Priority-Based Routing Resource Assignment Considering Crosstalk

Crosstalk has become one of the most critical concerns in very deep sub-micron era. This paper deals with the problem of crosstalk mitigation at both methodological and algorithmic levels. Noting that intermediate operations between global routing and detailed routing are very effective in crosstalk estimation and reduction, the authors propose to incorporate several intermediate steps that are separated in traditional design flow into an integrated routing resource assignment stage, so that the operations could easily cooperate to fully exert their power on crosstalk reduction. An efficient priority-based heuristic algorithm is developed, which works slice by slice. Crosstalk avoidance, and many other aspects that are critical in routing practice including congestion, vias, layer preference, etc., are taken into account. A track reservation strategy is adopted in the algorithm framework to compensate the undesired effects caused by sequential routing. Experimental results on a series of ISPD98 and industrial benchmarks show that the proposed approach is able to reduce capacitive crosstalk by about 70% on average without compromising completion ratio compared with a previously reported graph based algorithm, demonstrating the advantages of the approach.     

A multipopulation parallel genetic simulated annealing-based QoS routing and wavelength assignment integration algorithm for multicast in optical networks

In this paper, we propose an integrated Quality of Service (QoS) routing algorithm for optical networks. Given a QoS multicast request and the delay interval specified by users, the proposed algorithm can find a flexible-QoS-based cost suboptimal routing tree. The algorithm first constructs the multicast tree based on the multipopulation parallel genetic simulated annealing algorithm, and then assigns wavelengths to the tree based on the wavelength graph. In the algorithm, routing and wavelength assignment are integrated into a single process. For routing, the objective is to find a cost suboptimal multicast tree. For wavelength assignment, the objective is to minimize the delay of the multicast tree, which is achieved by minimizing the number of wavelength conversion. Thus both the cost of multicast tree and the user QoS satisfaction degree can approach the optimal. Our algorithm also considers load balance. Simulation results show that the proposed algorithm is feasible and effective. We also discuss the practical realization mechanisms of the algorithm.     

一种IP／DWDM光因特网中的QoS组播路由算法

本文讨论了一种IP／DWDM光因特同的QoS组播路由算法，在已知QoS组播请求和所需时间延迟的前提下．提出了一种可以找到基于柔性QoS的、次优的路由树的算法。此外．我们对QoS满意程度一术语作了定义。所提出的算法在多种群并行遗传模拟退火算法基础上构建组播树，并根据波长图为树分配波长。此算法将路由选择和波长分配一体化，路由选择的目的在于找到一个次优组播树，波长分配的目的则是通过使波长覆盖数量最小来最小化组播树的延迟。因此，组播树的估价和QoS用户满意程度两方面都接近最优。该算法同时考虑了负载均衡。仿真结果表明．该算法是灵活有效的。     

Crosstalk-Aware Routing Resource Assignment

Crosstalk noise is one of the emerging issues in deep sub-micrometer technology which causes many undesired effects on the circuit performance. In this paper, a Crosstalk-Aware Routing Resource Assignment (CARRA) algorithm is proposed, which integrates the routing layers and tracks to address the crosstalk noise issue during the track/layer assignment stage. The CARRA problem is formulated as a weighted bipartite matching problem and solved using the linear assignment algorithm. The crosstalk risks between nets are represented by an undirected graph and the maximum number of the concurrent crosstalk risking nets is computed as the max clique of the graph. Then the nets in each max clique are assigned to disadjacent tracks. Thus the crosstalk noise can be avoided based on the clique concept. The algorithm is tested on IBM benchmarks and the experimental results show that it can improve the final routing layout a lot with little loss of the completion rate.     

A parallel genetic algorithm for performance-driven VLSI routing

This paper presents a novel approach to solve the VLSI (very large scale integration) channel and switchbox routing problems. The approach is based on a parallel genetic algorithm (PGA) that runs on a distributed network of workstations. The algorithm optimizes both physical constraints (length of nets, number of vias) and crosstalk (delay due to coupled capacitance). The parallel approach is shown to consistently perform better than a sequential genetic algorithm when applied to these routing problems. An extensive investigation of the parameters of the algorithm yields routing results that are qualitatively better or as good as the best published results. In addition, the algorithm is able to significantly reduce the occurrence of crosstalk     

A simple fault-tolerant adaptive and minimal routing approach in 3-D meshes

In this paper we propose a sufficient codition for minimal routing in 3-dimensional (3-D) meshes with faulty nodes,It is based on an early work of the author on minial routing in 2-dimensional(2-D) meshes,Unlike many traditional models that assume all the nodes know global fault distribution or just adjacent fault information,our approach is based on the concept of limited global fault information,First,we propose a fault model called faulty cube in which all faulty nodes in the system are contained in a set of faulty cubes.Fault information is then distributed to limited number of nodes while it is still sufficeint to support minimal routing.The limited fault information collcted at each node is represented by a vector caaled extended safety level.The extended safety level associated with a node can be used to determine the existence of a minimal path from this node to a given destination .Specifically,we study the existence of minimal paths at a given source node,limited distribution of fault information,minimal routing,and deadlock-free and livelock-free routing.our results show that any minimal routing that is partially adaptive can be applied in our model as long as the dstination node meets a certain conditon.We also propose a dynamic planar-adaptive routing scheme that offers better fault tolerance and adaptivity than the planar-adaptive routing scheme in 3-D meshes.Our approach is the first attempt to address adaptive and minimal routing is 3-D meshes with faulty nodes using limited fault information.     

