Patent Description:
Examples of mobile or wireless telecommunication systems may include the Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access Network (UTRAN), Long Term Evolution (LTE) Evolved UTRAN (E-UTRAN), LTE-Advanced (LTE-A), MulteFire, LTE-A Pro, and/or fifth generation (<NUM>) radio access technology or new radio (NR) access technology. <NUM> wireless systems refer to the next generation (NG) of radio systems and network architecture. A <NUM> system is mostly built on a <NUM> new radio (NR), but a <NUM> (or NG) network can also build on the E-UTRA radio. It is estimated that NR provides bitrates on the order of <NUM>-<NUM> Gbit/s or higher, and can support at least service categories such as enhanced mobile broadband (eMBB) and ultra-reliable low-latency-communication (URLLC) as well as massive machine type communication (mMTC). NR is expected to deliver extreme broadband and ultra-robust, low latency connectivity and massive networking to support the Internet of Things (IoT). With IoT and machine-to-machine (M2M) communication becoming more widespread, there will be a growing need for networks that meet the needs of lower power, low data rate, and long battery life. The next generation radio access network (NG-RAN) represents the RAN for <NUM>, which can provide both NR and LTE (and LTE-Advanced) radio accesses. It is noted that, in <NUM>, the nodes that can provide radio access functionality to a user equipment (i.e., similar to the Node B, NB, in UTRAN or the evolved NB, eNB, in LTE) may be named next-generation NB (gNB) when built on NR radio and may be named next-generation eNB (NG-eNB) when built on E-UTRA radio. 3GPP C4-<NUM> discloses PGW selection and related Create Session Request and Create Session Response messages. 3GPP C4-<NUM> relates to the restoration of PDN connections after a PGW-C/SMF change, wherein the PGW-C/SMF returns a PGW Change Info IE in the Create Session Response message which contains a PGW Set FQDN.

In the following description, the invention is described with particular reference to <FIG> and <FIG>, while the description of the remaining figures is provided for illustrative purposes for a better understanding of the invention.

It will be readily understood that the components of certain example embodiments, as generally described and illustrated in the figures herein, may be arranged and designed in a wide variety of different configurations. Thus, the following detailed description of some example embodiments of systems, methods, apparatuses, and computer program products for packet data network gateway (PGW) selection for network slicing, is not intended to limit the scope of certain embodiments but is representative of selected example embodiments.

Additionally, if desired, the different functions or procedures discussed below may be performed in a different order and/or concurrently with each other. Furthermore, if desired, one or more of the described functions or procedures may be optional or may be combined. As such, the following description should be considered as illustrative of the principles and teachings of certain example embodiments, and not in limitation thereof.

Certain embodiments described herein may relate to procedures to support the evolved packet system (EPS) and <NUM> system (5GS) interworking. For EPS and 5GS interworking, several problems can arise. In particular, one problem may arise when a UE establishes a connection with EPS and then later moves to 5GS. During a UE's packet data network (PDN) connection establishment in EPS, the mobility management entity (MME) may select a PGW. This selection may be based, in part, on the acess point name (APN) / data network name (DNN).

Generally, an APN/DNN may be supported by multiple network slices. On the other hand, a PGW may support different network slices. An MME, not aware of the network slices (which were basically introduced with <NUM>), could therefore, during establishment of a UE's PDN connection, select a PGW that supports the requested APN/DNN, but the selected PGW might not support the network slice the user has a subscription for. This would then, later on, cause EPS to 5GS mobility failure when the UE moves from EPS to 5GS.

For instance, for a network deployment with EPS and 5GS, when the same APN/DNN is supported by different network slices and the dedicated core network (DCN) feature is not supported in EPS, or in the visited public land mobile network (VPLMN) in roaming scenarios, the MME may select (during the establishment of the UE's PDN connection) a PGW supporting the requested APN/DNN, but not supporting the network slice (NS) for which the user has a subscription.

As an example, one APN/DNN can be supported by two different network slices, NS1 and NS2 (e.g., having single network slice assistance information (S-NSSAI) <NUM> and S-NSSAI <NUM>, respectively), where a first PGW (PGW1) supports the APN/DNN but just NS1 (S-NSSAI <NUM>) and a second PGW (PGW2) supports the APN/DNN but just NS2 (S-NSSAI <NUM>). The UE has a user subscription for this APN/DNN and just NS2 (S-NSSAI <NUM>).

