LTE上行为什么非要DFT之后再IFFT，为何不直接发送时域信号

lubeeli

The important properties of the SC-FDMA transmission scheme used for the LTE uplink
are derived from its multicarrier OFDM-like structure with single-carrier characteristic. The
multicarrier-based structure gives the LTE uplink the same robustness against ISI as the LTE
downlink, with low-complexity frequency-domain equalization being facilitated by the CP.

At the same time, the DFT-based precoding ensures that the LTE uplink possesses the low CM(PARP)
required for efficient UE design.

Crucially, the LTE uplink is designed to be orthogonal in the frequency domain between different UEs, thus virtually eliminating the intra-cell interference associated with CDMA.