U.S. patent application number 10/469411 was filed with the patent office on 2004-08-12 for method for determining whether to grant access of a user equipment to a radio access network.
Invention is credited to Persson, Bengt, Stumpert, Martin, Willars, Per.
Application Number | 20040157600 10/469411 |
Document ID | / |
Family ID | 23021311 |
Filed Date | 2004-08-12 |
United States Patent
Application |
20040157600 |
Kind Code |
A1 |
Stumpert, Martin ; et
al. |
August 12, 2004 |
Method for determining whether to grant access of a user equipment
to a radio access network
Abstract
The invention concerns a method for determining whether to grant
access of a user equipment (UE) to a radio access network in a
present position of the user equipment (UE) within a communications
system. The communications system comprises a control node (N1, N2)
handling services for the user equipment (UE) and an access node
(AN1, AN2) controlling the access network. The method is initiated
by receiving a request for service processing for the user
equipment (UE) in the control node (N1, N2) with an identification
of the user equipment (UE). A subscriber group information is
determined for the user equipment (UE) according to the
identification of the user equipment and sent to the access node
(AN1, AN2). Furthermore, an area access information according to
the present location of the user equipment (UE) is determined in
the access node (AN1, AN2). The access granting of the user
equipment (UE) to the radio access network is performed according
to a logical combination of the subscriber group information and
the area access information. A communication network, nodes and
software programs embodying the invention are also described.
Inventors: |
Stumpert, Martin;
(Hochspeyer, DE) ; Persson, Bengt; (Bromma,
SE) ; Willars, Per; (Stockholm, SE) |
Correspondence
Address: |
ERICSSON INC.
6300 LEGACY DRIVE
M/S EVR C11
PLANO
TX
75024
US
|
Family ID: |
23021311 |
Appl. No.: |
10/469411 |
Filed: |
August 28, 2003 |
PCT Filed: |
October 19, 2001 |
PCT NO: |
PCT/EP01/12121 |
Current U.S.
Class: |
455/432.1 ;
455/435.2; 455/436; 455/552.1 |
Current CPC
Class: |
H04W 36/0066 20130101;
H04W 36/30 20130101; H04W 36/10 20130101; H04W 48/04 20130101 |
Class at
Publication: |
455/432.1 ;
455/435.2; 455/436; 455/552.1 |
International
Class: |
H04Q 007/20 |
Claims
1. Method for determining whether to grant access of a user
equipment (UE) to a radio access network in a present position of
the user equipment (UE) within a communications system, the
communications system comprising a control node (N1, N2) handling
services for the user equipment (UE) and an access node (AN1, AN2)
controlling the access network, the method comprising the steps of
receiving a request for service processing for the user equipment
(UE) in the control node (N1, N2) with an identification of the
user equipment (UE), determining a subscriber group information for
the user equipment (UE) according to the identification of the user
equipment, sending the subscriber group information to the access
node (AN1, AN2), determining an area access information according
to the present location of the user equipment (UE) in the access
node (AN1, AN2), and performing the access granting of the user
equipment (UE) to the radio access network according to a logical
combination of the subscriber group information and the area access
information.
2. Method according to claim 1, wherein an operator identification
is determined in the control node (N1, N2)from the identification
of the user equipment (UE) and the subscriber group information is
determined according to the operator identification.
3. Method according to claim 1 or 2, wherein an information on the
roaming agreements for the operators is stored and the subscriber
group information is determined according to the information on the
roaming agreements.
4. Method according to any preceding claim, wherein the subscriber
group information is enclosed in a reply to the request for service
processing.
5. Method according to claim 5, wherein the reply is any message
from a group comprising a common identification message (C), a
relocation request (RR'), a handover request or a bearer assignment
request.
6. Method according to any preceding claim, wherein the determined
subscriber group information is stored and retrieved for a further
determination of an access granting to the user equipment (UE).
7. Method according to any preceding claim, wherein at least one of
the subscriber group information and the area access information is
a bitmap.
8. Method according to claim 7, wherein a logical operation is
performed on the bitmaps and the access granting is determined
according to the result of the logical operation.
9. Method according to any preceding claim, wherein the access
granting is determined in the access node (AN1, AN2).
10. Method according to any of the claims 1 to 9, wherein the
subscriber group information and the area access information are
transmitted to the user equipment (UE) and wherein the access
granting is determined in the user equipment (UE).
11. Method according to any preceding claim, wherein the access
node (AN1, AN2) controls a UMTS radio access network or a GSM radio
access network.
12. Method according to any preceding claim, wherein the access
node (AN1, AN2) is a radio network controller and wherein the
control node is a mobile services switching center or a GPRS
Support Node.
