  Applications enabled by Cooperative Intelligent Transport Systems (C-ITS)
represent a major step towards making the road transport system safer and more
efficient (green), and thus suited for a sustainable future. Wireless
communication between vehicles and road infrastructure is an enabler for
high-performance C-ITS applications. State-of-the-art communication systems for
supporting low-latency C-ITS applications are based on IEEE 802.11 medium
access control (MAC) and physical (PHY) layers. In this paper, we argue that a
well-designed 5G system can complement or even replace these systems. We will
review the C-ITS application requirements and explain how these are well
aligned with the foreseen generic 5G service of ultra-reliable machine-type
communication (uMTC). Key technology components suitable for constructing the
uMTC service are identified: reliable service composition (RSC) and
device-to-device (D2D) links for all-to-all broadcast communication,
operational at high mobility and with varying degree of network assistance.
Important problems for future studies, including radio-resource management,
medium access control, and physical layer challenges, are discussed.