During the establishment of the UE's PDN connection in EPS, the MME does a domain name system (DNS) query using the APN fully qualified domain name (FQDN) set to the requested APN, and discovers that PGW1 and PGW2 support the APN/DNN. Since the MME does not know the 5GS subscription of the UE, nor which network slice each PGW supports, it may select the "wrong" PGW, PGW <NUM>, and attempt to establish the PDN connection towards PGW1.

If PGW1 has an interface with the unified data management (UDM), it can retrieve the (<NUM>) user subscription. From the user subscription, PGW1 may determine that it does not support the network slice for which the user has a subscription (e.g., NS2), and PGW1 may discover another PGW, here PGW2, that supports the requested APN/DNN and the network slice (NS2) subscribed by the UE. Not doing so would cause EPS to 5GS mobility failure when the UE later moves from EPS to 5GS.

Extensions have been proposed that enable the first PGW initially selected by an MME to forward a Create Session Request to a second PGW. This proposed solution requires the following signaling paths: for the Create Session Request: MME->SGW->PGW1->PGW2, and for the Create Session Response: PGW2->PGW1->SGW->MME.

In this respect, PGW1 forwards the Create Session Request to PGW2, during the PDN connection establishment. PGW1 includes the sender fully qualified tunnel endpoint identifier (F-TEID) received from the SGW, and sets the source IP address and the source UDP port as its own IP address. The PGW2 is not aware that the Create Session Request message was transferred from another PGW.

The proposed solution presents several issues. First, redirection from PGW1 to PGW2 assumes that both PGWs are not in slices isolated from each other, as the Create Session Response message is sent back to the forwarding PGW that forwards it to the SGW. It is therefore assumed that GTPv2/UDP/IP connectivity between the source PGW/session management function (SMF) and the target PGW/SMF which are in different slices is allowed in such network deployment. As such, such a solution does not work for deployments where network slices are isolated with no connectivity between the PGWs.

Further, the proposed solution adds significant complexity to the PGW (PGW1). PGW1 has to store the SGW source address/port received in the Create Session Request in order to set the correct destination address/port when forwarding the Create Session Response. To handle possible SGW retransmissions of the Create Session Request, PGW1 should also store the PGW2 address, so that retransmissions are sent to the same PGW2. This requires building a new "session database" where the retrieval key might be the SGW F-TEID, because TEID is not allocated in PGW1. Receiving GTP-C messages (CSResponse) where TEID in the header is not locally assigned may also be problematic for the internal routing of the messages and might cause issues if the TEID assigned by SGW is also assigned by PGW1 for another session.

So, with the proposed solution, a Create Session Request cannot be forwarded between two PGWs from isolated network slices and consequenlty EPS to 5GS mobility procedure may fail in such case. Additionally, it adds significant complexity to the PGW implementation.

Therefore, as will be discussed in detail below, some example embodiments provide an approach that can overcome at least the issues posed above.

According to one example embodiment, if a PGW (e.g., PGW1) reecives a Create Session Request from the MME and then determines that it does not support the network slice that the UE has a user subscription for, the PGW (e.g., PGW1) may reject the Create Session Request towards the MME with a new cause indicating "PGW mismatch with network slice subscribed by the UE" and with the FQDN or IP address of a different PGW (e.g., PGW <NUM>) that the MME should use for establishing the PDN connection. In certain embodiments, the PGW (e.g., PGW1) may discover the different PGW (e.g., PGW2) using a network repository function (NRF) network function (NF) discovery procedure and/or through local configuration. The MME can then request to establish the PDN connection towards that different PGW (PGW2).

In another example embodiment, the PGW (PGW1) may forward the Create Session Request to the other PGW (PGW2), but include a new information element (IE) in the forwarded Create Session Request to convey the SGW source port information (i.e., source port number of the Create Session Request received by PGW1) such as to enable PGW2 to send a successful Create Session Response directly to the SGW, i.e., with the following signalling paths: Create Session Request: MME->SGW->PGW1->PGW2, and Create Session Response: PGW2->SGW->MME. Hence, the IE included by PGW1 in the forwarded Create Session Request indicates to the PGW2 to direclty reply back to the SGW, rather than via PGW1.

