Error reports in network-interworking scenarios

Abstract

There is provided a method performed by a session management function for managing a network session of a user equipment (UE) in a network interworking scenario. The method comprises determining that the UE is accessing from and / or moved to a radio access network (RAN) and based at least on the determination, detecting an error related to a first policy and charging control (PCC) rule. The method further comprises, based at least on detecting the error related to the first PCC rule, transmitting, to a policy control function (PCF) (116), a first message which indicates the error related to the first PCC rule. The error related to the first PCC rule is that the first PCC rule could not be successfully installed and / or enforced because the RAN does not support dedicated bearers which are needed for installing and / or enforcing the first PCC rule.

Description

ERROR REPORTS IN NETWORK-INTERWORKING SCENARIOSTECHNICAL FIELD

[0001] This disclosure relates to error reports in network-interworking scenarios.BACKGROUND

[0002] Many mobile network operators (MNOs) that are deploying 5G System (5GS) plan to introduce 5GS roaming as a complement to Evolved Packet System (EPS) roaming. Regardless of whether the MNOs’ roaming partners have the EPS, 5GS, or both, all communication service providers (CSPs) will reasonably expect roaming services to continue to function without disruption. Annex B in the 3rd Generation Partnership Project (3GPP) Technical Specification (TS) 29.512 VI 8.4.0 defines procedures for 5G Core (5GC) and Evolved Packet Core (EPC) / Evolved Universal Terrestrial Radio Access Network (E-UTRAN) interworking.SUMMARY

[0003] In the 5GC and EPCZE-UTRAN interworking scenarios, SMF+PGW-C is enhanced to support a user equipment (UE) accessing a wireless network via Global System for Mobile communications (GSM) Enhanced Data rates for GSM Evolution (Edge) Radio Access Network (GERAN) / UTRAN over Gn / Gp interface. However, in the interworking scenarios, there may be a case where a policy and charging control (PCC) rule for a network session of the UE requires dedicated bearer(s) - i.e., requiring secondary PDP context or dedicated Quality of Service (QoS) flow. In such case, if the UE moves to the GERAN / UTRAN over Gn / Gp interface, i.e., the UE begins to access the network via the GERAN / UTRAN over the Gn / Gp interface, the PCC rule cannot be installed and / or enforced.

[0004] In such case, it may be desirable to inform a policy control function (PCF) that installation and / or enforcement of the PCC rule has been failed (“PCC rule failure”) for the reason that the UE’s current radio access network (RAN), e.g., the GERAN / UTRAN, does not support dedicated bearer(s).

[0005] However, in the existing art, there is no mechanism of informing the PCF that the cause of the PCC rule failure is that the UE’s current RAN does not support dedicated bearer(s).Furthermore, in the above case, there is no mechanism, in the existing art, for the PCF to inform an application function (AF) that the UE’s current RAN does not support dedicated bearer(s). Additionally, even after the UE moves back from, for example, the GERAN / UTRAN to E- UTRAN and then from the E-UTRAN to the NG-RAN network, in the existing art, there is no mechanism of informing the PCF and / or the AF that the UE’s current RAN now supports dedicated bearer(s).

[0006] Accordingly, in the embodiments of this disclosure, there is provided a method for reporting, to a PCF, a PCC rule failure with an indication (e.g., a failure code) indicating that the cause of the PCC rule failure is that the UE’s current RAN does not support dedicated bearer(s) and reporting, to an AF, a service allocation failure with an indication (e.g., a failure code) indicating that the cause of the service allocation failure is that the UE’s current RAN does not support dedicated bearer(s). The embodiments also provide a method of informing the PCF and / or the AF when the UE’s current RAN supports dedicated bearer(s) after the UE is moved from a RAN that does not support dedicated bearer(s) to a RAN that supports dedicated bearer(s).

[0007] More specifically, in one aspect of the embodiments of this disclosure, there is provided a method performed by a session management function (SMF+PGW-C) for managing a network session of a user equipment (UE) in a network interworking scenario. The method comprises determining that the UE is accessing from and / or moved to a radio access network (RAN) and, based at least on the determination, detecting an error related to a first policy and charging control (PCC) rule. The method further comprises, based at least on detecting the error related to the first PCC rule, transmitting, to a policy control function (PCF), a first message which indicates the error related to the first PCC rule, wherein the error related to the first PCC rule is that the first PCC rule could not be successfully installed and / or enforced because the RAN does not support dedicated bearers which are needed for installing and / or enforcing the first PCC rule.

[0008] In a different aspect, there is provided a method performed by a policy control function (PCF) for a network session of a user equipment (UE) in a network interworking scenario. The method comprises receiving, from a session management function (SMF+PGW-C), a first message which indicates an error related to a first policy and charging control (PCC) rule, wherein the error related to the first PCC rule is that the first PCC rule could not be successfully installed and / or enforced because a first RAN from which the UE is accessing and / or to which the UE ismoved does not support dedicated bearers which are needed for installing and / or enforcing the first PCC rule.

[0009] In a different aspect, there is provided a method performed by an application function (AF) for a network session of a user equipment (UE) in a network interworking scenario. The method comprises receiving, from a policy control function (PCF), a notification message indicating that dedicated bearers are not supported by a RAN from which the UE is accessing and / or to which the UE is moved and, based on receiving the notification message, determining a service that does not require dedicated bearers. The method further comprises transmitting, to the PCF, a response to the notification message, wherein the response to the notification information includes information about the determined service that does not require dedicated bearers.

[0010] In a different aspect, there is provided a computer program comprising instructions which when executed by processing circuitry cause the processing circuitry to perform the method of any one of the above embodiments.

[0011] In a different aspect, there is provided a carrier containing the computer program of the above embodiment, wherein the carrier is one of an electronic signal, an optical signal, a radio signal, and a computer readable storage medium.

