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An Intelligent V2I-Based Traffic Management System

by Vicente Milanés, Jorge Villagrá, Jorge Godoy, Javier Simó, Joshué Pérez, Enrique Onieva - IEEE Transactions on Intelligent Transportation Systems , 2011
"... Abstract—Vehicles equipped with intelligent systems designed to prevent accidents, such as collision warning systems (CWSs) or lane-keeping assistance (LKA), are now on the market. The next step in reducing road accidents is to coordinate such vehicles in advance not only to avoid collisions but to ..."
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Abstract—Vehicles equipped with intelligent systems designed to prevent accidents, such as collision warning systems (CWSs) or lane-keeping assistance (LKA), are now on the market. The next step in reducing road accidents is to coordinate such vehicles in advance not only to avoid collisions but to improve traffic flow as well. To this end, vehicle-to-infrastructure (V2I) communications are essential to properly manage traffic situations. This paper describes the AUTOPIA approach toward an intelligent traffic management system based on V2I communications. A fuzzy-based control algorithm that takes into account each vehicle’s safe and comfortable distance and speed adjustment for collision avoidance and better traffic flow has been developed. The proposed solution was validated by an IEEE-802.11p-based communications study. The entire system showed good performance in testing in real– world scenarios, first by computer simulation and then with real vehicles. Index Terms—Data communication, road vehicles, traffic con-trol, traffic management, vehicle-to-infrastructure (V2I) commu-nication. I.

VANET Topology Characteristics under Realistic Mobility and Channel Models

by Nabeel Akhtar, Oznur Ozkasap, Sinem Coleri Ergen - In Proceedings of the 2013 IEEE Wireless Communications and Networking Conference (WCNC , 2013
"... Abstract—Developing real-time safety and non-safety applica-tions for vehicular ad hoc networks (VANET) requires under-standing the dynamics of the network topology characteristics since these dynamics determine both the performance of routing protocols and the feasibility of an application over VAN ..."
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Abstract—Developing real-time safety and non-safety applica-tions for vehicular ad hoc networks (VANET) requires under-standing the dynamics of the network topology characteristics since these dynamics determine both the performance of routing protocols and the feasibility of an application over VANET. Using various key metrics of interest including node degree, number of clusters, link duration and link quality, we provide a realistic analysis of the VANET topology characteristics. In this analysis, we integrate real-world road topology and real-time data extracted from Freeway Performance Measurement System database into the microscopic mobility model in order to generate realistic traffic flows along the highway. Moreover, we use more realistic, recently proposed, obstacle-based channel model and compare the performance of this sophisticated model to the most commonly used more simplistic channel models including unit disc and log-normal shadowing model. Our investigation on the key system metrics reveal that largely used unit disc model fails to realistically model communication channel, while parameters of simplistic models like log normal can be adjusted to match the corresponding system metrics of more complex and hard to implement obstacle based model. I.
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Author manuscript, published in "Expert Systems with Applications (2012)"

by J. Pérez A, V. Milanés B, J. Godoy C, J. Villagrá C, E. Onieva D , 2012
"... The AUTOPIA program has been working on the development of intelligent autonomous vehicles for the last ten years. Its latest advances have focused on the development of cooperative manœuvres based on communications involving several vehicles. However, so far, these manœuvres have been tested only o ..."
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The AUTOPIA program has been working on the development of intelligent autonomous vehicles for the last ten years. Its latest advances have focused on the development of cooperative manœuvres based on communications involving several vehicles. However, so far, these manœuvres have been tested only on private tracks that emulate urban environments. The first experiments with autonomous vehicles on real highways, in the framework of the Grand Cooperative Driving Challenge (GCDC) where several vehicles had to cooperate in order to perform Cooperative Adaptive Cruise Control (CACC), are described. In this context, the main challenge was to translate, through fuzzy controllers, human driver experience to these scenarios. This communication describes the experiences deriving from this competition, specifically that concerning the controller and the system implemented in a Citröen C3.
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Platooning With IVC-Enabled Autonomous Vehicles: Strategies to Mitigate Communication Delays, Improve Safety and Traffic Flow

