Maintaining a group call in a mobile communications system

• US 6,292,670 B1
• Filed: 06/30/1997
• Issued: 09/18/2001
• Est. Priority Date: 12/28/1994
• Status: Expired due to Fees

• Current Assignee: Cassidian Finland OY
• Original Assignee: Nokia Telecommunications Oy (Nokia Corporation)
• Inventors: Kauria, Sirpa, Lassfolk, Christina
• Primary Examiner(s): Vo, Nguyen
• Assistant Examiner(s): Bhattacharya, Sam
• Application Number:
  US08/860,561
• Time in Patent Office: 1,541 Days
• Field of Search: 455/422, 455/426, 455/432, 455/435, 455/436, 455/438, 455/439, 455/450, 455/455, 455/458, 455/459, 455/516, 455/517, 455/518, 455/519, 455/520, 455/524, 455/525, 455/509
• US Class Current: 455/518
• CPC Class Codes: H04W 28/26 Resource reservation
• CPC Class Codes: H04W 36/0009 for a plurality of users or terminals, e.g. group communication or moving wireless networks user group management H04W4/08; processing of subscriber group data H04W8/186
• CPC Class Codes: H04W 36/08 Reselecting an access point
• CPC Class Codes: H04W 72/30 Resource management for broadcast services
• CPC Class Codes: H04W 84/08 Trunked mobile radio systems

Abstract

In a method for maintaining a group call in a mobile communication system, a mobile station is registered to a first base station and starts a group call. A traffic channel is reserved by the first base station for the group call, and the mobile station changes over to communicating on the traffic channel reserved from the first base station. To ensure an uninterrupted group call, a ‘follow me’ function is activated for the group call. In response to activating the ‘follow me’ function for the group call and reservation of a traffic channel by the first base station for the group call, a traffic channel is reserved from each of the desired second base station adjacent to the first base station for the group call. When some of the mobile stations participating in the group call change over to using a second base station adjacent to the first base station, the mobile station changes over to communicating on the traffic channel reserved from the base station for the group call.

Claims

1. A method for maintaining a group call in a mobile communications system in which in said group call a plurality of mobile stations communicate with each other, said mobile communications system including one or more first base stations and second base stations located around the first base stations, and one or more mobile stations that are able to communicate with said base stations in said group call and a database, said method comprising:

a) registering said one or more mobile stations in said mobile communications system;

b) activating into said database of said mobile communications system a follow me function for said group call in order for said group call to follow uninterruptedly said mobile station participating in said group call from a first base station to said second base station;

c) reserving a traffic channel for said group call from said first base station;

d) said mobile station changing over to communicating on said traffic channel reserved from said first base station;

e) in response to reserving said traffic channel from said first base station for said group call and in response to said activation of said follow me function, reserving a traffic channel simultaneously from a plurality of desired second base stations adjacent to said first base station for said group call;

f) upon changing over to using a second base station adjacent to said first base station, the mobile station participating in said group call changing over to communicating on the traffic channel reserved for said call from said second base station;

g) checking, in response to activating said follow me function for said group call, and registering of said mobile station to said second base station, whether a traffic channel has been reserved previously for said group call from all of said desired third base stations adjacent to said second base station;

h) reserving a traffic channel for said group call from said desired third base stations adjacent to said second base station from which no traffic channel has been reserved previously for said group call;

i) checking among all said desired second base stations which base stations are not included in said desired third base stations adjacent to said second base station whether a mobile station participating in said group call is registered to said base station, or such a base station to which said base station is a desired adjacent base station; and

j) canceling said reservation of a traffic channel for said group call regarding said desired second base stations which are not included in said desired third base stations adjacent to said second base station, and to which base stations or base station to which said base station is a desired adjacent base station, none of the mobile stations participating in said group call is registered.

2. The method as claimed in claim 1,

wherein said follow me function is activated so that a subscriber sends said mobile communication system a request to activate said follow me function for said group call.

3. The method as claimed in claim 1, wherein

activating said follow me function for said group call so that upon establishing said group call in response to a subscriber number of said group call to be maintained, said mobile communication system activates said follow me function.

4. The method as claimed in claim 3,

wherein said mobile communication system activating said follow me function for said group call after detecting from said database that said follow me function has been defined for said subscriber number.

5. The method as claimed in claim 1,

wherein said mobile communication system communicating to the mobile station within an area of said first base station, said traffic channels that are reserved for said group call in the desired second base stations adjacent to said first base station, and

wherein the mobile station changing over to communicating on some of said traffic channels of said adjacent second base stations.

6. The method as claimed in claim 5,

wherein said changeover of the mobile station to communicating on said traffic channel of said second base station being performed so that the mobile station is registered to said second base station on said traffic channel of said second base station.

7. The method as claimed in claim 1, wherein said desired second base stations and said desired third base stations are defined in said database of said mobile communication system so that regarding each base station, the desired base stations adjacent to the base station in question are shown to relate to that base station.

8. The method as claimed in 1, further comprising:

sending said mobile communication system a request to deactivate said group call as far as the mobile station is concerned; and

in response to said request, canceling said reservation of said traffic channels reserved for said group call at the base station adjacent to said base station to which said mobile station is registered, provided that none of the mobile stations participating in said group call is registered to said base station, or to a base station to which said base station is a desired adjacent base station.

9. The method as claimed in 1, further comprising:

sending said mobile communication system a request to terminate said group call regarding the mobile station; and

in response to said request, canceling said reservation of said traffic channels reserved for said group call at the base station to which said mobile station is registered, as well as at the base stations adjacent to said base station, provided that none of the mobile stations participating in said group call is registered to said base station, or to a base station to which said base station is a desired adjacent base station.

10. The method as claimed in 1 wherein

in case of a mobile station other than one participating in said group call communicating on said traffic channel reserved for said group call of said second base station when a mobile station participating in said group call needs said channel for operation, said mobile communication system commanding the other mobile station participating in another call to leave said traffic channel.

11. A mobile communication system including one or more first base stations and second base stations located around the first base station, and one or more mobile stations able to communicate with said base stations, comprising:

a database arranged to maintain information on whether a follow me function has been activated for a group call to be maintained, wherein in said group call, a plurality of mobile stations communicate with each other, in order for said group call to follow uninterrupted, said mobile station participating in said group call from one said first base station to said second base stations; and

a reservation means, responsive to activating said follow me function for said group call and to reserving a traffic channel from the first base station for said group call, which reserves a traffic channel simultaneously from a plurality of desired second base stations adjacent to the first base station for said group call,

wherein said reservation means being arranged, in response to activating said follow me function for said group call and to registering of said mobile station to said second base station, to reserve a traffic channel from each desired third base stations adjacent to said second base station for said group call provided that no traffic channel has previously been reserved for said group call from said third base station, and

wherein said reservations means being further arranged to cancel reservation of said traffic channels reserved in said desired second base stations for said group call, which base stations are not included in the desired third base stations adjacent to said second base station, provided that none of the mobile stations participating in said group call is registered to said base station, or to a base station to which said base station is a desired adjacent base station.