Patent Publication Number: US-2023156829-A1

Title: Service-based policy for cellular communications

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     The is a continuation application of U.S. patent application Ser. No. 16/788,921, filed on Feb. 12, 2020, whose disclosure is incorporated by reference in its entirety herein. 
    
    
     BACKGROUND 
     The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure. 
     3GPP architectures specify that a policy for a session is selected based on the connection point, that is, the Access Point Name (APN) for 4G or the Data Network Name (DNN) for 5G. These architectures specify that the same policy applies for all packet data sessions via that connection point. 
     SUMMARY 
     A service-based policy architecture allows multiple policies to be applied to different services accessing the same APN/DNN. A gateway may inspect packets for content indicating the service and direct the session to different policy charging and rule functions (PCRFs) so that each service may be handled separately. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The figures depict a preferred embodiment for purposes of illustration only. One skilled in the art may readily recognize from the following discussion that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles described herein. 
         FIG.  1    is an simplified and exemplary block diagram of a 4G cellular communication system in accordance with the current disclosure; 
         FIG.  2    is an simplified and exemplary block diagram of a 5G cellular communication system in accordance with the current disclosure; 
         FIG.  3    is a block diagram of an exemplary system management function in accordance with the current disclosure; 
         FIG.  4    is a block diagram of an exemplary policy control function in accordance with the current disclosure; and 
         FIG.  5    is a flowchart of a method implementing a service-based policy for cellular communications. 
     
    
    