<FIG> illustrates an example signaling diagram, according to certain example embodiments. In the example of <FIG>, the signaling diagram may include a MME, SGW, PGW1 supporting slice <NUM>, and PGW2 supporting slice <NUM>.

As illustrated in the example of <FIG>, at <NUM>, a MME may transmit, to a receiving PGW (PGW1) via the SGW, a Create Session Request to establish a PDN connection for a UE in EPS. Upon receipt of the Create Session Request, if the receiving PGW (PGW1) determines, after retrieving the user subscription from UDM, that it (PGW1) does not support the network slice of the APN/DNN for which the UE has a subscription, the PGW1 may, at <NUM>, reject the Create Session Request towards the MME with a new error cause indicating a PGW mismatch with the network slice subscribed by the UE and with the FQDN or IP address of a different PGW (PGW <NUM>). Thus, in an embodiment, the error cause for "PGW mismatch with network slice subscribed by the UE" may be used by the PGW in the Create Session Response message during an EPS to 5GS mobility procedure, to indicate that the PGW is not serving the network slice subscribed by the UE for the APN/DNN. In certain embodiments, the PGW (e.g., PGW1) may discover the other PGW (e.g., PGW2) using a NRF NF discovery procedure (i.e., NF discovery request with query parameters identifying the APN/DNN and the network slice subscribed by the UE) and/or through local configuration. As further illustrated in the example of <FIG>, the MME can then, at <NUM>, transmit a Create Session Request to establish the PDN connection towards PGW2. As also illustrated in the example of <FIG>, at <NUM>, the MME may receive a Create Session Response from PGW2.

According to some example embodiments, new IEs for an alternative PGW-C/SMF FQDN and alternative PGW-C/SMF IP address are shown in Table <NUM> below. These alternative IEs may be defined in the Create Session Response.

As described above, <FIG> is provided as one example. Other examples are possible, according to some embodiments.

<FIG> illustrates an example signaling diagram, according to another example embodiments. In the example of <FIG>, the signaling diagram may include a MME, SGW, PGW1 supporting slice <NUM>, and PGW2 supporting slice <NUM>.

As illustrated in the example of <FIG>, at <NUM>, a MME may transmit, to a receiving PGW (PGW1) via the SGW, a Create Session Request to establish a PDN connection for a UE in EPS. In the example of <FIG>, at <NUM>, PGW1 may forward the Create Session Request to PGW2, and include a new IE in the forwarded Create Session Request to convey the SGW UDP port number (i.e., source UDP port number of the Create Session Request received by PGW1) such as to enable PGW2 to send a successful Create Session Response directly to the SGW. Thus, in this embodiment, the Create Session Request may be sent along the following signalling path: MME->SGW->PGW1->PGW2, and the Create Session Response may be sent along the following singalling path: PGW2->SGW->MME.

According to the example embodiment of <FIG>, a new IE for a SGW source UDP Port Number, as shown in Table <NUM> belowk, may be defined in the Create Session Request.

As further illustrated in the example of <FIG>, upon receipt of this new IE, at <NUM>, PGW2 may send the Create Session Response directly to the SGW IP address and UDP port number. The SGW IP address is already available in the existing message (in Sender F-TEID IE).

As outlined above, <FIG> is provided as one example. It is noted that other examples are possible, according to some embodiments.

<FIG> illustrates a flow chart of a method of packet data network gateway (PGW) reselection for network slicing, according to a claimed embodiment. In certain example embodiments, the flow diagram of <FIG> may be performed by a network entity or network node in a communications system, such as LTE or <NUM> NR. According to the invention, the network entity performing one or more of the procedures depicted in <FIG> includes or is included in a network gateway, such as a PGW. <FIG> includes one or more procedures performed by PGW1 in the examples of <FIG>.

