Method for performing handover based compressed mode and common frequency of neighbor cells

• US 20040053615A1
• Filed: 07/09/2003
• Published: 03/18/2004
• Est. Priority Date: 01/10/2001
• Status: Active Grant

• Current Assignee: Electronics and Telecommunications Research Institute
• Original Assignee: Electronics and Telecommunications Research Institute
• Inventors: Bang, Seung-Chan, Kim, Jae-Heung, Kim, Chang-Joo, Kim, Il-Gyu
• Granted Patent: US 7,190,944 B2
• Time in Patent Office: Days
• US Class Current: 455/436
• CPC Class Codes: H04W 36/06 Reselecting a communication resource in the serving access point
• CPC Class Codes: H04W 36/18 for allowing seamless reselection, e.g. soft reselection
• CPC Class Codes: H04W 36/302 due to low signal strength

Abstract

A method for performing a handover based on a compressed mode and a common frequency of neighbor cells is disclosed. The method for performing a handover includes the steps of: a) measuring the signal intensities of a common frequency of a source base station and a target base station, wherein the signal intensity is measured by the mobile station based on a downlink compressed mode; b) determining whether a handover is necessary or not, based on the signal intensities of the common frequency; c) if the handover is necessary, at the source base station, allowing the mobile station to perform intra cell hard handover from a frequency used for communication between the mobile station and the source base station to the common frequency; and then d) allowing the mobile station to perform a soft handover from the source base station to the target base station based on the common frequency.

Claims

1. A method for performing a handover based on a compressed mode and a common frequency of neighbor base stations in a wireless communication system, comprising the steps of:

a) receiving signal intensities of a common frequency of a source base station and a target base station, wherein the signal intensity is measured by a mobile station based on a downlink compressed mode;

b) determining whether a handover condition is satisfied based on the signal intensities;

c) if the handover condition is satisfied, invoking the mobile station to perform an intra cell hard handover from a frequency, which is currently established communication link to the common frequency of the source base station and the target base station; and

d) invoking the mobile station to perform a soft handover between the source base station to the target base station by using the common frequency of the source base station and the target base station.

2. The method as recited in claim 1, further comprising a step of:

e) after completing the hard handover, receiving frame offset information calculated based on a system frame number (SFN) of the target base station, wherein the SFN is acquired through the common frequency of the source base station and the target base station.

3. The method as recited in claim 1, wherein the data used for the hard handover includes a plurality of frames, last frame of the frequency of currently established communication link between the mobile station and the source base station, and a first frame of the common frequency are compressed mode frames, there is a guard time between the two compressed mode frames.

4. A method for a handover by using a compressed mode implemented in a wireless communication system and a common frequency between neighbor stations, comprising the steps of:

a) at a mobile station, measuring signal intensities of a common frequency of a target base station and a source base station based on a downlink compressed mode and reporting the signal intensities to a controller of a base station;

b) according to a hard handover invocation received from the base station controller, performing an intra cell hard handover from a frequency of currently established communication link to the common frequency of the source base station and the target base station; and

c) performing a soft handover between the source base station and the target base station by using the common frequency of the source base station and the target base station.

5. The method as recited in claim 4, further comprising the step of:

d) after completing the hard handover, reporting a frame offset information to the base station controller, wherein the frame offset information calculated by using a system frame number (SFN) of the target base station, and the SFN is acquired through the common frequency of the source base station and the target base station.

6. The method as recited in claim 4, wherein data used for the hard handover includes a plurality of frames, last frame of the frequency of currently established communication link between the mobile station and the source base station, and a first frame of the common frequency are compressed mode frames, there is a guard time between the two compressed mode frames.

7. A computer readable record medium storing instructions for executing the method for performing a handover based on a compressed mode and a common frequency between neighbor base stations, comprising functions of:

a) receiving signal intensities of a common frequency of a source base station and a target base station, wherein the signal intensity is measured by a mobile station based on a downlink compressed mode;

b) determining whether a handover condition is satisfied based on the signal intensities;

c) if the handover condition is satisfied, invoking the mobile station to perform an intra cell hard handover from a frequency, which is currently established communication link to the common frequency of the source base station and the target base station; and

d) invoking the mobile station to perform a soft handover between the source base station to the target base station by using the common frequency of the source base station and the target base station.

8. A computer readable record medium storing instructions for executing the method for executing the method for performing a handover based on a compressed mode and a common frequency between neighbor base stations, comprising functions of:

a) at a mobile station, measuring signal intensities of a common frequency of a target base station and a source base station based on a downlink compressed mode and reporting the signal intensities to a controller of a base station;

b) according to a hard handover invocation received from the base station controller, performing an intra cell hard handover from a frequency of currently established communication link to the common frequency of the source base station and the target base station; and

c) performing a soft handover between the source base station and the target base station by using the common frequency of the source base station and the target base station.