Automated vehicles rely on onboard sensors to perceive their surroundings and navigate autonomously. However, sensor performance may degrade under adverse weather conditions or when line-of-sight is obstructed. Cooperative perception (or collective perception) is expected to mitigate these limitations by enabling Connected and Automated Vehicles (CAVs) to share sensor data and collaboratively enhance situational awareness. Several studies have analyzed the potential of cooperative perception, yet the fusion of V2X data with information from onboard sensors has received limited focus. V2X data may contain errors that affect the quality of the fused data, and hence the effectiveness of cooperative perception. This study analyzes the impact of sensing measurement errors, V2X packet losses, and GNSS inaccuracies on the effectiveness of cooperative perception. The results highlight the potential of cooperative perception to enhance perception levels and range compared to using onboard sensors alone. However, they also identify key challenges related to the generation of ghost vehicles during the fusion process, which must be addressed to prevent V2X data from introducing additional errors when fused with onboard sensor data.

This paper examines the critical role of intent-sharing in enabling effective maneuver coordination for connected and automated vehicles (CAVs). Successful maneuver coordinations require vehicles to accurately know other vehicles' driving intentions. Intent-sharing can be achieved by the remote vehicles directly communicating their plans with the ego vehicle, as opposed to the ego vehicle predicting the trajectory on the remote vehicles’ behalf. In this paper, we investigate the potential of intent-sharing on maneuver coordination effectiveness by quantifying the percentage of successful coordinations. We analyze the potential of intent-sharing by comparing its effectiveness for coordinated lane changes in a highway scenario with the effectiveness of a trajectory prediction method based on current kinematic data. Our analysis demonstrates in two scenarios substantial improvements in maneuver coordination when CAVs have direct access to the nearby vehicles’ driving intentions through intent sharing. These findings highlight the importance of including intent-sharing in the maneuver coordination protocol.

Connected and automated driving introduces a myriad of new V2X services, such as cooperative perception and maneuver coordination, that significantly increase the channel load and require multi-channel V2X operation. Policies for Multi-Channel Operation (MCO) and congestion control are therefore essential for simultaneously supporting multiple V2X services across several channels. In this context, this paper presents the design, implementation, and extensive validation of a Facilities layer V2X congestion control solution for multi-channel operation integrated into an ETSI-compliant Cooperative Intelligent Transportation Systems (C-ITS) protocol stack. Our approach dynamically adapts transmission parameters based on real-time channel conditions and the priorities and requirements of the V2X services operating in a C-ITS station. By employing a Traffic-Class based proportional fairness strategy, the solution allocates available communication resources among multiple V2X services, effectively responding to varying channel loads in real time. Scalable experimental results in a virtualized environment demonstrate that our solution meets ETSI Release 2 requirements while bridging the gap between simulation-based evaluations and real-world testing, accounting for hardware limitations and processing delays. This work lays a robust foundation for scalable and congestion-aware C-ITS testing and validation prior to real world deployments. This paper makes our code publicly available so that other researchers can replicate our study and further explore MCO solutions for V2X communications.

Teleoperated driving (ToD) enables the remote driving or control of vehicles. For this purpose, vehicles must transmit video feeds to the ToD control center so that the remote operator is fully aware of the driving conditions and can safely control the vehicle. 5G (and beyond) networks are fundamental for the deployment of ToD as they can provide the low latency, reliable and broadband connection necessary to connect the vehicle and ToD control center. However, it is unclear whether common 5G network architectures and configurations are well-suited to support the simultaneous teleoperation of multiple vehicles with demanding uplink bandwidth, as current networks are mainly configured to support mobile broadband services. This paper demonstrates that MEC or edge-based 5G networks are better suited to support and scale the ToD service than centralized networks, and quantifies the bandwidth required to simultaneously teleoperate multiple vehicles under various 5G network architectures and configurations, including different duplexing modes and TDD frame structures. Finally, the study shows that the configuration of the control channels can help mitigate the impact that the processing time of the video feeds has on the capacity to support and scale the ToD service.

