Telecommunications – Radiotelephone system – Zoned or cellular telephone system
Reexamination Certificate
1999-06-28
2003-07-22
Trost, William (Department: 2683)
Telecommunications
Radiotelephone system
Zoned or cellular telephone system
C455S412100, C455S435100
Reexamination Certificate
active
06597909
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to call controlling in a mobile communication system, particularly to an apparatus and a method for performing a call control in a mobile communication system, which can offer an optimum service economically and efficiently.
In a mobile communication system, a visitor location register is used to store subscriber data required for offering various services, including information on a location of a base station (or mobile switching center) in the coverage area of which a mobile station resides (hereinafter simply called mobile station location) and information for identifying the subscriber.
Accordingly, even when the storage capacity of the visitor location register is not sufficient enough, call controlling apparatus and method which can process various requests for services (e.g., location registration, call originating, call incoming) to/from a portable telephone are in great demand.
2. Description of the Related Art
FIG. 1
is a block diagram showing principal devices of a conventional mobile communication system, in which an exchange is connected to a mobile station (abbreviated to MS) via a base station (not shown). The mobile station is a telephone which changes from location to location, such as a car telephone and a portable telephone.
exchange, which is comprised of a mobile switching center (abbreviated to MSC)
1
A and a visitor location register (abbreviated to VLR)
2
A, conducts a location registration for the mobile station on receiving a location registration request signal therefrom. It also establishes a connection between mobile stations by sending a call incoming request signal to a called mobile station on receiving a call originating request signal from a calling mobile station.
The MSC
1
A is comprised of a call controller (abbreviated to Call Cont in the figure)
11
a
and an MISC memory
12
a
. The MSC memory
12
a
has areas called call connection information areas (abbreviated to CIA in the figure) for a predetermined number of subscribers. The area stores therein call connection information required to connect a call, including the information on a base station, connection path, billing and routing. The call controller
11
a
controls so as to connect the call based on the information stored in the MSC memory
12
a.
The VLR
2
A is comprised of a call controller (abbreviated to Call Cont in the figure)
21
a
and a VLR memory
22
a
. The VLR memory
22
a
has a subscriber data area for.storing roaming subscriber's information, including the mobile station location, subscriber identifier (e.g., telephone number, telephone set number), authentication, restriction indicator, supplementary service and network identity, for a predetermined number of subscribers. The call controller
21
a
manages the subscriber data of a roaming subscriber in the VLR memory
22
a.
A home location register (hereinafter called HLR)
3
A is composed of a call controller
31
a
and an HLR memory
32
a
. The HLR memory
32
a
stores therein subscriber data for home subscribers, including the mobile station location, subscriber identifier (e.g., telephone number, telephone set number), authentication, restriction indicator, supplementary service. A call controller
31
a
manages subscriber data of the home subscribers in the HLR memory
32
a.
When the location registration request signal for a mobile station is received from the MSC
1
A, the VLR
2
A obtains a subscriber data area (abbreviated to SDA in the figure) for storing the subscriber data in the VLR memory
22
a
. Then, it retrieves the subscriber data from the HLR
3
A and stores and holds the retrieved subscriber data in the area while the mobile station resides in the network concerned. When receiving a call originating request signal from a mobile station or when sending a call incoming request signal to a mobile station, the VLR
2
A reads the subscriber data from the area to perform a call connection.
FIG. 2
is a flowchart illustrating a conventional location registration, which is performed by the VLR
2
A.
(1) When receiving from a mobile station (MS) a location registration request signal including the mobile station location information, the MSC
1
A requests the VLR
2
A to register the location.
(2) The VLR
2
A attempts to obtain the subscriber data area in the VLR memory
22
a.
(3) When the attempt is successful, the VLR
2
A requests the HLR
3
A to reply with the subscriber data of the mobile station.
(4) The VLR
2
A stores the replied subscriber data in the obtained subscriber data area and thereafter, informs the MSC
1
A of completion of the location registration (hereinafter, the operation of steps (3) and (4) is called normal processing of the location registration).
(5) If the attempt in step (2) is unsuccessful, the VLR
2
A indicates the MSC
1
A to disconnect the call.
According to the conventional method as described above, it was a problem that when there was no subscriber data area left in the VLR memory
22
a
, the VLR
2
A had to reject all the service requests for location registration, call originating, call incoming, etc., from/to a roaming subscriber.
It was another problem that increasing the storage capacity of the VLR memory
22
a
to overcome the above problem increases the cost of the VLR
2
A and therefore the cost of the system.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an apparatus and a method for performing a call control in a mobile communication system, which can offer an optimum service to the mobile station efficiently without rejecting the service requests from/to a roaming subscriber.
It is another object of the present invention to provide an apparatus and a method for performing a call control in a mobile communication system, which can offer an optimum service economically with a small amount of storage capacity of the visitor location register memory.
To achieve the above and other objects, the present invention provides determination means and storing means. In an apparatus for performing a call control in a mobile communication system including a first storage storing subscriber data for a home subscriber, a second storage storing call connection information and a third storage for storing subscriber data for a roaming subscriber, the determination means determines in response to a service request signal, that subscriber data is to be stored in the third storage and that there is no area therein for storing the subscriber data. Based on the determining by the determination means, the storing means retrieves the subscriber data from the first storage and stores the retrieved data in a second storage area. Also, the present invention provides the aforesaid determination means and overwrite means. Based on the determining by the determination means, the overwrite means retrieves the subscriber data from the first storage and overwrites the retrieved data in a third storage area.
REFERENCES:
patent: 5594942 (1997-01-01), Antic et al.
patent: 5903627 (1999-05-01), Shaffer et al.
patent: 6021327 (2000-02-01), Nguyen et al.
patent: 6078811 (2000-06-01), Lin et al.
Sakai Kenichiro
Takubo Hiroshi
Fijitsu Limited
Katten Muchin Zavis & Rosenman
Nguyen Simon
Trost William
LandOfFree
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