  Modern wireless machine-to-machine-type communications aim to provide both
ultra reliability and low latency, stringent requirements that appear to be
mutually exclusive. From the noisy channel coding theorem, we know that
reliable communications mandate transmission rates that are lower than the
channel capacity. To guarantee arbitrarily-low error probability, this implies
the use of messages whose lengths tend to infinity. However, long messages are
not suitable for low-latency communications. In this paper, we propose an
early-detection scheme for wireless communications under a finite-blocklength
regime that employs a sequential-test technique to reduce latency while
maintaining reliability. We prove that our scheme leads to an average detection
time smaller than the symbol duration. Furthermore, in multi-hop low-traffic or
continuous-transmission links, we show that our scheme can reliably detect
symbols before the end of their transmission, significantly reducing the
latency, while keeping the error probability below a predefined threshold.
