In a quadrature amplitude modulation (QAM) communication system and corresponding method, and a QAM receiving apparatus and corresponding method, a sending apparatus that generates a sending signal adds CRC bits thereto. In a receiving apparatus, data rate is determined without a 16QAM demapping circuit and/or notification of the data rate, by 64QAM demapping a symbol string based on the received signal using a demapping circuit, independently of whether 16QAM or 64QAM was used on the sent signal. A bit string is thus obtained, and by thinning the bit string responsive to a CRC detection result of a CRC detection circuit, an output signal is provided using a thinning circuit.