Telecommunications – Radiotelephone system – Zoned or cellular telephone system
Reexamination Certificate
1998-12-31
2002-04-30
Bost, Dwayne (Department: 2681)
Telecommunications
Radiotelephone system
Zoned or cellular telephone system
C455S456500, C455S433000, C455S411000
Reexamination Certificate
active
06381456
ABSTRACT:
TECHNICAL FIELD
The present invention relates to method for managing subscriber location information in a mobile communications system. When a mobile subscriber moves to another place, registration notification is carried out from a visitor location register(hereinafter, referring to VLR) to a home location register(HLR). In case that request for the registration notification and call processing procedure about the same subscriber is overlapped, the HLR protects multi-location registrations about the same subscriber until a previous registration notification is completed. Thereby, this invention relates to method for managing subscriber location information in a mobile communications system, for always maintaining a location information about a subscriber in a HLR and a VLR, correctly.
BACKGROUND
Generally, a digital mobile communications system using CDMA(Code Division Multiple Access) comprises a home location register(HLR) and a visitor location register(VLR). The HLR has a database for managing extra service information, location information, and etc., about mobile subscribers. The VLR is used by a mobile exchanges to search information which processes a call from/to subscriber visiting area. Accordingly, the HLR should maintain exact information about a plurality of subscribers. And also, the HLR should maintain temporary information in the single VLR only, in which the information is generated according as subscribers move.
However, there is no regulation about a concrete situation in a current mobile communications standard(IS-41-C). So, when other mobile network subscribers try to call, it is frequently disconnected because the HLR could not offer subscriber information, correctly.
FIG. 1
is a flow chart showing a registration notification(RN) procedure of a normal mobile subscriber. It tells a case that a mobile station(MS
1
) moves from a previous service system area(where a first visitor location register VLR
1
exists) to a new service system area(where a second visitor location register VLR
2
exists).
After the VLR
2
senses the MS
1
and sends a registration notification invoke(RNI) message of the MS
1
to the HLR according as the MS
1
moves(ST
1
), the HLR updates and saves a location of the MS
1
in database. Here, the VLR
1
has a subscriber record of the MS
1
. The HLR thus requests the VLR
1
to erase location information of the MS
1
(ST
2
). And then, VLR
1
erases the subscriber record of the MS
1
stored in the current database, and sends a registration cancellation return result(RCRR) message of MS
1
to the HLR(ST
3
). After receiving the message for erasing location, the HLR sends a registration notification return result(RNRR) message of the MS
1
to the VLR
2
(ST
4
). Accordingly, the VLR
2
may create a subscriber record of the MS
1
in the database.
FIG. 2
is a flow chart showing a call processing procedure of a mobile subscriber. In case that a calling party's MS requests the desired called party's mobile station(MS
2
) to call in which the MS
2
is in other service system area, the
FIG. 2
shows the procedure among a calling party's mobile switching center(MSC) and the HLR and a called party's mobile switching center(MSC
1
).
When the calling party's MS requests the MS
2
to call, the corresponding MSC of the calling party's MS sends a location request (LR) message of the MS
2
to the HLR(ST
11
). The HLR which received the LR message from the MSC, sends a routing request (RR) message of the MS
2
to a corresponding MSC
1
via VLR
1
of the MS
2
in order to know routing information of the MS
2
(ST
12
). The called party's MSC
1
receives the RR message and allocates routing information TLDN(temporary local directory number). At this time, the VLR
1
has a subscriber record of the MS
2
. In case of receiving the TLDN of the MS
2
, the MSC
1
sends a routing request return result(RRRR) message of the MS
2
to the HLR(ST
13
). The HLR which received the RRRR message sends a location request return result(LRRR) message of the MS
2
to the calling party's MSC(ST
14
).
Hereinafter, a call processing procedure of a mobile subscriber will be explained in case that the HLR has incorrect location information of the MS
2
with unrecognized reasons.
First, the calling party's MSC sends a location request invoke(LRI) message of the MS
2
to the HLR, showing in below of FIG.
2
(ST
21
). The HLR sends a routing request (RR) message to the VLR
1
of the MS
2
in order to know location information of the MS
2
(ST
22
). Here, the VLR
1
does not have the subscriber record of the MS
2
. Accordingly, the VLR
1
sends an error code as well as routing request(RR) error message of the MS
2
to the HLR, in which the error massage indicates that the subscriber can not be recognized(ST
23
).
Here, the HLR clears the subscriber location information stored in the HLR database(ST
24
). And then the HLR sends a location request return result(LRRR) message with an access denied reason parameter of the MS
2
to the calling party's MSC. As a result, the call is failed.
In case that a mobile station(MS
3
) moves to a new serving area, location information of the subscriber is registered on at least two VLRs, respectively. And it will be now explained in
FIG. 3
showing a registration notification(RN) flowchart of a mobile subscriber.
When a mobile station(MS
3
) moves to a new serving area, the VLR
2
in a new serving area senses the MS
3
and requests the HLR a first registration notification invoke(RNI) of the MS
3
(ST
1
). The HLR updates the location of the MS
3
and stores a previous location on database. Here, the VLR
1
still has the subscriber record of the MS
3
. Accordingly, the HLR requests the VLR
1
registration cancellation(RC)of the MS
3
(ST
2
).
But, in case that the VLR
2
requests the HLR a second RNI(ST
3
), the HLR answers about a registration notification request(RNR) without any registration cancellation(RC) procedure because it's from a current service system, again. Accordingly, the HLR sends a second registration notification return result(RNRR) message of the MS
3
to the VLR
2
(ST
4
). Consequently, a subscriber record of the MS
3
is created in the VLR
2
.
Besides, in case that a registration cancellation request(RCR) of the MS
3
requested by the HLR to the VLR
1
, is not carried out because the MS
3
is busy, and etc., the VLR
1
sends a registration cancellation return result(RCRR) message with a cancellation denied parameter to the HLR(ST
5
). Because the RCR of the MS
3
is denied, the HLR restores a location information of the database and sends a first RNRR message with an access denied reason parameter to the VLR
2
in order to re-register the location of the MS
3
in the VLR
1
where the previous service system is provided (ST
6
).
The HLR is operated in the same way when the answering information is lost in the step (ST
2
or ST
5
). Even though a first registration notification(RN) of the MS
3
failed, the database of the VLR
2
already has the subscriber record of the MS
3
by requesting the second RN(ST
3
) and also, the subscriber record which established in the database of the VLR
1
, was not canceled. Consequently, both visitor location registers VLR
1
, VLR
2
have a subscriber record of the MS
3
.
Like this way, when the other mobile subscriber tries to call, the HLR can not carry out a normal call processing because the HLR and VLR have incorrect information about a corresponding subscriber.
FIG. 4
shows a signal processing flowchart for explaining errors. The errors may be happened in case that a registration notification(RN) and call processing procedures about same mobile subscriber are overlapped showing in
FIG. 1
to
FIG. 2
, when a mobile station(MS
4
) moves to another serving area.
In case that the MS
4
moves to a new serving area, a VLR
2
senses the MS
4
and requests a registration notification invoke(RNI) to the HLR(ST
31
). The HLR updates the location of the MS
4
and stores the previous location in database. The VLR
1
has a subscriber record of the MS
Bost Dwayne
LG Information & Communications Ltd.
Long Aldridge & Norman LLP
Trinh Sonny
LandOfFree
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