Note: Descriptions are shown in the official language in which they were submitted.
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A MOBILE STATION, EQUIPMENT FOR CONNECTION TO A MOBILE
STATION, SWITCHING SYSTEMS IN MOBILE COM~SUNICATIONS
SYSTEMS AND MOBILE COMMUNICATIONS SYSTEMS
FIELD OF INVENTION
The present invention relates to a mobile station, equipment
connected to a mobile station, a switching system in a mobile
communications system with connection to an external node,
and to a method relating to a mobile communications system
and in particular to a plurality of transactions that take
place in parallel to a mobile station.
DESCRIPTION OF THE BACKGROUND ART
There are known to the art a number of solutions which enable
mobile communications system to set up several parallel
transactions, i.e. simultaneous transactions, with a mobile
station. By transaction is meant both a circuit switched data
connection and the transmission of user data through the
medium of a non-circuit-switched data transmission service.
In addition to circuit switched data connections, which are
typically used for speech connections, the GSM system also
includes the SMS service and a group of services designated
supplementary services. This service group includes a USSD
(Unstructured Supplementary Service Data) service. USSD is
standardised and was originally intended for use in
transmitting data between a mobile station and a node in a
switching system SS with a GSM network. Initially, it was
only possible to set up one USSD transaction at a time with
the mobile station MS.
U.S. 5,752,188 describes a solution which enables USSD to be
used also for transmitting data between the mobile station
and a USSD service node located outside the GSM network.
Other service nodes can be connected to a USSD service node.
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These other service nodes allow the mobile station access to
a number of applications through USSD transactions. The
solution gives no limitation as to the number of USSD
transactions that are set up with the mobile station.
SUt~IARY OF THE INVENTION
The present invention addresses a problem where a transaction
is set up with a mobile station regardless of whether or not
the user of the mobile station wishes the transaction to be
established. Undesired information transmitted via the
transaction places the user physically under stress. He/she
will be particularly stressed by information from different
sources obtained via different parallel transactions.
One problem is that a transaction can impair or degrade the
quality of another transaction that is sent to the mobile
station at the same time as the former transaction. It occurs
that transmission resources are stolen from one transaction
and given to another, for instance a speech connection is
impaired by parallel USSD transaction.
Accordingly, one object of the present invention is to enable
a user of the mobile station to prevent a transaction in
advance and in particular to prevent several transactions
with the mobile station from progressing at one and the same
time. Another object is to ensure that the quality of a
circuit switched data connection will not be impaired or
degraded because other transactions are ongoing against the
wishes of the user.
The aforesaid problems are solved by a method pertaining to a
mobile communications system wherein a user of a mobile
station expresses beforehand whether or not he/she is
prepared to allow a requested transaction to be set up. When
receiving a request for the connection of a transaction with
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the mobile station, the user admission or permission is
checked and the requested connection is made in accordance
with this admission.
The aforesaid problems are also solved by a mobile station
that includes means for registering the user admission as to
whether or not the transaction may be set up, means for
checking whether or not a requested transaction is in accord
with the user's admission, and means for preventing a
requested transaction when said transaction is not permitted.
The aforesaid problems are also solved with a switching
system that is connected to at least one base station system
and thereby connected to a mobile station, and a connection
to a service node. The switching system also includes means
for receiving from the service node a request to set up a
transaction with the mobile station, and means for fulfilling
the request. The switching system includes means for
registering the user admission, or permission, to set up a
transaction and means for checking the admission in respect
of a request for a new transaction, wherewith the transaction
is prevented if it is not in accord with the user admission.
These solutions include a number of different embodiments.
The permission given by the user may be such as to allow a
USSD transaction to be set up only if no speech connection,
i.e. circuit switched data connection is ongoing.
Alternatively, the permission given may stipulate that only a
certain.. number of transactions may be ongoing in parallel.
