Providing measurement data for locating inactive user equipment

Abstract

According to one aspect, there is provided a solution in which a radio access network using Layer 1 / Layer 2 triggered mobility LTM may use a latest L1 measurement of a prepared cell received from a particular user equipment to better identify a latest user equipment location when performing radio access network paging. A first network node supporting at least one of a central unit control plane (CU-CP) function or a Layer 3 protocol of a wireless access network may establish a connection towards a user equipment and receive information related to Layer 1 measurements performed by the user equipment.

Description

Technical Field

[0001] Various example embodiments generally relate to the field of telecommunications systems. In particular, some example embodiments relate to solutions for locating inactive user equipment in a radio access network. Background Technology

[0002] User equipment (UE) can be in an RRC-inactive (RRC, Radio Resource Control) state in a wireless communication network, such as a 5G network. In the RRC-inactive state, the UE is in a CM-connected (CM, Connection Management) state and can move within the area, i.e., it is notified of the RAN-based notification area (RAN) configured by the RAN, without notifying the RAN. In the RRC-inactive state, the last serving gNB node maintains the UE context and the NG connections associated with the UE for Serving Access and Mobility Management (AMF) and User Plane Function (UPF).

[0003] If the last serving gNB subsequently receives downlink (DL) data from the UPF or DL ​​UE-related signaling from the AMF while the UE is in an RRC_inactive state, the last serving gNB will page the UE in the cell corresponding to the RAN-based notification area (RNA), and if the RNA includes cells of (multiple) neighboring gNBs, the last serving gNB may send an XnAP RAN paging to (multiple) neighboring gNBs. This paging is referred to as a RAN paging.

[0004] A RAN can be configured with multiple cells. When an RNA is configured with multiple cells, the UE will not perform many RNA updates (RNAUs), and in the case of incoming traffic, it can be quickly located by paging all or almost all cells. On the other hand, if the RNA is a small set of cells, few cells need to be paged to locate the UE. However, the UE needs to send RNAUs frequently because it will frequently cross RNA boundaries. Therefore, several strategies exist to locate the UE more quickly, for example, by defining small RNAs that cause frequent RNAUs to the UE, or defining large RNAs that cause paging to all cells or delays in UE location. However, these strategies have the disadvantage of generating significant overhead or delaying the paging process. Summary of the Invention

[0005] This invention is provided to introduce, in a simplified form, various concepts that will be further described in the detailed description below. This overview is not intended to identify key or essential features of the claimed subject matter, nor is it intended to limit the scope of the claimed subject matter.

[0006] The exemplary embodiments disclosed herein provide a solution in which more efficient paging of user equipment can be provided. This and other benefits can be achieved through the features of the independent claims. Further exemplary embodiments are provided in the dependent claims, the specification, and the drawings.

[0007] According to the first aspect, a first network node supporting at least one of the Central Unit Control Plane (CU-CP) function or Layer 3 protocol of a wireless access network may include at least one processor and at least one memory storing instructions, which, when executed by the at least one processor, cause the first network node to at least: establish a connection toward a user equipment; and receive information related to a Layer 1 measurement performed by the user equipment.

[0008] In an example embodiment of the first aspect, the information related to the layer 1 measurement includes an associated time window indicating the validity of the provided measurement results, and / or an associated validity timer, and / or associated timing information.

[0009] In an example embodiment of the first aspect, the instructions, when executed by at least one processor, cause the first network node to perform: sending a message that triggers the provision of information related to layer 1 measurements.

[0010] In an example embodiment of the first aspect, the instructions, when executed by at least one processor, cause the first network node to perform: start a validity timer for layer 1 measurements.

[0011] In an example embodiment of the first aspect, the Layer 1 measurement includes: Layer 1 measurements received from a source network node of at least one of a Central Unit Control Plane (CU-CP) function or a Layer 3 protocol supporting a radio access network and from a target network node of at least one of a Distributed Unit (DU) function or a Layer 2 protocol supporting a radio access network.

[0012] In an example embodiment of the first aspect, when the instructions are executed by at least one processor, the first network node performs: retrieves a UE context response message and receives a Layer 1 measurement from a source network node, the source network node supporting at least one of the Central Unit Control Plane (CU-CP) functions or Layer 3 protocols of the radio access network.

[0013] In an example embodiment of the first aspect, the instructions, when executed by at least one processor, cause the first network node to perform: receiving a Layer 3 measurement associated with a user equipment having a RAN notification area update message.

[0014] In an example embodiment of the first aspect, when executed by at least one processor, the instructions cause the first network node to perform: receiving incoming traffic for the user equipment; and paging the user equipment according to a paging scheme associated with Layer 1 measurements.

[0015] In an example embodiment of the first aspect, the instructions, when executed by at least one processor, cause a first network node to perform: paging the last serving cell of a user equipment and the cell indicated in a configurable number of last measurements.

[0016] In an example embodiment of the first aspect, when executed by at least one processor, the instructions cause a first network node to perform: identifying a mobility mode of a user equipment; and a paging cell associated with the mobility mode.

[0017] In an example embodiment of the first aspect, the instructions, when executed by at least one processor, cause the first network node to perform: paging the last serving cell of the user equipment and a subset of cells indicated in the Layer 1 measurement.

[0018] In an example embodiment of the first aspect, the instructions, when executed by at least one processor, cause the first network node to perform: select a set of beams for each identified cell based on layer 1 measurements.

[0019] In an example embodiment of the first aspect, when executed by at least one processor, the instructions cause a first network node to perform: sending a layer 1 measurement to a target network node that supports at least one of the central unit control plane (CU-CP) functions or layer 3 protocols of a radio access network.

