METHOD AND APPARATUS FOR SELECTING USER TERMINAL IN MOBILE COMMUNICATION SYSTEM

• US 20150263794A1
• Filed: 10/16/2013
• Published: 09/17/2015
• 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, Inkyu, Lee, Kwang Won, An, Min Ki, Lee, Kil-Bom
• Granted Patent: US 9,621,233 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• 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 for user equipment (UE) selection in a mobile communication system, the method comprising:

selecting a n−

1^th UE in a plurality of cells, wherein n is greater than or equal to two; and

selecting a UE with a maximum weighted sum rate (WSR) as an n^th UE from among one or more UEs belonging to remaining cells that exclude cells containing a 1^st UE to the n−

1^th UE.

2. The method of claim 1, wherein selecting the UE with the maximum WSR as the n^th UE comprises:

computing a WSR for each of the UEs belonging to the remaining cells that exclude the cells containing the 1^st UE to the n−

1^th UE from the plurality of cells;

comparing the maximum WSR among the computed WSRs with a WSR of the n−

1^th UE; and

selecting, when the maximum WSR is greater than the WSR of the n−

1^th UE, the UE with the maximum WSR as the n^th UE.

3. The method of claim 2, wherein computing the WSR for each of the UEs belonging to the remaining cells comprises:

performing beamforming with all of the UEs belonging to the remaining cells that exclude the cells containing the 1^st UE to the n−

1^th UE and with the 1^st UE to the n−

1^th UE;

computing weighted rates (WR) of the 1^st UE to the n−

1^th UE and all of the UEs belonging to the remaining cells that exclude the cells containing the 1^st UE to the n−

1^th UE using a signal-to-interference-plus-noise-ratio (SINR) computed based on global channel state information (global CSI); and

computing the WSR for each of the 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 computing the WSR for each of the UEs belonging to the remaining cells comprises:

receiving, from each cell, weighted virtual rates (WVR) of each of the UEs belonging to each of the cells; and

computing a weighted sum virtual rate (WSVR) using the received WVRs, wherein the WVR computation is performed by each of the cells based on local cannel 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 n is equal to a total number of cells; and

selecting, when n is not equal to the total number of cells, an n+1^th UE.

8. The method of claim 7, further comprising stopping the user equipment selection when n is equal to the total number of cells.

9. The method of claim 2, further comprising stopping the user equipment selection when the maximum WSR is less than the WSR of the n−

1^th UE after the comparison.

10. The method of claim 1, wherein selecting the n−

1^th UE in the plurality of the cells comprises;

computing WRs for all of the UEs in the plurality of the cells; and

selecting a UE with the maximum WR as a 1^st UE from among all of the UEs in the plurality of the cells.

11. An apparatus for user equipment (UE) selection in a mobile communication system, the apparatus comprising a controller configured to:

select an n−

1^th UE in multiple plurality of cells, wherein n is greater than or equal to two, and

selecting a UE with a maximum weighted sum rate (WSR) as an n^th UE from among one or more UEs belonging to remaining cells that exclude cells containing a 1^st UE to the n−

1^th UE.

12. The apparatus of claim 11, wherein the controller is configured to select the UE with the maximum WSR as the n^th UE by:

computing a WSR for each of the UEs belonging to the remaining cells that exclude the cells containing the 1^st UE to the n−

1^th UE from the the plurality of cells,

comparing the maximum WSR among the computed WSRs with a WSR of the n−

1^th UE, and

selecting, when the maximum WSR is greater than the WSR of the n−

1^th UE, the UE with the maximum WSR as the n^th UE.

13. The apparatus of claim 12, wherein the controller is configured to compute the WSR for each of the UEs belonging to the remaining cell by:

performing beamforming with all of the UEs belonging to the remaining cells that exclude the cells containing the 1^st UE to the n−

1^th UE and with the 1^st UE to the n−

1^th UE,

computing weighted rates (WR) of the 1^st UE to the n−

1^th UEs and all of the UEs belonging to the remaining cells that exclude the cells containing the 1^st UE to the n−

1^th UE using a signal-to-interference-plus-noise-ratio (SINR) computed based on global channel state information (global CSI), and

computing the WSR for each of the UEs based on the computed WRs.

14. The apparatus of claim 13, wherein the WSR computation is performed using the following equation:

15. The apparatus of claim 12, wherein the controller is configured to compute the WSRs for each of the UEs belonging to the remaining cells by:

receiving, from each cell, weighted virtual rates (WVR) of each of the UEs belonging to each of the cells, and

computing a weighted sum virtual rate (WSVR) using the received WVRs, wherein the WVR computation is performed by each of the cells based on local cannel state information (local CSI).

16. The apparatus of claim 15, 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;

17. The apparatus of claim 12, wherein the controller is configured to:

check whether n is equal to a total number of cells, and

select an n+1^th UE when n is not equal to the total number of cells.

18. The apparatus of claim 17, wherein the controller configured to stop the user equipment selection when n is equal to the total number of cells.

19. The apparatus of claim 12, wherein the controller configured to stop the user equipment selection when the maximum WSR is less than the WSR of the n−

1^th UE after the comparison.

20. The apparatus of claim 11, wherein the controller is configured to select the n−

1^th UE by;

computing WRs for all of the UEs in the plurality of the cells, and

selecting a UE with the maximum WR as a 1^st UE from among all of the UEs in the plurality of the cells.