An Optimal PIC Group Decoding for Layered Alamouti Code in Two-User Case

Partial interference cancellation (PIC) group decoding is an attractive method to reduce the maximum-likelihood (ML) decoding complexity of a layered Alamouti code. However, different grouping schemes for the PIC group decoding may have different performances. In this paper, by fully taking advantage of the Alamouti code structure, we analytically calculate the power gains of the information symbols after the PIC for a grouping scheme. We then propose an optimal grouping scheme for the PIC group decoding by proposing a criterion to choose the grouping schemes adaptively so that the power gains of the information symbols are maximized after the PIC.