CONTROL OF DATA FLOW TO A MOBILE STATION

Abstract: The present invention relates to a mobile station (MS), a method and a node (MS, HLR, MSC, VLR) in a mobile communications system (PLMN). The invention addresses the problem of the interference caused to a circuit-switched transaction by a non-circuit-switched transaction that is ongoing in parallel with the same mobile station (MS). It is normally a USSD transaction (USSD) that impairs the quality of a speech connection (TCH). The present invention provides a method which enables a user (A) of the mobile station to give in advance an upper data flow limit in the non-circuit-switched transaction. Control mechanisms in the mobile communications system then limit the data flow in accordance with said upper limit. The control is managed by an inventive mobile station or by the mobile switching centre (MSC). The advantage gained is that a smaller data flow results in less interference on the speech connection. Impairment of the speech connection can be rectified to a limited extend with the aid of coding.

Description: CONTROL OF DATA FLOW TO A MOBILE STATION 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 mode, and to a method pertaining to a mobile communications system and in particular when further transactions are setup with the mobile station parallel with a circuit switched data connection. DESCRIPTION OF THE BACKGROUND ART There are known to the art a number of solutions which enable mobile communications systems to setup 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 within a GSM network. Initially, it was only possible to setup one USSD transaction at a time with a 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 that is located outside the GSM network. Other service nodes can be connected to a USSD service node. These other service nodes allow the mobile station to access a number of applications through USSD transactions. The solution gives no limitation as to the number of USSD transactions that are setup with the mobile station. One Patent Application, SE 9803922-5, which has still not yet been published, addresses the problem whereby USSD transactions carried out in parallel with a circuit switched data connection impair the quality of the circuit switched connection. SE 9803922-5 provides a solution to the problem, by enabling the user of a mobile station to prevent in advance transactions being setup in parallel with an ongoing circuit switched data connection. SUMMARY OF THE INVENTION The present invention addresses a problem wherein a desired transaction to a mobile station which is ongoing parallel with a circuit switched data connection impairs the quality of said connection. It may be that transmission resources are taken from a circuit switched data connection and given to another transaction, wherewith the parallel ongoing transaction impairs the speech transmitted over a circuit switched data connection. Accordingly, an object of the present invention is to enable the user of a mobile station to limit in advance the data flow over one or more transactions that are ongoing in parallel with a circuit switched data connection, and therewith prevent interference on said circuit switched data connection. The aforesaid problem is solved by a method pertaining to a mobile communications system in which a user of a mobile terminal indicates in advance an upper limit for the data flow over one or more transactions that are ongoing in parallel with a circuit switched data connection. The data flow to the mobile terminal is determined and compared with said limit, and when this limit is exceeded a message is sent to the transmitter of said data flow informing said transmitter that no more data will be accepted. According to one aspect of the invention, the transaction is also aborted. According to another aspect, the transmitter of the data flow is informed of the delay time before further data can be sent to the mobile terminal. The aforesaid problem is also solved by a mobile terminal that has means for registering the upper limit for the amount of data that may be received per unit of time. The limit value is given by a mobile terminal user. The mobile station also includes means for measuring the data flow to the mobile terminal and comparing this data flow with the limit value, and means for informing the sender when the data flow exceeds said limit value. The aforesaid problem is also solved by a switching system that is connected to at least one base station system and therewith connected to a mobile terminal and also to a service node. The switching system also includes means for setting up a circuit switched data connection with the mobile terminal, and means for maintaining a circuit switched data connection with the mobile terminal and means for maintaining a parallel non-circuit-switched transaction between an external node and the mobile terminal. The switching system also includes means for registering a user indicated upper limit for data flow to the mobile station over the non- circuit-switched transaction. The switching system also includes means for measuring the flow of data to the mobile terminal and comparing this data flow with said limit value. The switching system also includes means for halting the data flow to the mobile terminal when this data flow would otherwise exceed said limit value. These solutions involve a number of different embodiments. According to one embodiment, the limit indicated by the user relates to data flow per unit of time. According to another embodiment, the limit pertains to the total data flow involved by the transaction. According to a further embodiment, the limit pertains to the data flow involved by respective applications to which said data flow refers. According to yet another embodiment, the limit pertains to a given receiving unit in the mobile terminal. In each of these embodiments, the data flow is determined and a comparison is made in accordance with the constraint to which said limit value relates. One advantage afforded by the present invention