[0012] In a different aspect, there is provided a session management function (SMF+PGW- C) for managing a network session of a user equipment (UE) in a network interworking scenario. The session management function is configured to determine that the UE is accessing from and / or moved to a radio access network (RAN); and based at least on the determination, detect an error related to a first policy and charging control (PCC) rule. The session management function is further configured to, based at least on detecting the error related to the first PCC rule, transmit, to a policy control function (PCF), a first message which indicates the error related to the first PCC rule, wherein the error related to the first PCC rule is that the first PCC rule could not be successfully installed and / or enforced because the RAN does not support dedicated bearers which are needed for installing and / or enforcing the first PCC rule.

[0013] In a different aspect, there is provided a policy control function (PCF) for a network session of a user equipment (UE) in a network interworking scenario. The PCF is configured to receive, from a session management function (SMF+PGW-C), a first message which indicates anerror related to a first policy and charging control (PCC) rule, wherein the error related to the first PCC rule is that the first PCC rule could not be successfully installed and / or enforced because a first RAN from which the UE is accessing and / or to which the UE is moved does not support dedicated bearers which are needed for installing and / or enforcing the first PCC rule.

[0014] In a different aspect, there is provided an application function (AF) for a network session of a user equipment (UE) in a network interworking scenario. The AF is configured to receive, from a policy control function (PCF), a notification message indicating that dedicated bearers are not supported by a RAN from which the UE is accessing and / or to which the UE is moved; and, based on receiving the notification message, determine a service that does not require dedicated bearers. The AF is further configured to transmit, to the PCF, a response to the notification message, wherein the response to the notification information includes information about the determined service that does not require dedicated bearers.

[0015] In a different aspect, there is provided an apparatus comprising processing circuitry; and a memory, said memory containing instructions executable by said processing circuitry, whereby the apparatus is operative to perform the method of any one of the above embodiments.

[0016] As explained above, the embodiments of this disclosure allow reporting a PCC rule failure to the PCF and a service allocation failure to the AF with an indication that the cause of the PCC rule failure or the service allocation failure is that the UE’s current RAN does not support dedicated bearer(s). In case no such indication is provided to the PCF or the AF, upon receiving the notification of the PCC rule failure or the service allocation failure, the PCF may re-provision the same PCC rule or another PCC rule requiring dedicated bearer(s), which will not be installed and / or enforced successfully. This re-provisioning of the same PCC rule or another PCC rule requiring dedicated bearer(s) would cause unnecessary signalling in the system. The embodiments of this disclosure prevent such unnecessary signalling in the system.

[0017] Furthermore, the embodiments of this disclosure allow, after the UE is moved from a RAN that does not support dedicated bearer(s) to a RAN that supports dedicated bearer(s), informing the PCF and / or the AF when the UE’s current RAN supports dedicated bearer(s) such that the PCF or the AF can re-provision a PCC rule which requires dedicated bearer(s).BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The accompanying drawings, which are incorporated herein and form part of the specification, illustrate various embodiments.

[0019] FIG. 1 shows a system according to some embodiments.

[0020] FIG. 2 shows a process according to some embodiments.

[0021] FIG. 3 shows a process according to some embodiments.

[0022] FIG. 4 shows a process according to some embodiments.

[0023] FIG. 5 shows a process according to some embodiments.

[0024] FIG. 6 shows a process according to some embodiments.

[0025] FIG. 7 shows a process according to some embodiments.

[0026] FIG. 8 shows a process according to some embodiments.

[0027] FIG. 9 shows an apparatus according to some embodiments.DETAILED DESCRIPTION

[0028] FIG. 1 shows a portion of a system 100 capable of handling 5GC and EPCZE- UTRAN interworking scenarios. Table 1 provided below lists abbreviations shown in FIG. 1. Table 1

[0029] In the system 100, elements 102 and 104 are for providing a 2G / 3G network, elements 106, 108, 112, and 126 are for providing a 4G network, and elements 122 and 124 are for providing a 5G network. In the system 100, same nodes may be used for serving different networks. For example, in the 4G network, the elements 118-120 may serve as, PGW-C, and PGW-U while, in the 5G network, the same elements may serve as SMF and UPF.

[0030] Note that, in the system 100, SGSN 104 may provide only Gn and Gp interfaces but not S3, S4, or S5 / S8 interfaces. Thus, in this disclosure, SGSN 104 may be referred to as “Gn / Gp SGSN.” On the contrary, SGSN 126 is configured to provide S3 and S4 interfaces. Thus, in this disclosure, SGSN 126 may be referred to as “S4-SGSN.” Furthermore, in this disclosure, GERAN / UTRAN 102 provided via the Gn / GP interfaces may be referred to as GERAN / UTRAN 102 over Gn / Gp interface and GERAN / UTRAN 102 provided via S4 interface may be referred to as GERAN / UTRAN 102 over S4 interface.

[0031] In the system 100, SMF+PGW-C 118 is enhanced to support a UE accessing the wireless network via the GERAN / UTRAN over Gn / Gp interface. Thus, in case a UE is served by the system 100, the UE may move between different networks - i.e., the 2G / 3G, 4G, and 5G networks - provided by the system 100. However, as the UE moves between the different networks, there may be scenarios where a PCC rule provisioned for the UE may not be installed and / or enforced due to the limitation of the UE’s current RAN. Three examples of such scenarios are provided below.

[0032] First Exemplary Scenario

[0033] In one scenario, after a packet data network (PDN) session with dedicated bearers is established for the UE by SMF+PGW-C 118 via the GERAN / UTRAN over S4 interface or via the E-UTRAN, a mobility procedure for the UE may be performed, thereby moving the UE to the GERAN / UTRAN over Gn / Gp interface, i.e., GERAN / UTRAN 102. In such scenario, thededicated bearers that were set up in SMF+PGW-C 118 may be released. However, since PCF 116 does not know the release of the dedicated bearers that were set up in SMF+PGW-C 118, it may provision, for a network session of the UE, a PCC rule that requires dedicated bearer(s). Additionally, since an application function (AF) does not know the release of the dedicated bearers, the AF may allocate a new service that requires dedicated bearer(s). In this case, the PCC rule cannot be installed and / or enforced successfully as the UE’s current RAN, i.e., GERAN / UTRAN over Gn / Gp interface 102, does not support dedicated bearer(s).

