U.S. patent number RE45,301 [Application Number 10/827,698] was granted by the patent office on 2014-12-23 for location management in a mobile telecommunication system.
This patent grant is currently assigned to Nokia Corporation. The grantee listed for this patent is Juha Back, Jari Hartikainen, Serge Haumont, Matti Keskinen, Heikki Lindholm, Juhapekka Niemi, Lauri Soderbacka. Invention is credited to Juha Back, Jari Hartikainen, Serge Haumont, Matti Keskinen, Heikki Lindholm, Juhapekka Niemi, Lauri Soderbacka.
United States Patent |
RE45,301 |
Haumont , et al. |
December 23, 2014 |
Location management in a mobile telecommunication system
Abstract
The basic idea of the invention is to separate the location area
used in the RAN and the reporting area used when reporting the
location of the mobile to the core network. The size of the
location area is selected preferably in the RAN based on the
services used by the subscriber to optimize the use of radio
resources. A reporting area comprises one or a plurality of
location areas. The size of a reporting area is selected based on
the accuracy of location information needed in the core network.
The RAN informs the core network when a subscriber moves out of his
current location area. The core network and the radio access
network negotiate the size of the reporting area prior to the
activation of the service. Additionally, the reporting areas can be
renegotiated when the service is in the active state.
Inventors: |
Haumont; Serge (Helsinki,
FI), Lindholm; Heikki (Helsinki, FI),
Soderbacka; Lauri (Fleet, GB), Back; Juha
(Helsinki, FI), Niemi; Juhapekka (Tampere,
FI), Keskinen; Matti (Jarvenpaa, FI),
Hartikainen; Jari (Salo, FI) |
Applicant: |
Name |
City |
State |
Country |
Type |
Haumont; Serge
Lindholm; Heikki
Soderbacka; Lauri
Back; Juha
Niemi; Juhapekka
Keskinen; Matti
Hartikainen; Jari |
Helsinki
Helsinki
Fleet
Helsinki
Tampere
Jarvenpaa
Salo |
N/A
N/A
N/A
N/A
N/A
N/A
N/A |
FI
FI
GB
FI
FI
FI
FI |
|
|
Assignee: |
Nokia Corporation (Espoo,
FI)
|
Family
ID: |
8550117 |
Appl.
No.: |
10/827,698 |
Filed: |
April 20, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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PCT/FI98/00971 |
Dec 11, 1998 |
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Reissue of: |
09591679 |
Jun 9, 2000 |
6584314 |
Jun 24, 2003 |
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Foreign Application Priority Data
Current U.S.
Class: |
455/435.1;
370/337; 455/456.2; 370/338; 455/433; 455/422.1; 455/456.1;
455/440 |
Current CPC
Class: |
H04W
60/00 (20130101); H04W 68/00 (20130101) |
Current International
Class: |
H04W
4/00 (20090101); H04W 36/00 (20090101); H04W
24/00 (20090101) |
Field of
Search: |
;455/433,440,456.2,432.1,435.1,436,437,442,443,445
;370/337,338,328,331 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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0 808 036 |
|
Nov 1997 |
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EP |
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9-51570 |
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Feb 1997 |
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JP |
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95/11577 |
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Apr 1995 |
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WO |
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95/28063 |
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Oct 1995 |
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WO |
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96/07277 |
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Mar 1996 |
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WO |
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96/39000 |
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Dec 1996 |
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WO |
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97/13387 |
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Apr 1997 |
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WO |
|
98/37721 |
|
Aug 1998 |
|
WO |
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98/37722 |
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Aug 1998 |
|
WO |
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Other References
Laatu (WO94/13114), "Location Updating in a Cellular Radio System",
Jun. 9, 1994, Fig.1 and pp. 1-12. cited by examiner .
Jun. 10, 1999 International Search Report for PCT/FI98/00971. cited
by applicant.
|
Primary Examiner: Kim; Wesley
Attorney, Agent or Firm: Squire Patton Boggs (US) LLP
Parent Case Text
This is a continuation of Application No. PCT/F198/00971 filed Dec.