is that a user need not prevent a desired transaction because it disturbs an ongoing speech connection for instance. Instead, the user limits the data flow and therewith the interference that occurs on the speech connection. The user is thus able to receive the information in the data flow, although this will take somewhat longer. Speech over a circuit switched data connection is coded. When the speech interference lies beneath a given threshold value, the fault is rectified with the aid of the coding. On the other hand, when the interference lies above the threshold value, the coding is unable to correct the speech impairment and the speech quality will be very poor. With the aid of the present invention, a user is able to restrict the data flow so that the interference on the speech connection will lie within those levels that can be corrected by the coding. The invention will now be described in more detail with reference to preferred exemplifying embodiments thereof and also with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 illustrates a cellular mobile communications system and nodes included in the system. Figure 2 is a block schematic illustrating nodes included in the switching system (not complete). Figure 3 is a block schematic illustrating nodes that are active in transmitting a USSD request. Figure 4 is a flowchart describing an inventive method. DESCRIPTION OF PREFERRED EMBODIMENTS A number of embodiments of the present invention are described below with reference to a GSM network by way of example. Figure 1 illustrates 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 BTS1-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 Cl 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. A speech connection, i.e. a circuit switched data connection TCH, is setup between the mobile station MS and a telephone network terminal, via the gateway mobile switching centre GMSC. A USSD transaction USSD is also setup between the mobile station MS and the USSD service node USSDgw, via the gateway mobile switching centre GMSC. 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 setup through the GSM network for duplex connection TCH in this respect. The second type of transaction is an SMS transaction. An SMS transaction is a one-way connection, although it can be chosen either 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 an unstructured supplementary data service USSD. Similar to the SMS transaction, user data is transmitted transparently with signalling protocol within the GSM network PLMN. Distinct from 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 transactions in parallel. The standardising committee, ETSI, is in the process of standardising the way in which several USSD transactions can be setup simultaneously between the mobile station MS and one or more of the USSD service nodes USSDgw. Figure 1 illustrates a circuit switched transaction TCH and a USSD transaction USSD that are ongoing simultaneously with the mobile station MS. Figure 1 does not show the external telephone network to which the circuit switched data transaction is forwarded . A number of applications AP are connected to the USSD service node USSDgw. The applications AP may be either implemented in the USSD service node or in own service nodes that are connected to the USSD service node. The applications AP use the USSD service node for information transfer with the mobile station MS. The USSD transaction USSD uses a radio channel designated FACCH (Fast Associated Control CHannel) for the radio connection. The circuit switched data connection TCH uses a traffic channel TCH for the radio connection. The FACCH channel is setup only when data to be transmitted via this channel is found, and when setup will steal transmission capacity from the traffic channel. As a result, the quality of user data that has been transmitted on the traffic channel will be considerably impaired. Once speech is transmitted on the traffic channel, speech impairment or speech degradation can be corrected to a certain extent with the aid of coding. When speech impairment is greater than a given threshold value, the fault cannot be rectified by coding and the speech will become so poor that the receiver will be unable to understand what is said. Figure 2 shows the nodes of the switching system SS that are of significance with respect to the present invention. The switching system SS in Figure 2 thus includes the switching centre that, in turn, includes the home location register MSC/VLR, the gateway mobile switching centre GMSC and the home location register HLR. These nodes are connected to each other and to external nodes in accordance with what has been described above with reference to Figure 1. In order to simplify the description, it is assumed in the following that the USSD service node USSDgw connects directly to the home location register, as shown in Figure 3. Figure 3 illustrates how data is transferred from the USSD service node USSDgw to the mobile station MS in a USSD transaction that has already been established. Figure 3 also shows a further service node AS with application AP. As indicated by the arrow Al, data is sent from the further service node AS to the USSD service node USSDgw, and from there to the mobile station MS with the aid of USSD. The USSD service node divides the data from said further service node into USSD strings of mutually equal length. Each USSD string is packaged in a message USSD request which, in turn, is sent in a lower protocol storage message "TCAP-BEGIN" . This message is sent in accordance with the protocol MAP (Mobile Application Part). As shown by the arrow A2 in Figure 3, the USSD string is transferred from the USSD service node USSDgw to the home location register HLR and from there to the switching centre/visitor location register MSC/VLR, as shown by arrow A3. The USSD string is then sent to the mobile station MS, via the base station system BSS. When the USSD string arrives at the mobile station MS, said mobile station sends a response back to the USSD service