Beamforming for increasing cell edge capacity in a heterogeneous network

• US 8,792,896 B2
• Filed: 10/09/2012
• Issued: 07/29/2014
• Est. Priority Date: 10/09/2012
• Status: Active Grant

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Boudreau, Gary, Ahmad, Talha
• Primary Examiner(s): Ly, Nghi H
• Application Number:
  US13/647,753
• Publication Number:
  US 20140099960A1
• Time in Patent Office: 658 Days
• Field of Search: 455/438, 455/436, 455/442, 455/422.1, 455/432.1, 455/435.1, 455/423, 455/418, 370/331
• US Class Current: 455/438
• CPC Class Codes: H04B 7/022 Site diversity; Macro-diversity using two or more spaced independent antennas H04B7/04
• CPC Class Codes: H04B 7/0615 of weighted versions of same signal
• CPC Class Codes: H04W 36/302 due to low signal strength

Abstract

Methods of communicating with a selected user equipment terminal (UE) in a first cell served by a base station and a remote radio head include forming a list of non-targeted UEs including other UEs in the first cell and cell edge UEs in a neighboring cell that borders the first cell that are located near a border of the first cell and the neighboring cell, generating a list of candidate precoding matrices that can be used to communicate with the selected UE from the base station and/or from the remote radio head, generating a list of available precoding matrices by discarding from the list of candidate precoding matrices those precoding matrices that may cause interference to at least one non-targeted UE, selecting a precoding matrix from the list of available precoding matrices, and communicating with the selected UE using the selected precoding matrix.

Claims

1. A method of communicating with a selected user equipment terminal (UE) in a first cell served by a base station and a remote radio head, the method comprising:

forming a list of non-targeted UEs including other UEs in the first cell, and cell edge UEs in a neighboring cell that borders the first cell that are located near a border of the first cell and the neighboring cell, the list including geographic locations and signal to interference plus noise ratios (SINRs) of the non-targeted UEs;

generating a list of candidate precoding matrices that can be used to communicate with the selected UE from the base station and/or from the remote radio head;

generating a list of available preceding matrices by discarding from the list of candidate preceding matrices those preceding matrices that may cause interference to at least one non-targeted UE;

selecting a preceding matrix from the list of available preceding matrices; and

communicating with the selected UE using the selected preceding matrix.

2. The method of claim 1, wherein discarding preceding matrices from the list of candidate preceding matrices comprises discarding from the list of candidate preceding matrices those preceding matrices that generate a beam that causes interference to at least one non-targeted UE.

3. The method of claim 1, further comprising iteratively generating a list of available preceding matrices and selecting a preceding matrix from the list of available preceding matrices for each UE in the first cell.

4. The method of claim 1, wherein communicating with the selected UE using the selected precoding matrix comprises communicating with the selected UE using the selected precoding matrix by the remote radio head.

5. The method of claim 1, further comprising discarding UEs from the list of non-targeted UEs that are served on a different frequency than a frequency on which the targeted UE is served before generating the list of available preceding matrices.

6. The method of claim 5, wherein local UEs in a central region within the first cell are served using a first frequency and where local UEs in a cell-edge region near a boundary of the first cell with the neighboring cell are served using a second frequency that is different from the first frequency.

7. The method of claim 6, wherein cell edge UEs in the neighboring cell are served using a third frequency that is different from the second frequency and the first frequency.

8. The method of claim 1, further comprising generating a list of picocell UEs served by one or more picocells defined within the first cell, and combining the list of picocell UEs with the list of local UEs in the cell and the list, of cell edge UEs to form the combined list of non-targeted UEs.

9. The method of claim 1, wherein each of the base station, each of the remote radio head and the targeted UE includes a plurality of antennas.

10. The method of claim 1, further comprising discarding UEs from the list of non-targeted UEs that are served on a different resource block than the selected UE.

11. A network node in a wireless communication network including a selected user equipment terminal (UE) in a first cell served by the base station and one or more remote radio heads, comprising:

a processor coupled to a plurality of transceivers having respective antennas, wherein the processor is configured to form a list of non-targeted UEs including other UEs in the first cell and cell edge UEs in a neighboring cell that borders the first cell that are located near a border of the first cell and the neighboring cell, the list including geographic locations and signal to interference plus noise ratios (SINRs) of the non-targeted UEs;

wherein the processor is further configured to generate a list of candidate precoding matrices that can be used to communicate with the selected UE from the base station and/or from the remote radio head, to discard from the list of candidate precoding matrices those precoding matrices that are likely to cause interference to at least one non-targeted UE to generate a list of available precoding matrices, and to select a precoding matrix from the list of available preceding matrices for communicating with the selected UE.

12. The network node of claim 11, wherein the processor is further configured to discard from the list of candidate precoding matrices those preceding matrices that generate a beam that covers at least one non-targeted UE.

13. The network node of claim 11, wherein the processor is further configured to iteratively generate a list of available precoding matrices and select a preceding matrix from the list of available precoding matrices for each UE in the first cell.

14. The network node of claim 11, wherein the processor is further configured to instruct the remote radio head to communicate with the selected UE using the selected preceding matrix.

15. The network node of claim 11, wherein the processor is further configured to discard UEs from the list of non-targeted UEs that are served on a different frequency than a frequency on which the targeted UE is served before generating the list of available precoding matrices.

16. The network node of claim 15, wherein local UEs in a central region within the first cell are served using a first frequency and where local UEs in a cell-edge region near a boundary of the first cell with the neighboring cell are served using a second frequency that is different from the first frequency.

17. The network node of claim 16, wherein cell edge UEs in the neighboring cell are served using a third frequency that is different from the second frequency and the first frequency.

18. The network node of claim 11, wherein the processor is further configured to generate a list of picocell UEs served by one or more picocells defined within the first cell, and combine the list of picocell UEs with the list of local UEs in the cell and the list of cell edge UEs to form the combined list of non-targeted UEs.

19. The network node of claim 11, wherein the processor is further configured to discard UEs from the list of non-targeted UEs that are served on a different resource block than the selected UE.

20. A non-transitory computer program product for communicating with a selected user equipment terminal (UE) in a first cell served by a base station and a remote radio head, the computer program product comprising:

a non-transitory computer readable storage medium having non-transitory computer readable program code embodied in the medium, the computer readable program code comprising;

computer readable program code configured to form a list of non-targeted UEs including other UEs in the first cell and cell edge UEs in a neighboring cell that borders the first cell that are located near a border of the first cell and the neighboring cell, the list including geographic locations and signal to interference plus noise ratios (SINRs) of the non-targeted UEs,

computer readable program code configured to generate a list of candidate precoding matrices that can be used to communicate with the selected UE from the base station and/or from the remote radio head;

computer readable program code configured to discard from the list of candidate precoding matrices those precoding matrices that may cause interference to at least one non-targeted UE to generate a list of available precoding matrices;

computer readable program code configured to select a precoding matrix from the list of available precoding matrices; and

computer readable program code configured to communicate with the selected UE using the selected precoding matrix.