Variable Transmit Antenna Selection Using Multimode Scheme for Spatial Multiplexing in MIMO-OFDM Systems

In this paper, we present a new MIMO-OFDM system model with a zero forcing (ZF) receiver for obtaining higher diversity order than a conventional scheme in [1] by selecting the transmit antennas. The difference of the proposed scheme compared to the conventional scheme is that the number of selected transmit antennas may change (i.e., multimode antenna selection scheme) for each subcarrier. When we apply the multimode antenna selection scheme to the MIMO-OFDM system, deciding whether to choose antennas for each subcarrier or for all subcarrier is a primary factor in order to achieve high performance because both cases produce the obviously different result. In the former case, we can obtain the additional diversity order. On the other hand, we can not increase the diversity order compared to conventional scheme in the later case. We verify these results from the bit error rate (BER) performance of both the proposed scheme and the conventional scheme.