ISI and ICI Suppression for Mobile OFDM System by Using a Hybrid 2-Layer Diversity Receiver

An OFDM system is very sensitive to orthogonality relation. For a mobile wireless system, it is impossible to avoid Doppler-induced inter carrier interference (ICI). Moreover, while beyond guard interval delayed signal exists in channel, the delay-induced ICI and inter symbol interference (ISI) will occur. Although a conventional carrier diversity (CD) receiver can render the OFDM system less sensitive to the whitenoise-likely ICI, but it requires significant channel knowledge. On the other hand, a pre-FFT adaptive array (AA) receiver can improve the instantaneous signal to interference-and-noise ratio (SINR) at the input of FFT. In this paper, a hybrid AA/CD two layers receiver is investigated not only on a tradeoff between high performance and low complexity, but also into a method for both ISI and ICI suppression. Simulation results show that a suitable combination of pre-FFT AA and post-FFT CD can provide good performance by comparison with conventional OFDM receiver in mobile wireless channel, especially, while ISI and ICI occur at the same time.