A method including receiving, by a user device from a network node, a configuration including at least an indication to perform spectrum extension; determining a target extension factor for excess band frequency resources for a target spectrum extension; receiving information indicating a set of inband frequency resources allocated to the user device for uplink transmission; determining, by the user device based on the set of inband frequency resources and the target extension factor, the excess band frequency resources for the spectrum extension and/or a total allocation of frequency resources for uplink transmission, wherein the total allocation of frequency resources includes the inband frequency resources and the excess band frequency resources; performing, by the user device, a spectrum extension based on the excess band frequency resources for a set of frequency domain values, to obtain a spectrum extended signal; and transmitting the spectrum extended signal.