Abstract:
Various exemplary embodiments relate to a method and related network node including one or more of the following: receiving a message at a PCRN; determining whether a policy decision should be made with regard to the received message; when a policy decision should be made: identifying a rule of a plurality of rules as applicable to processing the received message, wherein the identified rule specifies an action to be taken in response to the received message, performing the action in response to the received message; and when a policy decision should not be made, processing the received message according to normal procedures. Such action may include one or more of the following: rejecting a request, accepting a request, modifying a request, and performing a predefined routine.

Description:
TECHNICAL FIELD 
       [0001]    Various exemplary embodiments disclosed herein relate generally to policy and charging in telecommunications networks. 
       BACKGROUND 
       [0002]    As demand increases for varying types of applications within mobile telecommunications networks, service providers constantly upgrade their systems in order to reliably provide an 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. 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. 
         [0003]    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. 
         [0004]    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, and 3GPP TS 29.214 describe the policy and charging rules function (PCRF), policy and charging enforcement function (PCEF), and bearer binding and event reporting function (BBERF) of the EPC. 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. 
         [0005]    For example, 3GPP TS 29.212 and 3GPP TS 29.214 provide some guidance on the establishment of an application session by the EPC upon receipt of an application request from an application function (AF) in the form of an aa-request (AAR) message or from a packet data network gateway (PGW) in the form of a credit control request (CCR) message. The standards specify that the PCRF is responsible for receiving requests, establishing IP-CAN and gateway control sessions, creating new policy and charging control (PCC) rules commensurate with such requests, and providing these new PCC rules to the PCEF for installation. The 3GPP standards also define the format of various messages and PCC rules. 
         [0006]    The 3GPP standards do not, however, describe how the PCRF should interpret a request, establish sessions, or create PCC rules. Such functionality is desired for the operation of the EPC. Without an infrastructure to establish various sessions or create appropriate PCC rules based on a request, the EPC may not be able to provide service to user equipment, charge subscribers for application usage, or ensure that a certain QoE level is met in providing services. Indeed, the 3GPP standards fall short of describing how the PCRF should process and respond to the various possible messages that may be sent by an SGW, PGW, or AF. 
         [0007]    In view of the foregoing, it would be desirable to provide a flexible method of processing messages received at a PCRF. In particular, it would be desirable to provide a customizable process by which a PCRF may receive a message from another node and take appropriate action in response. 
       SUMMARY 
       [0008]    In light of the present need for a flexible method of processing messages received at a policy and charging rules node (PCRN), a brief summary of various exemplary embodiments is presented. 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. 
         [0009]    Various exemplary embodiments relate to a method, related network node, and related machine-readable storage medium including one or more of the following: receiving a message at a PCRN; determining whether a policy decision should be made with regard to the received message; when a policy decision should be made: identifying a rule of a plurality of rules as applicable to processing the received message, wherein the identified rule specifies an action to be taken in response to the received message, performing the action in response to the received message; and when a policy decision should not be made, processing the received message according to normal procedures. Such action may include one or more of the following: rejecting a request, accepting a request, modifying a request, and performing a predefined routine. 
         [0010]    Various alternative embodiments relate to a policy and charging rules node including one or more of the following: an interface that receives a message from another node; a rule storage that stores a plurality of rules, wherein at least one rule includes an indication of an action to be taken in response to the received message; a message handler configured to: determine that a policy decision should be made with regard to the message, and request a policy decision; and a policy decision engine that: determine that the at least one rule of the plurality of rules is applicable to a current context, and return the indication of the action to the message handler, wherein the message handler subsequently performs the action. 
         [0011]    According to the foregoing, various exemplary embodiments provide for the externalization of PCRN behavior. Particularly, by providing behavioral rules for determining what action a PCRN should take in response to a received message, a manufacturer or a user may define how a PCRN responds to a message under various circumstances. Thus, the behavior of a PCRN may be fine-tuned to handle differing situations in appropriate manners and may be updated to evolve with the network. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]    In order to better understand various exemplary embodiments, reference is made to the accompanying drawings, wherein: 
           [0013]      FIG. 1  illustrates an exemplary subscriber network for providing various data services; 
           [0014]      FIG. 2  illustrates an exemplary policy and charging rules node (PCRN) for providing externalized behavior; 
           [0015]      FIG. 3  illustrates an exemplary data arrangement for storing policy decision rules in the embodiment shown in  FIG. 2 ; 
           [0016]      FIG. 4  illustrates an exemplary data arrangement for storing predefined routines in the embodiment shown in  FIG. 2 ; 
           [0017]      FIG. 5  illustrates an exemplary method for processing a received message in accordance with an action indicated by a policy decision result in the embodiment shown in  FIG. 2 ; and 
           [0018]      FIG. 6  illustrates and exemplary method for performing a policy decision in the embodiment shown in  FIG. 2 . 
