Patent Publication Number: US-2019191303-A1

Title: Deployable Cell And Method For Validating A Deployable Cell To Be Fully Operational

Description:
BACKGROUND OF THE INVENTION 
     Portable communication systems, such as vehicular ad hoc networks, are effective in providing mobile cellular and private mobile network services. As these systems are portable, they are vulnerable to theft or unauthorized physical access. This could lead to the eventual risk of compromising security keys stored in memory of the portable communication systems. In current solutions, all SIM cards need to be replaced in all mobile devices that can use the portable communication system in order to overcome the potential compromising of the secret keys on each of the mobile device&#39;s SIM cards. 
     A further problem with a stolen or compromised portable communication system is that unauthorized use of such a system could interfere with other deployed systems. 
     An additional problem with a stolen portable communication system is that, without some mechanism to stop operation, the system can be used by the thieving parties. Stolen deployable communication systems should somehow be disabled so that they are not operational if stolen. 
     Therefore, a need exists for a method of securing a deployable cell so that it is fully operational when desired while not operational when stolen. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
       The accompanying figures, where like reference numerals refer to identical or functionally similar elements throughout the separate views, which together with the detailed description below are incorporated in and form part of the specification and serve to further illustrate various embodiments of concepts that include the claimed invention, and to explain various principles and advantages of those embodiments. 
         FIG. 1  depicts a system diagram of a portion of a communication system in accordance with an exemplary embodiment of the present invention. 
         FIG. 2  depicts a flow chart in accordance with an exemplary embodiment of the present invention. 
         FIG. 3  depicts a call flow diagram in accordance with an exemplary embodiment of the present invention. 
     
    
    
     Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the present invention. 
     The apparatus and method components have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein. 
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  depicts a system diagram of a portion  100  of a communication system in accordance with an exemplary embodiment of the present invention. In accordance with an exemplary embodiment, portion  100  of the communication system includes network  101 , supervisor  103 , deployable cell  105 , and regular subscribers  111 ,  112 , and  113 . It should be understood that there can be a plurality of deployable cells, subscribers, and supervisors in portion  100 , but only the above elements are shown for purposes of clarity. 
     Network  101  is a cellular or mobile network and also preferably includes links to the public switched telephone network (PSTN). Network  101  provides for communication between users on the same or different networks. 
     Deployable cell  105  is a mobile, cellular base station that allows subscribers, such as public safety personnel, to connect to and utilize a cellular and telephone network. Deployable cell  105  preferably provides access to voice data, video, text, and other communication services. 
     In accordance with an exemplary embodiment, deployable cell  105  includes two modes of operation for subscribers. A first mode of operation is full operational mode, and a second mode of operation is restricted network node. In full operational mode, full network service is provided for subscribers to the network. For example, if the network is an LTE network, in full operational mode maximum LTE coverage is provided. 
     In an exemplary embodiment, restricted network mode is the mode of operation upon powering on deployable cell  105 . In restricted network mode the coverage area is restricted, preferably to tens of meters. This can be accomplished using low RF transmission power or other low power techniques, such as, Wi-Fi or Bluetooth. In restricted network mode, limited network services are provided, preferably only authentication of supervisors. 
     Supervisor  103  is a mobile device, such as a cell phone, a land mobile radio, or any other portable mobile device that can communicate with deployable cell  105 . In accordance with an exemplary embodiment, supervisor  103  is a subscriber that is equipped to enable deployable cell  105  to switch from restricted network mode to full operational mode. In accordance with an exemplary embodiment, there are a limited number of supervisors within communication system  100 . 
     Subscribers  111 ,  112 , and  113  are mobile devices, such as cell phones, land mobile radios, or any other portable mobile device that can communicate with deployable cell  105 . In accordance with an exemplary embodiment, subscribers  111 ,  112 , and  113  are able to receive and utilize network services via deployable cell  105 , but are not able to approve deployable cell  105  to operate in full operational mode. 
     In the exemplary embodiment depicted in  FIG. 1 , mobile device  103  is depicted as a supervisor and mobile devices  111 ,  112 , and  113  are depicted as regular subscribers. Deployable cell  105  preferably identifies mobile device  103  as a supervisor by checking a database in deployable cell  105  where supervisor IMSIs are stored. Deployable cell  105  preferably identifies mobile devices  111 ,  112 , and  113  as subscribers by checking the IMSI database in deployable cell  105  and recognizing that mobile devices  111 ,  112 , and  113  are not indicated in the supervisor group. 
       FIG. 2  depicts a flow chart  200  in accordance with an exemplary embodiment of the present invention. 
