Cellular communicating network and method for locating mobile stations using hierarchically arranged databases

• US 6,370,378 B1
• Filed: 06/28/1999
• Issued: 04/09/2002
• Est. Priority Date: 06/29/1998
• Status: Expired due to Fees

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Yahagi, Masahiko
• Primary Examiner(s): Nguyen, Lee
• Assistant Examiner(s): Le, Danh C
• Application Number:
  US09/340,023
• Time in Patent Office: 1,016 Days
• Field of Search: 455/433, 455/432, 455/435, 455/458, 455/500, 370/337
• US Class Current: 455/433
• CPC Class Codes: G01S 2205/008 using a mobile telephone network
• CPC Class Codes: G01S 5/0027 of actual mobile position, i.e. position determined on mobile

Abstract

In a cellular mobile communication network, mobile records are maintained in a first database for indicating a base station area when a mobile station crosses a boundary between adjacent location areas and enters that base station area. A second database is associated with each control group of base station areas for maintaining mobile records for indicating a base station area when the mobile station successively crosses a boundary between adjacent base station areas. In response to a call request, one of the mobile records of the first database is accessed to identify a control group of base station areas and a search request is produced. In response to the search request, one of the mobile records of the second database is accessed and a paging signal is broadcast to at least one base station area indicated in the accessed mobile record to wait for a response from the mobile station. If no response is not returned, the paging signal is broadcast to remaining base station areas of the identified control group.

Claims

1. A cellular mobile communication network including a plurality of base stations for respectively covering base station areas, the base station areas being assembled into a plurality of location areas and the base station areas of each location area being assembled into a plurality of control groups, the network comprising:

a first database for maintaining a plurality of mobile records, each of the mobile records indicating one of said base station areas when a mobile station crosses a boundary between adjacent location areas and enters said one base station area;

a second database associated with one of said control groups of base station areas for maintaining a plurality of mobile records, one of the mobile records indicating a base station area when said mobile station successively crosses a boundary between adjacent base station areas of one of said location areas;

a first controller responsive to a call request for accessing one of the mobile records in said first database to identify one of said control groups of base station areas and producing a search request; and

a second controller associated with one of said control groups of base station areas, the second controller being responsive to said search request for accessing one of said mobile records of said second database and transmitting a paging signal to at least one base station area indicated in the accessed mobile record to wait for a response from said mobile station and broadcasting the paging signal to remaining base station areas of said identified control group if said response is not returned from said mobile station.

2. The cellular mobile communication network of claim 1, wherein said mobile station is arranged to transmit a message indicating that the mobile station is crossing the boundary between adjacent location areas, and wherein said first controller is arranged to respond to the message for creating said one mobile record in said first database and returning an acknowledgment message to said mobile station.

3. The cellular mobile communication network of claim 2, wherein said mobile station is arranged to transmit a message indicating that the mobile station is crossing the boundary between adjacent base station areas, and wherein said second controller is arranged to respond to the message for creating said one mobile record in said second database and returning no acknowledgment message to said mobile station.

4. The cellular mobile communication network of claim 1, wherein said second controller is arranged to:

identify a base station area indicated by most recently stored data in the accessed mobile record;

transmit said paging signal to the identified base station area to determine whether a response is returned from the identified base station area;

if no response is returned, identify other base station areas indicated by data stored in the accessed mobile record;

transmit said paging signal to the identified other base station areas to determine whether a response is returned from one of the identified other base station areas; and

if no response is returned, broadcast the paging signal to remaining base station areas of said identified group of base station areas.

5. The cellular mobile communication network of claim 1, further comprising a geographic database for storing geographic data for said identified control group of base station areas, wherein said second controller is arranged to:

select at least one base station area which is recently stored in said one mobile record of said second database;

broadcast said paging signal to the selected at least one base station area and wait for a response;

if no response is returned, evaluate said one mobile record of said second database using said geographic database to determine at least one base station area; and

broadcast said paging signal to the determined at least one base station area and wait for a response from said mobile station.

6. The cellular mobile communication network of claim 1, wherein said first controller is provided in a mobile switching center and said second controller is provided in a base station controller.

7. The network of claim 1, wherein said mobile station is not simultaneously paged from more than one base station.

8. The network of claim 1, further comprising a location memory, coupled to said second controller, that stores information on a location of said mobile station.