Connected and automated vehicles can leverage V2X communications to coordinate their maneuvers. Maneuver coordination is expected to improve traffic efficiency and safety, but the design of maneuver coordination is a challenging task in complex traffic scenarios, as maneuvers affect not only the involved vehicles but also nearby traffic. This study introduces a reference state machine for the design of maneuver coordination. Furthermore, we identify and analyze the challenges that maneuver coordination may encounter. We quantify the relevance of each challenge and propose a set of countermeasures to enhance the robustness and effectiveness of maneuver coordination.

Connected Automated Vehicles (CAVs) will use multiple V2X services to support connected and automated driving functions. The bandwidth required to support such services will augment as CAVs are gradually deployed. It is therefore important to accurately estimate the spectrum requirements to anticipate possible scalability challenges ahead. Current estimations consider a simplified modeling of the transmitter as well as context factors such as the number of vehicles in the communication range. Moreover, they do not accurately model if the Quality of Service (QoS) of the considered V2X services is satisfied or not. This study progresses the state of the art with a novel analytical model that quantifies the bandwidth required to support multiple V2X services. The model considers the impact of the vehicular context, the transmission parameters and the communication requirements to take into account the QoS at the receiver. This is important since adapting the transmission parameters can reduce the channel load but also impacts the probability to correctly receive each packet and therefore the bandwidth required to guarantee a target QoS at the receiver. The proposed model can be adapted to different wireless technologies and messages, but is applied in this study to quantify the bandwidth required by LTE-V2X to support the transmission of CAMs, CPMs and MCMs. The study demonstrates the scalability challenges ahead to support multiple V2X services.

Teleoperated driving (ToD) can support autonomous driving under complex or unexpected traffic scenarios that an autonomous vehicle may not understand or be able to handle. In ToD, autonomous vehicles transmit video feeds and perception data to the remote control center. The operator uses this data to understand the driving environment and remotely control the vehicle that can take over the control once the scenario is resolved. ToD requires reliable and low latency communications between the vehicle and the ToD control center. This study analyzes the feasibility to support ToD with 5G networks. The study demonstrates that the feasibility strongly depends on the bandwidth and the Time Division Duplexing (TDD) frame structure that conditions how the bandwidth is distributed between uplink and downlink transmissions. The study also shows that scaling the number of 5G-supported ToD vehicles requires the vehicles to reduce the video bitrates. The study also shows that traditional centralized 5G network deployments may be challenged by some of the most stringent ToD latency requirements due to the latency introduced by the Internet connection to the ToD control center.

Cooperative perception (a.k.a. Collective perception or cooperative sensing) will allow Connected and Automated Vehicles (CAVs) to share information about detected objects. Cooperative perception improves the sensing accuracy, confidence and range of CAVs, and extends their perception of the driving environment. First message generation rules based on the mobility and dynamics of detected objects have been proposed to decide when a cooperative perception message should be generated and what information it should include. Studies have shown that this type of generation rules can compromise the scalability of cooperative perception and vehicular networks, as they tend to transmit significant amounts of redundant information and generate small and frequent cooperative perception messages that increase the communications overhead. To combat these inefficiencies, this paper proposes and evaluates three techniques that combine, for the first time, baseline mobility-based generation rules for cooperative perception messages with mechanisms to control the redundancy and organize the information about detected objects in order to avoid the frequent transmission of small messages. This study demonstrates that the proposed techniques improve the perception of CAVs and reduce the information age. In addition, the techniques reduce the channel load and improve the scalability of cooperative perception services and vehicular networks. The study demonstrates that the most effective technique is based on: (1) first applying the generation rules to decide whether a cooperative perception message should be generated, (2) then applying redundancy control, and finally (3) organizing the information about all detected objects to avoid small and frequent messages.

