A method of providing a wake-up signal in a communications channel for a plurality of receiving stations, the method performed by a transmitter, the method comprising: generating a plurality of series of waveform coded symbols, each series being incorporated into a respective wake-up-radio, WUR, frame that is intended for a respective receiving station and has a respective predefined bandwidth; combining the respective WUR frames into a multiband WUR data unit having a bandwidth that is greater than a sum of the predefined bandwidths of the WUR frames; transmitting a wake-up signal including the multiband WUR data unit in the communications channel; wherein each of the waveform coded symbols represents a respective data bit and comprises a guard interval followed by first and second sub-symbols of equal duration, the corresponding data bit being represented by a different relative energy distribution between the first and second sub-symbols; wherein the plurality of series of waveform coded symbols includes a first series incorporated into a first WUR frame that has a first predefined bandwidth, a second series incorporated into a second WUR frame that has a second predefined bandwidth, and a third series incorporated into a third WUR frame that has a third predefined bandwidth, wherein each waveform coded symbol in the first series is generated from applying waveform coding in time domain to a first orthogonal frequency division multiplexing, OFDM, waveform for which all subcarriers outside of the first predefined bandwidth have been set to zero; wherein each waveform coded symbol in the second series is generated from applying waveform coding in time domain to a second OFDM waveform for which all subcarriers outside of the second predefined bandwidth have been set to zero; wherein each waveform coded symbol in the third series is generated from applying waveform coding in time domain to a third OFDM waveform for which all subcarriers outside of the third predefined bandwidth have been set to zero; and wherein combining the respective WUR frames into the multiband WUR data unit comprises adding the first, second and third WUR frames in a synchronized sample-by-sample manner using the same sampling rate as that used in generating each waveform coded symbol to generate the multiband WUR data unit, and the method further comprises up-converting the multiband WUR data unit to provide the wake-up signal. generating a plurality of series of waveform coded symbols, each series being incorporated into a respective wake-up-radio, WUR, frame that is intended for a respective receiving station and has a respective predefined bandwidth; combining the respective WUR frames into a multiband WUR data unit having a bandwidth that is greater than a sum of the predefined bandwidths of the WUR frames; transmitting a wake-up signal including the multiband WUR data unit in the communications channel; wherein each of the waveform coded symbols represents a respective data bit and comprises a guard interval followed by first and second sub-symbols of equal duration, the corresponding data bit being represented by a different relative energy distribution between the first and second sub-symbols; wherein the plurality of series of waveform coded symbols includes a first series incorporated into a first WUR frame that has a first predefined bandwidth, a second series incorporated into a second WUR frame that has a second predefined bandwidth, and a third series incorporated into a third WUR frame that has a third predefined bandwidth, wherein each waveform coded symbol in the first series is generated from applying waveform coding in time domain to a first orthogonal frequency division multiplexing, OFDM, waveform for which all subcarriers outside of the first predefined bandwidth have been set to zero; wherein each waveform coded symbol in the second series is generated from applying waveform coding in time domain to a second OFDM waveform for which all subcarriers outside of the second predefined bandwidth have been set to zero; wherein each waveform coded symbol in the third series is generated from applying waveform coding in time domain to a third OFDM waveform for which all subcarriers outside of the third predefined bandwidth have been set to zero; and wherein combining the respective WUR frames into the multiband WUR data unit comprises adding the first, second and third WUR frames in a synchronized sample-by-sample manner using the same sampling rate as that used in generating each waveform coded symbol to generate the multiband WUR data unit, and the method further comprises up-converting the multiband WUR data unit to provide the wake-up signal.