Performance Evaluation of DSRC and C-V2X Coexistence in the 5.895-5.925 GHz Spectrum

Two competing radio access technologies (RATs) are presently available for intelligent transportation systems: Dedicated short-range communication (DSRC) and cellular vehicle-to-everything (C-V2X). Recent FCC rulings allocate 30 MHz worth of spectrum (5.895-5.925 GHz) for both RATs, recommending 20 MHz (2 channels) for C-V2X and 10 MHz (one channel) for DSRC. However, significant debate has ensued on the optimality of such a split, not to mention the fact that it does not consider the possibility of both DSRC and C-V2X coexisting over the same channel. In this paper, we study various performance metrics related to the coexistence of DSRC and C-V2X, considering different configuration parameters under both highway and urban scenarios. Extensive simulations are conducted using WiLabV2XSim, a discrete-event simulation tool for modeling vehicular networks. Our results reveal that, contrary to common wisdom, in highway scenarios it is more efficient to assign two channels for DSRC and one channel for C-V2X. Conversely, in urban scenarios, allocating one channel for DSRC and two channels for C-V2X leads to superior performance. The paper also discusses various challenges for coexistence between DSRC and C-V2X, including interference and differences in the MAC layer designs. Overall, the study provides insights into optimizing the allocation of channels between DSRC and C-V2X to mitigate the effects of coexistence and improve the performance of vehicular communication systems.