Frequency domain equalization for single-carrier broadband wireless systems
IEEE Communications Magazine
A simple transmit diversity technique for wireless communications
IEEE Journal on Selected Areas in Communications
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In 3GPP LTE-Advanced, open-loop transmit diversity schemes for the uplink are of great interest. It seems that, space-frequency block code (SFBC), the diversity scheme already adopted in the downlink of LTE Release-8, would be a natural option. However, when applying SFBC directly to the uplink, the resulting waveform at one transmit antenna becomes multi-carrier like with higher peak to average power ratio (PAPR), which limits the power efficiency of the corresponding power amplifier (PA). Another option will be to apply conventional space-time block code (STBC) scheme over two consecutive single-carrier frequency-division multiplexing (SC-FDM) symbols. But in some cases, one uplink slot contains an odd number of data SC-FDM symbols, then the last data symbol in the slot will become an orphan symbol over which the conventional STBC will not work. Hence, we want to find a transmission scheme that operates on a single SC-FDM symbol and is able to achieve similar diversity performance as SFBC. Meanwhile, we would like to preserve single-carrier waveform at both transmit antennas to maximize the PA efficiency. To meet this end, we propose a novel transmission scheme: "One Symbol STBC" that operates on a single SC-FDM symbol and can achieve full transmit diversity. Meanwhile, the single-carrier waveform requirement is fulfilled at both transmit antennas. In addition to theoretical justifications, link-level simulations are also carried out which proves our proposed "One Symbol STBC" indeed achieves similar diversity performance as SFBC while maintaining single-carrier waveform's low PAPR.