[0034] Second Exemplary Scenario

[0035] In another scenario, after a PDN session with or without dedicated bearers is established for the UE by SMF+PGW-C 118 via the GERAN / UTRAN over S4 interface or via the E-UTRAN, a mobility procedure for the UE may be performed, thereby moving the UE (1) from the 4G network, e.g., E-UTRAN 106, to the 5G network, i.e., NG-RAN 124, (2) from NG-RAN 124 back to E-UTRAN 106, and (3) from E-UTRAN 106 to GERAN / UTRAN over Gn / Gp interface 102. In this scenario, after the UE moves to NG-RAN 124, dedicated Quality of Service (QoS) flow may be set up. Then, after the UE moves back to E-UTRAN 106 and then to GERAN / UTRAN 102, the dedicated bearers that were set up in SMF+PGW-C 118 may be released. However, like the scenario described in the preceding paragraph, since PCF 116 does not know the release of the dedicated bearers that were set up in SMF+PGW-C 118, it may provision, for a network session of the UE, a PCC rule that requires dedicated bearer(s). Additionally, since an application function (AF) does not know the release of the dedicated bearers, the AF may allocate a new service that requires dedicated bearer(s). In this case, the PCC rule cannot be installed and / or enforced successfully as the UE’s current RAN, i.e., GERAN / UTRAN over Gn / Gp interface 102, does not support dedicated bearer(s).

[0036] Third Exemplary Scenario

[0037] In a different scenario, after a PDP context is established in GERAN / UTRAN over Gn / Gp interface 102, PCF 116 may provision a PCC rule requiring that SMF+PGW-C 118 initiates secondary PDP context activation. However, since GERAN / UTRAN over Gn / Gp interface 102 does not support secondary PDP context activation, the PCC rule cannot be installed and / or enforced.

[0038] In the existing art, there is a mechanism of reporting a Radio Access Technology (RAT) type from the SMF to the PCF and from the PCF to the AF. However, reporting the RATtype would not be sufficient to solve the problems described above. For example, in case the UE is accessing from S4-SGSN which supports secondary PDP context, the reported RAT type would be the GERAN / UTRAN. However, the PCF and / or the AF would not know whether the GERAN / UTRAN is provided via the S4-SGSN which supports secondary PDP context or via the Gn / Gp SGSN which does not support the secondary PDP context.

[0039] In order to solve the problems illustrated in the above three scenarios, in the embodiments of this disclosure, there is provided a process 200 shown in FIG. 2. The process 200 is applicable to a scenario where a PCC rule provisioned by PCF 116 requires dedicated bearer(s) but the UE’s current RAN does not support dedicated bearers.

[0040] Note that, in this disclosure, supporting dedicated bearer(s) may be equivalent to supporting dedicated QoS flow(s) and / or supporting secondary PDP context. Thus, in this disclosure, that the UE’s current RAN does not support dedicated bearer(s) may be same as that the UE’s current RAN does not support dedicated QoS flow(s) and / or that the UE’s current RAN does not support secondary PDP context. Similarly, in this disclosure, requiring dedicated bearer(s) may be same as requiring dedicated QoS flow(s) and / or requiring secondary PDP context.

[0041] The process 200 may begin with step s202. The step s202 comprises SMF+PGW- C 118 detecting that the UE is accessing from and / or moved to a RAN that does not support dedicated bearer(s). One example of the RAN that does not support dedicated bearer(s) is GERAN / UTRAN 102, i.e., the GERAN / UTRAN 102 over Gn / Gp interface. Then the process 200 may proceed to step s204.

[0042] The step s204 comprises SMF+PGW-C 118 determining that a PCC rule provisioned by PCF 116 for a network session of the UE requires dedicated bearer(s). Even though FIG. 2 shows that the step s204 is performed after the step s202, in some embodiments, the step s202 may be performed after the step s204 is performed.

[0043] Based on (1) detecting that the UE is accessing from and / or moved to a RAN that does not support dedicated bearer(s) and (2) determining that the PCC rule provisioned by PCF 116 for the network session of the UE requires dedicated bearer(s), in step s206, SMF+PGW-C 118 determines that the PCC rule cannot be installed and / or enforced, i.e., a PCC rule failure.

[0044] After determining that the PCC rule cannot be installed and / or enforced, in step s208, SMF+PGW-C 118 transmits to PCF 116 a message indicating that the PCC rule cannot beinstalled and / or enforced because the UE’s current RAN, e.g., GERAN / UTRAN over Gn / Gp interface 102, does not support dedicated bearer(s). More specifically, in some embodiments, the message indicating that the PCC rule cannot be installed and / or enforced may include an information element (IE) of which value indicates the cause of the PCC rule failure. This value may be referred to as “Enumeration FailureCode.” The table below shows an example of the failure code.Table 5.6.3.9-1: Enumeration FailureCode

[0045] As shown in the above table, in some embodiments, the value of the IE does not merely indicate that the UE’s current RAN does not support dedicated bearer(s). Rather, the value of the IE may indicate that the PCC rule cannot be installed and / or enforced because the UE is accessing from and / or moved to the GERAN / UTRAN over the Gn / Gp interface. In other words, in some embodiments, the value of the IE may be directed to the specific type of RAN - i.e., the GERAN / UTRAN over Gn / Gp interface such that, upon receiving this value, the PCF may determine that the UE’s current RAN is the GERAN / UTRAN over the Gn / Gp interface.

