SUSPEND AND EARL Y RRC RELEASE

Related Applications

[0001] This application claims the benefit of provisional patent application serial number 62/862,868, filed June 18, 2019, the disclosure of which is hereby incorporated herein by reference in its entirety.

Technical Field

[0002] The present disclosure relates to a cellular communications system and, in particular, to network-initiated connection suspend and to early connection release in a cellular communications system.

Background

[0003] Third Generation Partnership Project (3GPP) Fifth Generation (5G) System (5GS) Release (Rel-) 16 specifies Cellular Internet of Things (CIoT) related functionality, User Plane (UP) CIoT 5GS Optimization in Technical Specification (TS) 23.501, Version 16.1.0, clause 5.31.18 and TS 23.502, Version 16.1.1, clauses 4.8.1.2 and 4.8.2.3.

Connection Suspend

[0004] TS 23.501, clause 5.31.18 states that User Plane CIoT 5GS Optimization enables transfer of user plane data from CM-IDLE without the need for using the Service Request procedure to establish Access Stratum (AS) context in Next Generation Radio Access Network (NG-RAN) and User Equipment (UE).

[0005] The Radio Resource Control (RRC) connection can be suspended by means of the Connection Suspend Procedure if the following preconditions are met:

The UE and the Access and Mobility Management Function (AMF) have negotiated support for User Plane CIoT 5GS Optimization (TS 23.501, clause 5.31.2) over Non-Access Stratum (NAS);

The UE has indicated support of User Plane CIoT 5GS Optimization in the UE radio capabilities as defined in 3GPP TS 36.331 (see, e.g., V15.5.1);

The AMF has indicated User Plane CIoT 5GS Optimization support to the NG- RAN; and The UE has established at least one Protocol Data Unit (PDU) session with an active User Plane (UP) connection, i.e., the AS context is established in the NG-RAN and the UE.

[0006] By using the Connection Suspend Procedure, when the UE transitions into CM-IDLE, the UE stores the AS information; the NG-RAN stores the AS information, the Next Generation Application Protocol (NGAP) UE association, and the PDU session context for that UE; and the AMF stores the NGAP UE association and other information necessary to later resume the UE, interacts with the Session Management Function(s) (SMF(s)) to deactivate the user plane resources for the UE's PDU Sessions, and enters the CM-IDLE state.

[0007] The NG-RAN may decide based on implementation to delete the stored UE context and NGAP association. In that case, the NG-RAN initiates the Access Network (AN) Release procedure as described in clause 4.2.6 of TS 23.502. The NG-RAN does not initiate any RRC procedure to notify the UE of the UE context release.

[0008] Figure 1 illustrates a conventional NG-RAN initiated Connection Suspend procedure. This procedure may be initiated by the serving NG-RAN node when the UE is in the CM-CONNECTED state and has at least one PDU session with active user plane connection, and Next Generation evolved or enhanced Node B (NG-eNB) has received indication from the AMF that User Plane CIoT 5GS Optimization, as defined in TS 23.501 clause 5.31.18, is supported for the UE.

[0009] The conventional Connection Suspend procedure includes the following steps:

[0010] Step 100. NG-RAN to AMF: The NG-RAN sends the N2 Suspend Request message to the AMF, see TS 38.413. The AMF enters CM-IDLE with Suspend indicator. Context information related to the NGAP UE association, UE Context, and PDU session context necessary to resume the connection is stored in the UE, the NG-RAN node, and the AMF. The NG-RAN may include the Suspend cause and the N2 Session

Management (SM) information.

[0011] The NG-RAN may include the Information On Recommended Cells And NG- RAN For Paging in the N2 Suspend Request message. If available, the AMF stores this information to be used when paging the UE. The NG-RAN includes Information for Enhanced Coverage, if available, in the N2 Suspend Request message. If Service Gap Control is being applied to the UE (see clause 4.3.17.9 of TS 23.501) and the Service Gap timer is not already running, the Service Gap timer is started in the AMF when entering CM-IDLE, unless the connection was initiated after a paging of an mobile terminating (MT) event, or after a mobility registration procedure without Follow-on Request indication.

[0012] Step 102. AMF to SMF: For each of the PDU Sessions in the N2 Suspend Request, the AMF invokes Nsmf_PDUSession_UpdateSMContext Request (PDU Session ID, Cause, Operation type, User Location Information, Age of Location Information, N2 SM Information (Secondary RAT usage data)). The Operation Type is set to "UP Suspend" to indicate suspend of user plane resources for the PDU Session.

[0013] Step 104. SMF to UPF: The SMF sends the N4 Session Modification

Request (AN Tunnel Info to be suspended, Buffering on/off) to the User Plane Function (UPF). In this manner, the SMF initiates an N4 Session Modification procedure indicating the need to release the tunnel info of AN or UPF terminating N3. Buffering on/off indicates whether the UPF is to buffer incoming downlink (DL) PDU or not. The UPF sends N4 Session Modification Response to acknowledge the SMF request.

[0014] Step 106. SMF to AMF: The SMF sends

Nsmf_PDUSession_UpdateSMContext response to the AMF.

[0015] Step 108. AMF to NG-RAN : After response for each PDU session in step 106, the AMF sends N2 Suspend Response to NG-RAN to successfully terminate the Connection Suspend procedure initiated by the NG-RAN, see 3GPP TS 38.413.

[0016] Step 110. The NG-RAN sends an RRC message to suspend the RRC Connection towards the UE including UE Resume ID, see TS 36.300. If Service Gap Control is applied for the UE (see TS 23.501 clause 5.31.16) and the Service Gap timer is not already running, the Service Gap timer is started in the UE when entering CM- IDLE, unless the connection was initiated as a response to paging of an MT event, or after a mobility registration procedure without Follow-on Request Indication set.

Connection Resume

[0017] Based on a trigger from the Non-Access Stratum (NAS) layer when a UE is in CM-IDLE with Suspend, the UE should attempt the Connection Resume in CM-IDLE with Suspend procedure (clause 4.8.2.3 of TS 23.502). If the Connection Resume in CM- IDLE with Suspend procedure fails, the UE initiates the pending NAS procedure. To maintain support for User Plane CIoT 5GS Optimization for UE mobility across different NG-RAN nodes, the AS Context should be transferred between the NG-RAN nodes, see TS 38.300 and TS 38.423.

[0018] By using the Connection Resume in CM-IDLE with Suspend procedure:

The UE resumes the connection from CM-IDLE with the network using the AS information stored during the Connection Suspend procedure; and The NG-RAN node notifies the AMF that the connection with the UE has been resumed, and the AMF enters CM-CONNECTED and interacts with the SMF to activate the user plane resources for the UE's PDU Sessions.

[0019] The UE may include early uplink data in the Connection Resume. If the AMF establishes an NGAP UE association with a new NG-RAN node different from the stored NGAP UE association, e.g., the UE initiates service request or registration procedure from a different NG-RAN node, the AMF initiates UE N2 release command towards the old NG-RAN node.

[0020] The NG-RAN maintains the N3 tunnel endpoint information while a UE is in CM-IDLE with Suspend. The UPF is instructed to remove DL N3 Tunnel Info of AN during Connection Suspend procedure, while the UPF keeps UL N3 Tunnel Info (i.e., UPF accepts and forwards UL data).

[0021] Figure 2 illustrates a conventional Connection Resume in CM-IDLE with Suspend procedure. For the UE supporting User Plane CIoT 5GS Optimization, the Connection Resume procedure is used by the UE to perform RRC_IDLE with Suspend to RRC_CONNECTED state transition. Triggers for the UE to initiate this procedure are defined in TS 23.501, clause 5.31.18.

[0022] The conventional Connection Resume in CM-IDLE with Suspend procedure includes the following steps:

[0023] Step 200. UE to NG-RAN: The UE sends an RRC message (Resume ID) to the NG-RAN. In this manner, the UE initiates the transition from CM-IDLE and RRC IDLE state with Suspend to CM-CONNECTED and RRC Connected state, see TS 36.300. The UE provides its Resume ID needed by the NG-RAN to access the UE's stored Context.

