Infrastructure-based Vehicular Networks Research Articles

Q-Learning Relay Placement for Alert Message Dissemination in Vehicular Networks

Alert message (AM) dissemination is a fundamental yet challenging issue in vehicular networks, as it relies on wireless transmissions in a highly mobile, potentially dense, and changing environment. Emerging network infrastructure-based vehicular networks are being considered as an alternative to Vehicular Ad-hoc NETworks (VANETs) for alert message dissemination. Indeed, assuming that Vehicle to Infrastructure (V2I) communication links are nominally available, with some transient and time-limited connectivity losses, recent alert message dissemination schemes primarily rely on V2I links to widely broadcast AMs. Vehicle to Vehicle (V2V) rebroadcasts performed by some selected relay vehicles located within pre-computed rebroadcast zones are then used to ensure the full dissemination within an area of interest. This paper focuses on rebroadcast zones placement. It proposes a Q-learning-based method that computes the minimum number and optimal locations of rebroadcast zones. From these computed zones, the combination of V2I broadcasts with V2V rebroadcasts allows the delivery of AMs in a whole area, even in the presence of locations with poor wireless connectivity. The performance results show that high information coverage and low delivery delays are achieved with our proposed Q-learning based placement. Useless duplicate rebroadcasts and collisions are also avoided, saving network resources.

A Survey on Infrastructure-Based Vehicular Networks

The infrastructure of vehicular networks plays a major role in realizing the full potential of vehicular communications. More and more vehicles are connected to the Internet and to each other, driving new technological transformations in a multidisciplinary way. Researchers in automotive/telecom industries and academia are joining their effort to provide their visions and solutions to increasingly complex transportation systems, also envisioning a myriad of applications to improve the driving experience and the mobility. These trends pose significant challenges to the communication systems: low latency, higher throughput, and increased reliability have to be granted by the wireless access technologies and by a suitable (possibly dedicated) infrastructure. This paper presents an in-depth survey of more than ten years of research on infrastructures, wireless access technologies and techniques, and deployment that make vehicular connectivity available. In addition, we identify the limitations of present technologies and infrastructures and the challenges associated with such infrastructure-based vehicular communications, also highlighting potential solutions.

Fail silence mechanism for dependable vehicular communications

This paper presents a fault-tolerant architecture to improve the dependability of infrastructure-based vehicular networks. For that purpose, a fail silence enforcement mechanism for road-side units (RSUs) was designed, implemented and tested. Vehicular communications based on IEEE 802.11p are inherently non-deterministic. The presence of RSUs and a backhauling network, adds a degree of determinism that is useful to enforce real-time and dependability, both by providing global knowledge and by supporting the operation of collision-free deterministic MAC protocols. One of such protocols is V-FTT, for which the proposed mechanism was designed as a case study. Notice, however that this mechanism is protocol independent and can be adapted to any wireless communications system. The proposed technique is capable of validating a frame for transmission by identifying faults both in value and time domains. Experimental results show that the fail silence enforcement mechanism has low latency and consumes few FPGA resources.

Throughput‐based rate adaptation algorithm for IEEE 802.11 vehicle networks

A key problem with IEEE 802.11 technology is adaptation of the transmission rates to the changing channel conditions, which is more challenging in vehicular networks. Although rate adaptation problem has been extensively studied for static residential and enterprise network scenarios, there is little work dedicated to the IEEE 802.11 rate adaptation in vehicular networks. Here, the authors are motivated to study the IEEE 802.11 rate adaptation problem in infrastructure-based vehicular networks. First of all, the performances of several existing rate adaptation algorithms under vehicle network scenarios, which have been widely used for static network scenarios, are evaluated. Then, a new rate adaptation algorithm is proposed to improve the network performance. In the new rate adaptation algorithm, the technique of sampling candidate transmission modes is used, and the effective throughput associated with a transmission mode is the metric used to choose among the possible transmission modes. The proposed algorithm is compared to several existing rate adaptation algorithms by simulations, which shows significant performance improvement under various system and channel configurations. An ideal signal-to-noise ratio (SNR)-based rate adaptation algorithm in which accurate channel SNR is assumed to be always available is also implemented for benchmark performance comparison.

Mitigating Flooding Attacks on Mobility in Infrastructure-Based Vehicular Networks

Infrastructure-based Vehicular Networks can be applied in different social contexts, such as health care, transportation and entertainment. They can easily take advantage of the benefices provided by wireless mesh networks (WMNs) to mobility, since WMNs essentially support technological convergence and resilience, required for the effective operation of services and applications. However, infrastructure-based vehicular networks are prone to attacks such as ARP packets flooding that compromise mobility management and users' network access. Hence, this work proposes MIRF, a secure mobility scheme based on reputation and filtering to mitigate flooding attacks on mobility management. The efficiency of the MIRF scheme has been evaluated by simulations considering urban scenarios with and without attacks. Analyses show that it significantly improves the packet delivery ratio in scenarios with attacks, mitigating their intentional negative effects, as the reduction of malicious ARP requests. Furthermore, improvements have been observed in the number of handoffs on scenarios under attacks, being faster than scenarios without the scheme.

Multi-Hop Connectivity Probability in Infrastructure-Based Vehicular Networks

Infrastructure-based vehicular networks (consisting of a group of Base Stations (BSs) along the road) will be widely deployed to support Wireless Access in Vehicular Environment (WAVE) and a series of safety and non-safety related applications and services for vehicles on the road. As an important measure of user satisfaction level, uplink connectivity probability is defined as the probability that messages from vehicles can be received by the infrastructure (i.e., BSs) through multi-hop paths. While on the system side, downlink connectivity probability is defined as the probability that messages can be broadcasted from BSs to all vehicles through multi-hop paths, which indicates service coverage performance of a vehicular network. This paper proposes an analytical model to predict both uplink and downlink connectivity probabilities. Our analytical results, validated by simulations and experiments, reveal the trade-off between these two key performance metrics and the important system parameters, such as BS and vehicle densities, radio coverage (or transmission power), and maximum number of hops. This insightful knowledge enables vehicular network engineers and operators to effectively achieve high user satisfaction and good service coverage, with necessary deployment of BSs along the road according to traffic density, user requirements and service types.

Smart Access Points on the road for online gaming in vehicular networks

Online games represent one of the most important revenue sources for entertainment based companies and a challenging field in multimedia application research. With vehicular networks poised to become the new wireless frontier of the Internet, car passengers embody the next consumers that will be targeted by online game providers. Yet, the high mobility and heterogeneity of vehicular networks pose serious challenges; previous work on online games demonstrated the importance of the network’s performance in determining the quality level perceived by consumers. A main problem is related to competing heterogeneous network traffic generated by real-time multimedia applications and concurrent bulk data traffic sharing the same access points along the road. Such problem causes low responsiveness in the gaming application and is further exacerbated by the continuous variations in the number and type of flows, due to the cars’ mobility. To this aim, we show how smart access points can be deployed in infrastructure-based vehicular networks to ensure efficient coexistence among heterogeneous types of flow even in presence of frequent network traffic variations due to the vehicles’ high mobility. As a result, delivery delays are kept small, satisfying the main requirement for the deployment of responsive online games.