CROSS-REFERENCE TO RELATED APPLICATIONS

[001] This application claims the benefit of U.S. Provisional Application No. 63/359,481 filed on July 8, 2022, the entire contents of which are hereby incorporated by reference.

TECHNICAL FIELD

[002] Disclosed are embodiments related to energy efficiency, paging, and RRC inactive in 5G NR and radio access networks.

INTRODUCTION

[003] FIG. 1 illustrates the higher layer split NG-RAN node architecture. A NG-RAN node 100 consists of gNB-CU and gNB-DU logical entities. Core Network 102 connects to the NG-RAN node 100 over N2 interface at the control plane, and N3 interface over the user plane depicted as NG in FIG. 1. The gNBs are connected through the Xn interface between the gNB-CUs. In the split architecture, gNB-CU and a gNB-DU are connected via Fl interface. SDAP/PDCP and RRC protocol resides in gNB-CU. RLC/MAC/PHY protocols reside in gNB-DU.

[004] In 5G, a new RRC Stats called "RRC Inactive" is introduced to reduce the setup procedure latency and the signaling load as compared to the corresponding setup procedure from “RRC Idle.” During RRC Inactive, the radio resources are released, but the UE Context is stored at the gNB and UE and the CN connection is kept. As result of storing the UE Context, transitions from RRC Inactive to RRC Connected is quicker compared to corresponding transition from Idle since fewer information element exchanges are needed for subsequent connections. The CN may be notified by the NG-RAN node 100 that the UE goes in/out the RRC Inactive state.

[005] There are two Paging methods defined in 3GPP NR specification: core network paging and RAN paging.

[006] Core Network Paging

[007] FIG. 2 illustrates a core network paging procedure. Core network paging enables the Access and Mobility Management Function (AMF) 204 of the CN to page an Idle mode UE in the specific NG-RAN node 200. A UE paging identity is used to represent the Identity of the UE being paged. At the reception of the PAGING message 201, the NG-RAN node 200 shall perform paging of the UE in cells that belong to tracking areas as indicated in the TAI List for Paging IE.

[008] RAN Paging

[009] FIG. 3 illustrates a RAN paging procedure. For the UE in RRC IN ACTIVE, if there is downlink data or signaling from CN, the last serving gNB 300 pages the UE in the cells corresponding to the RNA (RAN Based Notification Area). This can include sending Paging 301 to neighbor gNB(s) 306, which belong to the RNA over Xn Interface. The UE RAN Paging Identity defines the UE Identity for RAN paging a UE in RRC INACTIVE.

SUMMARY

[0010] Stationary UEs often stay at the one or few of the up to 64 Synchronization Signal Blocks (SSBs) in the Cell. The typical/standard behavior for a gNB is to repeat (aka sweep) the very same paging message in same number of beams as the SSBs, where said beams have QCL relationship. The problem with such scheme is twofold. First, at high paging loads, the network (NW) paging resources become limited as each beam instance is unnecessarily filled with identities of the UEs, which are decoding one or a few instances of the beams. Second, at low paging loads, the unnecessary transmission/repetitions waste NW energy.

[0011] Aspects of the present disclosure provide a solution for the network to select a subset of SSBs where the UE is likely to be instead of paging all beams corresponding to SSBs in the cell. Network energy efficiency is enhanced by using less radio resources.

[0012] Aspects of the present disclosure include that the gNB-DU provides the serving/most probable SSB information to gNB-CU for the given UE. The given SSB information should be able to identity the SSB in the gNB-DU, for example, including the Cell ID and one or more SSB Indices.

[0013] If the UE context is kept in a gNB, i.e. for a RRC INACTIVE UE, the gNB could use this information to first page the UE according to the given SSB(s) in the gNB-DU. The gNB-CU may also include this information that is able to identify the last serving/most probable SSB(s) in the cell in the gNB-DU to the Core Network. The Core Network will store the information together with the UE identity, e.g. 5G-TMSI, and send it back to gNB upon the CN paging. The gNB could use this information to first page the UE corresponding to the given SSB(s) in the gNB-DU. Other assistance information may also be exchanged between said entities as further described herein. [0014] According to one aspect, a method performed by a first network node serving a cell in a radio access network (RAN) for paging a user equipment (UE) is provided. The method includes obtaining information from a second network node indicating a location of the UE within a cell served by the first network node associated with the UE. The method includes identifying, from a full set of areas in the cell served by the first network node, a subset of areas based on the obtained information. The method includes generating a paging transmission within the identified subset of areas or the full set of areas. The method includes transmitting the paging transmission towards the UE.