[0024] Step 202. [Conditional] The NG-RAN performs UE Context Retrieval. UE Context Retrieval may be performed when the UE Context associated with the UE attempting to resume its connection is not locally available at the accessed NG-RAN node. The UE Context Retrieval procedure via radio access network is specified in TS 38.300.

[0025] Step 204. The NG-RAN and UE continue the resume procedure, and access stratum configuration synchronization is performed between the UE and the network. The UE enters CM-CONNECTED and RRC_CONNECTED.

[0026] Step 206. NG-RAN to AMF: a) If the NG-RAN node is the same as the NG- RAN node when UE was suspended, the NG-RAN node sends N2 Resume Request to the AMF including Resume cause and N2 SM information which indicates the PDU sessions successfully resumed and PDU sessions failed or partially failed to resume the user plane resource; b) If the NG-RAN node is different from the NG-RAN node when UE is suspended, and the new NG-RAN node is able to retrieve the UE Context from the old NG-RAN node, the new NG-RAN node initiates N2 Path Switch Request towards the AMF, i.e., Steps lb of TS 23.502, clause 4.9.I.2.2.

[0027] Step 208. AMF to SMF: For each of the PDU Sessions indicated in step 206, the AMF invokes Nsmf_PDUSession_UpdateSMContext Request (PDU Session ID, Cause, Operation type, User Location Information, Age of Location Information, N2 SM Information). The Operation Type is set to "UP Resume" to indicate resume of user plane resources for the PDU Session. For PDU Session(s) to be switched to the new NG-RAN node, upon receipt of the Nsmf_PDUSession_UpdateSMContext request, the SMF determines whether the existing UPF can continue to serve the UE. If the existing UPF cannot continue to serve the UE, steps 3 to 7 of TS 23.502, clause 4.9.1.2.3 or TS 23.502, clause 4.9.1.2.4 are performed depending on whether the existing UPF is a PDU Session Anchor and flow continues in step 212. Otherwise, step 210 is performed if the existing UPF can continue to serve the PDU Session.

[0028] Step 210. SMF to UPF: N4 Session Modification Request (AN Tunnel Info to be resumed, Buffering on/off). The SMF initiates an N4 Session Modification procedure indicating the resume of AN tunnel. Buffering on/off indicates whether the UPF shall buffer incoming DL PDU or not. The UPF sends N4 Session Modification Response to acknowledge the SMF request.

[0029] Step 212. SMF to AMF: The SMF sends

Nsmf_PDUSession_UpdateSMContext response to the AMF. If new CN tunnel information is allocated for the PDU session, the SMF includes the new CN tunnel information as part of the N2 SM information. If the resume for PDU session is unsuccessful, the SMF shall include the resume failure as part of the N2 SM information.

[0030] Step 214. AMF to NG-RAN: After response for each PDU session in step 212, the AMF sends N2 Resume Response to NG-RAN and indicates success, including N2 SM information for PDU session received in step 212, if at least one PDU session is resumed successfully. If none of the PDU sessions is resumed successfully, AMF indicates failure to NG-RAN. The AMF sends N2 Path Switch Acknowledge with PDU session resume information, if Path Switch Request is received in step 206. The AMF may provide Extended Connected Time value to the NG-RAN. If the NG-RAN receives the Extended Connected Time value, the NG-RAN may take this information into account when determining user inactivity.

[0031] Step 216. [Conditional] NG-RAN to UE: RRC message. The NG-RAN may reconfigure the RRC connection based on resume result received from AMF.

Expected UE Behavior Parameters

[0032] The following Expected UE Behavior parameters characterize the foreseen behavior of a UE or a group of UEs. Sets of these parameters may be provided via the Network Exposure Function (NEF) to be stored as part of the subscriber data. Each parameter within the Expected UE Behavior has an associating validity time. The validity time indicates when the Expected UE Behavior parameter expires and is deleted by the related Network Functions (NFs). The validity time may be set to indicate that the particular Expected UE Behavior parameter has no expiration time. When the validity time expires, the related NFs delete their local copy of the associated Expected UE Behavior parameter(s). The provision procedure of the Expected UE Behavior is realized by external parameter provision procedure defined in TS 23.502,

clause 4.15.6.2. Table 1- Expected UE Behavior Parameters

[0033] The Expected UE Moving Trajectory may be used by the AMF. All other parameters may be used by the AMF and by the SMF. The Scheduled Communication Type and the Traffic Profile should not be used by the AMF to release the UE when NAS Release Assistance Indication from the UE is available.

Summary

[0034] Systems and methods for network-initiated connection resume and early Radio Resource Control (RRC) release are disclosed. Embodiments of a method performed by a Radio Access Network (RAN) node are disclosed. In one embodiment, a method performed by a RAN node for RAN-initiated suspension of a connection of a User Equipment (UE) comprises determining whether there is pending Mobile

Terminated (MT) data or MT signaling associated with a UE. The method further comprises sending or refraining from sending a suspend request to an Access and Mobility Management Function (AMF) associated with the UE in accordance with a result of the determining whether there is pending MT data or MT signaling associated with the UE. In this manner, the connection is suspended if there is no pending MT data or MT signaling associated with the UE; otherwise, the connection is not suspended.

[0035] In one embodiment, sending or refraining from sending the suspend request comprises sending the suspend request to the AMF associated with the UE if there is no pending MT data or MT signaling associated with the UE, and refraining from sending the suspend request to the AMF associated with the UE if there is pending MT data or MT signaling associated with the UE.

[0036] In one embodiment, sending or refraining from sending the suspend request comprises sending the suspend request to the AMF associated with the UE only if there is no pending MT data or MT signaling associated with the UE.

[0037] In one embodiment, determining whether there is pending MT data or MT signaling associated with the UE comprises determining whether there is pending MT data or MT signaling associated with the UE based on whether a UE context of the UE comprises an indicator that there is pending MT data or MT signaling associated with the UE.

[0038] Corresponding embodiments of a RAN node are also disclosed. In one embodiment, a RAN node for RAN-initiated suspension of a UE is adapted to determine whether there is pending MT data or MT signaling associated with a UE and send or refrain from sending a suspend request to an AMF associated with the UE in accordance with a result of the determining whether there is pending MT data or MT signaling associated with the UE.

[0039] In one embodiment, a RAN node for RAN-initiated suspension of a UE comprising processing circuitry configured to cause the RAN node to determine whether there is pending MT data or MT signaling associated with a UE and send or refrain from sending a suspend request to an AMF associated with the UE in accordance with a result of the determining whether there is pending MT data or MT signaling associated with the UE.

[0040] In another embodiment, a method performed by a RAN node for early RRC release comprises receiving, from a UE, a resume request comprising a resume identity of the UE, where the resume request initiates a resume procedure. The method further comprises receiving, from the UE, Access Stratum (AS) release assistance information together with either the resume request or uplink data transmitted by the UE in association with the resume request and determining , based on the AS release assistance information, to perform early RRC release of the UE.

[0041] In one embodiment, the AS release assistance information comprises information about a traffic pattern of the UE.

[0042] In one embodiment, the AS release assistance information comprises an indication that there is pending MT data or signaling associated with the UE.

[0043] In one embodiment, determining to perform early RRC release comprises determining to perform early RRC release directly after an uplink data transmission transmitted by the UE during the resume procedure is complete.

[0044] In one embodiment, wherein determining to perform early RRC release comprises determining to perform early RRC release based on the AS release assistance information and an expected UE behavior parameter stored in a UE context of the UE stored by the RAN node. In one embodiment, the expected UE behavior parameter comprises a traffic pattern parameter.

[0045] Corresponding embodiments of a RAN node are also disclosed. In one embodiment, a RAN node for early RRC release is adapted to receive, from a UE, a resume request comprising a resume identity of the UE, where the resume request initiates a resume procedure. The RAN node is further adapted to receive, from the UE, AS release assistance information together with either the resume request or uplink data transmitted by the UE in association with the resume request and determine, based on the AS release assistance information, to perform early RRC release of the UE.

