Data transmission with a wireless communication device which communicates over an air interface with a radio network is controlled by setting a radio link control (RLC) window size for a first logical connection established with the wireless communication device over the air interface, the RLC window size indicating a number of RLC protocol data units (PDUs), periodically estimating a total amount of memory available at the wireless communication device for storing RLC PDUs, and controlling transmission of RLC PDUs associated with the first logical connection to the wireless communication device based on the estimated total amount of memory available at the wireless communication device for storing RLC PDUs, or based on the RLC window size set for the first logical connection if the RLC window size limits the transmission of the RLC PDUs more than the estimated total amount of memory available at the wireless communication device.