Improvement of CCI and Residual Frequency Offset Compensation Using Feedback Phase Tracking in MIMO-OFDM Systems

Abstract

In multi-input multi-output orthogonal frequency division multiplexing (MIMO-OFDM) systems, phase tracking schemes suffer from co-channel interference (CCI) and inter-carrier interference (ICI) caused by residual frequency offset. In this paper, we propose a residual frequency offset compensation scheme using feedback phase tracking to eliminate the effect of both ICI and CCI for MIMO-OFDM systems. The proposed phase tracking scheme estimates the amount of residual frequency offset in the frequency domain, and compensates for it in the time domain, periodically. Thus, the effect of ICI can be reduced. Furthermore, we consider two methods of channel estimation that enable the system to estimate the channel response several times within a packet to eliminate the effect of CCI. This is because the channel is generally estimated at the beginning of a packet, and this estimation is affected by residual frequency offset. First is the method that employs midambles. Second is the one that reuses the preamble. When the channel is estimated several times within a packet, the effect of CCI can be reduced. Simulation results show the proposed scheme can compensate for residual frequency offset and CCI more accurately than the conventional scheme, and improve the packet error rate (PER) performance.