by Pedro Fern, Urbano Nunes, Senior Member
"... Abstract—Intraplatoon information management strategies for dealing with safe and stable operation are proposed in this paper. New algorithms to mitigate communication delays are presented, and Matlab/Simulink-based simulation results are reported. We argue that using anticipatory information from b ..."
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Abstract—Intraplatoon information management strategies for dealing with safe and stable operation are proposed in this paper. New algorithms to mitigate communication delays are presented, and Matlab/Simulink-based simulation results are reported. We argue that using anticipatory information from both the platoon’s leader and the followers significantly impacts platoon string stabil-ity. The obtained simulation results suggest that the effects of com-munication delays may be almost completely canceled out. The platoon presents a very stable behavior, even when subjected to strong acceleration patterns. When the communication channel is subjected to a strong load, proper algorithms may be selected, low-ering network load and maintaining string stability. Upon emer-gency occurrences, the platoon’s timely response may be ensured by dynamically increasing the weight of the platoons ’ leaders data over the behavior of their followers. The simulation results suggest that the algorithms are robust under several demanding scenarios. To assess if current intervehicle communication technology can cope with the proposed information-updating schemes, research into its operation was conducted through a network simulator. Index Terms—Autonomous vehicles, intervehicle communica-tion (IVC), network simulation, platooning, traffic information management, traffic simulation. I.
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Platooning With DSRC-Based IVC-Enabled Autonomous Vehicles: Adding Infrared Communications for IVC Reliability Improvement

by Pedro Fern, Urbano Nunes, Senior Member
"... Abstract — Platooning with IVC-enabled autonomous vehicles may enable a significant increase in lane capacity, if performed with constant spacing policies. However, to be effective, such system is very demanding with respect to communication performance and reliability. Dedicated short range communi ..."
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Abstract — Platooning with IVC-enabled autonomous vehicles may enable a significant increase in lane capacity, if performed with constant spacing policies. However, to be effective, such system is very demanding with respect to communication performance and reliability. Dedicated short range communi-cations (DSRC) is the prominent intervehicle communication (IVC) technology. However, its reliability rises concerns when operating under platooning scenarios. In this paper we identify some specific problems that platooning pose to DSRC, through the simulation of several scenarios implemented in the NS-3 network simulator. Moreover, we propose a new concept of IVC when applied to platoons, using simultaneously two different communication technologies: DSRC and infrared (IR). New gui-delines toward more efficient use of IVC transmission media are suggested, e.g., by broadcasting the event-driven type of mes-sages through DSRC, whereas periodic vehicle control-based messages use the IR channel, in unicast. Furthermore, the base architecture of the IVC proposed system is presented. I.
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1Simulation and Measurement Based Vehicle-to-Vehicle Channel Characterization: Accuracy and Constraint Analysis

by Taimoor Abbas, Senior Member, Thomas Zemen, Senior Member, Senior Member, Fredrik Tufvesson, Senior Member
"... Abstract—In this paper, a deterministic channel model for vehicle-to-vehicle (V2V) communication is compared against channel measurement results collected during a V2V channel measurement campaign using a channel sounder. Channel met-rics such as channel gain, delay and Doppler spreads, eigenvalue d ..."
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Abstract—In this paper, a deterministic channel model for vehicle-to-vehicle (V2V) communication is compared against channel measurement results collected during a V2V channel measurement campaign using a channel sounder. Channel met-rics such as channel gain, delay and Doppler spreads, eigenvalue distribution and antenna correlations are derived from the ray-tracing (RT) simulations as well as from the measurement data obtained from two different measurements in an urban four-way intersection. The channel metrics are compared separately for line-of-sight (LOS) and non-LOS (NLOS) situations. Most power contributions arise from the LOS component (if present) as well as from multipaths with single bounce reflections. Measurement and simulation results of the received power show a very good agreement in the presence of LOS, as most of the received power is carried by the LOS component. In NLOS, the difference is large because the ray-tracer is unable to capture some of the channel characteristics due to the underlying limitations of our ray-based propagation model. Despite the limitations, the model is suitable to characterize some, but not all, of the channel properties in a sufficient manner. We find that the diffuse scattering and multi-bounced non-specular reflections must be considered for an accurate prediction of the channel in such a rich scattering environment. I.

