Abstract:
The invention is directed to providing a method and apparatus for authorizing Quality of Service (QoS) at a Policy and Charging Rules Function (PCRF) node in response to receiving a service request for a subscriber having a requested QoS, a QoS Negotiation Attribute Value Pair (AVP) and a QoS Upgrade AVP such that the QoS Negotiation AVP takes precedence over the QoS Upgrade AVP.

Description:
FIELD OF THE INVENTION 
     The invention is directed to packet switching communication networks, and in particular to authorizing Quality of Service (QoS) in 3GPP-compliant packet data networks. 
     BACKGROUND OF THE INVENTION 
     Long Term Evolution (LTE) is a new network scheme recommended by the 3rd Generation Partnership Project (3GPP). 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 Quality of Experience (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 23.203, 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. The 3GPP specification allows the Policy and Charging Control (PCC) architecture to interwork with older generation networks (e.g., General Packet Radio Service (GPRS)). 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 new service requests, creating new PCC rules commensurate with such requests, and providing these new PCC rules to a Policy and Charging Enforcement Function (PCEF) for installation. The 3GPP standards also define the format of service request messages and PCC rules. 
     The 3rd Generation Partnership Project (3GPP) Policy and Charging Control specifications provide a framework for authorizing Quality of Service (QoS) by Policy and Charging Rules Function (PCRF). These specifications provide QoS Negotiation and QoS Upgrade Attribute Value Pairs (AVPs) for negotiating and upgrading the QoS for General Packet Radio Service (GPRS) networks. The 3GPP specification suggests that the absence of QoS Negotiation AVP in the CCR indicates QoS negotiation supported and the absence of QoS Upgrade AVP in the CCR indicates QoS upgrade not supported. The 3GPP specifications are not complete and leave up to the reader the interpretation for implementation. For example, 3GPP specification does not specify if the QoS Negotiation and QoS Upgrade AVPs work in tandem or independently. 
     Therefore, a means of providing a deterministic way of calculating the authorized QoS is highly desirable. 
     SUMMARY OF THE INVENTION 
     Embodiments of the present invention provide a deterministic way of calculating the authorized QoS using various data points available at the PCRF (e.g., Requested QoS, User&#39;s subscription, Current bandwidth usage, etc. over on top of 3GPP specified QoS Negotiation AVP and QoS Upgrade AVP), such that QoS Negotiation AVP takes precedence over said QoS Upgrade AVP. 
     One aspect of the present invention is directed to a method for authorizing Quality of Service (QoS). The method comprises steps of: receiving a service request for a subscriber, the service request comprising a requested QoS, a QoS Negotiation Attribute Value Pair (AVP) and a QoS Upgrade AVP; retrieving from a Subscription Profile Repository (SPR), a QoS limit for the subscriber; and calculating an authorized QoS for the service request, wherein the QoS Negotiation AVP takes precedence over the QoS Upgrade AVP. 
     In some embodiments of the invention the step of calculating an authorized QoS further comprises steps of: determining if the requested bandwidth is greater than available bandwidth for the subscriber, defined as the QoS limit minus currently-used bandwidth for the subscriber; and if so, setting the authorized QoS for the service request to the available bandwidth for the subscriber if the QoS Negotiation AVP is set to QoS negotiation supported; otherwise rejecting the service request. 
     In some embodiments of the invention the requested bandwidth is not greater than the available bandwidth for the subscriber, then setting the authorized QoS to the available bandwidth for the subscriber only if the QoS Negotiation AVP is set to QoS negotiation supported and if the QoS Upgrade AVP is set to QoS Upgrade supported; otherwise setting the authorized QoS to the requested QoS. 
     In some embodiments of the invention the currently-used bandwidth for the subscriber comprises currently-used bandwidth for active PCC and/or QoS rules within an IP-CAN session of the subscriber. 
     In some embodiments of the invention the authorized QoS is communicated to a Policy and Charging Enforcement Function (PCEF). 