       
    
    
     DETAILED DESCRIPTION 
       [0019]    Referring now to the drawings, in which like numerals refer to like components or steps, there are disclosed broad aspects of various exemplary embodiments. 
         [0020]      FIG. 1  illustrates an exemplary subscriber network  100  for providing various data services. Exemplary subscriber network  100  may be a communications network, such as an LTE or 4G mobile communications network, for providing access to various services. The network  100  may include user equipment  110 , base station  120 , evolved packet core (EPC)  130 , packet data network  140 , and application function (AF)  150 . 
         [0021]    User equipment  110  may be a device that communicates with packet data network  140  for providing an 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, television set-top box, or any other device capable of communicating with other devices via EPC  130 . 
         [0022]    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. 
         [0023]    Evolved packet core (EPC)  130  may be a device or association 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 . 
         [0024]    Serving gateway (SGW)  132  may be a device that provides gateway access to the EPC  130  to an end user of network  100 . SGW  132  may be the first device within the EPC  130  that receives packets sent by user equipment  110 . SGW  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 (PMIP) 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). 
         [0025]    Packet data network gateway (PGW)  134  may be a device that provides gateway access to packet data network  140  to an end user of network  100 . 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. Upon receiving a request for an unknown application service from UE  110 , PGW may construct a credit control request (CCR), such as, for example, CCR  170 , requesting an appropriate allocation of resources and forward the request to PCRN  136 . 
         [0026]    It should be noted that while exemplary network  100  corresponds to one particular implementation of long term evolution (LTE), many variations may exist. For example, SGW  132  may not be present, PGW  134  may not be present, and/or the functions of SGW  132  and PGW  134  may be consolidated into a single device or spread across multiple additional devices. 
         [0027]    Policy and charging rules node (PCRN)  136  may be a device that receives requests related to service data flows (SDFs) and IP-CAN sessions, 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. PCRN  136  may receive an application request in the form of an aa-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 . 
         [0028]    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 a request in the form of a credit control request (CCR)  170  from SGW  132  or PGW  134 . As with AAR  160 , upon receipt of CCR  170 , PCRN may take appropriate action in response, such as, for example, generating at least one new PCC rule for fulfilling and/or responding to the CCR  170 . In various embodiments, AAR  160  and CCR  170  may represent two independent requests to be processed separately, while in other embodiments, AAR  160  and CCR  170  may carry information regarding a single request, and PCRN  136  may take action based on the combination of AAR  160  and CCR  170 . In various embodiments, PCRN  136  may be capable of handling both single-message and paired-message requests. 
         [0029]    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 quality of service (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. 
         [0030]    In processing various requests and other messages, PCRN  136  may make use of one or more behavioral rules, the details of which will be described below with reference to  FIGS. 2-6 . PCRN  136  may locate an applicable behavioral rule for a particular request, conflict, or event, and take at least one action specified by the applicable behavioral rule. In various embodiments, such a behavioral rule may include a reference to a predefined routine that the PCRN  136  may perform in response to a request or other message. 
         [0031]    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, for example, subscriber category, bandwidth limits, charging parameters, and subscriber priority. 
         [0032]    Packet data network  140  may be a network (e.g., the Internet or another network of communications devices) 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 . 
         [0033]    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 aa-request (AAR)  160  defined by 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 a subscriber using the application service and an identification of the particular service data flows desired to 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. 
         [0034]    Having described the components of subscriber network  100 , a brief summary of the operation of subscriber network  100  will be provided. It should be apparent that the following description is intended to provide an overview of the operation of subscriber network  100  and is therefore a simplification in some respects. The detailed operation of subscriber network  100  will be described in further detail below in connection with  FIGS. 2-6 . 
