Codebook design for beamformed CSI-RS for FD-MIMO
Codebook designs are disclosed for full-dimensional multiple-input-multiple output (FD-MIMO) wireless cellular systems. The FD-MIMO cookbooks employ channel state information reference signals (CSI-RS). The codebook designs are used in beamforming CSI-RSs by the enhanced nodeB (eNB), where the CSI-RS is sent to the user equipment (UE), enabling the UE to perform channel estimation. The codebooks support beam selection, co-phasing between polarizations, and beam combining.
1. A user equipment (UE) to perform channel estimation of a transmission channel of a wireless cellular network, the UE is configured to:
measure a channel state information reference signal (CSI-RS) of a downlink signal received on the transmission channel;
calculate channel state information (CSI) of the transmission channel using a codebook along with the CSI-RS, the codebook comprising a plurality of precoding matrices, the codebook further comprising non-constant modulus elements with at least two non-zero elements in a precoding vector among a plurality of vectors of the codebook; and
report the CSI of the transmission channel by way of an uplink transmission.
2. The UE of claim 1 , the UE to further:
calculate the CSI of the transmission channel using a precoding matrix of the codebook, wherein each vector of the precoding matrix comprises a concatenation at least two selection vectors and each selection vector comprises a single non-zero element and remaining zero elements.
3. The UE of claim 2 , the UE to further:
calculate the CSI of the transmission channel using the precoding matrix of the codebook, wherein the single non-zero element in the selection vector has a first amplitude and a first phase and a second non-zero element has the first amplitude and a second phase, wherein the first phase differs from the second phase by 0, π/2, 2π/2, or 3π/2.
4. The UE of claim 1 , the UE to further:
calculate the CSI of the transmission channel using a precoding matrix of the codebook, wherein each vector of the precoding matrix comprises a concatenation of at least two selection vectors and each selection vector comprises a first non-zero element, a second non-zero element, and remaining zero elements.
5. The UE of claim 4 , wherein the first and second non-zero element in a first selection vector has a first amplitude and the first and second non-zero element in a second selection vector has a second amplitude and a second phase, wherein a first phase differs from the second phase by 0, π/2, π, or 3π/4.
6. The UE of claim 4 , wherein the first non-zero element in the selection vector has a first amplitude and a first phase and the second non-zero element has the first amplitude and a second phase, wherein the first phase differs from the second phase by 0 or π.
7. The UE of claim 1 , the UE to further:
calculate the CSI of the transmission channel using the codebook, wherein each of the plurality of matrices in the codebook comprises vectors in which each vector comprises four non-zero elements and remaining zero elements.
8. The UE of claim 4 , wherein the first non-zero element has a first amplitude and a first phase and the second non-zero element has the first amplitude and a second phase, wherein the first phase differs from the second phase by 0, π/2, π, or 3π/2.
9. The UE of claim 1 , the UE to further:
calculate the CSI of the transmission channel using the codebook, wherein the codebook for rank 1 CSI reporting contains at least one element from the following set of the vectors:
1
2
[
e
m
e
j
α
e
m
]
,
1
2
[
e
m
-
e
j
α
e
m
]
,
{
m
}
=
0
,
…
,
N
p
/
2
-
1
,
{
α
}
=
0
,
π
/
2
,
wherein e m is a selection vector of length N p /2, N p is a total number of CSI-RS antenna ports.
10. The UE of claim 1 , the UE to further:
calculate the CSI of the transmission channel using the codebook, wherein the codebook for rank 2 CSI reporting contains at least one element from the following set:
1
4
[
e
m
e
m
e
j
α
e
m
-
e
j
α
e
m
]
,
{
m
}
=
0
,
…
,
N
p
/
2
-
1
,
{
α
}
=
0
,
π
/
2
,
wherein e m is a selection vector of length N p /2, N p is a total number of CSI-RS antenna ports.
11. The UE of claim 1 , the UE to further:
calculate the CSI of the transmission channel using the codebook, wherein the codebook for rank 3 CSI reporting contains at least one element from the following set:
1
16
[
e
m
e
m
e
k
e
j
α
e
m
-
e
j
α
e
m
e
j
β
e
k
]
,
1
16
[
e
m
e
k
e
k
e
j
α
e
m
e
j
β
e
k
-
e
j
β
e
k
]
,
{
m
,
k
}
=
0
,
…
,
N
p
/
2
-
1
,
m
≠
k
,
{
α
,
β
}
=
0
,
π
/
2
wherein e m is a selection vector of length N p /2, N p is a total number of CSI-RS antenna ports.
12. The UE of claim 1 , the UE to further:
calculate the CSI of the transmission channel using the codebook, wherein the codebook for rank 4 CSI reporting contains at least one element from the following set:
1
8
[
e
m
e
m
e
k
e
k
e
j
α
e
m
-
e
j
α
e
m
e
j
β
e
k
-
e
j
β
e
k
]
,
{
m
,
k
}
=
0
,
…
,
N
p
/
2
-
1
,
m
≠
k
,
{
α
,
β
}
=
0
,
π
/
2
wherein e m is a selection vector of length N p /2, N p is a total number of CSI-RS antenna ports.
13. The UE of claim 9 , wherein a value of “1” occupies an m th position of the vector and a value of “0” occupies other positions of the vector.