[0015] In some embodiments, the information comprises one or more Synchronization Signal Blocks (SSBs) indices and an identifier of the cell.

[0016] In some embodiments, the information comprises a SSB, a set of SSBs, or a SSB and timing advance information associated with a connection of the UE during a connection release procedure.

[0017] In some embodiments, the first network node is a gNB-DU and the second network node is a gNB-CU.

[0018] In some embodiments, the information is stored in the gNB-CU.

[0019] In some embodiments, the first network node is a gNB-CU and the second network node is a mobility management function (AMF) of the RAN. In some embodiments, the information is stored in the AMF. In some embodiments, the method further includes transmitting the information towards the AMF of the RAN and receiving a message comprising the information from the AMF. In some embodiments, the method further includes transmitting the information towards the AMF in response to a release of a connection of the UE. In some embodiments, the method further includes receiving the message comprising the information from the AMF upon paging of the UE.

[0020] In some embodiments, the obtaining comprises receiving a message from a second network node different than the first network node, wherein the message comprises the information.

[0021] In some embodiments, the network node stores the information as served Synchronization Signal Block (SSB) information when the UE is released.

[0022] In some embodiments, the method includes determining whether to generate a paging transmission within the identified subset of areas or the full set of areas, wherein the generating the transmission is based on the determining. In some embodiments, the determining is based on the information.

[0023] In some embodiments, the information further comprises one or more of: paging response statistics for the UE, mobility history of the UE, or type of the UE.

[0024] In another aspect, a method performed by a first network node serving a cell in a radio access network (RAN) for paging a user equipment is provided. The method includes transmitting a first message towards a second network node, the first message comprising information indicating a location of the UE within a cell served by the first network node associated with the UE. The method includes receiving a second message from the second network node, wherein the second message comprises the information and an instruction to page the UE.

[0025] In some embodiments, the first network node is a gNB-DU or gNB-CU and the second network node is a mobility management function (AMF) of the RAN.

[0026] In some embodiments, the method further includes identifying, from a full set of areas in the cell served by the first network node, a subset of areas based on the information; determining whether to generate a paging transmission within the identified subset of areas or the full set of areas; generating a paging transmission within the identified subset of areas or the full set of areas based on the determining; and transmitting the paging transmission towards the UE. In some embodiments, the determining is based on the information.

[0027] In some embodiments, the transmitting the first message is in response to a release of the UE.

[0028] In some embodiments, the information comprises one or more Synchronization Signal Blocks (SSBs) indices and an identifier of the cell.

[0029] In some embodiments, the information comprises a Synchronization Signal Block (SSB), a set of SSBs, or an SSB and timing advance information associated with a connection of the UE during a connection release procedure.

[0030] In some embodiments, the information further comprises one or more of: paging response statistics for the UE, mobility history of the UE, or type of the UE.

[0031] In some embodiments, the method further includes transmitting a third message towards a third network node, the third message comprising the information.

[0032] In another aspect there is provided a network node with processing circuitry adapted to perform the methods described above. In another aspect there is provided a computer program comprising instructions which when executed by processing circuity of a network node causes the network node to perform the methods described above. In another aspect there is provided a carrier containing the computer program, where the carrier is one of an electronic signal, an optical signal, a radio signal, and a computer readable storage medium.

BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The accompanying drawings, which are incorporated herein and form part of the specification, illustrate various embodiments.

[0034] FIG. 1 illustrates a NG-RAN node architecture.

[0035] FIG. 2 illustrates a core network paging procedure.

[0036] FIG. 3 illustrates a RAN paging procedure.

[0037] FIG. 4 illustrates a network consisting of three cells, according to some embodiments.

[0038] FIG. 5 illustrates a signaling diagram, according to some embodiments.

[0039] FIG. 6 illustrates a signaling diagram, according to some embodiments.

[0040] FIG. 7 illustrates a method, according to some embodiments.

[0041] FIG. 8 illustrates a method, according to some embodiments.

[0042] FIG. 9 a block diagram of a network node, according to some embodiments.

DETAILED DESCRIPTION

[0043] Aspects of the present disclosure relate to methods and interfaces in the RAN (gNB) and CN (AMF) for paging procedures.

