Terminal apparatus, feedback control method, base station, pairing control method, program, and wireless communication system

A feedback control method by a terminal apparatus provided with a wireless communication service from a base station as a serving base station on a channel to control feedback to the base station, the feedback control method comprising:

• estimating the channel to the base station by using a reference signal transmitted from the base station;
• selecting a transmission weight desirable for second down-link transmission from the base station to another terminal apparatus spatially multiplexed with first down-link transmission on the channel from a plurality of transmission weight candidates in accordance with an estimation result of the channel;
• and
• giving the feedback of the selected transmission weight to the base station,
• wherein when the first down-link transmission is not spatially multiplexed with another down-link transmission by the base station, the transmission weight desirable for the second down-link transmission is not fed back .

A non transitory computer readable medium storing a program for causing a computer controlling a terminal apparatus provided with a wireless communication service from a base station as a serving base station on a channel to function as:

• an estimation unit that estimates the channel to the base station by using a reference signal transmitted from the base station;
• a selection unit that selects a transmission weight desirable for second down-link transmission from the base station to another terminal apparatus spatially multiplexed with first down-link transmission on the channel from a plurality of transmission weight candidates in accordance with an estimation result by the estimation unit;
• and
• a feedback controller that controls feedback of the transmission weight selected by the selection unit to the base station,
• wherein when the first down-link transmission is not spatially multiplexed with another down-link transmission by the base station, the feedback controller does not feed back the transmission weight desirable for the second down-link transmission.

A base station providing a wireless communication service as a serving base station to a terminal apparatus on a channel, comprising:

• circuitry;
• and
• memory coupled to the circuity, the circuitry configured to:
• transmit a reference signal to the terminal apparatus;
• acquire feedback about a transmission weight selected by the terminal apparatus from a plurality of transmission weight candidates in accordance with an estimation result of the channel using the reference signal and desirable for second down-link transmission from the base station to another terminal apparatus spatially multiplexed with first down-link transmission on the channel;
• and
• control pairing for spatial multiplexing of the terminal apparatus and the another terminal apparatus by using the feedback acquired,
• wherein when the first down-link transmission is not spatially multiplexed with another down-link transmission, the circuitry is further configured to not acquire the feedback about the transmission weight desirable for the second down-link transmission.

A pairing control method by a base station providing a wireless communication service as a serving base station to a terminal apparatus on a channel to control pairing between terminal apparatuses based on feedback from the terminal apparatus, the pairing control method comprising:

• transmitting a reference signal to the terminal apparatus;
• acquiring feedback about a transmission weight selected by the terminal apparatus from a plurality of transmission weight candidates in accordance with an estimation result of the channel using the reference signal and desirable for second down-link transmission from the base station to another terminal apparatus spatially multiplexed with first down-link transmission on the channel;
• and
• determining pairing for spatial multiplexing of the terminal apparatus and the another terminal apparatus by using the acquired feedback,
• wherein when the first down-link transmission is not spatially multiplexed with another down-link transmission, the feedback about the transmission weight desirable for the second down-link transmission is not acquired.

A non transitory computer readable medium storing a program for causing a computer controlling a base station, providing a wireless communication service as a serving base station to a terminal apparatus on a channel, including a wireless communication unit that transmits a reference signal to the terminal apparatus to function as:

• a feedback acquisition unit that acquires feedback about a transmission weight selected by the terminal apparatus from a plurality of transmission weight candidates in accordance with an estimation result of the channel using the reference signal and desirable for second down-link transmission from the base station to another terminal apparatus spatially multiplexed with first down-link transmission on the channel;
• and
• a pairing controller that controls pairing for spatial multiplexing of the terminal apparatus and the another terminal apparatus by using the feedback acquired by the feedback acquisition unit,
• wherein when the first down-link transmission is not spatially multiplexed with another down-link transmission, the feedback acquisition unit does not acquire the feedback about the transmission weight desirable for the second down-link transmission.

A wireless communication system, comprising:

• a terminal apparatus;
• and
• a base station,
• wherein the terminal apparatus is provided with a wireless communication service from the base station as a serving base station on a channel,
• wherein the terminal apparatus includes circuitry configured to:
• estimate the channel to the base station by using a reference signal transmitted from the base station,
• select a transmission weight desirable for second down-link transmission from the base station to another terminal apparatus spatially multiplexed with first down-link transmission on the channel from a plurality of transmission weight candidates in accordance with an estimation result, and
• control feedback of the transmission weight selected to the base station,
• wherein the base station includes circuitry configured to:
• transmit the reference signal to the terminal apparatus,
• acquire feedback from the terminal apparatus, and
• control pairing for spatial multiplexing of the terminal apparatus and the another terminal apparatus by using the feedback acquired, and
• wherein when the first down-link transmission is not spatially multiplexed with another down-link transmission by the base station, the circuitry of the terminal apparatus is further configured to not feed back the transmission weight desirable for the second down-link transmission.