Zero-forcing receive beamforming (ZFRBF) is integrated with signal space diversity (SSD) under an open-loop scenario with binary phase shift keying (BPSK) modulation. First, a dual-stream transmission scheme under a 2-by-M (M >= 2) multiple-input multiple-output scenario is studied. A generalization for any number of simultaneous substreams is then built based on the initial results. We provide an approximation on the average bit error probability (ABEP). We also show that a rotation of pi/4 radian applied on the BPSK signal constellation minimizes the derived approximation on ABEP. It is shown that the error performance of the original ZFRBF scheme can be enhanced by exploiting SSD with only an insignificant increase in complexity and no additional use of bandwidth/time slots.