     Some embodiments of the invention further comprise a step of sending a Credit Control Answer (CCA) message in response to the service request. 
     In some embodiments of the invention the service request for a subscriber is received in the form of a Credit Control Request (CCR) message. 
     In some embodiments of the invention the method is performed at a Policy and Charging Rules Function (PCRF) node. 
     In some embodiments of the invention the PCRF node is a node or nodes providing PCRF functionality. 
     In some embodiments of the invention the PCRF node comprises an element in a 3GPP-compliant packet data network. 
     In some embodiments of the invention the 3GPP-compliant packet data network comprises a Long Term Evolution (LTE) or General Packet Radio Service (GPRS) network. 
     In some embodiments of the invention in which a specific Radio Access Type (RAT) with explicit upper bandwidth limit is used, the method further comprises a step of ensuring that the authorized QoS does not exceed a RAT-based upper limit. 
     Another aspect of the present invention is directed to a Policy and Charging Rules Function (PCRF) Node for a 3GPP-compliant packet data network the PCRF node configured to: receive a service request for a subscriber, the service request comprising a requested QoS, a QoS Negotiation Attribute Value Pair (AVP) and a QoS Upgrade AVP; retrieve from a Subscription Profile Repository (SPR), a QoS limit for the subscriber; and; calculate an authorized QoS for the service request; wherein the QoS Negotiation AVP takes precedence over the QoS Upgrade AVP. 
     Another aspect of the present invention is directed to a machine-readable storage medium encoded with instructions for a policy and rules charging function (PCRN) node, the machine-readable storage medium comprising: instructions for receiving a service request for a subscriber, the service request comprising a requested QoS (within the QoS Information AVP), a QoS Negotiation Attribute Value Pair (AVP) and a QoS Upgrade AVP; instructions for retrieving from a Subscription Profile Repository (SPR), a QoS limit for the subscriber; and instructions for calculating an authorized QoS for the service request, wherein the QoS Negotiation AVP takes precedence over the QoS Upgrade AVP. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Some embodiments of apparatus and/or methods in accordance with embodiments of the present invention are now described, by way of example only, and with reference to the accompanying drawings in which: 
         FIG. 1  illustrates a simplified block diagram of an LTE system; 
         FIG. 2  illustrates a table  200  describing the Authorized QoS  210  assigned according to an embodiment of the present invention; 
         FIG. 3  illustrates a table  300  with specific examples of inputs and the corresponding outputs of an embodiment of the present invention; and 
         FIG. 4  illustrates a flowchart of a method of an embodiment of the present invention. 
     
    
    
     In the figures like features are denoted by like reference characters. 
     DETAILED DESCRIPTION 
     In 3GPP-compliant networks, data plane traffic is carried over virtual connections called service data flows (SDFs), which are, in turn, carried over IP-CAN bearers—virtual containers with unique QoS characteristics. Multiple SDFs can be carried per IP-CAN bearer. SDFs are also referred to as service flows or IP service flows. Each user equipment (UE) (e.g., a smart phone), requires a connection to the network. This connection to the network is represented as an IP-CAN session. Each IP-CAN session can carry one or more IP-CAN bearers. 
       FIG. 1  illustrates a simplified block diagram of an LTE system  100 . User Equipment  102  communicates with a PCEF function  104 , which can be part of a Packet Data Network-Gateway (PDN-GW) (also referred to as a packet gateway (PGW) node), to initiate a request for service. The PCEF generates a Credit Control Request (CCR) message, such as CCR  105 , requesting an appropriate allocation of resources and forwards the request to PCRF node  106 . The CCR message to PCRF node  106  includes an EPS-Default-Bearer-QoS Attribute Value Pair (AVP) or QoS Information AVP containing the requested QoS by the subscriber. PCRF validates the message (its syntax, semantics) and then retrieves subscriber data from Subscription Profile Repository (SPR)  108 , to determine if the subscriber is valid, and the subscriber&#39;s QCI limit for the QCI specified in the request. Generally, the SPR  108  may store the following information, but not limited to, per subscriber, for non-Guaranteed Bit-Rate (non-GBR) calls: Aggregate Maximum Bit Rate (AMBR); the bandwidth limits for each non-GBR QCI; the bandwidth limits for a given application such as voice calls, Voice Over IP (VoIP) calls, or for specific applications such as, for example, Skype or Google Talk. The SPR  108  may be a device that stores information related to subscribers to the network  100 . Thus, SPR  108  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  108  may be a component of PCRF node  106  or may constitute an independent node within network  100 . Data stored by SPR  108  may include an identifier of each subscriber and indications of subscription information for each subscriber such as bandwidth limits, charging parameters, subscriber priority, and subscriber service preferences. 
