Efficient techniques for user-plane path switch

Abstract

Embodiments include methods for a radio access network (RAN) control plane (CP) entity configured for selective user plane (UP) path switch signaling. Such methods include determining that a path switch is needed for one or more user equipment (UE) protocol data unit (PDU) sessions with a user plane function (UPF) in a core network (CN) coupled to the RAN. The path switch is from a first path that includes a source RAN UP entity to a second path that includes a target RAN UP entity. Such methods include evaluating one or more policy rules related to path switch procedures and selectively performing an in-band path switch procedure or a CP path switch procedure for the UE, based on a result of the evaluation. Other embodiments include complementary methods for a UPF, as well as network equipment configured to implement RAN CP entities and UPFs.

Description

[0001] EFFICIENT TECHNIQUES FOR USER-PLANE PATH SWITCH

[0002] TECHNICAL FIELD

[0003] The present disclosure relates generally to the field of wireless networks and more specifically to improving user plane path switch during handover or other mobility operations involving a user equipment (UE).

[0004] BACKGROUND

[0005] Currently the fifth generation (5G) of cellular systems is being standardized within the Third-Generation Partnership Project (3GPP). 5G is developed for maximum flexibility to support multiple and substantially different use cases. These include enhanced mobile broadband (eMBB), machine type communications (MTC), ultra-reliable low latency communications (URLLC), side-link device-to-device (D2D), and several other use cases.

[0006] Figure 1 illustrates a high-level view of an exemplary 5G network architecture, consisting of a Next Generation Radio Access Network (NG-RAN, 199) and a 5G Core (5GC, 198). The NG-RAN can include one or more gNodeB’s (gNBs) connected to the 5GC via one or more NG interfaces, such as gNBs (100, 150) connected via respective interfaces (102, 152). More specifically, the gNBs can be connected to one or more Access and Mobility Management Functions (AMFs) in the 5GC via respective NG-C interfaces and to one or more User Plane Functions (UPFs) in 5GC via respective NG-U interfaces. The 5GC can include various other network functions (NFs), such as Session Management Function(s) (SMF).

[0007] Although not shown, in some deployments the 5GC can be replaced by an Evolved Packet Core (EPC), which conventionally has been used together with a fourth generation (4G) Long- Term Evolution (LTE) Evolved UMTS RAN (E-UTRAN). In such deployments, gNBs (e.g., 100, 150) can connect to one or more Mobility Management Entities (MMEs) in EPC 198 via respective Sl-C interfaces. Similarly, gNBs can connect to one or more Serving Gateways (SGWs) in EPC via respective NG-U interfaces.

[0008] In addition, the gNBs can be connected to each other via one or more Xn interfaces, such as Xn interface (140) between gNBs (100, 150). The radio technology for the NG-RAN is often referred to as “New Radio” (NR). With respect to the NR interface to UEs, each of the gNBs can support frequency division duplexing (FDD), time division duplexing (TDD), or a combination thereof. Each of the gNBs can serve a geographic coverage area including one or more cells and, in some cases, can also use various directional beams to provide coverage in the respective cells. In general, a DL “beam” is a coverage area of a network-transmitted reference signal (RS) that may be measured or monitored by a UE. NG RAN logical nodes (e.g., gNB 100) include a Central Unit (CU or gNB-CU, e.g., 110) and one or more Distributed Units (DU or gNB-DU, e.g., 120, 130). CUs are logical nodes that host higher-layer protocols and perform various gNB functions such controlling the operation of DUs. DUs are decentralized logical nodes that host lower layer protocols and can include, depending on the functional split option, various subsets of the gNB functions. Each CU and DU can include various circuitry needed to perform their respective functions, including processing circuitry, communication interface circuitry e.g., transceivers), and power supply circuitry.

[0009] A gNB-CU connects to one or more gNB-DUs over respective Fl logical interfaces (e.g., 122 and 132 shown in Figure 1). However, a gNB-DU can be connected to only a single gNB-CU. The gNB-CU and its connected gNB-DU(s) are only visible to other gNBs and the 5GC as a gNB. In other words, the Fl interface is not visible beyond gNB-CU.

[0010] Figure 2 shows a logical architecture for an NG-RAN node (e.g., gNB or ng-eNB) arranged in the split CU / DU architecture, such as gNB (100) in Figure 1. This logical architecture separates the CU into CP and UP functionality, called CU-CP and CU-UP respectively. Furthermore, each of the NG, Xn, and Fl interfaces is split into a CP interface (e.g., NG-C) and a UP interface (e.g., NG-U). Moreover, the CU-UP and CU-CP can communicate via an El interface. Each DU may be connected to only one CU-CP, and each CU-UP may be connected to only one CU-CP. However, a single DU may be connected to multiple CU-UPs under the control of the same CU- CP, or a single CU-UP may be connected to multiple DUs under the control of the same CU-CP. The terms “Central Entity” and “Distributed Entity” in Figure 2 refer to physical network nodes.

[0011] One change in 5G networks (e.g., in 5GC) is that traditional peer-to-peer interfaces and protocols found in earlier-generation networks are modified and / or replaced by a Service Based Architecture (SBA) in which Network Functions (NFs) - such as AMF, SMF, and UPF discussed above - provide one or more services to one or more service consumers. Furthermore, the services are composed of various “service operations”, which are more granular divisions of the overall service functionality.

[0012] The UP and CP are also decoupled in the 5GC. SMF is responsible for CP interaction with the decoupled UP, including creating, updating, and removing Protocol Data Unit (PDU) sessions and managing session context with the UPF, e.g., for event reporting. For example, SMF performs data flow detection (based on filter definitions included in PCC rules), online and offline charging interactions, and policy enforcement. SMF also provides various Nsmf services operations that other NFs can use to communicate with it.

[0013] The access and mobility management function (AMF) terminates the NG-RAN / CP interface and handles all mobility and connection management of UEs. AMF communicates with SMFs via an N11 reference point and with the NG- RAN via an N2 reference point. AMF also provides various Namf services operations that other NFs can use to communicate with it.

[0014] UPF is responsible for handling of UP traffic based on rules received from SMF, including packet inspection and different enforcement actions (e.g., event detection and reporting). UPFs communicate with NG-RAN via an N3 reference point and with SMFs via an N4 reference point.

[0015] Seamless mobility is a key feature of 3GPP radio access technologies (RATs). In general, a RAN (e.g., NG-RAN) configures a UE to perform and report radio resource management (RRM) measurements to assist network-controlled mobility decisions, such as for handover from a serving cell to a neighbor cell. Seamless handovers ensure that the UE moves around in the coverage area of different cells without excessive interruption to data transmission.

[0016] Handover of a UE between cells served by different gNBs require signaling between these two gNBs (called “source gNB” and “target gNB”) over the Xn interface, also referred to as “Xn handover”. Conventional Xn handover finishes with a Path Switch Request message from target gNB over N2 interface to AMF, which requests the AMF to change downlink (DL, i.e., to UE) UP and CP routing from the source gNB to the target gNB. The path switch request will cause the AMF to invoke the SMF, which will send an update message to request the UPF(s) serving the UE to change DL routing. The Path Switch Request will also cause the AMF to update the RAN CP location in the AMF, i.e., by establishing a UE-associated signaling connection between the AMF and the target gNB. Note that the term “path switch” refers to changing the DL routing, in response to a Path Switch Request.

[0017] SUMMARY

[0018] This procedure to produce a path switch upon UE handover is time consuming and involves a lot of signaling for AMF and SMF, both of which add very little value to the procedure. One possible improvement is for the target gNB to send a Path Switch Request directly to the UPF using “in-band signaling” that does not go through AMF / SMF in 5GC CP. However, this approach also has various drawbacks, such as the CP not being aware of the path switch in the UP. As such, the CP is unable to take various actions that may be needed in relation to Xn handovers of UEs.

[0019] An object of embodiments of the present disclosure is to address these and related problems, issues, and / or difficulties, thereby facilitating UE mobility between cells in a RAN (e.g., NG-RAN).

[0020] Some embodiments of the present disclosure include methods e.g., procedures) for radio access network (RAN) CP entity configured for selective UP path switch signaling. These exemplary methods include determining that a path switch is needed for one or more user equipment (UE) protocol data unit (PDU) sessions with a UPF in a core network (CN, e.g., 5GC) coupled to the RAN. The path switch is from a first path that includes a source RAN UP entity to a second path that includes a target RAN UP entity. These exemplary methods also include evaluating one or more policy rules related to path switch procedures. These exemplary methods also include selectively performing an in-band path switch procedure or a CP path switch procedure for the UE, based on a result of the evaluation.

[0021] In some embodiments, evaluating the one or more policy rules is based on one or more conditions related to one or more of the following: the UE, the RAN CP entity, the target RAN UP entity, and the UPF. In some of these embodiments, the one or more conditions include one or more of the following:

[0022] • whether a different RAN CP entity is needed in conjunction with the path switch;

[0023] • whether all of the UE’s existing quality-of-service (QoS) flows can be supported by the target RAN UP entity;

[0024] • whether the target RAN UP entity supports different features than the source RAN UP entity;

[0025] • whether the UPF is reachable by the target RAN UP entity;

[0026] • transport latency from the target RAN UP entity to the UPF; and

[0027] • area assignments of the target RAN UP entity and the UPF.

[0028] In some variants of these embodiments, the one or more policy rules include one or more compatibility rules for the area assignments of the target RAN UP entity and the UPF.

[0029] In some of these embodiments, selectively performing an in-band path switch procedure or a CP path switch procedure for the UE based on a result of the evaluation includes the following operations:

[0030] • performing a CP path switch procedure when the evaluation indicates that the one or more conditions meet at least one of the policy rules; and

[0031] • performing an in-band path switch procedure when the evaluation indicates that the one or more conditions do not meet at least one of the policy rules.

[0032] In some variants of these embodiments, performing a CP path switch procedure includes sending a Path Switch Request message to an AM) in the CN, and receiving a Path Switch Response message from the AMF. In some further variants, the path switch is related to a handover of the UE and Path Switch Request message is an N2 PATH SWITCH REQUEST message. In other further variants, the path switch is related to a PDU session modification for the UE and the Path Switch Request message is a PDU Session Modification Request message. Other embodiments include methods (e.g., procedures) for a UPF of a CN coupled to a RAN. In general, these exemplary methods are complementary to the exemplary methods for a RAN CP entity summarized above and described in more detail herein.

[0033] These exemplary methods include receiving an in-band Path Switch Request message indicating a path switch for one or more UE PDU sessions with the UPF. These exemplary methods also include evaluating one or more policy rules related to path switch procedures. These exemplary methods also include selectively notifying one or more NFs of the CN CP about the path switch for the UE PDU sessions with the UPF, based on a result of the evaluation.

[0034] In some embodiments, evaluating the one or more policy rules is based on one or more of the following inputs:

[0035] • an identity of the UE;

[0036] • a downlink (DE) data address in target RAN UP entity;

[0037] • transport latency from the UPF to the target RAN UP entity; and

[0038] • one or more information elements (lEs) of the in-band Path Switch Request message.

[0039] In some of these embodiments, the one or more lEs include one or more of the following:

[0040] • an indication that the UPF should notify the CN CP about the path switch;

[0041] • a list of the UE’s PDU sessions that failed to setup in the target RAN UP entity,

[0042] • a list of the UE’s existing quality-of-service (QoS) flows that are not supported by the target RAN UP entity,

[0043] • a list of features supported by the target RAN UP entity;

[0044] • an indication that the target RAN UP entity is assigned to a different area than the source RAN UP entity; and

[0045] • an area assignment of the target RAN UP entity.

