Abstract:
Various exemplary embodiments relate to a method performed by a policy and charging rules node (PCRN) for processing a change in a status of a roaming partner, the method including: receiving, at the PCRN, a message indicating a change in a status of the roaming partner; identifying roaming subscriber sessions associated with the roaming partner; determining home based roaming subscriber sessions among the identified subscriber sessions; marking the determined home based roaming subscriber sessions for termination; and sending a termination message to a policy and charging enforcement node for the determined home based roaming subscriber sessions.

Description:
TECHNICAL FIELD 
     Various exemplary embodiments disclosed herein relate generally to telecommunications networks. 
     BACKGROUND 
     As the demand increases for varying types of applications within mobile telecommunications networks, service providers must constantly upgrade their systems in order to reliably provide this expanded functionality. What was once a system designed simply for voice communication has grown into an all-purpose network access point, providing access to a myriad of applications including text messaging, multimedia streaming, and general Internet access. In order to support such applications, providers have built new networks on top of their existing voice networks, leading to a less-than-elegant solution. As seen in second and third generation networks, voice services must be carried over dedicated voice channels and directed toward a circuit-switched core, while other service communications are transmitted according to the Internet Protocol (IP) and directed toward a different, packet-switched core. This led to unique problems regarding application provision, metering and charging, and quality of experience (QoE) assurance. 
     In an effort to simplify the dual core approach of the second and third generations, the 3rd Generation Partnership Project (3GPP) has recommended a new network scheme it terms “Long Term Evolution” (LTE). In an LTE network, all communications are carried over an IP channel from user equipment (UE) to an all-IP core called the Evolved Packet Core (EPC). The EPC then provides gateway access to other networks while ensuring an acceptable QoE and charging a subscriber for their particular network activity. 
     The 3GPP generally describes the components of the EPC and their interactions with each other in a number of technical specifications. Specifically, 3GPP TS 29.212, 3GPP TS 29.213, 3GPP TS 29.214, and 3GPP TS 29.215 describe the Policy and Charging Rules Function (PCRF), Policy and Charging Enforcement Function (PCEF), Bearer Binding and Event Reporting Function (BBERF) of the EPC, and Policy and Charging Control (PCC) Over S9 Reference Point. These specifications further provide some guidance as to how these elements interact in order to provide reliable data services and charge subscribers for use thereof. 
     SUMMARY 
     A brief summary of various exemplary embodiments is presented below. Some simplifications and omissions may be made in the following summary, which is intended to highlight and introduce some aspects of the various exemplary embodiments, but not to limit the scope of the invention. Detailed descriptions of a preferred exemplary embodiment adequate to allow those of ordinary skill in the art to make and use the inventive concepts will follow in later sections. 
     Various exemplary embodiments relate to a method performed by a policy and charging rules node (PCRN) for processing a change in a status of a roaming partner, the method including: receiving, at the PCRN, a message indicating a change in a status of the roaming partner; identifying roaming subscriber sessions associated with the roaming partner; determining home based roaming subscriber sessions among the identified subscriber sessions; marking the determined home based roaming subscriber sessions for termination; and sending a termination message to a policy and charging enforcement node for the determined home based roaming subscriber sessions. 
     Various exemplary embodiments relate to a method performed by a visited policy and charging rules node (PCRN) for processing a change in a status of a roaming partner, the method including: receiving, at the visited PCRN, a message indicating a change in a status of the roaming partner; determining visited based roaming subscriber sessions among the identified subscriber sessions; marking the determined visited based roaming subscriber sessions for termination; and sending a termination message to a visited policy and charging enforcement node for the determined visited based roaming subscriber sessions. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In order to better understand various exemplary embodiments, reference is made to the accompanying drawings, wherein: 
         FIG. 1  illustrates an exemplary subscriber network for providing various data services; 
         FIG. 2  illustrates an exemplary subscriber network  200  for providing roaming access to various data services; 
         FIG. 3  illustrates an embodiment of a PCRN; 
         FIG. 4  is a block diagram illustrating a method for the termination of roaming sessions on a home PCRN; 
         FIG. 5  is a diagram illustrating the flow of messages associated with the termination of roaming session on a home PCRN; 
         FIG. 6  is a block diagram illustrating a method for the termination of roaming sessions on a visited PCRN; and 
         FIG. 7  is a diagram illustrating the flow of messages associated with the termination of roaming session on a visited PCRN. 