Another alternative is that a transaction intended for a
given application will only be inhibited from or given as one
of a number of allowed transactions on the basis of its
intended application.
One advantage afforded by the invention is that the user of
the mobile station can limit beforehand the number of
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parallel transactions that can be undertaken with the mobile
station. In this regard, the user limits the number of
information sources that send information to the mobile
station simultaneously, and therewith avoid mental strain.
The user may also, or alternatively, prevent transactions
being set up on the request of certain applications, or
alternatively only permit transactions on the request of
certain applications. The user will hereby stop in advance
the transmission of undesired information.
Another advantage afforded by the invention is that a circuit
switched data connection can be used without impairing the
quality of other transactions with the mobile station. For
instance, the invention prevents parallel USSD transactions
that would otherwise take transmission capacity from the
circuit switched data connection. Results of measurements
made in this respect show that about 15-20% of speech frames
sent to a given mobile station in a GSM network are degraded
by parallel ongoing USSD transactions. The percentage of
degraded or impaired speech frames should be restricted to
about 1-2% in order for acceptable speech quality to be
obtained.
The invention will now be described in more detail with
reference to exemplifying embodiments thereof and also with
reference to the accompanying drawings.
BRIEF DESCRIPTION OF T8E DRAWINGS
Figure 1 is a view of a cellular mobile communications system
including nodes.
Figure 2 is a flowchart illustrating an inventive method.
Figure 3 is a block schematic illustrating nodes included in
the switching system (not complete).
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Figure 4 is a block schematic illustrating nodes that are
active in setting-up a USSD transaction.
Figure 5 illustrates the principle of a permission
registering data structure.
DESCRIPTION OF PREFERRED E~ODIMENTS
A number of embodiments of the present invention are
described below with reference to a GSM network by way of
example. Figure 1 is a view of the known mobile
communications system PLMN GSM. The GSM network PLMN includes
a mobile station MS, a number of radio base transceiver
stations BTS1-BTS2, two base station controllers BSC1-BSC2, a
mobile services switching centre MSC, a Gateway Mobile
services Switching Centre GMSC, a Visitor Location Register
VLR, and a Home Location Register HLR. Each radio base
station BTSI-BTS2 is connected to a base station controller
BSC1-BSC2, which in turn is connected to the mobile services
switching centre MSC. The mobile services switching centre
MSC is connected to the visitor location register VLR and to
the gateway mobile services switching centre GMSC. The
gateway switching centre GMSC is connected to the home
location register HLR.
The mobile station MS is connected by radio to the radio base
station BTS1 that serves a cell C1 within which the mobile
station MS is situated at that moment in time.
The gateway mobile switching centre GMSC is connected to
other telephone networks (not shown in Figure 1) and to a
USSD service node USSDgw.
Transactions in the form of speech connections TCH or SMS
transactions can be set up between the mobile station MS and
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telephone network terminals, through the medium of the
gateway mobile switching centre GMSC. USSD transactions
USSD1, USSD2 are set up between the mobile station MS and the
USSD service node USSDgw.
-
Three types of transactions are defined in the GSM system.
The first of these types of transaction is a traditional
circuit switched data connection TCH used typically for
speech connections. A connection is set up through the GSM
network or duplex connection TCH in this respect.
The second type of transaction is an SMS transaction. An SMS
transaction is a one-way connection, although the connection
can be chosen to or from the mobile. The transaction is
effected via an SMS service node outside the GSM network PLMN
(not shown in the Figure). This connection is not a "usual
connection" but is one in which the user data is transferred
transparently by protocol in the GSM network PLMN that
normally handles signalling.
The third type of transaction is a group of services defined
under the collective name of "Supplementary Services". This
group includes a service USSD, meaning Unstructured
Supplementary Data. Similar to the SMS transaction, user data
is transmitted transparently with signalling protocol within
the GSM network PLMN. As opposed to an SMS transaction, a
USSD transaction takes place in the form of a dialogue in
which an answer is given to a question included in the
transaction, for example.
