Abstract:
In providing a wireless communication service of a selected type, a user of a mobile communication device may attempt to access the selected type of service despite his/her subscription to a different type of service. In processing the device&#39;s request for accessing the selected type of service, an authentication vector is retrieved based on information identifying the device in the request. The access to the selected type of service may be denied after it is determined that a presentation of the authentication vector does not conform to the selected type of service.

Description:
FIELD OF THE INVENTION  
       [0001]    The invention relates to a technique for providing a wireless communication service and, more particularly, to a technique for controlling access to a wireless communication service. 
       BACKGROUND OF THE INVENTION  
       [0002]    This section introduces aspects that may help facilitate a better understanding of the invention. Accordingly, the statements of this section are to be read in this light and are not to be understood as admissions about what is prior art or what is not prior art. 
         [0003]    Wireless communication services provisioned according to the global system for mobile communications (GSM) and universal mobile telecommunication system (UMTS) standards are common nowadays. UMTSs are so-called “third generation (3G)” mobile communication systems, which gradually are supplanting “second generation (2G)” systems, e.g., GSM systems, used in many wireless service areas. During this migration from 2G mobile communication technology to 3G technology, many wireless service providers provide both the GSM and UMTS services in the same service area. 
         [0004]    A UMTS service generally is a premium service relative to a GSM service. The UMTS service usually affords voice and data communications of a higher quality and capacity than the GSM service. The UMTS service also can provide video telephony (e.g., video conferencing) and high CD quality sound on a 3G mobile communication device. In addition, it can provide better location information and thus more sophisticated location-based services than the GSM service. 
         [0005]    Other differences between the UMTS service and GSM service include their service security. The GSM service security involves a well known unilateral authentication process where one or more GSM authentication vectors are used to authenticate a mobile communication device towards a GSM network. On the other hand, the UMTS service security involves a well known bilateral authentication process where one or more authentication vectors are used not only to authenticate a mobile communication device towards a UMTS network, but also the UMTS network towards the device. 
       BRIEF SUMMARY  
       [0006]    The invention is directed to a technique for restricting a user, e.g., from accessing a selected type of wireless communication service who has subscribed to a different type of service. For example, as mentioned before a UMTS service generally is a premium service relative to a GSM service. However, GSM subscribers may be able to access the UMTS service without purchasing the premium UMTS subscription by inserting their GSM subscriber identity module (SIM) card (signifying their GSM service subscription) in a UMTS mobile device. Such GSM subscribers may be restricted from accessing the UMTS service, in accordance with an aspect of the invention. Conversely, UMTS subscribers may be restricted from accessing the GSM service to not overburden a limited GSM capacity, in accordance with another aspect of the invention. 
         [0007]    In implementing the invention, when a request from a mobile device for accessing a wireless communication service (e.g., a location update request) is received via a communication facility, which is provisioned in accordance with a selected type of wireless communication service, authentication data (e.g., the aforementioned authentication vector) associated with the mobile device is obtained. In accordance with the invention, one or more restrictions may be imposed on the mobile device after it is determined that a presentation of the authentication data does not conform to the selected type of wireless communication service, for example, its data format, number of parameters in an authentication vector, and/or bit lengths of the individual parameters, etc. not meeting the specification of the selected type of service. One such restriction illustratively imposed on the mobile device may be denying its access to the wireless communication service. Another restriction may be a roaming restriction pre-agreed upon between an operator of a home public land mobile network (PLMN) to which a subscriber belongs and that of a visitor PLMN to which his/her mobile device roams. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0008]      FIG. 1  is a block diagram of a mobile communication system according to an illustrative embodiment of the invention; 
           [0009]      FIG. 2  is a flow chart depicting an authentication process according to the GSM standard which is used in the system of  FIG. 1 ; 
           [0010]      FIG. 3  is a flow chart depicting an authentication process according to the UMTS standard which is used in the system of  FIG. 1 ; 
           [0011]      FIG. 4  is a flow chart depicting a process for restricting access to a UMTS service provided by the system of  FIG. 1 ; 
           [0012]      FIG. 5  is a block diagram of a mobile communication system according to a second illustrative embodiment of the invention; and 
           [0013]      FIG. 6  is a flow chart depicting a process for restricting access to a GSM service provided by the system of  FIG. 5 . 