13. Communication network adapted to perform a method according to
any preceding claim.
14. Control node for a communications system with a processing
system adapted to handle services for a user equipment (UE) and
provided with an interface to exchange messages with an access node
(AN1, AN2) and/or with the user equipment (UE), wherein the control
node (N1, N2) is adapted to receive a request for service
processing for the user equipment with an identification of the
user equipment (UE), characterized in that the control node (N1,
N2) is adapted to determine a subscriber group information for the
user equipment (UE) according to the identification and to send the
subscriber group information to the access node (AN1, AN2).
15. Access node for a radio access network of a communications
system with a processing system adapted to determine whether to
grant access of a user equipment (UE) to the radio access network
in a present position of the user equipment and to control the
access and provided with an interface to exchange messages with a
control node (N1, N2) handling services for the user equipment (UE)
and with the user equipment, characterized in that the access node
(AN 1, AN2) is adapted to receive a subscriber group information,
the access node (AN1, AN2) is adapted to determine an area access
information according to the present location of the user equipment
(UE), and to perform the access granting of the user equipment (UE)
to the radio access network according to a logical combination of
the subscriber group information and the area access
information.
16. Program unit comprising code for performing either the steps of
a method according to any of the claims 1 to 12 which are executed
in the access node or which are executed in the control node.
Description
TECHNICAL FIELD OF THE INVENTION
[0001] The present invention relates to a method for determining
whether to grant access of a user equipment to a radio access
network in a present position of the user equipment within a
communications system, the communications system comprising a
control node handling services for the user equipment and an access
node controlling the access network. A communication network, nodes
and software programs embodying the invention are also
described.
BACKGROUND OF THE INVENTION
[0002] The radio access networks of customary mobile communication
systems comprise one or several base stations for the wireless
connection to the user equipment and an access node which controls
the base stations and connects them to the core network of the
communication system. The access node can be for example a base
station controller (BSC) as defined in GSM or a radio network
controller (RNC) for a base station subsystem according to UMTS
(Universal Mobile Telecommunication System) specifications. The
access node therefore administrates the resources of the radio
access system which are required to provide services and
connections to the user equipment which may be a mobile phone or
another wireless terminal, e.g. a personal digital assistant or a
laptop computer.
[0003] Typically the communications system comprises also control
nodes handling services for the user equipment, e.g. for setting up
user originating and terminating connections, short messages or
location data handling of the user equipment. The control nodes are
generally part of the core network of the communication system
which can interconnect different access networks and which may
provide further connections to external networks, e.g. a fixed
telephone system or the Internet. Examples for the control nodes
are an MSC (Mobile Services Switching Center) or an SGSN (Serving
GPRS Support Node with GPRS being the General Packet Radio
Service). The handling of services comprises for example the
provision of routing information in reply to an initial address
message requesting the set-up of a connection to a user equipment
or storing information according to handover procedures of the user
equipment between different radio base stations. For this purpose,
the control node can exchange information with a home location
register (HLR) or a visitor location register (VLR) which store
subscription data as well as the present control node for the user
equipment.
[0004] Especially to save money on network infrastructure, e.g.
when a communication system is updated for a new access technology,
it is advantageous if network operators can share parts of a
network. For example, operators may share a UMTS network while for
other parts of the communication system they may be competitors,
e.g. for networks providing GSM (Global System for Mobile
Communication) connections. Consequently, a wide variety of access
restrictions may apply for home and roaming mobile users throughout
the communication system. Also, different user groups in the home
network may have different subscriptions which only authorize them
for a subset of services. For roaming user equipment in idle mode
location based services implemented in core network nodes can be
used for access granting and restriction. However, no mechanism for
shared networks and mobiles in connected mode exists so far.
Therefore, users in connected mode can presently not be restricted
from entering parts of a mobile communication system which is
forbidden for their subscription.
SUMMARY AND DESCRIPTION OF THE INVENTION
[0005] It is an object of the present invention to obviate the
above disadvantages and provide a method for controlling the access
of user equipment to a radio access system within a mobile
communication system, which is effective and which is easy to
implement.
[0006] According to the invention, the method described in claim 1
is performed. Furthermore, the invention is embodied in a system,
nodes and computer programs as described in claims 13 to 16.
Advantageous embodiments are described in the dependent claims.
[0007] In the proposed method for determining an access grant of a
user equipment to a radio access network in a present position of
the user equipment within a communications system, the
communications system comprises a control node handling services
for the user equipment and an access node controlling the access
network. The control node receives a request for service processing
for the user equipment with an identification of the user
equipment, typically an IMSI (International Mobile Subscriber
Identity) or another identification which may be converted into an
IMSI. The request can for example be an initial address message for
setting up a connection to the user equipment, a set-up request for
a connection originating from the user equipment, a request for
sending a short message (SMS) or a message "relocation
required".
