Resource Allocation in C-V2X: A review

TL;DR

This paper surveys resource allocation for C-V2X by detailing LTE-V2X RA (Mode 3/Mode 4) and NR-V2X RA (Mode 1/Mode 2), including mechanisms such as SPS, DG/CG, and sensing-based selection. It catalogs representative LTE-V2X works (e.g., clustering-based schemes, PEARL/PEARL-RM, MIRD) and NR-V2X approaches (long-term vs short-term sensing, stochastic reservations, DL-based strategies), while also summarizing retransmission schemes and cross-cutting 미래 directions like ML, MEC, and network slicing. The review identifies gaps such as limited attention to Mode 3 and Mode 1, mode-switching, and inter-mode coordination, underscoring the need for innovative RA algorithms to meet URLLC requirements in evolving 5G-V2X networks. By outlining concrete methods and future directions, the paper informs the design of robust, low-latency vehicular communication systems across both LTE and NR paradigms.

Abstract

Cellular Vehicle-to-Everything (C-V2X) is a cutting-edge wireless communication technology that enables seamless connectivity and information exchange among vehicles, infrastructure, networks, and pedestrians. As a vital component of Intelligent Transportation Systems (ITS), C-V2X is designed to support a wide range of applications aimed at enhancing traffic efficiency, improving road safety, reducing accident rates, and facilitating the development of autonomous and connected vehicles. C-V2X technology is built upon the Long-Term Evolution (LTE) and 5G New Radio (NR) standards, leveraging the robustness, reliability, and scalability of cellular networks. It encompasses two distinct communication modes: (1) direct communication, which includes Vehicle-to-Vehicle (V2V), Vehicle-to-Infrastructure (V2I), and Vehicle-to-Pedestrian (V2P) communication, and (2) network-based communication, which involves Vehicle-to-Network (V2N) communication. Resource allocation is a critical challenge in the design and operation of C-V2X systems, as it is responsible for determining the optimal distribution of communication resources among users, ensuring efficient utilization and fair sharing. In C-V2X, resource allocation is complicated by factors such as highly dynamic network topologies, diverse quality of service (QoS) requirements, and spectrum scarcity. Therefore, it is essential to explore and analyze various resource allocation strategies and techniques that can effectively address these challenges. This review paper provides a comprehensive overview of the recent progress in resource allocation for C-V2X communications. As C-V2X technology evolves, it is expected to play a crucial role in transforming the transportation landscape, paving the way for smarter, safer, and more efficient transportation systems.