[0046] In some embodiments, the message transmitted in the step s208 may also include an IE identifying the type of a SGSN associated with the UE’ s current interface accessing the RAN (hereinafter, “current SGSN”). For example, in case the UE’s current RAN is GERAN / UTRAN 102, this IE may identify that the type of the current SGSN is Gn / Gp SGSN. In some embodiments, this IE may be included in another IE (“ServingNFIdentity”) which identifies an identify of a serving network function (NF). The table below shows IES included in the ServingNFIdentity IE.Table 5.6.2.38-1: Definition of type ServingNfldentity

[0047] Here, the IE “sgsnType” identifies the type of current SGSN. The value of the sgsnType IE may be defined as follows:Enumeration: SgsnTypeTable 5.6.3.XX-1: Enumeration SgsnType

[0048] As shown in the table above, the value of the sgsnType IE may indicate whether the serving SGSN type is a Gn SGSN or S4 SGSN.

[0049] In some embodiments, the transmission of the IE identifying the current SGSN may be determined based on the capability of SMF+PGW-C 118 and PCF 116. For example, SMF+PGW-C 118 may send this IE to PCF 116 only when PCF 116 supports decoding this IE. If PCF 116 does not support decoding this IE, SMF+PGW-C 118 may not send this IE to PCF 116.Alternatively, SMF+PGW-C 118 may send this IE to PCF 116 regardless of whether PCF 116 supports decoding it. In such case, if PCF 116 does not support decoding the IE, PCF 116 may simply ignore the IE.

[0050] After receiving the message indicating that the PCC rule cannot be installed and / or enforced because the UE’s current RAN does not support dedicated bearer(s), in step s210, PCF 116 may transmit to the AF a message indicating that a service provisioned by the AF cannot be allocated, i.e., a service allocation failure. Like the PCC rule failure message transmitted in the step s208, this service allocation failure message may indicate that the UE’s current RAN, e.g.,GERAN / UTRAN 102, does not support dedicated bearer(s). For example, in some embodiments, the service allocation failure message may include an information element (IE) of which value indicates the cause of the service allocation failure. The value of the IE may be defined as shown in the table provided below.Table 5.6.3.7-1: Enumeration AfEvent

[0051] As shown in the table above, the value of the IE may indicate whether the UE’s current RAN supports dedicated bearer(s). Note that, in some embodiments, the mere indication that the UE’s current RAN does not support dedicated bearer(s) may be sufficient for the AF to know that the UE’s current RAN is the GERAN / UTRAN over Gn / Gp interface.

[0052] After receiving the message indicating that the UE’s current RAN does not support dedicated bearer(s), in step s212, the AF may derive new service information that does not require dedicated bearer(s). Then, in step s214, the AF may transmit to PCF 116 a message indicating that the new service information. Upon receiving the message indicating the new service information, in step s216, PCF 116 may provision a new PCC rule that does not require dedicated bearer(s). After provisioning the new PCC rule, in step s218, PCF 116 may transmit to SMF+PGW-C 118 a message indicating the new PCC rule.

[0053] After the new PCC rule is installed and enforced, the UE may move back to a RAN that supports dedicated bearer(s). In such scenario, the process 200 may proceed to step s220. Step s220 comprises SMF+PGW-C 118 detecting that the UE is accessing from and / or moved to a RAN that supports dedicated bearer(s). For example, let’s assume that the UE is now accessing from and / or moved to the GERAN / UTRAN over S4 interface.

[0054] Then, in step s222, SMF+PGW-C 118 transmits to PCF 116 a message identifying the type of a SGSN (i.e. S4-SGSN) associated with the UE’s current RAN - i.e., the RAN that supports dedicated bearer(s). Then, in step s224, PCF+ 116 transmits to the AF a message indicating that the UE’s current RAN supports dedicated bearer(s).

[0055] After receiving the message indicating that the UE’s current RAN supportsdedicated bearer(s), in step s226, the AF may derive new service information that may require dedicated bearer(s). Then, in step s228, the AF may transmit to PCF 116 a message indicating that the new service information. Upon receiving the message indicating the new service information, in step s230, PCF 116 may provision a new PCC rule that may require dedicated bearer(s). After provisioning the new PCC rule, in step s232, PCF 116 may transmit to SMF+PGW-C 118 a message indicating the new PCC rule.

[0056] As explained above, in the process 200, in case the provisioned PCC rule cannot be installed and / or enforced for the reason that the UE’s current RAN does not support dedicated bearer(s), SMF+PGW-C 118 informs PCF 116 the specific cause of the PCC rule failure. By informing PCF 116 the specific cause of the PCC rule failure, PCF 116 may prevent itself from provisioning a new PCC rule that requires dedicated bearer(s) such that the new PCC rule can be installed and / or enforced successfully without further signaling.

[0057] Similarly, in the process 200, in case the provisioned service cannot be allocated for the reason that the UE’s current RAN does not support dedicated bearer(s), PCF 116 informs the AF the specific cause of the service allocation failure. By informing AF the specific cause of the service allocation failure, the AF may prevent itself from provisioning service information that requires dedicated bearer(s).

[0058] FIG. 3 shows a procedure defined in 3 GPP TS 29.513 VI 8.4.0, to which the process 200 is applied. The procedure is defined in 3GPP TS 29.513 at section 5.2.2.3. As explained in the cited section of the 3GPP TS, this procedure is performed when a PCC rule error is reported. Note that, for simple explanation purpose, not all messages involved in the procedure are shown in FIG. 3.

[0059] The procedure shown in FIG. 3 is tailored to a specific scenario. In the scenario, the UE was initially connected to the EPS, and thus a PDN connection with dedicated bearer(s) was created in the SMF+PGW-C. Then, the UE moved to the 5GS, and thus dedicated QoS flow was created. Then, the UE moved back to the EPS where dedicated bearer(s) is created. Finally, the UE moved to the GERAN / UTRAN over Gn / Gp interface.

[0060] In step 0a, the PCF is subscribed to an event of a location change with respect to a serving core network (CN) node. The subscription to this particular event is indicated by the enumeration value “SCNN_CH” which is defined in 3GPP TS 29.512 V18.4.0.

[0061] In step 0b, the AF is subscribed to an event of a change on the status of the UE’scurrent RAN as to whether the UE’s current RAN supports dedicated bearer(s) or not.

