Multi-input and multi-output communication method in large-scale antenna system
The present invention relates to a multi-input and multi-output communication method in a large-scale antenna system. An MIMO transmission method according to the present invention includes: obtaining statistical channel information on at least one terminal, dividing terminals into a plurality of classes and a plurality of groups based on the statistical channel information, wherein the groups depend on the classes; determining a group beam-forming matrix for each of the divided groups; performing a group beamforming transmission by group based on the group beam-forming matrix to obtain instantaneous channel information; and scheduling terminals based on the instantaneous channel information. Thus, it is possible to decrease the complexity in a scheduling and precoding calculation without an increase in the amount of wireless resources that are required for providing feedback for a reference signal and channel status information.
1. An operation method of a user equipment (UE) in a wireless communication system, the operation method comprising:
receiving, from a base station, information on a number of antennas and a subset of beams which is selected among all possible beams of the base station;
generating a codebook based on the number of antennas included in the information;
receiving a reference signal (RS) from the base station;
determining channel state information (CSI) based on the RS and the subset of beams by using the codebook; and
reporting the CSI to the base station,
wherein the codebook is generated by using Kronecker product of a first beamforming vector and a second beamforming vector which are associated with different directions.
2. The operation method of claim 1 ,
wherein the codebook is generated based on following equation:
W
g
,
l
(
t
)
∈
{
[
b
H
,
g
,
i
(
t
)
⊗
b
V
,
g
,
h
(
t
)
α
b
g
,
i
(
t
)
⊗
b
V
,
g
,
h
(
t
)
]
:
i
=
1
,
⋯
,
b
H
′
,
h
=
1
,
⋯
,
b
V
′
and
α
=
1
,
-
1
,
j
,
-
j
}
,
wherein:
b H,g,j (t) is the first beamforming vector,
b V,g,h (t) is the second beamforming vector,
α is a co-phasing factor,
i is an index of the first beamforming vector,
h is an index of the second beamforming vector,
b′ H is the number of first beamforming vectors,
b′ V is the number of second beamforming vectors, and
wherein each of the b′ H and the b′ V is determined based on the information on the number of antennas and the subset of beams.
3. The operation method of claim 1 , wherein the CSI includes at least one of a precoding matrix indicator (PMI), a channel quality indicator (CQI), and a rank indicator (RI).