拥挤度驱动的总体布线层分配算法

针对多层布线问题，提出以拥挤度为驱动目标，完成布线资源的合理分配，同时达到布线层资源占用少和通孔数少等优化目标的层分配算法．首先采用启发式方法获得初始分配方案，然后通过模拟退火技术优化分配结果，最后采用试探策略优化层资源占用．工业实验数据表明，该算法能够实现线网层合理分配，获得满足拥挤度的优化解．     

消除拥挤的多层总体布线新流程

提出一种在布线前进行层分配的总体布线算法,基于一个多层布线的新流程,使用包含线网所有端点的边界盒来估计线网拥挤度,并基于拥挤度均匀的目标把线网分配到不同层对上.该算法已经实现并进行了测试,实验结果证明了其有效性.     

能耗约束的无线传感器网络的目标覆盖和路由分配研究

针对现有目标覆盖算法未充分考虑能量消耗和路由分配的不足,提出一种基于目标覆盖的能耗约束路由分配算法,该算法能够确保所有目标被完全覆盖,并降低数据传输能耗。首先,通过贪婪启发式策略获取最大集合覆盖。然后在集合覆盖基础上,通过协同进化机制对网络生存周期和时延等目标进行评价。利用适应度评估、轮盘赌选择、交叉、变异和记忆等进化机制改良目标的可行解。实验结果表明,提出的算法可以降低基于路由分配的目标覆盖算法的能量消耗,延长网络生存周期,降低网络传输时延。     

An artificial neural network approach for routing in distributed computer networks

This paper presents a new approach based on the Hopfield model of artificial neural networks to solve the routing problem in a context of computer network design. The computer networks considered are packet switching networks, modeled as non-oriented graphs where nodes represent servers, hosts or switches, while bi-directional and symmetric arcs represent full duplex communication links. The proposed method is based on a network representation enabling to match each network configuration with a Hopfield neural network in order to find the best path between any node pair by minimizing an energy function. The results show that the time delay derived from flow assignment carried out by this approach is, in most cases, better than those determined using conventional routing heuristics. Therefore, this neural-network approach is suitable to be integrated into an overall topological design process of moderate-speed and high-speed networks subject to quality of service constraints as well as to changes in configuration and link costs.     

串扰最小化的网格模式下的双层通道布线

超深亚微米IC设计中互连线的串扰情况与详细布线方案和信号波形密切相关。基于这一事实，在网格模式下的通道布线算法中建立了最小化串扰的目标函数。提出获得最小化串扰布线方案的方法。与以往算法不同的是，本方法将相邻平行线间信号跳变的方式和频度作为目标函数中的影响因子。可以更准确地估计出布线区内串扰总和的大小。并且通过构造布线生成树的方法求得精简的布线方案。有效地减少了求解具有最小串扰的布线方案的计算量。     

WDM网络中实时组播的分布式优化RWA算法

在WDM网络中,由于每条链路上可用波长是动态变化的,在考虑波长转换延迟时间的条件下,实现实时组播连接的路由选择与波长分配是十分困难的。论文提出了一种用于建立实时组播连接的分布式路由选择与波长分配算法。该算法将路由选择与波长分配统一进行,大大减少连接的建立时间。组播路由算法以Prim最小生成树算法为基础,生成一棵满足给定延迟时限的最小成本树。波长分配使用最少波长转换和同一波长最长使用策略。     

WDM网络中实时组播的分布式路由与波长分配算法

在WDM网络中,由于每条链路上可用波长是动态变化的,在考虑波长转换延迟时间的条件下,实现实时组播连接的路由与波长分配是十分困难的。该文提出了一种用于建立实时组播连接的分布式路由与波长分配算法。该算法将路由与波长分配统一进行,大大减少连接的建立时间。组播路由算法以Prim最小生成树算法和K-度宽度优先搜索方法为基础,生成一棵满足给定延迟时限的最小成本树。波长分配使用最少波长转换和负载平衡策略。     

