The present invention relates to a method and arrangements for controlling transmission of data bits in a bit transfer session for transmitting data information from an application server (2) to a client (1), said bit transfer session involving bit transfer over a wireless communications link by means of a transport protocol with a flow control mechanism. According to the present invention a radio resource managing unit (6) sends information regarding the bandwidth on the wireless link that the bit transfer session currently is allowed to use. This feedback information from the radio resource managing unit is used to set and update flow control parameters continuously throughout the session. Thereby optimization of the flow control parameters is facilitated, which makes it possible to enhance the end-user QoS and provide more efficient use of available radio resources.