[0008] The control node determines a subscriber group information
for the user equipment according to the identification of the user
equipment, i.e. it performs a classification of the user equipment
identification according to subscriber groups with different access
rights. For example, the classification can be based on stored
roaming agreements for the operator or operators of the
communication system. Particularly, the subscriber group
information can correspond to an indication of a home operator of
the subscriber as well as roaming agreements between the home
operator and one or several operators operating the network which
can be a shared network. Both for a network which is shared and for
a network which is not shared, an operator may have different
roaming agreements which allow access only to specific groups of
home or roaming subscribers.
[0009] The subscriber group information is sent to the access node.
Furthermore, an area access information according to the present
location of the user equipment is determined in the access node,
optionally before reception of the subscriber group information. It
is possible that only a single area access information exists for
the total area covered by the access node or that different parts
of the coverage area have a respective area access information. The
area access information can be for example selected from a memory
of the access node. The access granting of the user equipment to
the radio access network is performed according to a logical
combination of the subscriber group information and the area access
information. The logical combination can be calculated in a
processing system of the access node, e.g. as outlined below.
[0010] The granting or restriction of access can be performed in
different ways. A straightforward alternative is to terminate the
procedure during which the request for service processing was sent
to the control node if the access to the area is forbidden, e.g. to
terminate a connection set-up or a handover. Alternatively or in
addition, the access node can provide a list of allowed or
forbidden cells to the user equipment, i.e. a filtered list of
neighboring cells instead of a list comprising all neighboring
cells. In this case the user equipment can consider only allowed
cells for access and also in signal quality measurements for
handover preparation, i.e. a handover request to a forbidden cell
will not be performed because the signal quality in that cell is
not determined.
[0011] For the proposed method, the amount of signaling of
information between the control node and the access node is low
because only few bits corresponding to the particular user need to
be signaled while information, e.g. tables, required for the
determination of user groups are needed only in the control nodes.
A record representing roaming agreements of the operator can remain
at a single or few locations in the communication system,
especially in the control nodes. This simplifies significantly the
updating of any changes. Also it is not necessary to implement an
analysis function for the user identification in the access nodes
while the existing analysis function in the control node can be
used for determining subscriber groups. Finally, it is possible to
use the proposed method instead of checking whether a user
equipment in idle mode is authorized for access to the
communication system or in case that a corresponding check fails.
The processing load for the checks in the nodes can be reduced in
this way at the expense of increased signaling for requests to
forbidden services. This option is advantageous in case of a small
fraction of requests for forbidden services.
[0012] In a preferred embodiment of the method, an operator
identification is determined in the control node from the
identification of the user equipment and the subscriber group
information is determined according to the operator identification.
In this way, operator agreements can easily be transformed into
data which can be processed in the communication system.
Especially, an information on the roaming agreements for the
operators can be stored, e.g. in the control node or in a central
database accessible to the control node, and the subscriber group
information is determined according to the information on the
roaming agreements.
[0013] The subscriber group information is preferably enclosed in a
reply to the request for service processing. Especially, said reply
can be a common identification (ID) message or a relocation request
message as defined in specification 3GPP 25.413. As the common ID
message is sent at the connection set-up of a UMTS subscriber while
the relocation request message is sent for any further handover in
the connection, it is preferable that the subscriber group
information is enclosed both in a common ID message and a
relocation request message. Else a subsequent handover in a
connection requires additional checks of access restrictions. Both
the common ID message and the relocation request message precede
the radio bearer establishment for the user equipment so that the
handover procedure can be terminated before in case of a restricted
access and unnecessary signaling for bearer establishment is
avoided. However, it is also possible to include the subscriber
group information into a bearer assignment request or a handover
request, e.g. according to specification GSM 08.08 or 3GPP25.413.
As the common ID message is not used in customary GSM networks, a
sending and processing of the message according to UMTS
specifications can be implemented for a GSM network as an
alternative to using the assignment request and/or handover request
messages according to the BSSAP (Base Station System Application
Part) protocol for transmitting the subscriber group
information.
[0014] It is also possible to store the subscriber group
information in the control node or in a user record of a VLR
associated with the control node to avoid a repeated calculation or
in the access node to reduce the signaling. The determined
subscriber group information can then be retrieved for any further
determination of an access granting to the user equipment reducing
the processing and/or signaling load.
