A method includes obtaining a reference signal waveform (b, b1-b5) which is defined in accordance with a non-coherent modulation scheme. The method also includes—shaping the reference signal waveform (b, b1-b5) to obtain at least one signal waveform (x˜) associated with one or more subcarriers (K) of a plurality of subcarriers (301-303). The method further includes inputting the at least one signal waveform to at least one corresponding channel (1552) of a multi-channel orthogonal frequency division multiplex, OFDM, modulator (F, 1502, 1503, 1504) and transmitting an OFDM symbol (s) output by the OFDM modulator (F, 1502, 1503, 1504).