one of the one way iub tn delay times t2 u2212 t1 and t4 u2212 t3 preferably the longer of the times t2 u2212 t1 and t4 u2212 t3 is used to be conservative in this embodiment the rlc transmission size is set such that an amount of data corresponding to the rlc transmission window size is substantially equal to an amount of data that can be transferred within twice the actual uplink or the downlink delay times which ever is greater referring back to fig4 when updating the rlc transmission window size there can be factors other than the data rate and delays on the iub tn fig8 illustrates an example process to perform the step s 430 in consideration of these other factors in step s 810 an appropriate rlc transmission window size is determined based on the data rate note that any one or more of the formulas 1 2 3 and 4 may be used for this purpose in step s 820 the rnc determines whether there is congestion in the iub tn in one embodiment the hs dsch ca frame received from the node b is used for this purpose the ca frame can include a two bit congestion status parameter according to the existing 3gpp standard indicating whether or not there a congestion condition exists in the downlink direction from the rnc to the node b for the flow there are two types u2014 u201c loss u201d or u201c delay u201d loss indicates that actual data.