11, 1998.
Claims
What is claimed is:
.[.1. A method of location management in a mobile telecommunication
system comprising mobile stations, at least one core network
providing telecommunication services, and a radio access network
providing connections between the mobile stations and the core
network, and in which system information concerning the location of
the mobile station is stored in the radio access network,
comprising tracking in the radio access network of the location of
the mobile station to the accuracy of a location area, determining
in the core network a reporting area comprising at least one
location area, informing the radio access network by the core
network of the reporting area determined, receiving at the radio
access network a location update from the mobile station,
determining by the radio access network based on the location
update whether or not the mobile station has moved out of the
reporting area, and sending by the radio access network to the core
network a report if the mobile station has moved out of the
reporting area..].
2. .[.The method according to claim 1,.]. .Iadd.A method of
location management in a mobile telecommunication system comprising
mobile stations, at least one core network providing
telecommunication services, and a radio access network providing
connections between the mobile stations and the core network, and
in which system information concerning the location of the mobile
station is stored in the radio access network, comprising tracking
in the radio access network of the location of the mobile station
to an accuracy of a location area, determining in the core network
a reporting area comprising at least one location area, informing
the radio access network by the core network of the reporting area
determined, receiving at the radio access network a location update
from the mobile station, determining by the radio access network
based on the location update whether or not the mobile station has
moved out of the reporting area, sending by the radio access
network to the core network a report if the mobile station has
moved out of the reporting area; and not sending the core network
said report if the mobile station has not moved out of the
reporting area,.Iaddend. wherein a plurality of location accuracy
levels is defined, each location accuracy level having location
areas of different sizes, and the radio access network selects one
of these accuracy levels to be used for tracking the mobile
station.
.[.3. The method according to claim 2, wherein the reporting area
is a location area of one location accuracy level..].
.[.4. The method according to claim 2, wherein the radio access
network selects the location accuracy level based on the services
currently used by a subscriber using the mobile station..].
.[.5. The method according to claim 2, wherein the radio access
network selects the location accuracy level based on service
parameters given by the core network..].
.[.6. The method according to claim 2, wherein the radio access
network selects the location accuracy level based on the past
behavior of a subscriber using the mobile station..].
.[.7. The method according to claim 6, wherein the behavior of the
subscriber is determined based on the number of pages that the
radio access network has performed to locate the mobile station and
the number of location updates that the mobile station has
performed..].
.[.8. The method according to claim 2, wherein the radio access
network informs the mobile station of the location accuracy level
to be used when tracking the mobile station..].
9. The method according to claim .[.1.]. .Iadd.2.Iaddend., wherein
the core network requests that a mobile station reauthenticates
itself when the mobile station moves to a new reporting area.
.[.10. The method according to claim 1, wherein the mobile station
is entitled to different services in different reporting
areas..].
11. The method according to claim .[.1.]. .Iadd.2.Iaddend., wherein
the mobile station is entitled to different qualities of service in
different reporting areas.
12. The method according to claim .[.1.]. .Iadd.2.Iaddend., wherein
the core network and the radio access network negotiate the size of
the reporting area to be used.
.[.13. The method according to claim 12, wherein the negotiation
takes place when the service is activated..].
.[.14. The method according to claim 12, wherein the negotiation
takes place when the service is in an activated state..].
15. The method according to claim .[.1.]. .Iadd.2.Iaddend., wherein
the service parameters for different service areas for the services
a subscriber using the mobile station has subscribed to are
specified and stored in the core network, the mobile station
initiates a location update process when entering into a new
reporting area, in response to having received the location update,
the radio access network forwards the new location information of
the mobile station to the core network, the core network receives
the new location information and defines a new service area for the
subscriber, checks the service parameters of services the
subscriber is entitled to in the new service area, and sends the
radio access network information about the new service parameters,
the radio access network receives the information about the new
service parameters and completes the location update process by
sending the mobile station a response.