[0044] In some embodiments, the NW stores one or more of the following information about the UE related to paging: (a) SSB which the UE connection was associated to during connection release to RRC IDLE/INACTIVE; (b) Paging response statistics for the UE, such as whether the UE historically has responded to the first paging attempt or whether more attempts/paging escalations in more beams/cells have been used before successful paging response; (c) Mobility history of the UE, such as whether the UE is static (e.g., Fixed Wireless Access type of device), or mobile (i.e., moving around in various beams/SSBs), and potentially including more information such as typical time UE spends in one or more beams/cells. In some embodiments, the information could be retrieved/reported from the UE, or derived by the NW itself based on keeping track of UE movements during various connections, or derived from subscription information; (d) Type of the UE, such as whether the UE tolerates potential delay in case of paging and potentially including a delay tolerance threshold.

[0045] In some embodiments, the information identified above may be stored in the NG-RAN e.g., in the gNB-CU in the UE context and/or in the CN (e.g., AMF).

[0046] In some embodiments, the information is sent from the RAN to the CN upon releasing the connection of the UE to RRC IDLE.

[0047] In some embodiments, upon paging of a UE in RRC IDLE, the CN may provide the information to a RAN.

[0048] In some embodiments, upon paging of a UE in RRC INACTIVE, the information is sent from a first RAN node to a second RAN node, in case the information is available in a UE context stored in a first RAN node.

[0049] In some embodiments, upon paging, the RAN based on the information chooses to narrow down paging transmission within fewer than all beams corresponding to the SSBs configured in the cell according to the information. This may be relevant in case the UE typically stays within the area (one or more beams) according to the stored information within the cell during the period of time currently relevant at the time of paging.

[0050] In some embodiments, upon paging, the RAN based on the information chooses to not narrow down paging transmission to only correspond to the SSBs according to the stored information. This may be relevant in case the UE, according to the information, typically moves from the same location (one or more beams) within the cell during the period of time currently relevant at the time of paging or the UE has historically not responded to the paging message in the first attempt.

[0051] In some embodiments, upon paging, the RAN based on said information chooses to not narrow down paging transmission to only correspond to the SSBs according to stored information in case the UE is of a certain type not tolerating a potential paging delay or not tolerating a potential delay beyond a specified threshold to which the gNB cannot conform to by paging in a narrowed down fashion.

[0052] It is also possible that instead of sending and storing the information in the gNB-CU/AMF UE context, the DU stores information correlated to information where the UE was released. This could be an SSB but also a set of SSBs or an SSB and timing advance information etc. Note that currently, when the UE is released or put into INACTIVE state, the UE context in the DU is released. This may be changed and may require assistance information to first identify the correct gNB-DU.

[0053] Several advantages may be achieved by the embodiments disclosed herein. For example, if the paging is narrowed down to a smaller set of SSBs in the cell, e.g. to the last served SSBs, less radio resources need to be utilized. The benefit of less resource utilization is both reduction of the network energy consumption and freed up resources for increased paging capacity without penalty to the time required to deliver the paging message to the UE.

[0054] With the knowledge that the UE is stationary, and the network knows the SSB where the UE is located, the network, with high probability, only needs to page one of the SSBs defining the cell. This results in better network energy efficiency and capacity.

[0055] Information about the UE location with higher accuracy when released to RRC Inactive enables the network to better predict the UE location when it is time to page the UE if the UE is not stationary. Better prediction results in less paging resources needed which results in better network energy efficiency and network capacity

[0056] The DU can optionally use a version parameter of its current configuration to understand if received information stored in the CU-CP or in the core network is valid or needs to be ignored [0057] In one embodiment, gNB-DU provides the serving SSB information to gNB-CU, e.g. during UE context release procedure. It may be one SSB or a list of SSBs. Table 1 below shows an example to include the Served SSB information in UE CONTEXT RELEASE COMPLETE in TS 38.473, in the direction from the gNB-DU towards the gNB-CU.

Table 1

[0058] The serving SSB information consists of Cell ID + one or more SSB Index/indices, to uniquely identify the SSB(s) in the DU. When using NR CGI as Cell ID, it is globally identified. The serving SSB information may be defined as an ASN.1 Octet string over Fl AP or other ASN.1 set of information elements. Table 2 below shows an example to define the Served SSB Information as OCTET STRING consisting of Cell ID + SSB ID.

