  In URLLC the performance of short message communications highly depends on
the training sequence length due to the stringent latency and reliability
requirements. In this paper, we study the performance of cooperative and
non-cooperative transmissions under imperfect channel estimation and Rayleigh
fading for URLLC. We assume a peak power constraint on pilot symbols in
addition to the average power constraint which is used for comparison purposes.
We obtain the optimal training length as a function of blocklength and power
constraint factor to meet the URLLC requirements. Moreover, the simulation
results show the impact of pilot overhead on reliability, latency, and goodput
of cooperative communications compared to pointto-point transmission
