Method and apparatus for transmitting uplink signals using multi-antenna
A method and apparatus for allowing a UE to transmit uplink signals using a MIMO scheme are disclosed. In order to maintain good Peak power to Average Power Ratio (PAPR) or Cubic Metric (CM) properties when the UE transmits uplink signals using the MIMO scheme, the UE uses a precoding scheme based on a precoding matrix established in a manner that one layer is transmitted to each antenna in specific rank transmission.
1. A method for a user equipment (UE) to transmit uplink signals, the method comprising:
precoding signals of 2 layers by using a specific precoding matrix P multiplied by a predetermined constant value, wherein the specific precoding matrix P is selected from a Rank 2 codebook consisting of a first type of
[
1
0
X
0
0
1
0
Y
]
,
a second type of
[
1
0
0
1
X
0
0
Y
]
,
and a third type of
[
1
0
0
1
0
Y
X
0
]
,
wherein ‘X’ and ‘Y’ are selected from among {1, j, −1, −j}; and
transmitting the precoded signals to a base station via 4 transmission antennas.
2. The method of claim 1 , wherein the specific precoding matrix P multiplied by the predetermined constant value is represented as P′,
P
′
∈
{
k
·
[
1
0
X
0
0
1
0
Y
]
,
k
·
[
1
0
0
1
X
0
0
Y
]
,
k
·
[
1
0
0
1
0
Y
X
0
]
}
,
wherein ‘k’ represents the predetermined constant value.
3. The method of claim 1 , wherein a number of precoding matrixes of the Rank 2 codebook is 16.
4. A user equipment (UE) for transmitting uplink signals, the UE comprising:
multiple transmission antennas for transmitting uplink signals;
a memory for storing codebooks of all ranks; and
a processor connected to the multiple transmission antennas and the memory so as to process transmission of the uplink signals,
wherein a Rank 2 codebook among the codebooks stored in the memory consists of a first type of
[
1
0
X
0
0
1
0
Y
]
,
a second type of
[
1
0
0
1
X
0
0
Y
]
,
and a third type of
[
1
0
0
1
0
Y
X
0
]
wherein ‘X’ and ‘Y’ are selected from among {1, j, −1, −j}.
5. The UE of claim 4 , wherein the processor is configured to use the precoding matrix P multiplied by a predetermined constant value for precoding the signals.
6. The UE of claim 4 , wherein a number of precoding matrixes of the Rank 2 codebook is 16.