Space-time coded decorrelating RAKE receiver for fast fading CDMA channels

This paper presents a decorrelating RAKE (DRAKE) receiver utilizing multiple transmit antennas and space-time block coding (STBC), for code-division multiple-access (CDMA) systems in fast fading channels. A linear blind multiuser receiver for slowly fading CDMA channels, which is known as the decorrelating RAKE receiver, was proposed by Liu and Li (IEEE Trans. Commun., vol.47, p.1036-1045, 1999) previously. This DRAKE receiver was subsequently extended to a fast fading channel environment, where a Kalman filter was employed to estimate the channel impulse response adaptively. Motivated by the success of the space-time coding technique in high-speed data transmission, we propose in this paper a new space-time coded DRAKE receiver for fast fading channels in order to increase the system capacity. The proposed receiver exploits the spatial diversity by adopting multiple transmit antennas and STBC techniques. Simulation results show that the performance of the proposed receiver is also close to the MMSE receiver with known channel state information (CSI).