     
    
    
     To facilitate understanding, identical reference numerals have been used to designate elements having substantially the same or similar structure and/or substantially the same or similar function. 
     DETAILED DESCRIPTION 
     When a subscriber roams onto a roaming network, a connection may be made between a visited policy and charging rule node (PCRN) and a home PCRN to control the usage of the visited and home network by the subscriber. The subscriber&#39;s ability to roam on visited networks depends on roaming agreements between network providers. These roaming agreements may specify various operating parameters for a subscriber when roaming on the visited network of the roaming partner. A roaming agreement may be between two or more network partners. When roaming agreement is deleted, a roaming partner is deleted, or a roaming partner is removed from a roaming agreement, existing sessions may need to be terminated. In view of the foregoing, it would be desirable to provide a method of terminating sessions on both home and visited networks when a change occurs in a roaming relationship between two partner networks. 
     Referring now to the drawings, in which like numerals refer to like components or steps, there are disclosed broad aspects of various exemplary embodiments. 
       FIG. 1  illustrates an exemplary subscriber network  100  for providing various data services. In various embodiments, subscriber network  100  may be a public land mobile network (PLMN). Exemplary subscriber network  100  may be telecommunications network or other network for providing access to various services. Exemplary subscriber network  100  may include user equipment  110 , base station  120 , evolved packet core (EPC)  130 , packet data network  140 , and application function (AF)  150 . 
     User equipment  110  may be a device that communicates with packet data network  140  for providing the end-user with a data service. Such data service may include, for example, voice communication, text messaging, multimedia streaming, and Internet access. More specifically, in various exemplary embodiments, user equipment  110  is a personal or laptop computer, wireless email device, cell phone, tablet, television set-top box, or any other device capable of communicating with other devices via EPC  130 . 
     Base station  120  may be a device that enables communication between user equipment  110  and EPC  130 . For example, base station  120  may be a base transceiver station such as an evolved nodeB (eNodeB) as defined by 3GPP standards. Thus, base station  120  may be a device that communicates with user equipment  110  via a first medium, such as radio waves, and communicates with EPC  130  via a second medium, such as Ethernet cable. Base station  120  may be in direct communication with EPC  130  or may communicate via a number of intermediate nodes (not shown). In various embodiments, multiple base stations (not shown) may be present to provide mobility to user equipment  110 . Note that in various alternative embodiments, user equipment  110  may communicate directly with EPC  130 . In such embodiments, base station  120  may not be present. 
     Evolved packet core (EPC)  130  may be a device or network of devices that provides user equipment  110  with gateway access to packet data network  140 . EPC  130  may further charge a subscriber for use of provided data services and ensure that particular quality of experience (QoE) standards are met. Thus, EPC  130  may be implemented, at least in part, according to the 3GPP TS 29.212, 29.213, and 29.214 standards. Accordingly, EPC  130  may include a serving gateway (SGW)  132 , a packet data network gateway (PGW)  134 , a policy and charging rules node (PCRN)  136 , and a subscription profile repository (SPR)  138 . 
     Serving gateway (SGW)  132  may be a device that provides gateway access to the EPC  130 . SGW  132  may be one of the first devices within the EPC  130  that receives packets sent by user equipment  110 . Various embodiments may also include a mobility management entity (MME) (not shown) that receives packets prior to SGW  132 . GW  132  may forward such packets toward PGW  134 . SGW  132  may perform a number of functions such as, for example, managing mobility of user equipment  110  between multiple base stations (not shown) and enforcing particular quality of service (QoS) characteristics for each flow being served. In various implementations, such as those implementing the Proxy Mobile IP standard, SGW  132  may include a Bearer Binding and Event Reporting Function (BBERF). In various exemplary embodiments, EPC  130  may include multiple SGWs (not shown) and each SGW may communicate with multiple base stations (not shown). 
     Packet data network gateway (PGW)  134  may be a device that provides gateway access to packet data network  140 . PGW  134  may be the final device within the EPC  130  that receives packets sent by user equipment  110  toward packet data network  140  via SGW  132 . PGW  134  may include a policy and charging enforcement function (PCEF) that enforces policy and charging control (PCC) rules for each service data flow (SDF). Therefore, PGW  134  may be a policy and charging enforcement node (PCEN). PGW  134  may include a number of additional features such as, for example, packet filtering, deep packet inspection, and subscriber charging support. PGW  134  may also be responsible for requesting resource allocation for unknown application services. 
