What is DFT-S-OFDM (DFT spread OFDM)?

The Discrete Fourier Transform – spread-OFDM (DFT-s-OFDM) waveform, normalized in LTE uplink. It gives the benefit of a lower PAPR, however it doesn’t defeat the other OFDM negative marks.
In basic DFT-s-OFDM, the information symbols are first distributed with a DFT block, and afterward mapped to the input of an IDFT block. OFDM does not utilize a DFT-spread block and the symbols are mapped to the subcarriers. Hence, while the RSs are distributed in frequency for OFDM, they are multiplexed in time for DFT-s-OFDM. Therefore, the coexistence of DFT-s-OFDM and OFDM leads to inconsistent overlapping on the equivalent resources.