     Based on the event type (e.g., IP-CAN Session establishment, AF Session modification, etc.), the PCRF node  106  returns a Credit Control Answer (CCA) or Re-Authorization Request (RAR) message  109  to the PCEF  104  with the subscriber&#39;s QCI limit and authorization to establish or modify a service. 
     The 3GPP specifications suggest that the PCRF may provide the authorized QoS at the Internet Protocol Connectivity Access Network (IP-CAN) bearer level, at the QoS Class Identifier (QCI) level and the service flow level. 
     The QoS Negotiation AVP indicates if the PCRF can return the authorized QoS that is different from the requested QoS (i.e., user is willing to negotiate the QoS). The QoS Upgrade AVP indicates if the PCRF can return the authorized QoS that is higher than the requested QoS (i.e., user is willing to upgrade the QoS). 
       FIG. 2  illustrates a table  200  describing the Authorized QoS  210  assigned by the PCRF  106  according to an embodiment of the present invention, for various input scenarios for Requested QoS  202 , QoS specified by the SPR (also referred to in this document as “SPR QoS”  204 ) for the specified QCI, QoS Negotiation AVP  206 , QoS Upgrade AVP  208 . The requested QoS  202  is also referred to as requested bandwidth  306  as shown in the table of  FIG. 3  and is specified in megabits per second (Mbps). It is included in the CCR message  105  from PCEF  104 . The SPR QoS is also referred to as Maximum allowed bandwidth  302  in  FIG. 3 . The QoS Negotiation AVP  206  (also shown as  308  in  FIG. 3 ) and QoS Upgrade AVP  208  (also shown as  310  in  FIG. 3 ) are included in the CCR message  105  from PCEF  104 . The Authorized QoS  210  is also referred to as authorized bandwidth  312  as shown in  FIG. 3  and is determined by the PCRF  106  and is incorporated in the CCA message built by the PCRF  106  to be sent to the PCEF  104  in the CCA answer message  109 . 
     In embodiments of the present invention, if QoS negotiation is not supported, this means that the requested bandwidth should either be authorized or rejected. 
     If the requested QoS  202  (x+n Mbps) is greater than the SPR QoS  204  (x Mbps) as shown in rows  212 ,  214 ,  216 ,  218  of table  200  in  FIG. 2 , then QoS Negotiation is the deciding attribute and QoS Upgrade does not matter (i.e., no influence on the PCRF QoS authorization). If QoS negotiation is supported, then the authorized QoS is set to the SPR QoS (x Mbps). If QoS negotiation is not supported, then the authorized QoS is shown as “Rejected” in  FIG. 2  which implies that the PCRF will reject the service request using a CCA message  109  to PCEF  104 . 
     In cases where the requested QoS  202  (x−n Mbps) is less than the SPR QoS  204  (x Mbps) as shown in the rows  220 ,  222 ,  224 ,  226  of table  200  in  FIG. 2 , upgrading the QoS above that which was requested is only permitted if QoS Negotiation is also supported. Thus if both QoS Negotiation is supported and QoS Upgrade is supported, then QoS can be upgraded and the authorized QoS  210  is set to the SPR QoS  204  (x Mbps), otherwise the authorized QoS  210  is set to the Requested QoS  202  (x−n Mbps). 