1Vehicle Mobility and Communication Channel Models for Realistic and Efficient Highway VANET Simulation

by Nabeel Akhtar, Sinem Coleri Ergen, Oznur Ozkasap
"... Abstract—Developing real-time safety and non-safety applications for vehicular ad hoc networks (VANETs) requires understanding the dynamics of the network topology characteristics since these dynamics determine both the performance of routing protocols and the feasibility of an application over VANE ..."
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Abstract—Developing real-time safety and non-safety applications for vehicular ad hoc networks (VANETs) requires understanding the dynamics of the network topology characteristics since these dynamics determine both the performance of routing protocols and the feasibility of an application over VANET. Using various key metrics of interest including node degree, neighbor distribution, number of clusters and link duration, we provide a realistic analysis of the VANET topology characteristics over time and space for highway scenario. In this analysis, we integrate real-world road topology and real-time data extracted from the Freeway Performance Measurement System (PeMS) database into a microscopic mobility model to generate realistic traffic flows along the highway. Moreover, we use a more realistic, recently proposed, obstacle based channel model and compare the performance of this sophisticated model to the most commonly used and more simplistic channel models including unit disc and log-normal shadowing models. Our investigation on the key metrics reveals that both log-normal and unit disc models fail to provide realistic VANET topology characteristics. We therefore propose a matching mechanism to tune the parameters of the log-normal model according to the vehicle density and a correlation model to take into account the evolution of the link characteristics over time. The proposed method has been demonstrated to provide a good match with the computationally expensive and difficult to implement obstacle based model. The parameters of the proposed model have been validated to depend only on the vehicle traffic density based on the real data of four different highways in California. Index Terms—vehicular ad hoc networks, simulation, channel model, mobility model I.
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Vehicle Mobility, Communication Channel Modeling and Traffic Density Estimation in VANETs

by Nabeel Akhtar, Nabeel Akhtar, Prof Ceyda Oguz, Prof Attila Gursoy, Assoc Prof, Serdar Tasiran , 2013
"... This is to certify that I have examined this copy of a master's thesis by ..."
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This is to certify that I have examined this copy of a master's thesis by
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Cooperative controllers for highways based on human experience

by J. Péreza, V. Milanésb, J. Godoyc, J. Villagrác, E. Onievad
"... The AUTOPIA program has been working on the development of intelligent autonomous vehicles for the last ten years. Its latest advances have focused on the development of cooperative manœuvres based on communications involving several vehicles. However, so far, these manœuvres have been tested only o ..."
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The AUTOPIA program has been working on the development of intelligent autonomous vehicles for the last ten years. Its latest advances have focused on the development of cooperative manœuvres based on communications involving several vehicles. However, so far, these manœuvres have been tested only on private tracks that emulate urban environments. The first experiments with autonomous vehicles on real highways, in the framework of the Grand Cooperative Driving Challenge (GCDC) where several vehicles had to cooperate in order to perform Cooperative Adaptive Cruise Control (CACC), are described. In this context, the main challenge was to translate, through fuzzy controllers, human driver experience to these scenarios. This communication describes the experiences deriving from this competition, specifically that concerning the controller and the system implemented in a Citröen C3.
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This article has been accepted for inclusion in a future issue of this journal. Content is final as presented, with the exception of pagination. IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS, ACCEPTED FOR PUBLICATION 1 Probabilistic QoS Constrained Robust

by Xin He, Yik-chung Wu
"... Abstract—We study the robust transceiver optimization in downlink multiuser multiple-input multiple-output (MU-MIMO) systems aiming at minimizing transmit power under probabilistic quality-of-service (QoS) requirements. Owing to the unknown distributed interference, the channel estimation error obta ..."
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Abstract—We study the robust transceiver optimization in downlink multiuser multiple-input multiple-output (MU-MIMO) systems aiming at minimizing transmit power under probabilistic quality-of-service (QoS) requirements. Owing to the unknown distributed interference, the channel estimation error obtained from the linear minimum mean square error (LMMSE) estimator can be arbitrarily distributed. Under this situation, the QoS requirements should account for the worst-case channel estimation error distribution. While directly finding the worstcase distribution is challenging, two methods are proposed to solve the robust transceiver design problem. One is based on the Markov’s inequality, while the other is based on a novel duality method. Two convergence-guaranteed iterative algorithms are proposed to solve the transceiver design problems. Furthermore, for the special case of MU multiple-input single-output (MISO) systems, the corresponding robust transceiver design problems are shown to be convex. Simulation results show that, compared to the non-robust method, the QoS requirement is satisfied by both proposed algorithms. Among the two proposed methods, the duality method shows a superior performance in transmit power, while the Markov method demonstrates a lower computational complexity. Furthermore, the proposed duality method results in less conservative QoS performance than the Gaussian approximated probabilistic robust method and bounded robust method. Index Terms—LMMSE channel estimation, QoS, robust MU-MIMO transceiver design, arbitrarily distributed uncertainty. I.
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