.[.16. The method according to claim 1, wherein information about
reporting area configuration is stored in the mobile station, and
when entering a new service area, the mobile station initiates a
location update process, instructing the radio access network to
forward the new location information to the core network, and the
radio access network forwards the location information to the core
network..].
.[.17. The method according to claim 16, wherein the information
about the service area configuration is given as a list of
cells..].
.[.18. The method according to claim 16, wherein the information
about the reporting area configuration is given as coordinates of
the reporting area and the mobile station observes its coordinates
and initiates a location update when entering into a new reporting
area..].
.[.19. The radio access network for a mobile telecommunication
system comprising mobile stations, at least one core network
providing telecommunication services, and a radio access network,
providing connections between the mobile stations and the core
network, and in which system information concerning the location of
the mobile station is stored in the radio access network, the radio
access network adapted to use a location area configuration to
track the location of the mobile station on the accuracy of one
location area, receive information on a reporting area determined
by the core network, receive a location update from the mobile
station, determine, based on the location update, whether or not
the mobile station has moved out of the reporting area, and send
the core network a report if the mobile station has moved out of
the reporting area..].
.[.20. The network element for a radio access network of a mobile
telecommunication system comprising mobile stations, at least one
core network providing telecommunication services, and a radio
access network providing connections between the mobile stations
and the core network, and in which system information concerning
the location of the mobile station is stored in the radio access
network, the network element adapted to use a location area
configuration to track the location of the mobile station on the
accuracy of one location area, receive information on a reporting
area determined by the core network, receive a location update from
the mobile station, determine, based on the location update,
whether or not the mobile station has moved out of the reporting
area, and send the core network a report if the mobile station has
moved out of the reporting area..].
.[.21. The core network for a mobile telecommunication system
comprising mobile stations, at least one core network providing
connections between the mobile stations and the core network, and
in which system information concerning the location of the mobile
station is stored in a radio access network, and the radio access
network uses a location area configuration to track the location of
the mobile station on the accuracy of one location area, the core
network adapted to determine a service area comprising at least one
location area, inform the radio access network of the reporting
area determined, and to receive a report from the radio access
network when the mobile station has moved out of the reporting
area..].
.Iadd.22. A method, comprising: tracking a location of a mobile
station in a radio access network with an accuracy of a location
area, the radio access network providing connections between mobile
stations and a core network providing services to the mobile
stations; determining a reporting area comprising at least one
location area; determining a change in the location of the mobile
station when the mobile station moves from a first location area to
a second location area; reporting to the core network the change in
the location of the mobile station only when the mobile station
also moves from a first reporting area to a second reporting area;
and not reporting to the core network the change in the location of
the mobile station when the mobile station has not moved from the
first reporting area to the second reporting area, wherein the core
network requests that a mobile station authenticates itself when
the mobile station moves to a new reporting area..Iaddend.
.Iadd.23. The method according to claim 22, wherein the mobile
station is entitled to different qualities of service in different
reporting areas..Iaddend.
.Iadd.24. The method according to claim 22, wherein the core
network and the radio access network negotiate the size of the
reporting area to be used..Iaddend.
Description
FIELD OF THE INVENTION
This invention concerns location management in a mobile
telecommunication system.
BACKGROUND OF THE INVENTION
FIG. 1 shows a system in which one Radio Access Network RAN is
connected to a plurality of Core Networks CN. Such a RAN is planned
to be implemented in the Universal Mobile Telephony System UMTS
currently being standardized by ETSI (European Telecommunication
Standards Institute), for example. The RAN provides the radio
connection for the subscribers of a plurality of core networks and
is therefore also called Generic RAN, i.e. GRAN. The services are
provided by the core networks connected to the RAN using the
I.sub.u interface. In the figure, the GSM, UMTS, GPRS (General
Packet Radio Service), and ISDN (Integrated Services Digital
Network) core networks are shown. The Mobile Station MS can make
connections to the core networks using radio connections to the
RAN. The MS makes radio connections to the base stations of the
radio access network. The RAN routes the connections to the core
network whose service the subscriber is currently using.
