A base station in a communication system providing at least three cells from the base station , the base station adapted to: communicate with a first user equipment , using at least two cells by carrier aggregation; provide, to the first user equipment , a first cell (CC1) among the at least two cells as a first special cell to keep connection between the base station and the first user equipment ; provide a second cell (CC2) among the at least two cells for use for the first user equipment as uplink and/or downlink resources: communicate with a second user equipment using the at least three cells by the carrier aggregation; provide, to the second user equipment , a third cell (CC3) among the at least three cells as a second special cell to keep connection between the base station and the second user equipment ; and provide the first cell (CC1) and the second cell (CC2) for use for the second user equipment as uplink and/or downlink resources, the second cell (CC2) and the third cell (CC3) being different from the first cell (CC1), wherein, when system information used for the second cell (CC2) is changed, the base station is adapted to: provide the changed system information to the first user equipment via a dedicated signaling on a dedicated channel of the first cell (CC1) as the first special cell, and provide the changed system information to the second user equipment via a dedicated signaling on a dedicated channel of the third cell (CC3) as the second special cell. communicate with a first user equipment , using at least two cells by carrier aggregation; provide, to the first user equipment , a first cell (CC1) among the at least two cells as a first special cell to keep connection between the base station and the first user equipment ; provide a second cell (CC2) among the at least two cells for use for the first user equipment as uplink and/or downlink resources: communicate with a second user equipment using the at least three cells by the carrier aggregation; provide, to the second user equipment , a third cell (CC3) among the at least three cells as a second special cell to keep connection between the base station and the second user equipment ; and provide the first cell (CC1) and the second cell (CC2) for use for the second user equipment as uplink and/or downlink resources, the second cell (CC2) and the third cell (CC3) being different from the first cell (CC1), wherein, when system information used for the second cell (CC2) is changed, the base station is adapted to: provide the changed system information to the first user equipment via a dedicated signaling on a dedicated channel of the first cell (CC1) as the first special cell, and provide the changed system information to the second user equipment via a dedicated signaling on a dedicated channel of the third cell (CC3) as the second special cell. provide the changed system information to the first user equipment via a dedicated signaling on a dedicated channel of the first cell (CC1) as the first special cell, and provide the changed system information to the second user equipment via a dedicated signaling on a dedicated channel of the third cell (CC3) as the second special cell. <EOS>