Radio transmission apparatus and radio transmission method
View Patent ↗Data streams stored in buffers are modulated by modulation sections. Multipliers multiply the signals output from the modulation sections by weights output from a weight control section. The signals output from the multipliers are added up by addition sections, subjected to radio transmission processing by transmission radio sections and sent through antennas. A buffer control section controls the buffers based on a retransmission count output from a retransmission count detection section. The weight control section outputs weights different from weights at the time of previous transmission to the multipliers every time data is retransmitted. This allows a diversity gain at the time of data retransmission to be increased even if a time variation of the propagation path environment for radio signals is slow.
1. A transmission apparatus comprising:
a multiplier which, in operation, multiplies a plurality of streams by a plurality of weights;
a transmitter which, in operation, transmits the plurality of streams multiplied with the plurality of weights using a plurality of antennas;
a receiver which, in operation, receives feedback information including acknowledgment/negative acknowledgment (ACK/NACK) information and channel quality information (CQI) which are transmitted from a reception apparatus; and
a weight controller which, in operation, selects a plurality of weights for a re-transmission, in case the NACK information is received, wherein the plurality of weights to be multiplied with the plurality of streams, respectively, are rearranged between an initial transmission and the re-transmission based on the received CQI,
wherein correspondence relationships between the plurality of streams and the plurality of weights for the re-transmission are derived from the feedback information for the initial transmission.
2. The transmission apparatus according to claim 1 , wherein
the plurality of weights are rearranged such that, in an even-numbered transmission, weights used in an odd-numbered transmission are used as weights for different streams in the even-numbered transmission from streams used in the odd-numbered transmission.
3. The transmission apparatus according to claim 1 , wherein
in an even-numbered transmission, the transmitter re-transmits the same data as data of an odd-numbered transmission.
4. The transmission apparatus according to claim 1 , wherein
a first weight multiplied with a first stream in an even-numbered transmission is the same as a second weight multiplied with a second stream in an odd-numbered transmission.
5. The transmission apparatus according to claim 1 , wherein
the plurality of weights used in an even-numbered transmission are selected from among the plurality of weights used in an odd-numbered transmission.
6. A transmission method comprising:
multiplying a plurality of streams by a plurality of weights;
transmitting the plurality of streams multiplied with the plurality of weights using a plurality of antennas;
receiving feedback information including acknowledgment/negative acknowledgment (ACK/NACK) information and channel quality information (CQI) which are transmitted from a reception apparatus; and
selecting a plurality of weights for a re-transmission, in case the NACK information is received, wherein the plurality of weights to be multiplied with the plurality of streams, respectively, are rearranged between an initial transmission and the re-transmission based on the received CQI,
wherein correspondence relationships between the plurality of streams and the plurality of weights for the re-transmission are derived from the feedback information for the initial transmission.
7. The transmission method according to claim 6 , wherein
the plurality of weights are rearranged such that, in an even-numbered transmission, weights used in an odd-numbered transmission are used as weights for different streams in the even-numbered transmission from streams used in the odd-numbered transmission.
8. The transmission method according to claim 6 , wherein
in an even-numbered transmission, the transmitting includes re-transmitting the same data as data of an odd-numbered transmission.
9. The transmission method according to claim 6 , wherein
a first weight multiplied with a first stream in an even-numbered transmission is the same as a second weight multiplied with a second stream in an odd-numbered transmission.
10. The transmission method according to claim 6 , wherein
the plurality of weights used in an even-numbered transmission are selected from among the plurality of weights used in an odd-numbered transmission.