Locomotive assignment and freight train scheduling using genetic algorithms

This study considers the movement of freight trains through a passenger rail network, a common occurrence in many developing countries. Passenger trains run according to a fixed schedule while freight trains need to be accommodated and run on the same track, ensuring that they do not interfere with passenger train movements. Operationally, this requires the assignment of a locomotive to a freight rake and then creating a workable schedule. Accordingly, we propose to solve the problem in two phases. In the first phase, we assign locomotives with partial scheduling with the objectives of minimizing total deadheading time and total coupling delay. We use a genetic algorithm to find non‐dominant locomotive assignment solutions and propose a method for evaluating its performance. The solutions are then ranked using two approaches, based on the decision maker's preferences. In the second phase, we select a locomotive assignment solution based on the ranking and find the lower bound on the arrival time of freight trains at their destinations. We use a genetic algorithm again to schedule the freight trains in the passenger rail network, with prescribed locomotive assignment precedence constraints with the objective of minimizing total tardiness. Computational results confirm the efficacy of the proposed method.     

Real-time optimization flow control

In this paper, we propose a dynamic optimization approach to end-to-end flow control in data networks. The objective is to maximize the aggregate utilities of the data sources over soft transmission rate bounds and delay constraints. The network links and data sources are considered as processors of a distributed computational system that has a global objective function. The presented model works with different shapes of utility curves under the proposition of elastic data traffic. The approach relies on real-time observations of the delay as a measure of the data network congestion at the routers (network nodes). A primal–dual algorithm carried out by the data sources is used to solve the optimization problem in a decentralized manner. The calculated transmission rates are bounded and the sources are subjected to a maximum number of data packets that can be queued downstream of each transmission session. The algorithm solves for the rates without the access to any network global information while each source calculates its transmission rate that should maximize the global objective function. The calculated optimal rates conform to rate-to-queue proportionality. Finally, we present an extensive simulation results to demonstrate the reliability of the algorithm.     

基于蚂蚁算法的组播路由调度方法

探讨了在高速包交换计算机网络中,具有端到端时延及时延拦动限制的组播路由问题,并为这类问题的解决提出了一种新颖的基于蚁算法的组播路由优化方法。仿真实验结果表明,该方法不但能实现具有时延及时延拦动限制的组播路由的全局优化,而且能克服一些现有方法的不足。     

QoS multicast tree construction in IP/DWDM optical internet by bio-inspired algorithms

In this paper, two bio-inspired Quality of Service (QoS) multicast algorithms are proposed in IP over dense wavelength division multiplexing (DWDM) optical Internet. Given a QoS multicast request and the delay interval required by the application, both algorithms are able to find a flexible QoS-based cost suboptimal routing tree. They first construct the multicast trees based on ant colony optimization and artificial immune algorithm, respectively. Then a dedicated wavelength assignment algorithm is proposed to assign wavelengths to the trees aiming to minimize the delay of the wavelength conversion. In both algorithms, multicast routing and wavelength assignment are integrated into a single process. Therefore, they can find the multicast trees on which the least wavelength conversion delay is achieved. Load balance is also considered in both algorithms. Simulation results show that these two bio-inspired algorithms can construct high performance QoS routing trees for multicast applications in IP/DWDM optical Internet.     

一种基于通孔数最小化的多层通道布线算法

该文提出了一种基于通孔数量小化的多层通道布线算法，算法采用非预留层模，首先根据线网之间的位置关系利用模拟退火算法将各线网合理地分配到对应的布线层中去，然后利用遗传算法得到相关布线层中线网的最佳布线顺序向量，最的根据得到的顺序向量利用“沉积法”将各线网布于合理的通道上，该算法克服了传统通孔优化算法中原始布线对优化结果的不利影响，使通孔的优化达到很好的效果。     

WDM网络中满足延迟和延迟差约束的分布式组播路由与波长分配算法

在WDM网络中,由于每条链路上可用波长是动态变化的,在考虑波长转换延迟时间的条件下,实现实时组播连接的路由与波长分配是十分困难的。论文提出了一种用于建立满足延迟时限和延迟差要求的实时组播连接的分布式路由与波长分配算法。该算法假定每个节点没有全局路由信息,只根据关联链路的信息进行路由选择,且将路由与波长分配统一进行。组播路由算法以Prim最小生成树算法为基础,生成一棵满足给定延迟时限的最小成本树。对不满足延迟时限的目的节点,通过增加回路边构造回路再消除长延迟路径的方式,加入到组播树中。对不满足延迟差的目的节点,采用重构Steiner树的方法,使其满足延迟差的要求。波长分配使用最少波长转换和负载平衡策略。     

一种在VLSI电路物理设计中减小串扰的优化算法

通过研究调整线段和线间距对串扰的影响,提出了一种在布线时通过采线段摄动和压缩线间距的措施来减小串扰的优化算法,计算机仿真结果表明,该算法能有效地减少芯片中的串扰,此外,可预期算法应用于布线区域不规则的情形。