The present invention relates to a network node and a method in a radio communications network for providing a radio interface between the radio base station and a mobile terminal, provided to assign transmission rates to the mobile terminal to be used in an uplink packet data channel from the mobile terminal to the radio base station. A receiver is provided to receive at least a first rate request from the mobile terminal requesting increased transmission rate, a measurement device is provided to measure the utilised transmission rate for the packet data transmission from the mobile terminal to the radio base station, and a message transmitter is provided to send a new grant message to the mobile terminal repeating the first transmission rate, if the measured transmission rate is lower than a first specified fraction of the assigned first transmission rate.