A method comprising: transmitting, from a base station (104, 300) to a user equipment, UE, (106, 108, 110, 200), measurement configuration information via a licensed frequency band, wherein the measurement configuration information is information to instruct the UE (106, 108, 110, 200) to perform measurements on an unlicensed frequency band; performing measurements, at the UE (106, 108, 110, 200), on the unlicensed frequency band in response to receiving the measurement configuration information from the base station (104, 300), wherein the measurements include at least a measurement of Received Signal Strength Indicator, RSSI, values of the unlicensed frequency band; determining if the RSSI values are beyond a first threshold; transmitting, from the UE (106, 108, 110, 200) to the base station (104, 300), measurement results, wherein the measurement results include the RSSI values and a result of the determination; receiving, at the base station (104, 300), the measurement results from the UE (106, 108, 110, 200); assigning, at the base station (104, 300), resources of the unlicensed frequency band for communication with the UE (106, 108, 110, 200); transmitting (906, 914), from the base station (104, 300) to the UE (106, 108, 110, 200), resource information indicating the resources of the unlicensed frequency band for communication between the base station (104, 300) and the UE (106, 108, 110, 200), based on the measurement results; transmitting, from the base station to the UE, information specifying either a first mode or a second mode, based on the measurement results; wherein in the first mode the UE performs a first monitoring of the unlicensed frequency band to determine whether the unlicensed frequency band is in use; and wherein in the second mode the UE performs a second monitoring of the unlicensed frequency band to determine whether the unlicensed frequency band is in use, the second monitoring being a reduced monitoring compared to the first monitoring. transmitting, from a base station (104, 300) to a user equipment, UE, (106, 108, 110, 200), measurement configuration information via a licensed frequency band, wherein the measurement configuration information is information to instruct the UE (106, 108, 110, 200) to perform measurements on an unlicensed frequency band; performing measurements, at the UE (106, 108, 110, 200), on the unlicensed frequency band in response to receiving the measurement configuration information from the base station (104, 300), wherein the measurements include at least a measurement of Received Signal Strength Indicator, RSSI, values of the unlicensed frequency band; determining if the RSSI values are beyond a first threshold; transmitting, from the UE (106, 108, 110, 200) to the base station (104, 300), measurement results, wherein the measurement results include the RSSI values and a result of the determination; receiving, at the base station (104, 300), the measurement results from the UE (106, 108, 110, 200); assigning, at the base station (104, 300), resources of the unlicensed frequency band for communication with the UE (106, 108, 110, 200); transmitting (906, 914), from the base station (104, 300) to the UE (106, 108, 110, 200), resource information indicating the resources of the unlicensed frequency band for communication between the base station (104, 300) and the UE (106, 108, 110, 200), based on the measurement results; transmitting, from the base station to the UE, information specifying either a first mode or a second mode, based on the measurement results; wherein in the first mode the UE performs a first monitoring of the unlicensed frequency band to determine whether the unlicensed frequency band is in use; and wherein in the second mode the UE performs a second monitoring of the unlicensed frequency band to determine whether the unlicensed frequency band is in use, the second monitoring being a reduced monitoring compared to the first monitoring.