Method for Performing Handover in Wireless Communication System

• US 20130223409A1
• Filed: 11/04/2011
• Published: 08/29/2013
• Est. Priority Date: 11/05/2010
• Status: Active Grant

• Current Assignee: LG Electronics, Inc. (LG Corporation)
• Original Assignee: LG Electronics, Inc. (LG Corporation)
• Inventors: Jung, Sung Hoon, Yi, Seung June, Lee, Young Dae, Chun, Sung Duck, Park, Sung Jun
• Granted Patent: US 9,603,073 B2
• Time in Patent Office: Days
• US Class Current: 370/331
• CPC Class Codes: H04W 36/0072 of resource information of target access point
• CPC Class Codes: H04W 36/20 for optimising the interference level

Abstract

Provided is a method for a user equipment performing a handover in a wireless communication system. The method comprises a step of receiving from a source cell a handover command message, which indicates the handover to a target cell, and a step of performing the handover to the target cell, wherein the handover command message includes information on a low-interference wireless resource to be used by the user equipment inside the target cell. The low-interference wireless resource can be a wireless resource which is operated by the source cell in order to mitigate inter-cell interference, when the source cell is an interfering cell and the target cell is an interfered cell.

Claims

1. A handover method performed by User Equipment (UE) in a wireless communication system, comprising the steps of:

receiving a handover command message indicating handover to a target cell from a source cell, and

performing the handover with the target cell,

wherein the handover command message comprises information on low-interference radio resources to be used by the UE within the target cell.

2. The handover method of claim 1, wherein the low-interference radio resources are radio resources operated by the source cell in order to reduce inter-cell interference when the source cell is an interfering cell and the target cell is an interfered cell.

3. The handover method of claim 2, wherein the low-interference radio resources comprise one or more Almost Blank Subframes (ABSs).

4. The handover method of claim 3, wherein the step of performing the handover comprises:

transmitting a random access preamble,

receiving a random access response message in response to the random access preamble, and

transmitting a handover confirm message to the target cell.

5. The handover method of claim 4, wherein the step of performing the handover further comprises controlling timing at which the random access preamble is transmitted so that the random access response message can be received through the low-interference radio resources.

6. The handover method of claim 5, wherein receiving the random access response message comprises receiving the random access response message through the low-interference radio resources.

7. The handover method of claim 6, wherein transmitting the random access preamble comprises transmitting the random access preamble using the low-interference radio resources.

8. The handover method of claim 7, further comprising the step of initiating measurement of the target cell using the low-interference radio resources after completing the handover.

9. The handover method of claim 8, wherein:

the source cell is a macro cell, and

the target cell is a pico cell which operates coverage overlapped with coverage of the macro cell.

10. An apparatus for performing measurement in a wireless communication system, comprising:

a Radio Frequency (RF) unit transmitting and receiving radio signals; and

a processor connected to the RF unit, wherein the processor is configured to;

receive a handover command message indicating handover to a target cell from a source cell, and

perform the handover with the target cell, and

the handover command message comprises information on low-interference radio resources to be used by the UE within the target cell.

11. The apparatus of claim 10, wherein the low-interference radio resources are radio resources operated by the source cell in order to reduce inter-cell interference when the source cell is an interfering cell and the target cell is an interfered cell.

12. The apparatus of claim 11, wherein the low-interference radio resources comprise one or more Almost Blank Subframes (ABSs).

13. The apparatus of claim 12, wherein performing the handover comprises:

transmitting a random access preamble,

receiving a random access response message in response to the random access preamble, and

transmitting a handover confirm message to the target cell.

14. The apparatus of claim 13, wherein performing the handover further comprises controlling timing at which the random access preamble is transmitted so that the random access response message can be received through the low-interference radio resources.

15. The apparatus of claim 14, wherein receiving the random access response message comprises receiving the random access response message through the low-interference radio resources.

16. The apparatus of claim 15, wherein transmitting the random access preamble comprises transmitting the random access preamble using the low-interference radio resources.

17. A handover method performed by a source cell in a wireless communication system, comprising:

receiving a result of restrictive measurement from User Equipment (UE), wherein the result of measurement is a result of measurement based on low-interference radio resources configured by a source cell,

determining a target cell which is an object of handover based on the result of the restrictive measurement,

transmitting a handover request message to the target cell, receiving a handover request acknowledgement (ACK) message in response to the handover request message, and

transmitting a handover command message indicating of the handover to the target cell the UE,

wherein the handover command message comprises information on the low-interference radio resources to be used by the UE within the target cell.

18. The handover method of claim 17, wherein the low-interference radio resources are radio resources operated by the source cell in order to reduce inter-cell interference when the source cell is an interfering cell and the target cell is an interfered cell.

19. The handover method of claim 18, wherein the low-interference radio resources comprise one or more Almost Blank Subframes (ABSs).

20. The handover method of claim 19, wherein the handover request message comprises information indicating that the handover has been triggered by the restrictive measurement.

21. The handover method of claim 20, wherein the handover request message further comprises the information on the low-interference radio resources.

22. The handover method of claim 21, wherein the handover ACK message comprises at least one of information indicating that the UE uses the low-interference radio resources within the target cell and the information on the low-interference radio resources.