       
    
    
     DETAILED DESCRIPTION  
       [0014]      FIG. 1  illustrates wireless communication system  100  embodying the principles of the invention, and a representative mobile communication device, denoted  103 . Device  103  may be a mobile phone, smart phone, iPhone®, personal digital assistant (PDA), Blackberry®-type device, Kindle™-type device, notebook or netbook computer, pocket personal computer (PPC), hand-held or portable device, etc. which is capable of wireless communications, and which may be incorporated in a system in a vehicle or mobile environment, e.g., in a car, airplane, etc. A subscriber may use device  103  to access a wireless communication service provided by system  100  through radio access network (RAN) subsystem  105 . System  100  in this instance provides two types of wireless communication service, which may be, e.g., GSM and UMTS services. However, in accordance with the invention, a subscriber using device  103  may be denied the UMTS service provided by system  100  if it is determined that the subscriber has subscribed only to the GSM service. Conversely, a subscriber using device  103  may be denied the GSM service provided by system  100  if it is determined that the subscriber has subscribed only to the UMTS service. The actual service subscription may be identified by the type of a subscriber identity module (SIM) card  104 , which needs to be inserted in device  103  when used. As is well known, a GSM SIM card comprises a portable memory chip which contains hard-coded personal GSM subscription and authentication information. As is also well known, a UMTS SIM (USIM) is realized as an application run on a UMTS IC card (UICC), a smart card. The USIM contains functions and data needed to identify and authenticate the associated mobile communication device to the UMTS service. 
         [0015]    Core network subsystem  107  administers the mobile communication services and is capable of establishing and maintaining a communication, e.g., by device  103  through external network  109 , e.g., a public switched telephone network (PSTN), internet protocol (IP) network, microwave network, satellite network, cable network, optical fiber network, etc., or a combination thereof. 
         [0016]    In this illustrative embodiment, RAN subsystem  105  includes wireless facilities and channels for a GSM/EDGE radio access network (GERAN) and UMTS terrestrial radio access network (UTRAN), thereby supporting radio accesses to both the GSM and UMTS services. The GERAN part of subsystem  105 , denoted  111 , illustratively includes base station controller (BSC)  113  which, among other things, controls operations of base stations  117  and  119  in a well known manner to carry out the GSM service. Each of base stations  117  and  119  establishes physical radio connections, e.g., with device  103  accessing a wireless communication service. The UTRAN part of subsystem  105 , denoted  121 , illustratively includes radio network controller (RNC)  123  which, among others things, controls operations of base stations  117  and  119  in a well known manner to carry out the UMTS service. Base stations  117  and  119  may also be known as nodes B according to the UMTS standard. 
         [0017]    Core network subsystem  107  illustratively includes mobile switching center (MSC)  131 , home location register/authentication center (HLR/AuC)  133  and visited location register (VLR)  135 . Processing unit  142  in MSC  131  is responsible for, among other things, originating and terminating a circuit switched connection between a mobile communications device (e.g., device  103 ) and another device via external network  109 . For example, processing unit  142  performs switching and signaling functions through switching fabrics  144  to establish communication connections for subscribers in the service area associated with MSC  131 . In this instance, it also controls radio resources for the UMTS service in accordance with RNC profile  146 , and for the GSM service in accordance with a BSC profile  148 . Both profiles  146  and  148  are stored and maintained in memory  149 . Also installed in memory  149  may be service access restriction software (described below) for restricting a subscriber from using a service to which he/she is not subscribed, in accordance with some embodiments of the invention. 
         [0018]    HLR/AuC  133  includes a conventional HLR and AuC which are associated with each other and in this instance are implemented in the same physical node. The HLR comprises a database for management of subscribers to the instant UMTS/GSM services. As is well known, the HLR contains international mobile subscriber identities (IMSIs) of the service subscribers which are used as keys to access other information about the subscribers and their subscription. Such other information includes billing information, information concerning subscribed service features, roaming limitations, authentication information, etc. Together with VLR  135 , the HLR also handles mobility management. For example, to route and charge calls, the HLR maintains information concerning the VLR with which a subscriber currently in the location area (LA) associated with the VLR is registered. The AuC contains data needed for authentication and ciphering to maintain service integrity for each subscriber. VLR  135  contains a copy of data from the HLR and other data for properly providing a wireless communication service to each subscriber currently visiting the LA associated with VLR  135 . Specifically, VLR  135  contains the subscriber&#39;s mobile device identity and authentication-related data, last known LA of the device, power class and other physical attributes of the device, a list of special services available to the subscriber, etc. 