     DETAILED DESCRIPTION 
     As a mobile device can (and usually does have) have several IP addresses (or IPv6 prefixes) at once, for example, one for Internet access and one for operator services such as voice over LTE (VoLTE), each is bound to a different virtual network interface on the device. In this case, several protocol data unit (PDU) sessions are established simultaneously. Each is identified with a (human readable) name which in 2G, 3G and 4G networks was referred to as the APN (Access Point Name). In the 5G core, it is referred to as the DNN (Data Network Name). 
     Each session is how controlled by a set of policies according to the APN/DNN. For example, the subscriber may be charged based on use of a high volume application or have volume limits applied during peak usage hours. However, only one set of policies may be applied to each session according to the policy and charging rules function (PCRF) associated with the APN/DNN. 
     A system in accordance with the current disclosure performs a deep packet inspection on protocol data units (PDUs) to determine a service with which the PDU is associated. The PCRF and therefore the policy for a particular packet session associated with those PDU&#39;s is then selected based on the service rather than the APN/DNN for that session. 
     Turning to  FIG.  1   , a block diagram illustrates an exemplary embodiment of a system  100  in accordance with the current disclosure. The system  100  may include a plurality of subscriber devices  102 ,  104  in communication with a radio access network (RAN)  120  including cell sites  106 ,  108 ,  110  and other infrastructure equipment not depicted in  FIG.  1   . 
     Managing communication between subscriber devices and between a subscriber device and an external data entity (the outside world)  142 , is a core network  122 , called in a 4G LTE example, the evolved packet core (EPC). The core network  122  illustrated here is greatly simplified for the sake of clarity. A serving gateway  124  may act as a router between cell sites  106 ,  108 ,  110  and the rest of traffic-oriented components. Mobility management entities (MMEs)  126 ,  128  manage signaling to the base stations including call set up and handoffs. A home subscriber server (HSS)  130  may be a central database that contains information about all the subscribers to the operator&#39;s communication system  100 . In older communication system configurations the role of the HSS was performed by a home location registry (HLR). The HSS  130  may provide other system components with subscriber operational information. The functions and data associated with a prior art HSS may be found in several standards documents such as 3GPP TS 22.041. A dynamic subscriber profile service (DSS)  132  manages subscriber profiles. In some embodiments, the DSS  132  may be embodied within the HSS  130 . In other embodiments, an equipment identity register (EIR) may be incorporated in the DSS  132  for device whitelisting and blacklisting among other functions. A session management function-packet data network gateway control (packet data gateway, or P-GW)  134   a  may handle communication between subscriber devices  102 ,  104  and the outside world or endpoint, the digital entity  142   a . The digital entity  142   a  may be coupled to the core network via access point  138   a.    
     Policy servers  136   a  and  137   a , known separately in the 4G example as a policy control and charging rules function (PCRF) are responsible for control decision-making and flow-based charging. In an embodiment, the policy server  136   a  may instruct the P-GW  132  to enforce the PCRF&#39;s decisions via a policy control enforcement function (not depicted in  FIG.  1   ) which may reside in the P-GW  132   a . In a prior art embodiment, the selection of a policy server would be made by the P-GW  132  based on the APN being accessed, in this example, the APN  138   a . As described herein, the P-GW  132   a  may select from multiple PCRFs  136   a ,  137   a  based on the service associated with a data communication, described in more detail below. 
       FIG.  2    illustrates a cellular communication network  200  supporting 5G communications. Reference numbers from  FIG.  1    are reused for corresponding roles/functions in  FIG.  2   . A subscriber device  102   b  may be connected to the network via a radio access network  120   b . In this example, the subscriber device  102   b  may also be connected to an Access and Mobility Management Function (AMF)  160 . A session management function (SMF)  134   b . The SMF  134   b  is responsible for checking whether requests from the subscriber device  102   b  are compliant with the user&#39;s subscription including session types and quality of service (QoS) limits using policies stored in a first policy control function  136   b  and a second policy control function  137   b . That is, the SMF  134   b  selects a PCF that is used for policy identification and enforcement. The user plane function (UPF)  138   b  provides the interface to the outside world, illustrated as digital entity  142   b . As above, in the prior art implementation, the SMF  134   b  selects a PCF  136   b  or  137   b  based on the data network name (DNN) to which a particular data session is connected. In the network  200  in accordance with the current disclosure, the SMF  134   b  may select a PCF based on the service associated with the data session, not its DNN. The selection of more than one PCF  136   b  or  137   b  allows policy settings, such as service levels, to be tailored by application/service rather than by a data connection&#39;s access point. 
     Two elements of the networks  100  and  200  support the service-based selection of policy control functions.  FIG.  3    illustrates an exemplary session management function  134 . The SMF  134  may include a network interface  180  coupled to a processor  182 . The processor  182  may be connected to a services database  186  that stores information about the various services supported by the networks  100  and  200 . These services may include, but are not limited to, voice over LTE (VOLTE), rich communication services (RCS), support for various Internet of Things (IoT) devices, or services that allow the use of one phone number across multiple devices such as T-Mobile&#39;s DIGITs service. 
     For example, a system in accordance with the current disclosure allows one PCRF/PCF to be selected for a Voice over LTE (VOLTE) service while a different PCRF/PCF to be selected for a Rich Communication Service (RCS) for communications from the same subscriber device  102 . In another embodiment, a subscriber device supporting separate 4G and 5G sessions using different IP Media Subsystems (IMS) may be directed to separate PCRFs  136   a ,  137   a ,  136   b ,  137   b.    
     An exemplary session management function (SMF)  134   a ,  134   b  is illustrated in  FIG.  3   . The SMF  134   a ,  134   b  may include a processor  180  coupled to a network interface  182  used to communicate with other components of the system  100 ,  200 . A services database  184  may hold a list of services supported by the system  100 ,  200 , such as VOLTE and video over LTE (VILTE). A deep packet inspection module  186  may inspect packets to determine not only their origin and destination but the type of service with which the packet&#39;s session is associated. The deep packet inspection module  186  may reference the services database  184  to match data found in packets to supported services. A policy enforcement function  188  of the SMF  134   a ,  134   b  may enforce policies selected via the PCRF  136   a ,  137   a ,  136   b ,  137   b  as well as its own policies related, for example, to QoS. 
       FIG.  4    illustrates an exemplary PCF/PCRF  136 . The PCF/PCRF  136  may include a processor  190  coupled to a network interface  192  used to communicate with other system elements. The PCF/PCRF  136  may also include a unified policy framework (UPF)  194 , and for 5G systems, a control plane function policy  195 . Another component of the PCF/PCRF  136  may be a unified data repository (UDR)  196  that may be used to store, among other things, packet flow descriptions for application detection and subscription data. 
     A policy-per-service repository  198  may store policies such as data limits, QoS settings, and pricing related to specific services. In accordance with the current disclosure, these policies may differ between PCRF&#39;s, such as PCRC  136   a  and  137   a  or PCF  136   b  and  137   b . The ability to direct policy requests related to a data session&#39;s service is supported, in part, by the service-based policy repository  198 . 
     A method  200  of implementing a service-based policy for cellular communications is illustrated in the flowchart of  FIG.  5   . At block  202 , a data packet may be received at an SMF/P-GW  134 , the data packet being associated with a data communication session, for example, a voice call or an internet query. In an embodiment, the packet may not include actual user data but may be associated with the setup of the data communication session between endpoints. The SMF/P-GW  134  may inspect not only the packet header but may inspect the contents of the packet (deep packet inspection) to determine a service associated with the data communication session. The service may be compared at block  206  to a list of services, for example, stored in a services database  184  to determine if a special PCF/PCRF should be invoked. If not, a default PCF/PCRF, for example, PCRF  136   a  or PCF  136   b  may be selected based on the data session&#39;s APN/DNN, as done in the prior art. The default PCF/PCRF  136   a ,  136   b , at block  210 , may identify the appropriate policy or policies according to the service information passed from the SMF/P-GW  134 . Other system elements, including the SMF/P-GW  134  may manage the data session using the selected policies at block  216 . As discussed above, these policies may apply to allowable use, data limits, bandwidth restrictions, and more. 
     Returning to block  206 , when the service identified does not use the default setting, the ‘no’ branch may be taken to block  212  where a different PCF/PCRF, such as PCF  137   b , may be selected and a message may be sent to the selected PCF/PCRF. At block  214 , a policy or policies appropriate to the identified service may be selected and used, at block  216  to manage the data session. 
     At least one technical effect is the ability to expand the capability of 4G and 5G systems to increase the system flexibility related to policies managing different types of data sessions according to the service associated with that data session. 
     The current system and method benefit both users and system providers by allowing more flexibility in managing data sessions including bandwidth, data limits, and tariffs associated with different data sessions between the same subscriber device via the same APN/DNN. 
     The figures depict preferred embodiments for purposes of illustration only. One skilled in the art will readily recognize from the following discussion that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles described herein. 
     Upon reading this disclosure, those of skill in the art will appreciate still additional alternative structural and functional designs for the systems and methods described herein through the disclosed principles herein. Thus, while particular embodiments and applications have been illustrated and described, it is to be understood that the disclosed embodiments are not limited to the precise construction and components disclosed herein. Various modifications, changes and variations, which will be apparent to those skilled in the art, may be made in the arrangement, operation and details of the systems and methods disclosed herein without departing from the spirit and scope defined in any appended claims.