[0062] Because, in the step 0a, the PCF is subscribed to the event of a location change with respect to a serving CN node, after the UE moved to the GERAN / UTRAN over Gn / Gp interface, in step 1, the SMF+PGW-C transmits to the PCF an Npcf SMPolicyControl Update Request. This Request is an example of the message transmitted in the step s208.

[0063] Like the message transmitted in the step s208, the Npcf SMPolicyControl Update Request may indicate that a provisioned PCC rule was not installed and / or enforced successfully. In other words, the Npcf SMPolicyControl Update Request may indicate the PCC rule failure. Additionally, the Npcf SMPolicyControl Update Request may include an IE of which the value indicates the cause of the PCC rule failure. Thus, in FIG. 3, the value of the IE may indicate that the UE’s current RAN does not support dedicated bearers. Additionally, the value of the IE may indicate that dedicated bearers are not supported because the UE’s current RAN is the GERAN / UTRAN over Gn / Gp interface.

[0064] Also, like the message transmitted in the step s208, the Npcf_SMPolicyControl _Update Request may identify the type of a current serving network function (NF) (e.g., the type of the current SGSN). For example, in FIG. 3, the UE is currently connected to the GERAN / UTRAN via Gn / Gp, and thus the Npcf_SMPolicyControl_ Update Request may indicate that the type of the current serving NF is GN-SGSN.

[0065] After receiving the message, in step 2, the PCF transmits to the AF an Npcf PolicyAuthorization Notify Request. This Request is an example of the message transmitted in the step s210. The transmission of this Request is triggered based on the occurrence of an event for which the AF requested a notification. In FIG. 3, the event for which the AF requested a notification is that the UE’s current RAN no longer supports dedicated bearer(s).

[0066] After receiving the Npcf_PolicyAuthorization_Notify Request, in step 3, the AF transmits to the PCF an Npcf PolicyAuhtoirzation Update request which includes modified service information. This Request is an example of the message transmitted in the step s214.

[0067] Upon receiving the message, the PCF may provision a new PCC rule and, in step 4, the PCF may transmit to the SMF+PGW-C a Npcf SMPolicyControl Update Response including the new PCC rule. This Response is an example of the message transmitted in the step s218.

[0068] After the new PCC rule is installed and enforced, the UE moves to the S4-SGSNor the LTE. Then, in step 5a or 5b, the SMF+PGW-C transmits to the PCF an Npcf SMPolicyControl Update Request. This Request is an example of the message transmitted in the step s222.

[0069] Like the message transmitted in the step s222, the Npcf_SMPolicyControl_Update Request may identify the type of a current serving network function (NF) (e.g., the type of the current SGSN). For example, in FIG. 3, the UE is now connected to the S4-SGSN or the LTE, and thus the Npcf_SMPolicyControl_ Update Request may indicate that the type of the current serving NF is S4-SGSN / ANGwAddr. Note that, as explained above, this Request is transmitted to the PCF because, in the step 0a, the PCF is subscribed to the event of a location change with respect to a serving CN node.

[0070] After receiving the message, in step 6, the PCF transmits to the AF an Npcf PolicyAuthorization Notify Request. This Request is an example of the message transmitted in the step s224. The transmission of this Request is triggered based on the occurrence of an event for which the AF requested a notification. In FIG. 3, the event for which the AF requested a notification is that the UE’s current RAN now supports dedicated bearer(s).

[0071] After receiving the Npcf_PolicyAuthorization_Notify Request, in step 7, the AF transmits to the PCF an Npcf PolicyAuhtoirzation Update request which includes modified service information. This Request is an example of the message transmitted in the step s228.

[0072] Upon receiving the message, the PCF may provision a new PCC rule and, in step 8, the PCF may transmit to the SMF+PGW-C a Npcf SMPolicyControl Update Response including the new PCC rule. This Response is an example of the message transmitted in the step s232. Then, the new PCC rule is installed and enforced.

[0073] The procedure shown in FIG. 4 is identical to the procedure shown in FIG. 3 except for that the procedure shown in FIG. 4 is tailored to a different scenario. In the scenario corresponding to FIG. 4, the UE was initially connected to the EPS, and thus a PDN connection with dedicated bearer(s) was created in the SMF+PGW-C. Then, the UE moved to the GERAN / UTRAN. The steps of the procedure shown in FIG. 4 are identical to the steps of the procedure shown in FIG. 3, and thus explanation about the steps of the procedure shown in FIG. 4 are omitted.

[0074] FIG. 5 shows a procedure defined in 3GPP TS 29.513 VI 8.4.0, to which the process 200 is applied. The procedure is defined in 3GPP TS 29.513 at section 5.2.2.2. L Note that, forsimple explanation purpose, not all messages involved in the procedure are shown in FIG. 5.

[0075] The procedure shown in FIG. 5 is tailored to a specific scenario. In the scenario, the UE is connected to the GERAN / UTRAN over Gn / Gp interface, and primary PDP context is created in the SMF+PGW-C.

[0076] In step 0, the AF is subscribed to an event of a change on the status of the UE’s current RAN as to whether the UE’s current RAN supports dedicated bearer(s) or not.

[0077] In step 1 (either in case 1 or 2), the SMF+PGW-C receives from the PCF a message indicating a new PCC rule which requires secondary PDP context. As mentioned above, supporting / requiring secondary PDP context may be equivalent to supporting / requiring dedicated bearer(s) and / or supporting / requiring dedicated QoS flow.

[0078] After receiving the message, the SMF+PGW-C determines that the UE’s current RAN, e.g., the GERAN / UTRAN over Gn / Gp interface, does not support secondary PDP context. Thus, in step 2, the SMF+PGW-C transmits to the PCF a message indicating that the UE’s current RAN does not support secondary PDP context.

[0079] Upon receiving the message, the PCF may transmit to the AF a message indicating that the UE’s current RAN does not support secondary PDP context. Then, the AF may provision service information that does not require secondary PDP context and transmit to the PCF a message indicating the new service information. Then the PCF may provision a new PCC rule that does not require the secondary PDP context and transmit to the SMF+PGW-C a message indicating the new PCC rule. Then the new PCC rule may be installed and enforced.

