Pre-DFT Tomlinson-Harashima Precoding for SC-FDMA

There is considerable interest in the use of Single Carrier Frequency Division Multiple Access (SC-FDMA) as the uplink transmission scheme in the 3GPP Long Term Evolution standard. In this paper a pre-DFT time-domain implementation of Tomlinson-Harashima Precoding (THP) for uplink SC-FDMA is proposed. We demonstrate how precoding the uplink transmission is an alternative signal processing technique to equalization in order to combat the frequency selective nature of the propagation channel. We investigate the BER performance and PAPR characteristics of the precoded SC-FDMA waveform for ZF and MMSE criterion. Results reported here show that MMSE-THP offers a gain of 3-4 dB in SNR over a DFE with ideal feedback and approaches the matched filter bound.