  Achieving ultra-reliable, low-latency and secure communications is essential
for realizing the industrial Internet of Things (IIoT). Non-coherent massive
multiple-input multiple-output (MIMO) is one of promising techniques to fulfill
ultra-reliable and low-latency requirements. In addition, physical layer
authentication (PLA) technology is particularly suitable for secure IIoT
communications thanks to its low-latency attribute. A PLA method for
non-coherent massive single-input multiple-output (SIMO) IIoT communication
systems is proposed in this paper. This method realizes PLA by embedding an
authentication signal (tag) into a message signal, referred to as
"message-based tag embedding". It is different from traditional PLA methods
utilizing uniform power tags. We design the optimal tag embedding and optimize
the power allocation between the message and tag signals to characterize the
trade-off between the message and tag error performance. Numerical results show
that the proposed message-based tag embedding PLA method is more accurate than
the traditional uniform tag embedding method which has an unavoidable tag error
floor close to 10%.