         [0035]    PCRN  136  may receive a request for establishment of a service data flow (SDF) such as, for example, AAR  160  and/or CCR  170 . In attempting to establish the requested SDF, PCRN  136  may determine that there is a conflict between the request and a subscriber profile. For example, the request may specify that 512 kbps of bandwidth is requested while a subscriber record may indicate that the subscriber is only allowed to have 256 kbps of bandwidth. To resolve this conflict, PCRN  136  may locate an applicable behavioral rule that indicates that the request should be rejected. Subsequently, PCRN  136  may reject the request in accordance with the applicable rule. 
         [0036]      FIG. 2  illustrates an exemplary policy and charging rules node (PCRN) for providing externalized behavior. PCRN  136  may include a Gxx interface  205 , a Gx interface  210 , an Rx interface  215 , a message handler  220 , a context information module  225 , a policy decision engine  230 , a rule storage  235 , a routine storage  240 , a user interface  245 , a rule manager  250 , and a routine manager  255 . 
         [0037]    Gxx interface  205  may be an interface comprising hardware and/or executable instructions encoded on a machine-readable storage medium configured to communicate with a SGW such as SGW  132 . Such communication may be implemented according to the 3GPP TS 29.212. Thus, Gxx interface  205  may receive requests for QoS rules and transmit QoS rules for installation. Gxx interface  205  may further receive UE-originated application requests, session requests, and event notifications in the form of a CCR. 
         [0038]    Gx interface  210  may be an interface comprising hardware and/or executable instructions encoded on a machine-readable storage medium configured to communicate with a PGW such as PGW  134 . Such communication may be implemented according to the 3GPP TS 29.212. Thus, Gx interface  210  may receive requests for PCC rules and transmit PCC rules for installation. Gx interface  210  may further receive UE-originated application requests, session requests, and event notifications in the form of a CCR. 
         [0039]    Rx interface  215  may be an interface comprising hardware and/or executable instructions encoded on a machine-readable storage medium configured to communicate with AF  150 . Such communication may be implemented according to the 3GPP TS 29.214. For example, Rx interface  215  may receive application requests, session requests, and event notifications in the form of an AAR. 
         [0040]    Message handler  220  may include hardware and/or executable instructions on a machine-readable storage medium configured to process application and session requests received via Gxx interface  205 , GX interface  210 , and Rx interface  215 . For example, message handler  220  may create and install new PCC rules in response to an application request. As a further example, message handler  220  may establish, modify, or terminate IP-CAN sessions and gateway control sessions in response to a session request. After fully processing a message, message handler  220  may construct and transmit a message over Gxx interface  205 , GX interface  210 , and/or Rx interface  215  to notify other nodes as to the result of processing the message. For example, if message handler  220  creates a new PCC rule in response to a request message, it may construct a reauthorization request (RAR) message to push the new PCC rule to an appropriate PGW. 
         [0041]    In processing various messages, message handler  220  may request a policy decision from policy decision engine  230  and base at least part of its response to the message on the policy decision results. Message handler  220  may provide context information from the message to policy decision engine  230 , either directly or via context information module  225 . Policy decision results may include an indication of an action that the message handler  220  should take in response to the message, in which case message handler may perform the specified action. Alternatively or additionally, policy decision results may include an indication of a predefined routine. In such a case, message handler  220  may retrieve the predefined routine from routine storage  240  and subsequently perform the routine. As will be described in further detail with reference to  FIG. 4  below, such a predefined routine may include one or more steps or actions to be taken by the message handler  220 . 
         [0042]    Context information module  225  may include hardware and/or executable instructions on a machine-readable storage medium configured to provide various context information to policy decision engine  230 . For example, context information module  225  may store information carried by a received message. Context information module  225  may further store previously received and/or transmitted messages associated with a subscriber, session, and/or service data flow. Context information module  225  may further access information stored elsewhere such as, for example, subscriber information stored in an SPR such as SPR  138 . 
         [0043]    Policy decision engine  230  may include hardware and/or executable instructions on a machine-readable storage medium configured to identify rules stored in rule storage  235  that are applicable to a received message or current context. As will be described in further detail below with respect to  FIG. 3 , each rule may include a criteria section which indicates when a rule is applicable. Policy decision engine  230  may compare this criteria section to context information passed by message handler  220  and/or retrieved from context information module  225 . Upon locating an applicable rule, policy decision engine  230  may return the results portion of the rule to message handler  220 . 
         [0044]    Rule storage  235  may be any machine-readable medium capable of storing policy decision rules for use by policy decision engine  230 . Accordingly, rule storage  235  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. In various alternative embodiments, rule storage  235  may be a device that is external to PCRN  136 . As will be described in further detail below with respect to  FIG. 3 , rule storage  235  may store definitions of numerous policy decision rules. 
