Precoding for time or frequency correlated MIMO channels
View Patent ↗A method implemented in a base station is disclosed. The method includes precoding data with a precoder, and transmitting the precoded data to a user equipment, and the precoder can be expressed as multiplication OV where V is a first matrix corresponding to a first indication of the precoder for a group of transmitted symbols, and O is a second matrix corresponding to a second indication of the precoder for a variation in a channel. Other methods and apparatuses also are disclosed.
1. A method implemented in a base station used in a wireless communications system, the method comprising:
precoding data with a precoder; and
transmitting the precoded data to a user equipment,
wherein the precoder can be expressed as multiplication OV where O is multiplied by V in the order of OV in a non-commutative manner, V is a first matrix corresponding to a first indication of the precoder for a group of transmitted symbols, and O is a second matrix corresponding to a second indication of the precoder for a variation in a channel.
2. The method as in claim 1 , further comprising:
receiving from the user equipment the first indication of the precoder; and
receiving from the user equipment the second indication of the precoder.
3. The method as in claim 1 , wherein the variation is in at least one of time, frequency, and OFDM tones.
4. The method as in claim 1 , wherein the channel is correlated in at least one of time and frequency.
5. The method as in claim 1 , wherein the group of transmitted symbols are transmitted in a chunk of adjacent OFDM tones.
6. The method as in claim 1 , wherein matrix O is a differential precoder.
7. The method as in claim 1 , wherein matrix O is a unitary matrix.
8. The method as in claim 1 , wherein the first indication is quantized with B 1 bits and the second indication is quantized with B 2 bits where B 2 ≦B 1 .
9. A base station used in a wireless communications system, the base station comprising:
a precoding unit to precode data with a precoder; and
a transmission unit to transmit the precoded data to a user equipment,
wherein the precoder can be expressed as multiplication OV where O is multiplied by V in the order of OV in a non-commutative manner, V is a first matrix corresponding to a first indication of the precoder for a group of transmitted symbols, and O is a second matrix corresponding to a second indication of the precoder for a variation in a channel.
10. The base station as in claim 9 , further comprising:
a receiving unit to receive from the user equipment the first indication of the precoder and the second indication of the precoder.
11. The base station as in claim 9 , wherein the variation is in at least one of time, frequency, and OFDM tones.
12. The base station as in claim 9 , wherein the channel is correlated in at least one of time and frequency.
13. The base station as in claim 9 , wherein the group of transmitted symbols are transmitted in a chunk of adjacent OFDM tones.
14. The base station as in claim 9 , wherein matrix O is a differential precoder.
15. The base station as in claim 9 , wherein matrix O is a unitary matrix.
16. The base station as in claim 9 , wherein the first indication is quantized with B 1 bits and the second indication is quantized with B 2 bits where B 2 ≦B 1 .
17. A method implemented in a user equipment used in a wireless communications system, the method comprising:
receiving, from a base station, data precoded with a precoder,
wherein the precoder can be expressed as multiplication OV where O is multiplied by V in the order of OV in a non-commutative manner, V is a first matrix corresponding to a first indication of the precoder for a group of transmitted symbols and O is a second matrix corresponding to a second indication of the precoder for a variation in a channel.
18. The method as in claim 17 , further comprising:
transmitting to the base station the first indication of the precoder; and
transmitting to the base station the second indication of the precoder.
19. The method as in claim 17 , wherein the variation is in at least one of time, frequency, and OFDM tones.
20. The method as in claim 17 , wherein the channel is correlated in at least one of time and frequency.
21. The method as in claim 17 , wherein the group of transmitted symbols are transmitted in a chunk of adjacent OFDM tones.
22. The method as in claim 17 , wherein matrix O is a differential precoder.
23. The method as in claim 17 , wherein matrix O is a unitary matrix.
24. The method as in claim 17 , wherein the first indication is quantized with B 1 bits and the second indication is quantized with B 2 bits where B 2 ≦B 1 .
25. A user equipment used in a wireless communications system, the user equipment comprising:
a receiving unit to receive, from a base station, data precoded with a precoder,
wherein the precoder can be expressed as multiplication OV where O is multiplied by V in the order of OV in a non-commutative manner, V is a first matrix corresponding to a first indication of the precoder for a group of transmitted symbols and O is a second matrix corresponding to a second indication of the precoder for a variation in a channel.
26. The user equipment as in claim 25 , further comprising:
a transmission unit to transmit to the base station the first indication of the precoder and the second indication of the precoder.
27. The user equipment as in claim 25 , wherein the variation is in at least one of time, frequency, and OFDM tones.
28. The user equipment as in claim 25 , wherein the channel is correlated in at least one of time and frequency.
29. The user equipment as in claim 25 , wherein the group of transmitted symbols are transmitted in a chunk of adjacent OFDM tones.
30. The user equipment as in claim 25 , wherein matrix O is a differential precoder.
31. The user equipment as in claim 25 , wherein matrix O is a unitary matrix.
32. The user equipment as in claim 25 , wherein the first indication is quantized with B 1 bits and the second indication is quantized with B 2 bits where B 2 ≦B 1 .
33. A method implemented in a wireless communications system, the method comprising:
precoding data with a precoder; and
transmitting the precoded data from a base station to a user equipment,
wherein the precoder can be expressed as multiplication OV where O is multiplied by V in the order of OV in a non-commutative manner, V is a first matrix corresponding to a first indication of the precoder for a group of transmitted symbols, and O is a second matrix corresponding to a second indication of the precoder for a variation in a channel.
34. A wireless communications system comprising:
a base station to precode data with a precoder; and
a user equipment to receive the precoded data from the base station,
wherein the precoder can be expressed as multiplication OV where O is multiplied by V in the order of OV in a non-commutative manner, V is a first matrix corresponding to a first indication of the precoder for a group of transmitted symbols, and O is a second matrix corresponding to a second indication of the precoder for a variation in a channel.