Designing low-complexity detectors for generalized SC-FDMA systems

Single carrier frequency division multiple access (SC-FDMA) is proposed to alleviate the high peak-to-average power ratio (PAPR) issue in orthogonal frequency division multiple access (OFDMA) transmissions. However, the SC-FDMA transmission does not fully exploit the multipath diversity provided by frequency-selective channel, where only diversity one can be collected even with maximum-likelihood detector. In this paper, we propose generalized SC-FDMA (GSC-FDMA) transmissions to enable the multipath diversity with low-complexity lattice-reduction (LR) aided linear detectors. Additionally, we develop a new LR algorithm which improves the asymptotic performance of linear detectors and achieves lower complexity than the well known existing LR-aided ones. The improved bit-error-rate (BER) performance relative to SC-FDMA systems is studied in simulations, where the significant gain of the LR-aided detectors is found for higher order constellations (16QAM and 64QAM).