  Different from conventional wired line connections, industrial control
through wireless transmission is widely regarded as a promising solution due to
its reduced cost, increased long-term reliability, and enhanced reliability.
However, mission-critical applications impose stringent quality of service
(QoS) requirements that entail ultra-reliability low-latency communications
(URLLC). The primary feature of URLLC is that the blocklength of channel codes
is short, and the conventional Shannon's Capacity is not applicable. In this
paper, we consider the URLLC in a factory automation (FA) scenario. Due to
densely deployed equipment in FA, wireless signal are easily blocked by the
obstacles. To address this issue, we propose to deploy intelligent reflecting
surface (IRS) to create an alternative transmission link, which can enhance the
transmission reliability. In this paper, we focus on the performance analysis
for IRS-aided URLLC-enabled communications in a FA scenario. Both the average
data rate (ADR) and the average decoding error probability (ADEP) are derived
under finite channel blocklength for seven cases: 1) Rayleigh fading channel;
2) With direct channel link; 3) Nakagami-m fading channel; 4) Imperfect phase
alignment; 5) Multiple-IRS case; 6) Rician fading channel; 7) Correlated
channels. Extensive numerical results are provided to verify the accuracy of
our derived results.
