Methods, apparatus, and systems for reducing Peak Average Power Ratio (PAPR) in signal transmissions are described. In one example aspect, a wireless communication method includes determining, for an input sequence, an output sequence corresponding to an output of a convolutional modulation between a plurality of values and an intermediate sequence. The intermediate sequence is generated by inserting a set of coefficients between coefficients of the input sequence. Each non-zero coefficient of the set of coefficients is inserted between a first adjacent coefficient and a second adjacent coefficient. Each non-zero coefficient has a power that is between a first power of the first adjacent coefficient and a second power of the second adjacent coefficient and a phase value between a first phase value of the first adjacent coefficient and a second phase value of the second adjacent coefficient. The method also includes generating a waveform using the output sequence.