A method comprising: a) transmitting, by a first base station, in response to said first base station making a handover decision for a wireless device, at least one first message to at least one second base station, said at least one first message comprising one or more parameters indicating whether said wireless device supports configuration of one or more non-backward compatible carriers being non compatible with a previous standard release; b) receiving, by said first base station and after transmitting said at least one first message, at least one second message from one of said at least one second base station, said at least one second message comprising: i) configuration parameters of a plurality of carriers for said wireless device, said plurality of carriers comprising: at least one backward compatible carrier; and at least one non-backward compatible carrier, a first common reference signal overhead of each of said at least one non-backward compatible carrier being substantially lower than a second common reference signal overhead of each of said at least one backward compatible carrier; ii) information identifying a carrier type for each of said plurality of carriers, said carrier type being one of a backward compatible type and a non-backward compatible type; and iii) information associating each of said at least one non-backward compatible carrier with one of said at least one backward compatible carrier; and c) transmitting, by said first base station, in response to receiving said at least one second message, a third message to said wireless device, said third message comprising said configuration information of said at least one non-backward compatible carrier. a) transmitting, by a first base station, in response to said first base station making a handover decision for a wireless device, at least one first message to at least one second base station, said at least one first message comprising one or more parameters indicating whether said wireless device supports configuration of one or more non-backward compatible carriers being non compatible with a previous standard release; b) receiving, by said first base station and after transmitting said at least one first message, at least one second message from one of said at least one second base station, said at least one second message comprising: i) configuration parameters of a plurality of carriers for said wireless device, said plurality of carriers comprising: at least one backward compatible carrier; and at least one non-backward compatible carrier, a first common reference signal overhead of each of said at least one non-backward compatible carrier being substantially lower than a second common reference signal overhead of each of said at least one backward compatible carrier; ii) information identifying a carrier type for each of said plurality of carriers, said carrier type being one of a backward compatible type and a non-backward compatible type; and iii) information associating each of said at least one non-backward compatible carrier with one of said at least one backward compatible carrier; and i) configuration parameters of a plurality of carriers for said wireless device, said plurality of carriers comprising: at least one backward compatible carrier; and at least one non-backward compatible carrier, a first common reference signal overhead of each of said at least one non-backward compatible carrier being substantially lower than a second common reference signal overhead of each of said at least one backward compatible carrier; at least one backward compatible carrier; and at least one non-backward compatible carrier, a first common reference signal overhead of each of said at least one non-backward compatible carrier being substantially lower than a second common reference signal overhead of each of said at least one backward compatible carrier; ii) information identifying a carrier type for each of said plurality of carriers, said carrier type being one of a backward compatible type and a non-backward compatible type; and iii) information associating each of said at least one non-backward compatible carrier with one of said at least one backward compatible carrier; and c) transmitting, by said first base station, in response to receiving said at least one second message, a third message to said wireless device, said third message comprising said configuration information of said at least one non-backward compatible carrier.