     Policy and charging rules node (PCRN)  136  may be a device or group of devices that receives requests for application services, generates PCC rules, and provides PCC rules to the PGW  134  and/or other PCENs (not shown). PCRN  136  may be in communication with AF  150  via an Rx interface. As described in further detail below with respect to AF  150 , PCRN  136  may receive an application request in the form of an Authentication and Authorization Request (AAR)  160  from AF  150 . Upon receipt of AAR  160 , PCRN  136  may generate at least one new PCC rule for fulfilling the application request  160 . 
     PCRN  136  may also be in communication with SGW  132  and PGW  134  via a Gxx and a Gx interface, respectively. PCRN  136  may receive an application request in the form of a credit control request (CCR) (not shown) from SGW  132  or PGW  134 . As with AAR  160 , upon receipt of a CCR, PCRN may generate at least one new PCC rule for fulfilling the application request  170 . In various embodiments, AAR  160  and the CCR may represent two independent application requests to be processed separately, while in other embodiments, AAR  160  and the CCR may carry information regarding a single application request and PCRN  136  may create at least one PCC rule based on the combination of AAR  160  and the CCR. In various embodiments, PCRN  136  may be capable of handling both single-message and paired-message application requests. 
     Upon creating a new PCC rule or upon request by the PGW  134 , PCRN  136  may provide a PCC rule to PGW  134  via the Gx interface. In various embodiments, such as those implementing the PMIP standard for example, PCRN  136  may also generate QoS rules. Upon creating a new QoS rule or upon request by the SGW  132 , PCRN  136  may provide a QoS rule to SGW  132  via the Gxx interface. 
     Subscription profile repository (SPR)  138  may be a device that stores information related to subscribers to the subscriber network  100 . Thus, SPR  138  may include a machine-readable storage medium such as read-only memory (ROM), random-access memory (RAM), magnetic disk storage media, optical storage media, flash-memory devices, and/or similar storage media. SPR  138  may be a component of PCRN  136  or may constitute an independent node within EPC  130 . Data stored by SPR  138  may include an identifier of each subscriber and indications of subscription information for each subscriber such as bandwidth limits, charging parameters, and subscriber priority. 
     Packet data network  140  may be any network for providing data communications between user equipment  110  and other devices connected to packet data network  140 , such as AF  150 . Packet data network  140  may further provide, for example, phone and/or Internet service to various user devices in communication with packet data network  140 . 
     Application function (AF)  150  may be a device that provides a known application service to user equipment  110 . Thus, AF  150  may be a server or other device that provides, for example, a video streaming or voice communication service to user equipment  110 . AF  150  may further be in communication with the PCRN  136  of the EPC  130  via an Rx interface. When AF  150  is to begin providing known application service to user equipment  110 , AF  150  may generate an application request message, such as an authentication and authorization request (AAR)  160  according to the Diameter protocol, to notify the PCRN  136  that resources should be allocated for the application service. This application request message may include information such as an identification of the subscriber using the application service, an IP address of the subscriber, an APN for an associated IP-CAN session, and/or an identification of the particular service data flows that must be established in order to provide the requested service. AF  150  may communicate such an application request to the PCRN  136  via the Rx interface. 
       FIG. 2  illustrates an exemplary subscriber network  200  for providing roaming access to various data services. Exemplary subscriber network  200  may correspond to exemplary network  100 . EPC  230   v  may provide visited access to packet data network  240  for roaming UEs such as UE  210 , whereby traffic associated with UE  210  flows through SGW  232   v  and PGW  234   v . In various embodiments, EPC  230   v  and EPC  230   h  may connect to the same packet data network  240  (as shown) or may connect to two independent networks (not shown). Alternatively or additionally, EPC  230   v  may provide home-routed access to packet data network  240  for roaming UEs such as UE  210 , whereby traffic associated with UE  210  flows through SGW  232   v  and PGW  234   h . Accordingly, SGW  232   v  may be in communication with PGW  234   h . Likewise, SGW  232   h  may be in communication with PGW  234   v , such that EPC  230   h  may provide similar access to other roaming UEs (not shown) attached to base station  220   h.    
