RADIO COMMUNICATION CONTROL METHOD AND RADIO COMMUNICATION SYSTEM

摘要

BF weight vector determination is executed for each of M number of streams. In a first stage, by repeating switching of transmission BF weight (transmission beam) candidates in a small base station, a transmission BF weight vector with the best reception quality in a user apparatus UE is selected from among tried transmission BF weight vectors. In a second stage, by repeating switching of reception BF weight (reception beam) candidates in the user apparatus, a reception BF weight vector with the best reception quality in the user apparatus UE is selected from among tried reception BF weight vectors.

主权项

1. A radio communication control method in a radio communication system including a transmitter and a receiver,
the transmitter including:
a precoding unit that performs digital precoding on M (where M is an integer of 2 or more) number of streams using a precoding weight matrix;a transmission beamforming unit that performs, on a signal on which the digital precoding has been performed, analog transmission beamforming that imparts, to the signal, changes in phase and amplitude corresponding to a transmission BF (beamforming) weight matrix; andmultiple transmitting antennas that transmit the signal on which the analog transmission beamforming has been performed, the receiver including:
multiple receiving antennas that receive a signal that is transmitted from the transmitter and is propagated through space;a reception beamforming unit that performs, on the signal received by the multiple receiving antennas, analog reception beamforming that imparts, to the signal received by the multiple receiving antennas, changes in phase and amplitude corresponding to a reception BF weight matrix; anda postcoding unit that reproduces the M number of streams by performing, using a postcoding weight matrix, digital postcoding on the signal on which the analog reception beamforming has been performed, the radio communication control method comprising: for each of the M number of streams,
selecting a candidate transmission BF weight vector corresponding to the stream from multiple transmission BF weight vector candidates;transmitting, from the transmitter, a first reference signal on which analog transmission beamforming has been performed based on a candidate transmission BF weight matrix that includes the selected candidate transmission BF weight vector;estimating a first transmission/reception characteristic that represents a result of performing, on the first reference signal that is received by the receiver, analog reception beamforming based on a test reception BF weight matrix;determining a suitable transmission BF weight vector from the multiple transmission BF weight vector candidates based on multiple first transmission/reception characteristics acquired by executing the selecting, the transmitting, and the estimating for the multiple transmission BF weight vector candidates;selecting a candidate reception BF weight vector corresponding to the stream from multiple reception BF weight vector candidates;transmitting, from the transmitter, a second reference signal on which analog transmission beamforming has been performed based on a test transmission BF weight matrix that includes the determined suitable transmission BF weight vector;estimating a second transmission/reception characteristic that represents a result of performing, on the second reference signal received by the receiver, analog reception beamforming based on a candidate reception BF weight matrix that includes the selected candidate reception BF weight vector; anddetermining a suitable reception BF weight vector from the multiple reception BF weight vector candidates based on multiple second transmission/reception characteristics acquired by executing the selecting, the transmitting, and the estimating for the multiple reception BF weight vector candidates.