具有自适应能力的Epidemic路由算法

Epidemic算法在某些场景中具有很高的传输成功率、很小的传输延迟,但其适应性较差,在另一些场景中性能会显著下降。分析了影响Epidemic算法性能的因素,认为挤出效应是导致算法性能下降的主要原因;提出了A-daptive机制,其使节点可以根据周围节点缓存的状况调整注入网络数据包的数量,主动地抑制挤出效应的发生,进而改善Epidemic算法性能。仿真结果表明,改进后算法的传输成功率显著提高,路由开销大幅度下降。     

一种通孔最小化的三层通道布线算法

本文提出的连通孔最小化的三层通道布线算法,根据线网的接点位置建立线网分层图,并对此图进行三着色,确定出初始布线集和分拆线网集,通过引进线网次序图、压缩空段长度、填充原则和逐步排障法等,将初始布线集和拆网集的线网分配到相应的走线道上.实现线网的互连.本算法已用PASCAL语言编程,并在XT/286机上实现.结果表明,该算法不仅使通孔数大大减少,而且有些例子的走线道数也较一般布线法少.     

Branch pipe routing based on 3D connection graph and concurrent ant colony optimization algorithm

Pipe routing, in particular branch pipes with multiple terminals, has an important influence on product performance and reliability. This paper develops a new rectilinear branch pipe routing approach for automatic generation of the optimal rectilinear branch pipe routes in constrained spaces. Firstly, this paper presents a new 3D connection graph, which is constructed by extending a new 2D connection graph. The new 2D connection graph is constructed according to five criteria in discrete Manhattan spaces. The 3D connection graph can model the 3D constrained layout space efficiently. The length of pipelines and the number of bends are modeled as the optimal design goal considering the number of branch points and three types of engineering constraints. Three types of engineering constraints are modeled by this 3D graph and potential value. Secondly, a new concurrent Max–Min Ant System optimization algorithm, which adopts concurrent search strategy and dynamic update mechanism, is used to solve Rectilinear Branch Pipe Routing optimization problem. This algorithm can improve the search efficiency in 3D constrained layout space. Numerical comparisons with other current approaches in literatures demonstrate the efficiency and effectiveness of the proposed approach. Finally, a case study of pipe routing for aero-engines is conducted to validate this approach.     

基于历史效用的机会网络路由算法

针对机会网络中传统的概率路由协议投递率较低的问题,提出一种基于历史相遇预测的改进概率路由(HMPR)算法。该算法根据节点历史接触时间和接触频率两个因素,预测数据包成功投递到目的节点的效用值,通过比较其效用值大小来决定数据包是否转发到下一跳节点。仿真结果表明,与传统的传染路由和概率路由相比,该路由在数据包投递率、平均延迟时间和平均缓存时间方面比上述两个路由协议的性能更好。     

一种自适应多层无网格布线算法

为适应多布线层，采用非均匀网格图模型，引入了一种自适应迭代策略，将多层布线转化为多次两层布线来处理，既能适应任意布线层数，又大大减少了多层迷宫布线的搜索空间；针对非均匀网格图模型的特点，提出了优化的绕障长度的迷宫布线算法。实验数据显示算法具有较快的搜索速度和较好的布线质量。     

A variable neighborhood search algorithm for the optimization of a dial-a-ride problem in a large city

On-demand transportation is becoming a new necessary service for modern (public and private) mobility and logistics providers. Large cities are demanding more and more share transportation services with flexible routes, resulting from user dynamic demands. In this study a new algorithm is proposed for solving the problem of computing the best routes that a public transportation company could offer to satisfy a number of customer requests. In this problem, known in the literature as the dial-a-ride problem, a number of passengers has to be transported between pickup and delivery locations trying to minimize the routing costs while respecting a set of pre-specified constraints (maximum pickup time, maximum ride duration and maximum load per vehicle). For optimizing this problem, a new variable neighborhood search has been developed and tested on a set of 24 different scenarios of a large-scale dial-a-ride problem in the city of San Francisco. The results have been compared against two state-of-the-art algorithms of the literature and validated by means of statistical procedures proving that the new algorithm has obtained the best overall results.     