     Deployable cell  105  powers on ( 201 ). In accordance with an exemplary embodiment, deployable cell  105  is provided power upon arriving at an incident scene. 
     Upon powering on, deployable cell  105  enters ( 203 ) a restricted mode. Restricted mode provides limited network services, for example authentication by a supervisor such as mobile device  103 . In accordance with an exemplary embodiment, the transmission power of deployable cell  203  is lowered when in restricted mode. By powering up in restricted mode, only supervisor mobile units can authorize deployable cell  105  to operate in full operational mode. This feature prevents a stolen deployable base station from becoming useful unless the thieves have access to a supervisor mobile device. Without a supervisor mobile device, the stolen deployable cell is limited to very short range communications and rejects any subscribers from attaching to the stolen deployable cell or accessing any wireless services. 
     At some point, deployable cell  105  receives ( 205 ) an attach request from a mobile device. The attach request is preferably received from a nearby mobile device, since deployable cell  105  is in restricted mode and therefore is limited to short range communications. 
     Deployable cell  105  determines ( 207 ) if the attach request is from a supervisor. In an exemplary embodiment, deployable cell  105  accomplishes this by checking if a subscriber ID, such as the IMSI, of the sending mobile device is located in a supervisor database located within deployable cell  105 . If the subscriber ID is in the supervisor database, the sending mobile unit is considered to be a supervisor. 
     If the request is not from a supervisor, deployable cell  105  rejects ( 217 ) the attach request. The process then returns to step  203  and remains in restricted mode. 
     If the attach request is from a supervisor as determined at step  207 , deployable cell  105  determines ( 209 ) if authentication of the mobile device is successful. If the authentication is not successful, the process returns to step  203  and remains in restricted mode. 
     The supervisor mobile device is checked at this step to not only ensure that the supervisor bit is checked, but that it has the proper keys to be an actual supervisor. In accordance with an exemplary embodiment, supervisor mobile devices are authenticated using a combination of two factors, key-based authentication and close proximity to deployable cell  105 . 
     The key-based authentication is preferably a shared secret authentication scheme. In this type of authentication, a part of the key is stored in the network and a second part of the key is stored in supervisor mobile devices. In this manner, by splitting the keys of subscriber mobile devices between the system and supervising mobile devices, in the absence of a supervisor mobile device, subscriber mobile devices cannot attach to the system as the system does not have a full key to validate the subscriber mobile devices. A challenging method is used where hashes of the keys are compared. 
     If the authentication was successful as determined at step  209 , deployable cell  105  enters ( 211 ) full operational mode. In full operational mode, subscribers  111 ,  112 , and  113  are able to attach to deployable cell  105  and utilize the network for communications. In addition, the transmission power of deployable cell  105  is preferably increased when in full operational mode. 
     At some point, deployable cell  105  receives ( 213 ) a detach request from supervisor mobile device  103 . This typically happens when mobile device  103  moves out of range of deployable cell  105 . 
     In this exemplary embodiment, since supervisor  103  was providing authentication of deployable cell  105 , deployable cell  105  determines ( 219 ) if a supervisor is still attached to deployable cell  105 . If there are no supervisors attached to deployable cell  105 , deployable cell  105  returns to step  203  and once again enters restricted mode. In this mode, communication resources are not available to subscriber mobile devices  111 ,  112 , ad  113 . 
     If it is determined at step  219  that there is still a supervisor attached to deployable cell  105 , deployable cell  105  returns to step  211  and continues operating in full operational mode. 
       FIG. 3  depicts a call flow diagram  300  in accordance with an exemplary embodiment of the present invention.  FIG. 3  depicts the call flow for a subscriber unit, such as any of the subscriber units  111 ,  112 , or  113 , attempting to connect to deployable cell  105 .  FIG. 3  depicts subscriber unit  111  attempting to attach to deployment cell  105 . 
     In accordance with an exemplary embodiment, subscriber  111  sends Attach Request  301  to deployable cell  105 . Attach Request  301  is a request to connect to deployable cell  05  in order to utilize the services of deployable cell  105  and communication system  100 . 
     Upon receiving Attach Request  301  from subscriber  111 , deployable cell  105  will request the shared secret part from the attached supervisor  103 . In order to verify that subscriber  111  should be able to use communication system  100 , deployable cell  105  sends Request Key Part message  303  to supervisor  103 . Request Key Part message  303  includes a request for a part of the shared secret key (Ki) stored on supervisor  103 . 