These three types of transaction can be carried out with the
mobile station MS in parallel, i.e. simultaneously. Solutions
are also found for setting-up several USSD transaction in
parallel. The standardising commission ETSI is in the process
of standardising the implementation of how several USSD
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transactions can set up simultaneously between the mobile
station MS and one or more USSD service nodes USSDgw.
Figure 1 illustrates a circuit switched transaction TCH and
two USSD transactions USSD1 and USSD2 that are ongoing
simultaneously with the mobile station MS. Figure 1 does not
show the external telephone network to which the circuit
switched transaction continues. The two USSD transactions
USSD1, USSD2 take place between the mobile station MS and the
USSD service node USSDgw. A number of applications AP are
connected to the USSD service node USSDgw. The applications
AP can either be implemented in the USSD service node or in
own service nodes that are connected to the USSD service
node. The applications use the USSD service node for
information transfer with the mobile station MS. Another
service node WAPgw for Internet protocol is also connected to
the USSD service node. The mobile station MS obtains access
to information on the Internet, via the second service node
WAPgw. The second service node WAPgw ensures that the
information will be delivered and presented in a manner
optimal for the mobile station.
The USSD transactions, USSD1, USSD2, are transmitted on the
radio connection of a radio channel designated FACCH (Fast
Associated Control CHannel). The circuit switched connection
TCH is transferred on the radio connection of a traffic
channel TCH. The FACCH channel is set up only when data to be
transmitted via this channel is found, and when set up then
steals transmission capacity from the traffic channel. The
transmission of the two USSD transactions USSD1, USSD2 will
considerably impair the quality of user data that has been
transmitted by the traffic channel. When speech is
transmitted by the traffic channel, a certain degree of
speech impairment or degredation can be corrected with the
aid of coding. When the speech impairment is greater than a
given threshold value, the fault cannot be corrected by
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coding and the speech will be so poor that the receiver will
be unable to understand what is said.
The present invention enables the user of the mobile station
MS to prevent a transaction USSD1, USSD2 being set up in
parallel with a circuit switched data connection TCH, or to
limit the number of transactions TCH, USSD1, USSD2 that can
be set up with the mobile station MS, or to release an
ongoing transaction USSD1, USSD2 when a circuit switched data
connection TCH is established.
Figure 2 is a flowchart illustrating the method steps of
checking user admission when a request for connecting a
transaction USSD1, USSD2 is received.
In a first step S1, a number of parameters are initiated to
indicate a certain value. This value is determined by the
user of the mobile station MS and the parameters together
constitute the user's permission, i.e. user admission, to set
up a USSD transaction. A first of the parameters UPAF denotes
whether or not the admission check has been activated. In
step Sl, the parameter UPAF is set to indicate that the
admission check is on.
A second of the parameters, TCHACF, is set to indicate
whether or not the establishment of a USSD transaction is
allowed or not allowed when a circuit switched data
connection has already been established.
A third parameter NoNP is set to indicate whether or not a
request for a USSD transaction intended for an unknown '
application is in accord with the user admission or not. If
this is given in the request, it will be in the form of the
identity "NEI" (Network Element Identifier) of the USSD
service node USSDgw and its port address . The port address,
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or gateway address, in combination with NEI corresponds to a
given application.
A fourth parameter MaxNo is set to indicate the maximum
number of USSD transactions that are permitted to take place
in parallel, i.e. simultaneously.
The user may include a black list or white list in addition
to these parameters, if he/she so desires. The black list
will include applications for which a transaction request is
inadmissible. The alternative white list includes
applications for which a transaction is admissible solely if
the intention of the transaction is an application included
in the white list.
On a later occasion there is received a request for a USSD
transaction, in accordance with step S2.
