A hybrid adaptive array and carrier diversity receiver for OFDM fading channels -high-performance and low-complexity-

An OFDM system performance is very sensitive to the estimation accuracy of the channel transfer function (CTF) when the scattered pilots were used. Conventional carrier diversity (CD) receiver requires multiple FFT processors and corresponding number of channel estimators according to the increase of the number of diversity antennas. On the other hand, only one FFT processor is need in a pre-FFT antenna array (AA) receiver, and the AA can improve the instantaneous signal-to-interference-and-noise ratio (SINR) at the input of the FFT. As a result, the accuracy of channel estimation can be improved after FFT. In this paper, a hybrid AA/CD receiver´s performance tradeoff with complexity is analyzed. The hybrid receiver can halve the number of the FFT processors by comparing with the conventional CD receiver. Simulation results show that the combination of minimum mean square error (MMSE) AA and equal gain combing (EGC) CD and maximum-ratio combing (MRC) CD scheme can provide better performance in multi-path channel under slow and fast fading.