US Patent 7444578 Data unit sender and method of controlling the same

A data unit sender and method of controlling a data unit sender are presented, in which a time-out monitoring procedure implements a first, longer time-out period (SRTO), and a second, shorter time-out period (QRTO), where a retransmission is executed after the shorter time-out period if the available transmission capacity value for unsent data is greater or equal to the size of a designated data unit that is to be retransmitted as a result of time-out monitoring procedure.