         [0019]    It should be noted at this point that various embodiments involve use of a certain authentication vector or parameters, occasioned by an authentication process in providing the instant GSM/UMTS service, to determine the actual service (GSM or UMTS service) subscribed by a subscriber. For example, when a mobile communication device (e.g., device  103 ) is turned on in the LA associated with VLR  135 , the device needs to register with system  100 . The authentication process involving the device may be initiated during one such registration. To better appreciate these embodiments, a conventional GSM authentication process and UMTS authentication process will now be described, with the aid of  FIGS. 2 and 3 , respectively. 
         [0020]    Referring to  FIG. 2 , processing unit  142  in MSC  131  may perform the conventional GSM authentication process when device  103  registers with the GSM service part of system  100 . Based on the information identifying device  103  during the registration, processing unit  142  at step  205  requests from HLR/AuC  133  multiple distinct authentication vectors (RAND, SRES, Kc) associated with device  103 , where RAND represents a random challenge which is a 128-bit random number generated in the AuC; SRES represents a 32-bit signed result from using a secret key Ki signing the RAND; and Kc represents a 64-bit ciphering key used as a session key to initiate an encryption algorithm (conventionally known as A5) for encrypting the over-the-air radio communications between device  203  and a base station. The secret key Ki is shared between device  103  and HLR/AuC  133 . Specifically, a copy of Ki is stored in SIM card  104  (a GSM SIM card in this instance), and the other copy in the AuC. The ciphering algorithm for signing the RAND with the secret key Ki to generate SRES is conventionally known as A3. Thus, in short SRES=A3(RAND, Ki). The session key Kc is computed by the AuC applying a ciphering algorithm (conventionally known as A8) to the RAND and secret key Ki, i.e., Kc=A8(RAND, Ki). Because of the fact that a GSM authentication vector contains three parameters, i.e., RAND, SRES and Kc, it is oftentimes referred to as an “authentication triplet.” 
         [0021]    At step  208 , processing unit  142  receives the requested authentication triplets, and stores them in VLR  135 . At step  212 , processing unit  142  selects one of the received authentication triplets to authenticate mobile communication device  103 . At step  216 , processing unit  142  sends an authentication request, including the RAND parameter in the selected triplet, to device  103 . 
         [0022]    Once device  103  receives the RAND from processing unit  142 , device  103  computes SRES′=A3(RAND, Ki), where the shared secret key Ki is from SIM card  104 . Device  103  sends its computed SRES′ to MSC  131 . 
         [0023]    Upon receiving the SRES′ in MSC  131 , processing unit  142  at step  218  determines whether the received SRES′ is identical to the SRES from the previously selected authentication triplet. If they are identical, device  103  is deemed to be authenticated, as indicated at step  220 . Otherwise, the authentication fails, as indicated at step  224 . 
         [0024]    Referring to  FIG. 3 , processing unit  142  in MSC  131  may perform the conventional UMTS authentication process when device  103  registers with the UMTS service part of system  100 . Based on the information identifying device  103  during the registration, processing unit  142  at step  305  requests from HLR/AuC  133  multiple distinct authentication vectors (RAND, XRES, AUTN, CK, IK) associated with device  103 , where RAND represents a random challenge which is a random number generated in the AuC; XRES represents an expected response by a USIM in device  103  to the random challenge; AUTN represents an authentication token that authenticates the AuC towards the USIM; CK represents a cipher key for confidentiality; and IK represents an integrity key for integrity checking. Because of the fact that a UMTS authentication vector contains five parameters, i.e., RAND, XRES, AUTN, CK and IK, it is oftentimes referred to as an “authentication quintuplet.” 
         [0025]    It should be noted at this point that the AuC stores a secret key K, shared between device  103  and the HLR/AuC  133 . Specifically, a copy of the secret key K is stored in SIM card  104  (a UICC in this instance), and the other copy in the AuC. In addition, the AuC stores such well known message authentication and key generating functions, f 0 -f 5 , according to the UMTS standard. In fact, some of the above authentication parameters may be expressed using these functions, namely, XRES=f 2 (K, RAND), CK=f 3 (RAND), and IK=f 4 (RAND). 
         [0026]    At step  308 , processing unit  142  receives the requested authentication quintuplets, and stores them in VLR  135 . At step  312 , processing unit  142  selects one of the received authentication quintuplets. At step  316 , processing unit  142  sends an authentication request, including the RAND and AUTN parameters in the selected quintuplet, to mobile communication device  103 . 
