A radio access network (20) comprises a serving base station (28S) configured to control a serving cell (34S) in an active set of a wireless terminal (30) as well as a non-serving base station (28N) configured to control a non-serving cell (34N) in the active set of the wireless terminal (30). Methods and apparatus are provided for signaling, to the non-serving base station (28N), information indicating a subset of active carriers in the set of at least two carriers.