As illustrated in <FIG>, the method includes, at <NUM>, receiving a request from a network entity, such as a MME, to establish PDN connection for at least one UE in an EPS. The request is a create session request to establish the packet data network (PDN) connection in the evolved packet system (EPS). The method includes, at <NUM>, retrieving a subscription for the at least one UE. The retrieving <NUM> includes retrieving the user subscription from a UDM or other location in which the user subscription may be stored. According to the invention, the method includes, at <NUM>, determining from the user subscription that the PGW does not support a network slice of an APN and/or DNN for which the at least one UE has a subscription.

When it is determined, after retrieving the user subscription, that the PGW does not support the network slice of the APN and/or DNN for which the at least one UE has a subscription, the method includes discovering an address of another PGW that supports the APN and/or DNN and the network slice, e.g., using a NRF NF discovery procedure or through local configuration and, at <NUM>, transmitting a response to the network entity. The response includes an indication that there is a PGW mismatch with the network slice subscribed to by the at least one UE and includes an address of the other PGW that supports the network slice. For example, the transmitting <NUM> may include transmitting a create session error response rejecting the request towards the MME with a new error cause indicating the PGW mismatch with the network slice subscribed by the UE and with the FQDN or IP address of another PGW that supports the network slice.

As outlined above, <FIG> shows a method of the invention. It is noted that other examples are possible, according to some embodiments.

<FIG> illustrates an example flow chart of a method of packet data network gateway (PGW) reselection for network slicing, according to one embodiment. In certain example embodiments, the example flow diagram of <FIG> may be performed by a network entity or network node in a communications system, such as LTE or <NUM> NR. In some example embodiments, the network entity performing one or more of the procedures depicted in <FIG> may include or be included in a network gateway, such as a PGW, or the like. In some embodiments, as an example, <FIG> may include one or more procedures performed by PGW1 in the examples of <FIG>.

As illustrated in the example of <FIG>, the method may include, at <NUM>, receiving at a PGW, from a MME, a Create Session Request to establish a PDN connection for a UE in EPS. In an embodiment, the method may include, at <NUM>, retrieving a subscription for the at least one UE. For example, the retrieving <NUM> may include retrieving the user subscription from a UDM or other location in which the user subscription may be stored. According to an embodiment, the method may include, at <NUM>, determining from the user subscription that the PGW does not support a network slice of an APN and/or DNN for which the at least one UE has a subscription. In an embodiment, the method may include, at <NUM>, forwarding the Create Session Request to an other PGW that supports the network slice for which the at least one UE has a subscription, and including a new IE in the forwarded Create Session Request to convey the SGW UDP port number (i.e., source UDP port number of the Create Session Request received by the PGW) such as to enable the other PGW to send a successful Create Session Response directly to the SGW. Upon receipt of this new IE, the other PGW may send the Create Session Response directly to the SGW IP address and UDP port number.

<FIG> illustrates a flow chart of a method of packet data network gateway (PGW) reselection for network slicing, according to a claimed embodiment. The flow diagram of <FIG> is performed by a network entity or network node in a communications system, such as LTE or <NUM> NR. In some example embodiments, the network entity performing one or more of the procedures depicted in <FIG> may include or be included in a node responsible for signaling, paging, authentication and/or authorization of a mobile device or UE. For instance, in one embodiment, the entity performing the method of <FIG> may include a MME. In some embodiments, as an example, <FIG> may include one or more procedures performed by the MME in the examples of <FIG>.

As illustrated in <FIG>, the method includes, at <NUM>, transmitting a request to a PGW to establish a PDN connection for at least one UE in an EPS. The request is a create session request to establish the PDN connection in the EPS. The method includes, at <NUM>, receiving a response from the PGW. The response includes an indication that the PGW does not support a network slice subscribed to by the at least one UE and includes an address of another PGW that supports the network slice. For example, the response may include an indication that there is a PGW mismatch with the network slice subscribed to by the at least one UE and may include an address of another PGW that supports the network slice. In one example, the receiving <NUM> may include receiving a create session error response rejecting the request towards the MME with a new error cause indicating the PGW mismatch with the network slice subscribed by the UE and with the FQDN or IP address of another PGW that supports the network slice.

