Radio base station, user terminal, radio communication system and radio communication method

A radio base station that transmits and receives signals with a user terminal that establishes wireless connection, the radio base station comprising:

• an array antenna that has a plurality of antenna elements aligned in one direction, the plurality of antenna elements being divided into a plurality of groups in the direction of the alignment of the elements;
• a precoding multiplication section configured to multiply signals to supply to the antenna elements, by each weight of precoding weights, per group;
• a precoding weight section configured to generate precoding weights by which the array antenna forms at least a first beam that is directed to a cell edge side and a second beam that is directed to a cell center side in parallel;
• and
• a mapping section configured to arrange different reference signals allocated respectively to the first beam and the second beam, in separate resources.

A user terminal that establishes wireless connection with a radio base station, the user terminal comprising:

• a receiving section configured to receive a first beam that is directed to a cell edge side and a second beam that is directed to a cell center side, formed by the radio base station in parallel;
• a channel quality measurement section configured to extract reference signals from each of the received first beam and second beam and measure channel quality;
• a feedback signal generating section configured to generate a communication quality feedback signal that includes the channel quality measured from at least one of the first and second beams;
• and
• a transmission section configured to feed back the generated communication quality feedback signal to the radio base station via an uplink.

A radio communication method for transmitting and receiving signals between a radio base station that forms a cell and a user terminal that establishes wireless connection with the radio base station, wherein:

• the radio base station comprises an array antenna that has a plurality of antenna elements aligned in one direction, the plurality of antenna elements being divided into a plurality of groups in the direction of the alignment of the elements;
• the radio base station:
• multiplies signals to supply to the antenna elements, by each weight of precoding weights, per group;
• generates precoding weights by which the array antenna forms at least a first beam that is directed to a cell edge side and a second beam that is directed to a cell center side in parallel;
• and
• arranges different reference signals allocated respectively to the first beam and the second beam, in separate resources;
• the user terminal:
• receives the first beam and the second beam;
• extracts the reference signals from each of the received first beam and second beam and measures channel quality;
• generates a communication quality feedback signal that includes the channel quality measured from at least one of the first and second beams;
• and
• feeds back the generated communication quality feedback signal to the radio base station via an uplink.