Handover control method, mobile station and communication control apparatus

• US 20020119779A1
• Filed: 02/01/2002
• Published: 08/29/2002
• Est. Priority Date: 02/01/2001
• Status: Active Grant

• Current Assignee: NTT Docomo Incorporated (Nippon Telegraph and Telephone Corporation)
• Original Assignee: NTT Docomo Incorporated (Nippon Telegraph and Telephone Corporation)
• Inventors: Iwamura, Mikio, Ofuji, Yoshiaki, Nakamura, Takehiro, Onoe, Seizo, Hayashi, Takahiro, Ishikawa, Yoshihiro
• Granted Patent: US 7,194,266 B2
• Time in Patent Office: Days
• US Class Current: 455/437
• CPC Class Codes: H04W 36/302 due to low signal strength
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

When a handover standby threshold falls below a received power of perch channel from a base station 150-1 of a communication partner, a mobile station 110 sends a handover standby operation request to a base station control apparatus 130, and notifies of history of movement of itself and receives powers of perch channels from base stations 150-2 -150-4 surrounding the communication partner (mobile station information). The base station control apparatus 130 compares the mobile station information with history of mobile station information so that a handover destination candidate base station is selected and sent to the mobile station 110. The mobile station 110 switches the communication partner to the handover destination candidate base station when received power of the perch channel from the base station 150-1 falls below a handover threshold.

Claims

1. A handover control method used in a mobile communication system which includes communication apparatuses having functions of base stations, a mobile station and a communication control apparatus which controls connections between said communication apparatuses and said mobile station, said handover control method comprising the steps of:

said mobile station switching a communication apparatus of a communication partner to another communication apparatus when a communication quality value between said communication apparatus of said communication partner and said mobile station falls below a first threshold which is better than a limitation value by which communication is available;

wherein said communication control apparatus selects at least a handover destination candidate communication apparatus from among communication apparatuses surrounding said communication apparatus of said communication partner when said communication quality value falls below a second threshold which is better than said first threshold; and

said communication control apparatus keeps wireless resources of said at least a handover destination candidate communication apparatus which is selected.

2. The handover control method as claimed in claim 1, comprising the steps of:

said communication control apparatus notifying said mobile station of a handover destination candidate communication apparatus for which wireless resources are kept in said at least a handover destination candidate communication apparatus; and

said mobile station switching said communication apparatus of said communication partner to said handover destination candidate communication apparatus which is notified by said communication control apparatus when said communication quality value falls below said first threshold.

3. The handover control method as claimed in claim 1, comprising the steps of:

said mobile station judging whether said communication quality value falls below said second threshold, and sending a request for selecting said at least a handover destination candidate communication apparatus to said communication control apparatus when said communication quality value falls below said second threshold.

4. The handover control method as claimed in claim 1, comprising the steps of:

when said communication control apparatus selects a plurality of handover destination candidate communication apparatuses, said communication control apparatus determining priorities of said plurality of handover destination candidate communication apparatuses;

said communication control apparatus notifying said mobile station of handover destination candidate communication apparatuses in said plurality of handover destination candidate communication apparatuses for which wireless resources are kept and corresponding priorities;

said mobile station switching said communication apparatus of said communication partner to one of said notified handover destination candidate communication apparatuses according to said priorities.

5. The handover control method as claimed in claim 1, comprising the steps of:

said mobile station sending mobile station information to said communication control apparatus, said mobile station information including a history of movement of said mobile station and received powers of perch channels from communication apparatuses surrounding said communication apparatus of said communication partner;

said communication control apparatus having a history of mobile station information, said history of mobile station information including a history of movement of said mobile station and received powers of perch channels from communication apparatuses surrounding said communication apparatus of said communication partner for past successful handover; and

said communication control apparatus selecting said at least a handover destination candidate communication apparatus according to said mobile station information sent from said mobile station and said history of mobile station information for past successful handover.

6. The handover control method as claimed in claim 5, comprising the steps of:

when said communication control apparatus selects a plurality of handover destination candidate communication apparatuses, said communication control apparatus determining priorities of said plurality of handover destination candidate communication apparatuses according to said mobile station information sent from said mobile station and said history of mobile station information for past successful handover.

7. The handover control method as claimed in claim 5, comprising the steps of:

said communication control apparatus holding said history of mobile station information for all communication apparatuses controlled by said communication control apparatus.

8. The handover control method as claimed in claim 5, comprising the steps of:

said communication control apparatus holding said history of mobile station information by each combination of a communication apparatus of handover origination and a communication apparatus of handover destination.

9. The handover control method as claimed in claim 8, comprising the steps of:

said communication control apparatus selecting a communication apparatus of handover destination corresponding to history data in said history of mobile station information in which a correlation value between said history data and said mobile station information sent from said mobile station is equal to or larger than a predetermined value.

10. The handover control method as claimed in claim 9, comprising the steps of:

when said communication control apparatus selects a plurality of handover destination candidate communication apparatuses, said communication control apparatus determining priorities of said plurality of handover destination candidate communication apparatuses according to said correlation value.

11. A mobile station in a mobile communication system which includes communication apparatuses having functions of base stations, said mobile station communicating with a communication apparatus of a communication partner, said mobile station comprising:

a handover control part for switching said communication apparatus of said communication partner to another communication apparatus when a communication quality value between said communication apparatus of said communication partner and said mobile station falls below a first threshold which is better than a limitation value by which communication is available.

13. The communication control apparatus as claimed in claim 12, said communication control apparatus comprising:

a part for selecting at least a handover destination candidate communication apparatus from among communication apparatuses surrounding said communication apparatus of said communication partner when said communication quality value falls below a second threshold which is better than said first threshold;

a part for keeping wireless resources of said at least a handover destination candidate communication apparatus which is selected; and

a part for notifying said mobile station of a handover destination candidate communication apparatus for which wireless resources are kept in said at least a handover destination candidate communication apparatus.

12. A communication control apparatus in a mobile communication system which includes communication apparatuses having functions of base stations, a mobile station and said communication control apparatus which controls connections between said communication apparatuses and said mobile station, said communication control apparatus comprising:

a part for allowing said mobile station to switch a communication apparatus of a communication partner to another communication apparatus when a communication quality value between said communication apparatus of said communication partner and said mobile station falls below a first threshold which is better than a limitation value by which communication is available.