Method and apparatus for selecting user terminal in mobile communication system

• US 9,621,233 B2
• Filed: 10/16/2013
• Issued: 04/11/2017
• Est. Priority Date: 10/16/2012
• Status: Active Grant

• Current Assignee: Korea University Research and Business Foundation, Samsung Electronics Co. Ltd.
• Original Assignee: Korea University Research and Business Foundation, Samsung Electronics Co. Ltd.
• Inventors: Lee, Kwang Won, Lee, Inkyu, An, Min Ki, Lee, Kil-Bom
• Primary Examiner(s): Perez, James M
• Application Number:
  US14/436,442
• Publication Number:
  US 20150263794A1
• Time in Patent Office: 1,273 Days
• Field of Search: 375259-285, 375295-352
• CPC Class Codes: H04B 7/024 Co-operative use of antennas of several sites, e.g. in co-ordinated multipoint or co-operative multiple-input multiple-output [MIMO] systems
• CPC Class Codes: H04B 7/0452 Multi-user MIMO systems
• CPC Class Codes: H04L 1/0026 Transmission of channel quality indication
• CPC Class Codes: H04L 1/0033 arrangements specific to the transmitter
• CPC Class Codes: H04W 16/28 using beam steering

Abstract

Provided are a method and apparatus for user equipment (UE) selection in a mobile communication system. The method may include: selecting the n−1^th UE in multiple cells (n: constant ≧2); and selecting a UE with the maximum weighted sum rate (WSR) as the n^th UE from among UEs belonging to the remaining cells excluding those cells containing the 1^st to n−1^th UEs. Hence, the scheduling function enabling suitable user equipment selection may further increase overall system throughput by providing additional gains in addition to beamforming, i.e. further reducing inter-cell interference and increasing signal strength toward a desired user equipment.

Claims

1. A method by a central unit controlling at least two base stations in a mobile communication system, the method comprising:

receiving channel state information (CSI) of a plurality of user equipments (UEs) from a plurality of base stations;

selecting a first UE in a cell of a plurality of cells of the plurality of base stations, wherein the first UE comprises a maximum weight rate (WR) among the plurality of UEs;

selecting a second UE that maximizes a weighted sum rate (WSR) of a plurality of UEs belonging to cells different from a cell containing the first UE; and

transmitting scheduling information to each of the plurality of base stations based on the selection of the first UE and the second UE.

2. The method of claim 1, wherein selecting the second UE comprises:

identifying a maximum WSR by computing the WSR of the plurality of UEs belonging to the cells different from the cell containing the first UE;

comparing the identified maximum WSR with a WSR related to the first UE; and

selecting, if the identified maximum WSR is greater than the WSR related to the first UE, a UE that makes the identified maximum WSR as the second UE.

3. The method of claim 2, wherein identifying the maximum WSR comprises:

performing beamforming with the plurality of UEs belonging to the cells different from the cell containing the first UE;

computing WRs of the plurality of UEs belonging to the cells different from the cell containing the first UE using a signal-to-interference-plus-noise-ratio (SINR) computed based on global channel state information (global CSI); and

computing the WSR of the plurality of UEs based on the computed WRs.

4. The method of claim 3, wherein the WSR computation is performed using the following equation:

5. The method of claim 2, wherein identifying the maximum WSR comprises:

receiving weighted virtual rates (WVR) of the plurality of UEs belonging to the cells different from the cell containing the first UE; and

computing a weighted sum virtual rate (WSVR) using the received WVRs,

wherein the WVR computation is performed by the cells different from the cell containing the first UE based on local channel state information (local CSI).

6. The method of claim 5, wherein the WVR computation is performed using the following equation:

WVR=(w_ki log₂ Π

_i<sup>−

1</sup>),

and wherein the WSVR computation is performed using the following equation;

7. The method of claim 2, further comprising:

checking whether a total number of the selected UEs is equal to a total number of cells; and

selecting, if the total number of the selected UEs is not equal to the total number of cells, a third UE.

8. The method of claim 7, further comprising stopping the UE selection if the total number of the selected UEs is equal to the total number of cells.

9. The method of claim 2, further comprising stopping the UE selection if the maximum WSR is less than the WSR of the first UE after the comparison.

10. A central unit controlling at least two base stations in a mobile communication system, the central unit comprising:

a transceiver configured to transmit and receive a signal; and

a controller configured to;

receive channel state information (CSI) of a plurality of user equipments (UEs) from a plurality of base stations,

select a first UE in a cell of a plurality of cells of the plurality of base stations, wherein the first UE comprises a maximum weight rate (WR) among the plurality of UEs,

select a second UE that maximizes a weighted sum rate (WSR) of a plurality of UEs belonging to cells different from a cell containing the first UE, and

transmit scheduling information to each of the plurality of base stations based on the selection of the first UE and the second UE.

11. The central unit of claim 10, wherein the controller is configured to select the second UE by:

identifying a maximum WSR by computing the WSR of the plurality of UEs belonging to the cells different from the cell containing the first UE,

comparing the identified maximum WSR with a WSR related to the first UE, and

selecting, if the identified maximum WSR is greater than the WSR related to the first UE, a UE that makes the identified maximum WSR as the second UE.

12. The central unit of claim 11, wherein the controller is configured to identify the maximum WSR by:

performing beamforming with the plurality of UEs belonging to the cells different from the cell containing the first UE,

computing WRs of the plurality of UEs belonging to the cells different from the cell containing the first UE using a signal-to-interference-plus-noise-ratio (SINR) computed based on global channel state information (global CSI), and

computing the WSR of the plurality of UEs based on the computed WRs.

13. The central unit of claim 12, wherein the WSR computation is performed using the following equation:

14. The central unit of claim 11, wherein the controller is configured to identify the maximum WSR by:

receiving weighted virtual rates (WVR) of the plurality of UEs belonging to the cells different from the cell containing the first UE, and

computing a weighted sum virtual rate (WSVR) using the received WVRs,

wherein the WVR computation is performed by the cells different from the cell containing the first UE based on local channel state information (local CSI).

15. The central unit of claim 14, wherein the WVR computation is performed using the following equation:

WVR=(w_ki log₂ Π

_i<sup>−

1</sup>),

and wherein the WSVR computation is performed using the following equation;

16. The central unit of claim 11, wherein the controller is configured to:

check whether a total number of the selected UEs is equal to a total number of cells, and

select a third UE if the total number of the selected UEs is not equal to the total number of cells.

17. The central unit of claim 16, wherein the controller is configured to stop the UE selection if the total number of the selected UEs is equal to the total number of cells.

18. The central unit of claim 11, wherein the controller is configured to stop the UE selection if the maximum WSR is less than the WSR of the first UE after the comparison.