[0015] In an advantageous embodiment of the method, at least one of
the subscriber group information and the area access information is
a bitmap which allows an effective transmission and processing of
the information. For example, every bit from a first group of bits
in the bitmap for the area access information can indicate a home
subscriber of an operator, every bit from a second group of bits
can indicate a subscriber of an external operator having a roaming
agreement with a selected operator of the network. One bit can
represent several operators for whom the same restrictions apply.
Further groups of bits in the bitmap for the area access
information may indicate if a user is entitled only for GSM or UMTS
connections or allowed to still further services.
[0016] Preferably, both the subscriber group information and the
area access information are bitmaps and the processing comprises a
logical operation which is performed on the bitmaps. The granting
or denial of an access is determined according to the result of the
logical operation. Determining on the fact whether the bits of the
bitmaps correspond to an allowed or restricted access, the logical
operation can be for example an "AND" or an "OR" operation between
corresponding bits. It is possible to perform different operations
according to the position of a bit and to perform further
processing upon the result of the logical operation.
[0017] The access node can control for example a UMTS radio access
network or a GSM radio access network. In this case the access node
can be for example an RNC (Radio Network Controller) or a base
station controller (BSC). A control node in this case can be a
mobile services switching center MSC for circuit switched
connections, e.g. an MSC comprising the bearer processing for the
connection or an MSC server controlling other nodes, e.g. a media
gateway, handling the traffic bearer. For packet switched traffic
to the user, the control node can be for example a GPRS Support
Node (GSN).
[0018] Preferably, the granting or denial of access is determined
in the access node. This avoids the circumvention of access
restrictions by the user equipment and is especially efficient to
achieve a low amount of signaling in the communication system.
[0019] Alternatively, the subscriber group information and the area
access information can be transmitted to the user equipment and the
access granting is determined in the user equipment. This can avoid
any unnecessary signaling due to access attempts in case of
forbidden access.
[0020] According to the invention, a control node for a
communications system with a processing system is adapted to handle
services for a user equipment and provided with an interface to
exchange messages with an access node or with the user equipment or
with both. The control node is also adapted to receive a request
for service processing for the user equipment with an
identification of the user equipment. The control node is adapted
to determine a subscriber group information for the user equipment
according to the identification and to send the subscriber group
information to the access node.
[0021] An advantageous access node for a radio access network of a
communications system is provided with a processing system adapted
to determine whether to grant access of a user equipment to the
radio access network in a present position of the user equipment,
e.g. in a specific location area. The access node controls the
access of the user equipment to the radio access network, e.g. to
the corresponding target cells. The access node is provided with an
interface to exchange messages with a control node handling
services for the user equipment and with the user equipment.
According to the invention, the access node is adapted to receive a
subscriber group information and to determine an area access
information according to the present location of the user
equipment. It is possible that the same area access information
applies to the total service area of the access node and that the
area access information is stored for this purpose in a memory
accessible to the processing system. The access node performs the
access granting of the user equipment to the radio access network
according to a logical combination of the subscriber group
information and the area access information.
[0022] Both the control node and the access node can be used in any
embodiment of the above method. The steps of the above method
related to the respective nodes as well as the adaptations of the
nodes according to the invention are preferably embodied by
software executed in a processing system of the respective node.
Therefore, the invention is also embodied by a program unit
comprising code for performing either the steps of the above method
which are executed in the access node or which are executed in the
control node. The program unit according to the invention is for
example stored on a data carrier or directly loadable into a
processing system, e.g. as a sequence of signals.
[0023] The foregoing and other objects, features and advantages of
the present invention will become more apparent in the following
detailed description of preferred embodiments as illustrated in the
accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0024] FIG. 1 shows a first scenario for the sharing of networks
between operators
[0025] FIG. 2 shows a second scenario for the sharing of networks
between operators
[0026] FIG. 3 shows a network for performing a method according to
the invention
[0027] FIG. 4 shows a first message sequence according to the
invention
[0028] FIG. 5 shows a second message sequence according to the
invention
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION
[0029] FIGS. 1 and 2 illustrate different shared network scenarios
which are for example suitable for UMTS shared network
solutions:
[0030] In a Geographically Split Network operators each covering
part of a region, for example a country, together provide access in
the whole region.
[0031] In a Common Shared Network, e.g. one, UMTS operator provides
UMTS service for himself and further operators who operate only GSM
networks.
[0032] In a geographically split network, user equipment subscribed
to different operators is allowed access to a UTRAN (UMTS
Terrestrial Radio Access Network) with different access
restrictions for different areas 1, 2, 3 of this UTRAN. An example
situation is shown in FIG. 1, in which operator A and B together to
cover a whole region but compete in a middle area 2 where they both
have coverage. The networks of Operator A and B have an equivalent
access technology in this case, i.e. both provide UMTS access. User
equipment subscribed to operator B is allowed in the whole area 1
of operator A except in the overlap area 2. In the overlap area 2,
access of user equipment subscribed to operator B to operator A is
restricted.
