Embodiments are provided for guard band utilization for synchronous and asynchronous communications in wireless networks. A user equipment (UE) or a network component transmits symbols on data bands assigned for primary communications. The data bands are separated by a guard band having smaller bandwidth than the data bands. The UE or network component further modulates symbols for secondary communications with a spectrally contained wave form, which has a smaller bandwidth than the guard band. The spectrally contained wave form is achieved with orthogonal frequency-division multiplexing (OFDM) modulation or with joint OFDM and Offset Quadrature Amplitude Modulation (OQAM) modulation. The modulated symbols for the secondary communications are transmitted within the guard band.