[0020] According to the second aspect, a second network node supporting at least one of the Distributed Unit (DU) function or a Layer 2 protocol of a radio access network may include: at least one processor; and at least one memory storing instructions, which, when executed by the at least one processor, cause the second network node to at least: establish a connection toward a user equipment; receive a Layer 1 / Layer 2 triggered Mobility Module (LTM) configuration message from a first network node supporting at least one of the Central Unit Control Plane (CU-CP) function or a Layer 3 protocol of a radio access network, the Layer 1 / Layer 2 triggered Mobility Module (LTM) configuration message instructing the second network node to operate in LTM and monitor Layer 1 measurements performed by and received from the user equipment; and send information related to the received Layer 1 measurements to the first network node.

[0021] In an example embodiment of the second aspect, the information related to the received Layer 1 measurement includes: an associated time window indicating the validity of the provided measurement result, and / or an associated validity timer, and / or associated timing information.

[0022] In an example embodiment of the second aspect, when executed by at least one processor, the instructions cause the second network node to: receive a Radio Resource Control (RRC) release message from the first network node, the RRC message being forwarded to the user equipment, thereby instructing the user equipment to operate in an inactive state, wherein a request for providing information related to Layer 1 measurements is received along with the RRC release message.

[0023] In an example embodiment of the second aspect, when executed by at least one processor, the instructions cause the second network node to: send an LTM cell change trigger message to the user equipment; and send a message to the first network node indicating the triggered LTM cell change and including information related to Layer 1 measurements.

[0024] According to the third aspect, a first network node supporting at least one of the Central Unit Control Plane (CU-CP) functions or Layer 3 protocols of a wireless access network may include: at least one processor; and at least one memory storing instructions, which, when executed by the at least one processor, cause the first network node to at least: send a Layer 1 measurement associated with a user equipment, and the user equipment to perform a Layer 1 / Layer 2 triggered mobility (LTM) operation.

[0025] In an example embodiment of the third aspect, when the instruction is executed by at least one processor, it causes a first network node to perform: sending a Layer 1 measurement to a target network node using a retrieve UE context response message, the target network node supporting at least one of the Central Unit Control Plane (CU-CP) functions or Layer 3 protocols of the radio access network.

[0026] In an example embodiment of the third aspect, the instructions, when executed by at least one processor, cause the first network node to perform: in response to receiving a handover success message, send the Layer 1 measurement to a target network node that supports at least one of the Central Unit Control Plane (CU-CP) functions or Layer 3 protocols of the radio access network.

[0027] According to the fourth aspect, a user equipment operating in an inactive state may include: at least one processor; and at least one memory storing instructions, which, when executed by the at least one processor, cause the user equipment to at least: establish a connection to a first network node, the first network node supporting at least one of a Central Unit Control Plane (CU-CP) function or a Layer 3 protocol of a radio access network; receive from the first network node a message including instructions indicating inactive operation; and, when operating in an inactive state, send a Radio Resource Control (RRC) recovery request message, the message including information related to at least one measurement performed by the user equipment.

[0028] In an example embodiment of the fourth aspect, the information relates to layer 1 and / or layer 3 measurements performed by the user equipment.

[0029] According to the fifth aspect, a method is performed by a first network node that supports at least one of a central unit control plane (CU-CP) function or a layer 3 protocol of a radio access network, the method comprising: establishing a connection toward a user equipment; and receiving information relating to a layer 1 measurement performed by the user equipment.

[0030] In an example embodiment of the fifth aspect, the information related to the layer 1 measurement includes: an associated time window indicating the validity of the provided measurement results, and / or an associated validity timer, and / or associated timing information.

[0031] In an example embodiment of the fifth aspect, the method further includes sending a message that triggers the provision of information related to layer 1 measurements.

[0032] In an example embodiment of the fifth aspect, the method further includes activating a validity timer for layer 1 measurements.

[0033] In an example embodiment of the fifth aspect, the Layer 1 measurement includes Layer 1 measurements received from a source network node of at least one of a Central Unit Control Plane (CU-CP) function or a Layer 3 protocol supporting a radio access network and from a target network node of at least one of a Distributed Unit (DU) function or a Layer 2 protocol supporting a radio access network.

[0034] In an example embodiment of the fifth aspect, the method further includes receiving from the source network node a retrieve UE context response message having at least one of Layer 1 measurements, the source network node supporting a Central Unit Control Plane (CU-CP) function or a Layer 3 protocol of the radio access network.

[0035] In an example embodiment of the fifth aspect, the method further includes: receiving a Layer 3 measurement associated with a user equipment having a RAN notification area update message.

[0036] In an example embodiment of the fifth aspect, the method further includes: receiving input traffic from a user equipment; and paging the user equipment according to a paging scheme associated with Layer 1 measurements.

[0037] In an example embodiment of the fifth aspect, the method further includes: paging the last serving cell of the user equipment and the cell indicated in a configurable number of last measurements.

[0038] In an example embodiment of the fifth aspect, the method further includes: identifying the mobility pattern of the user equipment; and paging the cell associated with the mobility pattern.

[0039] In an example embodiment of the fifth aspect, the method further includes: paging the last serving cell of the user equipment and a subset of cells indicated in the Layer 1 measurement.

[0040] In an example embodiment of the fifth aspect, the method further includes: selecting a set of beams for each identified cell based on layer 1 measurements.

[0041] In an example embodiment of the fifth aspect, the method further includes: sending a layer 1 measurement to a target network node that supports at least one of a central unit control plane (CU-CP) function or a layer 3 protocol of a wireless access network.