[0046] In some variants of these embodiments, the one or more policy rules include one or more compatibility rules for the area assignments of the target RAN UP entity and the UPF.

[0047] In some of these embodiments, selectively notifying the one or more NFs of the CN CP about the path switch based on a result of the evaluation includes the following operations:

[0048] • notifying the one or more NFs of the CN CP when the evaluation indicates that the one or more inputs meet at least one of the policy rules; and

[0049] • refraining from notifying the one or more NFs of the CN CP when the evaluation indicates that the one or more inputs do not meet at least one of the policy rules.

[0050] In some variants of these embodiments, notifying the one or more NFs of the CN CP comprises sending an N4 Session Modification Notify message to a session management function (SMF) of the CN CP. In some further variants, the N4 Session Modification Notify includes an explicit or implicit indication for the SMF to notify an AMF of the CN CP about the path switch.

[0051] Other embodiments include RAN CP entities and UPFs (or implementing network equipment) configured to perform operations corresponding to any of the exemplary methods described herein. Other embodiments also include non-transitory, computer-readable media storing computer-executable instructions that, when executed by processing circuitry, configure such RAN CP entities and UPFs to perform operations corresponding to any of the exemplary methods described herein.

[0052] These and other embodiments described herein may provide advantages of both CP and in-band signaling techniques for UP path switch without some or all of the problems, issues, and / or difficulties of the two techniques. For example, embodiments can facilitate fast handover and low CP load due to the use of in-band signaling while retaining the versatility of CP decision making about UPF allocation and placement due UPF notification about a path switch. As another example, embodiments can facilitate fast handover and low CP load due to the use of in-band signaling as default while retaining the versatility of CP decision making for exceptional cases. Embodiments may be particularly advantageous when RAN CP is more centralized than the RAN UP, which may be the situation for future cloud-based RAN deployments.

[0053] These and other objects, features, and advantages of the present disclosure will become apparent upon reading the following Detailed Description in view of the Drawings briefly described below.

[0054] BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 shows a high-level view of an exemplary 5G network architecture.

[0056] Figure 2 shows a logical architecture for an NG-RAN node arranged in a split CU / DU architecture, such as illustrated in Figure 1.

[0057] Figure 3 shows a signaling flow for an exemplary handover for a UE from a source cell served by a source gNB to a target cell served by a target gNB.

[0058] Figure 4 shows a signaling flow for an exemplary PDU session modification procedure performed for UP relocation, based on CP signaling.

[0059] Figure 5 shows a signaling flow for another exemplary PDU session modification procedure performed for UP relocation, based on in-band signaling.

[0060] Figure 6 shows a signaling diagram of a path switch procedure based on selective (or conditional) in-band or CP signaling, according to some embodiments of the present disclosure.

[0061] Figure 7 shows an exemplary method (e.g., procedure) for a RAN CP entity, according to various embodiments of the present disclosure. Figure 8 shows an exemplary method (e.g., procedure) for a UPF, according to various embodiments of the present disclosure.

[0062] Figure 9 shows a communication system according to various embodiments of the present disclosure.

[0063] Figure 10 shows a network node according to various embodiments of the present disclosure.

[0064] Figure 11 is a block diagram of a virtualization environment in which functions implemented by some embodiments of the present disclosure may be virtualized.

[0065] Figure 12 illustrates communication between a host computing system, a network node, and a UE via multiple connections, at least one of which is wireless, according to various embodiments of the present disclosure.

[0066] DETAILED DESCRIPTION

[0067] Embodiments briefly summarized above will now be described more fully with reference to the accompanying drawings. These descriptions are provided by way of example to explain the subject matter to those skilled in the art and should not be construed as limiting the scope of the subject matter to only the embodiments described herein. More specifically, examples are provided below that illustrate the operation of various embodiments according to the advantages discussed above.

[0068] In general, all terms used herein are to be interpreted according to their ordinary meaning to a person of ordinary skill in the relevant technical field, unless a different meaning is expressly defined and / or implied from the context of use. All references to a / an / the element, apparatus, component, means, step, etc. are to be interpreted openly as referring to at least one instance of the element, apparatus, component, means, step, etc., unless explicitly stated otherwise or clearly implied from the context of use. The operations of any methods and / or procedures disclosed herein do not have to be performed in the exact order disclosed, unless an operation is explicitly described as following or preceding another operation and / or where it is implicit that an operation must follow or precede another operation. Any feature of any embodiment disclosed herein can apply to any other disclosed embodiment, as appropriate. Likewise, any advantage of any embodiment described herein can apply to any other disclosed embodiment, as appropriate.

[0069] Furthermore, the following terms are used throughout the description given below:

[0070] • Radio Access Node: As used herein, a “radio access node” (or equivalently “radio network node,” “radio access network node,” or “RAN node”) can be any node in a radio access network (RAN) that operates to wirelessly transmit and / or receive signals. Some examples of a radio access node include, but are not limited to, a base station (e.g., gNB in a 3GPP 5G / NR network or an enhanced or eNB in a 3GPP LTE network), base station distributed components (e.g., CU and DU), a high-power or macro base station, a low-power base station (e.g., micro, pico, femto, or home base station, or the like), an integrated access backhaul (IAB) node, a transmission point (TP), a transmission reception point (TRP), a remote radio unit (RRU or RRH), and a relay node.

[0071] • Core Network Node: As used herein, a “core network node” is any type of node in a core network. Some examples of a core network node include, e.g., a Mobility Management Entity (MME), a serving gateway (SGW), a PDN Gateway (P-GW), a Policy and Charging Rules Function (PCRF), an access and mobility management function (AMF), a session management function (SMF), a user plane function (UPF), a Charging Function (CHF), a Policy Control Function (PCF), an Authentication Server Function (AUSF), a location management function (EMF), or the like.

[0072] • Wireless Device: As used herein, a “wireless device” (or “WD” for short) is any type of device that is capable, configured, arranged and / or operable to communicate wirelessly with network nodes and / or other wireless devices. Communicating wirelessly can involve transmitting and / or receiving wireless signals using electromagnetic waves, radio waves, infrared waves, and / or other types of signals suitable for conveying information through air. Unless otherwise noted, the term “wireless device” is used interchangeably herein with the term “user equipment” (or “UE” for short), with both of these terms having a different meaning than the term “network node”.

[0073] • Radio Node: As used herein, a “radio node” can be either a “radio access node” (or equivalent term) or a “wireless device.”

[0074] • Network Node: As used herein, a “network node” is any node that is either part of the radio access network (e.g., a radio access node or equivalent term) or of the core network e.g., a core network node discussed above) of a cellular communications network. Functionally, a network node is network equipment capable, configured, arranged, and / or operable to communicate directly or indirectly with a wireless device and / or with other network nodes or equipment in the cellular communications network, to enable and / or provide wireless access to the wireless device, and / or to perform other functions (e.g., administration) in the cellular communications network.

[0075] • Node: As used herein, the term “node” (without prefix) can be any type of node that can in or with a wireless network (including RAN and / or core network), including a radio access node (or equivalent term), core network node, or wireless device. However, the term “node” may be limited to a particular type (e.g., radio access node, IAB node) based on its specific characteristics in any given context. The above definitions are not meant to be exclusive. In other words, various ones of the above terms may be explained and / or described elsewhere in the present disclosure using the same or similar terminology. Nevertheless, to the extent that such other explanations and / or descriptions conflict with the above definitions, the above definitions should control.

[0076] Note that the description given herein focuses on a 3GPP cellular communications system and, as such, 3GPP terminology or terminology similar to 3GPP terminology is oftentimes used. However, the concepts disclosed herein are not limited to a 3GPP system and can be applied to any communication system that may benefit from them.

[0077] As briefly mentioned above, handover of a UE between cells served by different gNBs require signaling between these two gNBs (called “source gNB” and “target gNB”) over the Xn interface, also referred to as “Xn handover”. Figure 3 shows a signaling flow for an exemplary handover for a UE from a source cell served by a source gNB to a target cell served by a target gNB, as described in 3GPP TS 38.300 (vl7.5.0).

[0078] In operation 0, which can be considered a prerequisite, the UE’s context within the source gNB contains information regarding roaming and access restrictions which were provided either at connection establishment or at the last TA update.

[0079] In operation 1, the source gNB configures the UE measurement procedures and the UE reports according to the measurement configuration. In operation 2, the source gNB decides to handover the UE, based on MeasurementReport and RRM information.

[0080] In operation 3, the source gNB sends a Handover Request message to the target gNB passing a transparent RRC container with necessary information to prepare the handover at the target side. The information includes at least the target cell ID, KgNB*, the C-RNTI of the UE in the source gNB, RRM-configuration including UE inactive time, basic AS -configuration including antenna Info and DL Carrier Frequency, the current QoS flow to DRB mapping rules applied to the UE, the SIB 1 information from source gNB, the UE capabilities for different RATs, protocol data unit (PDU) session related information, and can include the UE reported measurement information including beam-related information if available. The PDU session related information includes the slice information and QoS flow level QoS profile(s). The source gNB may also request a dual active protocol stack (DAPS) handover for one or more data radio bearers (DRBs). After issuing a Handover Request, the source gNB should not reconfigure the UE, including performing Reflective QoS flow to DRB mapping.

[0081] In operation 4, admission Control may be performed by the target gNB. Slice-aware admission control shall be performed if the slice information is sent to the target gNB. If the PDU sessions are associated with non-supported slices the target gNB shall reject such PDU Sessions. In operation 5, the target gNB prepares the handover with L1 / L2 and sends the HANDOVER REQUEST ACKNOWLEDGE to the source gNB, which includes a transparent container to be sent to the UE as an RRC message to perform the handover. The target gNB also indicates if a DAPS handover is accepted. As soon as the source gNB receives the HANDOVER REQUEST ACKNOWLEDGE, or as soon as the transmission of the handover command is initiated in the downlink, data forwarding may be initiated. For DRBs configured with DAPS, downlink PDCP SDUs are forwarded with SN assigned by the source gNB, until SN assignment is handed over to the target gNB in step 8b, for which the normal data forwarding follows as defined in 3GPP TS 38.300 section 9.2.3.2.3.

[0082] In operation 6, the source gNB triggers the Uu handover by sending an RRCReconfiguration message to the UE, containing the information required to access the target cell: at least the target cell ID, the new C-RNTI, the target gNB security algorithm identifiers for the selected security algorithms. It can also include a set of dedicated RACH resources, the association between RACH resources and SSB(s), the association between RACH resources and UE-specific CSI-RS configuration(s), common RACH resources, and system information of the target cell, etc. For DRBs configured with DAPS, the source gNB does not stop transmitting downlink packets until it receives the HANDOVER SUCCESS message from the target gNB in operation 8a. Note that conditional handover (CHO) cannot be configured simultaneously with DAPS handover.

[0083] In operation 7a, for DRBs configured with DAPS, the source gNB sends the EARLY STATUS TRANSFER message. The DL COUNT value conveyed in the EARLY STATUS TRANSFER message indicates PDCP SN and HFN of the first PDCP SDU that the source gNB forwards to the target gNB. The source gNB does not stop assigning SNs to downlink PDCP SDUs until it sends the SN STATUS TRANSFER message to the target gNB in operation 8b.