In step S3, a check is made to ascertain whether or not the
admission control has been activated or not. This state of
the control is given by the parameter UPAF. If the admission
control is not activated, the transaction is set up in an
earlier known manner in accordance with step 513. On the
other hand, if the admission control is on, the control
continues by checking in a following step S4 that the
requested transaction is in accord with the registered
permission.
In step S4, a check is made to ascertain whether or not the
requested USSD transaction may be set up if a circuit
switched data connection is already ongoing. This is
indicated by the parameters TCHACF. If set to "ON", a check
is made to ascertain whether or not a circuit switched data
connection is ongoing, according to step S5. If a circuit
switched data connection is ongoing, the requested USSD
transaction is stopped, in accordance with step 519. If the
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USSD transaction may be set up despite an ongoing circuit
switched data connection, i.e. no to the question raised in
step S9, or if no circuit switched connection is ongoing,
i.e. no to the question raised in S5, the control continues
in accordance with step S6.
In step S6, a check is made to ascertain whether or not the
received request for a USSD transaction discloses the
intended application for the transaction according to the
request, and if the application is disclosed the application
is also read. If such is the case, the application will be
disclosed with the address of the USSD service node USSDgw on
the form "NEI" (Network Element Identifier) plus port which
together with NEI corresponds to a certain application. If
the application is not stated, a check is carried out in step
S7 to ascertain whether or not a request intended for an
unknown application is in accord with the admission. This is
indicated by the parameter NoNP and the transaction is
terminated in accordance with step S14 if the transaction
according to the request is not allowed. On the other hand,
if the answer to the question raised in step S7 is yes - a
transaction intended for unknown application is allowed - a
further check is carried out in accordance with step S12. If,
on the other hand, the application is indicated in the
request, step S6 is followed by step S8.
In step S8, a check is made to ascertain whether or not a
Black list is found. If the answer is yes - a black list
exists -~a check is carried out in step S10 to ascertain
whether or not the application for the requested USSD
transaction is included on the black list. If the answer is '
yes also to the question raised in step S10, i.e. the
transaction according to the request is not allowed because
of the application intended, the transaction is terminated in
accordance with step S14.
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On the other hand, if the answer to the question in step S10
is no, i.e. the transaction is not blocked because of the
intended application, a further check is carried out in
accordance with step S12.
On the other hand, if the answer to the question in step S8
is no - i.e. no black list exists, a check is made in step S9
to ascertain whether or not there exists a white list. If no
white list exists, i.e. the answer to the question is no, a
further check is carried out in accordance with step 512. On
the other hand, if a white list exists, a check is carried
out in step S11 to ascertain whether or not the intended
application of the transaction according to the request is
included in the white list. If the answer to the question is
no, the application in the request is not included in the
white list, the transaction is terminated in accordance with
step S14. On the other hand, if the application is included
in the white list, i.e. yes to the question raised in step
S11, step S12 is carried out.
In step 512, a check is made to ascertain whether or not the
number of transactions ongoing with the mobile station MS is
beneath the maximum number of permitted USSD transactions.
The maximum number of USSD transactions that are permitted to
be ongoing simultaneously is indicated by the parameter
MaxNo. If the answer is yes, i.e. the number of USSD
transactions is less than the maximum permitted number, the
transaction is set up in accordance with the request in a
conventiopal manner; see step S13.
On the other hand, if the answer to the question in step S12
is no, i.e. the number of ongoing USSD transactions is not
fewer than the maximum permitted number, the requested USSD
transaction is terminated in accordance with step 514.
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As an alternative to allowing parameter UPAF to indicate
solely whether the admission control is activated or not, as
in the above example, there is defined a further indication
"USSD transaction allowed". The flowchart in Figure 2 is
extended with a further step after step S3, control: Is USSD
transaction allowed? If the answer is yes, the control
carried out in accordance with step S4 continues in the same
way as before. If no, i.e. no USSD transaction is allowed,
the requested USSD transaction is terminated according to
step S14.