[0042] According to a sixth aspect, a method is performed by a second network node that supports at least one of a distributed cell (DU) function or a layer 2 protocol of a radio access network, the method comprising: establishing a connection toward a user equipment; receiving a layer 1 / layer 2 triggered mobility LTM configuration message from a first network node that supports at least one of a central cell control plane (CU-CP) function or a layer 3 protocol of the radio access network, the configuration message instructing the second network node to operate in LTM mode, and monitoring layer 1 measurements performed by and received from the user equipment; and sending information related to the received layer 1 measurements to the first network node.

[0043] In an example embodiment of the sixth aspect, the information related to the received Layer 1 measurement includes: an associated time window indicating the validity of the provided measurement result, and / or an associated validity timer, and / or associated timing information.

[0044] In an example embodiment of the fifth aspect, the method further includes: receiving a Radio Resource Control (RRC) release message from a first network node, the RRC message being forwarded to a user equipment to instruct the user equipment to operate in an inactive state, wherein a request for providing information related to Layer 1 measurements is received along with the RRC release message.

[0045] In an example embodiment of the fifth aspect, the method further includes sending an LTM cell change trigger message to a user equipment; and sending a message to a first network node indicating the triggered LTM cell change and including information related to Layer 1 measurements.

[0046] According to the seventh aspect, a method is performed by a first network node that supports at least one of a distributed unit (DU) function or a layer 3 protocol of a radio access network, the method comprising transmitting a layer 1 measurement associated with a user equipment operating in a layer 1 / layer 2 triggered mobility (LTM).

[0047] In an example embodiment of the seventh aspect, the method further includes sending a Layer 1 measurement to a target network node using a retrieve UE context response message. The target network node supports at least one of the Central Unit Control Plane (CU-CP) functions or Layer 3 protocols of the radio access network.

[0048] In an example embodiment of the seventh aspect, the method further includes: in response to receiving a handover success message, sending a layer 1 measurement to a target network node that supports at least one of a central unit control plane (CU-CP) function or a layer 3 protocol of a radio access network.

[0049] According to the eighth aspect, a method for operating a user equipment in an inactive state includes: establishing a connection toward a first network node, the first network node supporting at least one of a central unit control plane (CU-CP) function or a layer 3 protocol of a radio access network; receiving from the first network node a message including an instruction to operate in an inactive state; and, while operating in an inactive state, sending a radio resource control (RRC) recovery request message including information related to at least one measurement performed by the user equipment.

[0050] In an example embodiment of the eighth aspect, the information relates to layer 1 and / or layer 3 measurements performed by the user equipment.

[0051] According to a ninth aspect, a (non-transient) computer-readable medium is disclosed. The (non-transient) computer-readable medium may include program instructions that, when executed by a device, cause the device to perform a method according to the fifth, sixth, seventh, or eighth aspect or any example embodiment thereof.

[0052] According to the tenth aspect, a first network node supporting at least one of the Central Unit Control Plane (CU-CP) function or Layer 3 protocol of a wireless access network may include components for: establishing a connection toward a user equipment; and receiving information related to Layer 1 measurements performed by the user equipment.

[0053] According to the eleventh aspect, a second network node supporting at least one of the distributed unit (DU) function or layer 2 protocol of a radio access network may include components for: establishing a connection toward a user equipment; receiving a layer 1 / layer 2 triggered mobility (LTM) configuration message from a first network node supporting at least one of the central unit control plane (CU-CP) function or layer 3 protocol of the radio access network, the configuration message instructing the second network node to operate in LTM mode and monitor layer 1 measurements performed by and received from the user equipment; and sending information related to the received layer 1 measurements to the first network node.

[0054] According to the twelfth aspect, a first network node supporting at least one of the central unit control plane (CU-CP) function or layer 3 protocol of the radio access network may include components for: transmitting layer 1 measurements associated with user equipment operating in a mobility LTM triggered in layer 1 / layer 2.

[0055] According to the thirteenth aspect, a user equipment for operating in an inactive state may include components for: establishing a connection toward a first network node, the first network node supporting at least one of a central unit control plane (CU-CP) function or a layer 3 protocol of a radio access network; receiving from the first network node a message including an instruction to operate in an inactive state; and, when operating in an inactive state, sending a radio resource control (RRC) recovery request message including information related to at least one measurement performed by the user equipment.

[0056] Many of the accompanying features will be easier to understand as they become clearer with reference to the following detailed description taken in conjunction with the accompanying drawings. Attached Figure Description

[0057] The accompanying drawings, which are included to provide a further understanding of the exemplary embodiments and form part of this specification, illustrate exemplary embodiments and, together with the description, aid in understanding the exemplary embodiments. In the drawings:

[0058] Figure 1 An example of a split access node architecture is shown.

[0059] Figure 2A An example of a RAN-based notification area is shown.

[0060] Figure 2B Another example of a RAN-based notification area is shown.

[0061] Figure 3 An example of a device configured to practice one or more example embodiments is shown.

[0062] Figure 4 The concept of Layer 1 / Layer 2 triggered mobility (LTM) in a wireless access network is illustrated.

[0063] Figure 5A A signaling diagram according to an example embodiment is shown.

[0064] Figure 5B A signaling diagram according to another example embodiment is shown.

[0065] Figure 5C A signaling diagram according to another example embodiment is shown.

[0066] Figure 5D A signaling diagram according to another example embodiment is shown.

[0067] Figure 6 An example of a method according to an example embodiment is shown.

[0068] Figure 7 An example of a method according to another example embodiment is shown.