Information concerning the location of the mobile station is needed
in the radio access network for routing incoming calls and other
services provided by the core networks. For location management,
the geographical area served by a radio access network is divided
into one or a plurality of Location Areas LA. The location of a
mobile station is tracked with an accuracy of one location area.
Within the location area, the mobile station can move without
informing the RAN about its movements. The location area consists
of one or a plurality of cells, a cell being the coverage area of a
base station. The base stations send information about themselves
continuously. This information comprises the identity and the
location area of the base station. Based on this information, the
mobile station knows the location area it is visiting at all times.
Additionally, the mobile knows the identity of the location area of
its latest location update, i.e. its currently specified location
area. When recognizing that the location area identification sent
by the base station having the best signal is different from the
location area of the mobile, the mobile initiates a location update
procedure. In the procedure, the mobile contacts the RAN to inform
it of the new location area.
The size of the location areas is always selected as a compromise.
When using very small location areas, the moving mobile stations
have to contact the network rather frequently to inform the network
about their new location areas. The frequent location updates
reserve a lot of radio transmission capacity, which can then not be
used for transmission of user information. On the other hand, when
using very large location areas, the mobile that is receiving a
call has to be paged from a large area comprising lots of base
stations thus reserving unnecessary amounts of transmission
capacity. Therefore, the optimum size for a location area is a
compromise depending on both the mobility of the subscribers and
the amount of calls coming to the subscribers.
The location can be defined using different levels of accuracy.
When using a packet switched service such as GPRS in the standby
state, the location is tracked with an accuracy of a smaller
location area, i.e. a routing area. This size of a routing area is
smaller than the size of a location area, typically one or a few
cells. When there are packets to be transferred, the service moves
to the active state. For this, the mobile using the service is
paged from the routing area. In the active state the location of
the mobile is tracked with an accuracy of one cell. When there are
no packets to be sent, the service returns to the standby state
after a short delay. When the packet stream continues, the mobile
is paged again from the routing area. The mobile has to be paged a
plurality of times during one connection. Therefore, the number of
pages made during a packet switched connection is generally much
larger than the number of paging messages sent by the RAN when the
mobile is in the idle state of a circuit switched connection. This
is the reason for using smaller locations areas, i.e. routing
areas, in packet switched services.
The location information is needed in the RAN in order to provide
the radio connections for the services provided by the core
networks. Hence, in a system shown in FIG. 1, it is preferable to
store the location information in the RAN. The services offered by
a core network may also depend on the location of the subscriber,
i.e. the subscriber is offered different services in different
service areas. Therefore, the location updates of the mobile
subscriber have to be passed to the core network as well. This
requires signaling and causes an unnecessary load on the I.sub.u
interface.
The problem with the prior art is the handling of location
information between the RAN and the core networks. The objective of
the present invention is to solve this problem. This objective is
achieved using the method defined in the independent claim.
SUMMARY OF THE INVENTION
The basic idea of the present invention is that the definition of
the location area used in the RAN is not necessarily the same as
the specification of the reporting area used when reporting the
location of the mobile to the core network.
The size of the location area is selected preferably by the RAN on
the basis of the services used by the subscriber in order to
optimize the use of radio resources. Preferably, there is a
plurality of location accuracy levels, each having location areas
of different sizes.
A reporting area comprises one or a plurality of location areas.
The size of a reporting area is selected according to the extent of
the accuracy of the location information needed in the core
network. The RAN informs the core network when a subscriber moves
out of his current reporting area.
A service area is the location accuracy level needed for service
management purposes in the core network. It is defined in the core
network but is not necessarily known by the RAN. For example, the
core network may require the subscriber to reauthenticate itself
when entering into a new service area. Also the billing of services
may differ from service area to service area. A service area may
comprise one or a plurality of reporting areas.
