Distributed antenna system using RAKE combining diversity for a multi-carrier DS/CDMA in a frequency selective fading channel

DS/CDMA suffers from ISI (intersymbol interference) caused by the multipath propagation in a frequency selective fading channel, it greatly deteriorates BER performance. Since multi-carriers have high correlations among subcarriers with one antenna, it does not have enough diversity gain. In this paper, we propose a combined system with path diversity gain of the distributed antennas and frequency diversity gain of multicarrier. The base station consists of the distributed antennas, whose multi-carriers are effective for the robustness against ISI and ICI in frequency selective channel fading, because each carrier has non-frequency selective channel fading. It is assigned to several sub-carriers for each antenna. A set of antennas are fed by a common signal with time delay processing to the de-correlated signals. It creates a path diversity effect with multi-carriers for each antenna which can be combined by a RAKE receiver. As a result, we can obtain effective combined path diversity and frequency diversity gain by the RAKE combining of distributed antennas.