Mobile communication system, base station, and base station controller

• US 6,295,451 B1
• Filed: 11/19/1998
• Issued: 09/25/2001
• Est. Priority Date: 11/21/1997
• Status: Expired due to Fees

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Mimura, Masahiko
• Primary Examiner(s): Vo, Nguyen T.
• Assistant Examiner(s): Lee, John J.
• Application Number:
  US09/195,613
• Time in Patent Office: 1,041 Days
• Field of Search: 455/436, 455/439, 455/438, 455/443, 455/453, 455/525, 455/33.1, 455/33.2, 455/56.1, 455/442, 455/437, 370/331, 370/345, 379/59
• US Class Current: 455/436
• CPC Class Codes: H04W 16/06 Hybrid resource partitioning, e.g. channel borrowing

Abstract

A control station manages available channel counts in base stations, and notifies each base station of the available channel counts. Each base station compares the priority values of the respective base stations which are obtained by adding the available channel counts notified from the control station to the pilot reception power values, in a mobile station communicating through a radio path connected to the self-station, which are related to the respective base stations. The base station then performs handoff processing to switch the radio path connected to the mobile station to the base station with the maximum priority value. With this operation, the traffic can be distributed without increasing the base station facilities and requiring complicated and cumbersome control, thereby providing stable communication services.

Claims

1. A mobile communication system in which a plurality of base stations are distributed such that a communication range of each base station overlaps communication ranges of other adjacent base stations, and handoff control for a mobile station communicating through one of said plurality of base stations is performed on the basis of reception powers in said mobile station which are related to predetermined signals output from said respective base stations, comprising:

means for selecting a base station for taking charge of said mobile station, for which the handoff control is to be performed, on the basis of priority values, the priority values being mathematical functions of reception powers in said mobile station and traffic amounts in said respective base stations, the reception powers being related to predetermined signals output from said respective base stations; and

means for performing handoff control to allow said mobile station to perform communication through said selected base station.

2. A system according to claim 1, wherein said base station selecting means selects a base station on the basis of priority values obtained by adding predetermined correction values corresponding to the traffic amounts in said respective base stations to reception power values in said mobile station for which handoff control is to be performed, the reception power values being related to the predetermined signals output from said respective base stations.

3. A system according to claim 2, wherein said base station selecting means adopts, as a priority value, a reception power value in said mobile station which is related to a predetermined signal output from a base station whose traffic amount is smaller than a predetermined value.

4. A system according to claim 1, wherein said system further comprises correction value generating means for generating a correction value that changes at delay intervals upon a change in the traffic amount in a base station, and said base station selecting means uses the correction value generated by said correction value generating means to select said base station.

5. A system according to claim 1, wherein said handoff control means is provided in each of said plurality of base stations and performs handoff control for a mobile station communicating through said base station in which said handoff control means is provided.

6. A system according to claim 5, further comprising a control station for collectively controlling said plurality of base stations, said control station comprising traffic amount notification means for notifying each of said plurality of base stations of traffic amounts in said remaining base stations.

7. A system according to claim 6, wherein said traffic amount notification means notifies each base station of the number of available traffic channels in said remaining base stations.

8. A mobile communication system in which a plurality of base stations are distributed such that a communication range of each base station overlaps communication ranges of other adjacent base stations, and handoff control for a mobile station communicating through one of said plurality of base stations is performed on the basis of reception powers in said mobile station which are related to predetermined signals output from said respective base stations, comprising:

means for selecting a base station for taking charge of said mobile station, for which the handoff control is to be performed, on the basis of reception powers in said mobile station and traffic amounts in said respective base stations, the reception powers being related to predetermined signals output from said respective base stations;

means for performing handoff control to allow said mobile station to perform communication through said selected base station; and

correction value generating means having a conversion table for converting a traffic amount in each base station into a predetermined correction value, and said base station selecting means mathematically combines the correction value generated by said correction value generating means with a reception power to select a base station.

9. A base station used in a mobile communication system in which a plurality of base stations are distributed such that a communication range of each base station overlaps communication ranges of other adjacent base stations, and handoff control for a mobile station communicating through one of said plurality of base stations is performed on the basis of reception powers in said mobile station which are related to predetermined signals output from said respective base stations, comprising:

means for selecting a base station for taking charge of said mobile station, for which the handoff control is to be performed, on the basis of priority values, the priority values being mathematical functions of reception powers in said mobile station and traffic amounts in said respective base stations, the reception powers being related to predetermined signals output from said respective base stations; and

means for performing handoff control to allow said mobile station to perform communication through said selected base station.