Several different nodes in the GSM network PLMN may
alternatively be chosen to register the state of the user and
to check this state in conjunction with a connection request.
In an inventive mobile station MS, the user admission is
registered and an admission control carried out in accordance
with the flowchart of Figure 2.
As with conventional mobile stations, the inventive mobile
station includes a display screen and keypad with which the
user controls the mobile station. As with conventional mobile
stations, the inventive mobile station includes a function
with which the number of ongoing transactions USSDl, USSD2,
TCH can be counted.
The mobile station MS also includes a register for storing
those parameters that indicate user admission to USSD
transactions. The mobile station MS also includes a function
for controlling user admission when a request for a USSD
transaction has been obtained, in accordance with the method
described with reference to Figure 2.
The mobile station MS receives a request for a USSD
transaction in a message "Register" over the FACCH channel.
The mobile station MS answer with a message "Facility". Both
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of these messages includes a USSD component that contains
data for the USSD transaction. If the mobile station MS
terminates the transaction, this is indicated by the USSD
component in the message "Facility". This is earlier known.
In the earlier known message there is defined a new reason
for terminating the USSD transaction. This new reason is "the
USSD transaction is forbidden by the user".
The user of the mobile station MS initiates the admission
parameters, i.e. registers the form of admission he desires,
through the medium of the mobile station keypad and
instructions on the display screen of the mobile station MS.
The already known control functions of the mobile station MS
handle instructions from the user and in this case cause the
admission parameters to be registered. According to GSM
standards, a mobile station MS is comprised of mobile
equipment and a SIM card. The register containing admission
parameters may either be inserted into the mobile equipment
or into the SIM card. The SIM card is supplied by the
operator of the GSM network, who has set the admission
parameters beforehand in a first state when these parameters
are stored in the SIM card.
As an alternative to allowing the mobile station MS to handle
registration and control of the user admission, the
registration and control may be handled by the switching
system. The switching system SS and its nodes are defined in
GSM standards. Figure 3 shows those nodes of the switching
system SS that are significant to the present invention. The
switching system SS in Figure 3 thus includes the switching
centre plus the visitor location register MSC/VLR, the
gateway mobile switching centre GMSC and the home location
register HZR. These nodes are connected to each other and to
external nodes in the manner described above with reference
to Figure 1.
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In order to simplify the following description, it is assumed
that the USSD service node USSDgw is connected directly to
the home location register HLR as shown in Figure 4.
Figure 9 illustrates a second service node AS with
application AP. An arrow A1 indicates that the USSD service
node USSDgw is contacted by the second service node AS which
requests permission to set up a USSD transaction USSD1, USSD2
with the mobile station MS. The mobile station MS is
specified by its identity, designated MSISDN. The USSD
service node USSDgw then sets up a transaction with the home
location register HLR by sending a USSD request to the home
location register in a message "TCAP-BEGIN". This message is
sent in accordance with the protocol MAP (Mobile Application
Part) and is indicated by an arrow A2 in Figure 4. When the
home location register HLR has received this USSD request,
the home location register translates the identity MSISDN of
the mobile station MS to the corresponding identity
designated IMSI used in the GSM network PLMN. The home
location register HLR also checks the identity of the
switching centre plus visitor location register MSC/VLR that
serves the mobile station MS at that moment in time and sets
up a USSD transaction with this switching centre/visitor
location register MSC/VLR. The USSD transaction is set up by
the home location register HLR, by sending a USSD request to
the switching centre/visitor location register MSC/VLR in a
message "TCAP-BEGIN" shown by an arrow A3 in Figure 9.
The method of setting up a USSD transaction described above
is known ~to the art and is described more explicitly in the
specification GSM 09.02 and GSM 03.90.
When a conventional switching centre/visitor location
register MSC/VLR has received the message "TCAP-BEGIN", it
initiates procedures for mobility management and radio
resource management, for instance for calling the mobile
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station MS and for allocating signalling capacity. These are
used to set up the USSD transaction to the mobile station MS.