[0069] Figure 8 An example of a method according to another example embodiment is shown.

[0070] Figure 9 An example of a method according to another example embodiment is shown.

[0071] Figure 10 A signaling diagram according to an example embodiment is shown.

[0072] Figure 11 A signaling diagram according to another example embodiment is shown.

[0073] Figure 12 A signaling diagram according to another example embodiment is shown.

[0074] Figure 13 A signaling diagram according to another example embodiment is shown.

[0075] Figure 14 A signaling diagram according to another example embodiment is shown.

[0076] In the accompanying drawings, the same reference numerals are used to denote the same parts. Detailed Implementation

[0077] Reference will now be made in detail to exemplary embodiments, examples of which are illustrated in the accompanying drawings. The detailed description provided below, in conjunction with the drawings, is intended as a description of this example and not as representing the only form in which this example can be constructed or utilized. This description illustrates the function of the example and the sequence of steps for constructing and operating the example. However, the same or equivalent functions and sequences can be implemented through different examples.

[0078] Figure 1An example of a split access node architecture is illustrated. The access node, represented by gNB 100, can be functionally and / or physically split into a central unit (CU) 108 and one or more distributed units (DUs) 102-1, 102-2, ..., 102-N. CU 108 may also be referred to as gNB-CU, and DU may also be referred to as gNB-DU. CU 108 may include control plane (CP) and user plane (UP) entities, represented by gNB-CU-CP 104 and gNB-CU-UP 106, respectively. gNB-CU-CP 104 can be configured to communicate control signaling data that enables the transmission of user / application data on the user plane. User plane communication can be provided by one or more gNB-CU-UP 106 associated with gNB-CU-CP 104. CU 108 and DU can be configured to provide radio access network (RAN) services to a device represented by user equipment (UE) 110 in one or more cells.

[0079] The control and user plane entities of CU 108 can communicate via a communication interface, such as, for example, the E1 interface. CU 108 can also communicate with DU102-n (n=1…) via a communication interface (e.g., the F1 interface). N Communication. The F1 interface may include control and user plane interfaces (F1-C, F1-U) between the control and user plane entities of DU102-n and CU 108, respectively. DU 102-1 to 102-N can be collectively referred to as DU 102, where N is, for example, a positive integer ranging from 1 to 100. However, higher values, such as up to 2... 36 -1 is also possible.

[0080] The CU / DU split architecture allows for RAN decomposition, enabling operators to utilize different vendors for different network nodes and allowing network vendors to split their network implementations for scalability purposes. For example, the control and user planes can be split into their own entities, allowing control and user plane functions to be separately sized. However, the split may be (almost) invisible to the user equipment (UE), so on the UE side, the protocol layer may be (mostly) unaware of the split, except for a small portion that the UE can implicitly determine from the associated RRC configuration.

[0081] The following description provides further details on alternatives, modifications and changes: gNB includes, for example, nodes that provide NR user plane and control plane protocol termination to the UE, and, for example, nodes connected to the 5GC via the NG interface according to Section 3.2 of 3GPP TS 38.300 V16.6.0 (2021-06) which is covered by reference.

[0082] The gNB-CU 108 includes, for example, a logical node that hosts the RRC, SDAP, and PDCP protocols of the gNB or controls the operation of one or more gNB-DUs via the en-gNB's RRC and PDCP protocols. The gNB-CU 108 terminates the F1 interface connected to the gNB-DU.

[0083] gNB-DU 102-1, 102-2, and 102-N include, for example, logical nodes at the RLC, MAC, and PHY layers that host a gNB or en-gNB, and whose operation is partially controlled by the gNB-CU. One gNB-DU supports one or more cells. A cell is supported by only one gNB-DU. The gNB-DU terminates at the F1 interface connected to the gNB-CU.

[0084] gNB-CU-CP 104 includes, for example, a logical node for an en-gNB or gNB, which hosts the RRC and control plane portions of the PDCP protocol for gNB-CU, for example. gNB-CU-CP 104 terminates the E1 interface connected to gNB-CU-UP 106 and the F1-C interface connected to gNB-DU.

[0085] gNB-CU-UP 106 includes, for example, a logical node that hosts, for example, the user plane portion of the PDCP protocol for the gNB-CU of the en-gNB, and the user plane portions of the PDCP and SDAP protocols for the gNB-CU of the gNB. gNB-CU-UP 106 terminates the E1 interface connected to gNB-CU-CP 104 and the F1-U interface connected to gNB-DU, as covered by reference, for example, to Section 3.1 of 3GPP TS 38.401 V16.6.0 (2021-07).

[0086] Different functional divisions between central and distributed units are possible, for example, referred to as options:

[0087] Option 1 (Class 1A split): The functional breakdown in this option is similar to the 1A architecture in a DC. RRC is in the central unit. PDCP, RLC, MAC, physical layer, and RF are in the distributed units.

[0088] Option 2 (3C-like split): The functional breakdown in this option is similar to the 3C architecture in a DC (Distributed Control) module. RRC and PDCP are in the central unit. RLC, MAC, physical layer, and RF are in distributed units.

[0089] Option 3 (Internal RLC Splitting): Low RLC (partial RLC functionality), MAC, physical layer, and RF are located in the distributed unit. PDCP and high RLC (the remaining RLC functionality) are located in the central unit.

[0090] Option 4 (RLC-MAC split): The MAC, physical layer, and RF are located in the distributed unit. PDCP and RLC are located in the central unit.

[0091] Alternatively, for example, according to section 11 of 3GPP TR 38.801 V14.0.0 (2017-03) which is covered by reference.