[0046] In one embodiment, a RAN node for early RRC release comprises processing circuitry configured to cause the RAN node to receive, from a UE, a resume request comprising a resume identity of the UE, where the resume request initiates a resume procedure. The processing circuitry is further configured to cause the RAN node to receive, from the UE, AS release assistance information together with either the resume request or uplink data transmitted by the UE in association with the resume request and determine, based on the AS release assistance information, to perform early RRC release of the UE.

[0047] Embodiments of a method performed by an AMF are also disclosed. In one embodiment, a method performed by an AMF for RAN-initiated suspension of a connection of a UE comprises receiving, from a RAN node, a suspend request associated with a UE. The method further comprises determining whether there is pending MT data or MT signaling associated with the UE and forwarding the suspend request to a Session Management Function (SMF) or rejecting the suspend request in accordance with a result of the determining whether there is pending MT data or MT signaling associated with the UE.

[0048] In one embodiment, forwarding the suspend request to the SMF or rejecting the suspend request comprises forwarding the suspend request to the SMF if there is no pending MT data or MT signaling associated with the UE and rejecting the suspend request if there is pending MT data or MT signaling associated with the UE.

[0049] In one embodiment, determining whether there is pending MT data or MT signaling associated with the UE comprises determining that there is pending MT data or MT signaling associated with the UE, and forwarding the suspend request to the SMF or rejecting the suspend request comprises rejecting the suspend request responsive to determining that there is pending MT data or MT signaling associated with the UE. In one embodiment, rejecting the suspend request comprises rejecting the suspend request with a cause indicating pending MT data and/or pending MT signaling.

[0050] Corresponding embodiments of an AMF are also disclosed. In one

embodiment, an AMF for RAN-initiated suspension of a connection of a UE is adapted to receive, from a RAN node, a suspend request associated with a UE and determine whether there is pending MT data or MT signaling associated with the UE. The AMF is further adapted to forward the suspend request to a SMF or reject the suspend request in accordance with a result of the determining whether there is pending MT data or MT signaling associated with the UE.

[0051] In one embodiment, an AMF for RAN-initiated suspension of a connection of a UE comprises processing circuitry configured to cause the network node to receive, from a RAN node, a suspend request associated with a UE and determine whether there is pending MT data or MT signaling associated with the UE. The processing circuitry is further configured to cause the AMF to forward the suspend request to a SMF or reject the suspend request in accordance with a result of the determining whether there is pending MT data or MT signaling associated with the UE.

[0052] Embodiments of a method performed by a UE are also disclosed. In one embodiment, a method performed by a UE for early RRC release after transmission of uplink data during an RRC resume procedure comprises sending a resume request to a RAN node. The method further comprises sending, to the RAN node, AS release assistance information together with either the resume request or uplink data transmitted by the UE in association with the resume request and receiving a response to the resume request from the RAN node.

[0053] In one embodiment, the AS release assistance information comprises information about a traffic pattern of the UE.

[0054] In one embodiment, the UE is a Cellular Internet of Things (CIoT) device.

[0055] In one embodiment, the AS release assistance information is sent in relation to user plane CIoT Fifth Generation System (5GS) optimization.

[0056] Corresponding embodiments of a UE are also disclosed. In one embodiment, a UE for early RRC release after transmission of uplink data during an RRC resume procedure is adapted to send a resume request to a RAN node, send, to the RAN node, AS release assistance information together with either the resume request or uplink data transmitted by the UE in association with the resume request, and receive a response to the resume request from the RAN node.

[0057] In one embodiment, the AS release assistance information comprises information about a traffic pattern of the UE.

[0058] In one embodiment, the UE is a CIoT device.

[0059] In one embodiment, a UE for early RRC release after transmission of uplink data during an RRC resume procedure comprises one or more transmitters, one or more receivers, and processing circuitry associated with the one or more transmitters and the one or more receivers. The processing circuitry is configured to cause the UE to send a resume request to a RAN node, send, to the RAN node, AS release assistance information together with either the resume request or uplink data transmitted by the UE in association with the resume request, and receive a response to the resume request from the RAN node.

Brief Description of the Drawings

[0060] The accompanying drawing figures incorporated in and forming a part of this specification illustrate several aspects of the disclosure, and together with the description serve to explain the principles of the disclosure.

[0061] Figure 1 illustrates a conventional Next-Generation Radio Access Network (NG-RAN) initiated Connection Suspend procedure; [0062] Figure 2 illustrates a conventional Connection Resume in CM-IDLE with Suspend procedure;

[0063] Figure 3 illustrates one example of a cellular communications system in which embodiments of the present disclosure may be implemented;

[0064] Figures 4 and 5 are architectures for the cellular communications system for embodiments in which the cellular communications system is a Fifth Generation System (5GS);

[0065] Figure 6 is a flow chart illustrating an exemplary process, performed by a Radio Access Network (RAN) node, for early Radio Resource Control (RRC) release according to some embodiments of the present disclosure;

[0066] Figure 7 is a flow chart illustrating an exemplary process, performed by a RAN node, for early RRC release according to some other embodiments of the present disclosure;

[0067] Figure 8 is a flow chart illustrating an exemplary process, performed by an Access and Mobility Management Function (AMF) for early RRC release according to some embodiments of the present disclosure;

[0068] Figure 9 is a flow chart illustrating an exemplary process performed by an User Equipment (UE) for early RRC release according to some embodiments of the present disclosure;

[0069] Figure 10 is a reproduction of Figure 4.8.2.3-1 of Third Generation

Partnership Project (3GPP) Technical Specification (TS) 23.502;

[0070] Figure 11 is a reproduction of Figure 4.8.1.2-1 of 3GPP TS 23.502;

[0071] Figures 12 through 14 are schematic block diagrams of a network node in accordance with embodiments of the present disclosure; and

[0072] Figures 15 and 16 are schematic block diagrams of a UE in accordance with embodiments of the present disclosure.

Detailed Description

[0073] The embodiments set forth below represent information to enable those skilled in the art to practice the embodiments and illustrate the best mode of practicing the embodiments. Upon reading the following description in light of the accompanying drawing figures, those skilled in the art will understand the concepts of the disclosure and will recognize applications of these concepts not particularly addressed herein. It should be understood that these concepts and applications fall within the scope of the disclosure.

[0074] Radio Node: As used herein, a "radio node" is either a radio access node or a wireless device.

[0075] Radio Access Node: As used herein, a "radio access node" or "radio network node" or "RAN node" is any node in a radio access network of a cellular communications network 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., a New Radio (NR) base station (gNB) in a Third Generation Partnership Project (3GPP) Fifth Generation (5G) NR network (i.e., a Next Generation Radio Access Network (NG-RAN)) or an enhanced or evolved Node B (eNB) in a 3GPP Long Term Evolution (LTE) network), a high-power or macro base station, a low-power base station (e.g., a micro base station, a pico base station, a home eNB, or the like), and a relay node.

[0076] Core Network Node: As used herein, a "core network node" is any type of node in a core network or any node that implements a core network function. Some examples of a core network node include, e.g., a Mobility Management Entity (MME), a Packet Data Network Gateway (P-GW), a Service Capability Exposure Function (SCEF), a Home Subscriber Server (HSS), or the like. Some other examples of a core network node include a node implementing a Access and Mobility Function (AMF), a UPF, a Session Management Function (SMF), an Authentication Server Function (AUSF), a Network Slice Selection Function (NSSF), a Network Exposure Function (NEF), a

Network Function (NF) Repository Function (NRF), a Policy Control Function (PCF), a Unified Data Management (UDM), or the like.

[0077] Wireless Device: As used herein, a "wireless device" is any type of device that has access to (i.e., is served by) a cellular communications network by wirelessly transmitting and/or receiving signals to a radio access node(s). Some examples of a wireless device include, but are not limited to, a User Equipment device (UE) in a 3GPP network and a Machine Type Communication (MTC) device.

[0078] Network Node: As used herein, a "network node" is any node that is either part of the radio access network or the core network of a cellular communications network/system.

[0079] 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.

[0080] Note that, in the description herein, reference may be made to the term "cell"; however, particularly with respect to 5G NR concepts, beams may be used instead of cells and, as such, it is important to note that the concepts described herein are equally applicable to both cells and beams.

