The present invention relates to methods and devices for use in multi carrier communication systems in which secondary downlink and secondary uplink carriers may be dynamically activated/deactivated by means of transmitting an HS-SCCH order from a radio base station to a user equipment. The HS-SCCH order is encoded by the radio base station according to an order mapping. The order mapping maps a desired activation status of a set of carriers to a corresponding encoded HS-SCCH order. The user equipment interprets the encoded HS-SCCH order to derive the desired activation status of the set of carriers. By using an appropriate order mapping, operations in the radio base station and/or the user equipment may be simplified, e.g. by allowing the radio base station to calculate the encoded HS-SCCH order based on the desired activation status.