Showing papers on "Routing (electronic design automation) published in 2009"

Encounter: based routing in DTNs

Abstract: Current work in routing protocols for delay and disruption tolerant networks leverage epidemic-style algorithms that trade off injecting many copies of messages into the network for increased probability of message delivery. However, such techniques can cause a large amount of contention in the network, increase overall delays, and drain each mobile node’s limited battery supply. We present a new DTN routing algorithm, called Encounter-Based Routing (EBR), which maximizes delivery ratios while minimizing overhead and delay. Furthermore, we present a means of securing EBR against black hole denialof-service attacks. EBR achieves up to a 40% improvement in message delivery over the current state-of-the-art, as well as achieving up to a 145% increase in goodput. Also, we further show how EBR outperforms other protocols by introduce three new composite metrics that better characterize DTN routing performance.

Encounter-Based Routing in DTNs

Abstract: Current work in routing protocols for delay and disruption tolerant networks leverage epidemic-style algorithms that trade off injecting many copies of messages into the network for increased probability of message delivery. However, such techniques can cause a large amount of contention in the network, increase overall delays, and drain each mobile node's limited battery supply. We present a new DTN routing algorithm, called Encounter-Based Routing (EBR), which maximizes delivery ratios while minimizing overhead and delay. Furthermore, we present a means of securing EBR against black hole denial- of-service attacks. EBR achieves up to a 40% improvement in message delivery over the current state-of-the-art, as well as achieving up to a 145% increase in goodput. Also, we further show how EBR outperforms other protocols by introduce three new composite metrics that better characterize DTN routing performance.

A unified exact method for solving different classes of vehicle routing problems

Abstract: This paper presents a unified exact method for solving an extended model of the well-known Capacitated Vehicle Routing Problem (CVRP), called the Heterogenous Vehicle Routing Problem (HVRP), where a mixed fleet of vehicles having different capacities, routing and fixed costs is used to supply a set of customers. The HVRP model considered in this paper contains as special cases: the Single Depot CVRP, all variants of the HVRP presented in the literature, the Site-Dependent Vehicle Routing Problem (SDVRP) and the Multi-Depot Vehicle Routing Problem (MDVRP). This paper presents an exact algorithm for the HVRP based on the set partitioning formulation. The exact algorithm uses three types of bounding procedures based on the LP-relaxation and on the Lagrangean relaxation of the mathematical formulation. The bounding procedures allow to reduce the number of variables of the formulation so that the resulting problem can be solved by an integer linear programming solver. Extensive computational results over the main instances from the literature of the different variants of HVRPs, SDVRP and MDVRP show that the proposed lower bound is superior to the ones presented in the literature and that the exact algorithm can solve, for the first time ever, several test instances of all problem types considered.

Routing Requirements for Urban Low-Power and Lossy Networks

Abstract: The application-specific routing requirements for Urban Low Power and Lossy Networks (U-LLNs) are presented in this document. In the near future, sensing and actuating nodes will be placed outdoors in urban environments so as to improve the people's living conditions as well as to monitor compliance with increasingly strict environmental laws. These field nodes are expected to measure and report a wide gamut of data, such as required in smart metering, waste disposal, meteorological, pollution and allergy reporting applications. The majority of these nodes is expected to communicate wirelessly which - given the limited radio range and the large number of nodes - requires the use of suitable routing protocols. The design of such protocols will be mainly impacted by the limited resources of the nodes (memory, processing power, battery, etc.) and the particularities of the outdoor urban application scenarios. As such, for a wireless Routing Over Low power and Lossy networks (ROLL) solution to be useful, the protocol(s) ought to be energy-efficient, scalable, and autonomous. This documents aims to specify a set of requirements reflecting these and further U-LLNs tailored characteristics.

