  This paper investigates the effective capacity of a point-to-point
ultra-reliable low latency communication (URLLC) transmission over multiple
parallel sub-channels at finite blocklength (FBL) with imperfect channel state
information (CSI). Based on reasonable assumptions and approximations, we
derive the effective capacity as a function of the pilot length, decoding error
probability, transmit power and the sub-channel number. Then we reveal
significant impact of the above parameters on the effective capacity. A
closed-form lower bound of the effective capacity is derived and an alternating
optimization based algorithm is proposed to find the optimal pilot length and
decoding error probability. Simulation results validate our theoretical
analysis and show that the closed-form lower bound is very tight. In addition,
through the simulations of the optimized effective capacity, insights for pilot
length and decoding error probability optimization are provided to evaluate the
optimal parameters in realistic systems.
