The connected car concept is gaining momentum from the point of view, not only of research, but also of standardization and industrial development. Today there are many options for connecting a vehicle, in terms of to whom and how. In addition to making use of any conventional cellular technology, and connecting the vehicle to a base station or infrastructure element, vehicles can connect wirelessly and directly to each other using different technologies, both from the Institute of Electrical and Electronics Engineers (IEEE) and from the 3rd Generation Partnership Project (3GPP). This article offers a rigorous and detailed review of the system architecture aspects involved in the support of vehicular communications by the 3GPP fifth-generation (5G) standard, with special emphasis on its most recent iteration: Release 16.

This paper deals with the potential of Third Generation Partnership (3GPP) Project mobile cellular standards to enable vehicular communications. Starting from 3GPP Release 15, and Release 16 specifications for Vehicle-to-Everything (V2X) communications, the different communication modes, interfaces and use cases for V2X based on Long Term Evolution (LTE) and New Radio (NR) are analyzed. This research also studies the potential beneficial impact on V2X of a network that is aware of the underlying Multi-RAT Dual Connectivity (MR-DC) architecture. The methodology followed in this work consists of a review of 3GPP standards for vehicular communications based on mobile networks. The performance evaluation of the communication modes was performed through simulations taking into account resource allocation schemes, packet transmission frequencies, packet size, vehicle density and other parameters defined in the standard. In order to perform simulations of the decentralized communication mode (mode 4), a simulator based on OMNeT++ was configured. For the centralized mode (mode 3), an analytical model in MATLAB was used to configure different simulation scenarios. The results obtained indicate that LTE networks can only support basic V2X use cases because they do not demand strict potential requirements. Simulations showed that the centralized mode offers better performance than mode 4; however, it requires cellular network coverage. More advanced use cases are key for a future Intelligent Transport System (ITS), high-performance networks (i.e., Fifth Generation (5G), NR) are expected to coexist gradually with LTE in the V2X landscape. Therefore, in order to meet the strict requirements for latency, transmission speed and reliability, MR-DC architectures combining different radio access technologies, communication modes and connection interfaces should be deployed. In addition, operation in multi-operator and cross-border scenarios must be guaranteed.

New Radio (NR) Vehicle-to-Everything (V2X) communications, a subject of the Third Generation Partnership Project (3GPP) specifications for 5G networks, enable vehicle communications akin to Long Term Evolution (LTE). These communications can be implemented either centrally, by connecting to 5G nodes, or autonomously, by establishing sidelink through the PC5 interface. Particularly noteworthy is the latter connection mode, referred to as Mode 2, which is independent of cellular network coverage. Instead, communication is established using pre-configured parameters and a sensing mechanism for resource selection and allocation in time and frequency. This paper delineates the resource selection procedures for NR VV2X Mode 2 and evaluates their performance across various scenarios. The findings suggest superior performance of high numerologies compared to smaller subcarrier spacings. Even though the standard prescribes a random method for V2X resource selection, it was observed that the sensing procedures yield higher Packet Reception Ratio (PRR) levels. Moreover, factors such as a smaller sidelink channel size and an extended duration of the candidate resource sensing window were found to enhance the frequency diversification of resources, thereby improving PRR levels. A qualitative examination of key considerations for the performance evaluation of Radio Access Technologies (RAT) V2X communications is also provided, delving into aspects such as RAT interplay, resource utilization, interoperability, performance trade-offs, and Quality of Service (QoS) for optimal management of multi-RAT V2X scenarios.

Context-aware mobile applications operating in environments with intermittent or unreliable connectivity must support offline-first behavior while preserving consistent decision-making and timely synchronization. Traditional cloud-centric architectures often fail to provide adequate availability, responsiveness, and reliable context reasoning under such conditions. This paper presents CAMS-F Edge DTN, an edge-centric runtime designed to support offline-first context-aware applications operating under intermittent connectivity. The proposed approach extends the CAMS domain-specific language (DSL) with declarative policies for semantic reconciliation, opportunistic synchronization, and context-aware conflict resolution. The runtime integrates Conflict-Free Replicated Data Types (CRDTs), opportunistic communication channels such as Bluetooth and Wi-Fi Direct, and MQTT-SN messaging to enable robust data exchange across mobile, vehicular, and edge nodes. CAMS F-Edge DTN supports offline-first execution by allowing applications to evaluate contextual rules locally and reconcile distributed state asynchronously when connectivity becomes available. The approach is evaluated through controlled experiments and case studies in rural logistics and healthcare distribution scenarios. The experimental results show that the proposed architecture maintains 96–99% operational availability under intermittent connectivity and up to 100% availability during fully offline operation, while achieving low-latency local reasoning (<10 ms median latency) and deterministic state convergence through CRDT-based synchronization mechanisms.