The USSD transaction request is forwarded to the mobile
station MS and when a reply has been obtained, the reply is
forwarded to the second service node AS via the USSD service
node USSDgw. For each string of user data that is
subsequently sent via the USSD service node USSDgw, it then
awaits a reply. A USSD transaction can therefore be likened
to a dialogue.
According to one embodiment of the present invention, the
switching centre/home location register MSC/VLR checks that
the requested USSD transaction is in accord with the
registered admission, before starting the mobility management
and radio resource management procedures.
The mobility management and radio resource management
procedures are not started if the request is not in accord
with the registered admission. Instead, an error message is
sent back to the USSD service node USSDgw from the switching
centre/visitor location register via the home location
register HLR. It is already known to send the error message,
but a new error-cause "USSD transaction inhibited by user" is
included in the error message. The error message is
transported in a component "TCAP Error".
The inventive mobile switching centre/visitor location
register MSC/VLR includes a user admission storage register..
The mobile switching centre/visitor location register MSC/VLR
also includes a function for checking this admission upon
receipt of a request for setting up a USSD transaction, in
accordance with the inventive method.
A known mobile switching centre/visitor location register
MSC/VLR is able to count the number of transactions ongoing
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with the mobile station MS. This function is used when the
admission states that only a limited number of parallel
transactions may be set up with the mobile station MS. A
known mobile switching centre/visitor location register
MSC/VLR also has a function for checking the type of
transaction that might have been set up. Thus, setting-up of
new transactions can be inhibited when the admission states
that no further transactions may be set up when a circuit
switched data connection has already been established.
Information relating to the mobile station MS is registered
in the mobile switching centre/visitor location register
MSC/VLR in connection with said mobile switching
centre/visitor location register MSC/VLR serving the mobile
station MS. A GSM network will normally include a plurality
of switching centres and associated visitor location
registers, although only one will serve the mobile station MS
at any one time. When the switching centre/visitor location
register MSC/VLR accepts the mobile station MS for service,
data relating to the mobile station MS is downloaded in the
mobile switching centre/visitor location register MSC/VLR
from the home location register HLR, in which mobile station
MS information is always registered.
In conjunction with a change of serving switching
centre/visitor location register MSC/VLR, it is known to
transfer mobile station data from the home location register
HLR to the mobile switching centre/visitor location register
MSC/VLR. This is effected by a well-known procedure "Update
Location" with a function "Insert subscriber Data". Similar
to other subscriber data, the user admission shall also be '
registered in the home location register HLR and transferred
to the mobile switching centre/visitor location register
MSC/VLR by the procedure "Update Location" and the function
"Insert Subscriber Data".
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Figure 5 illustrates schematically the data structure for
user registered admission. A corresponding data record P is
found for the mobile station MS. The data record P of the
mobile station MS is identified by one of its two identities
MSISDN and IMSI. Chosen values of the parameters UPAF, TCHACF
and NoNp are registered in the data record. The data record P
also includes a list L which contains an indicator that shows
whether the list is a black list or a white list. The list L
then includes a number of NEIs each being an address to a
USSD service node USSDgw. A number of port addresses are also
defined in the list. Each port address in the list is
associated with an NEI and together indicate a given
application.
In conjunction with changing a switching centre/visitor
location register MSC/VLR serving the mobile station MS, a
copy of the data record P is sent from the home location
register to the mobile switching centre/visitor location
register MSC/VLR.
There are several ways in which the user can register its
admission in the home location register. The simplest way is
to inform the GSM network operator as to which admission is
desired, whereafter the operator sets the parameters to
indicate the admission, via a man machine interface (MMI).
Other solutions enable the user to set admission parameters
in accordance with desired admission, via the mobile station
MS. One such solution involves setting up a USSD transaction
with HLR~ and transferring desired USSD admission to HLR,
where the parameters are registered. Other solutions involve
providing HLR with an interactive voice control or a WWW
interface, with which the mobile station user can cause the
home register HLR to register desired admission.
