METHOD FOR HANDOVER FROM HOME CELL TO PUBLIC CELL IN MOBILE COMMUNICATION SYSTEM

• US 20100309887A1
• Filed: 11/26/2008
• Published: 12/09/2010
• Est. Priority Date: 11/28/2007
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Kim, Hye-Jeong, Joo, Yang-Ick
• Granted Patent: US 9,313,699 B2
• Time in Patent Office: Days
• US Class Current: 370/332
• CPC Class Codes: H04W 36/0077 of access information of target access point
• CPC Class Codes: H04W 36/0079 in case of hand-off failure or rejection
• CPC Class Codes: H04W 36/302 due to low signal strength
• CPC Class Codes: H04W 84/045 using private Base Stations, e.g. femto Base Stations, home Node B

Abstract

A method for a connection mode terminal to hand over between a home cell and a public cell in a mobile communication system is provided. In the mobile communication system including the home cell and the public cell, a region of the terminal is determined and a random access channel for the handover is pre-allocated. When the normal handover from the home cell to the public cell fails, the access to the public cell is accomplished using the pre-allocated random access channel. Therefore, the handover failure rate can be lowered.

Claims

1. A method for a terminal to determine a region in a mobile communication system which comprises a home cell and a public cell, the method comprising:

measuring a home cell signal and public cell signals during a measurement period;

setting a public cell having the greatest signal among signals measured in the public cells, as a max cell;

determining that the terminal locates in a first region when the measured home cell signal is greater than a first threshold (a threshold 1) and greater than the max cell signal by more than a third threshold (a threshold 2); and

determining that the terminal locates in a second region when the measured home cell signal is less than the first threshold (the threshold 1) and the max cell signal is greater than a second threshold (a threshold 3).

2. The method of claim 1, further comprising:

determining that the terminal locates in the second region when the received home cell signal is greater than the first threshold (the threshold 1) and a difference of the max cell signal and the home cell signal is less than the third threshold (the threshold 2).

3. The method of claim 1, further comprising:

setting the measurement period to a second period when determining that the terminal travels in the first region.

4. The method of claim 1, further comprising:

setting the measurement period to a third period when determining that the terminal locates in the second region.

5. The method of claim 1, further comprising:

setting the measurement period to a fourth period when the measured max cell signal is less than the second threshold (the threshold 3) and the measured home cell signal is less than the first threshold (the threshold 1).

6. The method of claim 1, further comprising:

determining a current state is a radio link failure when the measured home cell signal is less than the second threshold (the threshold 3) over a certain time.

7. The method of claim 1, wherein the determining of the first region denotes that the terminal locates in a region where the home cell is dominant.

8. The method of claim 1, wherein the determining of the second region denotes that the terminal locates in an overlapping region of the home cell and the public cell.

9. A method for setting a Random Access Channel (RACH) in a mobile communication system which comprises a home cell and a public cell, the method comprising:

checking a change of a region of a terminal;

determining whether the terminal travels in an overlapping region and whether a max public cell is changed, and releasing an RACH channel to a previous max public cell when the max public cell is changed;

releasing an RACH channel to the max public cell when the terminal travels in a home cell dominant region; and

requesting an RACH setup to the max public cell when the terminal is in the overlapping region, not in the home cell dominant region, and the RACH of the max public cell is not set.

10. An apparatus for setting a Random Access Channel (RACH) in a mobile communication system which comprises a home cell and a public cell, the apparatus comprising:

means for checking a change of a region of a terminal;

means for determining whether the terminal travels in an overlapping region and whether a max public cell is changed, and releasing an RACH channel to a previous max public cell when the max public cell is changed;

means for releasing an RACH channel to the max public cell when the terminal travels in a home cell dominant region; and

means for requesting an RACH setup to the max public cell when the terminal is in the overlapping region, not in the home cell dominant region, and the RACH of the max public cell is not set.