[0033] In the common shared network solution, there are no access
restrictions for the subscribers of the operators A, B, C within a
shared access network 4 but at the borders of the shared network 4,
different neighboring GSM or UMTS cells from the individual access
networks 5, 6, 7 of the operators have to be determined as possible
target for a handover. FIG. 2 illustrates a corresponding example
in which UMTS operator A has allowed access to user equipment from
operators B and C to his UMTS network. When a user equipment UE
moves out of the UTRAN coverage of the shared network 4 into the
GSM region of access networks 5, 6, 7 as indicated by the arrow, a
GSM cell of the respective operator A, B, C should be the target
for a handover. Generally, the situation is further complicated
because roaming restrictions may exist, e.g. between operator C and
operator B.
[0034] The neighboring access networks 5, 6, 7 in FIG. 2 are
described above to be GSM networks but this is not required and
they could also be UMTS networks. Even if there is more than one
UMTS network involved, the common shared network case is different
from a geographically split network for two reasons:
[0035] In a geographically split network, the shared UMTS area is
covered by equivalent access networks each with their own PLMN
(Public Land Mobile Network)-identification, whereas for a common
shared network, the shared UMTS area is covered by one access
network with one PLMN-identification.
[0036] In a geographically split network, access restrictions have
to be considered within the shared area while in a common shared
network, it may be necessary to check access restrictions at the
boundary of the shared area to cells of neighboring networks and
inside the shared area.
[0037] Real configurations may be combinations of these two cases.
For example since equivalent access networks in the geographically
split case will typically also have neighboring networks, the
access granting checks for a common shared network may be also
required at the boundary of the geographically split network.
Therefore, a plurality of cases and situations which may change in
time according to different agreements between the operators must
be considered when granting access of a roaming user equipment to a
network.
[0038] FIG. 3 depicts nodes in a communication system involved in
handling connections with user equipment and determining the
granting of access to an access network which typically comprises
access nodes AN1, AN2, e.g. an RNC or BSC, and radio base stations
BS covering the radio access in different cells C1, C2, C3 through
which a user equipment may roam. The RAN (Radio Access Network) is
the part of the network that is responsible for the radio
transmission and control of the radio connection. The RNC of the
RAN controls radio resources and radio connectivity within a set of
cells while a base station handles the radio transmission and
reception within one or more cells covering a geographical area.
The radio coverage in a cell is provided by radio base station
equipment at the base station site and each cell is identified by a
unique identity, which is broadcast in the cell. There may be more
than one cell covering the same geographical area. The interfaces
between the various nodes are indicated as Iu, Iub, and Iur. The
radio interface is sometimes referred to as the Uu interface.
[0039] A radio access network can comprise several access nodes,
e.g. RNC. Therefore, on a per RAN-UE connection basis, the RNC can
have the roles of an SRNC (Serving RNC) which is in charge of the
connection with the user equipment, i.e., it controls the
connection inside the RAN and provides the connection to the core
network. Alternatively, an RNC may be a DRNC (Drift RNC) for a
connection. In this role the RNC supports the SRNC with radio
resources for a connection with the user equipment that needs radio
resources in cells controlled by the DRNC. The RAN decides the role
of an RNC (SRNC or DRNC) when the UE-RAN connection is established.
Normally, the RNC that controls the cell where the connection to
the user equipment is initially established is assigned the SRNC
role for that connection. As the user equipment moves, the
connection is maintained by establishing radio communication
branches via new cells, possibly also involving cells controlled by
another RNC (i.e., a DRNC). According to implementation, either an
SRNC or a DRNC may be the access node in the method according to
the invention.
[0040] In the core network CN of the communication system, control
nodes N1, N2 handle services like connection requests and handling
of location data for the user equipment UE, both for circuit and
packet switched connections, The control nodes N1, N2 can therefore
be for example an MSC/VLR or an SGSN, either as nodes processing
both the payload and the signaling of the connection or as servers
processing only the signaling and controlling bearer nodes for
handling the payload. A plurality of further nodes FN may be part
of the communication network, the further nodes controlling for
example connections with further fixed or mobile terminals which
may be the target for an originating connection from the user
equipment or the target of a terminating connection. Control nodes
N1, N2 and further nodes FN are adapted to contact a central
location register, e.g. a home location register (HLR) H, holding
an information of the present location of a user equipment,
generally an identification of the respective control node. It is
also possible to send messages between different control nodes N1,
N2.
