Patent ID: 6684354
Filing Date: 2004-01-27
Classification: H04L

Abstract:
A data transmission method in which data transmission from the transmitting end to the receiving end is continuously performed in units of packets, each packet having additional information relating to its sequence number, priority, and data reproduction time at the receiving end, while successively reproducing data of packets which have arrived at the receiving end and, at this time, only packets which can be in time for data reproduction at the receiving end are retransmitted, said method comprising the steps of:at the transmitting end, giving a data reproduction time at the receiving end to each packet to be transmitted; and storing, as retransmission data, only data of packets the priorities of which are equal to or higher than a predetermined value, in a retransmission buffer; at the receiving end, when a transmission error is detected, detecting the reproduction time for an error packet and the arrival time of the error packet, and deciding an arrival time limit in accordance with the reproduction time; and when the error packet has arrived before the arrival time limit, outputting a retransmission request for the error packet to the transmitting end by indicating the sequence number of this error packet; at the transmitting end, when the data of the packet having the sequence number indicated by the retransmission request from the receiving end is stored in the retransmission buffer, retransmitting data of the packet the transmission time of which does not pass the reproduction time, to the receiving end, while discarding data of the packet the transmission time of which has passed the reproduction time; and discarding the data stored in the retransmission buffer in order starting from a packet which cannot be in time for data reproduction at the receiving end, wherein: at the transmitting end, additional information relating to the sequence number and the reproduction time corresponding to a target packet to be transmitted is embedded in a subsequent packet to be transmitted after the target packet; and at the receiving end, when a transmission error of the target packet has occurred and the additional information of the target packet has an error, a retransmission request for the target packet as an error packet is made on the basis of the additional information of the target packet which is embedded in the subsequent packet, when the subsequent packet transmitted after the target packet is received.