Method of generating transmission control parameters and method of selective retransmission according to packet characteristics

A selective retransmission method for transmitting data of an MPEG-2 frame, comprising:

• (a) allowing a transmitting side medium access control (MAC) layer to transmit packets belonging to an I-frame to a receiving side MAC layer;
• (b) after all packets belonging to the I-frame are transmitted, allowing the receiving side MAC layer to output to the transmitting side MAC layer a retransmission request for non-received packets due to any transmission error generated during transmission of the packets;
• (c) allowing the transmitting side MAC layer, which received the retransmission request, to discard a number of packets of a B-frame following the I-frame, wherein the number of discarded packets of the B-frame equals a number of packets subject to the retransmission request;
• and
• (d) retransmitting the packets subject to the retransmission request.

A selective retransmission method, by which a transmitting side medium access control (MAC) layer transmits packets of an MPEG-2 frame, comprising:

• (a) determining whether a packet, to be currently transmitted by the transmitting side MAC layer, belongs to an I-frame;
• (b) if the packet does not belong to the I-frame, transmitting the packet as is, and if the packet belongs to the I-frame, determining whether the packet is a start packet of the I-frame;
• (c) if the packet is the start packet of the I-frame, transmitting to a receiving side MAC layer an automatic retransmission start message including the number of packets belonging to the I-frame;
• and
• (d) preparing a buffer for use in an automatic retransmission request (ARQ) mode and transmitting the packets with their respective sequence numbers.

A selective retransmission method, by which a transmitting side medium access control (MAC) layer transmits packets of an MPEG-2 frame, comprising:

• (a) starting an automatic retransmission request (ARQ) mode, and receiving a retransmission message of an MPEG-2 frame and sequence numbers of packets requiring retransmission, from a receiving side MAC layer;
• (b) receiving the retransmission message and the sequence numbers, determining whether any packets require retransmission, and if any packet requires retransmission, discarding a number of packets of a B-frame during a transmission standby state, wherein the number of discarded packets of the B-frame equals a total number of packets requiring retransmission;
• and
• (c) determining whether the number of the packets of the B-frame is less than the total number of packets requiring retransmission, and if the number of packets of the B-frame is not less than the total number of packets requiring retransmission, then retransmitting the packets and awaiting a next retransmission message.

A selective retransmission apparatus, in which a receiving side medium access control (MAC) layer receives packets of an MPEG-2 frame from a transmitting side MAC layer, comprising:

• a frame detector adapted to detect whether a frame type of the packet is an I-frame;
• a transmission error detector adapted to detect any non-received I-frame packets due to any transmission error generated during transmission of the I-frame packets;
• and
• a retransmission function unit adapted to output to the transmitting side MAC layer a retransmission message and sequence number information of the non-received I-frame packets if any transmission error exists, and to receive the non-received I-frame packets through retransmission by the transmitting side MAC layer in place of an equal number of subsequent non I-frame packets of a subsequent MPEG-2 frame.