[0041] The proposed method concerns the signaling between a control
node N1, N2 and an access node AN1, AN2 in connected mode,
especially in shared networks. The control node N1, N2 can perform
an analysis of a subscriber identification, e.g. an MSC or an SGSN
have the possibility to perform an IMSI (International Mobile
Subscriber Identity) series analysis. The outcome of this analysis
is put in a bit map and signaled from the control node N1, N2 to
the access node AN1, AN2 handling the connection, e.g. over the
UMTS Iu interface. The bitmap indicates the subscriber groups which
are applicable for that particular subscriber. The bitmap can be
for example 16 bits long but comprises preferably at least 32 or 64
bits, the actual number of bits being chosen according to the
number of operators considered. A possible usage is that every bit
indicates for a network operator, who shares the network either an
own subscriber or an international roamer (UMTS and/or GSM roamer)
of an operator.
[0042] The information about the operator agreements can be stored
in a database DB, which can either be part of the control nodes CN
or can be contacted by them as depicted in FIG. 3. An example for
the contents of the database DB is shown in FIG. 3a. For every
operator of the communication system A, B, . . . there are entries
with which other operators roaming agreements exist. In the
example, operator A has a roaming agreement with operators X, Y, Z
while operator B has no roaming agreement with operator X and
provides only access to his UMTS cells for user equipment
subscribed to operators Y and Z. To simplify the IMSI analysis, the
operators may be represented in the table by the respective mobile
country codes and mobile network codes.
[0043] The subscriber group information is needed in the access
node to allow or restrict a handover to another cell. Both the
subscriber group information received from control node N1, N2 and
the access information stored for the target cell of the handover
in the access node AN1, AN2 are taken into consideration, i.e. the
access node AN1, AN2 uses the information received from control
node N1, N2 to decide if a handover to a particular cell C1-C3 is
allowed or not. Between a DRNC and an SRNC, the access information
or the subscriber group information may be signaled over the Iur
interface. If a handover for the user equipment is not allowed to a
particular cell, preferably no measurements are done to prepare a
handover towards this cell. In this way, unnecessary signaling is
avoided and the battery life of the user equipment is extended.
[0044] To determine access, the access node AN1, AN2 can apply a
positive or a negative logic for the bitmap indicating the
subscriber group information. For this purpose, the access node
AN1, AN2 has stored information for the cells C1-C3 or location
areas and/or routing areas or for the whole service area, whether
the access for a subscriber group corresponding to a bit in the
bitmap is allowed or forbidden to the respective area. This
information is preferably stored in a second bitmap denoted area
access information.
[0045] For example, six operators A, B, C, D, E and F in a selected
region, e.g. a country have sharing agreements, wherein identical
restrictions apply to all subscribers of operator E and F. In this
case the bitmap for the subscriber group information may comprise
ten bits, E and F being represented by the same bits, the bits
having the meaning
[0046] A/roam to A/B/roam to B/C/roam to C/D/roam to D/E or F/roam
to E or F, i.e. a bit either indicates a home subscriber of the
respective operator or a subscriber of a further operator having a
roaming agreement with the respective operator. Roaming agreements
can especially relate to a particular access network, e.g. only to
UMTS cells. As an example for an international UMTS roamer of
network A, who has also roaming agreement with B, but not with any
of the other operators, the bitmap for the subscriber group
information would be 0/1/0/1/0/0/0/0/0/0.
[0047] For the cell of the access network which is the target for a
handover, a corresponding bitmap for the area access information
defines which user groups have access to the cell. If a cell in the
above example belongs to operator B and B is competing with all
other operators in this cell, the bitmap 0/0/1/1/0/0/0/0/0/0 would
indicate for which subscriber groups access is allowed, i.e. only
for subscribers and international roamers of B.
[0048] To determine whether access to the respective cell is
allowed for a subscriber, a logical AND operation is performed
between both bitmaps, the result being 0/0/0/1/0/0/0/0/0/0 and an
OR operation is performed to the bits of the resulting bitmap,
giving 1 in this case. If the result is 1, a handover to this cell
is possible, i.e. access to the user equipment is granted upon a
request for handover. Else access is restricted and another cell
needs to be selected for a handover. To avoid restrictions in case
of signaling problems, e.g. due to different capabilities of nodes,
access should be granted if the subscriber group information or the
area access information can not be obtained.
[0049] Alternatively, it is also possible to apply a negative
logic, i.e. to indicate those user groups in the bitmap for which
no access is allowed, i.e. if a subscriber group is indicated, the
user equipment does not have access and access is only permitted if
the user does not belong to any restricted group. However,
competing operators frequently have several roaming agreements.