[0092] gNB supports different protocol layers, such as Layer 1 (L1) - the physical layer.

[0093] NR's Layer 2 (L2) is broken down into the following sublayers: Media Access Control (MAC), Radio Link Control (RLC), Packet Data Convergence Protocol (PDCP), and Service Data Adaptation Protocol (SDAP), among which, for example: o The physical layer provides a transport channel to the media access control sublayer; o The MAC sublayer provides logical channels to the RLC sublayer; o The RLC sublayer provides RLC channels to the PDCP sublayer; o The PDCP sublayer provides radio bearers to the SDAP sublayer; o The SDAP sublayer provides 5GCQoS traffic; o Comp. is called header compression, and Segm. is called segmentation; o The control channels include (BCCH, PCCH).

[0094] Layer 3 (L3) includes, for example, Radio Resource Control (RRC), as per Section 6 of 3GPP TS 38.300 V16.6.0 (2021-06), which is covered by reference.

[0095] A radio access network (RAN) node or network node, such as a gNB, base station, gNB CU or gNB DU or a portion thereof, may be implemented using means, for example, having at least one processor and / or at least one memory (with computer-readable instructions (computer program)), wherein the at least one processor and / or at least one memory is configured to support and / or provide and / or process functions and / or features associated with the CU and / or DU, and / or at least one protocol (sub) layer of the RAN (radio access network), such as layer 2 and / or layer 3.

[0096] The gNB CU and gNB DU portions may, for example, be located in the same location or physically separated. The gNB CU may include two portions: a CU-CP and a CU-UP portion. The CU-CP portion may even be split into, for example, a first CP portion located at the CU and a second CP portion located at the DU. The first and second CP portions may perform different RRC operations and processes, such as central and local operations, or overlapping operations that may require coordination. The gNB DU may even be further split into, for example, two portions, one including processing equipment and the other including an antenna. The Central Unit (CU) may also be referred to as BBU / REC / RCC / C-RAN / V-RAN, O-RAN, or a portion thereof. The Distributed Unit (DU) may also be referred to as RRH / RRU / RE / RU, or a portion thereof. In the various exemplary embodiments of this disclosure below, the CU-CP (or more generally, the CU) may also be referred to as a (first) network node supporting at least one of the Central Unit Control Plane functions or Layer 3 protocols of the Radio Access Network; similarly, the DU may be referred to as a (second) network node supporting at least one of the Distributed Unit functions or Layer 2 protocols of the Radio Access Network.

[0097] gNB-DU supports one or more cells and can therefore be used as a serving cell for, for example, a user equipment (UE).

[0098] User equipment (UE) may include wireless or mobile devices, devices with a wireless interface for interacting with a RAN (Radio Access Network), smartphones, vehicle-mounted devices, wireless devices, M2M devices, etc. Such a UE or device may include: at least one processor; and at least one memory including computer program code; wherein the at least one memory and the computer program code are configured, together with the at least one processor, to cause the device to perform at least some operations, such as, for example, an RRC connection to the RAN. The UE is configured, for example, to generate messages (e.g., including a cell ID) to be transmitted to the RAN via radio (e.g., to reach and communicate with the serving cell). The UE may generate, transmit, and receive RRC messages including one or more RRCPDUs (Packet Data Units).

[0099] The UE may have different states (e.g., covered by reference to 3GPP TS 38.331 V16.5.0 (2021-06) Parts 42.1 and 4.4).

[0100] When an RRC connection has been established, the UE is either in an RRC_connected state or an RRC_inactive state.

[0101] In RRC_connection state, the UE can: o Store the AS context; o Transmit unicast data to / from the UE; o Monitor the control channel associated with the shared data channel to determine whether data is scheduled for the data channel; o Provides channel quality and feedback information; o Perform neighboring cell measurements and measurement reports.

[0102] The RRC protocol includes, for example, the following main functions: o RRC connection control; o Measurement configuration and reporting; o Establishing / modifying / releasing measurement configurations (e.g., intra-frequency, inter-frequency, and inter-RAT measurements); o Setting and releasing the measurement gap; o Measurement report.

[0103] Figure 2A An example of a RAN-based notification area (RNA) 200 is shown. A UE in an RRC_inactive state can be configured with a last-serving NG-RAN node having RNA 200. Typically, the RAN can cover a single cell or multiple cells. Figure 2A In the example shown, RNA 200 covers a subset of cells 1, 2, and 3. When the UE reselects a cell that is not part of the configured RNA, the UE periodically sends a RAN-based Notification Area Update (RNAU) as configured. Cells 1, 2, and 3 can be controlled by a network node, namely Central Unit (CU) 202, which supports the Central Unit Control Plane (CU-CP) function of the radio access network. Cell 1 can belong to the first distributed unit, cell 2 can belong to the second distributed unit, and cell 3 can belong to the third distributed unit. User Plane Function (UPF) 204 can be connected to Central Unit 112.

[0104] Figure 2B Another example of RNA 206 is shown. RNA 206 covers a subset of cells 1, 2, 3, 4, and 5. When the UE reselects a cell that is not part of the configured RNA, the configured UE periodically sends a RAN-based Notification Area Update (RNAU). Cells 1, 2, and 3 can be controlled by CU 208, and cells 4 and 5 can be controlled by CU 210. Cell 1 can belong to the first distributed unit, cell 2 to the second distributed unit, cell 3 to the third distributed unit, cell 4 to the fourth distributed unit, and cell 5 to the fifth distributed unit. CU 208 controls the first, second, and third distributed units, and CU 210 controls the fourth and fifth distributed units. UPF 204 can be connected to central units 208 and 210.