     UE  210  may be in communication with a base station  220   v  but outside the range of base station  220   h . Base station  220   v , however, may not connect to a home public land mobile network (HPLMN) for the UE  210 . Instead, base station  220   v  may belong to a visited public land mobile network (VPLMN) of the UE  210  and, as such, may not have access to various data associated with the UE  210 , a subscriber associated therewith, and/or other data useful or necessary in providing connectivity to UE  210 . For example, SPR  238   v  may not include information associated with UE  210 ; instead, such information may be stored in SPR  238   h . To enable the provision of service based on subscriber information stored in SPR  238   h , PCRN  236   v  may communicate with PCRN  236   h  via an S9 session. 
     In various embodiments, PCRN  236   v  may forward requests associated with UE  210  to PCRN  236   h  via an S9 session. PCRN  236   h  may process these messages to, for example, generate PCC and/or QoS rules. PCRN  236   h  may then forward these rules to PCRN  236   v  for installation on PGW  234   v  and/or SOW  232   v . In the case of home-routed access, PCRN  236   h  may also install PCC rules directly on PGW  234   h . In view of the cooperative nature of PCRNs  236   h ,  236   v , these devices may be referred to as “partner devices” with respect to each other. 
     In various embodiments, each partner device may be capable of operating as a home device and a visited device. For example, if another roaming UE (not shown) were attached to base station  220   h , PCRN  236   h  may be additionally capable of forwarding requests to PCRN  236   v  and PCRN  236   v  may be capable of returning appropriate rules to PCRN  236   h  for installation. 
     In establishing an S9 session, PCRNs  236   h ,  236   v  may be configured to negotiate a set of features that will be supported for the session. In various embodiments, PCRNs  236   h ,  236   v  may each be configured to perform this negotiation with respect to a default set of features such as, for example, the set of all features supported by the device. In such embodiments, the negotiated set of supported features may simply be the set of all features supported by both devices. 
       FIG. 3  illustrates an embodiment of a PCRN. The PCRN  300  may correspond to PCRN  136 , PCRN  236   h , or PCRN  236   v . The PCRN  300  may include an interface  310 , a common service blade (CSB)  320  and a plurality of PCRN blades  330 ,  332 , and  334 . The interface  310  may interface with various other nodes in the EPC  130  and may include various interfaces, for example, Sp, Rx, Gx, or Gxx. The PCRN blades  330 ,  332 , and  334  may include all of the typical policy and rules functions that may be performed by a PCRN. The CSB  320  may implement a Diameter proxy agent (DPA) and other interface functions for the PCRN blades  330 ,  332 , and  334 . Further, some of the functionality for terminating sessions as described below may be implemented in the CSB  320 . The CSB  320  and the PCRN blades  220 ,  332 , and  334  may be servers, processors, or other computing hardware in combination with software to implement the functions that these devices may be tasked to carry out. 
       FIG. 4  is a block diagram illustrating a method for the termination of roaming sessions on a home PCRN.  FIG. 5  is a diagram illustrating the flow of messages associated with the termination of roaming session on a home PCRN. The method  400  begins at  405 . Next, the home PCRN  590  may receive a change in roaming partner message  410  and  510 . The change in roaming partner message may indicate that a roaming partner has been deleted, that a roaming agreement has been deleted, or that a roaming partner has been removed from a roaming agreement. Next, the home PCRN  590  may identify all IP-CAN and S9 sessions associated with the roaming partner  415  and  515 . If a roaming agreement is deleted then this step will include identifying sessions associated with all roaming partners identified by the deleted roaming agreement. 
     The home PCRN  590  may then identify all home based IP-CAN and S9 sessions  420  and  520 . Home based IP-CAN and S9 sessions may be sessions that use the home PCEN  595  for the enforcement of policies and rules. Next, the home PCRN  590  may determine if the change in roaming partner message indicates that a roaming partner is deleted  425 . If so, then the home PCRN  590  may mark the identified IP-CAN and S9 sessions as terminating  430  and  525 . 
     If the change in roaming partner message did not indicate that a roaming partner is deleted, then the method may proceed to step  440 . 