10. A base station according to claim 9, wherein said base station selecting means selects a base station on the basis of priority values obtained by adding predetermined correction values corresponding to the traffic amounts in said respective base stations to reception power values in said mobile station for which handoff control is to be performed, the reception power values being related to the predetermined signals output from said respective base stations.

11. A base station according to claim 9, wherein said base station selecting means adopts, as a priority value, a reception power value in said mobile station which is related to a predetermined signal output from a base station whose traffic amount is smaller than a predetermined value.

12. A base station according to claim 9, wherein said system further comprises correction value generating means for generating a correction value that changes delay intervals upon a change in the traffic amount in a base station, and said base station selecting means uses the correction value generated by said correction value generating means to select said base station.

13. A base station used in a mobile communication system in which a plurality of base stations are distributed such that a communication range of each base station overlaps communication ranges of other adjacent base stations, and handoff control for a mobile station communicating through one of said plurality of base stations is performed on the basis of reception powers in said mobile station which are related to predetermined signals output from said respective base stations, comprising:

means for selecting a base station for taking charge of said mobile station, for which the handoff control is to be performed, on the basis of reception powers in said mobile station and traffic amounts in said respective base stations, the reception powers being related to predetermined signals output from said respective base stations;

means for performing handoff control to allow said mobile station to perform communication through said selected base station; and

correction value generating means having a conversion table for converting a traffic amount in each base station into a predetermined correction value, and said base station selecting means mathematically combines the correction value generated by said correction value generating means with a reception power to select a base station.

14. A base station controller used in a control station for collectively controlling a plurality of base stations in a mobile communication system in which said plurality of base stations are distributed such that a communication range of each base station overlaps communication ranges of other adjacent base stations, and handoff control for a mobile station communicating through one of said plurality of base stations is performed on the basis of reception powers in said mobile station which are related to predetermined signals output from said respective base stations, said base station controller comprising:

means for managing traffic amounts in said respective base stations; and

traffic amount notification means for, in response to a request from any one of said plurality of base stations, notifying said base station as a request source of the traffic amounts in said remaining base stations, the traffic amounts being used with the reception powers to determine a base station that should take charge of said mobile station for which the handoff control is to be performed.

15. A base station controller according to claim 14, wherein said traffic amount managing means manages the number of available traffic channels in each base station.

16. A base station controller according to claim 14, wherein said traffic amount notification means notifies said base station of the number of available traffic channels in said remaining base stations.

17. In a mobile communication system having a plurality of base stations, wherein a coverage area of each base station overlaps a coverage area of other base stations, a method for controlling handoff of a communication involving a mobile station communicating through one of the plurality of base stations, said method comprising the step of:

determining whether to handoff a communication involving a mobile station being handled by a base station to another base station based on received power signals in said mobile station related to predetermined signals output by base stations other than the base station handling the communication and an amount of communication traffic being handled by each other base station; and

selecting one of the other base stations to handoff the communication to based on priority values, the priority values being a function of the received power signals and the amount of communication traffic being handled by each other base station.

18. The method of claim 17 further comprising the step of notifying the base station handling the communication of the amount of communication traffic being handled by the other base stations.

19. The method of claim 18 wherein said step of notifying further includes notifying the base station handling the communication of the number of available traffic channels in other base stations.

20. In a mobile communication system having a plurality of base stations, wherein a coverage area of each base station overlaps a coverage area of other base stations, a base station handling a communication involving a mobile station, said base station comprising:

a receiver configured to receive information regarding power signals received by said mobile station related to predetermined signals output from the base station handling the communication and other base stations and an amount of communication traffic being handled by each of the other base stations; and

a processor configured to generate first and second priority values, a first priority value being a mathematical function of the information received regarding power signals and the amount of communication traffic being handled by a first other base station, the second priority value being a function of the power signal of said base station handling the communication and the amount of communication traffic being handled by said base station handling the communication, and said processor configured to determine whether to handoff the communication involving said mobile station to the first other base station based on the first and second priority values.

21. The base station of claim 20, wherein the amount of communication traffic being handled by each other base station is the number of available channels in the other base station.

22. The base station of claim 20, wherein said processor is configured to generate a third priority value, the third priority value being a mathematical function of the information regarding power signals and the amount of communication traffic being handled by a second other base station, said processor configured to determine whether to handoff the communication involving said mobile station to the first other base station based on the first, second and third priority values.