Ntt Docomo, Inc.

Karim Ibrahim Khashaba

Hidekazu Taoka

Katsutoshi Kusume

Guido Dietl

To perform feedback of channel information suitable for MU-MIMO transmission while exploiting a codebook that defines precoding matrixes and PMIs suitable for SU-MIMO transmission, it is a feature that a channel matrix corresponding to a channel transmission path is defined using a plurality of precoding matrixes defined in a codebook suitable for SU-MIMO transmission and a plurality of adjustment coefficients to respectively adjust the plurality of precoding matrixes, a channel information selecting section () selects a plurality of precoding matrixes and/or a plurality of adjustment coefficients, and that the selected plurality of precoding matrixes and/or the plurality of adjustment coefficients are transmitted to a base station apparatus as channel information in uplink.

Mobile station apparatus and channel information feedback method

A data transmission method includes, in the mobile station apparatus, selecting a PMI and an RI corresponding to an Hermitian transpose of a channel matrix indicative of channel characteristics and calculating a CQI from the PMI. The method further includes transmitting the PMI, the RI, and the CQI to the base station apparatus as feedback information. The method further includes, in the base station apparatus, calculating a first data rate of a case of performing SU-MIMO transmission based on the PMI transmitted from the mobile station apparatus as feedback and calculating a second data rate of a case of performing ZF MU-MIMO transmission based on the PMI. The method further includes selecting a transmission scheme corresponding to a higher data rate between the first and second data rates.

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Tokyo, Japan

Karim Ibrahim Khashaba