Channel state information (CSI) feedback and subsampling
View Patent ↗A method implemented in a base station used in a wireless communications system is disclosed. The method comprises receiving, from a user equipment, rank indication (RI), a first precoding matrix indicator (PMI), and a second PMI (codebook index i 2 ), wherein values 0-15 are assigned to the second PMI I PMI2 for RI=1 and values 0-3 are assigned to the second PMI I PMI2 for each of RI=2, RI=3, and RI=4, and wherein codebook index i 2 comprises I PMI2 for RI=1. Other methods, apparatuses, and systems also are disclosed.
1. A method implemented in a base station used in a wireless communications system, the method comprising:
receiving at the base station, from a user equipment, a rank indication (RI), a first precoding matrix indicator (PMI), and a second PMI (I PMI2 ) associated with a codebook index (i 2 ), for only four antenna ports, and
serving, by the base station, the user equipment based on the i 2 for a physical uplink control channel (PUCCH) mode of at least one antenna port,
wherein the codebook index i 2 is determined according to a table comprising:
Relationship between the second PMI
value and codebook index i 2
Value of the
second PMI
RI
I PMI 2
Codebook index i 2
1
0-15
I PMI 2
2
0-3
0, 1, 4, 5
3
0-3
0, 2, 8, 10
4
0-3
0, 2, 8, 10.
2. A method implemented in a user equipment used in a wireless communications system, the method comprising:
transmitting, to a base station, a rank indication (RI), a first precoding matrix indicator (PMI), and a second PMI (I PMI2 ) associated with a codebook index (i 2 ), for only four antenna ports, and
receiving a signal, from the base station, based on the i 2 for a physical uplink control channel (PUCCH) mode of at least one antenna port,
wherein the codebook index i 2 is determined according to a table comprising:
Relationship between the second PMI
value and codebook index i 2
Value of the
second PMI
RI
I PMI 2
Codebook index i 2
1
0-15
I PMI 2
2
0-3
0, 1, 4, 5
3
0-3
0, 2, 8, 10
4
0-3
0, 2, 8, 10.
3. The method as in claim 2 , wherein the codebook index i 2 is for physical uplink control channel (PUCCH) mode 2-1 codebook subsampling in LTE (Long Term Evolution).
4. The method as in claim 1 , wherein the codebook index i 2 is for physical uplink control channel (PUCCH) mode 2-1 codebook subsampling in LTE (Long Term Evolution).
5. A method implemented in a wireless communications system, the method comprising:
transmitting, from a user equipment to a base station, a rank indication (RI), a first precoding matrix indicator (PMI), and a second PMI (I PMI2 ) associated with a code book index (i 2 ), for only four antenna ports, and
receiving signals, from the base station, based on the i 2 for a physical uplink control channel (PUCCH) mode of at least one antenna port,
wherein the codebook index i 2 is determined according to a table comprising:
Relationship between the second PMI
value and codebook index i 2
Value of the
second PMI
RI
I PMI 2
Codebook index i 2
1
0-15
I PMI 2
2
0-3
0, 1, 4, 5
3
0-3
0, 2, 8, 10
4
0-3
0, 2, 8, 10.
6. A wireless communications system comprising:
a base station; and
a user equipment comprising at least one antenna port, the user equipment being configured to:
transmit, to the base station, a rank indication (RI), a first precoding matrix indicator (PMI), and a second PMI (I PMI2 ) associated with a code book index (i 2 ), for only four antenna ports; and
receive signals, from the base station, based on the i 2 for a physical uplink control channel (PUCCH) mode of the at least one antenna port,
wherein the codebook index i 2 is determined according to a table comprising:
Relationship between the second PMI
value and codebook index i 2
Value of the
second PMI
RI
I PMI 2
Codebook index i 2
1
0-15
I PMI 2
2
0-3
0, 1, 4, 5
3
0-3
0, 2, 8, 10
4
0-3
0, 2, 8, 10.
7. A base station comprising at least one antenna port, the base station being configured to:
receive, from a user equipment, a rank indication (RI), a first precoding matrix indicator (PMI), and a second PMI (I PMI2 ) associated with a codebook index (i 2 ), for only four antenna ports, and
serve the user equipment based on the i 2 for a physical uplink control channel (PUCCH) mode of at least one antenna port,
wherein the codebook index i 2 is determined according to a table comprising:
Relationship between the second PMI
value and codebook index i 2
Value of the
second PMI
RI
I PMI 2
Codebook index i 2
1
0-15
I PMI 2
2
0-3
0, 1, 4, 5
3
0-3
0, 2, 8, 10
4
0-3
0, 2, 8, 10.
8. The method as in claim 7 , wherein the codebook index i 2 is for physical uplink control channel (PUCCH) mode 2-1 codebook subsampling in LTE (Long Term Evolution).