  This paper deals with the phase noise affecting communication systems, where
local oscillators are employed to obtain reference signals for carrier and
timing synchronizations. The most common discrete-time phase noise channel
model is analyzed, with the aim to fill the gap between measurements and
analytical models. In particular, the power loss and the intersymbol
interference due to the presence of phase noise is evaluated with reference to
the measurements parameters and to the system bandwidth. Moreover, the impact
on the communication systems' performance of the phase noise originating from
the oscillator non idealities is considered, in case of free-running and
phase-locked oscillators. The proposed analysis allows to extrapolate useful
information about the performance of practical systems by investigating the
power spectral density of the oscillator phase noise. An expression for the
variance of the residual phase error after tracking, which depends on the main
parameters of practical oscillators, is derived, and used to study the
dependence of the performance on the symbol rate.