[0080] FIG. 6 shows a process 600 performed by a session management function (SMF+PGW-C) (118) for managing a network session of a user equipment (UE) in a network interworking scenario according to some embodiments. The process 600 may begin with step s602. The step s602 comprises determining that the UE is accessing from and / or moved to a radio access network (RAN). Step s604 comprises, based at least on the determination, detecting an error related to a first policy and charging control (PCC) rule. Step s606 comprises, based at least on detecting the error related to the first PCC rule, transmitting, to a policy control function (PCF) (116), a first message which indicates the error related to the first PCC rule, wherein the error related to the first PCC rule is that the first PCC rule could not be successfully installed and / or enforced because the RAN does not support dedicated bearers which are needed for installing and / or enforcing the first PCC rule.

[0081] In some embodiments, the network interworking scenario is a 5G core (5GC) and evolved packet core (EPC) interworking scenario.

[0082] In some embodiments, the process 600 comprises detecting that the type of a current serving general packet radio service (GPRS) support node (SGSN) for handling the network session of the UE is Gn SGSN or Gp SGGN, and the first message transmitted to the PCF indicates that the type of the current SGSN for handling the network session of the UE is Gn SGSN or Gp SGGN.

[0083] In some embodiments, the process 600 further comprises, based at least on transmitting the first message to the PCF, receiving, from the PCF, a response to the first message, the response to the first message indicates a second PCC rule, and installing and / or enforcing the second PCC rule does not require dedicated bearers.

[0084] In some embodiments, the process 600 further comprises: detecting that the type of the current SGSN for handling the network session of the UE has been changed to S4-SGSN; and based at least on detecting that the type of the current SGSN has been changed to S4-SGSN, transmitting, to the PCF, a second message indicating that the type of the current SGSN for handling the network session of the UE is S4-SGSN.

[0085] In some embodiments, the process 600 further comprises, based at least on transmitting the second message to the PCF, receiving, from the PCF, a response to the second message, the response to the second message indicates a third PCC rule, and installing and / or enforcing the third PCC rule requires dedicated bearers.

[0086] In some embodiments, the process 600 further comprises: receiving, from the PCF, a notification message indicating the first PCC rule which requires a secondary packet data protocol (PDP) context activation; and based at least on determining that the UE is accessing from and / or moved to the RAN which does not support dedicated bearers, determining that the secondary PDP context activation required for the first PCC rule cannot be performed. The error related to the first PCC rule is detected based on the determination that the secondary PDP context activation required for the first PCC rule cannot be performed.

[0087] FIG. 7 shows a process 700 performed by a policy control function (PCF) (116) for a network session of a user equipment (UE) in a network interworking scenario according to some embodiments. The process 700 may begin with step s702. The step s702 comprises receiving, from a session management function (SMF+PGW-C) (118), a first message which indicates anerror related to a first policy and charging control (PCC) rule. The error related to the first PCC rule is that the first PCC rule could not be successfully installed and / or enforced because a first RAN from which the UE is accessing and / or to which the UE is moved does not support dedicated bearers which are needed for installing and / or enforcing the first PCC rule.

[0088] In some embodiments, the network interworking scenario is a 5G core (5GC) and evolved packet core (EPC) interworking scenario.

[0089] In some embodiments, the first message received from the session management function indicates that the type of a current serving general packet radio service (GPRS) support node (SGSN) for handling the network session of the UE is Gn SGSN or Gp SGGN.

[0090] In some embodiments, the process 700 further comprises based at least on receiving the first message, transmitting, to an application function, a notification message indicating that the use of a dedicated bearer is not supported by the first RAN from which the UE is accessing and / or to which the UE is moved.

[0091] In some embodiments, the process 700 further comprises based at least on transmitting the notification message to the application function, receiving, from the application function, a response to the notification message, wherein the response to the notification message including information about a service that does not require dedicated bearers.

[0092] In some embodiments, the process 700 further comprises, based at least on receiving the response to the notification message from the application function, transmitting, to the session management function, a response to the first message, the response to the first message indicates a second PCC rule, and installing and / or enforcing the second PCC rule does not require dedicated bearers.

[0093] In some embodiments, the process 700 further comprises receiving, from the session management function, a second message indicating that the type of the current SGSN for handling the network session of the UE is S4-SGSN, and the S4-SGSN is associated with a second RAN different from the first RAN, and the UE is moved from the first RAN to the second RAN and / or is accessing the second RAN.

[0094] In some embodiments, the process 700 further comprises based at least on receiving the second message, transmitting, to the application function, a notification message indicating that the use of a dedicated bearer is supported by the different RAN from which the UE is accessing and / or to which the UE is moved.

[0095] In some embodiments, the process 700 further comprises, based at least on receiving the second message to the session management entity, transmitting, to the policy management entity, a response to the second message. The response to the second message indicates a third PCC rule, and installing and / or enforcing the third PCC rule requires dedicated bearers.

[0096] In some embodiments, the process 700 further comprises transmitting, to the session management entity, a notification message indicating the first PCC rule which requires a secondary packet data protocol (PDP) context activation procedure. The error related to the first PCC rule is detected based on determining that the secondary PDP context activation procedure required for the first PCC rule cannot be initiated.

[0097] FIG. 8 shows a process 800 performed by an application function (AF) for a network session of a user equipment (UE) in a network interworking scenario according to some embodiments. The process 800 may begin with step s802. The step s802 comprises receiving, from a policy control function (PCF) (116), a notification message indicating that dedicated bearers are not supported by a RAN from which the UE is accessing and / or to which the UE is moved. Step s804 comprises, based on receiving the notification message, determining a service that does not require dedicated bearers. Step s806 comprises, transmitting, to the PCF, a response to the notification message, wherein the response to the notification information includes information about the determined service that does not require dedicated bearers.