星形图上无死锁的路径算法

星形图具有许多良好的拓扑性质，是一种有可能替代传统的超立方体的并行计算互联网络的模型。在本文中，作者针对在星形图这样一种高度规则的网络中，可能产生死锁的问题，对星形图上无死锁的路径算法进行了研究。首先利用星形图中匹配基的性质，给出了从Ｓｎ（Ｂ）到Ｓｋ的正规映射的定义，然后提出了星形图上的两个无死锁受限条件，最后证明了一个满足无死锁受限条件的路径算法。作者还提出了星形图上路径算法的最小无死锁受限条件     

具有退避机制的Epidemic路由算法

Epidemic算法在某些场景中具有很高的传输成功率、很小的传输延迟,但算法的适应性较差,在另一些场景中算法性能会显著下降。理论和实验分析表明,挤出效应是导致Epidemic算法性能下降的主要原因。分析了具有免疫机制Epidemic算法的性能,指出了该机制的缺陷,提出了退避机制:当某一节点缓冲区饱和时,不再接收与之相遇节点的数据包。在ONE仿真平台上实现了具有退避机制的Ep-idemic算法,实验结果表明,在挤出效应显著的场景下,退避机制能有效地抑制挤出效应,改进后算法的传输成功率有大幅度的提高,路由开销也有一定程度的下降。     

Scalable Routing in Cyclic Mobile Networks

The nonexistence of an end-to-end path poses a challenge in adapting traditional routing algorithms to delay-tolerant networks (DTNs). Previous works have covered centralized routing approaches based on deterministic mobility, ferry-based routing with deterministic or semideterministic mobility, flooding-based approaches for networks with general mobility, and probability-based routing for semideterministic mobility models. Unfortunately, none of these methods can guarantee both scalability and delivery. In this paper, we extend the investigation of scalable deterministic routing in DTNs with repetitive mobility based on our previous works. Instead of routing with global contact knowledge, we propose a routing algorithm that routes on contact information compressed by three combined methods. We address the challenge of efficient information aggregation and compression in the time-space domain while maintaining critical information for efficient routing. Then, we extend it to handle a moderate level of uncertainty in contact prediction. Analytical studies and simulation results show that the performance of our proposed routing algorithm, DTN Hierarchical Routing (DHR), is comparable to that of the optimal time-space Dijkstra algorithm in terms of delay and hop count. At the same time, the per-node storage overhead is substantially reduced and becomes scalable.     

Localized Delaunay triangulation with application in ad hoc wireless networks

Several localized routing protocols guarantee the delivery of the packets when the underlying network topology is a planar graph. Typically, relative neighborhood graph (RING) or Gabriel graph (GG) is used as such planar structure. However, it is well-known that the spanning ratios of these two graphs are not bounded by any constant (even for uniform randomly distributed points). Bose et al. (1999) recently developed a localized routing protocol that guarantees that the distance traveled by the packets is within a constant factor of the minimum if Delaunay triangulation of all wireless nodes is used, in addition, to guarantee the delivery of the packets. However, it is expensive to construct the Delaunay triangulation in a distributed manner. Given a set of wireless nodes, we model the network as a unit-disk graph (UDG), in which a link uv exists only if the distance /spl par/uv/spl par/ is at most the maximum transmission range. In this paper, we present a novel localized networking protocol that constructs a planar 2 5-spanner of UDG, called the localized Delaunay triangulation (LDEL), as network topology. It contains all edges that are both in the unit-disk graph and the Delaunay triangulation of all nodes. The total communication cost of our networking protocol is O(n log n) bits, which is within a constant factor of the optimum to construct any structure in a distributed manner. Our experiments show that the delivery rates of some of the existing localized routing protocols are increased when localized Delaunay triangulation is used instead of several previously proposed topologies. Our simulations also show that the traveled distance of the packets is significantly less when the FACE routing algorithm is applied on LDEL, rather than applied on GG.     

