A scheduler provided according to an aspect of the present invention provides higher priority for data units in a low priority queue upon occurrence of a starvation condition, and to packets in a high priority queue otherwise. The scheduler permits retransmission of a data unit in the lower priority queue when in the starvation condition, but clears the starvation condition when the data unit is retransmitted a pre-specified number of times. As a result, the data units in the higher priority queue would continue to be processed, thereby avoiding a deadlock at least in certain situations.