Methods and apparatuses are described for the transmission of Scheduling Assignments (SAs) from a base station to User Equipments (UEs) for data reception in the downlink or data transmission in the uplink of a communication system consisting of multiple Component Carriers (CCs). The SAs are separately coded and transmitted using elementary units (Control Channel Elements or CCEs). Locations of CCEs determine whether an SA is intended for a first CC or for a second CC. Further, the location of CCEs for an SA intended for a first CC is used to determine locations of CCEs for an SA intended for a second CC.