Patent ID: 8457229

Claim:
A radio communication apparatus comprising: a receiver configured to receive signals; a processor coupled to the receiver, configured to: obtain a reference amplitude that depends on a modulation scheme for a received signal received by the receiver, and on amplitude fluctuations of the received signal in a propagation path; perform demodulation of the received signal to obtain an in-phase component and a quadrature component of each received symbol included in the received signal; calculate a likelihood ratio for each of bits mapped to each received symbol using the reference amplitude and the in-phase or quadrature component, by at least one of: applying an operation expression including an absolute value operation to the reference amplitude and the in-phase or quadrature component of the received symbol, applying an operation expression including an absolute value operation to the reference amplitude and the in-phase or quadrature component of the received symbol, and applying a first-likelihood-ratio calculating to apply, to the reference amplitude and the in-phase component of the received symbol, an operation expression corresponding to the first bit mapped to the received symbol to calculate a likelihood ratio for the first bit, and a second-likelihood-ratio calculating to apply, to the reference amplitude and the quadrature component of the received symbol, the operation expression applied to the first-likelihood-ratio calculating to calculate a likelihood ratio for the second bit paired with the first bit; and perform error correction decoding on the received signal using the calculated likelihood ratios.