14. The UE of claim 4 , the UE to further:
calculate the CSI of the transmission channel using the codebook, wherein the codebook for rank 1 CSI reporting contains at least one element from the following set:
1
4
[
d
m
,
n
e
j
α
d
m
,
n
]
,
1
4
[
d
m
,
n
-
e
j
α
d
m
,
n
]
,
{
m
,
n
}
=
0
,
…
,
N
p
/
2
-
1
,
m
≠
n
,
{
α
}
=
0
,
π
/
2
wherein d m,n is a vector of length N p /2.
15. The UE of claim 4 , the UE to further:
calculate the CSI of the transmission channel using the codebook, wherein the codebook for rank 2 CSI reporting contains at least one element from the following set:
1
8
[
d
m
,
n
d
m
,
n
e
j
α
d
m
,
n
-
e
j
α
d
m
,
n
]
,
{
m
}
=
0
,
…
,
N
p
/
2
-
1
,
{
α
}
=
0
,
π
/
2
,
wherein d m,n is a vector of length N p /2.
16. The UE of claim 4 , the UE to further:
calculate the CSI of the transmission channel using the codebook, wherein the codebook for rank 3 CSI reporting contains at least one element from the following set:
1
12
[
d
m
,
n
d
m
,
n
d
k
,
l
e
j
α
d
m
,
n
-
e
j
α
d
m
,
n
e
j
β
d
k
,
l
]
1
12
[
d
m
,
n
d
k
,
l
d
k
,
l
e
j
α
d
m
,
n
e
j
β
d
k
,
l
-
e
j
β
d
k
,
l
]
,
{
m
,
n
}
,
{
k
,
l
}
=
0
,
…
,
N
p
/
2
-
1
,
m
≠
n
,
k
≠
l
,
{
α
,
β
}
=
0
,
π
/
2
wherein d m,n is a vector of length N p /2.
17. The UE of claim 4 , the UE to further:
calculate the CSI of the transmission channel using the codebook, wherein the codebook for rank 4 CSI reporting contains at least one element from the following set:
1
16
[
d
m
,
n
d
m
,
n
d
k
,
l
d
k
,
l
e
j
α
d
m
,
n
-
e
j
α
d
m
,
n
e
j
β
d
k
,
l
-
e
j
β
d
k
,
l
]
,
{
m
,
n
}
,
{
k
,
l
}
=
0
,
…
,
N
p
/
2
-
1
,
m
≠
n
,
k
≠
l
,
{
α
,
β
}
=
0
,
π
/
2
wherein d m,n is a vector of length N p /2.
18. The UE of claim 14 , wherein in vector d m,n a value of “1” occupies an m th position of the vector, a value of “−1” occupies an n th position of the vector, where m is unequal to n, and a value of “0” occupies other positions of the vector.
19. The UE of claim 14 , wherein in vector d m,n :
a value of “1” occupies the m th and n th positions of the vector, where m is unequal to n, and a value of “0” occupies the other positions of the vector; or
a value of “1” occupies the m th position, a value of “−1” occupies the n th positions of the vector, and a value of “0” occupies other positions of the vector.
20. The UE of claim 14 , wherein in vector d m,n a non-integer value occupies the m th and n th positions, where m is unequal to n, and a value of “0” occupies the other positions.
21. The UE of claim 14 , wherein the vector d m,n of length N p /2 includes non-integer values in the n th and m th elements (noted as d i ), where m is unequal to n, as follows:
d
i
=
{
d
m
,
i
=
m
d
n
,
i
=
n
0
,
otherwise
wherein m is not equal to n.
22. The UE of claim 1 , wherein the codebook follows an uplink codebook defined in TS 36.211 v. 11.4.0, section 5.3.3A.2 to support uplink transmissions.
23. An apparatus to operate in a cellular′ network, the apparatus comprising:
a plurality of antennas to receive and transmit signals;
a codebook comprising a matrix, the matrix comprising non-constant modulus elements, wherein a column of the matrix corresponds to a multiple-input-multiple-output (MIMO) layer and a row of the matrix corresponds to an antenna port and wherein a precoding vector among a plurality of vectors of the codebook contains at least two non-zero elements; and
baseband circuitry is configured to:
receive a radio frame comprising a channel state information reference signal (CSI-RS);
calculate channel state information (CSI) using both the CSI-RS and the codebook; and
report the CSI to the cellular network.
24. The apparatus of claim 23 , wherein the codebook comprises:
a first codebook comprising precoding matrices for rank 1, rank 2, rank 3, and rank 4, the first codebook comprising first selection vectors of length N p /2, where N p is a total number of CSI-RS antenna ports, wherein a value of “1” occupies an m th position and a value of “0” occupies other positions of the first selection vectors; and
a second codebook also comprising precoding matrices for rank 1, rank 2, rank 3, and rank 4, the second codebook comprising second selection vectors of length N p /2, wherein:
a value of “1” occupies n th and m th positions of the second selection vectors, where m is unequal to n, and a value of “0” occupies the other positions of the second selection vectors; or
a value of “1” occupies the m th position, a value of “−1” occupies the n th positions of the second selection vectors, and a value of “0” occupies other positions of the second selection vectors.