If the RAN uses a location area configuration comprising a
plurality of location accuracy levels, the reporting area can be
defined as a location area of a specified accuracy level.
Alternatively, the reporting area can be equal to a service area,
or some specifically specified area. In one embodiment, the service
area configuration is known by the mobile station and the reporting
area configuration is equal to the service area configuration.
According to one embodiment, the core network and the radio access
network negotiate the size of the reporting area prior to the
activation of the service. In addition, the reporting areas can be
renegotiated when the service is in the active state.
BRIEF DESCRIPTION OF THE FIGURES
The invention is described more closely with reference to the
accompanying schematic drawings, in which
FIG. 1 shows a radio access network connected to a plurality of
core networks;
FIG. 2 shows location areas at three different location accuracy
levels;
FIG. 3 shows cells of a mobile telecommunication network belonging
to three different location areas and two different reporting
areas; and
FIG. 4 shows signaling between the mobile station, the radio access
network and the core network.
.Iadd.FIG. 5 shows a service area, reporting areas, and location
areas..Iaddend.
DETAILED DESCRIPTION OF THE INVENTION
According to the invention, the concepts of location area, i.e. the
location information for the need of the radio access network, and
the reporting area, i.e. the location information for the needs of
a core network, are separately defined.
The optimal location area configuration of the RAN basically
optimizes the usage of radio resources. Core networks rely on the
RAN for establishing and optimizing the radio connections. However,
also the core networks need location information for their own
needs. An example of such need is the tracking service used to
track the mobile accurately, e.g. on the accuracy level of one
cell. Another example is the Solsa (Support of Localised Service
Area) service being currently specified by ETSI (European
Telecommunications Standards Institute). Therefore, the RAN
provides the core network the location information of a mobile at
the accuracy of reporting area specified by the core network. To be
able to do this, the radio access network has to track the mobile
at least at the accuracy level of one reporting area even if it
does not optimize the usage of radio resources.
The optimum size for a location area, i.e. the accuracy of location
tracking, depends on the mobility of the subscriber and the amount
of pages made per time unit. The amount of pages is strongly
dependent on the service used. This is due to the different usage
of radio resources for different services. For circuit switched
telephony services provided by the GSM core network, for example,
the RAN has to page the mobile station from its location area
relatively seldom, i.e. only when a mobile station in the idle
state is receiving an incoming call. On the other hand, for packet
switched services the paging occurs relatively often.
For the above-mentioned reason, the RAN has preferably a plurality
of location area levels. An example of an arrangement utilizing a
plurality of location accuracy levels is shown in FIG. 2. In the
figure, three levels are shown. The lowest level L1 corresponds to
large location areas and thus to low accuracy in the tracking of
the mobile station. Mobiles at this level have to be paged from a
large area, i.e. through a large number of base stations. On the
other hand, the subscriber may move around in a relatively large
area without having to make a location update. Therefore, the RAN
places mobiles that move fast or that are paged relatively seldom
at this level.
The middle level L2 has medium size location areas. Here, the
mobiles have to be paged from a smaller area, but more location
updates have to be performed compared to the location area level
L1. This level is suitable for mobiles that are paged more often or
that move less than the mobiles that are placed on level L1.
The highest level of accuracy in location tracking corresponds to
very small location areas. These location areas may be composed of
a single cell, for example. This level is used for services such as
the packet switched services, in which a very high number of pages
is needed or where the mobile for some other reason needs to be
tracked very accurately. An example of such services are tracking
services with the basic objective of giving accurate information
about the location of the mobile.
The reporting area is specified by the core network and the radio
access network is thus informed. The reporting area can
alternatively be negotiated by the radio access network and the
core network. It is preferable to make it possible to change the
reporting area configuration when the service is in an activated
state.
