Abstract

We have developed a new traffic measuring tool and applied it to the real-time simulation of a network. It monitors IP traffic on an ATM link and continuously transfers the length and timestamp of each IP packet to a post-processing system. The post-processing system receives the data, estimates the cell's arrival epoch at the transmission queue of the ATM link, and simulates the queueing behavior on-line if conditions differ from those of the actual system. The measuring tool and real-time simulation rep resent a new approach to traffic engineering. A new estimation problem, the arrival sequence estimation, is shown and some algorithms are proposed and evaluated. Document type: Part of book or chapter of book

Abstract

Solving traffic congestion problems in intersections is a complex logistic problem that usually consists in building infrastructures, such as bridges, tunnels, or roundabouts, which represent the costliest solutions. Concerning the case of roundabouts, many parameters influence its performance, e.g. geometry and size. Thus, other less costlier solutions should be pondered. This paper introduces a low-cost approach to traffic intersections, by using pre-signals; and conducts simulation experiments to verify if this approach could be used to improve the performance of traffic intersections. In this sense, an agent-based traffic simulation model was developed that applies the object modelling paradigm of Simio to model the individual behaviour of vehicles. The simulation experiments results indicate that the flow of vehicles can be increased up to 20%, reducing the average queue sizes and crossing time per vehicle and saving the fuel consumed up to 64%. (undefined) info:eu-repo/semantics/publishedVersion Document type: Part of book or chapter of book

Abstract

Multiprotocol Label Switching (MPLS) is an emerging Internet technology that facilitates traffic engineering in service provider networks. This paper considers a network performance optimization problem related to traffic engineering over MPLS. We investigate the issue of dynamic partitioning of MPLS ingress traffic into several parallel Label Switched Paths (LSP). Specifically, we present a stochastic framework for the traffic partitioning problem. Within this framework, a set of parallel edge disjoint LSPs is modeled by parallel queues and a partitioning algorithm is devised for different service classes that is adaptive to the prevailing state of the network. The performance of this approach is illustrated by numerical examples. Document type: Part of book or chapter of book

Abstract

State Estimation is an intrinsic element of many network manage-ment systems, like Power Distribution Networks and Water Distribution Networks, where its implementation not only facilitates real-time online monitoring with better observability, but it also enables an advanced control with improved system security. This paper presents a new technique based on State Estimation to address some general shortcomings of the current Active Queue Management schemes such as RED and discusses potential issues in TCP networks in order to achieve better performance. Document type: Part of book or chapter of book

Abstract

The purpose of this tutorial presentation is to introduce G-Networks, or Gelenbe Networks, which are product form queueing networks which include normal or positive customers, as well as negative customers which destroy other customers, and triggers which displace other customers from one queue to another. We derive the balance equations for these models in the context of multiple customer classes, show the product form results, and exhibit the traffic equations which - in this case, contrary to BCMP and Jackson networks - are non-linear. This leads to interesting issues of existence and uniqueness of the steady-state solution. Gelenbe Network can be used to model large scale computer systems and networks in which signaling functions represented by negative customers and triggers are used to achieve flow and congestion control. Document type: Part of book or chapter of book

Abstract

This paper addresses the requirement for a congestion control mechanism, in order to efficiently handle paging traffic over cellular networks. The standard simultaneous paging approach can easily result in congestion, for relatively small values of the offered load. Instead of differentiating paging capacity based on the incoming load, this approach is more oriented towards a limited-resource system. Considering that a paging channel usually experiences high and low utilization periods, it is proposed to differentiate the paging mechanism according to the processed load. Given medium or even mild overload conditions, several forms of sequential paging substantially decrease blocking probabilities, while presenting good delay behavior. Based on a queueing analysis, we are able to quantitatively estimate potential improvements, and point out the basic points of such an adaptive scheme. Document type: Part of book or chapter of book

Abstract

Acknowledgement (ACK) filtering has been proposed as a technique to alleviate the congestion at the input of a slow channel located on the reverse path of a TCP connection. Old ACKs waiting at the input of the slow channel are erased when new ACKs are to be queued. In the literature the case of one-ACK per connection at a time has been studied. In this paper we show that this is too aggressive for short transfers where ACKs arrive in bursts due to the slow start phase, and where the TCP source needs to receive the maximum number of ACKs to increase fast its window. We study first static filtering where a certain ACK queue length is allowed. We show analytically how this length needs to be chosen. We present then some algorithms that adapt the filtering of ACKs as a function of the slow channel utilization rather than the ACK queue length. These algorithms provide a good compromise between reducing the ACK queueing delay and passing a large number of ACKs that guarantee a fast window increase. Copyright © 2003 John Wiley & Sons, Ltd. Document type: Report

Abstract

Crash reduction factors are widely used by engineers for prioritizing safety investments. Work zones are routinely analyzed by the length and duration of queues. Queue detection warning technology has been growing in availability and reliability in recent years. However, there is sparse literature on the impact of freeway queueing on crash rates. This paper analyzes three years of crash data and crowd-sourced probe vehicle data to classify crashes as being associated with queueing conditions or free flow conditions. In 2014, only 1.2% of the distanced-weighted hours of operation of Indiana interstates operated at or under 45 MPH. A three-year study on Indiana interstates indicates that commercial vehicles were involved in over 87% of back-of-queue fatal crashes compared to 39% of all fatal crashes during free flow conditions. A new measure of crash rate was developed to account for the presence and duration of queues: crashes per mile-hour of congestion. The congested crash rate on all Indiana interstates in 2014 was found to be 24 times greater than the uncongested crash rate. These data were also separated into both rural and urban categories. In rural areas, the congested crash rate is 23 times the uncongested crash rate. In urban areas, the congested crash rate is 21 times the uncongested crash rate. Queues are found to be present for five minutes or longer prior to approximately 90% of congestion crashes in 2014. Longer term, this information shows the importance in the development of technology that can warn motorists of traffic queues.

Abstract

Today, smart cities are turning to electric transport, carpooling and zero emission zones. The growing number of electric vehicles on the roads makes it increasingly necessary to have a public charging infrastructure. On the other hand, the main limitations of electric vehicles are the limited range of their batteries and their relatively long charging times. To avoid having problems to recharge, electric vehicle drivers must plan their journeys more thoroughly than others. At the goal of optimizing trip time, drivers need to automate their travel plans based on a smart charging solution, which will require the development of new Vehicle-to-Grid applications that will allow at the charging stations to dynamically interact with the vehicles. In this paper, we propose an architecture based on an algorithm allowing the management of charging plans for electric vehicles traveling on the road to their destination, in order to minimize the duration of the drivers&rsquo journey including waiting and charging times. The decision taken by the algorithm based on the exploration of the data of each public supply station according to its location, number of vehicles in the queue, number of charging sockets, and rates of service. Document type: Article