Often the competing operators sharing a network only allow own
international roamers, i.e. user equipment subscribed to foreign
operators with whom roaming contracts exist, but do not allow
roamers of the other operators with whom they share the network. In
this case an international roamer could have roaming agreements via
his home operator with both operators A and B. Applying negative
logic, the cell of operator A would be restricted to subscribers of
the foreign operator with a roaming agreement of operator B. In
this case, access should be allowed while a specification, e.g. of
3GPP, may require that access is forbidden if a restriction applies
to any of the subscriber groups, i.e. access would be forbidden for
the subscriber although he holds a roaming agreement with operator
A as due to one restricted group, the access is not allowed.
Therefore, additional operations on the bitmaps are required to
consider such cases and allow access.
[0050] For the generation of the bitmap, information about the
roaming agreements for all operators sharing a network is stored in
a control node N1, N2 in the core network, e.g. in an MSC or SGSN.
Alternatively or for updates, a server in the communication network
can provide access to information on the roaming agreements for
downloading of the corresponding data by the control node N1, N2.
When a request for a handover or another service like a connection
set-up or sending a short message (SMS) is received for a user
equipment, the control node N1, N2 performs an analysis of the
subscriber identification, e.g. an IMSI series analysis for
determining to which operator a user equipment is subscribed.
[0051] In GSM and UMTS networks this is possible according to the
definition of the IMSI comprising a mobile country code (MCC) and a
mobile network code (MNC) in addition to the mobile subscriber
number (MSN), i.e. IMSI(max 15 digits)=MCC(3 digits)+MNC(2 or 3
digits)+MSN In this way, the first digits of the IMSI indicate the
operator. With this knowledge and the stored representations of the
roaming agreements, the MSC sets the bitmap to indicate the
subscriber group information of the subscriber, e.g. indicating if
it is an own subscriber, for each of the operators sharing the
network and indicating if the home operator of the subscriber has
roaming agreements with any of the operators sharing the network,
for each operator sharing the network.
[0052] It should be noted that in GSM and UMTS networks, location
area identifications comprise bits corresponding to MCC, MNC,
location area code (LAC) while the bits of cell identifications
correspond to MCC, MNC, LAC and cell identity. According to this
definition, in one location area there are only cells of one
operator.
[0053] For signaling the bitmap indicating the subscriber group
information to the access node AN1, AN2 which performs the logical
operation to determine the access granting or restrictions, the
Common ID message and the Relocation Request message according to
GSM and UMTS specifications are preferable messages.
[0054] The purpose of the Common ID message in networks according
to the state of the art is paging coordination in an RNC of the
access network, i.e. to avoid unnecessary paging if a user
equipment can have several connections, e.g. a circuit switched
connection and a packet switched connection. The Common ID message
is always sent to the RNC after a subscriber is authenticated and
comprises the IMSI in addition to the bitmap according to the
proposed method. If selective authentication is used, i.e. an
authentication procedure is omitted in a message flow for resource
saving, the Common ID message is sent after the point in time where
the authentication would be done. This applies for mobile
originating or mobile terminating connections and services as well
as for SMS and USSD (Unstructured Supplementary Service Data)
signaling.
[0055] After the first service or handover took place, the new
access node AN1, AN2 may initiate a further handover. To allow the
selection of an appropriate cell, the new access node AN1, AN2 is
also provided with the subscriber group information. For this
purpose, the Relocation Request message according to UMTS
specifications is advantageous.
[0056] FIGS. 4 and 5 show examples of signaling procedures in a
method according to the invention. In both figures, examples for
the devices involved in the signaling are indicated at the top of
the vertical lines. Double-headed arrows indicate procedures which
comprise two or more messages between the involved devices. More
detail on the messages can be found in the 3GPP specifications of
the 3.sup.rd Generation Partnership Project, especially in
specification 3GPP 25.413 V4.1.0.
[0057] FIG. 4 shows a signaling for a mobile terminating call which
is initiated with an initial address message IAM from a transit
switching center (TSC) or a gateway MSC (GMSC). After a paging
procedure P, P' an authentication A, A' of the user equipment is
performed followed by a mode procedure M, M' for setting
transmission mode parameters. Then the common ID message C is sent,
comprising the subscriber group information as described above as a
bitmap. Furthermore, the common ID message C indicates to the RNC
that a connection to the user equipment already exists and a
paging, e.g. due to a further connection request from an SGSN, is
not required.
