Methods, apparatuses, and computer program products are disclosed for facilitating indicating and detecting control region sizes. A multi-carrier communication between a wireless terminal and a base station is facilitated by a first carrier having a first control region size and a second carrier having a second control region size. Embodiments are disclosed in which control region sizes are ascertained from a control signal, wherein the control is generated by either scrambling an aspect of the control signal based on the second control region size, or relating the second control region size with the first control region size. Other disclosed embodiments for ascertaining control region sizes include a reverse interleaver embodiment, wherein a set of modulation symbols is mapped beginning from a last data symbol and ending with a first available data symbol.