 communications for Intelligent Transport System applications; September 2015. 3GPP specifications can be accessed at the following URL: http://www.3gpp.org/ftp/Specs/archive/ Vehicle-to-Everything (V2X) Communications [13] 5G Americas White Paper. V2X cellular solutions; October 2016. [14] 5G Americas White Paper. Cellular V2X communications towards 5G; March 2018. [15] K. Lee, et al., Latency of cellular-based V2X: Perspectives on TTI-proportional latency and TTI-independent latency, IEEE Access 5 (2017). [16] M. Boban, et al., Use cases, requirements, and design considerations for 5G V2X, IEEE Vehicular Technol Mag, December 2017. [17] R. Molina-Masegosa, J. Gozalvez, LTE-V for sidelink 5G V2X vehicular communications, IEEE Vehicular Technol Mag, December 2017. [18] Rohde & Schwarz White Paper. LTE-advanced (Release 12) technology introduction; September 2014. [19] Rohde & Schwarz White Paper. Device to device communication in LTE; September 2015. [20] Husain S, et al. An overview of standardization efforts for enabling vehicular-to-everything services. IEEE Conference on Standards for Communications and Networking (CSCN); September 2017. S. Chen, et al., Vehicle-to-everything (V2X) services supported by LTE-based systems and 5G, IEEE Commun Standards Mag, June 2017. [22] H. Seo, et al., LTE evolution for vehicle-to-everything services, IEEE Commun Mag, June 2016. [23] Kousaridas A, et al. Recent advances in 3GPP networks for vehicular communications. IEEE Conference on Standards for Communications and Networking (CSCN); September 2017. [24] ETSI TS 102 687 V1.2.1. Intelligent transport systems (ITS); Decentralized congestion control mechan- isms for intelligent transport systems operating in the 5 GHz range; Access Layer Part; April 2018. [25] Khoryaev A. Evolution of cellular-V2X (C-V2X) technology use cases, technical challenges, and radio- layer solutions for connected cars. IEEE ComSoc Webinar; March 2018. 5GAA Automotive Association. An assessment of LTE-V2X (PC5) and 802.11p direct communications techno