Miguel Sepulcre

Congestion and Awareness Control in Cooperative Vehicular Systems

Cooperative vehicular systems have been identified as a promising solution to overcome the current and future needs for increasing traffic safety and efficiency, while providing infotainment and added-value services on the move. To achieve their objectives, cooperative vehicular systems will be based on wireless communications between vehicles and with other infrastructure nodes, and will have to deal with highly dynamic nodes, challenging propagation conditions, and stringent application requirements. By looking at cooperative applications and their data traffic, as well as the current and foreseen spectrum allocations for cooperative vehicular systems, there is a risk that the corresponding radio channels could easily be saturated if no control algorithms are used. The saturation of the radio channels would result in unstable vehicular communications, and thus in an inefficient operation of cooperative systems. As a prime example of upcoming ubiquitous networks contributing to the vision of “a thousand radios per person,” cooperative vehicular systems need to be designed to scale to high densities of radios without centralized coordination, while at the same time guaranteeing the requirements of the implemented applications and services, for example the stringent needs of active traffic safety applications. In this paper, we survey and classify various decentralized methods to control the load on the radio channels and to ensure each vehicles capacity to detect and communicate with the relevant neighboring vehicles, with a particular focus on approaches based on transmit power and rate control. Finally, we discuss the open research challenges that are imposed by different application requirements and potential existing contradictions.

Contextual Communications Congestion Control for Cooperative Vehicular Networks

The wide scale deployment of cooperative vehicular ad-hoc networks will require the design of efficient congestion control policies that guarantee stable and reliable communications between vehicles and with infrastructure nodes. These policies should reduce the load on the communications channel, while satisfying the strict applications reliability requirements. To this aim, this letter proposes and evaluates a contextual cooperative congestion control policy that exploits the traffic context information of each vehicle to reduce the channel load, while satisfying the vehicular applications requirements.

Impact of the radio channel modelling on the performance of VANET communication protocols

The expected traffic safety and efficiency benefits that can be achieved through the development and deployment of vehicular ad-hoc networks has attracted a significant interest from the networking research community that is currently working on novel vehicular communication protocols. The time-critical nature of vehicular applications and their reliability constraints require a careful protocol design and dimensioning. To this aim, adequate and accurate models should be employed in any research study. One of the critical aspects of any wireless communications system is the radio channel propagation. This is particularly the case in vehicular networks due to their low antenna heights, the fast topology changes and the reliability and latency constraints of traffic safety applications. Despite the research efforts to model the vehicle-to-vehicle communications channel, many networking studies are currently simplifying and even neglecting the radio channel effects on the performance and operation of their protocols. As this work demonstrates, it is critical that realistic and accurate channel models are employed to adequately understand, design and optimize novel vehicular communications and networking protocols.

ITETRIS: a modular simulation platform for the large scale evaluation of cooperative ITS applications

Cooperative ITS systems are expected to improve road traffic safety and efficiency, and provide infotainment services on the move, through the dynamic exchange of messages between vehicles, and between vehicles and infrastructure nodes. The complexity of cooperative ITS systems and the interrelation between its components requires their extensive testing before deployment. The lack of simulation platforms capable to test, with high modelling accuracy, cooperative ITS systems and applications in large scale scenarios triggered the implementation of the EU-funded iTETRIS simulation platform. iTETRIS is a unique open source simulation platform characterized by a modular architecture that allows integrating two widely adopted traffic and wireless simulators, while supporting the implementation of cooperative ITS applications in a language-agnostic fashion. This paper presents in detail the iTETRIS simulation platform, and describes its architecture, standard compliant implementation, operation and new functionalities. Finally, the paper demonstrates iTETRIS large scale cooperative ITS evaluation capabilities through the implementation and evaluation of cooperative traffic congestion detection and bus lane management applications. The detailed description and implemented examples provide valuable information on how to use and exploit iTETRIS simulation potential.