     After verifying that it should send its part of the key, supervisor  103  sends Response Key Part message  305  to deployable cell  105 . Response Key Part message  305  includes the part of the Ki stored on Supervisor  103 . 
     Deployable cell  105  cryptographically combines ( 307 ) the part of the Ki received in Response Key Part message  305  with a part of the Ki provisioned in a Home Subscriber Server (HSS) to form a shared secret key. In accordance with an exemplary embodiment, only combining both parts together cryptographically results in the same shared secret key provisioned in the SIM card of subscriber  111 . 
     Deployable cell  105  sends Authentication Response message  309  to subscriber  111 . Authentication Response message  309  is a request to subscriber  111  to provide a hash of a secret key stored on subscriber  111 . 
     Subscriber  111  sends Authentication Response message  311  to deployable cell  105 . Authentication Response message  311  preferably includes a hash of the secret key stored on subscriber  111 . 
     Deployable cell  105  authenticates ( 313 ) the keys in any acceptable manner. For example, a challenge method can be used to compare hashes of the two keys. If the keys do not authenticate, subscriber  111  is denied access to deployable cell  105 . 
     In the foregoing specification, specific embodiments have been described. However, one of ordinary skill in the art appreciates that various modifications and changes can be made without departing from the scope of the invention as set forth in the claims below. Accordingly, the specification and figures are to be regarded in an illustrative rather than a restrictive sense, and all such modifications are intended to be included within the scope of present teachings. The benefits, advantages, solutions to problems, and any element(s) that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as a critical, required, or essential features or elements of any or all the claims. The invention is defined solely by the appended claims including any amendments made during the pendency of this application and all equivalents of those claims as issued. 
     Moreover in this document, relational terms such as first and second, top and bottom, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. The terms “comprises,” “comprising,” “has”, “having,” “includes”, “including,” “contains”, “containing” or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises, has, includes, contains a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. An element proceeded by “comprises . . . a”, “has . . . a”, “includes . . . a”, “contains . . . a” does not, without more constraints, preclude the existence of additional identical elements in the process, method, article, or apparatus that comprises, has, includes, contains the element. The terms “a” and “an” are defined as one or more unless explicitly stated otherwise herein. The terms “substantially”, “essentially”, “approximately”, “about” or any other version thereof, are defined as being close to as understood by one of ordinary skill in the art, and in one non-limiting embodiment the term is defined to be within 10%, in another embodiment within 5%, in another embodiment within 1% and in another embodiment within 0.5%. The term “coupled” as used herein is defined as connected, although not necessarily directly and not necessarily mechanically. A device or structure that is “configured” in a certain way is configured in at least that way, but may also be configured in ways that are not listed. 
     It will be appreciated that some embodiments may be comprised of one or more generic or specialized electronic processors (or “processing devices”) such as microprocessors, digital signal processors, customized processors and field programmable gate arrays (FPGAs) and unique stored program instructions (including both software and firmware) that control the one or more processors to implement, in conjunction with certain non-processor circuits, some, most, or all of the functions of the method and/or apparatus described herein. Alternatively, some or all functions could be implemented by a state machine that has no stored program instructions, or in one or more application specific integrated circuits (ASICs), in which each function or some combinations of certain of the functions are implemented as custom logic. Of course, a combination of the two approaches could be used. 
     Moreover, an embodiment can be implemented as a computer-readable storage medium having computer readable code stored thereon for programming a computer (e.g., comprising an electronic processor) to perform a method as described and claimed herein. Examples of such computer-readable storage mediums include, but are not limited to, a hard disk, a CD-ROM, an optical storage device, a magnetic storage device, a ROM (Read Only Memory), a PROM (Programmable Read Only Memory), an EPROM (Erasable Programmable Read Only Memory), an EEPROM (Electrically Erasable Programmable Read Only Memory) and a Flash memory. Further, it is expected that one of ordinary skill, notwithstanding possibly significant effort and many design choices motivated by, for example, available time, current technology, and economic considerations, when guided by the concepts and principles disclosed herein will be readily capable of generating such software instructions and programs and ICs with minimal experimentation. 
     The Abstract of the Disclosure is provided to allow the reader to quickly ascertain the nature of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. In addition, in the foregoing Detailed Description, it can be seen that various features are grouped together in various embodiments for the purpose of streamlining the disclosure. This method of disclosure is not to be interpreted as reflecting an intention that the claimed embodiments require more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive subject matter lies in less than all features of a single disclosed embodiment. Thus the following claims are hereby incorporated into the Detailed Description, with each claim standing on its own as a separately claimed subject matter.