         [0027]    Once device  103  receives the RAND from processing unit  142 , in a well known manner the USIM in device  103  verifies the received AUTN to authenticate system  100 , and computes a response RES=f 2 (K, RAND) based on the shared secret key K in SIM card  104  and the received RAND. Device  103  sends its computed RES to MSC  131 . 
         [0028]    Upon receiving the RES in MSC  131 , processing unit  142  at step  318  determines whether the received RES is identical to the XRES from the previously selected authentication quintuplet. If they are identical, device  103  is deemed to be authenticated, as indicated at step  320 . Otherwise, the authentication fails, as indicated at step  324 . 
         [0029]    After the UMTS authentication, MSC  131  sends the parameters CK and IK in the previously selected authentication quintuplet to RNC  123  for ciphering and integrity checking of communications by device  103 . 
         [0030]    In general, a UMTS service is a premium service relative to a GSM service because the UMTS service can afford better voice and data communications than the GSM service, and video communications (e.g., video conferencing) which the GSM service lacks. Some embodiments are premised upon the recognition that GSM subscribers may be able to access a UMTS service without purchasing the premium UMTS subscription by inserting their GSM SIM card (signifying their GSM service subscription) in UMTS equipment. In accordance with one such embodiment, such GSM subscribers (with GSM SIM cards) are restricted from accessing the UMTS service part of system  100 . To that end, RNC profile  146  in MSC  131  is provisioned with an option of “GSM SIM restricted from UTRAN access” (“GSM SIM restriction” in short) which is selected in this illustrative embodiment. 
         [0031]    To demonstrate this embodiment, let&#39;s assume that mobile communication device  103  is UMTS equipment in which a GSM subscriber has inserted a GSM SIM card as card  104 . When device  103  roams to an LA serviced by system  100  from another LA outside system  100 , device  103  attempts to register onto MSC  131  via UTRAN  121 . Accordingly, processing unit  142  in MSC  131  receives from mobile communication device  103 , via UTRAN  121  and interface  151  in MSC  131 , a location update request including information identifying device  103 , as indicated at step  405  in  FIG. 4 . Processing unit  142  at step  407  determines that the GSM SIM restriction in RNC profile  146  is imposed in this instance. Knowing that the location update request came from RNC  123  in UTRAN  121 , processing unit  142  at step  412  requests from HLR/AuC  133  authentication vectors associated with device  103  based on the received device identifying information. After receiving at least one authentication vector from HLR/AuC, processing unit  142  at step  415  determines that in this instance the received authentication vector associated with device  103  is not a UMTS authentication quintuplet. Rather, the received authentication vector actually is a GSM authentication triplet because of the subscriber&#39;s GSM subscription. Processing unit  142  can identify a UMTS authentication quintuplet by its data presentation including, but not limited to, its data format, the number of individual parameters (i.e., five) therein, and/or bit lengths of the individual parameters, pursuant to the UMTS standard. In accordance with this embodiment, processing unit  142  at step  418  transmits a location update reject to device  103  in response to its outstanding location update request. When the location update request by device  103  is rejected due to the GSM restriction, the cause of the rejection given to device  103  may be unavailability of suitable cells in the new LA. Accordingly, device  103  marks the new LA as unusable. However, this cause of rejection is for illustrative purposes only. It will be appreciated that those skilled in the art may provision RNC profile  146  with other causes of rejection to meet their particular application needs. It should also be noted that software instructions for the routine described in  FIG. 4  may be stored in memory  149  of  FIG. 1 . 
         [0032]    In a second embodiment of the invention, let&#39;s assume wireless communication system  100  only provides the GSM service, thus without the UMTS service.  FIG. 5  illustrates such a version of system  100  in this second embodiment which is denoted  500 . Like system  100 , wireless communication system  500  in this instance provides access to the GSM service via GERAN  111 , and includes core network subsystem  107  and external network  109  described before. However, unlike system  100 , system  500  does not include any UTRAN provisions and, in particular, RNC profile  146  is no longer provisioned in subsystem  107  of system  500 . Let&#39;s also assume that in this second embodiment that mobile communication device  503  in  FIG. 5  is dual mode equipment, operating pursuant to both the GSM and UMTS standards, in which a UMTS subscriber has inserted UICC  504  on which a USIM runs. In addition, in this instance BSC profile  148  in MSC  131  of subsystem  107  is provisioned with an option of “USIM restricted from GERAN access” (“USIM restriction” in short) which is selected. This restriction may be imposed to prohibit a UMTS subscriber from utilizing an inferior GSM service, given the fact that the subscriber has paid for a premium UMTS service subscription. Other reasons for the restriction may be that system  500  currently is serving GSM subscribers at its full capacity and cannot be overburdened by serving additional UMTS subscribers. 