[0098] In some embodiments, the network interworking scenario is a 5G core (5GC) and evolved packet core (EPC) interworking scenario.

[0099] In some embodiments, the process 800 further comprises receiving, from the PCF, another notification message indicating that dedicated bearers are supported by an updated RAN from which the UE is accessing and / or to which the UE is moved; based on receiving said another notification message, determining a service that requires dedicated bearers; and transmitting, to the PCF, a response to said another notification message, wherein the response to said another notification message includes information that requires dedicated bearers.

[0100] FIG. 9 is a block diagram of a network node 900 which may be used to implement any of the entities shown in FIG. 1, according to some embodiments. As shown in FIG. 9, networknode 900 may comprise: processing circuitry (PC) 902, which comprises one or more processors (P) 955 (e.g., one or more general purpose microprocessors and / or one or more other processors, such as an application specific integrated circuit (ASIC), field-programmable gate arrays (FPGAs), and the like), which processors may be co-located in a single housing or in a single data center or may be geographically distributed (e.g., network node 900 may be a distributed computing apparatus comprising two or more computers or a monolithic computing apparatus consisting of a single computer); at least one network interface 948 (e.g., a physical interface or air interface) comprising a transmitter (Tx) 945 and a receiver (Rx) 947 for enabling network node 900 to transmit data to and receive data from other nodes connected to network 110 (e.g., an Internet Protocol (IP) network) to which network interface 948 is connected (physically or wirelessly) (e.g., network interface 948 may be coupled to an antenna arrangement comprising one or more antennas for enabling network node 900 to wirelessly transmit / receive data); and a storage unit (a.k.a., “data storage system”) 908, which may include one or more non-volatile storage devices and / or one or more volatile storage devices. In embodiments where PC 902 includes a programmable processor, a computer readable storage medium (CRSM) 942 may be provided. CRSM 942 may store a computer program (CP) 943 comprising computer readable instructions (CRI) 944. CRSM 942 may be a non-transitory computer readable medium, such as, magnetic media (e.g., a hard disk), optical media, memory devices (e.g., random access memory, flash memory), and the like. In some embodiments, the CRI 944 of computer program 943 is configured such that when executed by PC 902, the CRI causes network node 900 to perform steps described herein (e.g., steps described herein with reference to the flow charts). In other embodiments, network node 900 may be configured to perform steps described herein without the need for code. That is, for example, PC 902 may consist merely of one or more ASICs. Hence, the features of the embodiments described herein may be implemented in hardware and / or software.

[0101] While various embodiments are described herein, it should be understood that they have been presented by way of example only, and not limitation. Thus, the breadth and scope of this disclosure should not be limited by any of the above-described exemplary embodiments. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the disclosure unless otherwise indicated herein or otherwise clearly contradicted by context.

[0102] As used herein transmitting a message “to” or “toward” an intended recipient encompasses transmitting the message directly to the intended recipient or transmitting the message indirectly to the intended recipient (i.e., one or more other nodes are used to relay the message from the source node to the intended recipient). Likewise, as used herein receiving a message “from” a sender encompasses receiving the message directly from the sender or indirectly from the sender (i.e., one or more nodes are used to relay the message from the sender to the receiving node). Further, as used herein “a” means “at least one” or “one or more.”

[0103] Additionally, while the processes described above and illustrated in the drawings are shown as a sequence of steps, this was done solely for the sake of illustration. Accordingly, it is contemplated that some steps may be added, some steps may be omitted, the order of the steps may be re-arranged, and some steps may be performed in parallel.

Claims

CLAIMS1. A method (600) performed by a session management function (SMF+PGW-C) (118) for managing a network session of a user equipment (UE) in a network interworking scenario, the method comprising: determining (s602) that the UE is accessing from and / or moved to a radio access network (RAN); based at least on the determination, detecting (s604) an error related to a first policy and charging control (PCC) rule; and based at least on detecting the error related to the first PCC rule, transmitting (s606), to a policy control function (PCF) (116), a first message which indicates the error related to the first PCC rule, wherein the error related to the first PCC rule is that the first PCC rule could not be successfully installed and / or enforced because the RAN does not support dedicated bearers which are needed for installing and / or enforcing the first PCC rule.

2. The method of claim 1, wherein the network interworking scenario is a 5G core (5GC) and evolved packet core (EPC) interworking scenario.

3. The method of claim 1 or 2, wherein the method comprises detecting that the type of a current serving general packet radio service (GPRS) support node (SGSN) for handling the network session of the UE is Gn SGSN or Gp SGGN, and the first message transmitted to the PCF indicates that the type of the current SGSN for handling the network session of the UE is Gn SGSN or Gp SGGN.

4. The method of any one of claims 1-3, wherein the method further comprises, based at least on transmitting the first message to the PCF, receiving, from the PCF, a response to the first message, the response to the first message indicates a second PCC rule, andinstalling and / or enforcing the second PCC rule does not require dedicated bearers.

5. The method of claim 3 or 4, wherein the method further comprises: detecting that the type of the current SGSN for handling the network session of the UE has been changed to S4-SGSN; and based at least on detecting that the type of the current SGSN has been changed to S4- SGSN, transmitting, to the PCF, a second message indicating that the type of the current SGSN for handling the network session of the UE is S4-SGSN.

6. The method of claim 5, wherein the method further comprises, based at least on transmitting the second message to the PCF, receiving, from the PCF, a response to the second message, the response to the second message indicates a third PCC rule, and installing and / or enforcing the third PCC rule requires dedicated bearers.

7. The method of any one of claims 1-6, wherein the method further comprises: receiving, from the PCF, a notification message indicating the first PCC rule which requires a secondary packet data protocol (PDP) context activation; and based at least on determining that the UE is accessing from and / or moved to the RAN which does not support dedicated bearers, determining that the secondary PDP context activation required for the first PCC rule cannot be performed, and the error related to the first PCC rule is detected based on the determination that the secondary PDP context activation required for the first PCC rule cannot be performed.