Industry 4.0 and 5.0 applications will contribute towards safer, zero-defect and customized production environments. Such applications (e.g. digital twins, collaborative robotics and extended reality) require communication networks capable to satisfy stringent latency, bandwidth, and reliability requirements. Such requirements can be sustained with 5G networks and their evolution that offer unprecedented communications performance and flexibility thanks to the softwarization of networks and the use of network slicing. Network slicing creates different logical partitions or slices of the common network infrastructure and configures each slice to the requirements of the applications it will support. RAN (Radio Access Network) slicing is a fundamental part of network slicing in 5G as the radio channel is prone to errors and this impacts the capacity to support stringent reliability requirements. To date, RAN slices have been created considering the number of radio resources that must be reserved to guarantee the transmission rate or bandwidth demanded by the applications they will serve. This study demonstrates that this design approach cannot guarantee satisfying the reliability requirements of industrial applications and proposes a novel RAN slice descriptor that takes into account both the reliability and transmission rate requirements of the applications.

Cellular networks usually support non-safety-critical V2X services using Vehicle-to-Network (V2N) connections. However, the flexibility and capabilities of 5G have triggered interest in analyzing whether 5G could also support advanced V2X services using Vehicle-to-Network-to-Vehicle (V2N2V) connections instead of direct Vehicle-to-Vehicle (V2V) connections. V2N2V requires the integration of the 5G network with computing platforms for processing the V2X packets. The flexibility introduced by 5G facilitates the integration with multiple computing platforms such as Multi-access Edge Computing (MEC), edge cloud, shared data center or central cloud. This results in alternative 5G network deployments with the computing platform installed at different locations between the base station and the Internet. These deployments can have important technical implications for supporting V2X services. In this study, we analyze the impact of different 5G and computing platform deployments on the end-to-end (E2E) latency of V2N2V communications under multi-MNO (Mobile Network Operator) scenarios since vehicles may be served by different operators. We also identify which deployment strategies are more suitable to meet the latency requirements of V2X services for connected and automated driving.

5G and multi-access edge computing (MEC) are being considered to support V2X services demanding low latency and highly reliable communications using V2N2V (Vehicle-to-Network-to-Vehicles) communications instead of direct or sidelink V2V (Vehicle-to-Vehicle). Guaranteeing V2X service continuity using V2N2V is a challenging task in multi-Mobile Network Operator (MNO) deployments where vehicles are supported by different MNOs. MEC federations have been proposed to address some of these challenges. A MEC federation is a federated model of MEC systems enabling shared usage of MEC services and applications. Through MEC federations, vehicles can seamlessly access V2X applications independently of whether they are hosted on their MNO’s MEC, or on the MEC of a different (but federated) MNO. This paper presents the first study that analyses the impact of MEC federation on the end-to-end (E2E) latency when supporting V2X services using 5G V2N2V in multi-MNO scenarios. The paper also evaluates the feasibility to support the latency requirements of advanced V2X services in these scenarios, and the benefits introduced by MEC federation. This study considers the V2Xbased cooperative lane merge service as a case study.

Connected Automated Vehicles (CAVs) can utilize V2X communications to exchange their driving intentions and coordinate maneuvers. Previous studies have shown that maneuver coordination can improve traffic efficiency and safety. However, these studies focus on specific scenarios with a limited number of vehicles. Large-scale evaluations with complex interactions among vehicles are necessary to fully recognize the impact of maneuver coordination and to understand how to effectively design and conFigure maneuver coordination. This study progresses the state-of-the-art with a large-scale evaluation of lane change maneuver coordination in a highway scenario. We show how maneuver coordination impacts the traffic distribution and improves traffic fairness. Our study also highlights the need to consider safety when designing maneuver coordination and demonstrates that the coordination triggering conditions impact the execution of the coordination and their spatiotemporal distribution.

