  Ultra-reliable and low-latency communication (URLLC) is one category of
service to be provided by next-generation wireless networks. Motivated by
increasing security concerns in such networks, this article focuses on physical
layer security (PLS) in the context of URLLC. The PLS technique mainly uses
transmission designs based on the intrinsic randomness of the wireless medium
to achieve secrecy. As such, PLS is of lower complexity and incurs less latency
than traditional cryptography. In this article, we first introduce appropriate
performance metrics for evaluating PLS in URLLC, illustrating the tradeoff
between latency, reliability, and security. We then identify the key
challenging problems for achieving PLS for URLLC, and discuss the role that
channel state information can have in providing potential solutions to these
problems. Finally, we present our recommendations on future research directions
in this emerging area.
