Universal space-time-frequency block codes design for the multiband MIMO-OFDM systems

In this paper, we study the universal optimal STF block codes design for the MIMO- OFDM systems under the IEEE 802.15.3a UWB channel model. We provide a design criterion, an efficient searching algorithm for the optimal STF block codes, and optimal BER performance curves. Among our proposed optimal STF block codes, we find that almost all of them need nonlinear operations. We also find that the BER decreases as CM increases, and increasing the number of transmit antennas does NOT improve the BER performance for the MIMO-UWB systems. This is similar to the case of the uncoded MIMO-UWB systems but opposite to the ST block codes case.