Table 2

[0059] In one embodiment, gNB-CU stores the serving SSB information. The gNB-DU ID may be stored together so the gNB-CU may easily sort out later to which gNB-DU to send the paging message . The serving SSB is kept as gNB-DU ID + Cell ID + SSB Index/indices. Table 3A below illustrates an example to define the Served SSB information as an OCTET STRING, which consists of gNB-DU ID + Cell ID + SSB ID.

Table 3A

[0060] Table 3B below illustrates an example to define the Served SSB Information related as gNB ID and the OCTET STRING, which consists of Cell ID + SSB ID. In this example a list of the SSB’s information is included.

Table 3B

[0061] In one embodiment, the gNB-CU provides the serving SSB information to the Core Network, e.g. during a UE context release procedure. In this embodiment, the information element is defined as “RAN assistance information.” Table 4 below illustrates an example to include the “RAN assistance information” in UE CONTEXT RELEASE COMPLETE in TS 38.413. The direction is from the NG-RAN node towards the AMF.

Table 4

[0062] In some embodiments, the serving SSB information might be defined as an Abstract Syntax Notation One (ASN.1) Octet string or other set of ASN.1 information elements over NGAP which may or may not be transparent to the Core Network, for example it could be the length of NR CGI + SSB Index. Table 5 below shows an example to define the “RAN Assistance Information” as OCTET STRING, which consists of NR CGI + SSB ID. Table 5

[0063] In some embodiments, the gNB ID maybe included together for the AMF to easily identify the gNB when sending the paging message. Table 6A shows an example to define the “RAN Assistance Information” as OCTET STRING, which consists of gNB-ID + gNB-DU ID+ Cell ID + SSB ID.

Table 6A

[0064] Table 6B below shows an example to define the “RAN assistance information” related as gNB ID and the OCTET STRING, which consists of gNB+DU + Cell ID + SSB ID. In this example a list of the SSB’s information is included.

Table 6B [0065] In one embodiment, the CN includes the serving SSB information stored together with the UE identify (e.g. 5G-TMSI) when it pages the UE to gNB. The information can be conveyed in Paging message. Table 7 illustrates an example to include the RAN Assistance Information in TS 38.413. The direction of the information is from the AMF towards the NG-RAN node.

Table 7

[0066] In yet another embodiment, the gNB-CU includes the serving SSB information to the gNB- DU when paging the UE. The gNB-DU should then use the information to perform paging. Table 8 shows an example to include the “Served SSB information” in TS 38.473, where the direction of the information is from the gNB-CU towards the gNB-DU.

Table 8

[0067] A similar approach over XnAP may be used for the UEs involved in DC.

[0068] In one embodiment, when the information is stored/updated in the UE context within a first RAN node (e.g., first gNB-CU), the information my further be sent over the XnAP to a second RAN node (second gNB-CU). In such case, each RAN node may add its information related to UEs paging behavior, such as last/typical SSB connection. Once a UE is to be paged from a RAN node, the RAN node may then fetch said information relevant to its node from the UE context and use it for deciding whether to page the UE in all beams of a cell hosted by this RAN node.

[0069] In one embodiment, gNB-DU provides a parameter denoted “m” indicative of the UE location in the cell, e.g. in the UE context release procedure. The parameter m may only have any meaning to the DU. Examples of information indicative of the location may include serving SSB, timing advance, measurement on neighboring cells, etc.

[0070] In one embodiment, the parameter denoted m may be indicative of other paging related information, such as: (a) Paging response statistics for the UE. Whether the UE historically has responded to the first paging attempt or whether more attempts/paging escalations in more beams/cells have been used before successful paging response. Said information may in one embodiment be formed based on input from both RAN and CN. (b) Mobility history of the UE; whether the UE is static (e.g., Fixed Wireless Access type of device), or mobile (i.e., moving around in various beams/SSBs) potentially including more information such as typical time UE spends in one or more beams/cells. Where said information could be retrieved/reported from the UE, or derived by the NW (RAN and/or CN) itself based on keeping track of UE movements during various connections, or derived from subscription information, (c) Type of the UE, whether the UE tolerates potential delay in case of paging. Potentially including a delay tolerance threshold. This information may either be retrieved by the NW (e.g. CN) based on UE’s subscription information/SLA, or reported by the UE via assistance information.