[0084] In operation 7, for DRBs not configured with DAPS, the source gNB sends the SN STATUS TRANSFER message to the target gNB to convey the uplink PDCP SN receiver status and the downlink PDCP SN transmitter status of DRBs for which PDCP status preservation applies (i.e., for RLC AM). The uplink PDCP SN receiver status includes at least the PDCP SN of the first missing UL PDCP SDU and may include a bit map of the receive status of the out of sequence UL PDCP SDUs that the UE needs to retransmit in the target cell, if any. The downlink PDCP SN transmitter status indicates the next PDCP SN that the target gNB shall assign to new PDCP SDUs, not having a PDCP SN yet. In case of DAPS handover, the uplink PDCP SN receiver status and the downlink PDCP SN transmitter status for a DRB with RLC-AM and not configured with DAPS may be transferred by the SN STATUS TRANSFER message in operation 8b instead of operation 7. For DRBs configured with DAPS, the source gNB may additionally send the EARLY STATUS TRANSFER message(s) between step 7 and step 8b, to inform discarding of already forwarded PDCP SDUs. The target gNB does not transmit forwarded downlink PDCP SDUs to the UE, whose COUNT is less than the conveyed DL COUNT value and discards them if transmission has not been attempted already.

[0085] In operation 8, the UE synchronises to the target cell and completes the RRC handover procedure by sending RRCReconfigurationComplete message to target gNB. In case of DAPS handover, the UE does not detach from the source cell upon receiving the RRCReconfiguration message. The UE releases the source resources and configurations and stops DL / UL reception / transmission with the source upon receiving an explicit release from the target node. From the RAN point of view, DAPS handover is considered to only be completed after the UE has released the source cell as explicitly requested from the target node. RRC suspend, a subsequent handover or inter-RAT handover cannot be initiated until the source cell has been released.

[0086] In operations 8a-b, in case of DAPS handover, the target gNB sends the HANDOVER SUCCESS message to the source gNB to inform that the UE has successfully accessed the target cell. In return, the source gNB sends the SN STATUS TRANSFER message for DRBs configured with DAPS for which the description in step 7 applies, and the normal data forwarding follows as defined in 3GPP TS 38.300 section 9.2.3.2.3.

[0087] The uplink PDCP SN receiver status and the downlink PDCP SN transmitter status are also conveyed for DRBs with RLC-UM in the SN STATUS TRANSFER message in step 8b, if configured with DAPS. For DRBs configured with DAPS, the source gNB does not stop delivering uplink QoS flows to the UPF until it sends the SN STATUS TRANSFER message in step 8b. The target gNB does not forward QoS flows of the uplink PDCP SDUs successfully received in-sequence to the UPF until it receives the SN STATUS TRANSFER message, in which UL HFN and the first missing SN in the uplink PDCP SN receiver status indicates the start of uplink PDCP SDUs to be delivered to the UPF. The target gNB does not deliver any uplink PDCP SDUs which has an UL COUNT lower than the provided.

[0088] In operation 9, the target gNB sends a PATH SWITCH REQUEST message to AMF to trigger 5GC to switch the DL data path towards the target gNB and to establish an NG-C interface instance towards the target gNB. In operation 10, the 5GC switches the DL UP data path towards the target gNB. In particular, in operation 10.1, the AMF sends an Nsmf_PDUSession_UpdateSMContext Request to the SMF, which in turn sends an N4 Session Modification Request message to the UPF in operation 10.2. Subsequently, in operation 10.3 the UPF responds to SMF with an N4 Session Modification Response message to SMF, which in turn sends an Nsmf_PDUSession_ UpdateSMContext Response to AMF in operation 10.4. The UPF sends one or more "end marker" packets on the old path to the source gNB per PDU session / tunnel and then can release any U- plane / TNL resources towards the source gNB. At this point, the path switch has been completed.

[0089] In operation 11 , the AMF confirms the PATH SWITCH REQUEST message of operation 9 with the PATH SWITCH REQUEST ACKNOWLEDGE message. In operation 12, upon reception of the PATH SWITCH REQUEST ACKNOWLEDGE message from the AMF, the target gNB sends the UE CONTEXT RELEASE to inform the source gNB about the success of the handover. The source gNB can then release radio and C-plane related resources associated to the UE context. Any ongoing data forwarding may continue.

[0090] The PATH SWITCH REQUEST message will also cause the AMF to update the RAN CP location in the AMF, i.e., by establishing a UE-associated signaling connection between the AMF and the target gNB. This procedure shown in Figure 3 involving a path switch upon UE handover is time consuming and involves a lot of signaling for AMF and SMF, both of which add very little value to the procedure.

[0091] In other cases, there are no changes in the RAN CP but there are changes in the RAN UP (e.g., some QoS Flows are rejected or modified by RAN). In such scenarios, as part of a PDU session modification procedure, the RAN CP can inform the SMF whether there has been a change in the RAN UP. This is another variant of how RAN UP changes are communicated to 5GC.

[0092] Figure 4 shows a signaling flow for an exemplary PDU session modification procedure performed for UP relocation. In Figure 4, the RAN is shown with three logical components: a source UP (e.g., CU-UP) for a UE, a target UP (e.g., CU-CP) for the UE, and a CP (e.g., CU-CP).

[0093] After the CP makes a UP relocation decision and exchange of user data is initiated between the UE and the target UP, the RAN CP sends a PDU Session Modification Request to the AMF, which causes the AMF to initiate a path switch for the UE in the UPF. Note that the PDU session modification procedure involves no UE handover; the reason for the RAN UP relocation may also be something else.

[0094] In particular, the AMF sends an Nsmf_PDUSession_UpdateSMContext Request to the SMF, which in turn sends an N4 Session Modification Request message to the UPF. The UPF responds to SMF with an N4 Session Modification Response message, which causes the SMF to send an Nsmf_PDUSession_UpdateSMContext Response to AMF. The UPF sends one or more "end marker" packets on the old path to the source gNB. Subsequently, the AMF sends a PDU Session Modification Response to the RAN CP.

[0095] Even though the path switch in Figure 4 does not involve UE handover, it nonetheless is time consuming and involves a lot of signaling for AMF and SMF, both of which add very little value to the procedure.

[0096] While the above-described procedures for path switch involve CP signaling, an alternate technique is for the target gNB to send a Path Switch Request directly to the UPF using “in- band” signaling that does not go through AMF / SMF in CN CP. This approach can reduce AMF / SMF load and path switch latency, as well as improve reliability in case of the CP being temporarily inaccessible from the UP. Put differently, UP path switches (e.g., due to handover or other reason) would work even if AMF / SMF is temporarily unavailable. Figure 5 shows a signaling flow for an exemplary PDU session modification procedure performed for UP relocation, including in-band signaling between RAN target UP and UPF. Note that AMF / SMF are not involved in the procedure shown in Figure 5.

[0097] However, the in-band signaling illustrated by Figure 5 has various problems, issues, and / or difficulties. For example, in larger networks transport connectivity may be segmented such that all gNBs do not have transport connectivity to all UPFs. If a UE is handed over to a gNB with no transport connectivity to the UE’s current UPF, in-band signaling is not possible. As another example, the CN CP may need to take perform other operations at UE handover in addition to path switch signaling to UPF, such as one or more of the following:

[0098] • inserting, removing, or relocating an intermediate UPF (I-UPF) for load balancing or other reasons;

[0099] • initiating relocation of the anchor UPF for the UE’s PDU session;

[0100] • accounting actions for the UE’s PDU session; and

[0101] • collection of statistics and / or sending relevant notifications to analytics functions (e.g., NWDAF) in the 5GC.

[0102] Because the CN CP (e.g., AMF / SMF) is not aware of a UP relocation (e.g., change in DE data address for the UE) done by in-band signaling, it cannot perform these operations when needed.

[0103] Embodiments of the present disclosure address these and other problems, difficulties, and / or issues by providing flexible and efficient techniques for path switch based on in-band signaling between target gNB to UPF. In some embodiments, the target gNB uses in-band signaling as default but can choose to use CP signaling under certain conditions. In other embodiments, the target gNB always uses in-band signaling with UPF, which notifies the CN CP (e.g., SMF) under certain conditions. In either of these embodiments, the conditions may be pre-defined (e.g., in 3GPP specification), CN configurable in RAN / UPF, operator configurable in RAN / UPF, or indirectly operator configurable via the CN CP.

[0104] Embodiments can provide various benefits and / or advantages. For example, embodiments may provide advantages of both CP and in-band signaling techniques for UP path switch without some or all of the problems, issues, and / or difficulties of the two techniques. For example, embodiments can facilitate fast handover and low CP load due to the use of in-band signaling while retaining the versatility of CP decision making about UPF allocation and placement due UPF notification about a path switch. As another example, embodiments can facilitate fast handover and low CP load due to the use of in-band signaling as default while retaining the versatility of CP decision making for exceptional cases. Embodiments may be particularly advantageous when RAN CP is more centralized than the RAN UP, which may be the situation for future cloud-based RAN deployments.

[0105] Figure 6 shows a signaling diagram of a path switch procedure based on selective (or conditional) in-band or CP signaling, according to some embodiments of the present disclosure. The procedure shown in Figure 6 involves a UE (610), a RAN (620), an AMF (630) and an SMF (640) in 5GC CP, and a UPF (650) in 5GC UP. The RAN includes a source UP entity (621, e.g., CU-UP / DU), a target UP entity (622, e.g., CU-UP / DU), and a CP entity (623, e.g., CU-CP).

[0106] Initially, the UE is communicating user data with the UPF via the source UP entity. The RAN CP entity determines a need for a handover or UP relocation for the UE from the source UP to a target UP, such as illustrated in Figures 3-4. For example, the target UP entity may include a target gNB comprising a CU-UP entity and a coupled DU serving a target cell for a UE handover. The RAN CP entity then determines whether to perform an in-band or CP path switch procedure by evaluating one or more policy rules based on various conditions related to the UE, the target RAN UP, and / or the UPF, which may include any of the following:

[0107] • whether a different RAN CP entity is needed in conjunction with the UP path switch;

[0108] • whether all of the UE’s existing QoS flows can be accepted by the target RAN UP entity;

[0109] • whether the target RAN UP entity supports different features than the source RAN UP entity;

[0110] • whether the UPF is reachable by the target RAN UP entity;

[0111] • transport latency from the target RAN UP entity to the UPF; and

[0112] • predefined area memberships of the target RAN UP and the UPF, along with compatibility rules for the area memberships.

[0113] In various embodiments, the policy rules may be predefined (e.g., in 3GPP specification), configured in the RAN by the network operator, or dynamically adjusted in the RAN by the 5GC (e.g., AMF, SMF, and / or PCF) for each UE or for each PDU session. The following are some illustrative examples of how the RAN CP entity may evaluate one or more policy rules based on various inputs:

[0114] • Perform CP path switch if the RAN CP also changes, since signaling to AMF is already required.

[0115] • Perform CP path switch if there are changes to the QoS flows due to the target RAN UP (e.g., gNB) not supporting some of the UE’s existing QoS flows. This allows the 5GC CP to initiate QoS Flow change procedures to account for this.

[0116] • Perform CP path switch if the UPF(s) is / are unreachable from the target RAN UP entity. For example, the underlying transport network topology may include disjoint segments, with the UPF being in a different segment different than the target gNB. In this case the 5GC CP can assign an I-UPF to bridge or relocate the anchor UPF. Note that if such topology restrictions exist, the target gNB must be aware of which UPFs it can communicate with for in-band path switch.

[0117] • Perform CP path switch if a latency between the target RAN UP and the UPF(s) is greater than a maximum allowed latency. In this case, the CP path switch signaling allows the 5GC CP to relocate the UE to UPF(s) that have latency less than the maximum allowed latency. This rule may be particularly relevant for “edge” services that need to remain close to the UE. In case the target RAN UP (e.g., gNB) does not know its latency to the selected UPF, the policy rule may allow or prohibit connections to a UPF whose latency to the target RAN UP is unknown.

