A communication system comprising: a communication station that transmits data; and first and second communication terminals (2-1, 2-2) each of which receives the data from the communication station and is capable of sending the communication station a request for retransmitting data, wherein: the communication station comprises a synthesizer that, if the communication station receives a request for retransmitting first data from the first communication terminal, creates synthesized data through vector synthesis on the first data destined for the first communication terminal and on second data destined for the second communication terminal, and a transmitter that transmits the synthesized data created by the synthesizer using a single communication resource; and the second communication terminal comprises a memory that stores the first data for which the request for retransmission is sent, and a decoder that receives the synthesized data from the communication station and retrieves the second data based on the synthesized data and the first data stored in the memory. a communication station that transmits data; and first and second communication terminals (2-1, 2-2) each of which receives the data from the communication station and is capable of sending the communication station a request for retransmitting data, wherein: the communication station comprises a synthesizer that, if the communication station receives a request for retransmitting first data from the first communication terminal, creates synthesized data through vector synthesis on the first data destined for the first communication terminal and on second data destined for the second communication terminal, and a transmitter that transmits the synthesized data created by the synthesizer using a single communication resource; and the second communication terminal comprises a memory that stores the first data for which the request for retransmission is sent, and a decoder that receives the synthesized data from the communication station and retrieves the second data based on the synthesized data and the first data stored in the memory. the communication station comprises a synthesizer that, if the communication station receives a request for retransmitting first data from the first communication terminal, creates synthesized data through vector synthesis on the first data destined for the first communication terminal and on second data destined for the second communication terminal, and a transmitter that transmits the synthesized data created by the synthesizer using a single communication resource; and a synthesizer that, if the communication station receives a request for retransmitting first data from the first communication terminal, creates synthesized data through vector synthesis on the first data destined for the first communication terminal and on second data destined for the second communication terminal, and a transmitter that transmits the synthesized data created by the synthesizer using a single communication resource; and the second communication terminal comprises a memory that stores the first data for which the request for retransmission is sent, and a decoder that receives the synthesized data from the communication station and retrieves the second data based on the synthesized data and the first data stored in the memory. a memory that stores the first data for which the request for retransmission is sent, and a decoder that receives the synthesized data from the communication station and retrieves the second data based on the synthesized data and the first data stored in the memory.