Retransmission Method, Communication System, and Transmission Device

A retransmission method comprising:

• a generating step of, in a transmitting side, packetizing a channel coding codeword and generating a plurality of packets comprised of one or a plurality of encoded bits included in the channel coding codeword;
• an initial transmission step of, in the transmitting side, performing an initial transmission of the channel coding codeword;
• an initial decoding step of, in a receiving side, receiving and performing initial decoding of the channel coding codeword;
• a calculating step of, when a decoding error has occurred in the initial decoding step, deciding a reliability of each encoded bit included in the channel coding codeword and calculating the number of bits of low reliability;
• a position information feedback step of, in the receiving side, when the number of bits of low reliability is equal to or less than a first threshold, feeding back a negative acknowledgement signal and information about positions of the bits of low reliability;
• a packet number feedback step of, in the receiving side, when the number of bits of low reliability is greater than the first threshold, selecting one packet of the lowest reliability and feeding back a negative acknowledgement signal and a packet number of the selected one packet to the transmitting side;
• a bit retransmitting step of, in the transmitting side, when the negative acknowledgement signal and the information about the positions of the bits of low reliability are fed back from the receiving side, retransmitting the bits of low reliability based on the information about the positions of the bits of low reliability;
• and
• a packet retransmitting step of, in the transmitting side, when the negative acknowledgement signal and the packet number are fed back from the receiving side, retransmitting encoded bits included in a packet matching the packet number and a redundancy version.

A retransmission method comprising:

• a generating step of, in a transmitting side, packetizing a channel coding codeword and generating a plurality of packets comprised of one or a plurality of encoded bits included in the channel coding codeword;
• an initial transmission step of, in the transmitting side, performing an initial transmission of the channel coding codeword;
• an initial decoding step of, in a receiving side, receiving and performing initial decoding of the channel coding codeword;
• a calculating step of, when a decoding error has occurred in the initial decoding step, deciding a reliability of each encoded bit included in the channel coding codeword and calculating the number of bits of low reliability;
• a position information feedback step of, in the receiving side, when the number of bits of low reliability is equal to or less than a first threshold, feeding back a negative acknowledgement signal and information about positions of the bits of low reliability;
• a start signal feedback step of, in the receiving side, when the number of bits of low reliability is greater than a predetermined threshold, feeding back a negative acknowledgement signal and a start signal for a type II hybrid automatic retransmission request to the transmitting side;
• a bit retransmitting step of, in the transmitting side, when the negative acknowledgement signal and the information about the positions of the bits of low reliability are fed back from the receiving side, retransmitting the bits of low reliability based on the information about the positions of the bits of low reliability;
• and
• a redundancy version retransmitting step of, in the transmitting side, when the negative acknowledgement signal and the start signal for the type II hybrid automatic retransmission request are fed back from the receiving side, retransmitting a redundancy version.

A communication system comprising a transmitting apparatus and receiving apparatus, wherein:

• the transmitting apparatus comprises:
• a generating section that packetizes a channel coding codeword and generates a plurality of packets comprised of one or a plurality of encoded bits included in the channel coding codeword;
• an initial transmission section that performs an initial transmission of the channel coding codeword;
• and
• a packet retransmitting section that, when a packet number and negative acknowledgment signal are fed back from the receiving apparatus, retransmits encoded bits included in a packet matching the packet number and a redundancy version;
• and
• the receiving apparatus comprises:
• a decoding section that receives and decodes the channel coding codeword;
• an initial selection section that, when a decoding error has occurred in the decoding step, selects one packet of the lowest reliability amongst the plurality of packets;
• and
• a packet number feedback section that feeds back the negative acknowledgement signal and the packet number of the selected one packet to the transmitting apparatus.

A transmitting apparatus comprising:

• a generating section that packetizes a channel coding codeword and generates a plurality of packets comprised of one or a plurality of encoded bits included in the channel coding codeword;
• an initial transmission section that performs an initial transmission of the channel coding codeword;
• and
• a packet retransmitting section that, when a packet number and negative acknowledgment signal are fed back from a receiving apparatus, retransmits encoded bits included in a packet matching the packet number and a redundancy version.