Communication system, relay apparatus, receiving apparatus, relay method, receiving method, relay program, and receiving program

摘要

A relay apparatus includes: an estimation unit selects a code book number corresponding to a reception SNR range based on an estimated reception SNR value; a soft demodulation unit that performs soft demodulation on a received first signal to detect a likelihood of the received first signal; a first memory unit that stores a first quantization code book showing, for each code book number, a relationship between a quantization parameter and a likelihood quantization bit value; a quantization unit that refers the first quantization code book to obtain a relationship between a quantization parameter and a likelihood quantization bit value that corresponds to the selected code book number, and adaptively quantizes the detected likelihood by using the obtained relationship to obtain a likelihood quantization bit value; and a transmission unit that transmits, to the receiving apparatus, a second signal including the obtained likelihood quantization bit value and the selected code book number.