[0081] There currently exist certain challenge(s). The current specified procedures in 3GPP Technical Specification (TS) 23.502, Version 16.1.1, clauses 4.8.1.2 and 4.8.2.3 lack the possibility to do an "Early RRC Release" based on release assistance

information provided by the UE and/or by the AMF/UDM. The NG-RAN in existing solutions needs to depend on an Inactivity timer to decide when the RRC connection can be released. This means the UE will have to stay in active transmitting state for several seconds longer than otherwise would have been necessary if release assistance information had been considered. Minimizing the UE power consumption is an important goal in 3GPP standardization since many Cellular Internet of Things (CIoT) devices are battery operated.

[0082] Certain aspects of the present disclosure and their embodiments may provide solutions to the aforementioned or other challenges.

1. The procedure in TS 23.502 clause 4.8.2.3 "Connection Resume in CM-IDLE with Suspend" has been updated with instructions about how to release assistance information shall be considered for allowing Early RRC Release.

2. The procedure in TS 23.502 clause 4.8.1.2 "Connection Suspend" has been

updated with instructions how to avoid suspending the RRC Connection when there are subsequent data that need to be transmitted, i.e., when Early RRC Release cannot be done.

3. TS 23.502 clause 4.15.6.3 "Expected UE Behavior parameters" has been updated to ensure release assistance information (i.e., Traffic Pattern) is downloaded to the NG-RAN not only for Narrowband Internet of Things (NB-IoT) but also for LTE for MTC (LTE-M) categories of CIoT devices.

[0083] A possibility to reduce the time IoT devices using the 3GPP User Plane CioT 5GS Optimization need to have their radio transmitter switched on when the traffic pattern for the transmission is known. For battery operated IoT devices, this means the UE power consumptions will be reduced. Especially for IoT devices doing frequent data transmissions, this may become a significant reduction in UE power consumption.

Currently, the known traffic pattern where this can be done is single uplink packet transmission (i.e., unacknowledged/unconfirmed transmission) and dual packet transmission (acknowledged/confirmed transmission) uplink or downlink. It may also be possible to optimize for other traffic patterns.

[0084] Certain embodiments may provide one or more of the following technical advantage(s). This solution provides a way for the NG-RAN to make an Early RRC Release to optimize radio resource usage and minimize UE power consumption when the User Plane CIoT 5G System (5GS) Optimization is used.

[0085] Figure 3 illustrates one example of a cellular communications system 300 in which embodiments of the present disclosure may be implemented. In the

embodiments described herein, the cellular communications system 300 is a 5GS including a NR RAN. In this example, the RAN includes base stations 302-1 and 302-2, which in 5G NR are referred to as gNBs, controlling corresponding (macro) cells 304-1 and 304-2. The base stations 302-1 and 302-2 are generally referred to herein collectively as base stations 302 and individually as base station 302. The base stations 302 are also referred to herein as RAN nodes. Likewise, the (macro) cells 304-1 and 304-2 are generally referred to herein collectively as (macro) cells 304 and individually as (macro) cell 304. The RAN may also include a number of low power nodes 306-1 through 306-4 controlling corresponding small cells 308-1 through 308-4. The low power nodes 306-1 through 306-4 can be small base stations (such as pico or femto base stations) or Remote Radio Heads (RRHs), or the like. Notably, while not illustrated, one or more of the small cells 308-1 through 308-4 may alternatively be provided by the base stations 302. The low power nodes 306-1 through 306-4 are generally referred to herein collectively as low power nodes 306 and individually as low power node 306. Likewise, the small cells 308-1 through 308-4 are generally referred to herein collectively as small cells 308 and individually as small cell 308. The cellular communications system 300 also includes a core network 310, which in the 5GS is referred to as the 5G core (5GC). The base stations 302 (and optionally the low power nodes 306) are connected to the core network 310.

[0086] The base stations 302 and the low power nodes 306 provide service to wireless devices 312-1 through 312-5 in the corresponding cells 304 and 308. The wireless devices 312-1 through 312-5 are generally referred to herein collectively as wireless devices 312 and individually as wireless device 312. The wireless devices 312 are also sometimes referred to herein as UEs.

[0087] Figure 4 illustrates a wireless communication system represented as a 5G network architecture composed of core Network Functions (NFs), where interaction between any two NFs is represented by a point-to-point reference point/interface.

Figure 4 can be viewed as one particular implementation of the system 300 of Figure 3.

[0088] Seen from the access side the 5G network architecture shown in Figure 4 comprises a plurality of UEs 312 connected to either a RAN 302 or an Access Network (AN) as well as an AMF 400. Typically, the R(AN) 302 comprises base stations, e.g. such as eNBs or gNBs or similar. Seen from the core network side, the 5GC NFs shown in Figure 4 include a NSSF 402, an AUSF 404, a UDM 406, the AMF 400, a SMF 408, a PCF 410, and an Application Function (AF) 412.

[0089] Reference point representations of the 5G network architecture are used to develop detailed call flows in the normative standardization. The N1 reference point is defined to carry signaling between the UE 312 and AMF 400. The reference points for connecting between the AN 302 and AMF 400 and between the AN 302 and UPF 414 are defined as N2 and N3, respectively. There is a reference point, Nil, between the AMF 400 and SMF 408, which implies that the SMF 408 is at least partly controlled by the AMF 400. N4 is used by the SMF 408 and UPF 414 so that the UPF 414 can be set using the control signal generated by the SMF 408, and the UPF 414 can report its state to the SMF 408. N9 is the reference point for the connection between different UPFs 414, and N14 is the reference point connecting between different AMFs 400,

respectively. N15 and N7 are defined since the PCF 410 applies policy to the AMF 400 and SMF 408, respectively. N12 is required for the AMF 400 to perform authentication of the UE 312. N8 and N10 are defined because the subscription data of the UE 312 is required for the AMF 400 and SMF 408.

[0090] The 5GC network aims at separating UP and CP. The UP carries user traffic while the CP carries signaling in the network. In Figure 4, the UPF 414 is in the UP and all other NFs, i.e., the AMF 400, SMF 408, PCF 410, AF 412, NSSF 402, AUSF 404, and UDM 406, are in the CP. Separating the UP and CP guarantees each plane resource to be scaled independently. It also allows UPFs to be deployed separately from CP functions in a distributed fashion. In this architecture, UPFs may be deployed very close to UEs to shorten the Round Trip Time (RTT) between UEs and data network for some applications requiring low latency.

[0091] The core 5G network architecture is composed of modularized functions. For example, the AMF 400 and SMF 408 are independent functions in the CP. Separated AMF 400 and SMF 408 allow independent evolution and scaling. Other CP functions like the PCF 410 and AUSF 404 can be separated as shown in Figure 4. Modularized function design enables the 5GC network to support various services flexibly.

[0092] Each NF interacts with another NF directly. It is possible to use intermediate functions to route messages from one NF to another NF. In the CP, a set of interactions between two NFs is defined as service so that its reuse is possible. This service enables support for modularity. The UP supports interactions such as forwarding operations between different UPFs.

[0093] Figure 5 illustrates a 5G network architecture using service-based interfaces between the NFs in the CP, instead of the point-to-point reference points/interfaces used in the 5G network architecture of Figure 4. Flowever, the NFs described above with reference to Figure 4 correspond to the NFs shown in Figure 5. The service(s) etc. that a NF provides to other authorized NFs can be exposed to the authorized NFs through the service-based interface. In Figure 5 the service based interfaces are indicated by the letter "N" followed by the name of the NF, e.g. Namf for the service based interface of the AMF 400 and Nsmf for the service based interface of the SMF 408, etc. The NEF 500 and the NRF 502 in Figure 5 are not shown in Figure 4 discussed above. Flowever, it should be clarified that all NFs depicted in Figure 4 can interact with the NEF 500 and the NRF 502 of Figure 5 as necessary, though not explicitly indicated in Figure 4.

