Although many candidate waveforms have been proposed for 5G, the first phase of NR uses a version of orthogonal frequency division multiplexing (OFDM). The specific version of OFDM used in 5G NR downlink is cyclic prefix—OFDM is the same waveform LTE has adopted for the downlink signal. However, unlike LTE, 5G NR also uses CP-OFDM- and DFT-S-OFDM-based waveforms in the uplink. Also unlike LTE, 5G NR allows for significant variation in subcarrier spacing. Whereas LTE subcarriers were almost always spaced at 15 kHz, 5G NR allows a flexible scheme where subcarriers are spaced at 15 kHz x 2n. In 5G NR, the maximum subcarrier spacing allowed is 240 kHz, and it is reserved for the scenario where 400 MHz carrier bandwidth is used.