Impact of HARQ Retransmissions on Information Age in 5G NR Sidelink

Vehicle to vehicle communication is a part of essential use cases to further improve the vehicular traffic safety and efficiency. The 3rd Generation Partnership Project (3GPP) Rel-16 5G New Radio (NR) sidelink (SL) supports up to 31 blind Hybrid Automatic Repeat reQuest (HARQ) retransmissions for the SL broadcast communication with one of the goals to improve the communication reliability. We simulate a 6 lane highway scenario for low, medium and high traffic density to evaluate the effects of number of HARQ retransmissions on information age (IA). The results indicate a non-linear relationship between number of HARQ retransmissions and the improvement of IA, thus contributing to next stage of selection of appropriate number of HARQ retransmissions. We also analyse the complexities in the existing framework due to various network and system configurations according to Rel-16 standards.