     Note that the subscriber&#39;s current bandwidth used is not discussed in  FIG. 2  but is also a parameter that the PCRF  106  takes into account when determining the Authorized QoS  210 . It will be discussed in more detail with reference to  FIG. 3 . For the purposes of understanding the table in  FIG. 2 , the subscriber&#39;s current bandwidth used may be assumed to be zero. 
     To further illustrate aspects of an embodiment of the invention, referring to  FIG. 3 , table  300  provides specific examples of inputs and the corresponding outputs of an embodiment of the present invention. In the example of table  300 , the subscriber bandwidth limit in SPR  302  as determined by QoS limit assigned to the subscriber in SPR  108  is set to 10 Mbps. The bandwidth currently in use  304  by the subscriber is set to 7 Mbps. The requested bandwidth  306  is set to 5 Mbps in rows  314 ,  316 ,  318 ,  320  of table  300 . Thus the requested bandwidth plus the bandwidth already in-use by the subscriber exceeds the maximum allowed bandwidth and QoS negotiation is necessary to allow the service request. QoS Negotiation  308  is the determining factor and if it is supported, the authorized bandwidth  312  is determined by subtracting the currently in-use bandwidth  304  from the maximum allowed bandwidth  302  to determine the available bandwidth which in the case of the first four rows of table  300  is 3 Mbps. Thus in rows  314 ,  316  of table  300 , the authorized bandwidth  312  is set to 3 Mbps which is included in the CCA answer message to be sent to the PCEF  104 . If QoS Negotiation  308  is not supported, then the service request is rejected as indicated by answer message  312  set to “rejected” in rows  318 ,  320  of table  300 . 
     In rows  322 ,  324 ,  326 ,  328  of table  300 , the requested bandwidth  306  is set to 2 Mbps; thus the requested bandwidth  306  (5 Mbps) plus the bandwidth already in-use  304  (7 Mbps) by the subscriber is less than the maximum allowed bandwidth  302  (10 Mbps). Upgrading the QoS above that which was requested is only permitted if QoS Negotiation is also supported. Thus if both QoS Negotiation is supported and QoS Upgrade is supported, as is the case for row  326  of table  300  then QoS can be upgraded from the request 2 Mbps to the 3 Mbps that is available (10 Mbps allowed minus 7 Mbps in-use), and the authorized bandwidth  312  to be included in the CCA answer  109  message is set to 3 Mbps. 
       FIG. 4  illustrates a flowchart of a method  400  of an embodiment of the present invention. The process starts at step  402 . At step  404 , the PCRF  106  receives a CCR message  105 , representing a service request for a UE  102 , from PCEF  104 . The request for service could originate from the UE  102  or from the AF  110 . The CCR  105  message contains a QoS Information AVP which includes QCI, MBR for upload and download, GBR for upload and download, QoS Negotiation AVP, QoS Upgrade AVP. At step  406 , the PCRF  106  extracts subscriber data from the SPR  108 , including the QoS limit for the QCI from the SPR and the requested QoS from the CCR message  105 . 
     At step  408 , the PCRF  106  determines if the requested QoS plus the bandwidth already in-use by the subscriber is greater than the QoS limit retrieved from the SPR  108  and if so, the process continues to step  410 . 
     At step  410 , the PCRF  106  determines if the QoS Negotiation AVP is set. Note that the QoS negotiation AVP takes precedence over the QoS Upgrade AVP, therefore the QoS Upgrade AVP has no effect on the decision at this branch of the process. If the QoS Negotiation AVP is set to QoS negotiation supported, the process proceeds to step  412  where the PCRF  106  calculates the Authorized QoS and sets the Authorized QoS for the service request to available bandwidth for the subscriber which is determined as the QoS limit specified in the SPR  108 , minus the bandwidth already in-use by the subscriber. The PCRF  106  sends CCA message to the PCEF  104 , specifying the Authorized QoS. The process then ends at step  414 . 