According to one embodiment, of the service area configuration is
known by the mobile station MS which has been assigned the task of
storing information about the service areas of the subscriber, of
initiating a location update procedure when entering a new service
area, and of instructing the radio access network to forward the
new location information to the core network. This situation
occurs, for example, when the localized service area configuration
of a Solsa subscriber is stored in the SIM (Subscriber Identity
Module) card of the subscriber. The service area configuration may
be coded, e.g. by listing the cell identities of the cells
belonging to the special service areas of the subscriber. Based on
this information and the identity information sent by the base
stations, the MS notices the change in a service area when entering
a new one and initiates a location update. As an alternative
implementation the service area configuration may be coded as
geographical coordinate information. In this case the mobile
station has knowledge about its coordinates. This knowledge can be
gathered e.g. by implementing a GPS (Global Positioning System)
receiver in the mobile station or using localizing methods of the
mobile telecommunication system. In this implementation the mobile
initiates a location update when the coordinate information shows
that it has moved to a new service area.
It is to be noted that in this embodiment the service area border
is not necessarily the same as the location area border, and the
service area may thus change within the location area of any
location area level defined in the radio access network. However,
the mobile station also informs the network also when it moves to a
new service area. Thus the RAN tracks the mobile both at the
location accuracy level selected by the RAN and at the service area
level defined by his subscription. The subscriber thus has a
personal location area configuration, the borders of his location
areas being defined by the borders of the location areas of a
location accuracy level and the borders of his personal service
areas. In the context of the location update procedure, the MS
instructs the RAN to report the new information about the location
of the mobile to the core network. In this case, the reporting area
equals the service area configuration known by the mobile station
but not by the RAN.
In the following, we shall study embodiments in which the service
area configuration is known by the core network. The reporting area
can be specified as the location area of a specified location
accuracy level shown in FIG. 2. In this embodiment, the core
network signals to the RAN the location accuracy level to be used,
and the RAN reports to the core network when the mobile moves from
one location area of that accuracy level to another location area
of the same accuracy level. The core network can define the
reporting areas so that a service area is composed of a plurality
of reporting areas, for example.Iadd., as shown in FIG. 5.Iaddend..
This is preferably particularly when the reporting area is
specified as a location area of a location accuracy level. In this
embodiment, the reporting areas in the inner parts of the service
area could be larger than the reporting areas in the border areas
of two service areas. This is easily implemented by specifying the
location areas of different location accuracy levels to be used as
the reporting areas in different parts of the service area.
Alternatively, the CN can inform the RAN of its own service area
configuration, and the RAN reports only the changes in service
area, i.e. the reporting area equals the service area. This
embodiment requires a larger amount of signaling when specifying
the reporting area configuration or when storing the service area
configurations of all the core networks in the RAN. The reporting
area can also be defined using an arbitrary chosen area. The
mapping between the location areas and the reporting areas may be
stored in an external database. If the core network needs no
information about the subscriber's location, the reporting area can
be specified as comprising the whole coverage area of the RAN or by
not requiring that a reporting area be specified. In this case, the
location will never be reported to the core network.
The location area configuration is specified independently by the
radio access network based on the optimization of radio resource
usage and the size of the reporting areas specified. The location
area configuration optimizing the usage of radio resources for a
subscriber may be specified with the help of the past behavior of
the subscriber, i.e. the rate of location updates performed and the
rate of pages made by the radio access network to locate the
subscriber. If the size of the reporting area is smaller than the
optimal size of a location area according to radio aspects, the
location area is equal to the reporting area.
According to the invention, the radio access network tracks the
mobile subscriber with an accuracy of one location area. Changes in
the location area are not reported to the core network unless the
reporting area changes simultaneously. This can be studied with
reference to FIG. 3.