[0094] Some properties of the NFs shown in Figures 4 and 5 may be described in the following manner. The AMF 400 provides UE-based authentication, authorization, mobility management, etc. A UE 312 even using multiple access technologies is basically connected to a single AMF 400 because the AMF 400 is independent of the access technologies. The SMF 408 is responsible for session management and allocates Internet Protocol (IP) addresses to UEs. It also selects and controls the UPF 414 for data transfer. If a UE 312 has multiple sessions, different SMFs 408 may be allocated to each session to manage them individually and possibly provide different functionalities per session. The AF 412 provides information on the packet flow to the PCF 410 responsible for policy control in order to support QoS. Based on the information, the PCF 410 determines policies about mobility and session management to make the AMF 400 and SMF 408 operate properly. The AUSF 404 supports authentication function for UEs or similar and thus stores data for authentication of UEs or similar while the UDM 406 stores subscription data of the UE 312. The Data Network (DN), not part of the 5GC network, provides Internet access or operator services and similar.

[0095] An NF may be implemented either as a network element on a dedicated hardware, as a software instance running on a dedicated hardware, or as a virtualized function instantiated on an appropriate platform, e.g., a cloud infrastructure.

Improved UE Behavior Parameter Handling

[0096] According to some embodiments of the present disclosure, the Expected UE Behavior parameters may be downloaded to the NG-RAN not only for NB-IoT devices but also for LTE-M categories of CIoT devices. This ensures that release assistance information (i.e., traffic pattern) is available for use by the NG-RAN during the improved procedures described below.

Improved Connection Suspend

[0097] During a NG-RAN initiated Connection Suspend procedure according to some embodiments of the present disclosure, before the NG-RAN sends the N2 Suspend Request message to the AMF, the NG-RAN checks to see whether the UE context in the NG-RAN contains an indicator that indicates pending mobile terminating (MT) data or MT signaling, and sends the N2 Suspend Request message to the AMF only if the NG- RAN has nothing to indicate pending MT data and MT signaling. Likewise, if the AMF is aware of pending MT data or MT signaling, the AMF will reject the N2 Suspend Request with a cause indicating pending MT data and/or signaling. In contrast, conventional methods do not defer or deny an N2 Suspend Request based on an indicator of pending MT data or MT signaling.

Improved Connection Resume

[0098] During a Connection Resume procedure used by a UE to perform RRC_IDLE with Suspend to RRC_CONNECTED state transition, the UE provides its Resume ID needed by the NG-RAN to access the UE's stored context. During a Connection Resume procedure according to some embodiments of the present disclosure, if the UE initiated the transition to CM-CONNECTED and RRC Connected state in order to transmit uplink data and the application in the UE has provided release assistance information, the UE may provide Access Stratum (AS) Release Assistance Information together with the RRC message or together with the uplink data. The NG-RAN may use the AS Release Assistance Information and/or Traffic Profile parameters in the Expected UE Behavior, which may be stored in the UE Context in the NG-RAN if earlier provided by AMF at NGAP UE association establishment, to decide to do an early RRC release directly after the expected data transmission(s) have been done. The AS Release Assistance

Information takes precedence if both that and the Traffic Profile are available in the NG- RAN.

Example Embodiments

[0099] Figure 6 is a flow chart illustrating an exemplary process, performed by a RAN node 302, for early RRC release according to some embodiments of the present disclosure. This process may be performed in relation to the improved Connection Suspend procedure described above. In the embodiment illustrated in Figure 6, the process includes the following steps:

[0100] Step 602: During a RAN initiated Connection Suspend procedure in relation to a UE 312, before sending a suspend request message to the AMF 400, the RAN node 302 determines whether there is pending MT data or signaling associated with the UE 312.

[0101] Step 604: Upon determining that there is no pending MT data or signaling associated with the UE, the RAN node 302 sends the suspend request to the AMF 400 associated with the UE 312.

[0102] Step 606: Upon determining that there is pending MT data or signaling associated with the UE, the RAN node 302 refrains from sending a suspend request to the AMF 400 associated with the UE 312.

[0103] Figure 7 is a flow chart illustrating an exemplary process, performed by a RAN node 302, for early RRC release according to some embodiments of the present disclosure. This process may be performed for the improved connection resume procedure described above. In the embodiment illustrated in Figure 7, the process includes the following steps: [0104] Step 700: The RAN node 302 receives, from a UE 312, a resume request, the resume request comprising Access Stratum release assistance information. In addition, as described above, the resume request also includes a Resume ID of the UE 312. As also described above, the AS release assistance information is provided when the UE 312 initiated the resume in order to transmit uplink data and the application in the UE 312 has provided release information. As also described above, as an alternative to including the AS release assistance information in the resume request, the AS release assistance information may be provided together with uplink data being transmitted by the UE 312 during the resume procedure.

[0105] Step 702: The RAN node 302 determines, based on the AS release assistance information, to perform early RRC release. As described above, the RAN node 302 may determine whether to perform an early release directly after the expected data transmission(s) have been done based on the AS release assistance information and/or a traffic profile parameter(s) in an Expected UE Behavior of the UE 312 (e.g., stored in the UE context of the UE 312). As also described above, the AS release assistance information takes precedence if both the AS release assistance information and the traffic profile of the UE 312 are available in the RAN node 302.

[0106] Figure 8 is a flow chart illustrating an exemplary process, performed by an AMF 400, for early RRC release according to some embodiments of the present disclosure. This process may be performed in the improved Connection Suspend procedure described above. In the embodiment illustrated in Figure 8, the process includes the following steps:

[0107] Step 800: The AMF 400 receives, from a RAN node 302, a suspend request associated with a UE 312.

[0108] Step 802: The AMF 400 determines whether there is pending MT data or signaling associated with the UE 312.

[0109] Step 804: Upon determining that there is no pending MT data or signaling associated with the UE 312, the AMF 400 forwards the suspend request to a SMF 408.

[0110] Step 806: Upon determining that there is pending MT data or signaling associated with the UE 312, the AMF 400 rejects the suspend request.

[0111] Figure 9 is a flow chart illustrating an exemplary process, performed by an UE 312, for early RRC release according to some embodiments of the present disclosure.

In the embodiment illustrated in Figure 9, the process includes the following steps: [0112] Step 900: The UE 312 sends, to a RAN node 302, a resume request, the resume request comprising Access Stratum release assistance information. As discussed above, the resume request also includes a Resume ID of the UE 312. As also described above, the AS release assistance information is provided when the UE 312 initiated the resume in order to transmit uplink data and the application in the UE 312 has provided release information. As also described above, as an alternative to including the AS release assistance information in the resume request, the AS release assistance information may be provided together with uplink data being transmitted by the UE 312 during the resume procedure.

[0113] Step 902: The UE 312 receives, from the RAN node 302, a response to the resume request.

Example Implementation

[0114] One example implementation of at least some aspects of the embodiments described above is shown below in the form of changes to 3GPP TS 23.501 V16.1.0. Additions are shown with underlining. Deletions are shown with strikethroughs.

****************g^py Qp CHANGES TO 3GPP TS 23 501 V16 1 0***************

5.31 .18 User Plane CloT 5GS Optimisation

User Plane CloT 5GS Optimisation enables transfer of user plane data from CM-IDLE without the need for using the Service Request procedure to establish Access Stratum (AS) context in NG-RAN and UE.

If the following preconditions are met:

UE and AMF negotiated support User Plane CloT 5GS Optimisation (see clause 5.31.2) over NAS, the UE has indicated support of User Plane CloT 5GS Optimisation in the UE radio capabilities as defined in TS 36.331 [51],

- AMF has indicated User Plane CloT 5GS Optimisation support to NG-RAN,

the UE has established at least one PDU session with active UP connection, i.e. AS context is established in NG-RAN and the UE,

then the RRC connection can be suspended by means of the Connection Suspend Procedure (see clause 4.8.1.2 of TS 23.502 [3]).

Based on a trigger from the NAS layer when a UE is in CM-IDLE with Suspend, the UE should attempt the Connection Resume in CM-IDLE with Suspend procedure (clause 4.8.2.3 of TS 23.502 [3]). If the Connection Resume in CM-IDLE with Suspend procedure fails, the UE initiates the pending NAS procedure. To maintain support for User Plane CloT 5GS Optimisation for UE mobility across different NG-RAN nodes, the AS Context should be transferred between the NG-RAN nodes, see TS 38.300 [27] and TS 38.423 [99].

