Systems, methods, apparatuses, and computer program products for enhancing the setup of carrier aggregation (or dual connectivity or multi connectivity or stand-alone LTE/LTE-like on unlicensed band or LAA or LTE-WLAN aggregation) from IDLE mode (or semi-idle or semi-connected or suspended state) are provided. One method includes providing an indication, to at least one UE, of (or configuring the UE with) potential inter-frequency carriers that the UE should measure during IDLE mode (or during semi-idle or semi-connected or suspended state) for potential SCells. The method may further include during or after RRC connection establishment, receiving an indication from the at least one UE that it has inter-frequency carrier(s) and/or SCell measurement results available, and based on the received measurement results, configuring carrier aggregation (or dual connectivity or multi connectivity or LAA or LTE-WLAN aggregation) without further measurements and activating the SCell.