Vehicle routing with cross-docking

Abstract: Over the past decade, cross-docking has emerged as an important material handling technology in transportation. A variation of the well-known Vehicle Routing Problem (VRP), the VRP with Cross-Docking (VRPCD) arises in a number of logistics planning contexts. This paper addresses the VRPCD, where a set of homogeneous vehicles are used to transport orders from the suppliers to the corresponding customers via a cross-dock. The orders can be consolidated at the cross-dock but cannot be stored for very long because the cross-dock does not have long-term inventory-holding capabilities. The objective of the VRPCD is to minimize the total travel time while respecting time window constraints at the nodes and a time horizon for the whole transportation operation. In this paper, a mixed integer programming formulation for the VRPCD is proposed. A tabu search heuristic is embedded within an adaptive memory procedure to solve the problem. The proposed algorithm is implemented and tested on data sets provided by the Danish consultancy Transvision, and involving up to 200 pairs of nodes. Experimental results show that this algorithm can produce high-quality solutions (less than 5% away from optimal solution values) within very short computational time.

Integrated Circuit Devices and Methods and Apparatuses for Designing Integrated Circuit Devices

Abstract: Methods and apparatuses to design an Integrated Circuit (IC) with a shielding of wires. In at least one embodiment, a shielding mesh of at least two reference voltages (e.g., power and ground) is used to reduce both the capacitive coupling and the inductive coupling in routed signal wires in IC chips. In some embodiments, a type of shielding mesh (e.g., a shielding mesh with a window surrounded by a power ring, or a window with a parser set of shielding wires) is selected to make more routing area available in locally congested areas. In other embodiments, the shielding mesh is used to create or add bypass capacitance. Other embodiments are also disclosed.

Static and dynamic wavelength routing via the gradient optical force

Abstract: We propose and demonstrate an all-optical wavelength routing approach that uses a tuning mechanism based upon the optical gradient force in a specially designed nano-optomechanical system. The resulting mechanically compliant 'spiderweb' resonator realizes seamless wavelength routing over a range of 3,000 times the intrinsic channel width, with a tuning efficiency of 309 GHz mW^(-1), a switching time of less than 200 ns, and 100% channel quality preservation over the entire tuning range. These results indicate the potential for radiation pressure actuated devices to be used in a variety of photonics applications, such as channel routing/switching, buffering, dispersion compensation, pulse trapping/release and widely tunable lasers.

The integrated production---inventory---distribution---routing problem

Abstract: The integration of production and distribution decisions presents a challenging problem for manufacturers trying to optimize their supply chain. At the planning level, the immediate goal is to coordinate production, inventory, and delivery to meet customer demand so that the corresponding costs are minimized. Achieving this goal provides the foundations for streamlining the logistics network and for integrating other operational and financial components of the system. In this paper, a model is presented that includes a single production facility, a set of customers with time varying demand, a finite planning horizon, and a fleet of vehicles for making the deliveries. Demand can be satisfied from either inventory held at the customer sites or from daily product distribution. In the most restrictive case, a vehicle routing problem must be solved for each time period. The decision to visit a customer on a particular day could be to restock inventory, meet that day's demand or both. In a less restrictive case, the routing component of the model is replaced with an allocation component only. A procedure centering on reactive tabu search is developed for solving the full problem. After a solution is found, path relinking is applied to improve the results. A novel feature of the methodology is the use of an allocation model in the form of a mixed integer program to find good feasible solutions that serve as starting points for the tabu search. Lower bounds on the optimum are obtained by solving a modified version of the allocation model. Computational testing on a set of 90 benchmark instances with up to 200 customers and 20 time periods demonstrates the effectiveness of the approach. In all cases, improvements ranging from 10---20% were realized when compared to those obtained from an existing greedy randomized adaptive search procedure (GRASP). This often came at a three- to five-fold increase in runtime, however.