Connected and automated vehicles (CAVs) are expected to make use of Vehicle-to-Everything (V2X) communication to exchange sensor and trajectory data. Using this data, CAVs can coordinate their maneuvers for safer and more efficient driving. ETSI and SAE are currently working to define standards for maneuver coordination and cooperative driving. The current approach at ETSI is based on a distributed solution where vehicles use Vehicle-to-Vehicle (V2V) communication to exchange their planned and desired trajectories. This study evaluates the potential benefits of the ETSI Maneuver Coordination Service to improve the traffic speed using a unique simulation tool. To do so, we first evaluate the impact of maneuver coordination on the vehicles involved in a coordination process. We also evaluate the effects of maneuver coordination on the overall traffic compared to scenarios without coordination. Our study shows that maneuver coordination can yield significant benefits to traffic mobility, however these improvements are intimately linked to the surrounding traffic environment and the specifications of the coordinated maneuver. This highlights the need for more detailed studies on the design of maneuver coordination protocols that should consider the vehicular context when executing and configuring the coordination process.

5G offers high flexibility at the radio, transport and core networks to support various services of critical verticals such as connected and automated driving. At the Radio Access Network (RAN), 5G defines a New Radio (NR). 5G NR utilizes different subcarrier spacing, slot durations, modulations and channel coding schemes. This flexibility offers the possibility to support automotive services with different and demanding requirements, such as Advanced Driver-Assistance System (ADAS), cooperative driving, and remote driving. Previous studies showed that 5G NR can be configured to achieve latencies below 2 ms. However, existing studies are generally restricted to scenarios with a limited number of users and unlimited bandwidth. Therefore, it is important to analyze whether 5G NR can effectively support these services as the network scales under limited spectrum allocations. This study advances the current state of the art to demonstrate that the capability of 5G NR RAN to support advanced V2X services depends on the RAN configuration (subcarrier spacing, slot duration and error protection) and network load.

Connected and automated vehicles will enable advanced traffic safety and efficiency applications thanks to the dynamic exchange of information between vehicles, and between vehicles and infrastructure nodes. Connected vehicles can utilize IEEE 802.11p for vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2I) communications. However, a widespread deployment of connected vehicles and the introduction of connected automated driving applications will notably increase the bandwidth and scalability requirements of vehicular networks. This paper proposes to address these challenges through the adoption of heterogeneous V2V communications in multi-link and multi-RAT vehicular networks. In particular, the paper proposes the first distributed (and decentralized) context-aware heterogeneous V2V communications algorithm that is technology and application agnostic, and that allows each vehicle to autonomously and dynamically select its communications technology taking into account its application requirements and the communication context conditions. This study demonstrates the potential of heterogeneous V2V communications, and the capability of the proposed algorithm to satisfy the vehicles' application requirements while approaching the estimated upper bound network capacity.

Wireless congestion control and resource allocation for 802.11p based V2X safety communication have been widely investigated for a single Cooperative Awareness service, considering homogeneous resource requirement per vehicle. Future cooperative connected vehicles, will have heterogeneous capabilities and communication needs, which existing congestion control mechanisms have not fully addressed. In this paper, we analyze issues with the channel congestion control protocol standardized in Europe by ETSI, regarding distributed resource allocation for heterogeneous number of services and message types per vehicle. We present a cooperative congestion control mechanism to orchestrate channel resource among a mixed distribution of vehicles with diverse resource requirements under channel congestion. Simulation based evaluation using standardized safety messages show the application performance improvement rendered by our proposed mechanism, compared to the standardized protocol.

Vehicular networks are based on the wireless exchange of information between vehicles and between vehicles and road side units. To avoid overloading the radio channel, different distributed congestion control mechanisms have been proposed in the literature. A widely adopted mechanism to control congestion is packet rate control. It controls the number of packets that each vehicle transmits to the radio channel through packet dropping. Packet dropping has been shown to effectively improve the radio communications performance thanks to the reduction of the channel load and packet collisions. However, from the application perspective, packets dropped by congestion control mechanisms are not transmitted and are therefore lost. This paper demonstrates for the first time that, while packet dropping can improve the performance at the radio level, it degrades the performance at the application level. This raises the question on whether current congestion control protocols based on packet dropping are actually suitable for vehicular networks.