[0118] • Perform CP path switch if the areas assigned to the gNB and the UPF are not compatible, according to the compatibility rules. These rules may be operator configurable, which allows the operator to control UPF selection via assignments of areas to gNBs and UPFs.

[0119] • Perform CP path switch if the set of features supported by the target RAN UP (e.g., gNB) is different from the source RAN UP such that feature enablement is needed by the CP.

[0120] The above policy rule evaluations may be used individually or in any combination. In case the individual rule or combination of rules is not met, the RAN CP entity performs in-band patch switch for the UE.

[0121] The large, dashed rectangles in Figure 6 show the options for in-band path and CP path switch signaling based on the result of the RAN CP entity’s evaluation of the one or more policy rules. In case the one or more policy rules are met, the RAN CP entity sends a Path Switch Request in the CP to the AMF, which then involves the SMF and UPF based on the signaling shown in Figures 3-4. Note that this CP Path Switch Request may be an N2 PATH SWITCH REQUEST message such as shown in Figure 3 or a PDU Session Modification Request message such as shown in Figure 4. In case the one or more policy rules are not met, the RAN CP entity sends a Path Switch Command (or similarly named) message to the target RAN UP entity, which causes the target RAN UP entity to send an in-band Path Switch Request to the UPF.

[0122] In some embodiments, the RAN CP entity may be integrated with the target RAN UP entity, so the Path Switch Command is internal signaling. In other embodiments, the RAN CP may be remote from the target RAN UP entity (e.g., in cloud), so the Path Switch Command is carried over a connecting transport network. For example, if the RAN is arranged in the split node architecture shown in Figures 1-2 such that the RAN CP entity is a CU-CP and the target RAN UP entity includes a CU-UP coupled to the CU-CP, the Path Switch Command can be included in a message over the El interface between CU-CP and CU-UP. Example El messages include Bearer Context Creation and Modification Request.

[0123] As an alternative, the in-band Path Switch Request may be sent by the RAN CP entity to the UPF, in which case the Path Switch Command to the target RAN UP entity is not used. As another alternative, the in-band Path Switch Request may be sent automatically by the target RAN UP entity (e.g., in UL packets) without triggering by the RAN CP entity, in which case the Path Switch Command to the target RAN UP entity is not used.

[0124] Returning to Figure 6, assuming that an in-band Path Switch Request is sent, the UPF responds with a Path Switch Request Acknowledge message, which may be an N2 PATH SWITCH RESPONSE message such as shown in Figure 3 or a PDU Session Modification Response message such as shown in Figure 4. The UPF also determines whether to notify the 5GC CP of the path switch by evaluating one or more policy rules based on various inputs, which may include any of the following:

[0125] • UE identity;

[0126] • DL data address in target RAN UP;

[0127] • Information elements (IES) in the in-band Path Switch Request message, such as: o an indication (e.g., flag) for the UPF to notify the 5GC CP about the path switch, o a list of PDU Sessions that failed to setup, o a list of rejected QoS Flows, o a list of supported features, and / or o an indication that the UE is or will be located in a different network area due to the path switch.

[0128] For example, the flag, the list of PDU sessions, and / or the list of rejected QoS flows may be included in the in-band Path Switch Request message when the target RAN UP entity cannot support all existing PDU Sessions and / or all existing QoS Flows for the UE. In such case, action from the 5GC CP (e.g., SMF) is needed to address these conditions. The indication of UE being in a different network area may be included based on network configuration, implementation, or policies.

[0129] In case the one or more policy rules are met, the UPF sends an N4 Session Modification Notify (or similarly named) message to notify the SMF of the UE’s path switch to a new DL data address. In some embodiments, this message may cause the SMF to send an Namf_PDUSession_ UpdateSMContext Notify (or similarly named) message that notifies the AMF of this change. In case the one or more policy rules are not met, the UPF refrains from sending the N4 Session Modification Notify (or similarly named) message to the SMF.

[0130] In various embodiments, the policies rules evaluated by the UPF may be predefined (e.g., in 3GPP specification), configured in the UPF by the network operator, or dynamically configured by the SMF for each UPF (e.g., when establishing an association with a UPF over N4 interface) or for each PDU session (e.g., at PDU session creation / modification or added as a subscription by the SMF to UPF-published events).

[0131] Regardless of whether the 5GC CP was notified of the path switch by a CP Path Switch Request from the RAN CP entity or by the UPF, the 5GC CP is now able to perform necessary session-related CP operations such as one or more of the following:

[0132] • removing PDU sessions and / or QoS flows, and informing the UE of this operation;

[0133] • inserting, removing, or relocating an I-UPF for load balancing or other reasons;

[0134] • initiating relocation of the anchor UPF for the UE’s PDU session;

[0135] • accounting actions for the UE’s PDU session; and

[0136] • collection of statistics and / or sending relevant notifications to analytics functions (e.g., NWDAF) in the 5GC.

[0137] The embodiments described above can be further illustrated with reference to Figures 7-8, which depict exemplary methods e.g., procedures) for a RAN CP entity and a UPF, respectively. Put differently, various features of the operations described below correspond to various embodiments described above. The exemplary methods shown in Figures 7-8 can be used cooperatively to provide benefits, advantages, and / or solutions to problems described herein. Although Figures 7-8 illustrate the exemplary methods by specific blocks in particular orders, the operations corresponding to the blocks can be performed in different orders than shown and can be combined and / or divided into blocks and / or operations having different functionality than shown. Optional blocks or operations are indicated by dashed lines.

[0138] More specifically, Figure 7 illustrates an exemplary method (e.g., procedure) for a RAN CP entity configured for selective path switch signaling, according to various embodiments of the present disclosure. The exemplary method shown in Figure 7 can be performed by a RAN CP entity (e.g., CU-CP or implementing network equipment) such as described elsewhere herein. The exemplary method includes the operations of block 720, where the RAN CP entity determines that a path switch is needed for one or more user equipment (UE) protocol data unit (PDU) sessions with a user plane function (UPF) in a core network (CN) coupled to the RAN. The path switch is from a first path that includes a source RAN UP entity to a second path that includes a target RAN UP entity. The exemplary method includes the operations of block 730, where the RAN CP entity evaluates one or more policy rules related to path switch procedures. The exemplary method includes the operations of block 740, where the RAN CP entity selectively performs an in-band path switch procedure or a CP path switch procedure for the UE, based on a result of the evaluation in block 730.

[0139] In some embodiments, evaluating the one or more policy rules in block 730 is based on one or more conditions related to one or more of the following: the UE, the RAN CP entity, the target RAN UP entity, and the UPF. In some of these embodiments, the one or more conditions include one or more of the following:

[0140] • whether a different RAN CP entity is needed in conjunction with the path switch;

[0141] • whether all of the UE’s existing quality-of-service (QoS) flows can be supported by the target RAN UP entity;

[0142] • whether the target RAN UP entity supports different features than the source RAN UP entity;

[0143] • whether the UPF is reachable by the target RAN UP entity;

[0144] • transport latency from the target RAN UP entity to the UPF; and

[0145] • area assignments of the target RAN UP entity and the UPF.

[0146] In some variants of these embodiments, the one or more policy rules include one or more compatibility rules for the area assignments of the target RAN UP entity and the UPF.

[0147] In some of these embodiments, selectively performing an in-band path switch procedure or a CP path switch procedure for the UE based on a result of the evaluation in block 740 includes the following operations, labelled with corresponding sub-block numbers:

[0148] • (741) performing a CP path switch procedure when the evaluation indicates that the one or more conditions meet at least one of the policy rules; and

[0149] • (742) performing an in-band path switch procedure when the evaluation indicates that the one or more conditions do not meet at least one of the policy rules.

[0150] In some variants of these embodiments, performing a CP path switch procedure in subblock 741 includes sending a Path Switch Request message to an access and mobility management function (AMF) in the CN, and receiving a Path Switch Response message from the AMF. In some further variants, the path switch is related to a handover of the UE and Path Switch Request message is an N2 PATH SWITCH REQUEST message. In other further variants, the path switch is related to a PDU session modification for the UE and the Path Switch Request message is a PDU Session Modification Request message.

[0151] In some variants of these embodiments, the CP path switch procedure is performed based on one or more of the following results of the evaluation in block 730:

[0152] • a different RAN CP entity is needed in conjunction with the path switch;

[0153] • one or more of the UE’s existing QoS flows cannot be supported by the target RAN UP entity.

[0154] • the UPF is unreachable by the target RAN UP entity.

[0155] • the transport latency from the target RAN UP to the UPF is greater than a maximum allowed latency.

[0156] • the transport latency from the target RAN UP to the UPF is unknown;

[0157] • the area assignments of the target RAN UP entity and the UPF are incompatible; and

[0158] • the target RAN UP entity supports different features than the source RAN UP entity, which requires feature enablement in the CN CP.

[0159] In some variants of these embodiments, performing an in-band path switch procedure in sub-block 742 includes sending a Path Switch Command message to the target RAN UP entity. In some further variants, the Path Switch Command message includes one or more of the following:

[0160] • an indication that the target RAN UP entity should request the UPF to notify the CN CP about the path switch for the UE;

[0161] • a list of the UE’s PDU sessions that failed to setup in the target RAN UP entity;

[0162] • a list of the UE’s existing quality-of-service (QoS) flows that cannot be supported in the target RAN UP entity;

[0163] • a list of supported features; and

[0164] • an indication that the UE will be located in a different network area due to the path switch. In some variants of these embodiments, the RAN CP entity is a centralized unit CP (CU-

[0165] CP) of a RAN node, the target RAN UP entity is a centralized unit UP (CU-UP) of the RAN node, and the Path Switch Command message is, or is included in, a message on an El interface between the CU-CP and the CU-UP. In some further variants, the CU-CP is remote from the CU-UP and / or the CU-CP is hosted by cloud computing environment.

[0166] In some embodiments, the policy rules evaluated in block 730 are predefined. In other embodiments, the exemplary method also includes the operations of block 710, where the RAN CP entity receives the policy rules from one of the following: • an operations / administration / maintenance (OAM) system coupled to the RAN, wherein the received policy rules are applicable to all UEs and PDU sessions; or

[0167] • a network function of the CN, wherein the received policy rules are specific to one or more of the following: the UE, or each of the UE’s PDU sessions with the UPF.

[0168] In addition, Figure 8 illustrates an exemplary method (e.g., procedure) for a UPF of a core network (CN) coupled to a RAN, according to various embodiments of the present disclosure. The exemplary method shown in Figure 8 can be performed by a UPF or network equipment that implements a UPF, such as described elsewhere herein.

[0169] The exemplary method includes the operations of block 820, where the UPF receives an in-band Path Switch Request message indicating a path switch for one or more UE PDU sessions with the UPF. The exemplary method includes the operations of block 830, where the UPF evaluates one or more policy rules related to path switch procedures. The exemplary method includes the operations of block 840, where the UPF selectively notifies one or more NFs of the CN CP about the path switch for the UE PDU sessions with the UPF, based on a result of the evaluation in block 830.

[0170] In some embodiments, evaluating the one or more policy rules in block 830 is based on one or more of the following inputs:

[0171] • an identity of the UE;

[0172] • a downlink (DE) data address in target RAN UP entity;

[0173] • transport latency from the UPF to the target RAN UP entity; and

[0174] • one or more information elements (IES) of the in-band Path Switch Request message.

[0175] In some of these embodiments, the one or more IEs include one or more of the following:

[0176] • an indication that the UPF should notify the CN CP about the path switch;

[0177] • a list of the UE’s PDU sessions that failed to setup in the target RAN UP entity,

[0178] • a list of the UE’s existing quality-of-service (QoS) flows that are not supported by the target RAN UP entity,

[0179] • a list of features supported by the target RAN UP entity;

[0180] • an indication that the target RAN UP entity is assigned to a different area than the source RAN UP entity; and

[0181] • an area assignment of the target RAN UP entity.