[0071] In one embodiment, gNB-CU stores the parameter m for the UE. gNB-DU ID may be stored together so gNB-CU could easily sort out later to which gNB-DU to send the paging message.

[0072] The parameter m might be defined as octet string over F1AP and transparent to the CU- CP.

[0073] In one embodiment, gNB-CU includes the parameter m to Core Network, e.g. during UE context release procedure.

[0074] The parameter m might be defined as octet string over NGAP and transparent to the core network.

[0075] In one embodiment, CN includes the parameter m stored together with the UE identity (e.g. 5G-TMSI) when it pages the UE to gNB. The information can be conveyed in a Paging message. [0076] In yet another embodiment, gNB-CU includes the parameter m to the gNB-DU when page the UE. gNB-DU should use the information to perform paging.

[0077] In addition to the parameter m the DU can have an indicator “v” indicative of the version of the current configuration in the DU indicative of when the parameter m is valid.

[0078] In one embodiment the DU provides the indicator v together with the parameter m to the CU-CP.

[0079] In one embodiment the CU-CP provides the indicator v together with the parameter m to the A MF.

[0080] In one embodiment when the DU receives a parameter m and the associated configuration parameter v the DU can compare the received configuration parameter v with a current configuration parameter vc in use. If the parameter v and parameter vc are different they DU may realize that the parameter m is not reliable and is ignored and the DU pages the UE as if the parameter m was not present.

[0081] In one embodiment the DU combines the parameters v and vc are put in the same information element e.g. an octet string when sending this information over the Fl AP.

[0082] In yet another embodiment, the NG-RAN node may estimate the UE position and decide to narrow down to page the UE in the expected area, using the information described here and other available information. FIG. 4 illustrates a network consisting of three cells cl, c2 and c3, where the cell cl has two location areas ml and m2 indicative of location. When the UE is released into an area the network can then, when the UE resumes, learn where the UE resumes e.g. in which cell the UE resumes or possibly area mi for that cell. FIG. 4 illustrates that, with the knowledge that the UE is released in cell cl, it moves to cell c2 with probability pl l. However, with the more accurate information that the UE is released in area ml in cell cl, the probability to move to the area with p2,ml may be estimated. According to FIG. 4, pl 1 and p2, ml are related by the expression pl l = p _mi pi, mi + p _m 2 pi, m2 hence normally they are different. One may get better predictions on the UE location when it is to be paged by learning where the UE moves in the network, taking into account the finer granularity. With the better understanding of where the UE was released more accurate predictions may be obtained on where the UE has moved. When a node pages the most probable cells first, less cells will on average be paged hence energy consumption in the network is reduced. [0083] In the embodiments disclosed herein, upon paging, the RAN, based on said information, chooses to narrow down paging transmission within fewer than all beams corresponding to the SSBs configured in the cell according to said information. This step is relevant in case the UE according to said stored information typically stays within the area (one or more beams) according to said stored information within the cell during the period of time currently relevant at the time of paging. The RAN based on said information may instead choose to not narrow down paging transmission to only correspond to the SSBs according to stored information. This step is relevant in case the UE according to said information typically moves away from the same location (one or more beams) within the cell during the period of time currently relevant at the time of paging or the UE has historically not responded to the paging message in the first attempt. In addition, the RAN based on said information, may choose to not narrow down paging transmission to only correspond to the SSBs according to stored information in case the UE is of a certain type not tolerating a potential paging delay or not tolerating a potential delay beyond a specified threshold to which the gNB cannot conform to by paging in narrowed down fashion considering the risk that the UE may not be found in that paging beam and the gNB has to wait for the next paging cycle to expand paging area.

[0084] FIG. 5 illustrates a signaling diagram, according to some embodiments. FIG. 5 illustrates a procedure where different nodes are involved, including a gNB-DU 506, gNB-CU 508, and an AMF 504. At 501, the gNB-DU serves information indicating a location of a UE at a time of release of the UE. FIG. 5 illustrates an example where the information may include served SSB information at the release. At 503, the gNB-CU stores the SSB information if the UE context is kept (e.g., at RRC Inactive). At 505, the gNB-CU sends the SSB information to the AMF. At 507, the AMF stores the SSB information for the UE. At 509 the UE is released to idle or to RRC Inactive, until it is paged. At 511, the AMF sends a page message towards the gNB-CU, and the page message includes the SSB information stored at 507. At 513, the gNB-CU transmits a page message towards the gNB-DU, and the page message includes the SSB information. At 515, the gNB-DU uses the information for efficient paging to achieve energy saving as described herein.

