Suppression of carrier frequency offset and phase noise in adaptive bit loading OFDM system

Introduce adaptive bit loading technique into orthogonal frequency division multiplexing (OFDM) system can highly improve system performance in frequency selective fading channel. However, similar with ordinary OFDM system, this system is very sensitive to carrier frequency offset (CFO) and phase noise. When CFO and phase noise exist, common phase error (CPE) as well as inter carrier interference (ICI) will be generated to disturb the received signal and system performance will be seriously degraded. In this paper, we analyze the interferences caused by CFO and phase noise in adaptive bit loading OFDM system when the channel condition is frequency selective fading channel. Then the suppression method based on block type pilots is introduced to overcome the interferences simultaneously. From the simulation results, it can be seen that CFO and phase noise will cause serious system performance degradation. But after we perform the suppression processing, system performance can be significantly improved.