Application-Based Congestion Control Policy for the Communication Channel in VANETs

This letter proposes a novel proactive congestion control policy for vehicular ad-hoc networks, in which each vehicles communication parameters are adapted based on their individual application requirements. Contrary to other approaches, where transmission resources tend to be assigned based on system-level performance metrics, the technique proposed in this paper aims to individually satisfy the target application performance of each vehicle, while globally minimising the channel load to prevent channel congestion.

On the importance of application requirements in cooperative vehicular communications

Cooperative vehicular systems are being developed to improve traffic safety and efficiency through the dynamic exchange of information between vehicles and between vehicles and infrastructure units. Different communication protocols and policies have been proposed in the literature with diverse objectives, normally taking into account network performance metrics only. This paper illustrates the need of taking into account cooperative vehicular application requirements in the design and operation of cooperative vehicular protocols, such as congestion control protocols. The results obtained demonstrate the impact of the application requirements on the communication settings of each vehicle, and on the overall channel load generated.

Opportunistic technique for efficient wireless vehicular communications

Vehicle-to-vehicle and vehicle-to infrastructure wireless systems are currently under development to improve the traffic safety and efficiency while providing Internet connectivity on the move. A widespread adoption of these wireless vehicular communication technologies will require efficient use of the radio channel resources. To this end, this work proposes and analyzes an opportunistic-driven adaptive radio resource manage merit (OPRAM) scheme that achieves tin- target traffic safety performance and efficiently uses the transmission and channel resources.

Operation and Performance of Vehicular Ad-Hoc Routing Protocols in Realistic Environments

Vehicle-to-vehicle and vehicle-to-infrastructure wireless communications are currently under development to improve traffic efficiency and safety. Routing protocols enabling multi-hop communications represent a major technology for information dissemination within vehicular ad-hoc networks. The high nodes mobility and propagation conditions experienced by vehicle-to-vehicle communications require a careful routing protocol design to ensure its successful operation and performance under realistic environments. To this aim, this paper analyses the impact and importance of adequately considering physical layer effects to correctly quantify a routing protocols performance, and understand its networking operation.

Making cars a main ICT resource in smart cities

As cars are ubiquitous in todays and tomorrows cities they could play a major role in the communication of the future. In the last years the development of Inter-Vehicle Communication (IVC) took huge steps forward and therefore gives us exactly the tools needed to accomplish this task. We propose an architecture, named Car4ICT, that puts cars into the middle of future ICT systems. In this system users are able to offer and request services; at the same time, members are in charge of discovering the services and routing the data between users. Members are always cars, therefore they are the central part of our architecture. A user can be a human using a smartphone, a machine offering sensor readings, or even a car which offers storage, processing power, or its own sensor readings. We outline the architecture of our system and the different concepts to connect the users and the members. As such services cannot easily be described with known concepts, we outline our way of identifying the services. Additionally, we present some initial proof of concept simulation results that show the immense potential of the system.

Adaptive beaconing for congestion and awareness control in vehicular networks

Cooperative vehicular networks require the exchange of positioning and basic status information between neighboring nodes to support higher layer protocols and applications, including active safety applications. The information exchange is based on the periodic transmission/reception of 1-hop broadcast messages on the so called control channel. The dynamic adaptation of the transmission parameters of such messages will be key for the reliable and efficient operation of the system. On one hand, congestion control protocols need to be applied to control the channel load, typically through the adaptation of the transmission parameters based on certain channel load metrics. On the other hand, awareness control protocols are also required to adequately support cooperative vehicular applications. Such protocols typically adapt the transmission parameters of periodic broadcast messages to ensure each vehicles capacity to detect, and possibly communicate, with the relevant vehicles and infrastructure nodes present in its local neighborhood. To date, congestion and awareness control protocols have been normally designed and evaluated separately, although both will be required for the reliable and efficient operation of the system. To this aim, this paper proposes and evaluates INTERN, a new control protocol that integrates two congestion and awareness control processes. The simulation results obtained demonstrate that INTERN is able to satisfy the applications requirements of all vehicles, while effectively controlling the channel load.