Telecommunications – Radiotelephone system – Zoned or cellular telephone system
Reexamination Certificate
2000-02-17
2003-07-15
Trost, William (Department: 2683)
Telecommunications
Radiotelephone system
Zoned or cellular telephone system
C455S432300, C455S560000, C455S422100, C455S445000
Reexamination Certificate
active
06594490
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to a mobile communication system and, more particularly, to a mobile communication system that has an active home location register (HLR) and a standby home location register which includes a database having the same contents as those of a database of the active home location register, and that has the functions of autonomously recovering from a mobile-station-location-information loss phenomenon which may be caused when the system performs switching between the active and standby home location registers in response to an occurrence of a fault.
2. Description of the Related Art
A conventional mobile communication system comprises an active home location register, a standby home location register which includes a database having the same contents as those of the active home location register, visitor location registers (VLR), mobile switching centers (MSCs), and mobile stations (MSs). When a fault occurs in the active home location register of this system, the active home location register is switched to the standby home location register which now serves as a new active home location register. Thus, the system continues operation.
The contents of the database of the standby home location register are periodically updated in such a manner as to match the contents of the database of the active home location register. Therefore, generally, even after the active home location register is switched to the standby home location register as described above, the contents of the database of the new active home location register match those of the database of an old active home location register. Consequently, it is expected that the system will continue normal operation.
As described above, the conventional system periodically updates the contents of the database of the standby home location register. However, when a fault occurs in the active home location register, the active home location register is immediately switched to the standby home location register. This results in a difference in contents between the database of the old active home location register used before an occurrence of a fault and that of the new active home location register (namely, the old standby home location register) used after the occurrence of the fault.
FIGS. 1
to
3
illustrate an example of such a conventional system.
FIG. 1
shows the constitution of an example of an ordinary mobile communication network.
As shown in this figure, an active home location register (ACT-HLR)
1
and a standby home location register (STABY-HLR)
2
are connected to a network
3
including a portable telephone network and an automobile telephone network. Further, each of areas (AREAa and AREAb)
4
and
5
under the control of the network
3
is provided with a corresponding one of visitor location registers (VLRs)
7
and
9
for registering station location information on the location of a mobile station therein and a corresponding one of mobile switching centers (MSC)
6
and
8
for performing switching between the mobile stations.
In the case of this example, a mobile station (MS-X)
10
, such as a portable telephone or an automobile telephone, is present in the area
4
. The location of this mobile station is registered. Therefore, the mobile switching center
6
and the visitor location register
7
provided in the area
4
hold the profile (indicated as MS-X) of the mobile station
10
. Further, the mobile station and the station location information thereof are respectively registered (as indicated by the expression “MS-X: AREAa”) in the active home location register
1
and the standby home location register
2
through the network
3
.
FIG. 2
illustrates an example of the case that a fault occurs in the active home location register of FIG.
1
.
That is, this figure illustrates the case in which the mobile station
10
moves from the area
4
to the area
5
and then makes a request for registration of the location thereof in the area
5
, and in which the registration of the location thereof is subsequently completed. Thus, the profile of the mobile station
10
is deleted from the mobile switching center
6
and the visitor location register
7
in the area
4
. Moreover, the profile of the mobile station
10
is copied from the active home location register
1
to the mobile switching center
8
and the visitor location register
9
in the area
5
.
Although the latest registered location information (AREAb) of the mobile station
10
is registered in the active home location register
1
, the database of the standby home location register
2
of this example is not updated yet. Therefore, the registered location information (hereunder sometimes referred to as location registration information) of the mobile station
10
is still registered in the old registration area (AREAa).
FIG. 3
illustrates an example of the aforementioned conventional location registration sequence.
Incidentally, it is supposed herein (and in the following descriptions of examples) that IS-41-C (Interim Standard
41
Revision C) standardized in north America is employed as a signal protocol for a mobile communication system, in which signals are transferred through a signal network. The aforementioned protocol is generically called MAP (Mobile Application Protocol/Part).
As shown in
FIG. 3
, the mobile station
10
moves from the area
4
to the area
5
and then transmits a location registration request message to the mobile switching center
8
in the area
5
in which the station
10
is present (step S
101
). Subsequently, the mobile switching center
8
transmits a location registration request message (REGNOT) concerning the mobile station
10
to the visitor location register
9
(step S
102
), which then transmits the location registration request message to the active home location register
1
(step S
103
).
After receiving this message, the active home location register
1
transmits a location registration canceling message (REGCANC)to the visitor location register
7
(step S
104
) in a current registration area (AREAa). Then, the visitor location register
7
transmits a location registration canceling request message to the mobile switching center
6
(step S
105
). If the mobile switching center
6
has the profile of the mobile station
10
, the center
6
deletes this profile and returns a location-registration-canceling-request response message (regcanc) to the visitor location register
7
(step S
106
).
When the active home location register
1
receives the location-registration-canceling-request response message from the visitor location register
7
, the register
1
updates the registration area (AREAa), in which the profile of the registered mobile station
10
is registered, to the latest registration area (AREAb) and then transmits a location-registration-request response message (regnot) to the visitor location register
9
provided in the area
5
(steps S
108
to S
110
). Subsequently, the visitor location register
9
provided in the area
5
registers the profile of the mobile station
10
, which is contained in the location-registration-request response message, therein and transmits a location-registration-request response message to the mobile switching center
8
(steps S
110
to S
112
). Similarly, the mobile switching center
8
registers the profile of the mobile station
10
therein.
Incidentally, there are the following two manners of transmission of the profile from the home location register to the visitor location register and the mobile switching center: a) transmission of the profile as a parameter of a profile transferring message; and b) transmission of the profile as a parameter of a location-registration-request response message. Although only the manner b) has been described in the foregoing description of the aforementioned example, the manner a) may be employed instead of the manner b).
Meanwhile,
FIG. 2
illustrates the case that a fault occurs in the active home location register
Fukazawa Mitsunori
Toyoda Takamitsu
Ushiki Kazumasa
Ferguson Keith
Fujitsu Limited
Katten Muchin Zavis & Rosenman
Trost William
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