node. The response informs the USSD service node whether the USSD string has been correctly received or has not been accepted. This latter case implies that the transaction is aborted and that, consequently, no further USSD strings can be transmitted. If the USSD string cannot be sent to the mobile station for some reason or another, the node that has not forwarded the USSD string, for instance the mobile switching centre MSC, sends a response back to the USSD service node USSDgw. Thus, the USSD service node expects to receive a response for each USSD string transmitted. The manner in which a USSD string is transmitted is known to the art and is described in more detail in the GSM 09.02 and GSM 03.90 specifications. The present invention enables the user A of the mobile station MS to limit data flow over a USSD transaction USSD that is ongoing in parallel with a circuit switched data connection TCH. Figure 4 is a flowchart which describes a method of limiting the data flow in a USSD transaction set up between the USSD service node USSDgw and the mobile station MS. The method includes a first step SI in which the upper data flow limit is given by the user A. The limit can be specified in a number of different ways, and consequently registration of said limit involves a number of different parameters. Among other things, the user A has the option of registering a block for USSD strings intended for a certain unit in the mobile station. Step 1 is followed by step S2, in which there is received a USSD request that includes a USSD string. In step S3 , a check is made to establish whether or not the data flow shall be controlled in accordance with a given limit. If the user A has registered that the data flow shall be limited, i.e. Yes to the question in step S3, step S4 is carried out. Otherwise, i.e. when the answer to the question is No, the USSD request message is accepted in accordance with step S8. In step S4, a check is made to ascertain whether or not a circuit switched data transaction is ongoing with the mobile station MS. If there is an ongoing transaction, i.e. the answer to the query is Yes, step S5 is carried out. On the other hand, if no circuit switched data transaction is connected, i.e. No to the query in step S4, the USSD request message is processed in a known manner. This means that the USSD request will probably be accepted. Alternatively, the controls described in SE 9803922-5 are carried out instead of processing the USSD request in said known manner. In step S5, it is ascertained whether or not the registered limit discloses that there is a unit within the mobile station to which USSD strings may not be sent, and in such case the identity of the unit. In a following step S6, the identity of a receiving unit in the mobile station MS may optionally be read from the USSD request message and compared with a possible identity read in step S6. When the two identities coincide, i.e. the answer to the query in S6 is Yes, the USSD string is intended for a non-permitted receiving unit within the mobile station, subsequent USSD strings are stopped in accordance with step S12. On the other hand, if the USSD string is accepted, i.e. the answer to the query in step S6 is No, step S7 is carried out. In step S7, a check, is made to ascertain whether or not the number of USSD request message that have been received over a given past period is less than an upper limit for the permitted number of USSD requests over a corresponding time period. If the answer is Yes, the data flow is below the maximum permitted limit value, the USSD request message is accepted and a response to this effect is sent back to the USSD service node in accordance with step S8. Step Sll is then carried out. If, on the other hand, the answer to the query in S7 is No, the USSD request will cause the data flow to be too large, step S9 is carried out. A parameter "Backpress" registered in step SI is read in step S9. If "Backpress" is activated, i.e. the answer to the query in step S9 is Yes, this means that the data flow shall be reduced, and hence step S10 is carried out. In step S10, a response to the USSD request message is sent back to the USSD service node USSDgw. The response includes a message to the effect that no further data can be accepted within a given time period. Step Sll is then carried out, wherein the time at which the USSD request message was received is saved in a buffer. The buffer is used in step S7 to count the number of USSD requests received over a latest time period, when a USSD request message is later received. On the other hand, if the answer to the query in step S9 is No, the flow shall not be retarded but stopped instead. A step S12 is then carried out, wherein a response "USSD- reject" is sent back to the USSD service node. The "USSD- reject" response also implies that the transaction between the USSD service node USSDgw and the mobile station MS is aborted. The method of dealing with a USSD request message is terminated after step S12 or after step Sll, but if a new USSD request is received, the method is restarted with step S2. The mobile station MS sends a response to a USSD request with a "Facility" message. A USSD request response having the significance used in steps S8 and S12 is previously known. The content of the response in step S10, on the other hand, is not previously known and shall be specified in order to enable it to be used. In addition to the controls described with reference to Figure 4 , further requirements are found with corresponding controls that the user A can setup in order to limit the data flow to the mobile station. For instance, the user A can allow only a limited number of USSD requests to a certain mobile station unit. Another example is that the user A may prohibit or allow only a given limited number of USSD requests that belong to a given application. Applications are given in a USSD request through a network element identifier NEI in combination with Port, which together give the address of the application AS. Another alternative is to only permit a