[0085] FIG. 6 illustrates a signaling diagram, according to some embodiments. FIG. 6 illustrates a procedure among an AMF 604, gNB-CU 608, and gNB-DU 606 where the SSB information is stored in the NG-RAN node, e.g., for a RRC -Inactive UE. At 601, the AMF transmits a paging message towards the gNB-CU. At 603, the gNB-CU obtains stored information for the RRC- Inactive UE, and the gNB-CU may use the information stored to estimate the possible best location to page the UE. At 605, the gNB-CU initiates a paging message towards the gNB-DU 606 over the Fl interface, including the SSB information. At 607, the gNB-DU uses the SSB information for efficient paging to achieve energy saving as described herein.

[0086] FIG. 7 illustrates a method, according to some embodiments. In some embodiments, method 700 is a computer-implemented method performed by a network node serving a cell in a radio access network (RAN) for paging a user equipment (UE).

[0087] Step s701 of the method includes obtaining information identifying one or more Synchronization Signal Blocks (SSB) within the cell served by the first network node associated with the UE.

[0088] Step s703 of the method includes identifying, from a full set of areas in the cell served by the first network node, a subset of areas based on the obtained information. In some embodiments, the areas in the cell are Synchronization Signal Blocks.

[0089] Step s705 of the method includes generating a paging transmission within the identified subset of areas or the full set of areas.

[0090] Step s707 of the method includes transmitting the paging transmission towards the UE.

[0091] FIG. 8 illustrates a method, according to some embodiments. In some embodiments, method 800 is performed by a first network node serving a cell in a radio access network (RAN) for paging a user equipment (UE).

[0092] Step 801 of the method includes transmitting a first message towards a second network node, the first message comprising information indicating a location of the UE within a cell served by the first network node associated with the UE.

[0093] Step 803 of the method includes receiving a second message from the second network node, wherein the second message comprises the information and an instruction to page the UE.

[0094] FIG. 9 is a block diagram of a network node 900 according to some embodiments. As shown in FIG. 9, the network node may comprise: processing circuitry (PC) 902, which may include one or more processors (P) 955 (e.g., one or more general purpose microprocessors and/or one or more other processors, such as an application specific integrated circuit (ASIC), field- programmable gate arrays (FPGAs), and the like); communication circuitry 948, comprising a transmitter (Tx) 945 and a receiver (Rx) 947 for enabling the device to transmit data and receive data (e.g., wirelessly transmit/receive data) over network 910; and a local storage unit (a.k.a., “data storage system”) 908, which may include one or more non-volatile storage devices and/or one or more volatile storage devices. In embodiments where PC 902 includes a programmable processor, a computer program product (CPP) 941 may be provided. CPP 941 includes a computer readable medium (CRM) 942 storing a computer program (CP) 943 comprising computer readable instructions (CRI) 944. CRM 942 may be a non-transitory computer readable medium, such as, magnetic media (e.g., a hard disk), optical media, memory devices (e.g., random access memory, flash memory), and the like. In some embodiments, the CRI 944 of computer program 943 is configured such that when executed by PC 902, the CRI causes the apparatus to perform steps described herein (e.g., steps described herein with reference to the flow charts). In other embodiments, the apparatus may be configured to perform steps described herein without the need for code. That is, for example, PC 902 may consist merely of one or more ASICs. Hence, the features of the embodiments described herein may be implemented in hardware and/or software. [0095] Summary of Various Embodiments

[0096] 1. A method (700) performed by a first network node (900) serving a cell in a radio access network (RAN) for paging a user equipment (UE), the method comprising: obtaining (s701) information from a second network node indicating a location of the UE within a cell served by the first network node associated with the UE; identifying (s703), from a full set of Synchronization Signal Blocks (SSBs) in the cell served by the first network node, a subset of SSBs based on the obtained information; generating (s705) a paging transmission within the identified subset of SSBs or the full set of SSBs; and transmitting (s707) the paging transmission towards the UE.

[0097] 2. The method of embodiment 1 , wherein the information comprises one or more SSBs indices and an identifier of the cell.

[0098] 3. The method of any one of embodiments 1-2, wherein the information comprises a SSB associated with a connection of the UE during a connection release procedure.

