According to an example aspect of the present disclosure, there is provided an apparatus comprising at least one processing core and at least one memory storing instructions that, when executed by the at least one processing core, cause the apparatus at least to determine a bit sequence, divide the bit sequence into fragments of bits, map each fragment of bits to a different orthogonal frequency division multiplexed (OFDM) symbol, encode the fragments using on-off keying or frequency shift keying manipulate the encoded fragments to obtain a cyclic signal for each OFDM symbol and transmit a wakeup signal comprising the manipulated fragments.