[0105] When considering setting the RNA to a relatively large region to reduce frequent RNAUs by the UE and to reduce paging costs, several paging strategies exist, such as: 1) Page the last known cell and hope the UE is there. It's very likely the UE has already left the cell. In this case, page only the last known cell will be ineffective because the UE cannot be detected on the first attempt. The network can then begin pageing (sequentially) potential cells where the UE might be located, which increases paging costs and connection re-establishment latency. 2) Simultaneously page the last known cell and neighboring cells, hoping the UE is there. The network layout (Error! Reference source not found.) can be quite complex. The UE might be located in a small coverage area of ​​a cell, not actually in the cell's main coverage area. If the last known cell has a large group of neighboring cells, this results in extensive paging of multiple neighboring cells. Furthermore, if the UE is not detected in either the last known cell or any neighboring cells, the network might begin (sequentially) paging potential cells where the UE might be located (outside of the last known and neighboring cells). This increases paging costs and the latency of locating the UE. 3) Simultaneously page all cells in the RNA. Since the UE performs RNAU when changing the RNA, it is known that the UE is in one cell of a given RNA. Ultimately, paging all cells in the RNA simultaneously and immediately locates the UE, but this results in significant network overhead.

[0106] Therefore, a solution is needed that does not cause significant network overhead while avoiding latency when locating the UE.

[0107] Figure 3 An example of a device 300 configured to practice one or more exemplary embodiments is shown. Device 300 may include a user node, user equipment, access node, access point, base station, wireless network node, or a subset thereof, or a device generally configured to implement the functions described herein. Device 300 may include at least one processor 302. The at least one processor 302 may include, for example, one or more of a variety of processing devices, such as a coprocessor, microprocessor, controller, digital signal processor (DSP), processing circuitry system with or without an accompanying DSP, or various other processing devices including integrated circuits, such as application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), microcontroller units (MCUs), hardware accelerators, dedicated computer chips, etc.

[0108] The device 300 may also include at least one memory 304. Memory 304 may be configured to store, for example, computer program code, such as operating system software and application software. Memory 304 may include one or more volatile memory devices, one or more non-volatile memory devices, and / or combinations thereof. For example, the memory may be implemented as a magnetic storage device (such as a hard disk drive, magnetic tape, etc.), an optical magnetic storage device, or a semiconductor memory (such as a mask ROM, PROM (programmable ROM), EPROM (erasable PROM), flash ROM, RAM (random access memory), etc.). Memory 304 is provided as an example of a (non-transient) computer-readable medium. The term "non-transient" as used herein refers to a limitation on the medium itself (i.e., tangible, not signaling), rather than a limitation on the persistence of data storage (e.g., RAM versus ROM).

[0109] Device 300 may also include a communication interface 308 configured to enable device 300 to send and / or receive information. Communication interface 308 may include internal or external communication interfaces, such as E1, F1, F1-C, and / or F2-C interfaces. Device 300 may also include other components and / or functions, such as a user interface (not shown) including at least one input device and / or at least one output device. Input devices may take various forms, such as a keyboard, touchscreen, or one or more embedded control buttons. Output devices may include, for example, a display, a speaker, etc.

[0110] When device 300 is configured to perform certain functions, some and / or more components of device 300, such as at least one processor 302 and / or at least one memory 304, can be configured to perform those functions. Furthermore, when at least one processor 302 is configured to perform certain functions, those functions can be implemented using, for example, program code 306 included in at least one memory 304.

[0111] The functions described herein can be performed, at least in part, by one or more computer program product components, such as software components. According to an example embodiment, device 300 includes a processor or processor circuitry, such as, for example, a microcontroller, configured by program code 306, which, when executed, performs embodiments of the operations and functions described herein. Program code 306 is provided as an example of instructions that, when executed by at least one processor 302, result in the performance of device 300.

[0112] Alternatively, or additionally, the functionality described herein may be performed at least in part by one or more hardware logic components. For example, but not limited to, illustrative types of hardware logic components that may be used include field-programmable gate arrays (FPGAs), application-specific integrated circuits (ASICs), application-specific standard products (ASSPs), system-on-a-chip (SoCs), complex programmable logic devices (CPLDs), graphics processing units (GPUs), and the like.

[0113] Device 300 may be configured to perform the methods(s) described herein or include components for performing the methods(s) described herein. In one example, the components include at least one processor 302, and the at least one memory 304 includes program code 306 configured to cause device 300 to perform the method when executed by at least one processor 302.

[0114] Device 300 may include, for example, user nodes, user equipment, or network devices, such as access nodes, access points, base stations, or their central / distributed units. Although device 300 is shown as a single device, it should be understood that the functionality of device 300 may be distributed across multiple devices, where applicable.

[0115] Figure 4 Explain the concept of Layer 1 / Layer 2 triggered Mobility Transaction (LTM) in a radio access network. Typically, LTM is the process by which the gNB receives measurement reports from the UE, and based on these reports, the gNB changes the UE's serving cell(s) via MAC CE. Figure 4 The example shown assumes that the decomposed architecture includes UE 400, source DU 402, target DU 404, and CU 406.

[0116] Steps 408 to 412: The UE sends an L3 measurement report message to the CU 406 via the source DU 402. The CU 406 decides to use LTM and initiates LTM candidate cell preparation.

[0117] Steps 414 to 416: CU 406 sends a UE context establishment request to target DU 404 to prepare the target cell.

[0118] Steps 418 to 420: CU 406 sends a UE context modification request to source DU 402 to prepare the target cell in source DU 402. Additionally, this message can be used to provide target cell information in source DU 402.

