Apparatus and method for performing an interfrequency handoff in a wireless network

• US 7,512,403 B2
• Filed: 12/20/2002
• Issued: 03/31/2009
• Est. Priority Date: 12/20/2002
• Status: Expired due to Fees

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Kodali, Sanjay Kumar, Cleveland, Joseph R., Rajkotia, Purva R.
• Primary Examiner(s): ZEWDU, MELESS NMN
• Application Number:
  US10/325,649
• Publication Number:
  US 20040121774A1
• Time in Patent Office: 2,293 Days
• Field of Search: 455/422.1, 455/435.1, 455/435.3, 455436-451, 4554561-4563, 4554565-4566, 455/455, 455524-525, 455/550.1, 455/552.1, 455/556.2, 455560-561, 370/331, 370/343
• US Class Current: 455/438
• CPC Class Codes: H04W 36/32 by location or mobility data, e.g. speed data
• CPC Class Codes: H04W 36/322 by location data
• CPC Class Codes: H04W 36/324 by mobility data, e.g. speed data

Abstract

An apparatus and method for performing an interfrequency hard handoff at a border cell in a wireless network. The apparatus comprises a handoff controller within a source base station that selects an optimal target base station using location information of at least one target base station and using one of: a location of the wireless mobile station, a velocity of the wireless mobile station, and a direction of motion of the wireless mobile station. The present invention uses the location information of at least one target base station in order to make more reliable handoff decisions.

Claims

1. For use in a source base station for communicating with a wireless mobile station in a wireless network, an apparatus for selecting at least one target base station for a handoff of said wireless mobile station, said apparatus comprising:

a base station location database, said base station location database containing location information of a plurality of base stations; and

a handoff controller for selecting said at least one target base station for an interfrequency hard handoff based on a location information of said at least one target base station contained in said base station location database and one of;

a geographic location of said wireless mobile station, a velocity of said wireless mobile station, and a direction of motion of said wireless mobile station,

wherein said handoff controller receives a message that contains base station location information, and said handoff controller selects said at least one target base station for the interfrequency hard handoff based on at least one pilot signal strength measurement received by said wireless mobile station, and

wherein said handoff controller places said base station location information from said message in said base station location database and creating, from said base station location database, a preferential order of target base stations to which to hand off said wireless mobile station.

2. The apparatus as set forth in claim 1 wherein said handoff controller comprises:

a processor within said source base station;

a memory coupled to said processor; and

a handoff decision control program within said memory, said handoff decision control program executed by said processor to select said at least one target base station for said handoff of said wireless mobile station.

3. The apparatus as set forth in claim 1 wherein said handoff controller receives said geographic location of said wireless mobile station and calculates a distance of said wireless mobile station to the at least one selected target base station.

4. The apparatus as set forth in claim 1 wherein said handoff controller receives a first geographic location of said wireless mobile station at a first time and a second geographic location of said wireless mobile station at a second time and calculating the velocity of said wireless mobile station.

5. The apparatus as set forth in claim 1 wherein said handoff controller receives a first geographic location of said wireless mobile station at a first time and a second geographic location of said wireless mobile station at a second time and calculating the direction of motion of said wireless mobile station.

6. The apparatus as set forth in claim 1 wherein said preferential ranking of said target base stations is selected by using the location information of said target base stations and using one of:

the geographic location of said wireless mobile station;

the velocity of said wireless mobile station; and

the direction of motion of said wireless mobile station.

7. A source base station comprising:

an apparatus for selecting at least one target base station for a handoff of a wireless mobile station, said apparatus comprising;

a base station geographic location database, said base station location database containing location information of a plurality of base stations; and

a handoff controller for selecting said at least one target base station for an interfrequency hard handoff based on a location information of said at least one target base station contained in said base station location database and one of;

a location of said wireless mobile station, a velocity of said wireless mobile station, and a direction of motion of said wireless mobile station,

wherein said handoff controller receives a message that contains base station location information, and said handoff controller selects said at least one target base station for the interfrequency hard handoff based on at least one pilot signal strength measurement received by said wireless mobile station; and

wherein said handoff controller places said base station location information from said message in said base station location database and creating, from said base station location database, a preferential order of target base stations to which to hard hand off said wireless mobile station.

8. The source base station as set forth in claim 7 wherein said handoff controller comprises:

a processor within said source base station;

a memory coupled to said processor; and

a handoff decision control program within said memory, said handoff decision control program executable by said processor to select said at least one target base station for said hard handoff of said wireless mobile station.

9. The source base station as set forth in claim 7 wherein said handoff controller receives said geographic location of said wireless mobile station and calculates a distance of said wireless mobile station to at least one interfrequency target base station.

10. The source base station as set forth in claim 7 wherein said handoff controller receives a first geographic location of said wireless mobile station at a first time and a second geographic location of said wireless mobile station at a second time and calculating the velocity of said wireless mobile station.

11. The source base station as set forth in claim 7 wherein said handoff controller receives a first geographic location of said wireless mobile station at a first time and a second geographic location of said wireless mobile station at a second time and calculating the direction of motion of said wireless mobile station.

12. The source base station as set forth in claim 8 wherein said preferential ranking of said target base stations is selected by using the location information of said target base stations and using one of:

the geographic location of said wireless mobile station;

the velocity of said wireless mobile station; and

the direction of motion of said wireless mobile station.

13. In a wireless network for communicating with wireless mobile stations located in a coverage area of the wireless network, a method for selecting at least one target base station for a handoff of a wireless mobile station, said method comprising the steps of:

coupling a base station location database to a handoff controller within a source base station, said base station location database containing location information of a plurality of base stations;

receiving a message within said handoff controller that contains a base station location information;

placing said base station location information from said message in said base station location database;

receiving within said handoff controller one of;

a geographic location of said wireless mobile station, a velocity of said wireless mobile station, and a direction of motion of said wireless mobile station;

selecting said at least one target base station for an interfrequency hard handoff of said wireless mobile station using said location information of the at least one selected target base station contained in said base station location database and using one of;

said geographic location of said wireless mobile station, said velocity of said wireless mobile station, and said direction of motion of said wireless mobile station, wherein the step of selecting said at least one target base station for said hard handoff of said wireless mobile station further uses at least one pilot signal strength measurement received by said wireless mobile station; and

creating, from said base station location database, a preferential order of target base stations to which to hard hand off said wireless mobile station.

14. The method as set forth in claim 13 further comprising the steps of:

receiving the geographic location of said wireless mobile station within said handoff controller; and

calculating in said handoff controller a distance of said wireless mobile station to the at least one selected target base station.

15. The method as set forth in claim 13 further comprising the steps of:

receiving within said handoff controller a first geographic location of said wireless mobile station at a first time;

receiving within said handoff controller a second geographic location of said wireless mobile station at a second time; and

calculating in said handoff controller the velocity of said wireless mobile station.

16. The method as set forth in claim 13 further comprising the steps of:

receiving within said handoff controller a first geographic location of said wireless mobile station at a first time;

receiving within said handoff controller a second geographic location of said wireless mobile station at a second time; and

calculating in said handoff controller the direction of motion of said wireless mobile station.

17. The method as set forth in claim 13 wherein said preferential ranking of said target base stations is selected by the steps of:

receiving within said handoff controller the location information of said target base stations; and

selecting said preferential ranking of said target base stations using said location information of said target base stations and using one of;

said geographic location of said wireless mobile station, said velocity of said wireless mobile station, and said direction of motion of said wireless mobile station.