Alternative to the mobile switching centre/visitor location
register handling the control of the user admission upon
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request of a USSD transaction, the home location register may
handle the control. The home location register uses control
functions corresponding to those used in the mobile switching
centre/visitor location register. One difference, however, is
that the home location register HLR contains no information
concerning transactions that are ongoing with the mobile
station MS. Consequently, a requested USSD transaction cannot
be inhibited because a certain number of transactions or a
circuit switched data connection are/is in progress. However,
when the home location register is allowed to carry out said
control, it is unnecessary to copy the admission parameters
to the mobile switching centre/visitor location register
MSC/VLR.
The mobile station MS may be provided with connected
equipment. The mobile station MS and the connected equipment
together form a mobile terminal. The connecting equipment is
normally a computer. As an alternative to the mobile station
MS handling the control of a request for a USSD transaction,
the connected computer may handle the control in accordance
with a registered admission. The computer is equipped with
functions corresponding to those of the mobile station MS for
managing the control and registering the user admission.
Furthermore, the interface for connection between the mobile
station MS and the computer may be configured so that
relevant information contained in the request with respect to
a USSD transaction is transferred to the computer. The
decision as to whether the transaction may be carried out or
not is passed back from the computer to the mobile station
MS, which~then sends a reply to the request.
The inventive method described above with reference to Figure
2 includes a number of control checks that ascertain whether
the transaction requested is allowed or not. It will be
understood that not all of these controls need be carried out
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and that those controls which are to be carried out are
selected in the implementation of the control function.
Moreover, additional controls can be included in the method'.
One example of such additional controls resides in reading
the identity of the module in the mobile station MS that
shall receive a requested USSD transaction. The module is
given in the USSD component of the request and is designated
DCS (Data Coding Scheme). The user admission may, for
instance, be stated such as to stop a USSD transaction if its
data is intended for the display screen or loudspeaker of the
mobile station. One reason for stopping such transactions is
because the user becomes stressed when several types of data
are presented at one and the same time.
There are times when the USSD service node USSDgw sends over
an established USSD transaction request to send further
strings of information. The user admission may also state
that only a limited number of data transmission requests are
accepted within a transaction.
In the case of the aforedescribed embodiments, the control
has been carried out in response to a request for a USSD
transaction. It will be understood, however, that the
invention can be applied with other types of transactions
other than USSD transactions.
The described embodiments illustrate how the invention is
applied ~in a GSM network PLMN. It will be understood,
however, that the invention can also be applied in other
mobile communications systems. There is found in all mobile
communications systems a transaction-type circuit switched
data connection that is normally used for speech purposes.
The majority of mobile communications systems also include
types of transactions in which user data is transferred by a
transaction that is not circuit-switched connected. A
CA 02350461 2001-05-14
WO 00!30377 2 0 PCT/SE99/01882
transaction that is not circuit-switched is often transmitted
with the aid of protocol that is also used for signalling.
The USSD transaction and the SMS transaction are the names of
two such transactions in the GSM network PLMN. Similar types
of transactions have other names in other systems, although
they, unfortunately, lack a common designation.
Other mobile communications systems normally include a base
station instead of a radio base station BTS and a base
station switching centre BSC. The base station includes
essentially the same functions that are distributed in GSM
between the base station switching centre BSC and the radio
base transceiver station BTS. Functions which in the GSM
system are distributed on nodes in switching systems SS are
in other mobile communications systems distributed on nodes
that partly have other names but which together have
essentially the same functions as the switching systems SS of
the GSM system.
The invention is applicable for all mobile communications
systems where several transactions can be in progress in
parallel with one mobile station. By mobile communications
system is meant a cellular radio network in which the
mobility service is offered to mobile stations.