[0182] In some variants of these embodiments, the one or more policy rules include one or more compatibility rules for the area assignments of the target RAN UP entity and the UPF. In some of these embodiments, selectively notifying the one or more NFs of the CN CP about the path switch based on a result of the evaluation in block 840 includes the following operations, labelled with corresponding sub-block numbers:

[0183] • (841) notifying the one or more NFs of the CN CP when the evaluation indicates that the one or more inputs meet at least one of the policy rules; and

[0184] • (842) refraining from notifying the one or more NFs of the CN CP when the evaluation indicates that the one or more inputs do not meet at least one of the policy rules.

[0185] In some variants of these embodiments, notifying the one or more NFs of the CN CP comprises sending an N4 Session Modification Notify message to a session management function (SMF) of the CN CP. In some further variants, the N4 Session Modification Notify includes an explicit or implicit indication for the SMF to notify an access and mobility management function (AMF) of the CN CP about the path switch.

[0186] In some of these embodiments, the one or more NFs of the CN CP are notified based on one or more of the following results of the evaluation in block 830:

[0187] • the in-band Path Switch Request messages includes an indication that the UPF should notify the CN CP about the path switch; and

[0188] • the DL data address in the target RAN UP entity is not reachable by the UPF;

[0189] • the transport latency from the UPF to the target RAN UP entity is greater than a maximum allowed latency; and

[0190] • the transport latency from the UPF to the target RAN UP entity is unknown.

[0191] In some of these embodiments, the one or more NFs of the CN CP are notified when evaluation of the one or more policy rules based on the one or more IES in the in-band Path Switch Request message indicates one or more of the following:

[0192] • one or more of the UE’s PDU sessions failed to setup in the target RAN UP entity;

[0193] • one or more of the UE’s existing QoS flows are not supported by the target RAN UP entity;

[0194] • the target RAN UP entity supports one or more features that require feature enablement in the CN CP; and

[0195] • the area assignments of the target RAN UP entity and the UPF are incompatible.

[0196] In some embodiments, the policy rules are predefined. In other embodiments, the exemplary method also includes the operations of block 810, where the UPF receives the policy rules from one of the following:

[0197] • an 0AM system coupled to the CN, wherein the received policy rules are applicable to all UEs and PDU sessions; or

[0198] • a session management function (SMF) of the CN CP, wherein the received policy rules are specific to the UPF or to each of the UE’s PDU sessions with the UPF. In some embodiments, the path switch is associated with one of the following procedures for the UE: handover from a source cell served by the source RAN UP entity to a target cell served by the target RAN UP entity, or PDU session modification.

[0199] Although various embodiments are described above in terms of methods, techniques, and / or procedures, the person of ordinary skill will readily comprehend that such methods, techniques, and / or procedures can be embodied by various combinations of hardware and software in various systems, communication devices, computing devices, control devices, apparatuses, non-transitory computer-readable media, computer program products, etc.

[0200] Figure 9 shows an example of a communication system 900 in accordance with some embodiments. In this example, communication system 900 includes a telecommunication network 902 that includes an access network 904 (e.g., RAN) and a core network 906, which includes one or more core network nodes 908. Access network 904 includes one or more access network nodes, such as network nodes 910a-b (one or more of which may be generally referred to as network nodes 910), or any other similar 3GPP access nodes or non-3GPP access points.

[0201] Moreover, as will be appreciated by those of skill in the art, a network node is not necessarily limited to an implementation in which a radio portion and a baseband portion are supplied and integrated by a single vendor. Thus, it will be understood that network nodes include disaggregated implementations or portions thereof. For example, in some embodiments, telecommunication network 902 includes one or more Open-RAN (ORAN) network nodes. An ORAN network node is a node in telecommunication network 902 that supports an ORAN specification (e.g., a specification published by the O-RAN Alliance, or any similar organization) and may operate alone or together with other nodes to implement one or more functionalities of any node in telecommunication network 902, including one or more network nodes 910 and / or core network nodes 908.

[0202] Examples of an ORAN network node include an open radio unit (O-RU), an open distributed unit (O-DU), an open central unit (O-CU), including an O-CU control plane (O-CU- CP) or an O-CU user plane (O-CU-UP), a RAN intelligent controller (near-real time or non-real time) hosting software or software plug-ins, such as a near-real time control application (e.g., xApp) or a non-real time control application (e.g., rApp), or any combination thereof (the adjective “open” designating support of an ORAN specification). The network node may support a specification by, for example, supporting an interface defined by the ORAN specification, such as an Al, Fl, Wl, El, E2, X2, Xn interface, an open fronthaul user plane interface, or an open fronthaul management plane interface. Moreover, an ORAN access node may be a logical node in a physical node. Furthermore, an ORAN network node may be implemented in a virtualization environment (described further below) in which one or more network functions are virtualized. For example, the virtualization environment may include an O-Cloud computing platform orchestrated by a Service Management and Orchestration Framework via an 0-2 interface defined by the 0-RAN Alliance or comparable technologies. Network nodes 910 facilitate direct or indirect connection of UEs, such as by connecting UEs 912a-d (one or more of which may be generally referred to as UEs 912) to core network 906 over one or more wireless connections.

[0203] Example wireless communications over a wireless connection include transmitting and / or receiving wireless signals using electromagnetic waves, radio waves, infrared waves, and / or other types of signals suitable for conveying information without the use of wires, cables, or other material conductors. Moreover, in different embodiments, communication system 900 may include any number of wired or wireless networks, network nodes, UEs, and / or any other components or systems that may facilitate or participate in the communication of data and / or signals whether via wired or wireless connections. Communication system 900 may include and / or interface with any type of communication, telecommunication, data, cellular, radio network, and / or other similar type of system.

[0204] UEs 912 may be any of a wide variety of communication devices, including wireless devices arranged, configured, and / or operable to communicate wirelessly with network nodes 910 and other communication devices. Similarly, network nodes 910 are arranged, capable, configured, and / or operable to communicate directly or indirectly with UEs 912 and / or with other network nodes or network equipment in telecommunication network 902 to enable and / or provide network access, such as wireless network access, and / or to perform other functions, such as administration in telecommunication network 902.

[0205] In the depicted example, core network 906 connects network nodes 910 to one or more hosts, such as host 916. These connections may be direct or indirect via one or more intermediary networks or devices. In other examples, network nodes may be directly coupled to hosts. Core network 906 includes one or more core network nodes (e.g., 908) that are structured with hardware and software components. Features of these components may be substantially similar to those described with respect to the UEs, network nodes, and / or hosts, such that the descriptions thereof are generally applicable to the corresponding components of core network node 908. Example core network nodes include functions of one or more of a Mobile Switching Center (MSC), Mobility Management Entity (MME), Home Subscriber Server (HSS), Access and Mobility Management Function (AMF), Session Management Function (SMF), Authentication Server Function (AUSF), Subscription Identifier De-concealing function (SIDF), Unified Data Management (UDM), Security Edge Protection Proxy (SEPP), Network Exposure Function (NEF), and / or a User Plane Function (UPF). Host 916 may be under the ownership or control of a service provider other than an operator or provider of access network 904 and / or telecommunication network 902, and may be operated by the service provider or on behalf of the service provider. Host 916 may host a variety of applications to provide one or more service. Examples of such applications include live and pre-recorded audio / video content, data collection services such as retrieving and compiling data on various ambient conditions detected by a plurality of UEs, analytics functionality, social media, functions for controlling or otherwise interacting with remote devices, functions for an alarm and surveillance center, or any other such function performed by a server.

[0206] As a whole, communication system 900 of Figure 9 enables connectivity between the UEs, network nodes, and hosts. In that sense, the communication system may be configured to operate according to predefined rules or procedures, such as specific standards that include, but are not limited to: Global System for Mobile Communications (GSM); Universal Mobile Telecommunications System (UMTS); Long Term Evolution (LTE), and / or other suitable 2G, 3G, 4G, 5G standards, or any applicable future generation standard (e.g., 6G); wireless local area network (WLAN) standards, such as the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standards (WiFi); and / or any other appropriate wireless communication standard, such as the Worldwide Interoperability for Microwave Access (WiMax), Bluetooth, Z-Wave, Near Field Communication (NFC) ZigBee, LiFi, and / or any low-power wide-area network (LPWAN) standards such as LoRa and Sigfox.

[0207] In some examples, telecommunication network 902 is a cellular network that implements 3GPP standardized features. Accordingly, telecommunication network 902 may support network slicing to provide different logical networks to different devices that are connected to telecommunication network 902. For example, telecommunication network 902 may provide Ultra Reliable Low Latency Communication (URLLC) services to some UEs, while providing Enhanced Mobile Broadband (eMBB) services to other UEs, and / or Massive Machine Type Communication (mMTC) / Massive loT services to yet further UEs.

[0208] In some examples, UEs 912 are configured to transmit and / or receive information without direct human interaction. For instance, a UE may be designed to transmit information to access network 904 on a predetermined schedule, when triggered by an internal or external event, or in response to requests from access network 904. Additionally, a UE may be configured for operating in single- or multi-RAT or multi- standard mode. For example, a UE may operate with any one or combination of Wi-Fi, NR (New Radio) and LTE, i.e. being configured for multi-radio dual connectivity (MR-DC), such as E-UTRAN (Evolved-UMTS Terrestrial Radio Access Network) New Radio - Dual Connectivity (EN-DC). In the example, hub 914 communicates with access network 904 to facilitate indirect communication between one or more UEs (e.g., UE 912c and / or 912d) and network nodes (e.g., network node 910b). In some examples, hub 914 may be a controller, router, content source and analytics, or any of the other communication devices described herein regarding UEs. For example, hub 914 may be a broadband router enabling access to core network 906 for the UEs. As another example, hub 914 may be a controller that sends commands or instructions to one or more actuators in the UEs. Commands or instructions may be received from the UEs, network nodes 910, or by executable code, script, process, or other instructions in hub 914. As another example, hub 914 may be a data collector that acts as temporary storage for UE data and, in some embodiments, may perform analysis or other processing of the data. As another example, hub 914 may be a content source. For example, for a UE that is a VR headset, display, loudspeaker or other media delivery device, hub 914 may retrieve VR assets, video, audio, or other media or data related to sensory information via a network node, which hub 914 then provides to the UE either directly, after performing local processing, and / or after adding additional local content. In still another example, hub 914 acts as a proxy server or orchestrator for the UEs, in particular if one or more of the UEs are low energy loT devices.

[0209] Hub 914 may have a constant / persistent or intermittent connection to network node 910b. Hub 914 may also allow for a different communication scheme and / or schedule between hub 914 and UEs (e.g., UE 912c and / or 912d), and between hub 914 and core network 906. In other examples, hub 914 is connected to core network 906 and / or one or more UEs via a wired connection. Moreover, hub 914 may be configured to connect to an M2M service provider over access network 904 and / or to another UE over a direct connection. In some scenarios, UEs may establish a wireless connection with network nodes 910 while still connected via hub 914 via a wired or wireless connection. In some embodiments, hub 914 may be a dedicated hub - that is, a hub whose primary function is to route communications to / from the UEs from / to network node 910b. In other embodiments, hub 914 may be a non-dedicated hub - that is, a device which is capable of operating to route communications between the UEs and network node 910b, but which is additionally capable of operating as a communication start and / or end point for certain data channels.

