In this paper, a DFT-based frequency-domain spread spectrum (FDSS) technique for SC transmission is introduced. The transmitted data is initially transformed to frequency-domain signal by using DFT. Frequency-domain spreading can achieve large frequency diversity gain through joint frequency-domain equalization (FDE) and spectrum combining. Performance of the proposed FDSS is evaluated by computer simulation in aspects of bit-error rate (BER), peak-to-average power ratio (PAPR), and average throughput, and then compared to the conventional TDSS scheme with spreading sequence.