The method further includes, at <NUM>, transmitting a request to establish the PDN connection towards the another PGW that supports the network slice. According to an embodiment, the method may include, at <NUM>, receiving a create session response from the another PGW.

<FIG> illustrates an example flow chart of a method of packet data network gateway (PGW) reselection for network slicing, according to one embodiment. In certain example embodiments, the example flow diagram of <FIG> may be performed by a network entity or network node in a communications system, such as LTE or <NUM> NR. In some example embodiments, the network entity performing one or more of the procedures depicted in <FIG> may include or be included in a network gateway, such as a PGW, or the like. In some embodiments, as an example, <FIG> may include one or more procedures performed by PGW2 in the examples of <FIG>.

As illustrated in the example of <FIG>, the method may include, at <NUM>, receiving a Create Session Request with a new SGW source UDP port IE. The method may include, at <NUM>, transmitting a Create Session Response directly to the SGW indicated in the SGW source UDP port IE.

<FIG> illustrates an example of an apparatus <NUM> according to an embodiment. In an embodiment, apparatus <NUM> may be a node, host, or server in a communications network or serving such a network. For example, apparatus <NUM> may be a network node, a sensing node, satellite, base station, a Node B, an evolved Node B (eNB), <NUM> Node B or access point, next generation Node B (NG-NB or gNB), TRP, HAPS, integrated access and backhaul (IAB) node, and/or a WLAN access point, associated with a radio access network, such as a LTE network, <NUM> or NR. In some example embodiments, apparatus <NUM> may be a gateway, such as a PGW.

In fact, processor <NUM> may include one or more of general-purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs), field-programmable gate arrays (FPGAs), application-specific integrated circuits (ASICs), and processors based on a multi-core processor architecture, or any other processing means, as examples.

Processor <NUM> may perform functions associated with the operation of apparatus <NUM>, which may include, for example, precoding of antenna gain/phase parameters, encoding and decoding of individual bits forming a communication message, formatting of information, and overall control of the apparatus <NUM>, including processes related to management of communication or communication resources.

For example, memory <NUM> can be comprised of any combination of random access memory (RAM), read only memory (ROM), static storage such as a magnetic or optical disk, hard disk drive (HDD), or any other type of non-transitory machine or computer readable media, or other appropriate storing means.

In some embodiments, apparatus <NUM> may also include or be coupled to one or more antennas <NUM> for transmitting and receiving signals and/or data to and from apparatus <NUM>. Apparatus <NUM> may further include or be coupled to a transceiver <NUM> configured to transmit and receive information. The transceiver <NUM> may include, for example, a plurality of radio interfaces that may be coupled to the antenna(s) <NUM>, or may include any other appropriate transceiving means. The radio interfaces may correspond to a plurality of radio access technologies including one or more of GSM, NB-IoT, LTE, <NUM>, WLAN, Bluetooth, BT-LE, NFC, radio frequency identifier (RFID), ultrawideband (UWB), MulteFire, and the like. The radio interface may include components, such as filters, converters (for example, digital-to-analog converters and the like), mappers, a Fast Fourier Transform (FFT) module, and the like, to generate symbols for a transmission via one or more downlinks and to receive symbols (for example, via an uplink).

Additionally or alternatively, in some embodiments, apparatus <NUM> may include an input and/or output device (I/O device), or an input/output means.

According to some embodiments, processor <NUM> and memory <NUM> may be included in or may form a part of processing circuitry/means or control circuitry/means. In addition, in some embodiments, transceiver <NUM> may be included in or may form a part of transceiver circuitry/means.

As used herein, the term "circuitry" may refer to hardware-only circuitry implementations (e.g., analog and/or digital circuitry), combinations of hardware circuits and software, combinations of analog and/or digital hardware circuits with software/firmware, any portions of hardware processor(s) with software (including digital signal processors) that work together to cause an apparatus (e.g., apparatus <NUM>) to perform various functions, and/or hardware circuit(s) and/or processor(s), or portions thereof, that use software for operation but where the software may not be present when it is not needed for operation.

