Abstract: Union upper bound of pairwise-error-probability (PEP) for space-time/frequency block codes in multiple-antenna based orthogonal frequency-division multiplexing (OFDM) systems is derived. And new design considerations were revealed. Then performance comparison between space-frequency block (SFBC) codes, space-time block codes (STBC) and space-time-frequency block codes (STFBC)is performed at different throughput by link-level simulations. The results show that SFBC is superior to STBC in fast fading channel. And power-delay profile of fading channel should be considered for designs of space-time-frequency codes as well as channel orders. SFBC with 4 transmit antenna is robust to both vehicular A and B channel environment of ITU-R M.1225.