[0058] In an alternative embodiment of the invention, the
subscriber group information can be included in the direct transfer
message D initiating the connection set-up procedure S, S'. The
advantage of the former option is that it requires less signaling
in case of restricted access, i.e. the set-up is terminated
earlier. Furthermore, the common ID message C is sent from the MSC
to the RNC both for a mobile originating and a mobile terminating
connection. In contrast, the direct transfer message D and the
corresponding confirmation D' are sent in the opposite direction
between RNC and MSC for a connection originating from the user
equipment UE. Therefore, a subdivision between mobile originating
and terminating connections would be required to determine whether
the subscriber group information has to be included in the direct
transfer message D or the confirmation D'. Finally, the further
call set-up S, S' proceeds if the processing of the subscriber
group information and the area access information has the result
that the user equipment is allowed for connections or services in
the radio access network. Else the procedure is terminated.
[0059] In a further alternative embodiment, the subscriber group
information can be included in an assignment message requesting
bearer establishment during the connection set-up procedure S, S'.
This alternative has the advantage that the assignment message is
always sent form the control node to the access node. However, if
the procedure is terminated at this point in time, much unnecessary
signaling is performed.
[0060] For a subsequent handover during the connection from a
source RNC to a target RNC, an advantageous message flow is
depicted in FIG. 5. The message flow is initiated by a message
"relocation required" RR from the source RNC presently controlling
the radio connection to the MSC controlling the connection for the
access network. In turn the MSC sends a message "relocation
request" RR' to the target RNC which can be determined for example
due to transmitted measurement results for the connection quality
form the user equipment.
[0061] According to the invention, the bitmap representing the
subscriber group information is included in the relocation request
RR'. The further relocation procedure R, R' proceeds only if the
processing of the subscriber group information and the area access
information stored in the RNC has the result that the user
equipment is allowed for connections or services in the present
location by the radio access network. Else the procedure is
terminated. In this case the a different target RNC needs to be
selected and a further relocation procedure initiated.
[0062] Both after the message flow in FIGS. 4 and 5, preferably the
access node provides a filtered list of neighboring cells to the
user equipment to avoid that quality measurements on restricted
cells are performed for further handover preparation, i.e. cells
can be removed from a list of neighboring cells if access will not
be granted. For any subsequent handover, restricted cells can be
ruled out in this way as possible targets, reducing battery
consumption in the mobile phone and avoiding unnecessary
signaling.
[0063] If the access restriction is performed by cell filtering, a
list of neighbor cells adapted to the specific user equipment's
subscription can be provided. To filter the list of all neighbor
cells down to those cells appropriate, again subscriber group
information is considered along with area access information about
the neighbor cells. The home network of the mobile can be
determined from the IMSI. In addition, the network to which a
neighbor cell belongs is part of the UTRAN cell identity stored in
the DRNC and transferred to the SRNC.
[0064] In an example method for implementing the invention, based
on available mobile subscriber information, it is determined which
networks identified by PLMN codes represented by mobile country
code and mobile network code may be accessed by the subscriber. A
filtering of the list of neighbor cells is performed to limit the
list to those cells consistent with the user's subscription and the
filtered neighbor cell list is sent to the mobile using standard
signaling.
[0065] The control node determines the allowed networks of the
subscriber, e.g. as a list of MCC+MNC or as subscriber group
information represented by a bitmap, and passes the allowed
networks to the SRNC over the Iu interface in the common ID
message. The SRNC can forward the allowed networks over the Iur
interface to the DRNC which performs filtering. If the filtering is
performed in an SRNC, the control node again passes the allowed
networks or subscriber group information to the SRNC over the Iu
interface in the common ID message. The DRNC sends the full list of
neighbor cells over Iur and the SRNC performs filtering of the cell
list received from the DRNC.
[0066] In principle, the combination of the subscriber group
information and the area access information can also be done in the
user equipment or in the control node. For example, an alternative
solution uses national roaming restrictions in the MSC which also
administers the restricted location areas per subscriber group. The
method for access granting is then implemented in the MSC and
location areas are ruled out for handover, if access is not allowed
for the subscriber. Then only those location areas which are
allowed for the user equipment are indicated to the RNC to prepare
the handover. However, the proposed solution is especially resource
efficient and avoids unnecessary signaling.
[0067] It is possible that an inter-MSC handover is required during
a connection from an anchor MSC outside the communication system to
a target control node in the system. The anchor MSC may be a
control node not adapted to perform the proposed method or lacking
information on the roaming agreements to determine the subscriber
group information. According to UMTS and GSM specifications, the
anchor control node outside the shared communication system
processes any services for the user equipment while the target
control node adapted to the proposed method would only relay
messages to the access node. In this case, the target control node
can amend the relayed messages by the subscriber group information
or signal the subscriber group information to the anchor control
node of the inter-MSC handover for inclusion into messages.
[0068] The above embodiments admirably achieve the objects of the
invention. However, it will be appreciated that departures can be
made by those skilled in the art without departing from the scope
of the invention which is limited only by the claims.
* * * * *