Blind adaptive DS/CDMA receivers in multipath fading channels

In order to eliminate multiple-access interference (MAI) and intersymbol interference (ISI) in direct sequence code division multiple access (DS/CDMA) multiuser communication systems, in this paper, we propose several receiver structures and employ the property of the discreteness of the input data symbol to derive the blind algorithms. These proposed adaptive receivers are updated in the symbol-interval so their computational loading is lower than the chip-interval based adaptive receivers. We use the concept that the variance of despreading output approaches the variance of the desired signal to formulate the cost function. We call this new algorithm the variance-oriented approach (VOA). We then apply VOA to several proposed receiver structures. Especially, we apply the generalized sidelobe canceller (GSC) scheme, that is generally the concept of the spatial domain in a beamforming system, to eliminate the MAI by one particular constraint in the temporal domain. Simulation examples are shown to demonstrate the effectiveness and comparison of the proposed blind adaptive receivers.