         [0045]    Routine storage  240  may be any machine-readable medium capable of storing predefined routines for use by message handler  220 . Accordingly, routine storage  240  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. Routine storage  240  may be an independent storage device or may be the same as rule storage  235 . In various alternative embodiments, routine storage  240  may be a device that is external to PCRN  136 . As will be described in further detail below with respect to  FIG. 4 , routine storage  245  may store definitions of numerous predefined routines. Such definitions may include, for example, a name, conditional statements, and/or indications of actions to be taken. 
         [0046]    User interface  245  may include hardware and/or executable instructions on a machine-readable storage medium configured to provide a user with access to PCRN  136 . User interface  245  may receive input from a user and may include hardware such as, for example, a keyboard and/or mouse. User interface  245  may also display information as output to the user and may include, for example, a monitor. A user may access rule manager  250  and/or routine manager  255  via user interface  245 . 
         [0047]    Rule manager  250  may include hardware and/or executable instructions on a machine-readable storage medium configured to define, modify, and otherwise manage policy decision rules. For example, rule manager  250  may receive a definition of a new policy decision rule via user interface  245 , format the definition according to a standard policy decision rule syntax used by PCRN  136 , and store the definition in rule storage  235 . Rule manager  250  may further provide a definition of an existing policy decision rule to a user upon request via user interface  245 . Rule manager  250  may subsequently receive a modified rule definition, format the definition if necessary, and store the definition in rule storage  235 . In storing a modified definition, rule manager  250  may overwrite an existing definition or store the modified definition as a new version of the policy decision rule while preserving the old definition. Thus, rule manager  250  may provide version control functionality. 
         [0048]    Routine manager  255  may include hardware and/or executable instructions on a machine-readable storage medium configured to define, modify, and otherwise manage routines. For example, routine manager  255  may receive a definition of a new routine via user interface  250 , format the definition according to a standard routine syntax used by PCRN  136 , and store the definition in routine storage  240 . Routine manager  255  may further provide a definition of an existing routine to a user upon request via user interface  250 . Routine manager  255  may subsequently receive a modified routine definition, format the definition if necessary, and store the definition in routine storage  240 . In storing a modified definition, routine manager  255  may overwrite an existing definition or store the modified definition as a new version of the routine while preserving the old definition. Thus, routine manager  255  may provide version control functionality. 
         [0049]      FIG. 3  illustrates an exemplary data arrangement  300  for storing policy decision rules. Data arrangement  300  may be, for example, a table in a database stored in rule storage  235  ( FIG. 2 ), SPR  138  ( FIG. 1 ), or another node (not shown) within EPC  130  ( FIG. 1 ). Alternatively, data arrangement  300  could be a series of linked lists, an array, or a similar data structure. Thus, it should be apparent that data arrangement  300  is an abstraction of the underlying data; any data structure suitable for storage of the underlying data may be used. 
         [0050]    Data arrangement  300  may include various rule sets for use in policy decisions related to various types of messages and in other contexts. Rule sets may be defined based on various context aspects. For example, each rule set may be defined to apply to certain received messages such as an IP-CAN modification request or service data flow request. Additionally or alternatively, rules sets may be defined to apply to particular conflicts or events that may prompt the request for a policy decision function such as, for example, the loss of a bearer, a request for more resources than are available, or a request for more resources than are allowed for a particular subscriber. 
         [0051]    In the example of data arrangement  300 , rule set  310  may include rules applicable when a subscriber has requested more bandwidth than the subscriber is allowed. It should be noted that rule set  310  is a simplification in some respects. For example, rule set  310  may be applicable to requests for one or more of the following: aggregate maximum bandwidth, maximum bandwidth, and guaranteed bandwidth. Data arrangement  300  may include additional rule sets  320 . 
         [0052]    Rule set  310  may include a number of rules  312 ,  314 ,  316 ,  318 . Each rule may include a criteria section for use in determining whether the rule is applicable and a result section for indicating an action to be taken if the rule is applicable. As an example, rule  312  indicates that it is applicable when the subscriber category is ‘silver.’ It should be noted that the exemplary criteria section is in some respects a simplification and that various implementations may use additional and/or alternative conditions for application of a rule. Rule  312  further indicates that, when applicable, the PCRN  136  should reject the message being processed. 