[0210] Figure 10 shows a network node 1000 in accordance with some embodiments. Examples of network nodes include, but are not limited to, access points (APs) (e.g., radio access points), base stations (e.g., radio base stations, Node Bs, eNBs, gNBs), and O-RAN nodes or components of an O-RAN node (e.g., O-RU, O-DU, O-CU). More generically, network node 1000 can be considered a type of network equipment. Base stations may be categorized based on the amount of coverage they provide (or, stated differently, their transmit power level) and so, depending on the provided amount of coverage, may be referred to as femto base stations, pico base stations, micro base stations, or macro base stations. A base station may be a relay node or a relay donor node controlling a relay. A network node may also include one or more (or all) parts of a distributed radio base station such as centralized digital units, distributed units (e.g., in an O-RAN access node) and / or remote radio units (RRUs), sometimes referred to as Remote Radio Heads (RRHs). Such remote radio units may or may not be integrated with an antenna as an antenna integrated radio. Parts of a distributed radio base station may also be referred to as nodes in a distributed antenna system (DAS).

[0211] Other examples of network nodes include multiple transmission point (multi-TRP) 5G access nodes, multi-standard radio (MSR) equipment such as MSR BSs, network controllers such as radio network controllers (RNCs) or base station controllers (BSCs), base transceiver stations (BTSs), transmission points, transmission nodes, multi-cell / multicast coordination entities (MCEs), Operation and Maintenance (O&M) nodes, Operations Support System (OSS) nodes, Self-Organizing Network (SON) nodes, positioning nodes (e.g., Evolved Serving Mobile Location Centers (E-SMLCs)), and / or Minimization of Drive Tests (MDTs).

[0212] Network node 1000 includes processing circuitry 1002, memory 1004, communication interface 1006, and power source 1008. Network node 1000 may be composed of multiple physically separate components (e.g., a NodeB component and a RNC component, or a BTS component and a BSC component, etc.), which may each have their own respective components. In certain scenarios in which network node 1000 comprises multiple separate components (e.g., BTS and BSC components), one or more of the separate components may be shared among several network nodes. For example, a single RNC may control multiple NodeBs. In such a scenario, each unique NodeB and RNC pair, may in some instances be considered a single separate network node. In some embodiments, network node 1000 may be configured to support multiple radio access technologies (RATs). In such embodiments, some components may be duplicated (e.g., separate memory 1004 for different RATs) and some components may be reused (e.g., a same antenna 1010 may be shared by different RATs). Network node 1000 may also include multiple sets of the various illustrated components for different wireless technologies integrated into network node 1000, for example GSM, WCDMA, LTE, NR, WiFi, Zigbee, Z-wave, LoRaWAN, Radio Frequency Identification (RFID) or Bluetooth wireless technologies. These wireless technologies may be integrated into the same or different chip or set of chips and other components within network node 1000.

[0213] Processing circuitry 1002 may comprise a combination of one or more of a microprocessor, controller, microcontroller, central processing unit, digital signal processor, application-specific integrated circuit, field programmable gate array, or any other suitable computing device, resource, or combination of hardware, software and / or encoded logic operable to provide, either alone or in conjunction with other network node 1000 components, such as memory 1004, to provide network node 1000 functionality.

[0214] In some embodiments, processing circuitry 1002 includes a system on a chip (SOC). In some embodiments, processing circuitry 1002 includes one or more of radio frequency (RF) transceiver circuitry 1012 and baseband processing circuitry 1014. In some embodiments, RF transceiver circuitry 1012 and baseband processing circuitry 1014 may be on separate chips (or sets of chips), boards, or units, such as radio units and digital units. In alternative embodiments, part or all of RF transceiver circuitry 1012 and baseband processing circuitry 1014 may be on the same chip or set of chips, boards, or units.

[0215] Memory 1004 may comprise any form of volatile or non-volatile computer-readable memory including, without limitation, persistent storage, solid-state memory, remotely mounted memory, magnetic media, optical media, random access memory (RAM), read-only memory (ROM), mass storage media (for example, a hard disk), removable storage media (for example, a flash drive, a Compact Disk (CD) or a Digital Video Disk (DVD)), and / or any other volatile or non-volatile, non-transitory device-readable and / or computer-executable memory devices that store information, data, and / or instructions that may be used by processing circuitry 1002. Memory 1004 may store any suitable instructions, data, or information, including a computer program, software, an application including one or more of logic, rules, code, tables, and / or other instructions (collected denoted computer program 1004a, which may be in the form of a computer program product) capable of being executed by processing circuitry 1002 and utilized by network node 1000. Memory 1004 may be used to store any calculations made by processing circuitry 1002 and / or any data received via communication interface 1006. In some embodiments, processing circuitry 1002 and memory 1004 is integrated.

[0216] Communication interface 1006 is used in wired or wireless communication of signaling and / or data between a network node, access network, and / or UE. As illustrated, communication interface 1006 comprises port(s) / terminal(s) 1016 to send and receive data, for example to and from a network over a wired connection. Communication interface 1006 also includes radio frontend circuitry 1018 that may be coupled to, or in certain embodiments a part of, antenna 1010. Radio front-end circuitry 1018 comprises filters 1020 and amplifiers 1022. Radio front-end circuitry 1018 may be connected to an antenna 1010 and processing circuitry 1002. The radio front-end circuitry may be configured to condition signals communicated between antenna 1010 and processing circuitry 1002. Radio front-end circuitry 1018 may receive digital data that is to be sent out to other network nodes or UEs via a wireless connection. Radio front-end circuitry 1018 may convert the digital data into a radio signal having the appropriate channel and bandwidth parameters using a combination of filters 1020 and / or amplifiers 1022. The radio signal may then be transmitted via antenna 1010. Similarly, when receiving data, antenna 1010 may collect radio signals which are then converted into digital data by radio front-end circuitry 1018. The digital data may be passed to processing circuitry 1002. In other embodiments, the communication interface may comprise different components and / or different combinations of components.

[0217] In certain alternative embodiments, network node 1000 does not include separate radio front-end circuitry 1018, instead, processing circuitry 1002 includes radio front-end circuitry and is connected to antenna 1010. Similarly, in some embodiments, all or some of RF transceiver circuitry 1012 is part of communication interface 1006. In still other embodiments, communication interface 1006 includes one or more ports or terminals 1016, radio front-end circuitry 1018, and RF transceiver circuitry 1012, as part of a radio unit (not shown), and communication interface 1006 communicates with baseband processing circuitry 1014, which is part of a digital unit (not shown).

[0218] Antenna 1010 may include one or more antennas, or antenna arrays, configured to send and / or receive wireless signals. Antenna 1010 may be coupled to radio front-end circuitry 1018 and may be any type of antenna capable of transmitting and receiving data and / or signals wirelessly. In certain embodiments, antenna 1010 is separate from network node 1000 and connectable to network node 1000 through an interface or port.

[0219] Antenna 1010, communication interface 1006, and / or processing circuitry 1002 may be configured to perform any receiving operations and / or certain obtaining operations described herein as being performed by the network node. Any information, data and / or signals may be received from a UE, another network node and / or any other network equipment. Similarly, antenna 1010, communication interface 1006, and / or processing circuitry 1002 may be configured to perform any transmitting operations described herein as being performed by the network node. Any information, data and / or signals may be transmitted to a UE, another network node and / or any other network equipment.

[0220] Power source 1008 provides power to the various components of network node 1000 in a form suitable for the respective components (e.g., at a voltage and current level needed for each respective component). Power source 1008 may further comprise, or be coupled to, power management circuitry to supply the components of network node 1000 with power for performing the functionality described herein. For example, network node 1000 may be connectable to an external power source (e.g., the power grid, an electricity outlet) via an input circuitry or interface such as an electrical cable, whereby the external power source supplies power to power circuitry of power source 1008. As a further example, power source 1008 may comprise a source of power in the form of a battery or battery pack which is connected to, or integrated in, power circuitry. The battery may provide backup power should the external power source fail.

[0221] Embodiments of network node 1000 may include additional components beyond those shown in Figure 10 for providing certain aspects of the network node’s functionality, including any of the functionality described herein and / or any functionality necessary to support the subject matter described herein. For example, network node 1000 may include user interface equipment to allow input of information into network node 1000 and to allow output of information from network node 1000. This may allow a user to perform diagnostic, maintenance, repair, and other administrative functions for network node 1000.

[0222] Figure 11 is a block diagram illustrating a virtualization environment 1100 in which functions implemented by some embodiments may be virtualized. More generically, virtualization environment 1100 can be considered a type of network equipment.

[0223] In the present context, virtualizing means creating virtual versions of apparatuses or devices which may include virtualizing hardware platforms, storage devices and networking resources. As used herein, virtualization can be applied to any device described herein, or components thereof, and relates to an implementation in which at least a portion of the functionality is implemented as one or more virtual components. Some or all of the functions described herein may be implemented as virtual components executed by one or more virtual machines (VMs) implemented in one or more virtual environments 1100 hosted by one or more of hardware nodes, such as a hardware computing device that operates as a network node, UE, core network node, or host. Further, in embodiments in which the virtual node does not require radio connectivity (e.g., a core network node or host), then the node may be entirely virtualized. In some embodiments, the virtualization environment 1100 includes components defined by the O-RAN Alliance, such as an O-Cloud environment orchestrated by a Service Management and Orchestration Framework via an O-2 interface.

[0224] Applications 1102 (which may alternatively be called software instances, virtual appliances, network functions, virtual nodes, virtual network functions, etc.) are run in the virtualization environment 1100 to implement some of the features, functions, and / or benefits of some of the embodiments disclosed herein.

[0225] Hardware 1104 includes processing circuitry, memory that stores software and / or instructions (collected denoted computer program 1104a, which may be in the form of a computer program product) executable by hardware processing circuitry, and / or other hardware devices as described herein, such as a network interface, input / output interface, and so forth. Software may be executed by the processing circuitry to instantiate one or more virtualization layers 1106 (also referred to as hypervisors or virtual machine monitors (VMMs)), provide VMs 1108a and 1108b (one or more of which may be generally referred to as VMs 1108), and / or perform any of the functions, features and / or benefits described in relation with some embodiments described herein. Virtualization layer 1106 may present a virtual operating platform that appears like networking hardware to the VMs 1108.

[0226] VMs 1108 comprise virtual processing, virtual memory, virtual networking or interface and virtual storage, and may be run by a corresponding virtualization layer 1106. Different embodiments of the instance of a virtual appliance 1102 may be implemented on one or more of VMs 1108, and the implementations may be made in different ways. Virtualization of the hardware is in some contexts referred to as network function virtualization (NFV). NFV may be used to consolidate many network equipment types onto industry standard high volume server hardware, physical switches, and physical storage, which can be located in data centers, and customer premise equipment.

[0227] In the context of NFV, each VM 1108 may be a software implementation of a physical machine that runs programs as if they were executing on a physical, non-virtualized machine. Each VM 1108, and that part of hardware 1104 that executes that VM, be it hardware dedicated to that VM and / or hardware shared by that VM with others of the VMs, forms separate virtual network elements. Still in the context of NFV, a virtual network function is responsible for handling specific network functions that run in one or more VMs 1108 on top of the hardware 1104 and corresponds to the application 1102.

[0228] Hardware 1104 may be implemented in a standalone network node with generic or specific components. Hardware 1104 may implement some functions via virtualization. Alternatively, hardware 1104 may be part of a larger cluster of hardware (e.g. such as in a data center or CPE) where many hardware nodes work together and are managed via management and orchestration function 1110, which, among others, oversees lifecycle management of applications 1102. In some embodiments, hardware 1104 is coupled to one or more radio units that each include one or more transmitters and one or more receivers that may be coupled to one or more antennas. Radio units may communicate directly with other hardware nodes via one or more appropriate network interfaces and may be used in combination with the virtual components to provide a virtual node with radio capabilities, such as a radio access node or a base station. In some embodiments, some signaling can be provided with the use of a control system 1112 which may alternatively be used for communication between hardware nodes and radio units.

