Receiver query for a data transfer with sliding window data flow control

摘要

A method for controlling the transmission of signals in a communications system uses a polling trigger which prevents a deadlock condition from occurring between a transmitter and receiver. The method includes selecting a protocol data unit from a buffer, determining whether the data unit is located at a predetermined position within a transmission window, and then transmitting polling information with the data unit if the data unit is determined to be at the predetermined position of the transmission window. The predetermined position is preferably a last position of the window. If the data unit is not in a last position of the transmission window, additional steps of the method include determining whether the data unit is a last-stored data unit in a transmission buffer. If so, polling information is transmitted with the data unit. If neither polling trigger is satisfied, the data unit is transmitted without polling information. The method may at least partially be performed within a radio link control layer of the transmitter operating in acknowledged mode. A user terminal or network apparatus may include a computer program for performing the steps of the method. By controlling the transmission of polling information based on the aforementioned triggers, a deadlock condition is advantageously prevented. As a result, the efficiency and the reliability of communications is substantially improved. IMAGE