certain total number of USSD requests per transaction, or per application. As an alternative to giving a later time at which data may be transmitted, the response sent to the USSD service node in step S10 may omit any reference to such time. In this case, the USSD service node must itself send a new USSD request at a later time. The response "USSD-reject" sent in accordance with step S12 is followed optionally by a later message sent to the USSD service diode to the effect that the mobile station is again prepared to receive USSD requests. This latter message is transmitted with a USSD message called "Process-USSD- request" . In the GSM network PLMN, the mobile station MS mobile switching centre MSC in combination with the visitor location register VLR, is commanded to register the upper data flow limit and to check that said data flow is in accord with the limit, as described with reference to the flowchart in Figure 4. As with earlier known mobile stations, an inventive mobile station MS that registers and checks data flow is equipped with a screen and keys with which the user A controls the mobile station MS. As with known mobile stations, the mobile station is also provided with a function for controlling more than one ongoing transaction USSD, TCH. The mobile station MS is also equipped with a register for storing those parameters that are included in the upper data flow limit. The mobile station MS includes means for sending a response to a received USSD request message. The mobile station MS is also provided with a function for controlling the status of the user A when a USSD request has been received, in accordance with the method described with reference to Figure 4. The user A of the mobile station MS initiates the data flow parameters, i.e. registers the conditions for data flow to the mobile station, with the aid of the mobile station keypad and instructions on the screen of the mobile station MS. The known control functions of the mobile station MS manage instructions from the user A and, in this case, control so that the admission parameters will be registered. The mobile station may include an application that facilitates initiation of the parameters in respect of the user A. According to GSM standards, a mobile station MS is comprised of the mobile equipment and a SIM card. The register containing admission parameters may either be included either in the mobile equipment or in the SIM card. The SIM card is provided by the GSM network operator, which has preset the admission parameters in a first state when these are stored in the SIM card. As an alternative to allowing the mobile station MS to deal with the registration and control of the user admission, this can be managed by the switching system SS. The switching system SS and its nodes are defined in GSM standards. The inventive switching centre/visitor location register MSC/VLR is equipped with a register for storing the admission of the user Ans . The switching centre/visitor location register MSC/VLR is also provided with a function for checking this admission when a request for the connection of a USSD transaction has been received, in accordance with the inventive method. If transmission of a USSD request is not in accord with the conditions setup by the user A, the mobile switching centre MSC prevents the USSD request from being forwarded to the mobile station MS. Instead, a response is sent back to the USSD service node USSDgw. This response either states that no further data may be sent within a given time period, in accordance with step S10, or that USSD requests will not be accepted, in accordance with step S9. The response is transported in a "TCAP Error" component. An earlier Patent Application SE 9803922-5 describes how a user A can limit the number of USSD transactions set up with the mobile station. The admission of user A can also be registered in this case and the control effected in accordance with this admission can be managed by either the mobile station or the mobile station switching centre MSC in combination with the visitor location register VLR. The controls described in SE 9803922-5 can be carried out conveniently in combination with the present invention. 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, which may be adapted to check the magnitude of the data flow instead of the mobile station MS performing this function. The computer is provided with functions corresponding to those of the mobile station MS for managing said checks, or controls, and registering the data flow limit. Furthermore, the interface for connection between the mobile station MS and the computer shall be configured to enable relevant information in USSD requests to be transferred to the computer. The decision as to whether the transaction may be carried out or not is sent from the computer back to the mobile station MS which then sends a reply to the request. In the aforedescribed embodiment, the check has been carried out upon receipt of a USSD request. The invention can also be applied to 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. 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 has 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 USSD service node USSDgw described in the above embodiments is an external node, which is the most likely scenario. However, the USSD service node may be integrated in the mobile communications system PLMN. The invention may also be applied with a node included in the mobile communications system PLMN as the sender of USSD requests. This node may, for instance, be the mobile switching centre MSC or the gateway mobile switching centre GMSC that generates USSD requests to the mobile station MS. The invention is valid with respect to all mobile communications systems where several transactions may be ongoing in parallel with a mobile station and can thus be applied also when none of two parallel transactions is a circuit-switched connection. By mobile communications systems is meant cellular radio networks in which services mobility are afforded to mobile stations.

