Delay Distribution Analysis for Multi-Hop Relay Transmission in a Platoon with C-V2X Sidelink Communication

In vehicle-to-everything (V2X) communication over cellular networks (C-V2X), side link communication, in which vehicles communicate directly without a base station, is newly standardized. As a resource control scheme in C-V2X, sensing-based semi-persistent scheduling(SB-SPS) is adopted. In C-V2X, platooning is one of the promising applications for improving traffic efficiency and road safety. To ensure the stable operation of the platooning, the vehicles need to share road safety-related messages through the relay transmission within the acceptable delay. For such delay-sensitive communication in C-V2X, the delay distribution characteristics based on a mathematical model become helpful information for the system design. This paper proposes delay distribution analysis for multi-hop relay transmission in a platoon with C-V2X sidelink communication. The proposed analytical model provides two contributions: (1) Our mathematical model shows that the probability density function(PDF) of single-hop transmission delay in SB-SPS can expressed as a simple uniform distribution related to just one parameter defined in SB-SPS. (2) The delay distribution of multi-hop relay transmission in a platoon can be obtained by calculating the convolutional integral of the delay PDFs of the vehicles according to the order of packet relaying in a platoon. The validity of the proposed analysis is confirmed through the comparison with simulation results.