In the figure, a mobile subscriber moves from point A to point C
via point B. On the location accuracy level used for this specific
mobile, the area shown in the figure is divided into three location
areas, LA1, LA2 and LA3. The location areas each comprise a
plurality of cells. For each cell, the base station of the cell
transmits the location area code(s) of the location area(s) the
cell belongs to. If there is a plurality of location accuracy
levels, the cells transmit the location area codes of all the
location areas they belong to at the different accuracy levels. In
addition to the location area configuration, the area is divided
into two reporting areas, Reporting Area 1 and Reporting Area 2.
The mapping of the cells to different reporting areas is only known
by the RAN, and the reporting areas are the location areas of one
location accuracy level, for example. However, it must be noted
that the reporting areas may also be specified in some other way
without losing the general applicability of this example.
In point A, the subscriber is registered in location area LA2
comprising cells 21,22,23,26 and 27 shown in the figure using
backward hatch. The mobile station of the subscriber listens to the
signals sent by the base stations of the RAN and knows the location
area based on the Location Area Code LAC LAC2 transmitted by the
base station of cell 22, the cell the mobile is currently
visiting.
As the subscriber moves onward, he passes point B belonging to
another location area LA1 shown in the figure using a forward
hatch. The mobile station of the subscriber determines this based
on the location area code LAC1 of the new cell 15 now having the
strongest signal at the site of the mobile. Based on the observed
change in the location area code, the mobile station initiates a
location update procedure. In the procedure, the mobile station
initiates a connection with the radio access network to inform it
of its new location area. The radio access network, in turn,
determines that both LA1 and LA2 belong to the same reporting area,
and the reporting area of the mobile phone thus does not change.
Therefore, the core network receives no report as to the new
location of the subscriber.
As the subscriber moves onward to point C, the signal sent by the
base station of cell 33 gets stronger than the signal sent by the
base station of cell 15. Therefore, his mobile starts to listen to
and decode the signal of cell 33. Cell 33 belongs to location area
LA3 shown in the figure using vertical batch. The location area
code LAC3 included in the signal indicates that the subscriber has
again entered a new location area. Therefore, the mobile contacts
the radio access network to inform it of the new location of the
mobile subscriber. The radio access network receives this
information, and, on the basis of the reporting area configuration
defined by the core network determines that the old location area
LA1 belongs to reporting area 1 and the new location area LA3
belongs to another reporting area, reporting area 2. Therefore, the
radio access network sends the core network notification of the new
location of the subscriber.
In response to having received information about the new location
of the subscriber, the core network updates this information into
its memory. If the subscriber has rights to the same services in
both the old and the new reporting areas, the core network returns
the radio access network a message indicating that no changes in
the services offered are to take place. If the rights differ, the
radio access network is informed about the new rights such as
limits as to the bit rates the subscriber may use.
We shall next study what kind of information is transferred in the
location and reporting area updates. An exemplary signaling chart
showing the signaling according to the invention is shown in FIG.
4. The signaling follows the example presented in FIG. 3.
The procedure starts when the mobile station MS at point A of FIG.
3 requests a service provided by a core network by sending the
message K01 to the radio access network RAN. The RAN forwards the
request to the core network CN in the message K02. The core network
consults its subscriber database at stage K03 to check whether the
subscriber is entitled to the requested service. The service is
activated if the subscriber has rights to the service. In addition,
the core network determines the service parameters for the service,
such as the reporting areas to be used, the rights of the
subscriber, e.g. the Quality of Service QoS the subscriber is
entitled to in his present reporting area, and the reporting type,
as well as service characteristics. The service characteristics are
information concerning the service that the RAN is using to
determine the optimal location area configuration from the point of
view of radio efficiency.
The reporting can be either indicative or determining, for example.
Indicative reporting is used when the subscriber has the same
rights in every reporting area, but the core network still wants to
have some information about the location of the subscriber. Such
reporting can be used for tracking services, for example. In the
case of indicative reporting, the radio access network only informs
the core network of the new reporting area of the subscriber. On
the other hand, determining reporting is used when the services the
subscriber is entitled to depend on the reporting area of the
subscriber. In this case, the radio access network has to wait for
the new set of service parameters provided by the core network
before accepting the subscriber's location update for a new
reporting area.
