Mobile radio communication system, mobile station, and method for controlling diversity hand-over branch

• US 6,728,227 B1
• Filed: 02/04/1999
• Issued: 04/27/2004
• Est. Priority Date: 06/04/1997
• Status: Expired due to Term

• Current Assignee: NTT Docomo Incorporated (Nippon Telegraph and Telephone Corporation)
• Original Assignee: NTT Docomo Incorporated (Nippon Telegraph and Telephone Corporation)
• Inventors: Sato, Takaaki, Tamura, Motoshi, Ohtani, Tomoyuki
• Primary Examiner(s): CUMMING, WILLIAM D
• Application Number:
  US09/230,956
• Time in Patent Office: 1,909 Days
• Field of Search: 455/436, 455/438, 455/439, 455/442, 455/443, 455/133, 455/135, 455/522, 455/450, 370/321, 370/322, 370/323, 370/335, 370/331, 370/334, 370/252, 370/394, 370/342, 375/138, 342/457, 342/450
• US Class Current: 370/331
• CPC Class Codes: H04B 7/022 Site diversity; Macro-diversity using two or more spaced independent antennas H04B7/04
• CPC Class Codes: H04B 7/0491 using two or more sectors, i.e. sector diversity
• CPC Class Codes: H04W 36/08 Reselecting an access point
• CPC Class Codes: H04W 36/18 for allowing seamless reselection, e.g. soft reselection
• CPC Class Codes: H04W 36/28 involving a plurality of connections, e.g. multi-call or multi-bearer connections
• CPC Class Codes: H04W 36/30 by measured or perceived connection quality data
• CPC Class Codes: H04W 92/04 Interfaces between hierarchically different network devices
• CPC Class Codes: H04W 92/20 between access points
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

A branch candidate selecting method by a mobile station and a diversity handover control method on a network side in DHO performance are provided which consider a maximum cable branch number and a maximum radio branch number of the mobile station, when the mobile station detects a plurality of addition branch candidates and deletion branch candidates. The mobile station inserts a plurality of addition branch candidates and deletion branch candidates, that is, all the DHO candidates into one handover trigger signal, and notifies the network. The addition branch candidates are put into addition information parameters in the handover trigger signal, and the deletion branch candidates are put into deletion information parameters. To simplify processing on the network side, the network side separates the addition branch candidates from the deletion branch candidates, and carries out sequential processing of them independently.

Claims

1. A mobile communication system including a mobile station, a plurality of base stations and a switching center connected to said plurality of base stations, said mobile communication system carries out diversity handover in which said mobile station communicates with said plurality of base stations simultaneously, wherein:

said mobile station comprises means for notifying said switching center of information on a plurality of branches including addition branch candidates and communicating branches, and information indicative of precedence of said plurality of branches to be used in the diversity handover, and

said switching center comprises means for receiving the information on said plurality of branches and information indicative thereof and establishing a communication branches in order of the precedence up to a maximum cable branch number that can be processed simultaneously by said switching center when a sum total of the number of the communicating branches and the number of the addition branch candidates exceeds a maximum radio branch number simultaneously establishable in communications between said mobile station and said base stations.

2. A diversity handover control method in a mobile communication system including a mobile station, a plurality of base stations, and a switching center connected to said plurality of base stations, said mobile communication system carries out diversity handover in which said mobile station communicates with said plurality of base stations simultaneously, comprising the steps of:

said mobile station notifying said switching center of information on a plurality of branches including one or more of addition branch candidates and information indicative of precedence of said plurality of branches to be used in the diversity handover;

said switching center receiving the information on said plurality of branches and information indicative thereof; and

establishing communication branches for the diversity handover using said addition branch candidates in order of the precedence, wherein radio branches are set after setting of cable branches.

3. A diversity handover control method as claimed in claim 2, further comprising the steps of:

said mobile station notifying said switching center of information on a plurality of branches including one or more of deletion branches, and

said switching center deleting said deletion branches from communication branches for the diversity handover based on the information on one or more of said deletion branches, wherein said cable branches are deleted after deletion of said radio branches.

4. A diversity handover control method as claimed in claim 2, wherein the information on said plurality of branches includes information on one or more of deletion branches, and further comprising the step of:

said switching center deleting communicating branches corresponding to said deletion branches, wherein said establishing step is performed after said deleting step.

5. A diversity handover control method as claimed in claim 2, wherein the information on said plurality of branches includes information on communicating branches, and said establishing step includes the step of:

said switching center establishing a communication branches in order of the precedence up to a maximum cable branch number that can be processed simultaneously by said switching center when a sum total of the number of communicating branches and the number of the addition branch candidates exceeds a maximum radio branch number simultaneously establishable in communications between said mobile station and said base stations.

6. A diversity handover control method as claimed in claim 2, wherein the information on said plurality of branches includes information on one or more of deletion branches and communicating branches, and further comprising the steps of:

said switching center receiving said information on said plurality of branches;

deleting branches corresponding to said deletion branches from communicating branches for the diversity handover;

establishing a communication branches in order of the precedence up to a maximum cable branch number that can be processed simultaneously by said switching center when a sum total of the number of said communicating branches and the number of said addition branch candidates exceeds a maximum radio branch number simultaneously establishable in communications between said mobile station and said base stations; and

establishing communication branches using all of said addition branch candidates when the sum total of the number of communicating branches and the number of the addition branch candidates does not exceed the maximum radio branch number simultaneously establishable in communications between said mobile station and said base stations.