  This paper addresses the issue of phase noise in OFDM systems. Phase noise
(PHN) is a transceiver impairment resulting from the non-idealities of the
local oscillator. We present a case for designing a turbo receiver for systems
corrupted by phase noise by taking a closer look at the effects of the common
phase error (CPE). Using an approximate probabilistic framework called
variational inference (VI), we develop a soft-in soft-out (SISO) algorithm that
generates posterior bit-level soft estimates while taking into account the
effect of phase noise. The algorithm also provides an estimate of the phase
noise sequence. Using this SISO algorithm, a turbo receiver is designed by
passing soft information between the SISO detector and an outer forward error
correcting (FEC) decoder that uses a soft decoding algorithm. It is shown that
the turbo receiver achieves close to optimal performance.