[0229] Figure 12 shows a communication diagram of a host 1202 communicating via a network node 1204 with a UE 1206 over a partially wireless connection in accordance with some embodiments. Example implementations, in accordance with various embodiments, of the UE (such as a UE 912a of Figure 9), network node (such as network node 910a of Figure 9 and / or network node 1000 of Figure 10), and host (such as host 916 of Figure 9) discussed in the preceding paragraphs will now be described with reference to Figure 12.

[0230] Embodiments of host 1202 include hardware, such as a communication interface, processing circuitry, and memory. Host 1202 also includes software, which is stored in or accessible by host 1202 and executable by the processing circuitry. The software includes a host application that may be operable to provide a service to a remote user, such as UE 1206 connecting via an over-the-top (OTT) connection 1250 extending between UE 1206 and host 1202. In providing the service to the remote user, a host application may provide user data which is transmitted using OTT connection 1250.

[0231] Network node 1204 includes hardware enabling it to communicate with host 1202 and UE 1206. Connection 1260 may be direct or pass through a core network (like core network 906 of Figure 9) and / or one or more other intermediate networks, such as one or more public, private, or hosted networks. For example, an intermediate network may be a backbone network or the Internet.

[0232] UE 1206 includes hardware and software, which is stored in or accessible by UE 1206 and executable by the UE’s processing circuitry. The software includes a client application, such as a web browser or operator-specific “app” that may be operable to provide a service to a human or non-human user via UE 1206 with the support of host 1202. In host 1202, an executing host application may communicate with the executing client application via OTT connection 1250 terminating at UE 1206 and host 1202. In providing the service to the user, the UE’s client application may receive request data from the host's host application and provide user data in response to the request data. OTT connection 1250 may transfer both the request data and the user data. The UE’s client application may interact with the user to generate the user data that it provides to the host application through OTT connection 1250.

[0233] OTT connection 1250 may extend via a connection 1260 between host 1202 and network node 1204 and via a wireless connection 1270 between network node 1204 and UE 1206 to provide the connection between host 1202 and UE 1206. Connection 1260 and wireless connection 1270, over which OTT connection 1250 may be provided, have been drawn abstractly to illustrate the communication between host 1202 and UE 1206 via network node 1204, without explicit reference to any intermediary devices and the precise routing of messages via these devices.

[0234] As an example of transmitting data via OTT connection 1250, in step 1208, host 1202 provides user data, which may be performed by executing a host application. In some embodiments, the user data is associated with a particular human user interacting with UE 1206. In other embodiments, the user data is associated with a UE 1206 that shares data with host 1202 without explicit human interaction. In step 1210, host 1202 initiates a transmission carrying the user data towards UE 1206. Host 1202 may initiate the transmission responsive to a request transmitted by UE 1206. The request may be caused by human interaction with UE 1206 or by operation of the client application executing on UE 1206. The transmission may pass via network node 1204, in accordance with the teachings of the embodiments described throughout this disclosure. Accordingly, in step 1212, network node 1204 transmits to UE 1206 the user data that was carried in the transmission that host 1202 initiated, in accordance with the teachings of the embodiments described throughout this disclosure. In step 1214, UE 1206 receives the user data carried in the transmission, which may be performed by a client application executed on UE 1206 associated with the host application executed by host 1202.

[0235] In some examples, UE 1206 executes a client application which provides user data to host 1202. The user data may be provided in reaction or response to the data received from host 1202. Accordingly, in step 1216, UE 1206 may provide user data, which may be performed by executing the client application. In providing the user data, the client application may further consider user input received from the user via an input / output interface of UE 1206. Regardless of the specific manner in which the user data was provided, UE 1206 initiates, in step 1218, transmission of the user data towards host 1202 via network node 1204. In step 1220, in accordance with the teachings of the embodiments described throughout this disclosure, network node 1204 receives user data from UE 1206 and initiates transmission of the received user data towards host 1202. In step 1222, host 1202 receives the user data carried in the transmission initiated by UE 1206.

[0236] One or more of the various embodiments improve the performance of OTT services provided to UE 1206 using OTT connection 1250, in which wireless connection 1270 forms the last segment. More precisely, may provide advantages of both CP and in-band signaling techniques for UP path switch without some or all of the problems, issues, and / or difficulties of the two techniques. For example, embodiments can facilitate fast handover and low CP load due to the use of in-band signaling while retaining the versatility of CP decision making about UPF allocation and placement due UPF notification about a path switch. As another example, embodiments can facilitate fast handover and low CP load due to the use of in-band signaling as default while retaining the versatility of CP decision making for exceptional cases. Embodiments may be particularly advantageous when RAN CP is more centralized than the RAN UP, which may be the situation for future cloud-based RAN deployments. By improving network operation in this manner, embodiments increase the value to both end users and service providers of OTT services delivered via the improved network.

[0237] In an example scenario, factory status information may be collected and analyzed by host 1202. As another example, host 1202 may process audio and video data which may have been retrieved from a UE for use in creating maps. As another example, host 1202 may collect and analyze real-time data to assist in controlling vehicle congestion (e.g., controlling traffic lights). As another example, host 1202 may store surveillance video uploaded by a UE. As another example, host 1202 may store or control access to media content such as video, audio, VR or AR which it can broadcast, multicast or unicast to UEs. As other examples, host 1202 may be used for energy pricing, remote control of non-time critical electrical load to balance power generation needs, location services, presentation services (such as compiling diagrams etc. from data collected from remote devices), or any other function of collecting, retrieving, storing, analyzing and / or transmitting data.

[0238] In some examples, a measurement procedure may be provided for the purpose of monitoring data rate, latency and other factors on which the one or more embodiments improve. There may further be an optional network functionality for reconfiguring OTT connection 1250 between host 1202 and UE 1206, in response to variations in the measurement results. The measurement procedure and / or the network functionality for reconfiguring the OTT connection may be implemented in software and hardware of host 1202 and / or UE 1206. In some embodiments, sensors (not shown) may be deployed in or in association with other devices through which OTT connection 1250 passes; the sensors may participate in the measurement procedure by supplying values of the monitored quantities exemplified above, or supplying values of other physical quantities from which software may compute or estimate the monitored quantities. The reconfiguring of OTT connection 1250 may include message format, retransmission settings, preferred routing etc.; the reconfiguring need not directly alter the operation of network node 1204. Such procedures and functionalities may be known and practiced in the art. In certain embodiments, measurements may involve proprietary UE signaling that facilitates measurements of throughput, propagation times, latency, and the like, by host 1202. The measurements may be implemented in that software causes messages to be transmitted, in particular empty or ‘dummy’ messages, using OTT connection 1250 while monitoring propagation times, errors, etc.

[0239] The foregoing merely illustrates the principles of the disclosure. Various modifications and alterations to the described embodiments will be apparent to those skilled in the art in view of the teachings herein. It will thus be appreciated that those skilled in the art will be able to devise numerous systems, arrangements, and procedures that, although not explicitly shown or described herein, embody the principles of the disclosure and can be thus within the spirit and scope of the disclosure. Various embodiments can be used together with one another, as well as interchangeably therewith, as should be understood by those having ordinary skill in the art. The term unit, as used herein, can have conventional meaning in the field of electronics, electrical devices and / or electronic devices and can include, for example, electrical and / or electronic circuitry, devices, modules, processors, memories, logic solid state and / or discrete devices, computer programs or instructions for carrying out respective tasks, procedures, computations, outputs, and / or displaying functions, and so on, as such as those that are described herein.

[0240] Any appropriate steps, methods, features, functions, or benefits disclosed herein may be performed through one or more functional units or modules of one or more virtual apparatuses. Each virtual apparatus may comprise a number of these functional units. These functional units may be implemented via processing circuitry, which may include one or more microprocessor or microcontrollers, as well as other digital hardware, which may include Digital Signal Processor (DSPs), special-purpose digital logic, and the like. The processing circuitry may be configured to execute program code stored in memory, which may include one or several types of memory such as Read Only Memory (ROM), Random Access Memory (RAM), cache memory, flash memory devices, optical storage devices, etc. Program code stored in memory includes program instructions for executing one or more telecommunications and / or data communications protocols as well as instructions for carrying out one or more of the techniques described herein. In some implementations, the processing circuitry may be used to cause the respective functional unit to perform corresponding functions according to one or more embodiments of the present disclosure.

[0241] As described herein, device and / or apparatus can be represented by a semiconductor chip, a chipset, or a (hardware) module comprising such chip or chipset; this, however, does not exclude the possibility that a functionality of a device or apparatus, instead of being hardware implemented, be implemented as a software module such as a computer program or a computer program product comprising executable software code portions for execution or being run on a processor. Furthermore, functionality of a device or apparatus can be implemented by any combination of hardware and software. A device or apparatus can also be regarded as an assembly of multiple devices and / or apparatuses, whether functionally in cooperation with or independently of each other. Moreover, devices and apparatuses can be implemented in a distributed fashion throughout a system, so long as the functionality of the device or apparatus is preserved. Such and similar principles are considered as known to a skilled person.

[0242] Furthermore, functions described herein as being performed by a wireless device or a network node may be distributed over a plurality of wireless devices and / or network nodes. In other words, it is contemplated that the functions of a network node and a wireless device described herein are not limited to performance by a single physical device and, in fact, can be distributed among several physical devices. Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. It will be further understood that terms used herein should be interpreted as having a meaning that is consistent with their meaning in the context of this specification and the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0243] In addition, certain terms used in the present disclosure, including the specification and drawings, can be used synonymously in certain instances (e.g., “data” and “information”). It should be understood, that although these terms (and / or other terms that can be synonymous to one another) can be used synonymously herein, there can be instances when such words can be intended to not be used synonymously.

Claims

CLAIMS1. A method for a radio access network, RAN, control plane, CP, entity configured for selective user plane, UP, path switch signaling, the method comprising: determining (720) that a path switch is needed for one or more user equipment, UE, protocol data unit, PDU, sessions with a user plane function, UPF, in a core network, CN, coupled to the RAN, wherein the path switch is from a first path that includes a source RAN UP entity to a second path that includes a target RAN UP entity; evaluating (730) one or more policy rules related to path switch procedures; and selectively performing (740) an in-band path switch procedure or a CP path switch procedure for the UE, based on a result of the evaluation.

2. The method of claim 1, wherein evaluating (730) the one or more policy rules is based on one or more conditions related to one or more of the following: the UE, the RAN CP entity, the target RAN UP entity, and the UPF.

3. The method of claim 2, wherein the one or more conditions include one or more of the following: whether a different RAN CP entity is needed in conjunction with the path switch; whether all of the UE’s existing quality-of-service, QoS, flows can be supported by the target RAN UP entity; whether the target RAN UP entity supports different features than the source RAN UP entity; whether the UPF is reachable by the target RAN UP entity; transport latency from the target RAN UP entity to the UPF; and area assignments of the target RAN UP entity and the UPF.

4. The method of claim 3, wherein the one or more policy rules include one or more compatibility rules for the area assignments of the target RAN UP entity and the UPF.

5. The method of any of claims 2-4, wherein selectively performing (740) an in-band path switch procedure or a CP path switch procedure for the UE, based on a result of the evaluation, comprises:performing (741) a CP path switch procedure when the evaluation indicates that the one or more conditions meet at least one of the policy rules; and performing (742) an in-band path switch procedure when the evaluation indicates that the one or more conditions do not meet at least one of the policy rules.

