Methods and devices are provided whereby scrambling codes can be set in an improved way. In accordance with one embodiment a method is provided in a User Equipment for generating a second scrambling code or a second scrambling code group. The UE is configured for multi carrier operation receiving downlink transmission from a Universal Mobile Telecommunications System Terrestrial Radio Access Network on a set of at least two downlink carriers including an anchor carrier and at least a first secondary carrier. The method comprises determining a first scrambling code or a first scrambling code group associated with a first cell on the anchor carrier; and deriving a second scrambling code or a second scrambling code group associated with a second cell on said first secondary carrier using a predefined rule defining the relation between the second scrambling code or second scrambling code group and the first scrambling code or scrambling code group. Hereby interference suppression/cancellation processing is enabled in a receiver of a UE on secondary cells in multi-carrier scenarios that do not transmit the SCH, while minimizing the need for overhead in terms of signaling of the scrambling codes for neighbouring cells in a UTRAN system. Methods and devices for E-UTRAN are also described.