As introduced above, in certain embodiments, apparatus <NUM> may be a network element or RAN node, such as a base station, access point, Node B, eNB, gNB, TRP, HAPS, IAB node, WLAN access point, or the like. In one example embodiment, apparatus <NUM> may be a PGW. According to certain embodiments, apparatus <NUM> may be controlled by memory <NUM> and processor <NUM> to perform the functions associated with any of the embodiments described herein. For example, in some embodiments, apparatus <NUM> may be configured to perform one or more of the processes depicted in any of the flow charts or signaling diagrams described herein, such as those illustrated in <FIG> or any other method described herein. In some embodiments, as discussed herein, apparatus <NUM> may be configured to perform a procedure relating to reselection of a PGW for network slicing, for example.

According to an embodiment, apparatus <NUM> may be controlled by memory <NUM> and processor <NUM> to receive a request from a network entity, such as a MME, to establish PDN connection for at least one UE in an EPS. For example, the request may be a create session request to establish the PDN connection in the EPS. In an embodiment, apparatus <NUM> may be controlled by memory <NUM> and processor <NUM> to retrieve a subscription for the at least one UE. For example, apparatus <NUM> may be controlled by memory <NUM> and processor <NUM> to retrieve the user subscription from a UDM or other location in which the user subscription may be stored. According to an embodiment, apparatus <NUM> may be controlled by memory <NUM> and processor <NUM> to determine from the user subscription that the apparatus <NUM> does not support a network slice of an APN and/or DNN for which the at least one UE has a subscription.

In some embodiments, when it is determined, after retrieving the user subscription, that the apparatus <NUM> does not support the network slice of the APN and/or DNN for which the at least one UE has a subscription, apparatus <NUM> may be controlled by memory <NUM> and processor <NUM> to transmit a response to the network entity. The response may include an indication that there is a PGW mismatch with the network slice subscribed to by the at least one UE and may include an address of another PGW that supports the network slice. For example, in an embodiment, apparatus <NUM> may be controlled by memory <NUM> and processor <NUM> to transmit a create session error response rejecting the request towards the MME with a new error cause indicating the PGW mismatch with the network slice subscribed by the UE and with the FQDN or IP address of another PGW that supports the network slice.

<FIG> illustrates an example of an apparatus <NUM> according to another embodiment. In an embodiment, apparatus <NUM> may be a node, network element, host, or server in a communications network or associated with such a network. For example, apparatus <NUM> may be a network node, a sensing node, satellite, base station, a Node B, an evolved Node B (eNB), <NUM> Node B or access point, next generation Node B (NG-NB or gNB), TRP, HAPS, integrated access and backhaul (IAB) node, and/or a WLAN access point, associated with a radio access network, such as a LTE network, <NUM> or NR. In some example embodiments, apparatus <NUM> may be a node responsible for signaling, paging, authentication and/or authorization of a mobile device or UE. For instance, in one embodiment, apparatus <NUM> may be or may include a MME.

As discussed above, according to some embodiments, apparatus <NUM> may be a node responsible for signaling, paging, authentication and/or authorization of a mobile device or UE, such as a MME, for example. According to certain embodiments, apparatus <NUM> may be controlled by memory <NUM> and processor <NUM> to perform the functions associated with any of the embodiments described herein, such as one or more of the operations illustrated in, or described with respect to, <FIG> or any other method described herein. For example, in an embodiment, apparatus <NUM> may be controlled to perform a process relating to reselection of a PGW for network slicing.

According to certain embodiments, apparatus <NUM> may be controlled by memory <NUM> and processor <NUM> to transmit a request to a PGW to establish a PDN connection for at least one UE in an EPS. For example, the request may be a create session request to establish the PDN connection in the EPS. According to an embodiment, apparatus <NUM> may be controlled by memory <NUM> and processor <NUM> to receive a response from the PGW. The response may include an indication that the PGW does not support a network slice subscribed to by the at least one UE and may include an address of another PGW that supports the network slice. For example, the response may include an indication that there is a PGW mismatch with the network slice subscribed to by the at least one UE and may include an address of a "correct" PGW that supports the network slice. In an embodiment, the response may be a create session error response rejecting the request towards the MME with a new error cause indicating the PGW mismatch with the network slice subscribed by the UE and with the FQDN or IP address of another PGW that supports the network slice.

