Patent ID: 8824585

Claim:
A communication apparatus calculating a CQI (Channel Quality Indicator) indicating reception quality of a reception signal and feeding back the CQI to another communication apparatus, the CQI containing information obtained by averaging SNRs (Signal to Noise power Ratios) of a plurality of subbands, which are generated by dividing a reception band into a predetermined number in the reception band, the communication apparatus comprising: a calculation unit which calculates an average SNR by using a predetermined approximation method; and a feedback unit which transmits a feedback information of the CQI based on the calculation result obtained by the calculation unit to the another communication apparatus, wherein the predetermined approximation method is based on a Newton's method, and wherein the calculation unit calculates an initial value p 0 (L) as p 0 (L)=10 SNRest — ave(L)/10 by using SNR est — ave (L)=(1/(KN f ))Σ K Σ f (10 log 10 SINR(P^ w , L, f, K)), where P^ w denotes a PMI (Precoding Matrix Indicator) common in an entire band indicating that a communication capacity is maximum, L denotes a layer number, f denotes a subcarrier number where a RS (Reference Signal) on a frequency axis is mapped, K denotes a subband number, N f denotes a number of subcarriers, SINR(P^ w , L, f, K) denotes an effective SNR, and SNR est — ave (L) denotes an average SNR.