There is provided a method of controlling data transmission, a radio system, a base station and a controller. The base station is configured to determine a current allocated capacity for a priority queue by increasing the allocated capacity in the last control message when the amount of data in the buffer for the priority queue is less than the lower buffer threshold parameter. The base station also is configured to determine an allocated capacity for a priority queue by decreasing the allocated capacity used in a priority queue when the amount of data in the buffer for the priority queue is greater than the higher buffer threshold parameter. The base station also is configured to use the determined current allocated capacity as a parameter in a control message between the base station and the controller.