By using the Connection Suspend Procedure:

the UE at transition into CM-IDLE stores the AS information; NG-RAN stores the AS information, the NGAP UE association and the PDU session context for that UE;

AMF stores the NGAP UE association and other information necessary to later resume the UE, interacts with the SMF(s) to deactivate the user plane resources for the UE's PDU Sessions and enters CM-IDLE.

NG-RAN may decide based on implementation to delete the stored UE context and NGAP association. In that case, the RAN shall initiate the AN Release procedure as described in clause 4.2.6 of TS 23.502 [3]. NG-RAN does not initiate any RRC procedure to notify the UE of the UE context release.

By using the Connection Resume in CM-IDLE with Suspend procedure:

the UE resumes the connection from CM-IDLE with the network using the AS information stored during the Connection Suspend procedure;

the NG-RAN node notifies the AMF that the connection with the UE has been resumed and the AMF enters CM-CONNECTED and interacts with the SMF to activate the user plane resources for the UE's PDU Sessions.

The UE may include early uplink data in the Connection Resume and/or early downlink data in the Connection Suspend.

If provided by the application in the UE, the UE may provide AS Release Assistance Information together with uplink data. When the AMF establishes an NGAP UE association with a NG-RAN node, it should for LTE-M UEs and NB-IoT UEs provide the Expected UE Behaviour parameters to the RAN to allow optimisation of Uu resource allocation. The Traffic Profile in the Expected UE Behaviour and the AS Release Assistance Information may for example be used by the NG-RAN to decide to do an Early RRC release after data transmission^ have been done.

If the AMF establishes an NGAP UE association with a new NG-RAN node different from the stored NGAP UE association, e.g. the UE initiates service request or registration procedure from a different NG-RAN node, the AMF initiates UE N2 release command towards the old NG-RAN node.

NG-RAN maintains the N3 tunnel endpoint information while a UE is in CM-IDLE with Suspend. UPF is instructed to remove DL N3 Tunnel Info of AN during Connection Suspend procedure, while UPF keeps UL N3 Tunnel Info (i.e. UPF accepts and forwards UL data).

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[0115] One example implementation of at least some aspects of the embodiments described above is shown below in the form of changes to 3GPP TS 23.502 V16.1.0. Additions are shown with underlining. Deletions are shown with strikethroughs.

************** * *START OF CHANGES TO 3GPP TS 23 502 V16 1 0***************

4.8.2.3 Connection Resume in CM-IDLE with Suspend procedure

For the UE supporting User Plane CIoT 5GS Optimisation, the Connection Resume procedure is used by the UE to perform RRC_IDLE with Suspend to RRC_CONNECTED state transition. Triggers for the UE to initiate this procedure are defined in TS 23.501 [2], clause 5.31.18.

[see FIGURE 10]

Figure 4.8.2.3-1 : Connection Resume in CM-IDLE with Suspend 1. UE to NG-RAN: RRC message (Resume ID). The UE initiates the transition from CM-IDLE and RRC IDLE state with Suspend to CM- CONNECTED and RRC Connected state, see TS 36.300 [46]. The UE provides its Resume ID needed by the NG-RAN to access the UE's stored Context.

If the UE initiated the transition to CM-CQNNECTED and RRC Connected state in order to transmit uplink data and the application in the UE has provided release assistance information, the UE may provide AS Release Assistance Information together with the RRC message or together with the uplink data. The NG-RAN may use the AS Release Assistance Information and/or Traffic Profile parameters in the Expected UE Behaviour, which may be stored in the UE Context in NG-RAN if earlier provided by AMF at NGAP UE association establishment, to decide to do an early RRC release directly after the expected data transmission(s) have been done. The AS Release Assistance Information takes precedence if both that and the Traffic Profile are available in the NG-RAN.

2. [Conditional] NG-RAN performs UE Context Retrieval.

UE Context Retrieval may be performed when the UE Context associated with the UE attempting to resume its connection is not locally available at the accessed NG-RAN. The UE Context Retrieval procedure via radio access network is specified in TS 38.300 [9].

3. NG-RAN and UE continues the resume procedure and access stratum configuration

synchronization is performed between the UE and the network. UE enters CM- CONNECTED and RRC_CONNECTED.

4. NG-RAN to AMF:

a) If the NG-RAN is the same as the NG-RAN when UE is suspended, the NG-RAN sends N2 Resume Request to AMF including Resume cause, and N2 SM information which indicates the PDU sessions successfully resumed, and PDU sessions failed or partially failed to resume the user plane resource.

b) If the NG-RAN is different from the NG-RAN when UE is suspended, and the new NG- RAN is able to retrieve the UE Context from the old NG-RAN, the new NG-RAN node initiates N2 Path Switch Request towards AMF, i.e. Steps lb of clause 4.9.1.2.2.

5. AMF to SMF: For each of the PDU Sessions indicated in step 4, the AMF invokes

Nsmf_PDUSession_UpdateSMContext Request (PDU Session ID, Cause, Operation type, User Location Information, Age of Location Information, N2 SM Information). The Operation Type is set to "UP Resume" to indicate resume of user plane resources for the PDU Session.

For PDU Session(s) to be switched to the new NG-RAN, upon receipt of the

Nsmf_PDUSession_UpdateSMContext request, the SMF determines whether the existing UPF can continue to serve the UE. If the existing UPF cannot continue to serve the UE, steps 3 to 7 of clause 4.9.1.2.3 or clause 4.9.1.2.4 are performed depending on whether the existing UPF is a PDU Session Anchor and flow continues in step 7. Otherwise, step 6 is performed if the existing UPF can continue to serve the PDU Session.

6. SMF to UPF: N4 Session Modification Request (AN Tunnel Info to be resumed, Buffering on/off).

The SMF initiates an N4 Session Modification procedure indicating the resume of AN tunnel. Buffering on/off indicates whether the UPF shall buffer incoming DL PDU or not.

The UPF sends N4 Session Modification Response to acknowledge the SMF request. 7. SMF to AMF: The SMF sends Nsmf_PDUSession_UpdateSMContext response to the AMF.

If new CN tunnel information is allocated for the PDU session, the SMF includes the new CN tunnel information as part of the N2 SM information.

If the resume for PDU session is unsuccessful, the SMF shall include the resume failure as part of the N2 SM information.

8. AMF to NG-RAN: After response for each PDU session in step 7, the AMF sends N2 Resume Response to NG-RAN and indicates success, including N2 SM information for PDU session received in step 7, if at least one PDU session is resumed successfully. If none of the PDU sessions is resumed successfully, AMF indicates failure to NG-RAN.

The AMF sends N2 Path Switch Acknowledge with PDU session resume information, if Path Switch Request is received in step 4.

The AMF may provide Extended Connected Time value to the NG-RAN. If the NG-RAN receives the Extended Connected Time value, the NG-RAN may take this information into account when determining user inactivity.

9. [Conditional] NG-RAN to UE: RRC message.

The NG-RAN may reconfigure the RRC connection based on resume result received from AMF.

*******************|^0Q- CHANGE TO 3GPP TS 23 502 V16 1 0***************** 4.8.1.2 Connection Suspend procedure

This procedure may be initiated by the serving NG-RAN node when the UE is in CM- CONNECTED and has at least one PDU session with active user plane connection, and NG-eNB has received indication from the AMF that User Plane CIoT 5GS Optimisation, as defined in TS 23.501 [2] clause 5.31.18, is supported for the UE.

[SEE FIGURE 11]

Figure 4.8.1.2-1 : NG-RAN initiated Connection Suspend procedure

1. NG-RAN to AMF: ALT1: If NG-RAN has no Pending DL data/signalling indicator set in the UE Context in NG-RAN indicating pending MT data and MT signalling the The-NG-

RAN sends the N2 Suspend Request message to the AMF, see TS 38.413 [10]. The AMF enters CM-IDLE with Suspend indicator. Context information related to the NGAP UE association, UE Context and PDU session context, necessary to resume the connection is stored in the UE, NG-RAN node and in the AMF. The NG-RAN may include the Suspend cause, and the N2 SM information.