     Note that certain Radio Access Type (RAT) types can have an explicit upper bandwidth limit. For example, in GSM EDGE Radio Access Networks (GERAN)), the most a GERAN IP-CAN bearer can carry is 473.6 Kbps. In such cases, the PCRF also ensures that the authorized QoS does not exceed the RAT based upper limit. 
     If at step  410 , the PCRF  106  determines that the QoS Negotiation AVP is not set, then the PCRF  106  sends CCA message  109  to the PCEF  104 , rejecting the service request (received as CCR message  105 ). The process then ends at step  414 . 
     If at step  408 , the PCRF  106  determines that the requested QoS plus the bandwidth already in-use by the subscriber is not greater than the QoS limit retrieved from the SPR  108 , the process proceeds to step  418  where the PCRF  106  determines if the QoS Negotiation AVP is set to QoS negotiation supported and if so, the process proceeds to step  420 . 
     At step  420 , the PCRF  106  determines if the QoS Upgrade AVP is set to QoS upgrade supported and if so, the requested QoS can be upgraded from the requested QoS to the QoS limit. The process therefore proceeds to step  412  described above. 
     If at step  420 , the PCRF  106  determines that the QoS Upgrade AVP is set to QoS upgrade not supported, then the process proceeds to step  422 , where the PCRF  106  sets the Authorized QoS to the QoS requested from the CCR message  105 . The PCRF  106  sends CCA message  109  to PCEF  104 , specifying the Authorized QoS. The process then ends at step  414 . 
     If at step  418 , the PCRF  106  determines that the QoS Negotiation AVP is set to no QoS negotiation, then the process also proceeds to step  422  described above. 
     A person of skill in the art would readily recognize that steps of various above-described methods can be performed by programmed computers. Herein, some embodiments are also intended to cover program storage devices, e.g., digital data storage media, which are machine or computer-readable and encode machine-executable or computer-executable programs of instructions, wherein said instructions perform some or all of the steps of said above-described methods. The program storage devices may be, e.g., digital memories, magnetic storage media such as a magnetic disks and magnetic tapes, hard drives, or optically readable digital data storage media. The embodiments are also intended to cover computers programmed to perform said steps of the above-described methods. 
     The description and drawings merely illustrate the principles of the invention. It will thus be appreciated that those skilled in the art will be able to devise various arrangements that, although not explicitly described or shown herein, embody the principles of the invention and are included within its spirit and scope. Furthermore, all examples recited herein are principally intended expressly to be only for pedagogical purposes to aid the reader in understanding the principles of the invention and the concepts contributed by the inventor(s) to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions. Moreover, all statements herein reciting principles, aspects, and embodiments of the invention, as well as specific examples thereof, are intended to encompass equivalents thereof. 
     The functions of the various elements shown in the Figures, including any functional blocks labeled as “processors”, may be provided through the use of dedicated hardware as well as hardware capable of executing software in association with appropriate software. When provided by a processor, the functions may be provided by a single dedicated processor, by a single shared processor, or by a plurality of individual processors, some of which may be shared. Moreover, explicit use of the term “processor” or “controller” should not be construed to refer exclusively to hardware capable of executing software, and may implicitly include, without limitation, digital signal processor (DSP) hardware, network processor, application specific integrated circuit (ASIC), field programmable gate array (FPGA), read only memory (ROM) for storing software, random access memory (RAM), and non volatile storage. Other hardware, conventional and/or custom, may also be included. Similarly, any switches shown in the FIGS. are conceptual only. Their function may be carried out through the operation of program logic, through dedicated logic, through the interaction of program control and dedicated logic, or even manually, the particular technique being selectable by the implementer as more specifically understood from the context. 
     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 computer readable medium and so executed by a computer or processor, whether or not such computer or processor is explicitly shown. 
     Numerous modifications, variations and adaptations may be made to the embodiment of the invention described above without departing from the scope of the invention, which is defined in the claims.