三维空间中LEACH协议的改进算法

由于传感器节点的能量有限,因此能量效率是无线传感器网络中路由协议设计的一个重要考虑方面.基于高楼三维空间中家居监测的应用背景,提出了一种三维空间中LEACH协议的改进算法--三维分簇传感网络路由协议(3D-CSR).3D-CSR采用考虑节点剩余能量因素的簇头选举阈值计算方法,并使用了合适的通信模式,达到节省网络能量消耗的目的.仿真结果表明,在不同的网络环境中,3D-CSR协议均比LEACH协议更加节省能量.     

一种联合多信道分配决策的认知Mesh系统数据传输优化算法

在认知Mesh系统进行数据传输的过程中,为了提高数据包投递成功率及网络的吞吐量,减少网络延迟时间,提出一种联合多信道分配决策的认知Mesh系统数据传输优化算法(JCWN)。针对信道的干扰问题,建立了认知Mesh系统的干扰无向图,分析节点链路的网络干扰电平。在节点的路由请求阶段通过提出基于信道干扰电平的路由指标函数,并通过权重阈值来为节点链路分配干扰较小的信道。在路由选择上,联合多路由算法计算每条路由路径的信道干扰程度,为了保障节点传输数据的成功率而选择干扰程度更小的路由。实验仿真结果表明,在数据包投递成功率上,该算法相比POC算法以及基于RL的算法提高了20%以上,在提高网络吞吐量,减少延迟时间上也表现出了更好地效果。     

基于残差图卷积网络与深度强化学习的 需求可拆分车辆路径优化算法

需求可拆分车辆路径问题(SDVRP)出现在广泛的物流配送场景中, 具有重要的研究价值. 高效的SDVRP优化算法能够提高车辆装载率, 降低物流配送成本. 为提高SDVRP的求解效率, 本文提出基于残差图卷积神经网络(RGCN)和多头注意力的深度强化学习算法(REINFORCE), 逐步构建可行解序列. 首先, 从强化学习的角度出发, 文章对SDVRP建立马尔科夫决策模型, 定义序列预测过程的环境状态、智能体动作空间、状态转移函数等. 其次, 建立编–解码模型求解节点选择策略, 其中使用残差图卷积神经网络的编码器重构配送中心和客户节点的特征, 将配送网络中节点间的连接关系与节点特征相互关联, 获得差异性显著的特征嵌入向量; 利用注意力网络解码器在重构后的嵌入向量基础上融合动态变化的车辆剩余装载量和客户需求等信息执行解码任务, 实现每次迭代为单个案例提供多个可行解. 最后, 提出基于平均基准值的REINFORCE算法更新模型参数, 通过求解不同问题规模测试集、标准SDVRP数据集, 以及京东物流实际配送任务, 验证了所提算法的有效性.     

Making-a-stop: A new bufferless routing algorithm for on-chip network

In the deep submicron regime, the power and area consumed by router buffers in network-on-chip (NoC) have become a primary concern. With buffers elimination, bufferless routing is emerging as a promising solution to provide power-and-area efficiency for NoC. In this paper, we present a new bufferless routing algorithm that can be coupled with any topology. The proposed routing algorithm is based on the concept of making-a-stop (MaS), aiming to deadlock and livelock freedom in wormhole-switched NoC. Performance evaluation is carried out by using a flit-level, cycle-accurate network simulator under synthetic traffic scenarios. Simulation results indicate that the proposed routing algorithm yields an improvement over the recent bufferless routing algorithm in average latency, power consumption, and area overhead by up to 10%, 9%, and 80%, respectively.     

IEH graphs

We propose a new family of interconnection topology that can be used to design communication architecture for distributed systems with an arbitrary number of computing nodes. The design is based on a novel generalization of the well known hypercube graphs. The proposed topology is shown to be incrementally extensible in steps of 1 (cost of restructuring or adding edges is very low), optimally fault tolerant and its diameter is logarithmic in the number of nodes. Moreover, for any given number of nodes, the difference of the maximum and the minimum degree of a node in the graph is ≤1, i.e., the graph is almost regular. A shortest routing algorithm for the proposed family of graphs has been developed.     

