Cell selection system, cell selection method, and mobile terminal

• US 8,374,152 B2
• Filed: 08/22/2008
• Issued: 02/12/2013
• Est. Priority Date: 10/26/2007
• Status: Active Grant

• Current Assignee: Sovereign Peak Ventures, LLC (Dominion Harbor Enterprises, LLC)
• Original Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Inventors: Aoyama, Takahisa, Hirano, Jun, Aramaki, Takashi, Fukui, Akito
• Primary Examiner(s): SCHEIBEL, ROBERT C
• Application Number:
  US12/739,883
• Publication Number:
  US 20100278146A1
• Time in Patent Office: 1,635 Days
• Field of Search: None
• US Class Current: 370/331
• CPC Class Codes: H04W 48/20 Selecting an access point

Abstract

A cell selection system selects a cell to be used for communications by a mobile terminal in a network having a cell of a mobile phone network and WLAN cells included in the cell. Broadcast information including cell selection information is transmitted in the cell of the mobile phone network. This cell selection information has cell change judgment parameters whose patterns are less than the WLAN cells. The mobile terminal reads the cell selection information from the broadcast information of the mobile phone network, determines a parameter to be used for the judgment on cell selection of a WLAN cell, and judges whether the cell can be changed or not. The cell reselection system restricts the amount of data in the broadcast information even with an increase in the number of WLAN cells included in the cell of the mobile phone network.

Claims

1. A cell selection system for selecting a cell to be used for communications by a mobile terminal in a network, the cell selection system comprising:

a first cell using a first communication protocol;

a plurality of second cells, the plurality of second cells'"'"' coverage is under the first cell'"'"'s coverage and uses a second communication protocol that is different for the first communication protocol; and

a mobile terminal supporting communications using the first and second communication protocols in the first and second cells in the network,

wherein broadcast information having cell selection information is transmitted in the first cell, the cell selection information including cell change judgment parameters having a number of patterns that is less than a number of the second cells, and

the mobile terminal receives the broadcast information of the first cell and broadcast information of one of the second cells;

reads the cell selection information from the broadcast information of the first cell;

determines, from the number of patterns of parameters included in the read cell selection information, a parameter to be used for making a judgment on cell selection of a second cell based on the broadcast information of the second cell; and

judges based on the determined parameter whether to change a communication connection of the mobile terminal from the first cell to the second cell.

2. The cell selection system according to claim 1,

wherein the cell selection information includes a common parameter that is commonly used for judgment on the cell selection to all the second cells, and

the mobile terminal judges whether the first cell is changeable to the second cell based on the common parameter and the parameter determined based on the broadcast information of the second cell.

3. The cell selection system according to claim 1, wherein the mobile terminal determines the parameter by information on whether a paging area registration is made with the second cell when in an idle mode, and determines the parameter regardless of the presence of a paging area registration with the second cell when establishing the communication connection.

5. The cell selection system according to claim 1, wherein the mobile terminal selects a cell using the cell selection information obtained from the broadcast information of the first cell if the reception quality of the broadcast information of the first cell is a predetermined threshold or higher, even after the mobile terminal selects the second cell.

10. The cell selection system according to claim 2, wherein the mobile terminal determines the parameter by information on whether a paging area registration is made with the second cell when in an idle mode, and determines the parameter regardless of the presence of a paging area registration with the second cell when establishing the communication connection.

11. The cell selection system according to claim 2, wherein the mobile terminal selects a cell using the cell selection information obtained from the broadcast information of the first cell if the reception quality of the broadcast information of the first cell is a predetermined threshold or higher, even after the mobile terminal selects the second cell.

12. The cell selection system according to claim 3, wherein the mobile terminal selects a cell using the cell selection information obtained from the broadcast information of the first cell if the reception quality of the broadcast information of the first cell is a predetermined threshold or higher, even after the mobile terminal selects the second cell.

14. The cell selection system according to claim 1, wherein the mobile terminal determines the parameter by information on whether a paging area registration is made with the second cell or not.

15. The cell selection system according to claim 2, wherein the mobile terminal determines the parameter by information on whether a paging area registration is made with the second cell or not.

