Handover control method, wireless communication terminal, and wireless communication device

Patent metadata

Field	Value
Publication number	US-9591545-B2
Application number	US-201214131873-A
Country	US
Kind code	B2
Filing date	Jul 31, 2012
Priority date	Aug 12, 2011
Publication date	Mar 7, 2017
Grant date	Mar 7, 2017

Abstract

Under a handover control method, a wireless communication terminal receives a conditional handover command that is transmitted from a wireless communication device which provides an own cell connected to the wireless communication terminal and that gives a command to start handover to an adjacent cell when a predetermined condition is satisfied; determines whether or not the predetermined condition is satisfied; and starts handover to the adjacent cell indicated by the conditional handover command when the predetermined condition is satisfied.

First claim

The invention claimed is:

1. A handover control method that is carried out by a wireless communication terminal which performs a communication with a wireless communication device by use of a control channel and a data channel, the method comprising:
receiving a cell-specific reference signal transmitted from the wireless communication device on a per-cell basis;
based on the cell-specific reference signal, generating a measurement result report that differentiates between a control channel signal reception quality of an own cell provided by the wireless communication device connected to the wireless communication terminal and a data channel signal reception quality of the own cell;
transmitting the measurement result report to the wireless communication device that provides the own cell for determining performance of a conditional handover and a target for handover;
receiving a conditional handover command that has been transmitted from the wireless communication device which provides the own cell based on the measurement result report and that gives a command to start handover to an adjacent cell when a predetermined condition is satisfied;
determining whether or not the predetermined condition is satisfied by comparing the data channel signal reception quality of the own cell with a data channel signal reception quality of the adjacent cell; and
starting handover to the adjacent cell indicated by the conditional handover command when the predetermined condition is satisfied.

2. The handover control method according to claim 1 , wherein the predetermined condition is that the data channel signal reception quality of the adjacent cell measured by the wireless communication terminal is superior to the data channel signal reception quality of the own cell measured by the wireless communication terminal.

3. The handover control method according to claim 1 , wherein the predetermined condition is that the control channel signal reception quality of the own cell measured by the wireless communication terminal is lower than a predetermined threshold value.

4. The handover control method according to claim 1 , wherein the predetermined condition is that the data channel signal reception quality of the adjacent cell measured by the wireless communication terminal is superior to the data channel signal reception quality of the own cell measured by the wireless communication terminal or that the control channel signal reception quality of the own cell is lower than a predetermined threshold value.

5. The handover control method according to claim 2 , wherein the predetermined condition selectively includes a case where a time which has elapsed since the conditional handover command was received reaches a limit time indicated by the conditional handover command.

6. The handover control method according to claim 1 , wherein the own cell is provided by a plurality of wireless communication devices.

7. The handover control method according to claim 1 , wherein
the own cell is provided by a plurality of wireless communication devices;
the wireless communication terminal is connected to a wireless communication device which configures a small cell among the plurality of wireless communication devices; and
the adjacent cell is a macrocell that is larger than the small cell in terms of a coverage area.

8. The handover control method according to claim 1 , wherein antennas provided in the wireless communication device that provides the own cell are larger in number than antennas provided in a wireless communication device that provides the adjacent cell.

9. The handover control method according to claim 1 , wherein a message showing that handover to the adjacent cell is started is transmitted to the wireless communication device that provides the own cell when the predetermined condition is satisfied.

10. The handover control method according to claim 1 , wherein, when a message which gives a command to start handover is received from the wireless communication device that provides the own cell before the predetermined condition is satisfied, handover to the adjacent cell indicated by the conditional handover command is started.

11. The handover control method according to claim 1 , further comprising:
receiving a new conditional handover command that indicates a condition which differs from the predetermined condition or handover to a different adjacent cell;
determining whether or not a condition indicated by the new conditional handover command is satisfied; and
starting handover to the adjacent cell indicated by the new conditional handover command when the condition indicated by the new conditional handover command is satisfied.

12. A wireless communication terminal that performs a communication with a wireless communication device by use of a control channel and a data channel, the wireless communication terminal comprising one or more integrated circuits configured to:
receive a cell-specific reference signal transmitted from the wireless communication device on a per-cell basis;
based on the cell-specific reference signal, generate a measurement result report that differentiates between a control channel signal reception quality of an own cell provided by the wireless communication device connected to the wireless communication terminal and a data channel signal reception quality of the own cell;
transmit the measurement result report to the wireless communication device that provides the own cell for determining performance of a conditional handover and a target for handover;
receive a conditional handover command transmitted from the wireless communication device which provides the own cell based on the measurement result report and that gives a command to start handover to an adjacent cell when a predetermined condition is satisfied;
determine whether or not the predetermined condition is satisfied by comparing the data channel signal reception quality of the own cell with a data channel signal reception quality of the adjacent cell; and
start handover to the adjacent cell indicated by the conditional handover command when the predetermined condition is satisfied.

13. The wireless communication terminal according to claim 12 , wherein the predetermined condition is that the data channel signal reception quality of the adjacent cell measured by the wireless communication terminal is superior to the data channel signal reception quality of the own cell measured by the wireless communication terminal.

14. The wireless communication terminal according to claim 12 , wherein the predetermined condition is that the control channel signal reception quality of the own cell measured by the wireless communication terminal is lower than a predetermined threshold value.

15. The wireless communication terminal according to claim 12 , wherein the predetermined condition is that the data channel signal reception quality of the adjacent cell measured by the wireless communication terminal is superior to the data channel signal reception quality of the own cell measured by the wireless communication terminal or that the control channel signal reception quality of the own cell is lower than a predetermined threshold value.

16. The wireless communication terminal according to claim 13 , wherein the predetermined condition selectively includes a case where a time which has elapsed since the conditional handover command was received reaches a limit time indicated by the conditional handover command.

17. The wireless communication terminal according to claim 12 , wherein the own cell is provided

Assignees

• Tamura Takashi
• Matsuo Hidenori
• Nishio Akihiko
• Imamura Daichi
• Panasonic Ip Corp America

Inventors

• Tamura Takashi
• Matsuo Hidenori
• Nishio Akihiko
• Imamura Daichi

Classifications

• H04W36/38

  by fixed network equipment · CPC title

• H04W36/04

  Reselecting a cell layer in multi-layered cells · CPC title

• H04W36/30 Primary

  by measured or perceived connection quality data · CPC title

• H04W36/0016

  Hand-off preparation specially adapted for end-to-end data sessions · CPC title

• H04W36/36

  by user or terminal equipment · CPC title