Tracking mobile users in wireless networks

• US 5,524,136 A
• Filed: 04/20/1992
• Issued: 06/04/1996
• Est. Priority Date: 04/20/1992
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Kessler, Ilan, Bar-Noy, Amotz
• Primary Examiner(s): Chin, Stephen
• Assistant Examiner(s): Shankar, Vijay
• Application Number:
  US07/871,252
• Time in Patent Office: 1,506 Days
• Field of Search: 379/58, 379/59, 379/60, 455/33.1, 455/33.2, 455/33.4, 455/54.1, 455/54.2, 455/56.1
• US Class Current: 455/456.1
• CPC Class Codes: H04W 60/04 using triggered events
• CPC Class Codes: H04W 68/04 multi-step notification using statistical or historical mobility data

Abstract

A method and apparatus for efficiently tracking the location of a mobile station in a cellular network, especially in cellular networks having nonuniform traffic distribution. A mobile station reports to a base station only upon entering selected reporting cells. When communication with a mobile station is desired, the station is searched for in the vicinity of the last reporting cell in which the station appeared. The vicinity of a reporting cell is defined as the set of all intersecting cells reachable from the reporting cell without passing through another reporting cell.

Claims

1. A method of tracking mobile users of a cellular network, comprising the steps of:

a. designating independently of any mobile user movements within cellular network a number of cells of said cellular network to be reporting cells and all other cells to be non-reporting cells, said number of reporting cells being less than the total number of cells of said cellular network;

b. sending a reporting signal from each of said mobile users only when said each of said mobile users enters one of said reporting cells, each said reporting signal identifying a location of a corresponding one of said mobile users; and

c. searching for a mobile user only in the vicinity of the last corresponding reporting cell from which said mobile user sent a reporting signal, said searching being conducted when communication is desired with said mobile user, where the vicinity of said last corresponding reporting cell is the set of cells consisting of said last corresponding reporting cell and all non-reporting cells that are reachable by intercellular transitions of said mobile user travelling from said last corresponding reporting cell without having to enter any other reporting cell.

2. An apparatus for tracking mobile users of a cellular network, comprising:

a. means for designating independently of any mobile user movements within the cellular network a number of cells of said cellular network to be reporting cells and all other cells of said cellular network to be non-reporting cells, said number of reporting cells being less than the total number of cells of said cellular network;

b. means for sending a reporting signal from each of said mobile users only when said each of said mobile users enters one of said reporting cells, each said reporting signal identifying a location of a corresponding one of said mobile users; and

c. means for searching for a mobile user only in the vicinity of the last corresponding reporting cell from which said mobile user sent a reporting signal, said searching being conducted when communication is desired with said mobile user, where the vicinity of said last corresponding reporting cell is the set of cells consisting of said last corresponding reporting cell and all non-reporting cells that are reachable by intercellular transitions of said mobile user travelling from said last corresponding reporting cell without having to enter any other reporting cell.

3. An apparatus for tracking inactive mobile users within a cellular network of cells without requiring each inactive mobile user to report whenever moving from one cell to another cell in the cellular network and without requiring a search of the whole cellular network when a message needs to be delivered from the cellular network to an inactive mobile user, comprising:

means for designating a number of the cells of said cellular network to be reporting cells and all other cells of said cellular network to be non-reporting cells, said number of reporting cells being less than the total number of cells of said cellular network;

means for sending a reporting signal to the cellular network from each of said inactive mobile users whenever and only whenever each said inactive mobile user enters one of said reporting cells, said reporting signal identifying said reporting cell entered by said each inactive mobile user as a most recent reporting cell corresponding to said each inactive mobile user; and

means for searching for a desired inactive mobile user when a message needs to be sent to said desired inactive mobile user by searching for said desired inactive mobile user only in a vicinity of said most recent reporting cell corresponding to said desired inactive mobile user, said vicinity of said most recent reporting cell being a set of cells consisting of said most recent reporting cell corresponding to said desired inactive mobile user and all non-reporting cells that are reachable by a sequence of intercellular transitions from said most recent reporting cell corresponding to said desired inactive mobile user without entering any other reporting cell.

4. An apparatus as defined in claim 3 wherein said means for designating a number of the cells of said cellular network to be reporting cells includes means for periodically transmitting a message from each said reporting cell identifying said each reporting cell as a reporting cell.

5. An apparatus as defined in claim 4 wherein said means for sending a reporting signal to the cellular network from each of said inactive mobile users comprises means for each said inactive mobile user to receive said periodically transmitted message from any reporting cell entered by said each inactive mobile user and for transmitting a reporting signal whenever and only whenever said message received by said each inactive mobile user identifies a reporting cell different from said most recent reporting cell corresponding to said each inactive mobile user.

6. A method for tracking inactive mobile users within a cellular network of cells without requiring each inactive mobile user to report whenever moving from one cell to another cell in the cellular network and without requiring a search of the whole cellular network when a message needs to be delivered from the cellular network to an inactive mobile user, comprising the steps of:

designating a number of the cells of said cellular network to be reporting cells and all other cells of said cellular network to be non-reporting cells, said number of reporting cells being less than the total number of cells of said cellular network;

sending a reporting signal to the cellular network from each of said inactive mobile users whenever and only whenever each said inactive mobile user enters one of said reporting cells, said reporting signal identifying said reporting cell entered by said each inactive mobile user as a most recent reporting cell corresponding to said each inactive mobile user; and

searching for a desired inactive mobile user when a message needs to be sent to said desired inactive mobile user by searching for said desired inactive mobile user only in a vicinity of said most recent reporting cell corresponding to said desired inactive mobile user, said vicinity of said most recent reporting cell being a set of cells consisting of said most recent reporting cell corresponding to said desired inactive mobile user and all non-reporting cells that are reachable by a sequence of intercellular transitions from said most recent reporting cell corresponding to said desired inactive mobile user without entering any other reporting cell.

7. A method as defined in claim 6 wherein said step of designating a number of the cells of said cellular network to be reporting cells includes the step of periodically transmitting a message from each said reporting cell identifying said each reporting cell as a reporting cell.

8. A method as defined in claim 7 wherein said step of sending a reporting signal to the cellular network from each of said inactive mobile users includes the steps of:

receiving by each said inactive mobile user said periodically transmitted message from any reporting cell entered by said each inactive mobile user; and

transmitting a reporting signal whenever and only whenever said message received by said each inactive mobile user identifies a reporting cell different from said most recent reporting cell corresponding to said each inactive mobile user.