Cross-Layer Support for Energy Efficient Routing in Wireless Sensor Networks

Abstract: The Dynamic Source Routing (DSR) algorithm computes a new route when packet loss occurs. DSR does not have an in-built mechanism to determine whether the packet loss was the result of congestion or node failure causing DSR to compute a new route. This leads to inefficient energy utilization when DSR is used in wireless sensor networks. In this work, we exploit cross-layer optimization techniques that extend DSR to improve its routing energy efficiency by minimizing the frequency of recomputed routes. Our proposed approach enables DSR to initiate a route discovery only when link failure occurs. We conducted extensive simulations to evaluate the performance of our proposed cross-layer DSR routing protocol. The simulation results obtained with our extended DSR routing protocol show that the frequency with which new routes are recomputed is 50% lower compared with the traditional DSR protocol. This improvement is attributed to the fact that, with our proposed cross-layer DSR, we distinguish between congestion and link failure conditions, and new routes are recalculated only for the latter.

On the interplay between routing and signal representation for Compressive Sensing in wireless sensor networks

Abstract: Compressive Sensing (CS) shows high promise for fully distributed compression in wireless sensor networks (WSNs). In theory, CS allows the approximation of the readings from a sensor field with excellent accuracy, while collecting only a small fraction of them at a data gathering point. However, the conditions under which CS performs well are not necessarily met in practice. CS requires a suitable transformation that makes the signal sparse in its domain. Also, the transformation of the data given by the routing protocol and network topology and the sparse representation of the signal have to be incoherent, which is not straightforward to achieve in real networks. In this work we address the data gathering problem in WSNs, where routing is used in conjunction with CS to transport random projections of the data.We analyze synthetic and real data sets and compare the results against those of random sampling. In doing so, we consider a number of popular transformations and we find that, with real data sets, none of them are able to sparsify the data while being at the same time incoherent with respect to the routing matrix. The obtained performance is thus not as good as expected and finding a suitable transformation with good sparsification and incoherence properties remains an open problem for data gathering in static WSNs.

Static and dynamic wavelength routing via the gradient optical force

Abstract: Here we propose and demonstrate an all-optical wavelength-routing approach which uses a tuning mechanism based upon the optical gradient force in a specially-designed nano-optomechanical system. The resulting mechanically-compliant "spiderweb" resonantor realizes seamless wavelength routing over a range of 3000 times the intrinsic channel width, with a tuning efficiency of 309-GHz/mW, a switching time of less than 200-ns, and 100% channel-quality preservation over the entire tuning range. These results indicate the potential for radiation pressure actuated devices to be used in a variety of photonics applications, such as channel routing/switching, buffering, dispersion compensation, pulse trapping/release, and widely tunable lasers.

LISP Alternative Topology (LISP+ALT)

Abstract: This document describes a method of building an alternative, logical topology for managing Endpoint Identifier to Routing Locator mappings using the Locator/ID Separation Protocol. The logical network is built as an overlay on the public Internet using existing technologies and tools, specifically the Border Gateway Protocol and the Generic Routing Encapsulation. An important design goal for LISP+ALT is to allow for the relatively easy deployment of an efficient mapping system while minimizing changes to existing hardware and software.

An effective genetic algorithm for the fleet size and mix vehicle routing problems

Abstract: This paper studies the fleet size and mix vehicle routing problem (FSMVRP), in which the fleet is heterogeneous and its composition to be determined. We design and implement a genetic algorithm (GA) based heuristic. On a set of twenty benchmark problems it reaches the best-known solution 14 times and finds one new best solution. It also provides a competitive performance in terms of average solution.

Fuel efficient routing

Abstract: Techniques are described to determine a fuel-efficient route for a vehicle. In an implementation, a determination is made, based on the one or more characteristics of the vehicle, as to a route between an identified location and a designated location that would cause the vehicle to consume a lesser amount of fuel when traveling between the identified and designated locations. Accordingly, the route may be represented, such as for use in navigating to the designated location.

