Abstract: A design method for the space-time block code(STBC) with pre-coding is proposed to utilize both space diversity and time diversity. The constellations are rotated first. Then the L-dimension signal vector a is transformed to a new vector x, which is divided into L/2 sub-vectors. These L/2 sub-vectors are used to construct the signal matrix and transmitted via two antennas one by one. When m receive antennas are fixed, the diversity achieved by the pre-coding STBC in Lm, which is L/2 times that of the traditional methods over quasi-static flat fading channels. Compared with the space-time trellis code(STTC), the Pre-coding STBC has lower complexity without performance deterioration.

Key words: pre-coding, space-time block code, constellation-rotating matrix, diversity gains