Problem: A packet error rate in a receiver needs to be effectively reduced.Solution to Problem: A transmitter 11 inserts error detection codes into information packets on one-to-one basis, at a certain layer at which signal processing is performed earlier than at a physical layer, to obtain first information packets. The transmitter 11 codes the first information packets at the physical layer to obtain second information packets, and transmits the second information packets. At the certain layer, the transmitter 11 generates parity packets by coding the information packets and inserts the error detection codes into the parity packets on one-to-one basis to obtain first parity packets. The transmitter codes the first parity packets at the physical layer to obtain second parity packets. The transmitter 11 transmits the second parity packets in accordance with a transmission request from each of one or more receivers.