Cost‐effective queue schemes for reducing head‐of‐line blocking in fat‐trees

The fat‐tree is one of the most common topologies among the interconnection networks of the systems currently used for high‐performance parallel computing. Among other advantages, fat‐trees allow the use of simple but very efficient routing schemes. One of them is a deterministic routing algorithm that has been recently proposed, offering a similar (or better) performance than adaptive routing while reducing complexity and guaranteeing in‐order packet delivery. However, as other deterministic routing proposals, this deterministic routing algorithm cannot react when high traffic loads or hot‐spot traffic scenarios produce severe contention for the use of network resources, leading to the appearance of Head‐of‐Line (HoL) blocking, which spoils the network performance. In that sense, we describe in this paper two simple, cost‐effective strategies for dealing with the HoL‐blocking problem that may appear in fat‐trees with the aforementioned deterministic routing algorithm. From the results presented in the paper, we conclude that, in the mentioned environment, these proposals considerably reduce HoL‐blocking without significantly increasing switch complexity and the required silicon area. Copyright © 2011 John Wiley & Sons, Ltd.     

延迟容忍网络中基于概率传递的可靠路由算法

针对延迟容忍网络中节点缓存受限引起大量消息被丢弃的问题,在概率路由算法的基础上,提出一种基于概率传递的可靠路由算法R PROPHET。该路由算法根据节点缓存中消息替换的历史情况评价节点的可靠性,以保证消息在可靠的节点间传输直至交付给目的节点。仿真结果表明,该算法能够减轻消息在节点间无效传递的情况,能够获得较高的消息交付率,并具有较低的通信开销。     

泛洪攻击下机会网络典型路由算法健壮性分析

设计了评价方法及指标体系,通过对真实城市场景中带有智能蓝牙设备行人移动行为的仿真,从传输能力、传输效率和节点能耗三个方面定量分析了志愿节点的作用以及在有或没有志愿节点参与情况下泛洪攻击的效果,以此来评价Direct Delivery、Epidemic、Spray and Wait、Prophet和MaxProp共五种机会网络典型路由算法在泛洪攻击下的健壮性。结果表明Direct Delivery算法健壮性最好,能完全抵御泛洪攻击,Spray and Wait算法的健壮性最差,在某些场景下性能会下降80%以上,其他三种算法在泛洪攻击下性能会显著下降。     

无线传感mesh网络的分段地址分配策略及其路由

无线传感器网络中的设备具有能量、缓存空间、通信和计算能力受限的特点。因此,无线传感器网络路由算法需要具备低存储开销、低计算复杂度、无路由发现等特征。HiLow是一种分层路由协议,它完全符合上述特点,且比IEEE 802.15.5具有更好的路由特性。但HiLow存在一些不足,如地址利用率低、仅适用于小规模网络等,无法应用于如环境监测、动物保护等具有较多节点数量和较大网络规模的应用场景。提出了一种两段地址分配策略TFA,它将16位地址分成两段,前段地址用于全功能设备的地址分配,后段地址用于精简功能设备的地址分配。理论分析和数值仿真显示, 相比于HiLow,TFA具有更大的地址利用率和路由树最大深度,能够适用于更大规模的无线传感网络。分析了TFA的mesh路由优化特性,提出了基于TFA的mesh路由算法。仿真结果表明,基于TFA的mesh路由在存储空间使用和能耗等方面都优于IEEE 802.15.5。     

路标迭代提取和剔除的自适应空洞处理算法

针对无线传感器网络贪婪地理路由协议中的路由空洞问题,提出一种高效的基于路标迭代提取和剔除的自适应空洞处理算法.该算法中,当探测包贪婪转发遇到空洞时,在网络拓扑局部平面化的基础上,以左(右)手法则提取空洞边界并沿其逆(顺)时针周边模式双向转发,同时,分布式地进行路标的迭代提取和剔除,直到获取的路标使得后续的数据包依次以它们为中间目标节点进行传输而不再遇到空洞为止.仿真结果表明,该协议能够以较小的控制开销代价获得次最优的传输路径,极大地提高了路由协议的性能,可以应用于无法消除路由空洞的大规模无线传感器网络贪婪地理路由协议.