A Feasibility Study of LTE-V2X Semi-Persistent Scheduling for String Stable CACC

Abstract

A study on feasibility regarding enabling cooperative adaptive cruise control (CACC) through LTE-V2X Semi-Persistent Scheduling (SPS) is considered. A linear time invariant (LTI) CACC model, previously presented in [1] is revisited. The effect of communication delay on the platoon stability, i.e. string stability, in relation to the CACC parameters is then explained. We study the effects on the SPS period limitations imposed by the LTE-V2X standard by modelling it as a communication delay. The performance of CACC under such considerations is presented and further improved by considering multiple SPS parallel sessions. We show that by following simple conditions on the configuration of multiple SPS parallel sessions, the CACC performance can be further improved. Moreover, by considering multiple SPS parallel sessions following these conditions, the SPS period set is refined in granularity. A refined granularity in the SPS period leads to less redundant transmissions from a stability perspective, which effectively translates to a higher efficiency in radio resource usage when compared to single session SPS.