         [0033]    When device  503  roams to an LA serviced by system  500  from another LA outside system  500 , device  503  attempts to register onto MSC  131  in subsystem  107  via GERAN  111 . Accordingly, processing unit  142  in MSC  131  receives from device  503 , via GERAN  111  and interface  151  in MSC  131 , a location update request including information identifying device  503 , as indicated at step  605  in  FIG. 6 . Processing unit  142  at step  613  determines that the USIM restriction in BSC profile  148  is imposed in this instance. Knowing that the location update request came from BSC  113  in GERAN  111 , processing unit  142  at step  615  requests from HLR/AuC  133  authentication vectors associated with device  503  based on the received device identifying information. After receiving at least one authentication vector from HLR/AuC  133 , processing unit  142  at step  618  determines that in this instance the received authentication vector associated with device  503  is not a GSM authentication triplet. Rather, the received authentication vector actually is a UMTS authentication quintuplet because of the subscriber&#39;s UMTS subscription. Processing unit  142  can identify a GSM authentication triplet by its presentation including, but not limited to, its data format, the number of individual parameters (i.e., three) therein, and/or bit lengths of the individual parameters, pursuant to the GSM standard. In accordance with this embodiment, processing unit  142  at step  622  transmits a location update reject to device  503  in response to its outstanding location update request. When the location update request by device  503  is rejected due to the USIM restriction, the cause of the rejection given to device  503  may be unavailability of suitable cells in the new LA. Accordingly, device  503  marks the new LA as unusable. Again, this cause of rejection is for illustrative purposes only. It will be appreciated that those skilled in the art may provision BSC profile  148  with other causes of rejection to meet their particular application needs. It should also be noted that software instructions for the routine described in  FIG. 6  may be stored in memory  149  of subsystem  107 . 
         [0034]    The foregoing merely illustrates the principles of the invention. It will thus be appreciated that those skilled in the art will be able to devise numerous arrangements which embody the principles of the invention and are thus within its spirit and scope. 
         [0035]    For example, in system  100  where both UMTS and GSM services are provided, even though only the GSM SIM restriction is imposed in the illustrative embodiment, it will be appreciated that the above-described USIM restriction may also be imposed if so desired. 
         [0036]    In addition, in the embodiments of the invention, the GSM SIM and USIM restrictions are provisioned in an MSC (e.g.,  131 ) for administering circuit switched connections. However, the invention is applicable not only in a circuit switched environment, but also a packet switched environment or other voice/data/video transport environments. For example, for the data service, the GSM SIM and USIM restrictions in accordance with the invention may be provisioned on a well known serving general packet radio service (GPRS) support node (SGSN), analogous to the MSC. 
         [0037]    Moreover, in another embodiment of the invention, an MSC or SGSN can selectively enforce the above-described access restrictions and/or other restrictions based on the IMSI of a subscriber, which contains an identification of the home public land mobile network (PLMN) to which the subscriber belongs. In that embodiment, when the subscriber&#39;s mobile communication device roams to a visitor PLMN, and the MSC or SGSN of the visitor PLMN determines an authentication vector discrepancy, e.g., from step  415  of  FIG. 4  or step  618  of  FIG. 6 , the MSC or SGSN may further check the IMSI in the SIM of the roaming device for the identification of its home PLMN. Depending on a prior agreement between operators of the home PLMN and visitor PLMN, the MSC or SGSN may selectively impose upon the roaming device an access restriction described above and/or other roaming restrictions. 
         [0038]    Further, although in the disclosed embodiments a mobile communication device (e.g.,  103 ) accesses a wireless communication service (e.g., UMTS, GSM, etc.) through an RNC or BSC via a radio access network (RAN), it will be appreciated that the device may access the same wireless communication service via a wired connection (e.g., web connection) to the RNC or BSC. For example, it is envisioned that in one such web connection arrangement, a mobile communication device may be wirelessly connected to the web, e.g., via Wi-Fi or other wireless LAN in a home, cafe, airport, Wi-Fi “hot zone,” etc. 
         [0039]    Finally, although wireless communication systems  100  and  500  are embodied in the form of various discrete functional blocks, these systems could equally well be embodied in an arrangement in which the functions of any one or more of those blocks or indeed, all of the functions thereof, are realized, for example, by one or more appropriately programmed processors or devices.