  In this letter, we analyze the achievable rate of ultra-reliable low-latency
communications (URLLC) in a randomly modeled wireless network. We use two
mathematical tools to properly characterize the considered system: i)
stochastic geometry to model spatial locations of the transmitters in a
network, and ii) finite block-length analysis to reflect the features of the
short-packets. Exploiting these tools, we derive an integral-form expression of
the decoding error probability as a function of the target rate, the path-loss
exponent, the communication range, the density, and the channel coding length.
We also obtain a tight approximation as a closed-form. The main finding from
the analytical results is that, in URLLC, increasing the signal-to-interference
ratio (SIR) brings significant improvement of the rate performance compared to
increasing the channel coding length. Via simulations, we show that fractional
frequency reuse improves the area spectral efficiency by reducing the amount of
mutual interference.
