Phase Noise Suppression in OFDM with Spatial Multiplexing

A very promising way to achieve high spectral efficiency in wireless communication is the use of multiple transmit and receive antennas. However, in combination with multicarrier modulation, e.g. MIMO-OFDM, the performance of such a system can be drastically limited due to the existence of RF imperfections such as oscillator phase noise. Many methods for phase noise compensations in a single antenna environment have been developed, whereas only a few deal with the problem in a MIMO case. Those contributions mainly discuss the common phase error (CPE) correction. In this work we extend the CPE correction and perform a linear minimum mean square error (LMMSE) estimation of higher order phase noise harmonics in order to compensate intercarrier interference (ICI) in a multi antenna system. In a coded multi antenna environment it is common to perform detector-decoder iterations which lead to an improved performance behavior. During the iterations we use the a-priori knowledge provided by the decoder to improve the phase noise estimation. This is done by using only the most reliable symbols for performing the LMMSE estimate. As for the detection we use a simple MMSE equalizer where we use the general expression and adapt the noise covariance matrix according to the remaining ICI. Finally the performance is shown by simulation results for an IEEE 802.11n E channel.