Patent ID: 9281926
Filing Date: 2016-03-08
CPC Classification: H04L

Claim Text:
1. A radio base station apparatus comprising: a plurality of transmission antennas; a downlink reference signal generating section configured to generate first reference signals that are Common Reference Signals (CRSs) arranged in respective subframes, each of the subframes being a transmission time unit, second reference signals that are Channel State Information (CSI) measurement reference signals associated with respective antenna ports and used in measurement of channel quality, and third reference signals that are DeModulation Reference Signals (DM-RSs) associated with respective layers and used in demodulation of downlink transmission data; and a transmission section configured to arrange the first reference signals and the third reference signals in the subframes to transmit from the respective transmission antennas and configured to arrange the second reference signals in specific subframes to transmit from the respective transmission antennas, wherein the transmission section arranges, in some timing, the first reference signals in one subframe at a first density, and arranges, in other timing corresponding to a Multimedia Broadcast Multicast Service Single Frequency Network (MBSFN) subframe, the first reference signals in one subframe at a second density that is lower than the first density, and the transmission section signals, to a mobile station apparatus, subframe information to identify the MBSFN subframe in which the first reference signals are arranged at the second density.