In certain embodiments, apparatus <NUM> may be controlled by memory <NUM> and processor <NUM> to transmit a request to establish the PDN connection towards the other, "correct" PGW that supports the network slice. According to an embodiment, apparatus <NUM> may be controlled by memory <NUM> and processor <NUM> to receive a create session response from the other PGW.

In some embodiments, an apparatus (e.g., apparatus <NUM> and/or apparatus <NUM>) may include means for performing a method, a process, or any of the variants discussed herein. Examples of the means may include one or more processors, memory, controllers, transmitters, receivers, and/or computer program code for causing the performance of the operations.

In view of the foregoing, certain example embodiments provide several technological improvements, enhancements, and/or advantages over existing technological processes and constitute an improvement at least to the technological field of wireless network control and management. As discussed above, certain example embodiments provide procedures for PGW reselection for network slicing in order to support EPS and 5GS interworking. For example, certain embodiments allow a PGW, which receives a request from a network entity to establish a PDN connection for a UE in an EPS, but does not support a network slice for which the UE has a subscription, to determine a correct PGW and indicate that correct PGW to the requesting entity. As such, example embodiments provide an efficient method for PGW reselection. Accordingly, the use of certain example embodiments results in improved functioning of communications networks and their nodes, such as base stations, eNBs, gNBs, and/or IoT devices, UEs or mobile stations.

In some example embodiments, the functionality of any of the methods, processes, signaling diagrams, algorithms or flow charts described herein may be implemented by software and/or computer program code or portions of code stored in memory or other computer readable or tangible media, and may be executed by a processor.

In some example embodiments, an apparatus may include or be associated with at least one software application, module, unit or entity configured as arithmetic operation(s), or as a program or portions of programs (including an added or updated software routine), which may be executed by at least one operation processor or controller. Programs, also called program products or computer programs, including software routines, applets and macros, may be stored in any apparatus-readable data storage medium and may include program instructions to perform particular tasks. A computer program product may include one or more computer-executable components which, when the program is run, are configured to carry out some example embodiments. The one or more computer-executable components may be at least one software code or portions of code. Modifications and configurations required for implementing the functionality of an example embodiment may be performed as routine(s), which may be implemented as added or updated software routine(s). In one example, software routine(s) may be downloaded into the apparatus.

As an example, software or computer program code or portions of code may be in source code form, object code form, or in some intermediate form, and may be stored in some sort of carrier, distribution medium, or computer readable medium, which may be any entity or device capable of carrying the program. Such carriers may include a record medium, computer memory, read-only memory, photoelectrical and/or electrical carrier signal, telecommunications signal, and/or software distribution package, for example. The computer readable medium or computer readable storage medium may be a non-transitory medium.

In other example embodiments, the functionality of example embodiments may be performed by hardware or circuitry included in an apparatus, for example through the use of an application specific integrated circuit (ASIC), a programmable gate array (PGA), a field programmable gate array (FPGA), or any other combination of hardware and software. In yet another example embodiment, the functionality of example embodiments may be implemented as a signal, such as a non-tangible means, that can be carried by an electromagnetic signal downloaded from the Internet or other network.

Example embodiments described herein may apply to both singular and plural implementations, regardless of whether singular or plural language is used in connection with describing certain embodiments. For example, an embodiment that describes operations of a single network node may also apply to embodiments that include multiple instances of the network node, and vice versa.

Claim 1:
A method performed by a packet data network gateway (PGW1), comprising:
receiving (<NUM>), from a network entitiy, a create session request message to establish a packet data network, PDN, connection for a user equipment, UE, in an evolved packet system, EPS;
retrieving (<NUM>), from a unified data management, UDM, a subscription for the UE;
determining (<NUM>) from the subscription that the packet data network gateway (PGW1) does not support a network slice for which the UE has a subscription;
discovering another packet data network gateway (PGW2) that supports the network slice for which the UE has a subscription; and
transmitting (<NUM>) a session create response message to the network entity, the create session response message comprising an indication that there is a packet data network gateway (PGW1) mismatch with the network slice subscribed by the UE and an address of the another packet data network gateway (PGW2) that supports the network slice for which the UE has a subscription.