Mobile communication system having improved visitor location register content management and method of operation

• US 6,021,327 A
• Filed: 04/15/1997
• Issued: 02/01/2000
• Est. Priority Date: 04/15/1997
• Status: Expired due to Term

• Current Assignee: Ericsson AB (Telefonaktiebolaget LM Ericsson)
• Original Assignee: Nortel Networks Corporation
• Inventors: Kolski, Stephen R., Nguyen, Nhut, Sollee, Patrick N.
• Primary Examiner(s): Chin, Wellington
• Assistant Examiner(s): Tran, Congvan
• Application Number:
  US08/842,668
• Time in Patent Office: 1,022 Days
• Field of Search: 455/433, 455/432, 455/435, 455/436, 455/439
• US Class Current: 455/433
• CPC Class Codes: H04W 8/06 Registration at serving network Location Register, VLR or user mobility server

Abstract

A wireless communication system includes at least one mobile switching center ("MSC"), at least one base station coupled to each MSC, a visitor location register ("VLR") and a visitor location register manager ("VLRM"). Each MSC couples to at least one base system controller ("BSC") which couples to at least one base transceiver station ("BTS"). Each BTS provides wireless communication within at least one respective cell, each of the plurality of mobile terminals communicating through a corresponding BTS, BSC and MSC when resident within a cell. The VLR corresponds to one of the MSCs and stores subscriber information for mobile terminals that are active in corresponding cells. The VLRM downloads, from a home location register, subscriber information for mobile terminals becoming active within one of a plurality of cells corresponding to the VLR and stores the subscriber information as a VLR record in the VLR. In accordance with the present invention, the VLRM selectively retains VLR records when corresponding mobile terminals becomes inactive within the cells corresponding to the VLR. The VLRM organizes the VLR records based upon a selected priority. In one embodiment, the VLR is organized as a linked list based upon the priority of VLR records. Stored on the basis of priority, the VLRM may delete VLR records on the same priority basis. In one embodiment of the present invention, a selected priority relates to the time stamp of last activity within any cell respective to the VLR.

Claims

1. A wireless communication system for communicating with a plurality of mobile terminals comprising:

at least one mobile switching center;

at least one base station communicatively coupled with each mobile switching center, each base station providing wireless communications within at least one respective cell, each of the plurality of mobile terminals communicating through a corresponding base station and corresponding mobile switching center when resident within a cell;

a visitor location register corresponding to one of the mobile switching centers; and

a visitor location register manager that downloads, from a home location register, subscriber information for a plurality of mobile terminals active within corresponding cells, that stores the subscriber information as visitor location register records in the visitor location register, that organizes the visitor location register records based upon a prioritization of the visitor location register records, and that periodically deletes a first plurality of visitor location register records that have a lower priority than a second plurality of visitor location records, the second plurality of visitor location records not deleted from the visitor location register.

2. The wireless communication system of claim 1, wherein older visitor location resister records are prioritized lower than newer visitor location register records and wherein an age of a visitor location register record is based upon a time since last activity of a corresponding mobile unit within an area served by the visitor location register.

3. The wireless communication system of claim 1, the visitor location register manager removing at least one visitor location register record from the visitor location register when the visitor location register becomes full.

4. The wireless communication system of claim 1, wherein the first plurality of visitor location register records are deleted to provide a predetermined number of vacancies in the visitor location register.

5. The wireless communication system of claim 4, wherein the predetermined number of vacancies is determined based upon an expected number of new subscriber records to be stored in the visitor location record over a next time period.

6. The wireless communication system of claim 1, the visitor location register manager organizing visitor location register records in the visitor location register as a linked list based upon respective priority of the visitor location register records.

7. The wireless communication system of claim 6, the visitor location register manager periodically removing visitor location register records from the visitor location register to provide a predetermined number of vacancies within the visitor location register by sequentially removing next lowest priority records from the visitor location register until a vacancy threshold is met.

8. The wireless communication system of claim 7, the visitor location register manager removing at least one visitor location register record when visitor location register contents exceed a threshold level.

9. The wireless communication system of claim 7, each visitor location register record including a pointer to a next higher priority visitor location register record and a pointer to a next lower priority visitor location register record.

10. In a wireless communication system having at least one mobile switching center, at least one base station communicatively coupled with each mobile switching center, with each base station providing wireless communications within at least one respective cell and with each of the plurality of mobile terminals communicating through a corresponding base station and a corresponding mobile switching center when resident within a cell, and a home location register, a visitor management system comprising:

a visitor location register corresponding to one of the mobile switching centers; and

a visitor location register manager that downloads, from a home location register, subscriber information for a mobile terminal active within one of a plurality of cells corresponding to the visitor location register, that stores the subscriber information as a visitor location register record in the visitor location register, that prioritizes the visitor location register record with respect to other visitor location register records stored in the visitor location register, and that periodically deletes a first plurality of visitor location register records that have a lower priority than a second plurality of visitor location records, the second plurality of visitor location records not deleted from the visitor location register.

11. The visitor management system of claim 10, wherein older visitor location register records are prioritized lower than newer visitor location resister records and wherein an age of a visitor location resister record is based upon a time since last activity of a corresponding mobile unit within an area served by the visitor location register.

12. The visitor management system of claim 10, the visitor location register manager removing at least one visitor location register record from the visitor location register when the visitor location register is full and storage of additional subscriber information is required.

13. The visitor management system of claim 10, the visitor location register manager organizing visitor location register records in the visitor location register as a linked list based upon priority of a respective mobile terminal within the plurality of cells corresponding to the visitor location register.

14. The visitor management system of claim 13, the visitor location register manager periodically removing visitor location register records from the visitor location register to provide a predetermined number of vacancies within the visitor location register by sequentially removing next oldest records from the visitor location register until a vacancy threshold is met.

15. The visitor management system of claim 13, each visitor location register record including a pointer to a next higher priority visitor location register record and a pointer to a next lower priority visitor location register record.

16. In a wireless communication system having at least one mobile switching center, at least one base station communicatively coupled with each mobile switching center with each base station providing wireless communications within at least one respective cell and with each of the plurality of mobile terminals communicating through a corresponding base station and corresponding mobile switching center when resident within a cell, a home location register and a visitor location register, a visitor management method comprising the steps of:

upon activity of a mobile terminal within a cell corresponding to the visitor location register, downloading, from a home location register, subscriber information for the mobile terminal;

storing the subscriber information as a visitor location register record in the visitor location register;

organizing visitor location register records based upon respective priorities; and

periodically deleting a first plurality of visitor location register records that have a lower priority than a second plurality of visitor location records, the second plurality of visitor location records not deleted from the visitor location register.

17. The method of claim 16, further comprising the step of:

prioritizing older visitor location register records lower than newer visitor location register records, wherein an age of a visitor location register record is based upon a time since last activity of a corresponding mobile unit within an area served by the visitor location register.

18. The method of claim 16, wherein the first plurality of visitor location register records are deleted to provide a predetermined number of vacancies in the visitor location register.

19. The method of claim 16, further comprising the step of:

removing at least one visitor location register record from the visitor location register when the visitor location register is full and storage of additional subscriber information is required.

20. The method of claim 16, further comprising the step of:

organizing visitor location register records in the visitor location register as a linked list based upon priority of respective visitor location register records.