Véhicules et Injustice...Quand l’Anarchie renverse le pouvoir local: Présentation d'un algorithme distribué, convergeant, équitable et efficace pour VANETs.

Les réseaux véhiculaires ad hoc (VANETs) désignent des réseaux composés de véhicules qui communiquent via des technologies de communication hétérogènes dans des conditions de grande mobilité. Le choix de la technologie de communication et le choix du chemin se révèlent primordiaux pour des communications multisauts. L'objectif choisi dans ce papier est de maximiser la quantité d'informationéchangéeinformation´informationéchangée. L'algorithme distribué multiflots asynchrone proposé permetàpermet`permetà la fois la sélection de la technologie de communication et du noeud voisin (routage). Sa modélisation sous la forme d'un jeu de congestion non-coopératif permet de prouver sa convergence vers unéquilibreun´unéquilibre de Nash. Ses propriétés d'´ equité et d'efficacité sont finalement démontrées grâcè a l'optimum de Pareto et au prix de l'anarchie

doi:10.1155/2012/492105 Research Article A Semi-Deterministic Channel Model for VANETs Simulations

Copyright © 2012 Jonathan Ledy et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Today’s advanced simulators facilitate thorough studies on Vehicular Ad hoc NETworks (VANETs). However the choice of the physical layer model in such simulators is a crucial issue that impacts the results. A solution to this challenge might be found with a hybrid model. In this paper, we propose a semi-deterministic channel propagation model for VANETs called UM-CRT. It is based on CRT (Communication Ray Tracer) and SCME—UM (Spatial Channel Model Extended—Urban Micro) which are, respectively, a deterministic channel simulator and a statistical channel model. It uses a process which adjusts the statistical model using relevant parameters obtained from the deterministic simulator. To evaluate realistic VANET transmissions, we have integrated our hybrid model in fully compliant 802.11 p and 802.11 n physical layers. This framework is then used with the NS-2 network simulator. Our simulation results show that UM-CRT is adapted for VANETs simulations in urban areas as it gives a good approximation of realistic channel propagation mechanisms while improving significantly simulation time. 1

A Semi-Deterministic Channel Model for VANETs Simulations

Today's advanced simulators facilitate thorough studies on Vehicular Ad hoc NETworks (VANETs). However the choice of the physical layer model in such simulators is a crucial issue that impacts the results. A solution to this challenge might be found with a hybrid model. In this paper, we propose a semi-deterministic channel propagation model for VANETs called UM-CRT. It is based on CRT (Communication Ray Tracer) and SCME—UM (Spatial Channel Model Extended—Urban Micro) which are, respectively, a deterministic channel simulator and a statistical channel model. It uses a process which adjusts the statistical model using relevant parameters obtained from the deterministic simulator. To evaluate realistic VANET transmissions, we have integrated our hybrid model in fully compliant 802.11 p and 802.11 n physical layers. This framework is then used with the NS-2 network simulator. Our simulation results show that UM-CRT is adapted for VANETs simulations in urban areas as it gives a good approximation of realistic channel propagation mechanisms while improving significantly simulation time

Latency Reduction Techniques for NB-IoT Networks

Enabling ultra-low latency is one of the major drivers for the development of future cellular networks to support delay sensitive applications including factory automation, autonomous vehicles and tactile internet. Narrowband Internet of Things (NB-IoT) is a 3 rd Generation Partnership Project (3GPP) Release 13 standardized cellular network currently optimized for massive Machine Type Communication (mMTC). To reduce the latency in cellular networks, 3GPP has proposed some latency reduction techniques that include Semi Persistent Scheduling (SPS) and short Transmission Time Interval (sTTI). In this paper, we investigate the potential of adopting both techniques in NB-IoT networks and provide a comprehensive performance evaluation. We firstly analyze these techniques and then implement them in an open-source network simulator (NS3). Simulations are performed with a focus on Cat-NB1 User Equipment (UE) category to evaluate the uplink user-plane latency. Our results show that SPS and sTTI have the potential to greatly reduce the latency in NB-IoT systems. We believe that both techniques can be integrated into NB-IoT systems to position NB-IoT as a preferred technology for low data rate Ultra-Reliable Low-Latency Communication (URLLC) applications before 5G has been fully rolled out

Latency reduction for narrowband URLLC networks: a performance evaluation

Fifth-generation (5G) cellular mobile networks are expected to support mission-critical low latency applications in addition to mobile broadband services, where fourth-generation (4G) cellular networks are unable to support Ultra-Reliable Low Latency Communication (URLLC). However, it might be interesting to understand which latency requirements can be met with both 4G and 5G networks. In this paper, we discuss (1) the components contributing to the latency of cellular networks and (2) evaluate control-plane and user-plane latencies for current-generation narrowband cellular networks and point out the potential improvements to reduce the latency of these networks, (3) present, implement and evaluate latency reduction techniques for latency-critical applications. The two elements we detected, namely the short transmission time interval and the semi-persistent scheduling are very promising as they allow to shorten the delay to processing received information both into the control and data planes. We then analyze the potential of latency reduction techniques for URLLC applications. To this end, we develop these techniques into the long term evolution (LTE) module of ns-3 simulator and then evaluate the performance of the proposed techniques into two different application fields: industrial automation and intelligent transportation systems. Our detailed evaluation results from simulations indicate that LTE can satisfy the low-latency requirements for a large choice of use cases in each field

Impact of realistic simulation on the evaluation of mobile Ad-hoc routing protocols

International audienceToday’s advanced simulators facilitate thorough studies on vehicular ad hocnetworks (VANETs). However, the choice of the physical layer and the mobility models in such simulatorsis a crucial issue that greatly impacts the results. Realistic simulation of routing protocols in VANETs is stillan open question. Indeed, only a few works address routing protocols comparison performed under realisticconditions. This paper compares common reactive, proactive, hybrid, and geographic routing protocolsusing a simulation platform integrating a realistic physical layer and mobility models. It also presents andanalyzes several reactive protocol enhancement propositions dedicated to the VANETs context, such asmultipath routing, but also protocols tuning, which allows it to adapt faster. They all have lot of attentionand are typically proposed to increase the reliability of data transmission. This paper studies the behavior ofeach protocol in different situations and analyzed their advantages and drawbacks. Results presented in thispaper give an important explanation on the contradictory results found in similar works. Finally, our realisticsimulations show that reactive protocols are the best suited for VANETs, and more especially the dynamicMobile Adhoc NETwork on-demand protocol