Systems, methods, and instrumentalities are disclosed for generating, transmitting, and/or receiving a hybrid spread waveform. The hybrid spread waveform may include a data portion and a hybrid guard interval (HGI) portion. The HGI portion may include a fixed prefix portion or a fixed suffix portion, and an adaptive low power tail (LPT) portion. The fixed prefix portion or the fixed suffix portion is a low power cyclic prefix (LPCP). The LPCP may be generated at least based on at least the channel delay spread and a power regrowth length. The adaptive LPT portion may be generated using a zero tail (ZT). The LPT is generated by inserting zeros at IFFT or DFT processing stage. A part of the adaptive LPT portion is used to carry data or control information. A waveform may be switched between a hybrid spread waveform and a fixed-CP waveform, e.g., via control signaling.