Adaptive Spatial Mode of Space-Time and Space-Frequency OFDM System over Fading Channels

In this paper we present a 2 transmit 1 receive (1 tx : 1 rx) adaptive spatial mode (asm) of space-time (st) and space-frequency (sf) orthogonal frequency division multiplexing (ofdm). at low signal to noise ratio (snr) we employ st-ofdm and switch to sf-ofdm at a certain snr threshold. we determine this threshold from the intersection of individual performance curves. results show a gain of 9 db (at a bit error rate of 10-3) is achieved by employing adaptive spatial mode compared to a fixed st-ofdm, almost 6 db to fixed sf-ofdm, 4 db to coded st-ofdm and 2 db to a fixed coded sf-ofdm, at a delay spread of 700 ns.