         [0053]    A result section may indicate more than one action to be taken by a PCRN such as PCRN  136 . As an example, rule  314  may indicate that it is applicable when the subscriber category is ‘gold.’ When applicable, rule  314  indicates that the request should be first resized such that it would not create a conflict. Rule  314  further indicates that the resized request should be returned to the requesting node as a counteroffer. Thereafter, the requesting node may submit an additional request in accordance with the counter offer which the PCRN  136  may process as a new request. 
         [0054]    In various embodiments, a rule may indicate a predefined routine that the PCRN  136  should follow in responding to the message. Thus, rule  316  indicates that it is applicable when the subscriber category is ‘platinum,’ and that the PCRN should perform a routine having the name PLAT_BW in responding to the current message. As will be described in further detail with respect to  FIG. 4  below, PLAT_BW may include indications of actions to be taken and/or instructions to be executed by the PCRN  136 . Rule set  310  may include additional rules  318 . 
         [0055]      FIG. 4  illustrates an exemplary data arrangement  400  for storing predefined routines. Data arrangement  400  may be, for example, a table in a database stored in routine storage  240  ( FIG. 2 ), SPR  138  ( FIG. 1 ), or another node (not shown) within EPC  130  ( FIG. 1 ). Alternatively, data arrangement  400  could be a series of linked lists, an array, or a similar data structure. Thus, it should be apparent that data arrangement  400  is an abstraction of the underlying data; any data structure suitable for storage of the underlying data may be used. 
         [0056]    Data arrangement  400  may include a routine  410  and additional routines  420 . In various embodiments, routines  410 ,  420  may be organized within routine sets (not shown) similar to the rule sets  310 ,  320  used in data arrangement  300  ( FIG. 3 ). In such embodiments, rules within a particular rule set can reference those routines within the corresponding routine set. In other embodiments, data arrangement  400  may not include routine sets, and any rule may be able to reference any routine, regardless of the rule set to which the rule belongs. 
         [0057]    Routine  410  may be identified as “PLAT_BW,” and may contain instructions for execution by the PCRN  136 . It should be noted that the particular routine  410  is defined in terms of pseudocode. In various implementations, routine  410  may contain compiled instructions, interpreted instructions, and/or enumerated actions to be taken similar to those used in exemplary rules  312 ,  314 . Thus, predefined routines such as routines  410 ,  420  may be of any complexity, including single step routines. Routine  410  may indicate that PCRN  136  should compare the requested bandwidth to the bandwidth allowed for the relevant subscriber. Such allowed bandwidth may be retrieved from, for example, a record stored in an SPR such as SPR  138 . If the requested bandwidth does not exceed the allowed bandwidth by more than 128 kb, then the PCRN  136  should simply create a PCC rule according to the request. If, on the other hand, the requested bandwidth exceeds the allowed bandwidth by more than 128 kb, then the PCRN  136  should create a PCC rule according to the request with the exception that the allowed bandwidth should be used instead of the requested bandwidth. Finally, the PCRN  136  should push the new PCC rule to the relevant PGW for installation. 
         [0058]      FIG. 5  illustrates an exemplary method  500  for processing a received message in accordance with an action indicated by a policy decision result. Method  500  may be performed by the components of PCRN  136  and/or PCRN  136  such as, for example, message handler  220 . 
         [0059]    Method  500  may begin in step  505  and proceed to  510  where PCRN  136  may receive a message via Gxx interface  205 , Gx interface  210 , and/or Rx interface  215 . Method  500  may then proceed to step  515 , where PCRN  136  may determine whether a policy decision should be made in order to process the received message. For example, PCRN  136  may determine that a requested parameter conflicts with a subscriber record or the currently available resources. Alternatively, PCRN  136  may determine that the message is of a type or contains an indication of an event for which a policy decision is necessary. If such a policy decision is necessary, method  500  may proceed to step  520 ; otherwise method  500  may proceed to step  565 . 
         [0060]    PCRN  136  may invoke a policy decision in step  520  and then receive a policy decision result in step  525 . Method  500  may then proceed to step  530  where PCRN  136  may determine whether the received result includes an indication of a predefined routine. If so, PCRN  136  may retrieve the specified routine in step  535  and perform the steps specified by the routine in step  540 . 
         [0061]    If, on the other hand, the result does not contain a routine reference, method  500  may proceed from step  530  to step  555 , where PCRN  136  may determine whether the result indicates an action to be taken. If the result does indicate an action, PCRN  136  may perform the action in step  560  and proceed to step  565 . If the result does not indicate an action, PCRN  136  may take other appropriate steps (not shown) and proceed directly to step  565 . 