[0119] Steps 422 to 430: CU 406 prepares the RRC configuration and provides it to UE 400. UE 400 stores the configuration of the LTM candidate target cells and sends an RRCReconfigurationComplete message to CU 402.

[0120] Steps 432 to 434: UE 400 can perform DL synchronization and TA acquisition with the candidate target cell before receiving the LTM cell handover command.

[0121] Steps 436 to 440: UE 400 performs Layer 1 (L1) measurements on the configured LTM candidate target cells and sends a lower layer measurement report to source DU 402.

[0122] Steps 442-444: Source DU 402 decides to perform an LTM cell handover to the target cell and sends a MAC CE to trigger the LTM cell handover.

[0123] Step 446: The UE switches to the LTM candidate target cell configuration and accesses the target cell. If necessary (if the scheduled access is unavailable in advance), a random access procedure is performed.

[0124] Steps 448 to 450: UE 400 uses the RRC reconfiguration complete message to indicate to the target cell that the LTM cell handover has been successfully completed.

[0125] Steps 452 to 454: If CU 406 determines accordingly, the UE context is released.

[0126] Figure 5A A signaling diagram according to an example embodiment is shown. This example involves the following elements: UE 500, distributed unit DU1 502 of source gNB 508, distributed unit DU2 504 of source gNB 508, central unit CU1 506 of source gNB 508, distributed unit DU3 510 of target gNB 516, distributed unit DU4 512 of target gNB 516, and central unit CU2 514 of target gNB 516.

[0127] At 518, UE 500 is configured and operates with Layer 1 / Layer-triggered Mobility Detection (LTM). During the LTM preparation phase, target cells from the target DU are prepared, namely from DU2 504 and DU3 510.

[0128] At locations 520, 522, and 524, UE 500 sends Layer 1 (L1) measurement reports to DU 1 502. The measurements include measurements of the ready cells belonging to DU1 502, DU2 504, and DU3 510.

[0129] In 526, based on the UE request / transmission state (e.g., no DL / UL transmission), CU1 506 can decide to send an RRC release message (to trigger a suspension using suspendConfigIE) to trigger UE 500 to switch to an RRC inactive state (for clarity, in Figure 5A The message is marked as RRC pending. This message is sent to DU1 502 using DL RRC message delivery. In this message, CU1 506 can also indicate to DU1 502 that it needs the latest L1 measurement report (for a specific cell group). CU1 can also indicate that an L1 measurement report is needed for a specific time window.

[0130] In an example embodiment, CU1 506 may request L1 measurement after deciding to page the UE accordingly (i.e., at 538). In this case, based on the UE's inactivity time, CU1 506 may decide whether to request L1 measurement (i.e., determine the paging cell based on the L1 measurement) and also determine the request configuration (e.g., time window, number of cells requested, and threshold).

[0131] In another example embodiment, CU1 506 can request the ID / TCI status (or measurement) of the cell, which has been measured above a certain threshold within the last x seconds or N measurement instances.

[0132] At 528, DU1 502 sends an RRC hangup message to UE 500.

[0133] At 530, DU1 502 provides L1 measurements of UE 500 to CU1 506. L1 measurements involve a specific time window. The measurements may also indicate the Physical Cell ID (PCI) of the reported L1 measurements. DU1 502 can be configured to store L1 measurements received from UE 500. In the example embodiment, L1 measurements may be stored for a specific time or a configurable time.

[0134] At 532, CU1 506 can start a validity timer for L1 measurements. In an example embodiment, the validity timer can be coordinated with DU1 502. The validity timer ensures the validity of the measurements. If the timer expires, in one example embodiment, the L1 measurement can be considered obsolete and discarded. In another example embodiment, even if the validity timer has expired, some of the L1 measurements can still be used.

[0135] In 534 and 536, UE 500 switches to RRC inactivity and remains in RRC inactivity.

[0136] At or before 538, incoming traffic arrives at the last service CU, namely CU1 506. For example, based on traffic type requirements (e.g., if there are no low latency requirements), CU1 506 may consider the latest L1 measurement obtained at 530 to determine the paging strategy.

[0137] In an example embodiment, CU1 506 can determine the last serving cell to be paged and the cell indicated in a configurable number of last measurements (since L1 measurements are provided along with PCI).

[0138] In another example embodiment, CU1 506 can identify the mobility mode of UE 500 and page the corresponding cell. If the mobility mode is identified, this information can be used to determine the cell paging scheme.

[0139] In another example embodiment, CU1 506 can page the last serving cell and a subset of cells indicated in measurements within a specific time window.

[0140] In addition to any of the paging scheme examples mentioned above, for each identified cell, a beam set (e.g., in FR2) can be derived / selected based on L1 measurements to repeat the paging message.

[0141] Between 540 and 542, CU1 506 sends a paging message to UE 500 using the cell and beam indicated by the paging scheme (via the corresponding DUs, namely DU1 502 and DU3 510). In the example embodiment, the operation of the paging scheme can be monitored by a timer.

[0142] Figure 5B A signaling diagram according to another example embodiment is shown. It is possible for UE 500 to switch to a new cell belonging to a different CU (e.g., CU2514), and during cell handover, the target CU (i.e., CU2 514) can determine that UE 500 should change to an RRC inactive state. In this case, in order for CU2 504 to perform a valid paging, the source CU (i.e., CU1506) should provide L1 measurements to the target CU (i.e., CU2 514).

[0143] In 518, UE 500 is configured and operates in LTM mode, and the service DU is DU1 502.

