Granted Patent B2

US 8,599,960 · App. 13/246,326 · Granted Dec 3, 2013

Abstract

Claims (39)

1. A method comprising:

determining a transmission rank and a precoding matrix for each of at least two transmission points of a plurality of transmission points;

determining a joint transmission rank based on at least two of the plurality of transmission points;

selecting a joint transmission precoding matrix from a plurality of candidate joint transmission precoding matrices generated from the determined precoding matrix for each of the at least two transmission points and the determined joint transmission rank; and

causing channel state information “CSI” to be transmitted to an access point, wherein the CSI describes the selected joint transmission precoding matrix.

2. The method of claim 1 further comprises causing at least one of the determined transmission ranks for each of the at least two transmission points, the determined precoding matrices for each of the at least two transmission points, the determined joint transmission rank or the selected joint transmission precoding matrix to be transmitted to the access point.

3. The method of claim 1 , wherein the joint transmission precoding matrix is diagonalized such that each of its associated spatial layers is transmitted by a transmission point of the plurality of transmission points.

4. The method of claim 1 , wherein the joint transmission precoding matrix is semi-diagonalized such that at least one of an associated spatial layers is transmitted by a transmission point of the plurality of transmission points and at least another associated spatial layer is transmitted jointly by at least two transmission points of the plurality of transmission points.

5. The method of claim 1 , wherein the joint transmission precoding matrix is formed based on a column permutation of the determined precoding matrices for at least one of the at least two transmission points.

6. The method of claim 1 , wherein the joint transmission precoding matrix comprises sub-matrices based on the determined precoding matrices for each of the at least two transmission points.

7. The method of claim 1 , wherein the determined precoding matrices for each of the at least two transmission points comprises an intra-transmission point precoder and an inter-transmission point combiner.

8. The method of claim 1 , wherein determining precoding matrices for each of the at least two transmission points further comprises determining a precoding matrix that is configured to optimize a performance metric.

9. The method of claim 1 , wherein selecting a joint transmission precoding matrix further comprises:

generating at least one of a plurality of candidate joint transmission precoding matrices, each of the generated plurality of candidate joint transmission precoding matrices being based on the determined precoding matrix for each of the at least two transmission points and the determined joint transmission rank;

selecting a generated candidate joint transmission precoding matrix from the plurality of generated candidate joint transmission precoding matrices based on a performance metric.

10. An apparatus comprising:

a processor and

a memory including software, the memory and the software configured to, with the processor, cause the apparatus to at least:

determine a transmission rank and a precoding matrix for each of at least two transmission points of a plurality of transmission points;

determine a joint transmission rank from a plurality of candidate joint transmission precoding matrices generated from at least two of the plurality of transmission points;

select a joint transmission precoding matrix based on the determined precoding matrix for each of the at least two transmission points and the determined joint transmission rank; and

cause channel state information “CSI” to be transmitted to an access point, wherein the CSI describes the selected joint transmission precoding matrix.

11. The apparatus of claim 10 wherein the at least one memory including the computer program code is further configured to, with the at least one processor, cause the apparatus to cause at least one of the determined transmission ranks for each of the at least two transmission points, the determined precoding matrices for each of the at least two transmission points, the determined joint transmission rank or the selected joint transmission precoding matrix to be transmitted.

12. The apparatus of claim 10 , wherein the joint transmission precoding matrix is diagonalized such that each of its associated spatial layers is transmitted by a transmission point of the plurality of transmission points.

13. The apparatus of claim 10 , wherein the joint transmission precoding matrix is semi-diagonalized such that at least one of an associated spatial layers is transmitted by a transmission point of the plurality of transmission points and at least another associated spatial layer is transmitted jointly by at least two transmission points of the plurality of transmission points.

14. The apparatus of claim 10 , wherein the joint transmission precoding matrix is formed based on a column permutation of the determined precoding matrices for at least one of the at least two transmission points.

15. The apparatus of claim 10 , wherein the joint transmission precoding matrix comprises sub-matrices based on the determined precoding matrices for each of the at least two transmission points.

16. The apparatus of claim 10 , wherein the determined precoding matrices for each of the at least two transmission points comprises an intra-transmission point precoder and an inter-transmission point combiner.

17. The method of claim 10 , wherein determining precoding matrices for each of the at least two transmission points further comprises determining a precoding matrix that is configured to optimize a performance metric.

18. The apparatus of claim 10 , wherein the at least one memory including the computer program code is further configured to, with the at least one processor, cause the apparatus to:

generate at least one of a plurality of candidate joint transmission precoding matrices, each of the generated plurality of candidate joint transmission precoding matrices being based on the determined precoding matrix for each of the at least two transmission points and the determined joint transmission rank;

select a generated candidate joint transmission precoding matrix from the plurality of generated candidate joint transmission precoding matrices based on a performance metric.

19. An apparatus comprising:

a processor and

a memory including software, the memory and the software configured to, with the processor, cause the apparatus to at least:

receive a report comprising at least one of transmission ranks for each of the at least two transmission points, precoding matrices for each of the at least two transmission points, a joint transmission rank or a joint transmission precoding matrix, wherein the joint transmission precoding matrix is selected by a mobile terminal from a plurality of generated candidate joint transmission precoding matrices based on a performance metric;

determine a transmission strategy based on the received report; and

cause a transmission using at least one of the precoding matrices for each of the at least two transmission points or the joint transmission precoding matrix.

20. The apparatus according to claim 19 , wherein the at least one memory including the computer program code is further configured to, with the at least one processor, cause the apparatus to determine whether at least one of multiple user multiple input multiple output or single user multiple input multiple output will be used based on the received report.

Assignments (9)