per node T, we first determine the lower bound (LB) on the schedule length, which depends on both K and T. To achieve the LB, either the network bandwidth, the I/O capacity, or both should be fully utilized. This approach first constructs and then schedules circles, each of which is formed by up to four non-overlapping connections and can fully utilize the bandwidth of one wavelength. The proposed circle construction and scheduling algorithms can achieve the LB if K⩽T相似文献   

Reducing Network Cost of Many-to-Many Communication in Unidirectional WDM Rings With Network Coding

In this paper, we address the problem of traffic grooming in wavelength-division multiplexing rings with all-to-all and its generalization to many-to-many service by using network coding. We consider minimizing the number of line terminating equipment on two types of unidirectional rings, namely, single-hub and unhubbed rings, as our objective. In single-hub rings, we investigate the minimum cost provisioning of uniform all-to-all traffic in two cases: where network coding is used to linearly combine data, and where it is not used and data are transmitted without coding. We generalize the service mode to many-to-many and evaluate the cost of provisioning. In unhubbed ring, we propose a multihub approach to obtain the minimum cost provisioning in the case of all-to-all and many-to-many traffic. In each type of ring topology, two network scenarios are considered: first, the distinct communication groups in the ring are node-disjoint, and second, the different groups may have common member nodes. From our numerical results, we find that under many-to-many traffic pattern for both scenarios, network coding can reduce the network cost by 10%–20% in single-hub rings and 1%–5% in unhubbed rings in both network scenarios.      

A general approach for all-to-all routing in multihop WDM optical networks

WDM optical networks provide unprecedented high speed and reliability for message transfer among the nodes. All-to-all routing is a fundamental routing problem in such networks and has been well studied on single hop WDM networks. However, the number of wavelengths to realize all-to-all routing on the single hop model typically is very large. One way to reduce the number of wavelengths is to use k-hop routing, in which each routing path consists of k segments and each segment is assigned a different wavelength, where k usually is a small constant. Because of the complexity of design and analysis for such a routing problem, only few papers discussed and proposed all-to-all routing by k/spl ges/2 hops. However, the proposed algorithms are usually exceeding complicated even for ring topologies. Often, an ad hoc approach is employed to deal with each individual topology. In this paper we propose a generic method for all-to-all routing in multi-hop WDM networks, which aims to minimize the number of wavelengths. We illustrate the approach for several optical networks of commonly used topology, including lines, rings, tori, meshes, and complete binary trees. For each case an upper bound on the number of wavelengths is obtained. The results show that this approach produces clear routing paths, requires less wavelengths, and can easily incorporate load balancing. For simple topologies such as lines and rings, this approach easily produces the same bounds on the number of wavelengths that were hard-obtained previously. Moreover, this general approach provides a unified routing algorithm for any d-dimensional torus, which seems impossible to obtain by the previous approach.     

Optimal all-to-all broadcast in WDM optical networks with breakdown or power-off transceivers

All-to-all broadcast is an interesting special case of the packet transmission scheduling in which every pair of nodes has exactly one packet to be transferred. This paper considers the all-to-all broadcast problem in wavelength division multiplexed (WDM) optical star network with some breakdown or power-off transceivers. For reaching high data transmission rates, we will focus the problem on the all-optical scheduling where the traffic reaches its destination in single-hop without being converted to electronic form. Each transmitter is tunable with an associated tuning delay and each receiver is fixed-tuned to one of available wavelengths. In this model, we study two kinds of all-to-all broadcast problems depending on whether each node transmits packets to all nodes including or except itself. We identify the lower bound of the scheduling length for each kind of problems and propose single-hop scheduling algorithms to find the optimal solution in both terms of arbitrary number of wavelengths and value of tuning latency.     

On exploring inter-iteration parallelism within rate-balanced multirate multidimensional DSP algorithms

Although the notion of the parallelism in multidimensional applications has existed for a long time, it is so far unknown what the bound (if any) of inter-iteration parallelism in multirate multidimensional digital signal processing (DSP) algorithms is, and whether the maximum inter-iteration parallelism can be achieved for arbitrary multirate data flow algorithms. This paper explores the bound of inter-iteration parallelism within rate-balanced multirate multidimensional DSP algorithms and proves that this parallelism can always be achieved in hardware system given the availability of a large number of processors and the interconnections between them.     

Efficient scheduling of transmissions in optical broadcast networks

All-optical networks (AONs) with a broadcast-star based physical topology offer the possibility of transmission scheduling to resolve channel and receiver conflicts. This paper considers the problem of scheduling packet transmissions in a wavelength-division multiplexed (WDM) optical network with tunable transmitters and fixed-tuned receivers. The scheduling problem is complicated by tuning latency, a limited number of channels, and arbitrary traffic demands. We first analyze scheduling all-to-all packet transmissions and obtain a new lower bound for the schedule length. The lower bound is achieved by an algorithm proposed by Pieris and Sasaki (1994). We then extend the analysis to the case of arbitrary traffic demands and obtain lower bounds for the schedule length. Two constructions for scheduling algorithms are provided through list scheduling and multigraphs. The upper bounds so obtained not only provide performance guarantees with arbitrary demands, but also nearly meet the lower bound in simulations     

Digital reconstruction of multidimensional signals from their projections

In a wide variety of applications it is necessary to infer the structure of a multidimensional object from a set of its projections. There has been a long-standing interest in this problem and a number of different techniques have been proposed. In this paper, we present a tutorial review of the reconstruction problem and some of the algorithms which have been proposed for its solution. In addition, we present a number of new algorithms that appear to have some advantages over previous algorithms. Some comparisons of these algorithms applied to reconstructions of two-dimensional pictures are given. Furthermore, a number of new theoretical results are presented relating to the minimum number of projections necessary for exact reconstruction.     

协作通信网络中的合作编码技术

未来觅带无线通信系统要支持高达1 Gb／s的峰值无线传输速率,就必须考虑利用协作通信技术,充分复用频率、时间、空间等多维资源,改善网络覆盖性能。合作编码将协作信号处理和信道编码技术有机地结合在一起,是实现高性能合作通信的重要保障,合作编码将成为未来觅带无线通信技术的一项关键技术。合作编码技术必须适应节点的双工或半双工通信方式,采用适应不同的协同通信网络环境要求的合作编码技术方案。未来的合作编码技术的发展方向是自适应的合作编码技术和网络编码协作技术。