A base station comprises an RNC message receiver which receives data packets from a Radio Network Controller, RNC. The data packets are transmitted over air interface channels by a transmitter. Buffer memory buffers the data packets prior to transmission and a scheduler schedules the data packets for transmission over the air interface channels. A memory allocator determines a first memory allocation of the buffer memory for a first air interface communication with a first user equipment. A flow controller determining a transfer allowance for transferring of data from the RNC to the base station in response to the first memory allocation and a current buffer memory usage of the first air interface communication. The transfer allowance is transmitted to the RNC by an RNC message transmitter. The RNC only transmits data packets to the base station if the current transfer allowance is sufficient. Thereby an efficient flow control is achieved.