The NG-RAN may include the Information On Recommended Cells And NG-RAN For Paging in the N2 Suspend Request message. If available, the AMF shall store this information to be used when paging the UE.

The NG-RAN includes Information for Enhanced Coverage, if available, in the N2 Suspend Request message. If Service Gap Control is being applied to the UE (see clause 4.3.17.9) and the Service Gap timer is not already running, the Service Gap timer shall be started in the AMF when entering CM-IDLE, unless the connection was initiated after a paging of an MT event, or after a mobility registration procedure without Follow-on Request indication.

ALT2: If the AMF is aware of pending MT data or MT signalling, the AMF shall reject the N2 Suspend Request with a cause indicating pending MT data/signalling .

2. AMF to SMF: For each of the PDU Sessions in the N2 Suspend Request, the AMF invokes Nsmf_PDUSession_UpdateSMContext Request (PDU Session ID, Cause, Operation type, User Focation Information, Age of Focation Information, N2 SM Information (Secondary RAT usage data)). The Operation Type is set to "UP Suspend" to indicate suspend of user plane resources for the PDU Session.

3. SMF to UPF: N4 Session Modification Request (AN Tunnel Info to be suspended,

Buffering on/off).

The SMF initiates an N4 Session Modification procedure indicating the need to release the tunnel info of AN or UPF terminating N3. Buffering on/off indicates whether the UPF shall buffer incoming DF PDU or not.

The UPF sends N4 Session Modification Response to acknowledge the SMF request.

4. SMF to AMF: The SMF sends Nsmf_PDUSession_UpdateSMContext response to the AMF.

5. AMF to NG-RAN: After response for each PDU session in step 4, the AMF sends N2

Suspend Response to NG-RAN to successfully terminate the Connection Suspend procedure initiated by the NG-RAN, see TS 38.413 [10].

6. The NG-RAN sends RRC message to suspend the RRC Connection towards the UE including UE Resume ID, see TS 36.300 [46]).

If Service Gap Control is applied for the UE (see TS 23.501 [2] clause 5.31.16) and the Service Gap timer is not already running, the Service Gap timer shall be started in the UE when entering CM-IDFE, unless the connection was initiated as a response to paging of an MT event, or after a mobility registration procedure without Follow-on Request Indication set.

*******************|^0Q- CHANGE TO 3GPP TS 23 502 V16 1 0***************** 4.15.6.3 Expected UE Behaviour parameters

These Expected UE Behaviour parameters characterise the foreseen behaviour of a UE or a group of UEs. Sets of these parameters may be provided via the NEF to be stored as part of the subscriber data. Each parameter within the Expected UE Behaviour shall have an associating validity time. The validity time indicates when the Expected UE Behaviour parameter expires and shall be deleted by the related NFs. The validity time may be set to indicate that the particular Expected UE Behaviour parameter has no expiration time. When the validity time expires, the related NFs delete their local copy of the associated Expected UE Behaviour parameter(s). The provision procedure of the Expected UE Behaviour is realized by external parameter provision procedure defined in clause 4.15.6.2. Table 4.15.6.3-1 : Description of Expected UE Behaviour parameters

The Expected UE Moving Trajectory may be used by the AMF. All other parameters may be used by the AMF and by the SMF.

The Scheduled Communication Type and the Traffic Profile should not be used by the AMF to release the UE when NAS Release Assistance Indication from the UE is available. In the case of NB-IoT UEs, the parameters may be forwarded to the RAN to allow optimisation of Uu resource allocation for NB-IoT UE differentiation. In the case of LTE-M UEs. the parameters may be forwarded to the RAN to allow optimisation of Uu resource allocation.

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Additional Aspects

[0116] Figure 12 is a schematic block diagram of a network node 1200 according to some embodiments of the present disclosure. The network node 1200 may be a radio access node, such as, for example, a base station 302 or 306, or a core network node, such as, for example, an AMF, SMF, etc. As illustrated, the network node 1200 includes a control system 1202 that includes one or more processors 1204 (e.g., Central

Processing Units (CPUs), Application Specific Integrated Circuits (ASICs), Field

Programmable Gate Arrays (FPGAs), and/or the like), memory 1206, and a network interface 1208. The one or more processors 1204 are also referred to herein as processing circuitry. In addition, the network node 1200 may include one or more radio units 1210 that each includes one or more transmitters 1212 and one or more receivers 1214 coupled to one or more antennas 1216. The radio units 1210 may be referred to or be part of radio interface circuitry. In some embodiments, the radio unit(s) 1210 is external to the control system 1202 and connected to the control system 1202 via, e.g., a wired connection (e.g., an optical cable). Flowever, in some other embodiments, the radio unit(s) 1210 and potentially the antenna(s) 1216 are integrated together with the control system 1202. The one or more processors 1204 operate to provide one or more functions of a network node 1200 as described herein. In some embodiments, the function(s) are implemented in software that is stored, e.g., in the memory 1206 and executed by the one or more processors 1204.

[0117] Figure 13 is a schematic block diagram that illustrates a virtualized

embodiment of the network node 1200 according to some embodiments of the present disclosure. This discussion is equally applicable to other types of network nodes.

Further, other types of network nodes may have similar virtualized architectures.

[0118] As used herein, a "virtualized" network node is an implementation of the network node 1200 in which at least a portion of the functionality of the network node 1200 is implemented as a virtual component(s) (e.g., via a virtual machine(s) executing on a physical processing node(s) in a network(s)). As illustrated, in this example, the network node 1200 includes the control system 1202 that includes the one or more processors 1204 (e.g., CPUs, ASICs, FPGAs, and/or the like), the memory 1206, and the network interface 1208 and the one or more radio units 1210 that each includes the one or more transmitters 1212 and the one or more receivers 1214 coupled to the one or more antennas 1216, as described above. The control system 1202 is connected to the radio unit(s) 1210 via, for example, an optical cable or the like. The control system 1202 is connected to one or more processing nodes 1300 coupled to or included as part of a network(s) 1302 via the network interface 1208. Each processing node 1300 includes one or more processors 1304 (e.g., CPUs, ASICs, FPGAs, and/or the like), memory 1306, and a network interface 1308.

[0119] In this example, functions 1310 of the network node 1200 described herein are implemented at the one or more processing nodes 1300 or distributed across the control system 1202 and the one or more processing nodes 1300 in any desired manner. In some particular embodiments, some or all of the functions 1310 of the network node 1200 described herein are implemented as virtual components executed by one or more virtual machines implemented in a virtual environment(s) hosted by the processing node(s) 1300. As will be appreciated by one of ordinary skill in the art, additional signaling or communication between the processing node(s) 1300 and the control system 1202 is used in order to carry out at least some of the desired functions 1310. Notably, in some embodiments, the control system 1202 may not be included, in which case the radio unit(s) 1210 communicate directly with the processing node(s) 1300 via an appropriate network interface(s).

[0120] In some embodiments, a computer program including instructions which, when executed by at least one processor, causes the at least one processor to carry out the functionality of network node 1200 or a node (e.g., a processing node 1300) implementing one or more of the functions 1310 of the network node 1200 in a virtual environment according to any of the embodiments described herein is provided. In some embodiments, a carrier comprising the aforementioned computer program product is provided. The carrier is one of an electronic signal, an optical signal, a radio signal, or a computer readable storage medium (e.g., a non-transitory computer readable medium such as memory).

[0121] Figure 14 is a schematic block diagram of the network node 1200 according to some other embodiments of the present disclosure. The network node 1200 includes one or more modules 1400, each of which is implemented in software. The module(s) 1400 provide the functionality of the network node 1200 described herein. This discussion is equally applicable to the processing node 1300 of Figure 13 where the modules 1400 may be implemented at one of the processing nodes 1300 or distributed across multiple processing nodes 1300 and/or distributed across the processing node(s) 1300 and the control system 1202.

