This invention relates to a proposal of an uplink resource assignment format and a downlink resource assignment format. Furthermore, the invention relates to the use of the new uplink/downlink resource assignments in methods for (de) activation of downlink component carrier (s) configured for a base station and a mobile terminal. To enable efficient and robust (de) activation of component carriers, while minimizing the signaling overhead, the invention proposes a new uplink/downlink resource assignment format that allow the activation/deactivation of individual downlink component carriers configured for a mobile. The new uplink or downlink resource assignment comprises an indication of the activation state of the configured downlink component carriers, i.e. indicate which downlink component carrier (s) is/are to be activated or deactivated. This indication is for example implemented by means of a bit-mask that indicates which of the configured uplink component carriers are to be activated respectively deactivated.