         [0062]    At step  565 , PCRN  136  may finish processing the message. For example, PCRN  136  may complete a response message and send it to the requesting node, if this has not been done already. Alternatively, if all processing has already been completed through the processing of a rule, PCRN  136  may do nothing at step  565 . Method  500  may then end in step  570 . 
         [0063]      FIG. 6  illustrates and exemplary method  600  for performing a policy decision. Method  600  may be performed by the components of PCRN  136  and/or PCRN  136  such as, for example, policy decision engine  230 . Method  600  may correspond to step  520  ( FIG. 5 ) or may be performed in parallel to method  500  after the execution of step  520 . 
         [0064]    Method  600  may begin in step  605  and proceed to step  610  where PCRN  136  may retrieve a first rule from the applicable rule set. PCRN  136  may determine the applicable rule set from context information stored in context information module  225  or message handler  220  may specify a rule set when invoking a policy decision. After retrieving a first rule, method  600  may proceed to step  615 . 
         [0065]    At step  615 , PCRN  136  may compare the criteria portion of the rule to relevant context information passed by message handler  220  and/or context information module  225 . If the criteria does not match the context information, method  600  may proceed to step  620  where PCRN  136  may retrieve the next rule from rule storage  230 . Method  600  may then loop back to step  615 . 
         [0066]    If, on the other hand, PCRN  136  determines that the criteria section of a rule matches the context information at step  615 , method  600  may proceed to step  625 . At step  625 , PCRN  136  may retrieve the result from the result section of the matching rule. Method  600  may then proceed to step  630  where PCRN  136  may return the rule result for further processing. Method  600  may then end in step  635 . 
         [0067]    Having described exemplary components and methods for the operation of exemplary subscriber network  100  and PCRN  136 , an example of the operation of exemplary network  100  and PCRN  136  will now be provided with reference to  FIGS. 1-6 . PCRN  136  may correspond to PCRN  136 . The contents of rule storage  235  may be indicated by data arrangement  300  and the contents of routine storage  240  may be indicated by data arrangement  400 . 
         [0068]    The process may begin when PCRN  136  receives CCR  170  requesting the establishment of a new service data flow with 512 kbps bandwidth. Message handler  220  then attempts to create a PCC rule establishing the data flow but determines in step  515  that the subscriber is only allowed to have 256 kbps bandwidth. Message handler  220  then requests a policy decision from policy decision engine  230  in step  520 , indicating that rule set  310  should be used. 
         [0069]    Policy decision engine  230  retrieves rule  312  in step  610 . Since the criteria section uses the subscriber_cat variable, policy decision engine  230  may request this information from context information module  225 . Context information module, in turn, may retrieve the record associated with the subscriber ID from SPR  138  and determine that subscriber_cat is “gold.” Policy decision engine  230  then determines that rule  312  is not applicable at step  615  because “gold” does not match “silver.” Policy decision engine  230  then retrieves rule  314  at step  620 . Since the criteria of rule  314  specifies that the rule is applicable when subscriber_cat is “gold,” policy decision engine  230  determines that rule  314  is applicable in step  615 , extracts the result ‘Resize; Counter’ from rule  314  in step  625 , and returns the result in step  630 . 
         [0070]    Message handler  220  receives the result in step  525  and determines that the result is not a routine identifier in step  530 . Then, in step  555 , message handler  220  determines that the result indicates an action to be taken. Message handler  220  then resizes the request according to the allowed bandwidth for the subscriber and sends it as a counteroffer to PGW  134  in step  560 , as specified by rule  314 . PCRN  136  may determine that no further action should be taken at this time in step  565 , since the counteroffer has already been sent. 
         [0071]    According to the foregoing, various exemplary embodiments provide for the externalization of PCRN behavior. Particularly, by providing behavioral rules for determining what action a PCRN should take in response to a received message, a manufacturer or a user may define how a PCRN responds to a message under various circumstances. Thus, the behavior of a PCRN may be fine-tuned to handle differing situations in appropriate manners and may be updated to evolve with the network. 
         [0072]    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 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. 
         [0073]    It should be appreciated by those skilled in the art that any block diagrams herein represent conceptual views of illustrative circuitry embodying the principals 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. 
         [0074]    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 affected 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.