     Next, the home PCRN  590  may identify all visited based IP-CAN and S9 sessions  440  and  540 . Visited based IP-CAN and S9 sessions may be sessions that use the visited PCEN  580  for the enforcement of policies and rules. The home PCRN  590  then may send S9 RAR messages over the S9 interface to terminate all the identified visited based IP-CAN and S9 sessions  445  and  545 . This may occur in two steps where the S9 subsessions are first terminated, and then the S9 session is terminated once all of its subsessions are terminated. The visited PCRN  585  may then mark the identified visited IP-CAN sessions and S9 sessions as terminating  450  and  550 . The visited PCRN  585  may then send Gx RARs to the visited PCEN  580  to cancel the identified visited IP-CAN sessions  455  and  555 . The visited PCEN  580  upon termination of the sessions may send a Gx RAA message to the visited PCRN  585  indicating that the IP-CAN sessions have been terminated  560 . Finally, the visited PCRN  585  may send S9 RAAs to the home PCRN indicating that the visited based IP-CAN sessions have been terminated. 
     While the home based IP-CAN sessions are marked for termination, the home PCRN  590  may continue to send and receive Gx and/or Gxx messages until the home PCEN  595  indicates that the IP-CAN session has been terminated. Similarly, the home PCRN  590  may continue to receive S9 messages related to the IP-CAN sessions marked as terminating until the home PCEN  595  indicates that the associated IP-CAN session has been terminated. 
     The home PCRN  590  may also continue to service IP-CAN and S9 sessions associated with roaming partners that have been removed from a roaming agreement or associated with deleted roaming agreements. Also, the home PCRN  590  may reject any new S9 session requests associated with a deleted roaming partner. 
       FIG. 6  is a block diagram illustrating a method for the termination of roaming sessions on a visited PCRN.  FIG. 7  is a diagram illustrating the flow of messages associated with the termination of roaming session on a visited PCRN. The method  600  begins at  605 . Next, the visited PCRN  785  may receive a change in roaming partner message  610  and  710 . The change in roaming partner message may indicate that a roaming partner has been deleted, that a roaming agreement has been deleted, or that a roaming partner has been removed from a roaming agreement. Next, the visited PCRN  785  may identify all IP-CAN and S9 sessions associated with the roaming partner  615  and  715 . If a roaming agreement is deleted then this step will include identifying sessions associated with all roaming partners identified by the deleted roaming agreement. 
     Next, the visited PCRN  785  may mark the identified IP-CAN and S9 sessions as terminating  620  and  720 . Now the visited PCRN  785  may send Gx RARs to the visited PCEN  780  to cancel the IP-CAN sessions marked as terminating  625  and  725 . The visited PCEN  780  upon termination of the sessions may send a Gx RAA message to the visited PCRN  785  indicating that the IP-CAN sessions have been terminated  630  and  730 . 
     While the visited based IP-CAN sessions are marked for termination, the visited PCRN  785  may continue to send and receive Gx and/or Gxx messages until the visited PCEN  780  indicates that the IP-CAN session has been terminated. Similarly, the visited PCRN  785  may continue to receive S9 messages related to the IP-CAN sessions marked as terminating until the visited PCEN  780  indicates that the associated IP-CAN session has been terminated. 
     Also, the visited PCRN  785  may reject any new S9 session requests associated with a deleted roaming partner, a roaming partner removed from a roaming agreement, or roaming partner associated with a deleted roaming agreement. 
     It should be apparent from the foregoing description that various exemplary embodiments of the invention may be implemented in hardware and/or firmware. Furthermore, various exemplary embodiments may be implemented as instructions stored on a machine-readable storage medium, which may be read and executed by at least one processor to perform the operations described in detail herein. A machine-readable storage medium may include any mechanism for storing information in a form readable by a machine, such as a personal or laptop computer, a server, or other computing device. Thus, a tangible and non-transitory machine-readable storage medium may include read-only memory (ROM), random-access memory (RAM), magnetic disk storage media, optical storage media, flash-memory devices, and similar storage media. 
     It should be appreciated by those skilled in the art that any block diagrams herein represent conceptual views of illustrative circuitry embodying the principles of the invention. Similarly, it will be appreciated that any flow charts, flow diagrams, state transition diagrams, pseudo code, and the like represent various processes which may be substantially represented in machine readable media and so executed by a computer or processor, whether or not such computer or processor is explicitly shown. 
     Although the various exemplary embodiments have been described in detail with particular reference to certain exemplary aspects thereof, it should be understood that the invention is capable of other embodiments and its details are capable of modifications in various obvious respects. As is readily apparent to those skilled in the art, variations and modifications can be effected while remaining within the spirit and scope of the invention. Accordingly, the foregoing disclosure, description, and figures are for illustrative purposes only and do not in any way limit the invention, which is defined only by the claims.