Performance Evaluation of C-V2X Mode 4 Communications

Cellular vehicular-to-everything (C-V2X), as a key technology of Internet of Vehicles (IoVs), is expected to improve road traffic safety and achieve intelligent transportation. C-V2X mainly supports two communication modes, Mode 3 and Mode 4. Mode 3 supports centralized control and management of network resources whereas Mode 4 allows vehicles to select radio resources independently for data transmission without the aid of network infrastructures. In this paper, we present an overview of C-V2X Mode 4 communication and stress several major enhancements compared to long term evolution (LTE), including subframe structure design, synchronization mechanism, resource pool configuration, and resource scheduling mechanism, i.e., sensing-based semi-persistent scheduling (S-SPS), etc. To evaluate the transmission performance of C-V2X, we set up a system-level simulation platform based on the integration of traffic simulator CarMaker and network simulator (NS)-3, where CarMaker is utilized to simulate real vehicle trajectories and NS-3 is applied to implement the communication protocols of C-V2X. Under various simulation scenarios, the transmission performance in terms of packet reception ratio (PRR) is examined and the impacts of resource scheduling parameters, including resource reselection probability, resource reservation interval and channel bandwidth on PRR are evaluated.