8. A method (700) performed by a policy control function (PCF) (116) for a network session of a user equipment (UE) in a network interworking scenario, the method comprising:receiving (s702), from a session management function (SMF+PGW-C) (118), a first message which indicates an error related to a first policy and charging control (PCC) rule, wherein the error related to the first PCC rule is that the first PCC rule could not be successfully installed and / or enforced because a first RAN from which the UE is accessing and / or to which the UE is moved does not support dedicated bearers which are needed for installing and / or enforcing the first PCC rule.

9. The method of claim 8, wherein the network interworking scenario is a 5G core (5GC) and evolved packet core (EPC) interworking scenario.

10. The method of claim 8 or 9, wherein the first message received from the session management function indicates that the type of a current serving general packet radio service (GPRS) support node (SGSN) for handling the network session of the UE is Gn SGSN or Gp SGGN.

11. The method of any one of claims 8-10, wherein the method further comprises: based at least on receiving the first message, transmitting, to an application function, a notification message indicating that the use of a dedicated bearer is not supported by the first RAN from which the UE is accessing and / or to which the UE is moved.

12. The method of claim 11, wherein the method further comprises: based at least on transmitting the notification message to the application function, receiving, from the application function, a response to the notification message, wherein the response to the notification message including information about a service that does not require dedicated bearers.

13. The method of claim 12, wherein the method further comprises, based at least on receiving the response to the notification message from the application function, transmitting, to the session management function, a response to the first message,the response to the first message indicates a second PCC rule, and installing and / or enforcing the second PCC rule does not require dedicated bearers.

14. The method of any one of claims 8-13, wherein the method further comprises receiving, from the session management function, a second message indicating that the type of the current SGSN for handling the network session of the UE is S4-SGSN, and the S4-SGSN is associated with a second RAN different from the first RAN, and the UE is moved from the first RAN to the second RAN and / or is accessing the second RAN.

15. The method of claim 14, wherein the method further comprises: based at least on receiving the second message, transmitting, to the application function, a notification message indicating that the use of a dedicated bearer is supported by the different RAN from which the UE is accessing and / or to which the UE is moved.

16. The method of claim 15, wherein the method further comprises, based at least on receiving the second message to the session management entity, transmitting, to the policy management entity, a response to the second message, the response to the second message indicates a third PCC rule, and installing and / or enforcing the third PCC rule requires dedicated bearers.

17. The method of any one of claims 8-16, wherein the method further comprises transmitting, to the session management entity, a notification message indicating the first PCC rule which requires a secondary packet data protocol (PDP) context activation procedure, and the error related to the first PCC rule is detected based on determining that the secondary PDP context activation procedure required for the first PCC rule cannot be initiated.

18. A method (800) performed by an application function (AF) for a network session of a user equipment (UE) in a network interworking scenario, the method comprising: receiving (s802), from a policy control function (PCF) (116), a notification message indicating that dedicated bearers are not supported by a RAN from which the UE is accessing and / or to which the UE is moved; based on receiving the notification message, determining (s804) a service that does not require dedicated bearers; and transmitting (s806), to the PCF, a response to the notification message, wherein the response to the notification information includes information about the determined service that does not require dedicated bearers.

19. The method of claim 18, wherein the network interworking scenario is a 5G core (5GC) and evolved packet core (EPC) interworking scenario.

20. The method of claim 18 or 19, wherein the method further comprises: receiving, from the PCF, another notification message indicating that dedicated bearers are supported by an updated RAN from which the UE is accessing and / or to which the UE is moved; based on receiving said another notification message, determining a service that requires dedicated bearers; and transmitting, to the PCF, a response to said another notification message, wherein the response to said another notification message includes information that requires dedicated bearers.

21. A computer program (900) comprising instructions (944) which when executed by processing circuitry (902) cause the processing circuitry to perform the method of any one of claims 1-20.

22. A carrier containing the computer program of claim 21, wherein the carrier is one of an electronic signal, an optical signal, a radio signal, and a computer readable storage medium.

23. A session management node (SMF+PGW-C) (118) for managing a network session of a user equipment (UE) in a network interworking scenario, the session management function being configured to: determine (s602) that the UE is accessing from and / or moved to a radio access network (RAN); based at least on the determination, detect (s604) an error related to a first policy and charging control (PCC) rule; and based at least on detecting the error related to the first PCC rule, transmit (s606), to a policy control function (PCF) (116), a first message which indicates the error related to the first PCC rule, wherein the error related to the first PCC rule is that the first PCC rule could not be successfully installed and / or enforced because the RAN does not support dedicated bearers which are needed for installing and / or enforcing the first PCC rule.

24. The session management node of claim 23, wherein the session management function is configured to perform the method of any one of claims 2-7.

25. A policy control node (116) for a network session of a user equipment (UE) in a network interworking scenario, the PCF being configured to: receive (s702), from a session management function (SMF+PGW-C) (118), a first message which indicates an error related to a first policy and charging control (PCC) rule, wherein the error related to the first PCC rule is that the first PCC rule could not be successfully installed and / or enforced because a first RAN from which the UE is accessing and / or to which the UE is moved does not support dedicated bearers which are needed for installing and / or enforcing the first PCC rule.

26. The policy control node of claim 25, wherein the policy control node is configured to perform the method of any one of claims 9-17.

27. An application node for a network session of a user equipment (UE) in a network interworking scenario, the AF being configured to: receive (s802), from a policy control function (PCF) (116), a notification message indicating that dedicated bearers are not supported by a RAN from which the UE is accessing and / or to which the UE is moved; based on receiving the notification message, determine (s804) a service that does not require dedicated bearers; and transmit (s806), to the PCF, a response to the notification message, wherein the response to the notification information includes information about the determined service that does not require dedi cated b ear er s .

28. The application node of claim 27, wherein the application node is configured to perform the method of any one of claims 19 and 20.

29. An apparatus (900) comprising: processing circuitry (902); and a memory (941), said memory containing instructions executable by said processing circuitry, whereby the apparatus is operative to perform the method of any one of claims 1-20.

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