  In this paper we analyze the effect of the calibration period, or lack of, on
self-interference channel estimation in the digital domain of in-band
full-duplex radio transceivers. In particular, we consider a scenario where the
channel estimation must be performed without a separate calibration period,
which means that the received signal of interest will act as an additional
noise source from the estimation perspective. We will explicitly analyze its
effect, and quantify the increase in the parameter estimation variance, or
sample size, if similar accuracy for the channel estimate is to be achieved as
with a separate calibration period. In addition, we will analyze how the
calibration period, or its absence, affects the overall achievable rates. Full
waveform simulations are then used to determine the validity of the obtained
results, as well as provide numerical results regarding the achievable rates.
It is shown that, even though a substantial increase in the parameter sample
size is required if there is no calibration period, the achievable rates are
still comparable for the two scenarios.