Cooperative perception (or cooperative sensing or collective perception) enables connected and automated vehicles to exchange sensor data in order to improve their perception of the driving environment. ETSI is currently developing a standard for collective perception. The standard defines the message format and generation rules. These rules identify when a message should be transmitted and what information it should include. This study shows first that the current ETSI solution generates many redundant collective perception messages that increase the channel load and can compromise the networks' scalability. Unnecessary redundancy can reduce the reliability of V2X (Vehicle to Everything) communications and ultimately decrease the effectiveness of collective perception. This study proposes a modification of the current ETSI solution to control redundancy and avoid the transmission of unnecessary CPM data or messages. The evaluation shows that our proposal significantly reduces the redundancy and channel load and improves the reliability of V2X communications compared to current ETSI solution for collective perception. This is achieved while maintaining the perception achieved by ETSI for the safety-critical short and medium distances.

Connected and automated vehicles can exploit V2X communications to coordinate their maneuvers and improve the traffic safety and efficiency. To support such coordination, ETSI is currently defining the Maneuver Coordination Service (MCS). The current approach is based on a distributed solution where vehicles coordinate their maneuvers using V2V (Vehicle-to-Vehicle) communications. This paper proposes to extend this concept by adding the possibility for the infrastructure to support cooperative maneuvers using V2I (Vehicle-to-Infrastructure) communications. To this aim, we propose a Maneuver Coordination Message (MCM) that can be used in cooperative maneuvers with or without road infrastructure support. First results show the gains that cooperative maneuvers can achieve thanks to the infrastructure support. This paper also analyses and discusses the need to define MCM generation rules that decide when MCM messages should be exchanged. These rules have an impact on the effectiveness of cooperative maneuvers and on the operation and scalability of the V2X network.

Collective Perception (CP) or cooperative sensing enables vehicles and infrastructure nodes to exchange sensor information to improve their perception of the driving environment. CP enables vehicles to detect objects (e.g. non-connected vehicles, pedestrians, obstacles, etc.) beyond their local sensing capabilities. ETSI is currently developing the European standards for collective perception or cooperative sensing. This includes defining which information should be exchanged about the detected objects, and how often it should be exchanged. To this aim, different CP generation rules for collective perception are currently under analysis, and this paper presents an in-depth analysis of their performance and efficiency. The conducted analysis highlights the existing tradeoffs between performance (capacity to detect surrounding objects) and efficiency (redundant detection and transmission of the same detected objects). It also demonstrates the need to design advanced policies that dynamically control the redundancy on the wireless channel while ensuring the capacity to reliably detect the driving environment.

The 3GPP has released the C-V2X standard to support V2X (Vehicle-to-Everything) communications using the LTE sidelink PC5 interface. This standard includes two modes of operation, and this study focuses on the Mode 4. This mode does not require the support of the cellular infrastructure, and vehicles can autonomously select their sub-channels for their V2V transmissions. The adequate operation of C-V2X Mode 4 requires a careful configuration of its main parameters. This study analyzes the optimum configuration of the parameters that mostly influence the operation and performance of C-V2X or LTE-V Mode 4. This analysis is conducted for different channel loads and traffic conditions. The conclusions obtained are compared with existing studies taking into account the importance of using accurate models for adequately configuring the C-V2X Mode 4 interface.

V2X deployments using IEEE 802.11p have already been announced, and the 3GPP has published the first Cellular V2X standard based on LTE-V. The limitations of IEEE 802.11p and LTE-V, and the increasing requirements of enhanced V2X applications, raise the question of whether existing V2X standards can provide the reliability levels required to support large scale deployments and the introduction of connected automated driving. Redundancy (two or more V2X links) can increase the reliability, but the gains can be limited if the various links are correlated. IEEE 802.11p and LTE-V utilize sensing-based scheduling schemes, and their MAC errors can hence be correlated since they both suffer packet collisions due to the hidden terminal problem. To address this limitation, this paper proposes the design of multi-link V2X communications where the operation of a link is adjusted with the information received through the other link. This approach is applied in this paper to design an IEEE 802.11p-assisted LTE-V scheduling scheme for multi-link and multi-RAT V2X communications. The proposed scheme is designed to increase the reliability of V2V communications in intersections under NLOS conditions.

