A method performed by a network infrastructure equipment in a wireless telecommunications system configured to support communications between the network infrastructure equipment and terminal devices (406a; 406b; 406c) using a primary component carrier operating on radio resources within a first frequency band and a secondary component carrier operating on radio resources within a second frequency band, wherein the second frequency band comprises radio resources which are shared with wireless communication devices that are not part of the wireless telecommunications system, wherein the method comprises: transmitting a request message to a plurality of terminal devices to request that at least some of the plurality of terminal devices make measurements of radio channel conditions for radio resources within the second frequency band in accordance with a measurement configuration associated with the request message and transmit measurement reports to the network infrastructure equipment indicating their respective measurements in accordance with the request message; receiving measurement reports from at least some of the plurality of terminal devices indicating their respective measurements of radio channel conditions; and establishing an operating characteristic for the secondary component carrier based on the measurement reports, wherein the wireless telecommunications system supports a connected mode of operation in which terminal devices receive user-plane data from the network infrastructure equipment using the first and / or second component carrier and an idle mode of operation in which terminal devices do not receive user-plane data from the network infrastructure equipment, the method being characterised in that at least one of the plurality of terminal devices to which the request message is transmitted is in the idle mode of operation, and the method further comprises the network infrastructure equipment establishing a radio resource connection with said at least one terminal device so that it switches from the idle mode of operation to the connected mode of operation for transmitting its measurement report to the network infrastructure equipment. transmitting a request message to a plurality of terminal devices to request that at least some of the plurality of terminal devices make measurements of radio channel conditions for radio resources within the second frequency band in accordance with a measurement configuration associated with the request message and transmit measurement reports to the network infrastructure equipment indicating their respective measurements in accordance with the request message; receiving measurement reports from at least some of the plurality of terminal devices indicating their respective measurements of radio channel conditions; and establishing an operating characteristic for the secondary component carrier based on the measurement reports, wherein the wireless telecommunications system supports a connected mode of operation in which terminal devices receive user-plane data from the network infrastructure equipment using the first and / or second component carrier and an idle mode of operation in which terminal devices do not receive user-plane data from the network infrastructure equipment,