MIMO decorrelating discrete-time RAKE receiver

In this paper, we introduce a decorrelating discrete-time RAKE receiver for MIMO systems. Conventional RAKE receivers require acquisition and tracking systems to detect new paths and to follow them. To avoid this requirement a discrete-time RAKE receiver (DTR) has been proposed, which is obtained by sampling the received signal at twice the chip rate. The DTR works well in both specular and diffuse multipath channels. A drawback of the DTR is its sensitivity to channel estimation errors. To eliminate this weakness an optimum combining technique has been introduced, called the decorrelating discrete-time RAKE receiver (D-DTR). The D-DTR exploits the covariance matrix of the discrete-time channel for a better robustness against channel estimation errors. In this paper, we extend this system to the MIMO case. Our simulations show that gains up to 2 dB are available in 2 transmit 2 receive antenna and 3 transmit 3 receive antenna systems at a bit error rate of 10.