A method of operating a terminal device and network infrastructure equipment in a wireless telecommunications system for communicating on a primary cell supporting a primary component carrier on radio resources within a first frequency band and a secondary cell supporting a secondary component carrier on radio resources within a second frequency band. The infrastructure equipment establishes a plurality of configuration settings for the secondary carrier (e.g. in terms of frequency and / or time resources) based on measurements of radio usage in the second frequency band. The configuration settings are conveyed to the terminal device. The terminal device makes channel quality measurements for the secondary component carrier according to the different configuration settings and reports these to the infrastructure equipment. Based on these measurements of channel quality for the different configurations of the secondary carrier, the infrastructure equipment selects one of the configuration settings, and conveys an indication of this to the terminal device in association with an allocation of transmission resources on the secondary component carrier. Data is then transmitted from the infrastructure equipment to the terminal device using the allocated resources on the secondary component carrier with the secondary component carrier operating in accordance with the selected configuration.