Blind Estimation of Common Phase Error in OFDM and OFDMA

This paper addresses the issue of blind estimation of common phase error (CPE) in OFDM systems affected by phase noise (PHN). Common approaches to blind CPE detection detect the symbols, and estimate the phase noise in an iterative manner. An important assumption that these decision-directed algorithms make is that a majority of the symbols detected in the first iteration, while ignoring the presence of phase noise, have been detected correctly. This assumption fails to hold under scenarios of high CPE and leads to a premature error floor. In this paper we dispense with the assumption that most of the symbols have been detected correctly and instead associate with each symbol a certain probability of having been detected correctly. Through the introduction of an auxiliary binary variable that indicates whether the right decision on a symbol has been made or not, we design a new algorithm to estimate CPE. This algorithm is robust to high CPE scenarios and is able to lower the error floor seen at high SNRs.