A base station receiving uplink data transmitted from mobile terminals of first type and mobile terminals of second type over a radio interface using plural sub-carriers. The mobile terminals of first type transmit uplink data on a first group of the sub-carriers over a first bandwidth and the mobile terminals of second type transmit uplink data on a second group of the sub-carriers within the first group of sub-carriers over a second bandwidth that is smaller than the first bandwidth. The base station is configured to grant uplink radio resources in response to random access request messages transmitted by mobile terminals of first type transmitted on a first random access channel and to grant uplink radio resources in response to random access request messages transmitted by mobile terminals of second type transmitted on a second random access channel, which are transmitted on sub-carriers within the second group of sub-carriers.