The IEEE 802.11p standard has been created for vehicle to vehicle and vehicle to infrastructure communications. Vehicular networks require vehicles to periodically broadcast beacons in order to detect nearby vehicles or road infrastructure nodes and exchange critical information. The IEEE 802.11p standard defines different data rates that can be used for such transmissions, but 6 Mbps has been generally assumed as the default data rate. Limited efforts have been conducted to date to demonstrate whether 6 Mbps is the optimum data rate or not. This study addresses this issue, and demonstrates by means of simulations and field experiments that 6 Mbps is not (always) the optimum data rate for beaconing in vehicular networks. The conclusions are validated in both urban and highway environments.

Wireless communication technologies will represent an essential technological component of the Factories of the Future in order to facilitate the real-time monitoring of the industrial processes, as well as the working conditions and the workers' health and safety. To this aim, wireless sensor networking technologies are being evolved to overcome the industrial challenging propagation environments and guarantee the strict QoS requirements characterizing industrial applications. However, a major future demand for wireless industrial systems could be the capability to support mobility. In this context, this paper analyzes the impact of mobility on the performance of industrial wireless communication systems based on a centralized management like the WirelessHART standard.

Improving the workers' health and safety should be a key priority in the design and development of the Factory of the Future concept. To this aim, ICT and wireless communication technologies in particular, can represent very valuable tools to implement distributed and mobile sensing applications capable to continuously sense the working environment and the workers' health and safety conditions. However, the harsh propagation conditions that can characterise industrial environments can complicate the efficient and reliable deployment of wireless solutions in factories. In this context, this paper evaluates the reliability and connectivity of heterogeneous wireless technologies that can be used for implementing fixed and mobile sensing applications.

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 vehicle's 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.

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 application's 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.

Wireless vehicular communication systems require the design and implementation of robust and efficient communication policies to provide the strict quality of service needed by traffic safety applications while guaranteeing the system's scalability. To efficiently guarantee such requirements, the authors have developed an opportunistic-driven adaptive radio resource management mechanism that adapts the transmission parameters based on the operating conditions and traffic safety requirements. Since the performance of adaptive communication techniques can be importantly influenced by channel correlation, this work proposes several compensation policies that allow the proposed opportunistic mechanism to efficiently meet the traffic safety quality of service requirements even under correlated radio channels.

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 node's 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 protocol's performance, and understand its networking operation.

The adoption of wireless vehicular communication technologies would strongly depend on the technologies transmission reliability, required by QoS demanding traffic safety applications, and the system's scalability as the technology is gradually introduced. To this aim, this work proposes the use of opportunistic transmission policies that dynamically adapt the transmission parameters based on the operating conditions and potential traffic safety risks. The work analyses different configuration proposals with the aim to meeting the strong traffic safety QoS requirements, while maximizing the technology's robustness and minimising channel congestion, which in turn is crucial to guarantee the future system's scalability.

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 an efficient use of the radio channel resources. To this end, this work proposes and analyses an opportunistic-driven adaptive radio resource management scheme that achieves the target traffic safety performance and efficiently uses the transmission and channel resources.

The use of wireless vehicular communication systems for traffic safety applications imposes a careful and adequate communications dimensioning to ensure the transmission of broadcast safety messages in a timely manner. To date, several studies have proposed an adaptive dimensioning of the inter- vehicle communication protocols based on the particular operating conditions of the transmitting vehicles. This work complements these initial investigations by proposing and demonstrating the need to dimension such communication protocols not only based on the operating conditions but also on the vehicular context. By modifying the communication parameters based on the presence of nearby vehicles, the proposed context-based communications dimensioning reduces the risk of chain collisions.