A serving base station transmits at least one message to configure at least one backward compatible carrier and at least one non-backward compatible carrier in a wireless device. The serving base station transmits, in response to the serving base station making a handover decision, a second message to a target base station. The second message comprises parameters indicating whether the wireless device supports configuration of non-backward compatible carriers, configuration information of at least one backward compatible carrier and/or configuration information of at least one non-backward compatible carrier.