4. A cell selection system for selecting a cell to be used for communications by a mobile terminal in a network, the cell selection system comprising:

a first cell using a first communication protocol;

a plurality of second cells, the plurality of second cells'"'"' coverage is under the first cell'"'"'s coverage and uses a second communication protocol that is different for the first communication protocol; and

a mobile terminal supporting communications using the first and second communication protocols in the first and second cells in the network,

wherein broadcast information having cell selection information is transmitted in the first cell, the cell selection information including a common parameter that is commonly used for a judgment on cell selection of all the second cells,

in each of the second cells, broadcast information is transmitted including an individual parameter that is individually used for a judgment on cell selection of a second cell, and

the mobile terminal receives the broadcast information of the first cell and the broadcast information of one of the second cells;

reads the common parameter from the broadcast information of the first cell;

reads the individual parameter from the broadcast information of the second cell; and

judges based on the common and individual parameters whether to change a communication connection of the mobile terminal from the first cell to the second cell.

13. The cell selection system according to claim 4, wherein the mobile terminal selects a cell using the cell selection information obtained from the broadcast information of the first cell if the reception quality of the broadcast information of the first cell is a predetermined threshold or higher, even after the mobile terminal selects the second cell.

6. A cell selection method for selecting a cell to be used for communications by a mobile terminal in a network having a first cell using a first communication protocol and a plurality of second cells which are included in the first cell and uses a second communication protocol which is different from that for the first cell, the mobile terminal supporting communications using the first and second communication protocols in both the first and second cells, the cell selection method comprising:

transmitting, in the first cell, broadcast information including cell selection information having cell change judgment parameters with a number of patterns that are less than a number of the second cells;

transmitting broadcast information in the second cells;

receiving in the mobile terminal the broadcast information of the first cell and the broadcast information of one of the second cells;

reading the cell selection information from the broadcast information of the first cell;

determining, from the number of patterns of parameters included in the cell selection information, a parameter to be used for a judgment on cell selection of a second cell based on the broadcast information of the second cell;

judging by the determined parameter whether to change a communication connection of the mobile terminal from the first cell to the second; and

selecting the first cell as the cell to be used for communications by the mobile terminal if the change is judged to be impossible, and selecting the second cell as the cell to be used for communications by the mobile terminal if the change is judged to be possible.

7. A cell selection method for selecting a cell to be used for communications by a mobile terminal in a network having a first cell using a first communication protocol and a plurality of second cells which are included in the first cell and uses a second protocol which is different from that for the first cell, the mobile terminal supporting communications using the first and second communication protocols in both the first and second cells, the cell selection method comprising:

transmitting, in the first cell, broadcast information including cell selection information comprising a common parameter that is commonly used for a judgment on cell selection of all the second cells;

transmitting, in each of the second cells, broadcast information including an individual parameter that is individually used for a judgment on cell selection of a second cell;

receiving in the mobile terminal broadcast information of the first cell and the broadcast information of one of the second cells;

reading the common parameter from the broadcast information of the first cell;

reading the individual parameter from the broadcast information of the second cell;

judging by the common and individual parameters whether to change a communication connection from the first cell to the second cell; and

selecting the first cell as the cell to be used for communications by the mobile terminal if the change is judged to be impossible, and selecting the second cell as the cell to be used for communications by the mobile terminal if the change is judged to be possible.

8. A mobile terminal used in a network having a first cell using a first communication protocol and a plurality of second cells which are included in the first cell and uses a second protocol which is different from that for the first cell, the mobile terminal supporting communications using the first and second communications protocols in both the first and second cells, the mobile terminal comprising:

a first broadcast information receiver for receiving broadcast information of the first cell including cell selection information having cell change judgment parameters with a number of patterns that are less than a number of the second cells;

a second broadcast information receiver for receiving broadcast information of one of the second cells;

a broadcast information processor for reading the cell selection information from the broadcast information of the first cell and determining, from the number of patterns of parameters included in the read cell selection information, a parameter to be used for a judgment on cell selection of a second cell based on the broadcast information of the second cell; and

a cell change controller for judging by the determined parameter whether to change a communication connection of the mobile terminal from the first cell to the second cell.

9. A mobile terminal used in a network having a first cell using a first communication protocol and a plurality of second cells which are included in the first cell and use a second communication protocol which is different from that for the first cell, the mobile terminal supporting communications using the first and second communication protocols in both the first and second cells, the mobile terminal comprising:

a first broadcast information receiver for receiving broadcast information of the first cell including cell selection information comprising a common parameter that is commonly used for a judgment on cell selection of all the second cells;

a second broadcast information receiver for receiving broadcast information of one of the second cells including an individual parameter that is individually used for a judgment on cell selection of a second cell;

a first broadcast information processor for reading the common parameter from the broadcast information of the first cell;

a second broadcast information processor for reading the individual parameter from the broadcast information of the second cell; and

a cell change controller for judging by the common and individual parameters whether to change a communication connection of the mobile terminal from the first cell to the second cell.