[0099] 4. The method of any one of embodiments 1-3, wherein the first network node is a gNB-DU and the second network node is a gNB-CU.

[00100] 5. The method of embodiment 4, wherein the information is stored in the gNB-CU. [00101] 6. The method of any one of embodiments 1-4, wherein the first network node is a gNB-CU or a gNB-DU and the second network node is a mobility management function (AMF) of the RAN.

[00102] 7. The method of embodiment 6, wherein the information is stored in the

AMF.

[00103] 8. The method of any one of embodiments 6-7, further comprising: transmitting the information towards the AMF of the RAN; and receiving a message comprising the information from the AMF.

[00104] 9. The method of embodiment 8, further comprising: transmitting the information towards the AMF in response to a release of a connection of the UE. [00105] 10. The method of any one of embodiments 8-9, further comprising: receiving the message comprising the information from the AMF upon paging of the UE. [00106] 11. The method of any one of embodiments 1-10, wherein the obtaining comprises receiving a message from a second network node different than the first network node, wherein the message comprises the information.

[00107] 12. The method of any one of embodiments 1-11, wherein the network node stores the information as served SSB information when the UE is released.

[00108] 13. The method of any one of embodiments 1-12, further comprising: determining whether to generate a paging transmission within the identified subset of SSBs or the full set of SSBs, wherein the generating the transmission is based on the determining.

[00109] 14. The method of embodiment 13, wherein the determining is based on the information.

[00110] 15. The method of any one of embodiments 1-14, wherein the information further comprises one or more of: paging response statistics for the UE, mobility history of the UE, or type of the UE.

[00111] 16. A method (800) performed by a first network node (900) serving a cell in a radio access network (RAN) for paging a user equipment (UE), the method comprising: transmitting (801) a first message towards a second network node, the first message comprising information indicating a location of the UE within a cell served by the first network node associated with the UE; and receiving (803) a second message from the second network node, wherein the second message comprises the information and an instruction to page the UE.

[00112] 17. The method of embodiment 16, wherein the first network node is a gNB-

DU or gNB-CU and the second network node is a mobility management function (AMF) of the RAN.

[00113] 18. The method of any one of embodiments 16-17, further comprising: identifying, from a full set of Synchronization Signal Blocks (SSBs) in the cell served by the first network node, a subset of SSBs based on the information; determining whether to generate a paging transmission within the identified subset of SSBs or the full set of SSBs; generating a paging transmission within the identified subset of SSBs or the full set of SSBs based on the determining; and transmitting the paging transmission towards the UE.

[00114] 19. The method of embodiment 18, wherein the determining is based on the information.

[00115] 20. The method of any one of embodiments 16-19, wherein the transmitting the first message is in response to a release of the UE.

[00116] 21. The method of any one of embodiments 16-20, wherein the information comprises one or more SSBs indices and an identifier of the cell.

[00117] 22. The method of any one of embodiments 16-21, wherein the information comprises a SSB associated with a connection of the UE during a connection release procedure.

[00118] 23. The method of any one of embodiments 16-22, wherein the information further comprises one or more of: paging response statistics for the UE, mobility history of the UE, or type of the UE.

[00119] 24. A network node (900), wherein the network node is adapted to perform the method of any one of embodiments 1-23. 1 [00120] 25. A computer program (943) comprising instructions (944) which when executed by processing circuity (902) of a network node (600) causes the network node to perform the method of any one of embodiments 1-23.

[00121] 26. A carrier containing the computer program of embodiment 25, wherein the carrier is one of an electronic signal, an optical signal, a radio signal, and a computer readable storage medium (642).

[00122] While various embodiments are described herein, it should be understood that they have been presented by way of example only, and not limitation. Thus, the breadth and scope of this disclosure should not be limited by any of the above described embodiments. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the disclosure unless otherwise indicated herein or otherwise clearly contradicted by context.

[00123] Additionally, while the processes described above and illustrated in the drawings are shown as a sequence of steps, this was done solely for the sake of illustration. Accordingly, it is contemplated that some steps may be added, some steps may be omitted, the order of the steps may be re-arranged, and some steps may be performed in parallel.

[00124] ABBREVIATIONS

[00125] AMF 5G Access and Mobility Management Function

[00126] CN Core Network

[00127] gNB-CU gNB Central Unit (CU)

[00128] gNB-DU gNB Distributed Unit (DU)