In this paper, we develop a novel STBC for multi-antenna transmissions over doubly-selective channels. The proposed STBC is designed

for a multiple-input single-output (MISO) system with two transmit

antennas and one receive antenna, i.e., a 2 1 system, but the ideas

can be extended to a general multiple-input multiple-output (MIMO)

system. The proposed technique can be interpreted as the extension

of the Alamouti code to doubly-selective channels, and relies on a

joint time–frequency reversal of the transmitted sequences.