On space-time code design with a conditional PIC group decoding

Space-time code designs based on a partial interference cancellation (PIC) group decoding have been recently proposed. The PIC group decoding complexity depends on the group size and is between the lowest linear receiver complexity and the highest ML decoding complexity. The symbol rate for a space-time code achieving full diversity with the PIC group decoding is also between those for the linear receivers and the ML decoding. In this paper, we propose a new decoding, called conditional PIC group decoding, that is between the PIC group decoding and the ML decoding. With the proposed new decoding, we obtain a new design criterion for space-time codes to achieve full diversity, which is also between the one with the PIC group decoding and the one with the ML decoding. We then present some designs that satisfy the new criterion and in the meantime have higher symbol rates than that for the PIC group decoding.