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Congestion Level (congestion + level)
Selected AbstractsGeneralized window advertising for TCP congestion control,EUROPEAN TRANSACTIONS ON TELECOMMUNICATIONS, Issue 6 2002Mario Gerla Congestion in the Internet is a major cause of network performance degradation. The Generalized Window Advertising (GWA) scheme proposed in this paper is a new approach for enhancing the congestion control properties of TCP. GWA requires only minor modifications to the existing protocol stack and is completely backward compatible, allowing GWA-hosts to interact with non-GWA hosts without modifications. GWA exploits the notion of end-host-network cooperation, with the congestion level notified from the network to end hosts. It is based on solid control theory results mat guarantee performance and stable network operation. GWA is able to avoid window oscillations and the related fluctuations in offered load and network performance. This makes it more robust to sustained network overload due to a large number of connections competing for the same bottleneck, a situation where traditional TCP implementations fail to provide satisfactory performance. GWA-TCP is compared with traditional TCP, TCP with RED and also ECN using the ns-2 simulator. Results show that in most cases GWA-TCP outperforms the traditional schemes. In particular, when compared with ECN, it provides smoother network operation and increased fairness. [source] A macroscopic traffic model for highway work zones: Formulations and numerical resultsJOURNAL OF ADVANCED TRANSPORTATION, Issue 3 2006Gang-len Chang This study presents a multilane model for analyzing the dynamic traffic properties of a highway segment under a lane-closure operation that often incurs complex interactions between mandatory lane-changing vehicles and traffic at unblocked lanes. The proposed traffic flow formulations employ the hyperbolic model used in the non-Newtonian fluid dynamics, and assume the lane-changing intensity between neighboring lanes as a function of their difference in density. The results of extensive simulation experiments indicate that the proposed model is capable of realistically replicating the impacts of lane-changing maneuvers from the blocked lanes on the overall traffic conditions, including the interrelations between the approaching flow density, the resulting congestion level, and the exiting flow rate from the lane-closure zone. Our extensive experimental analyses also confirm that traffic conditions will deteriorate dramatically and evolve to the state of traffic jam if the density has exceeded its critical level that varies with the type of lane-closure operations. This study also provides a convenient way for computing such a critical density under various lane-closure conditions, and offers a theoretical basis for understanding the formation as well as dissipation of traffic jam. [source] A Linear Model for the Continuous Network Design ProblemCOMPUTER-AIDED CIVIL AND INFRASTRUCTURE ENGINEERING, Issue 5 2006S. Travis Waller A linear programming formulation is introduced based on a dynamic traffic assignment (DTA) model that propagates traffic according to the cell transmission model. The introduced approach is limited to continuous link improvements and does not provide for new link additions. The main contribution of the article is to provide an analytical formulation for network design that accounts for DTA conditions that can be used for further analysis and extensions. The model is tested on a single destination example network, resembling a freeway corridor, for various congestion levels, loading patterns and budget sizes, to demonstrate the simplicity and effectiveness of the approach. [source] Passengers' perceptions and effects of bus-holding strategy using automatic vehicle location technologyJOURNAL OF ADVANCED TRANSPORTATION, Issue 3 2009Shinya Hanaoka This study reports bus passengers' behavior and perceptions related to the use of potential features of an automatic vehicle location (AVL) system in bus transit through conducting an attitudinal on-board survey in Bangkok. A passenger waiting-time survey conducted as part of this study revealed that passengers perceive waiting-time at bus stops to be greater than actually experienced. The other aim of this study is to examine the potential benefits of bus-holding using an AVL technology, in terms of waiting-time, through minimizing bus bunching under different congestion levels. The results are obtained using PARAMICS, and reveal a significant reduction in average waiting-time. [source] | ||||||||||