MIMO transmission device and MIMO transmission method
Provided are a MIMO transmission device and a MIMO transmission method which can improve reception quality of a response signal. A terminal ( 100 ) as the MIMO transmission device maps a first and a second element of the ACK/NACK signal vector formed from ACK/NACK signals onto a first and a second stream, respectively, and transmits the elements contained in a 2SC-FDMA symbol in a single slot. In the terminal ( 100 ), a response signal vector formation unit ( 140 ) forms [aSack, O] as the ACK/NACK signal vector in a first SC-FDMA symbol and [O, aSack] as an ACK/NACK signal vector in a second SC-FDMA symbol. A precoding unit ( 165 ) uses a unitary matrix to precode the ACK/NACK signal vector formed in the response signal vector formation unit ( 140 ).
1. A transmission apparatus comprising:
a vector forming section configured to form a plurality of ACK/NACK signal vectors based on a signal indicative of ACK/NACK, the plurality of ACK/NACK signal vectors including a first ACK/NACK signal vector and a second ACK/NACK signal vector different from the first ACK/NACK signal vector;
a signal generator configured to generate a first stream using a first sequence, the first ACK/NACK signal vector and the second ACK/NACK signal vector, and to generate a second stream using a second sequence different from the first sequence, the first ACK/NACK signal vector and the second ACK/NACK signal vector; and
a transmission section configured to transmit the first stream and the second stream that are spatial-multiplexed.
2. The transmission apparatus according to claim 1 , wherein a combination of elements included in the first ACK/NACK signal vector is different from a combination of elements included in the second ACK/NACK signal vector.
3. The transmission apparatus according to claim 1 , wherein a phase of the first ACK/NACK signal vector is different from a phase of the second ACK/NACK signal vector.
4. The transmission apparatus according to claim 1 , wherein each of the first ACK/NACK signal vector and the second ACK/NACK signal vector includes an element which is the same as said signal indicative of ACK/NACK and another element which is different from said signal indicative of ACK/NACK.
5. The transmission apparatus according to claim 4 , wherein the other element is generated from said signal indicative of ACK/NACK.
6. The transmission apparatus according to claim 1 , wherein the first ACK/NACK signal vector includes a first element and a second element, which are both the same as said signal indicative of ACK/NACK, and the second ACK/NACK signal vector includes a first element which is the same as said signal indicative of ACK/NACK and a second element which is generated from said signal indicative of ACK/NACK.
7. The transmission apparatus according to claim 1 , wherein each of the first ACK/NACK signal vector and the second ACK/NACK signal vector includes a first element which is generated from said signal indicative of ACK/NACK and a second element which is not generated from said signal indicative of ACK/NACK.
8. The transmission apparatus according to claim 1 , wherein the first ACK/NACK signal vector is mapped on a first symbol and the second ACK/NACK signal vector is mapped on a second symbol, the first and second symbols being included in one subframe.
9. The transmission apparatus according to claim 8 , wherein, in said one subframe, the first symbol is a symbol immediately before a reference signal and the second symbol is a symbol immediately after the reference signal.
10. The transmission apparatus according to claim 1 , wherein the first ACK/NACK signal vector and the second ACK/NACK signal vector are respectively mapped repeatedly on corresponding symbols in one subframe.
11. The transmission apparatus according to claim 1 , wherein the first ACK/NACK signal vector and the second ACK/NACK signal vector are respectively replicated, and the replicated ACK/NACK signal vectors are transmitted on the first stream and the second stream by being spatial-multiplexed.
12. The transmission apparatus according to claim 1 , wherein the first stream and the second stream do not include an element that is zero.
13. The transmission apparatus according to claim 1 , wherein the first ACK/NACK signal vector is orthogonal to the second ACK/NACK signal vector.
14. The transmission apparatus according to claim 1 , wherein the first ACK/NACK signal vector and the second ACK/NACK signal vector are mapped around a reference signal on each slot in one subframe.
15. The transmission apparatus according to claim 1 , wherein the first ACK/NACK signal vector and the second ACK/NACK signal vector are mapped by overwriting data.
16. A transmission method comprising:
forming a plurality of ACK/NACK signal vectors based on a signal indicative of ACK/NACK, the plurality of ACK/NACK signal vectors including a first ACK/NACK signal vector and a second ACK/NACK signal vector different from the first ACK/NACK signal vector;
generating a first stream using a first sequence, the first ACK/NACK signal vector and the second ACK/NACK signal vector, and generating a second stream using a second sequence different from the first sequence, the first ACK/NACK signal vector and the second ACK/NACK signal vector; and
transmitting the first stream and the second stream that are spatial-multiplexed.