9. A communication method for a cellular mobile communication network including a plurality of base stations for respectively covering base station areas, the base station areas being assembled into a plurality of location areas and the base station areas of each location area being assembled into a plurality of control groups, the method comprising the steps of:

a) maintaining a plurality of mobile records in a first database (111), each of the mobile records indicating one of said base station areas when a mobile station crosses a boundary between adjacent location areas and enters said one base station area;

b) maintaining a plurality of mobile records in a second database associated with one of said control groups of base station areas, one of the mobile records indicating a base station area when said mobile station successively crosses a boundary between adjacent base station areas of one of said location areas;

c) accessing one of the mobile records in said first database in response to a call request and identifying one of said control groups of base station areas and producing a search request;

d) accessing one of said mobile records of said second database in response to said search request;

e) broadcasting a paging signal to at least one base station area indicated in the accessed mobile record to wait for a response from said mobile station; and

f) broadcasting the paging signal to remaining base station areas of said identified control group if said response is not returned from said mobile station.

10. The method of claim 9, wherein said mobile station is arranged to transmit a message indicating that the mobile station is crossing the boundary between adjacent location areas, and wherein the step (a) comprises the steps of:

responsive to the message from the mobile station, creating said one mobile record in said first database; and

returning an acknowledgment message to said mobile station.

11. The method of claim 10, wherein said mobile station is arranged to transmit a message indicating that the mobile station is crossing the boundary between adjacent base station areas, and wherein the step (b) comprises the steps of:

responsive to the message from the mobile station,

creating said one mobile record in said second database and returning no acknowledgment message to said mobile station.

12. The method of claim 9, wherein the step (e) comprises the steps of:

identifying a base station area indicated by most recently stored data in the accessed mobile record;

transmitting said paging signal to the identified base station area to determine whether a response is returned from the identified base station area;

if no response is returned, identifying other base station areas indicated by data stored in the accessed mobile record;

transmitting said paging signal to the identified other base station areas to determine whether a response is returned from one of the identified other base station areas; and

if no response is returned, broadcasting the paging signal to remaining base station areas of said identified group of base station areas.

13. The method of claim 9, further comprising a geographic database for storing geographic data for said identified control group of base station areas, wherein the step (e) comprises the steps of:

selecting at least one base station area which is recently stored in said one mobile record of said second database;

broadcasting said paging signal to the selected at least one base station area and waiting for a response from said mobile station;

if said response is not returned from said mobile station, evaluating said one mobile record of said second database using said geographic database to determine at least one base station area; and

broadcasting said paging signal to the determined at least one base station area and waiting for a response from said mobile station.

14. The method of claim 9, wherein simultaneous paging between said mobile station and more than one base station does not occur.

15. The method of claim 9, further comprising storing location information of said mobile station in a location memory that is coupled to said second controller.

16. A cellular mobile communication network, comprising:

a plurality of base stations that cover respective base station areas, said base station areas being assembled into a plurality of location areas, wherein said base station areas of each location area are assembled into a plurality of control groups;

a first database that maintains a plurality of mobile records indicative of one of said base station areas, when a mobile station crosses a boundary between adjacent location areas and enters said one base station area;

a second database that is associated with only one of said control groups of base station areas to maintain a plurality of mobile records, one of said mobile records being indicative of a base station area when said mobile station successively crosses a boundary between adjacent base station areas of one of said location areas;

a first controller configured to respond to a call request and access one of said mobile records in said first database to identify one of said control groups of base station areas and produce a search request;

a second controller associated with only one of said control groups of base station areas, the second controller being responsive to said search request to access one of said mobile records of said second database, and to transmit a paging signal to at least one base station area indicated in said access mobile record to wait for a response from said mobile station and to broadcast said paging signal to remaining base station areas of said identified control group if said response is not returned from said mobile station; and

a geographic database that stores geographic data for said identified control group of base station areas.

17. The network of claim 16, wherein said second controller is configured to select at least one base station area that is recently stored in said one mobile record of said second database, broadcast said paging signal to said selected at least one base station area and await a response, evaluate said one mobile record of said second database using said geographic database to determine at least one base station area, and broadcast said paging signal to said determined at least one base station are and wait for a response form said mobile station.

18. The network of claim 16, wherein said first controller is provided in a mobile switching center and said second controller is provided in a base station controller.

19. The network of claim 16, wherein said mobile station transmits a message indicative of said mobile station crossing a boundary between adjacent location areas, and said first controller responds to said message to create said one mobile record in said first database and returns an acknowledgement message to said mobile station.

20. The network of claim 19, wherein said mobile station transmits a message indicative of said mobile station crossing a boundary between adjacent base station areas, and wherein said second controller responds to said message to create said one mobile record in said second database and returns no acknowledgement message to said mobile station.