6. The method of claim 6, wherein performing a CP path switch procedure comprises: sending a Path Switch Request message to an access and mobility management function, AMF, in the CN; and receiving a Path Switch Response message from the AMF.

7. The method of claim 6, wherein one of the following applies: the path switch is related to a handover of the UE and Path Switch Request message is an N2 PATH SWITCH REQUEST message; or the path switch is related to a PDU session modification for the UE and the Path Switch Request message is a PDU Session Modification Request message.

8. The method of any of claims 5-7, wherein the CP path switch procedure is performed based on one or more of the following results of the evaluation: a different RAN CP entity is needed in conjunction with the path switch; one or more of the UE’s existing QoS flows cannot be supported by the target RAN UP entity. the UPF is unreachable by the target RAN UP entity. the transport latency from the target RAN UP to the UPF is greater than a maximum allowed latency. the transport latency from the target RAN UP to the UPF is unknown; the area assignments of the target RAN UP entity and the UPF are incompatible; and the target RAN UP entity supports different features than the source RAN UP entity, which requires feature enablement in the CN CP.

9. The method of any of claims 5-8, wherein performing an in-band path switch procedure comprises sending a Path Switch Command message to the target RAN UP entity.

10. The method of claim 9, wherein the Path Switch Command message includes one or more of the following:an indication that the target RAN UP entity should request the UPF to notify the CN CP about the path switch for the UE; a list of the UE’s PDU sessions that failed to setup in the target RAN UP entity; a list of the UE’s existing quality-of-service (QoS) flows that cannot be supported in the target RAN UP entity; a list of supported features; and an indication that the UE will be located in a different network area due to the path switch.

11. The method of any of claims 9-10, wherein: the RAN CP entity is a centralized unit CP, CU-CP, of a RAN node; the target RAN UP entity is a centralized unit UP, CU-UP, of the RAN node; and the Path Switch Command message is, or is included in, a message on an El interface between the CU-CP and the CU-UP.

12. The method of claim 11, wherein one or more of the following applies: the CU-CP is remote from the CU-UP, and the CU-CP is hosted by cloud computing environment.

13. The method of any of claims 1-12, wherein one of the following applies: the policy rules are predefined; or the method further comprises receiving (710) the policy rules from one of the following: an operations / administration / maintenance, 0AM, system coupled to the RAN, wherein the received policy rules are applicable to all UEs and PDU sessions; or a network function of the CN, wherein the received policy rules are specific to one or more of the following: the UE, or each of the UE’s PDU sessions with the UPF.

14. A method for a user plane function, UPF, of a core network, CN, coupled to a radio access network, RAN, the method comprising: receiving (820) an in-band Path Switch Request message indicating a path switch for one or more user equipment, UE, protocol data unit, PDU, sessions with the UPF, wherein:the path switch is from a first path that includes a source RAN user plane, UP, entity to a second path that includes a target RAN UP entity; and the in-band Path Switch Request message is received from the target RAN UP entity; evaluating (830) one or more policy rules related to path switch procedures; and selectively notifying (840) one or more network functions, NFs, of the CN CP about the path switch for the UE PDU sessions with the UPF, based on a result of the evaluation.

15. The method of claim 14, wherein evaluating the one or more policy rules is based on one or more of the following inputs: an identity of the UE; a downlink, DL, data address in target RAN UP entity; transport latency from the UPF to the target RAN UP entity; and one or more information elements, IES, of the in-band Path Switch Request message.

16. The method of claim 15, wherein the one or more IEs include one or more of the following: an indication that the UPF should notify the CN CP about the path switch; a list of the UE’s PDU sessions that failed to setup in the target RAN UP entity, a list of the UE’s existing quality-of-service, QoS, flows that are not supported by the target RAN UP entity, a list of features supported by the target RAN UP entity; an indication that the target RAN UP entity is assigned to a different area than the source RAN UP entity; and an area assignment of the target RAN UP entity.

17. The method of claim 16, wherein the one or more policy rules include one or more compatibility rules for the area assignments of the target RAN UP entity and the UPF.

18. The method of any of claims 15-17, wherein selectively notifying (840) the one or more NFs of the CN CP about the path switch based on a result of the evaluation comprises: notifying (841) the one or more NFs of the CN CP when the evaluation indicates that the one or more inputs meet at least one of the policy rules; andrefraining from notifying (842) the one or more NFs of the CN CP when the evaluation indicates that the one or more inputs do not meet at least one of the policy rules.

19. The method of claim 18, wherein notifying (841) the one or more NFs of the CN CP comprises sending an N4 Session Modification Notify message to a session management function, SMF, of the CN CP.

20. The method of claim 19, wherein the N4 Session Modification Notify includes an explicit or implicit indication for the SMF to notify an access and mobility management function, AMF, of the CN CP about the path switch.

21. The method of any of claims 15-20, wherein the one or more NFs of the CN CP are notified based on one or more of the following results of the evaluation: the in-band Path Switch Request messages includes an indication that the UPF should notify the CN CP about the path switch; and the DL data address in the target RAN UP entity is not reachable by the UPF; the transport latency from the UPF to the target RAN UP entity is greater than a maximum allowed latency; and the transport latency from the UPF to the target RAN UP entity is unknown.

22. The method of any of claims 15-21, wherein the one or more NFs of the CN CP are notified when evaluation of the one or more policy rules based on the one or more IES in the in-band Path Switch Request message indicates one or more of the following: one or more of the UE’s PDU sessions failed to setup in the target RAN UP entity; one or more of the UE’s existing QoS flows are not supported by the target RAN UP entity; the target RAN UP entity supports one or more features that require feature enablement in the CN CP; and the area assignments of the target RAN UP entity and the UPF are incompatible.

23. The method of any of claims 14-22, wherein one of the following applies: the policy rules are predefined; or the method further comprises receiving (810) the policy rules from one of the following:an operations / administration / maintenance, OAM, system coupled to the CN, wherein the received policy rules are applicable to all UEs and PDU sessions; or a session management function, SMF, of the CN CP, wherein the received policy rules are specific to one or more of the following: the UPF, or each of the UE’s PDU sessions with the UPF.

24. The method of any of claims 14-23, wherein the path switch is associated with one of the following procedures for the UE: handover from a source cell served by the source RAN UP entity to a target cell served by the target RAN UP entity, or PDU session modification.

25. Network equipment (910, 1000, 1100) arranged to implement a radio access network, RAN, control plane, CP, entity (210, 623, 1102) configured for selective user plane, UP, path switch signaling, the network equipment comprising: communication interface circuitry (1006, 1104) configured to communicate with one or more RAN UP entities (621, 622) and with one or more network functions, NFs (630, 650) of a core network, CN (198, 906) coupled to the RAN (199, 620, 904); and processing circuitry (1002, 1104) operably coupled to the communication interface circuitry, wherein the processing circuitry and communication interface circuitry are configured to: determine that a path switch is needed for one or more user equipment, UE (610), protocol data unit, PDU, sessions with a user plane function, UPF (650) in the CN, wherein the path switch is from a first path that includes a source RAN UP entity (621) to a second path that includes a target RAN UP entity (622); evaluate one or more policy rules related to path switch procedures; and selectively perform an in-band path switch procedure or a CP path switch procedure for the UE, based on a result of the evaluation.

25. The network equipment of claim 24, wherein the processing circuitry and communication interface circuitry are further configured to perform operations corresponding to any of the methods of claims 2-13.

26. Network equipment (910, 1000, 1100) arranged to implement a radio access network, RAN, control plane, CP, entity (210, 623, 1102) configured for selective user plane, UP, path switch signaling, the network equipment being configured to: determine that a path switch is needed for one or more user equipment, UE (610), protocol data unit, PDU, sessions with a user plane function, UPF (650) in a core network, CN (198, 906) coupled to the RAN (199, 620, 904), wherein the path switch is from a first path that includes a source RAN UP (621) entity to a second path that includes a target RAN UP entity (622); evaluate one or more policy rules related to path switch procedures; and selectively perform an in-band path switch procedure or a CP path switch procedure for the UE, based on a result of the evaluation.

27. The network equipment of claim 26, being further configured to perform operations corresponding to any of the methods of claims 2-13.

28. A non-transitory, computer-readable medium (1004, 1104) storing computer-executable instructions that, when executed by processing circuitry (1002, 1104) associated with a radio access network, RAN, control plane, CP, entity (210, 623, 1102) configured for selective user plane, UP, path switch signaling, configure the RAN CP entity to perform operations corresponding to any of the methods of claims 1-13.

29. A computer program product (1004a, 1104a) comprising computer-executable instructions that, when executed by processing circuitry (1002, 1104) associated with a radio access network, RAN, control plane, CP, entity (210, 623, 1102) configured for selective user plane, UP, path switch signaling, configure the RAN CP entity to perform operations corresponding to any of the methods of claims 1-13.

30. Network equipment (908, 1000, 1100) configured to implement a user plane function, UPF (650) of a core network, CN (198, 906) coupled to a radio access network, RAN (199, 620, 904), the network equipment comprising: communication interface circuitry (1006, 1104) configured to communicate with one or more RAN user plane, UP, entities (621, 622) and with one or more network functions, NFs (640) of a control plane of the CN; andprocessing circuitry (1002, 1104) operably coupled to the communication interface circuitry, whereby the processing circuitry and the communication interface circuitry are configured to: receive an in-band Path Switch Request message indicating a path switch for one or more user equipment, UE (610) protocol data unit, PDU, sessions with the UPF, wherein: the path switch is from a first path that includes a source RAN user plane, UP, entity (621) to a second path that includes a target RAN UP entity (622); and the in-band Path Switch Request message is received from the target RAN UP entity; evaluate one or more policy rules related to path switch procedures; and selectively notify one or more network functions, NFs (630, 640) of the CN CP about the path switch for the UE PDU sessions with the UPF, based on a result of the evaluation.

31. The network equipment of claim 30, wherein the processing circuitry and the communication interface circuitry are further configured to perform operations corresponding to any of the methods of claims 15-24.

32. Network equipment (908, 1000, 1100) configured to implement a user plane function, UPF (650) of a core network, CN (198, 906) coupled to a radio access network, RAN (199, 620, 904), the network equipment being further configured to: receive an in-band Path Switch Request message indicating a path switch for one or more user equipment, UE (610) protocol data unit, PDU, sessions with the UPF, wherein: the path switch is from a first path that includes a source RAN user plane, UP, entity (621) to a second path that includes a target RAN UP entity (622); and the in-band Path Switch Request message is received from the target RAN UP entity; evaluate one or more policy rules related to path switch procedures; and selectively notify one or more network functions, NFs (630, 640) of the CN CP about the path switch for the UE PDU sessions with the UPF, based on a result of the evaluation.

33. The network equipment of claim 32, being further configured to perform operations corresponding to any of the methods of claims 15-24.

34. A non-transitory, computer-readable medium (1004, 1104) storing computer-executable instructions that, when executed by processing circuitry (1002, 1104) associated with a user plane function, UPF (650) of a core network, CN (198, 906) coupled to a radio access network, RAN (199, 620, 904), configure the UPF to perform operations corresponding to any of the methods of claims 14-24.

35. A computer program product (1004a, 1104a) comprising computer-executable instructions that, when executed by processing circuitry (1002, 1104) associated with a user plane function, UPF (650) of a core network, CN (198, 906) coupled to a radio access network, RAN (199, 620, 904), configure the UPF to perform operations corresponding to any of the methods of claims 14-24.

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