Maximum signal-to-noise ratio array processing for space-time coded systems

We consider the design of array processor for space-time coded multi-antenna systems. While the zero-forcing method was employed by Tarokh, Naguib, Seshadri and Calderbank (see IEEE Transactions on Information Theory, vol.45, no.4, p.1121-28, 1999), in this paper we seek to obtain a balance between interference suppression and noise enhancement. Although same in concept, this work differs from the conventional minimum mean square error (MMSE) method in that there are more than one desired signal dimensions each corresponding to one of the space-time coded streams. In this case, minimizing the mean squared error (MSE) involves averaging over data modulation and may complicate the presentation. Instead, maximizing the signal-to-noise ratio (SNR) can be handled more concisely. It will be shown that the number of linear filters required by the maximum SNR array processor is no more than the dimension of the signal space or the number of collaborating transmit antennas. The advantages of this design are highly improved performance and reduced decoding complexity