Design of optimal orthogonal linear codes in MIMO systems for MMSE receiver

In this paper, we present a design of linear codes which improves the bit error rate (BER) performance for multiple-input multiple-output (MIMO) communication systems, under a flat-fading environment, in which the channel information is unknown for the transmitter but known at the receiver. Recently, space-time codes have been designed to achieve capacity and/or minimize the overall mean square error. Our codes here simultaneously achieve the lower bound of BER, the upper bound of the overall signal to interference plus noise ratio (SINR) and the lower bound of substream minimum mean square error. Our code structure is orthogonal in both overall and individual senses.