The core network reports the reporting area and other parameters
determined for the connection to the radio access network in the
message K04. The radio access network stores this information in
its memory at stage K05. Based on the characteristics of the:
activated service (or services), the reporting area defined by the
core network (or core networks), and possibly the past behavior of
the subscriber, the radio access network defines the level of
location accuracy used for the subscriber. The RAN defines
identification LA2 of the current location area of the subscriber,
and reports the relevant information to the mobile station in
message K06. At this stage, the mobile station can start using the
services provided by the core network.
After some time, the mobile station has moved to point B in FIG. 3,
i.e. from the first location area LA2 to a second location area
LA1. The mobile station recognizes that the location area
identification it was given is no longer found in the best signal
at the site of the mobile station. Therefore, the mobile station
initiates a location update procedure by sending the radio access
network a location update message K08. In response to having
received the message, the RAN checks at stage K09 the subscriber
information stored in its memory. Based on the check the RAN
determines that the new location area LA2 of the mobile belongs to
the same reporting area as the old location area LA1. Therefore,
the location update will not be forwarded to the core network, but
the RAN determines according to its own criteria, such as radio
criteria, whether the location update should be accepted (ACC) or
rejected (REJ). This information is then returned to the mobile
station in the message K10 to complete the location update
procedure.
The mobile station moves on and arrives at point C in FIG. 3.
Again, it recognizes that it has entered a new location area at
stage K11 and sends the radio access network a location update
message K12. In response to having received the message, the RAN
checks at stage K13 the subscriber information stored in its
memory. Based on the Information, the RAN determines that in
addition to the location area, also the reporting area of the
subscriber has changed. Thus, the RAN sends the core network a
reporting area update message K14. If the reporting is defined as
indicative, the radio access network will immediately send the
mobile station the message K18 concluding the location update
procedure. If the reporting is defined as determining, the radio
access network waits for a response from the core network.
In response to having received the message K14, the core network
stores the new location information and checks the subscriber
information of the subscriber at stage K15. In the new reporting
area, the subscriber may have different service parameters than it
has in the old reporting area. For example, the subscriber may have
rights for both speech and multimedia services in the old reporting
area, but only for speech in the new reporting area. It is also
possible that the subscriber has no rights to any service in the
new reporting area. Additionally, the Quality of Service QoS the
subscriber is entitled to may differ from reporting area to
reporting area. The core network may also request the mobile
station to reauthenticate itself in connection with the service
area update.
Having defined the service parameters, the possible request of
reauthentication procedure, etc., the core network sends this
information to the radio access network in message K16.
The radio access network receives message K16 and modifies the
subscriber information of that subscriber in its memory at stage
K17. The radio access network then defines the identity of the new
location area of the subscriber and sends this information to the
mobile station together with other relevant information concerning
the new reporting and location areas in message K18.
To implement the invention, the radio access network must be
adapted to store information concerning a plurality of location
areas and a reporting area comprising at least one location area,
tracking the mobile station :with an accuracy of one location area,
and reporting to the core network the changes in location with an
accuracy of one reporting area.
Preferably, the RAN is in addition adapted to negotiate the size of
the reporting area with the core network. These arrangements may
either all be centrally implemented in one network element or
distributed over a plurality of network elements of the RAN.
The core network, on the other hand, must be adapted to receive
messages reporting the changes in the location of a mobile station
with an accuracy of one reporting area and to define the current
service area of the mobile station based on the reported location.
The core network is in addition preferably adapted to negotiate the
size of the reporting area with the radio access network. As for
the RAN, these arrangements may either all be centrally implemented
in one network element or distributed over a plurality of network
elements of the core network.
As an advantage of this invention, the accuracy of location
information held in the core networks is optimized for the needs of
the core network, which is independent of the needs of the radio
access network. This reduces signaling over the I.sub.u interface
and unnecessary control operations run in the core network.
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