Claims: CLAIMS 1. A method of limiting the data flow in at least one ongoing non-circuit-switched transaction to a given mobile terminal (MS) in a mobile communications system (PLMN) that includes a switching system (SS) connected to a service node (USSDgw), and at least one base station (BTS, BSC), wherein said mobile terminal (MS) is used by a given user (A), characterised by the steps of a) registering (SI) an upper data flow limit given to the mobile terminal by the user; b) setting up (S2) a circuit switched data connection with the mobile terminal; c) setting up at least one non-circuit-switched transaction to the mobile terminal; d) determining (Sll) said data flow to the mobile terminal (MS) over said transaction; e) comparing (S7) said data flow with said limit value; and f) preventing further data transmission in accordance with the result of said comparison (S10, S12). 2. A method according to Claim 1, wherein prevention (S10) of further data transmission is effected in the form of a message to said service node (USSDgw) informing said node that no further data may be sent to the mobile terminal within a given time period. 3. A method according to Claim 1, wherein prevention of said further data transmission (S12) is effected in the form of a message to the service node (USSDgw) informing said node that no further data will be accepted, wherewith said transaction is aborted. 4. A method according to Claim 3, wherein said message is later followed by a further message informing said node that further data can be accepted. 5. A method according to Claim 1, wherein said upper limit relates to data flow per unit of time, and wherein the data flow determining process and said comparison relate to data flow per unit of time. 6. A method according to Claim 1, wherein said upper limit relates to data flow per transaction, and wherein said data flow determining process and said comparison relate to data flow per transaction. 7. A method according to Claim 1, 4 or 6, wherein said upper limit also relates to a given application. 8. A method according to Claim 1, 4 or 6, wherein said upper limit also relates to a given receiver unit in the mobile terminal. 9. A method according to any one of the preceding Claims, wherein said non-circuit-switched transaction is a USSD transaction. 10. A method according to Claim 9, wherein measuring of the data flow according to step d) is effected by counting the number of USSD requests received by the mobile terminal. 11. A method according to Claim 1, 9 or 10, wherein said mobile communications system PLMN is the GSM system. 12. A mobile terminal (MS) used by a user (A) and comprising means for handling at least one non-circuit-switched transaction in parallel with a circuit switched connection via a radio connection in a mobile communications system (PLMN ) ; and - means which, when receiving data over the non-circuit- switched transaction, functions to send a response to the sender of said data, characterised by - means for registering an upper data flow limit given by the user (A) to the mobile terminal; - means for measuring the flow of data to the mobile terminal and comparing this data flow with said upper limit; and - means for informing the sender that no further data shall be sent to the mobile terminal, depending on the result of said comparison. 13. A mobile terminal (MS) according to Claim 12, in which said given admission is registered in the form of a list (L) of applications (AP) for which a transaction (TCH, USED, USED) may or may not be setup. 14. A mobile terminal (MS) according to Claim 12 or Claim 13, having means which function according to the specification for the GSM system. 15. A switching system (SS) which is connected to at least one service node (USSDgw), to at least one base station (BTS, BSC) and to at least one mobile terminal (MS) via said base station (BTS, BSC), and including - means for maintaining a circuit-switched data connection with said mobile terminal; - means for maintaining in parallel with the circuit-switched data connection a non-circuit-switched transaction over which data is transmitted from the service node (USSDgw) to said mobile terminal (MS), characterised by - means for registering an upper limit for data flow over said non-circuit-switched transaction, given by the user (A); - means for measuring the data flow to the mobile terminal; - means of comparing the measured data flow with said limit; and - means for preventing said data flow when it exceeds said limit.

Inventors: EDLUND PETER HANS, EDLUND, PETER, HANS
Applicants: ERICSSON TELEFON AB L M, TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)
Application year: 1999
Main classification: H04Q7
IPC codes: H04L12, H04W28