A hybrid metaheuristic algorithm for the vehicle routing problem with simultaneous delivery and pick-up service

Abstract: This article addresses a vehicle routing problem variant which considers customers to require simultaneous delivery and pick-up service (VRPSPD). The objective of this problem is to determine the optimal set of routes to totally satisfy both the delivery and pick-up demand of the customer population. VRPSPD is an NP-hard combinatorial optimization problem; therefore exact methods are incapable of dealing with large scale VRPSPD instances arising in a wide variety of practical operations. We propose a hybrid solution approach incorporating the rationale of two well-known metaheuristics which have proven to be effective for routing problem variants, namely tabu search and guided local search. The intelligence of the proposed hybrid was designed to achieve a vast exploration of the search space, by escaping from local optima and intensifying at promising solution regions. The performance of our metaheuristic algorithm was tested on benchmark instances involving from 50 to 400 customers. It produced high quality results, improving several best solutions previously reported.

Multiple routing configurations for fast IP network recovery

Abstract: As the Internet takes an increasingly central role in our communications infrastructure, the slow convergence of routing protocols after a network failure becomes a growing problem. To assure fast recovery from link and node failures in IP networks, we present a new recovery scheme called Multiple Routing Configurations (MRC). Our proposed scheme guarantees recovery in all single failure scenarios, using a single mechanism to handle both link and node failures, and without knowing the root cause of the failure. MRC is strictly connectionless, and assumes only destination based hop-by-hop forwarding. MRC is based on keeping additional routing information in the routers, and allows packet forwarding to continue on an alternative output link immediately after the detection of a failure. It can be implemented with only minor changes to existing solutions. In this paper we present MRC, and analyze its performance with respect to scalability, backup path lengths, and load distribution after a failure. We also show how an estimate of the traffic demands in the network can be used to improve the distribution of the recovered traffic, and thus reduce the chances of congestion when MRC is used.

Test architecture design and optimization for three-dimensional SoCs

Abstract: Core-based system-on-chips (SoCs) fabricated on three-dimensional (3D) technology are emerging for better integration capabilities. Effective test architecture design and optimization techniques are essential to minimize the manufacturing cost for such giga-scale integrated circuits. In this paper, we propose novel test solutions for 3D SoCs manufactured with die-to-wafer and die-to-die bonding techniques. Both testing time and routing cost associated with the test access mechanisms in 3D SoCs are considered in our simulated annealing-based technique. Experimental results on ITC'02 SoC benchmark circuits are compared to those obtained with two baseline solutions, which show the effectiveness of the proposed technique.

Unifying Packet and Circuit Switched Networks

Abstract: There have been many attempts to unify the control and management of circuit and packet switched networks, but none have taken hold. In this paper we propose a simple way to unify both types of network using OpenFlow. The basic idea is that a simple flow abstraction fits well with both types of network, provides a common paradigm for control, and makes it easy to insert new functionality into the network. OpenFlow provides a common API to the underlying hardware, and allows all of the routing, control and management to be defined in software outside the datapath.

Traffic localization for P2P-applications: The ALTO approach

Abstract: Today, most P2P applications do not consider locality on the underlying network topology when choosing their neighbors on the P2P routing layer. As a result, participating peers may experience long delays and peers' ISPs suffer from a large amount of (costly) inter-ISP traffic. One potential solution to mitigate these problems is to have ISPs or third parties convey information regarding the underlying network topology to P2P-clients through a dedicated service. Following this approach, the IETF has recently formed an Application Layer Traffic Optimization (ALTO) working group for standardizing a protocol to enable P2P applications to obtain information regarding network layer topology. This paper comprises the problem space for such an ALTO approach, taking into account recent developments in the IETF ALTO Working Group. In particular, we will describe requirements for an ALTO protocol identified in the IETF, concrete protocols which have been proposed so far, and the overall challenges. In addition, we will discuss related issues such as privacy considerations, the relationship of an ALTO service with existing caching solutions, discovery mechanisms for an ALTO service, and security considerations.

Semiconductor die including a current routing line having non-metallic slots

Abstract: A semiconductor die that includes a plurality of non-metallic slots that extend through a current routing line is disclosed. The semiconductor die comprises a semiconductor circuit that includes a plurality of semiconductor components and a current trace line that is coupled to a first semiconductor component. Further, the semiconductor die comprises a current routing line that is coupled with the current trace line. The current routing line includes a plurality of non-metallic slots that extend through the current routing line.