Aspects of the disclosure relate to a sidelink signaling mechanism that provides for a combination of single-tone and multiple-tone signaling to reduce overhead, while ensuring reliable signaling. In some examples, a sidelink request signal, such as a source transmit signal (STS), may be a single-tone signal, and a sidelink confirmation signal, such as a destination receive signal (DRS), may be a multiple-tone signal. In other examples, the request signal may be a multiple-tone signal, and the confirmation signal may be a single-tone signal.