[0122] Figure 15 is a schematic block diagram of a UE 1500 according to some embodiments of the present disclosure. As illustrated, the UE 1500 includes one or more processors 1502 (e.g., CPUs, ASICs, FPGAs, and/or the like), memory 1504, and one or more transceivers 1506 each including one or more transmitters 1508 and one or more receivers 1510 coupled to one or more antennas 1512. The transceiver(s) 1506 includes radio-front end circuitry connected to the antenna(s) 1512 that is configured to condition signals communicated between the antenna(s) 1512 and the processor(s) 1502, as will be appreciated by on of ordinary skill in the art. The processors 1502 are also referred to herein as processing circuitry. The transceivers 1506 are also referred to herein as radio circuitry. In some embodiments, the functionality of the UE 1500 described above may be fully or partially implemented in software that is, e.g., stored in the memory 1504 and executed by the processor(s) 1502. Note that the UE 1500 may include additional components not illustrated in Figure 15 such as, e.g., one or more user interface components (e.g., an input/output interface including a display, buttons, a touch screen, a microphone, a speaker(s), and/or the like and/or any other

components for allowing input of information into the UE 1500 and/or allowing output of information from the UE 1500), a power supply (e.g., a battery and associated power circuitry), etc.

[0123] In some embodiments, a computer program including instructions which, when executed by at least one processor, causes the at least one processor to carry out the functionality of the UE 1500 according to any of the embodiments described herein is provided. In some embodiments, a carrier comprising the aforementioned computer program product is provided. The carrier is one of an electronic signal, an optical signal, a radio signal, or a computer readable storage medium (e.g., a non-transitory computer readable medium such as memory).

[0124] Figure 16 is a schematic block diagram of the UE 1500 according to some other embodiments of the present disclosure. The UE 1500 includes one or more modules 1600, each of which is implemented in software. The module(s) 1600 provide the functionality of the UE 1500 described herein.

[0125] 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 one or more embodiments of the present disclosure.

[0126] While processes in the figures may show a particular order of operations performed by certain embodiments of the present disclosure, it should be understood that such order is exemplary (e.g., alternative embodiments may perform the

operations in a different order, combine certain operations, overlap certain operations, etc.).

[0127] Some example embodiments are as follows.

Group A Embodiments - NG-RAN

[0128] Embodiment 1 : A method, performed by a Radio Access Network, RAN, for early Radio Resource Control, RRC, release, the method comprising: determining whether there is pending Mobile Terminated, MT, data or signaling associated with a User Equipment, UE; upon determining that there is no pending MT data or signaling associated with the UE, sending a suspend request to an Access and Mobility

Management Function, AMF, associated with the UE; and upon determining that there is pending MT data or signaling associated with the UE, refraining from sending a suspend request. [0129] Embodiment 2: The method of embodiment 1 wherein determining whether there is pending MT data or signaling associated with the UE comprises determining whether a UE context maintained by the RAN comprises a pending Downlink, DL, data or signaling indicator that indicates that there is pending MT data or signaling

associated with the UE.

[0130] Embodiment 3: A method, performed by a Radio Access Network, RAN, for early Radio Resource Control, RRC, release, the method comprising: receiving, from a User Equipment, UE, a resume request, the resume request comprising Access Stratum, AS, release assistance information; determining, based on the AS release assistance information, to perform early RRC release.

[0131] Embodiment 4: The method of embodiment 3 wherein determining to perform early RRC release comprises determining to perform RRC release directly after one or more uplink data transmissions from the UE are completed.

[0132] Embodiment 5: The method of any of embodiments 3-4 wherein determining to perform early RRC release comprises determining to perform early RRC release based on the AS release assistance information and on an expected UE behavior parameter stored in a UE context maintained by the RAN.

[0133] Embodiment 6: The method of embodiment 5 wherein the expected behavior parameter comprises a traffic pattern parameter.

Group B Embodiments - AMF

[0134] Embodiment 7: A method, performed by an Access and Mobility

Management Function, AMF, for early Radio Resource Control, RRC, release, the method comprising: receiving, from a Radio Access Network, RAN, a suspend request associated with a User Equipment, UE; determining whether there is pending Mobile Terminated, MT, data or signaling associated with the UE; upon determining that there is no pending MT data or signaling associated with the UE, forwarding the suspend request to a Session Management Function, SMF; and upon determining that there is pending MT data or signaling associated with the UE, rejecting the suspend request.

[0135] Embodiment 8: The method of embodiment 7, wherein rejecting the suspend request comprises rejecting the suspend request with a cause indicating pending MT data and/or signaling. Group C Embodiments - UE

[0136] Embodiment 9: A method, performed at a User Equipment, UE, for early Radio Resource Control, RRC, release, the method comprising: sending, to a Radio Access Network, RAN, a resume request, the resume request comprising Access

Stratum, AS, release assistance information; and receiving, from the RAN, a response to the resume request.

[0137] Embodiment 10: A Radio Access Network, RAN, the RAN comprising: one or more processors; and memory storing instructions executable by the one or more processors, whereby the RAN is operable to perform any of the steps of any of the Group A embodiments.

[0138] Embodiment 11: The RAN of embodiment 10, wherein the RAN comprises a Next Generation, NG, RAN.

[0139] Embodiment 12: An Access and Mobility Management Function, AMF, the AMF comprising: one or more processors; and memory storing instructions executable by the one or more processors, whereby the RAN is operable to perform any of the steps of any of the Group B embodiments.

[0140] Embodiment 13: A User Equipment, UE, the UE comprising: one or more processors; and memory storing instructions executable by the one or more processors, whereby the RAN is operable to perform any of the steps of any of the Group C embodiments.

[0141] Embodiment 14: The UE of embodiment 13, wherein the UE comprises a Cellular Internet of Things, CIoT, device.

[0142] At least some of the following abbreviations may be used in this disclosure. If there is an inconsistency between abbreviations, preference should be given to how it is used above. If listed multiple times below, the first listing should be preferred over any subsequent listing(s).

3GPP Third Generation Partnership Project

5G Fifth Generation

5GC Fifth Generation Core

5GS Fifth Generation System

AF Application Function

AMF Access and Mobility Management Function • AN Access Network

• AP Access Point

• ASIC Application Specific Integrated Circuit

• AUSF Authentication Server Function

• CioT Cellular Internet of Things

• CM Connection Management

• CN Core Network

• CPU Central Processing Unit

• DL Downlink

• DN Data Network

• DSP Digital Signal Processor

• eNB Enhanced or Evolved Node B

• E-UTRA Evolved Universal Terrestrial Radio Access

• FPGA Field Programmable Gate Array

• gNB New Radio Base Station

• HSS Flome Subscriber Server

• ID Identifier / Identity

• IoT Internet of Things

• IP Internet Protocol

• LTE Long Term Evolution

• LTE-M Long Term Evolution for Machines

• MME Mobility Management Entity

• MT Mobile Terminated

• MTC Machine Type Communication

• NAS Non-Access Stratum

• NB Narrowband

• NB-IoT Narrowband Internet of Things

• NEF Network Exposure Function

• NF Network Function

• NG Next Generation

• NGAP Next Generation Application Protocol

• NG-RAN Next Generation Radio Access Node

• NR New Radio • NRF Network Function Repository Function

• NSSF Network Slice Selection Function

• OTT Over-the-Top

• PCF Policy Control Function

• PDU Protocol Data Unit

• P-GW Packet Gateway

• QoS Quality of Service

• RAM Random Access Memory

• RAN Radio Access Network

• RAT Radio Access Technology

• ROM Read Only Memory

• RRC Radio Resource Control

• RRH Remote Radio Flead

• RTT Round Trip Time

• SCEF Service Capability Exposure Function

• SMF Session Management Function

• TS Technical Specification

• UDM Unified Data Management

• UE User Equipment

• UL Uplink

• UP User Plane

• UPF User Plane Function

• UTRA Universal Terrestrial Radio Access

[0143] Those skilled in the art will recognize improvements and modifications to the embodiments of the present disclosure. All such improvements and modifications are considered within the scope of the concepts disclosed herein.