METHOD FOR PERFORMING HANDOVER DURING DEVICE-TO-DEVICE COMMUNICATION IN WIRELESS ACCESS SYSTEM AND DEVICE FOR SAME

• US 20140135019A1
• Filed: 07/16/2012
• Published: 05/15/2014
• Est. Priority Date: 07/15/2011
• Status: Active Grant

• Current Assignee: LG Electronics, Inc. (LG Corporation)
• Original Assignee: LG Electronics, Inc. (LG Corporation)
• Inventors: Jang, Jiwoong, Cho, Hangyu
• Granted Patent: US 9,155,002 B2
• Time in Patent Office: Days
• US Class Current: 455/437
• CPC Class Codes: H04W 36/0016 Hand-off preparation specially adapted for end-to-end data sessions
• CPC Class Codes: H04W 36/302 due to low signal strength
• CPC Class Codes: H04W 76/23 Manipulation of direct-mode connections
• CPC Class Codes: H04W 88/04 adapted for relaying to or from another terminal or user

Abstract

A method and apparatus for performing a handover during a device-to-device communication in a wireless access system are disclosed. More particularly, the method comprises: a first device sensing a handover state by considering a link quality with a second device while performing device-to-device communication with the second device; the first device measuring channel quality with respect to neighboring devices by using a reference signal that is transmitted from the neighboring devices; the first device transmitting a handover request message to a relay device in order to start handover the relay device selected from the neighboring devices based on measuring channel quality; the first device receiving from the relay device a handover completion message indicating the completion of resource allocation; and the first device performing the device-to-device communication with the second device by using a resource that is allocated by the relay device.

Claims

1. A method for performing handover during device-to-device (D2D) communication in a radio access system supporting D2D communication, the method comprising:

sensing, by a first device, a handover state in consideration of link quality with a second device while performing communication with the second device;

measuring, by the first device, channel quality for a neighboring device using a reference signal transmitted from the neighboring device;

transmitting, by the first device, a handover request message to a relay device in order to start handover to the relay device selected from among the neighboring device based on the result of measuring channel quality;

receiving, by the first device from the relay device, a handover complete message indicating that resource allocation has been completed; and

performing, by the first device, D2D communication with the second device via the relay device using resources allocated by the relay device.

2. The method according to claim 1, further comprising broadcasting, by the first device, a request message for requesting transmission of the reference signal to the neighboring device.

3. The method according to claim 2, wherein the measuring the channel quality includes the first device measuring channel quality for the neighboring device immediately or a predetermined time elapsed after broadcasting the request message for requesting transmission of the reference signal to the neighboring device.

4. The method according to claim 1, further comprising receiving from the second device a list of neighboring devices having a channel quality value equal to or greater than a predetermined threshold for the second device,

wherein the measuring the channel quality includes the first device measuring channel quality for the neighboring device using a reference signal received from a device included in the list.

5. The method according to claim 1, further comprising transmitting, by the first device to the second device, a list of neighboring devices having a channel quality value equal to or greater than a predetermined threshold,

wherein the relay device is selected from among devices belonging to the list based on a channel quality value between a device belonging to the list and the second device.

6. The method according to claim 1, further comprising alternately performing, by the first device, communication with the relay device and communication with the second device until receiving the handover complete message from the relay device.

7. A method for performing handover during device-to-device (D2D) communication in a radio access system supporting D2D communication, the method comprising:

confirming, by a first device, that a second device has requested transmission of a reference signal from a neighboring device while performing D2D communication with the second device;

measuring, by the first device, channel quality for the neighboring device using the reference signal transmitted from the neighboring device;

transmitting, by the first device, a handover request message to a relay device in order to start handover to the relay device selected from among the neighboring device based on the result of measuring channel quality;

receiving, by the first device from the relay device, a handover complete message indicating that resource allocation has been completed; and

performing, by the first device, D2D communication with the second device via the relay device using resources allocated by the relay device.

8. The method according to claim 7, wherein the confirming includes receiving a request message broadcast to the neighboring device by the second device in order to request transmission of the reference signal and confirming that the second device has requested transmission of the reference signal from the neighboring device.

9. The method according to claim 7, wherein the confirming includes receiving, from the second device, an indication message indicating that the second device has broadcasted a request message for requesting transmission of the reference signal from the neighboring device and confirming that the second has requested transmission of the reference signal from the neighboring device.

10. The method according to claim 7, wherein the measuring the channel quality includes the second device measuring channel quality for the neighboring device immediately after confirming that the second device has requested transmission of the reference signal from the neighboring device or after a predetermined time has elapsed.

11. The method according to claim 7, further comprising receiving, by the first device from the second device, a list of neighboring devices having a channel quality value equal to or greater than a predetermined threshold for the second device,

wherein the measuring the channel quality includes measuring channel quality for the neighboring device using a reference signal received from a device included in the list.

12. The method according to claim 7, further comprising transmitting, by the first device to the second device, a list of neighboring devices having a channel quality value equal to or greater than a predetermined threshold,

wherein the relay device is selected from among devices belonging to the list based on a channel quality value between a device belonging to the list and the second device.

13. The method according to claim 7, further comprising alternately performing, by the first device, communication with the relay device and communication with the second device until receiving the handover complete message from the relay device.

14. A device for performing handover during device-to-device (D2D) communication in a radio access system supporting D2D communication, the device comprising:

a radio frequency (RF) unit configured to transmit and receive a radio signal; and

a processor configured to measure channel quality for a neighboring device using a reference signal transmitted from the neighboring device when sensing a handover state in consideration of link quality with another device while performing D2D communication with the another device, to transmit a handover request message to a relay device in order to start handover to the relay device selected from among the neighboring device based on the result of measuring the channel quality, and to perform D2D communication with the another device via the relay device using resources allocated by the relay device when receiving a handover complete message indicating that resource allocation has been completed from the relay device.

15. A device for performing handover during device-to-device (D2D) communication in a radio access system supporting D2D communication, the device comprising:

a radio frequency (RF) unit configured to transmit and receive a radio signal; and

a processor configured to confirm that another device has requested transmission of a reference signal from a neighboring device while performing D2D communication with the another device, to measure channel quality for the neighboring device using the reference signal transmitted from the neighboring device, to transmit a handover request message to a relay device in order to start handover to the relay device selected from among the neighboring device based on the result of measuring the channel quality, and to perform D2D communication with the another device via the relay device using resources allocated by the relay device when receiving a handover complete message indicating that resource allocation has been completed from the relay device.