Many papers have extended STBC design to frequency-selective

channels. In [6], STBC has been proposed for single-carrier transmission, which can achieve maximum space-delay diversity in rich

scattering channels. The transmission formats proposed in [6] subsume

those of [7], [8], which present time-reversal STBC at the transmitter

to achieve transmit diversity. Multicarrier transmission systems have

been considered in [9]–[11]. A space–time–multipath coded system is

developed in [12] using digital phase sweeping (DPS) in the frequency

domain or circular delaying in the time domain, which guarantees

the maximum possible space-delay diversity, and has full rate for any

number of transmit–receive antennas. Note that the aforementioned

algorithms all require the channel to be constant over the entire

space–time codeword