A mobile communication system using an enhanced uplink dedicated transport channel transmits data at a relatively low effective data rate through autonomous transmission. Data transmission time points for user equipments (UEs) have different values in the autonomous transmission and therefore uplink interference is reduced. An autonomous transmission period N and the number of autonomous transmissions k are determined such that each UE performs the autonomous transmission. A Node B and each UE are notified of possible autonomous transmission time points based on the determined autonomous transmission period N and the determined number of autonomous transmissions k through signaling. The UE transmits the uplink data without the Node B's scheduling at the possible autonomous transmission time points.