  With the rapid development of communications and computing, the concept of
connected vehicles emerges to improve driving safety, traffic efficiency and
infotainment experience. Due to the limited capabilities of sensors and
information processing on a single vehicle, vehicular networks (VNETs) play a
vital role for the realization of connected vehicles. To achieve the closer
cooperation on the road, ultra-reliable and low-latency communications (URLLCs)
become the indispensable components of future VNETs. However, traditional
wireless networks are designed with the objective of maximizing spectral and
energy efficiency regardless of adequate consideration of URLLCs. To this end,
this article investigates the challenges and solutions of conceiving URLLC
VNETs dedicated for connected vehicles. Specifically, the underlying
application scenarios are first presented with various vehicular communication
patterns. Then, the URLLC requirements and potential challenges are discussed
for VNETs. We also discuss the solutions to establish URLLC VNETs from the
aspects of physical and media access control layers, including the optimization
frameworks for latency and reliability, as well as the case studies of
employing such frameworks. Finally, several open research directions are
pointed out.