[0144] At 546, UE 500 sends an L1 measurement report to DU1 502. The measurement includes cells belonging to DU1 502, DU2 504, and DU3 510.

[0145] At 548, LTM is used to switch UE 500 to DU3 510.

[0146] At 550, DU1 502 sends the latest L1 measurement report with a cell change trigger command to CU1 506. In the example embodiment, the measurement may involve a specific time window. DU1 502 can be configured to store L1 measurements received from UE 500. In the example embodiment, L1 measurements may be stored for a specific time or a configurable time.

[0147] At 552, CU2 514 notifies CU1 506 that the LTM switchover was successful.

[0148] At 554, CU1 506 provides CU2 514 with the latest L1 measurement report, which may be relevant to a specific time window. In another example embodiment, once CU2 514 determines in the transmission of the RRC release message that it needs these measurements (to trigger a suspension using suspendConfigIE), CU2 514 can request L1 measurements.

[0149] In 556, UE 500 uses the cell access network in DU3 510 with configured LTM.

[0150] The remaining steps 558-574 are the same as steps 528-542.

[0151] Figure 5C A signaling diagram according to another example embodiment is shown. Figure 5C In the example shown, UE 500 is already in an RRC inactive state and "wakes up" to notify the network about updates in the RNA.

[0152] Steps 518 and 577 to 584 correspond to the preceding information about Figure 5A Steps 518 to 534 are discussed.

[0153] At 585, the RNA update timer (T380) expires or the UE 500 removes the configured RNA.

[0154] In response to the trigger obtained at 585, at 586, UE 500 performs an RNA update for the new CU (i.e., CU2 514 via DU3 510) and provides the latest L3 measurement of the RNA update to CU2 514.

[0155] In 587 and 588, CU2 514 retrieves the UE context from the previously serving CU (i.e., CU1 506). CU1 506 also provides the latest L1 measurement to be used if CU2 516 needs to page UE 500 in the UE context retrieval response. CU1 506 may also provide the time of the L1 measurement measured by UE 500 to indicate the degree of obsolescence of the reported L1 measurement.

[0156] In 589, CU2 514 decided to put UE 500 into RRC inactive state again and reset the validity timer associated with L1 measurement.

[0157] Between 590 and 591, CU2 514 sends an RRC hangup message to UE 500 via DU3 510.

[0158] At 592, CU2 514 performs a path switch and notifies the AMF of the anchor cell change.

[0159] Figure 5D A signaling diagram according to another example embodiment is shown. Figure 5D In the example shown, UE 500 was already in an RRC inactive state and woke up to notify the network about updates in the RNA.

[0160] At 585, the RNA update timer (T380) expires or the UE 500 removes the configured RNA.

[0161] In response to the trigger obtained at 585, at 586, UE 500 performs an RNA update for the new CU (i.e., CU2 514 via DU3 510) and provides the latest L3 measurement of the RNA update to CU2 514.

[0162] In steps 593 and 594, UE 500 sends L1 measurement reports to DU3 510. The measurements include cells belonging to DU2 504 and DU3 510.

[0163] At positions 595 and 596, CU2 514 retrieves the UE context from the previously serving CU (i.e., CU1 506). CU1 506 also provides the latest L1 measurement to be used if CU2 516 needs to page UE 500 in the UE context retrieval response. CU1 506 may also provide the time of the L1 measurement measured by UE 500 to indicate the degree of obsolescence of the reported L1 measurement.

[0164] At 597, CU2 514 decided to put UE 500 into RRC inactive state again and reset the validity timer associated with L1 measurement.

[0165] Steps 598 to 600 and about Figure 5A The steps 526 to 530 discussed are the same.

[0166] In 601, CU2 514 performs a path switch and notifies the AMF about the anchor cell change.

[0167] Figure 6An example of a method for providing Layer 1 measurements when a user equipment is suspended at a network node supporting at least one of the Central Unit Control Plane (CU-CP) functions or Layer 3 protocols of a wireless access network is shown.

[0168] In 602, the method may include: establishing a connection to a user device by a network node.

[0169] In 604, the method may include: receiving information related to a Layer 1 measurement performed by a user equipment.

[0170] Figure 7 An example of a method for providing Layer 1 measurements when a user equipment is suspended at a network node supporting at least one of the distributed unit (DU) functions or Layer 2 protocols of a radio access network is shown.

[0171] In 700, the method may include: establishing a connection toward the user device.

[0172] In 702, the method may include: receiving a Layer 1 / Layer 2 triggered mobility (LTM) configuration message from a first network node supporting at least one of a Central Unit Control Plane (CU-CP) function or a Layer 3 protocol of a radio access network, the configuration message instructing a second network node to operate in the LTM and monitor Layer 1 measurements performed by and received from the user equipment.

[0173] In 704, the method may include: sending information related to the received Layer 1 measurement to the first network node.

[0174] Figure 8 An example of a method for providing Layer 1 measurements when a user equipment is suspended at a network node supporting at least one of the Central Unit Control Plane (CU-CP) functions or Layer 3 protocols of a wireless access network is shown.

[0175] In 800, the method may include: sending a Layer 1 measurement associated with a user equipment operating in a Layer 1 / Layer 2 triggered mobility (LTM) by a network node.

[0176] Figure 9 An example of a method for a user device to operate in an inactive state is shown.

[0177] At 900, the method may include: establishing a connection toward a first network node that supports at least one of the Central Unit Control Plane (CU-CP) functions or Layer 3 protocols of a wireless access network.

[0178] In 902, the method may include receiving a message from a first network node that includes instructions for operation in an inactive state.

[0179] In 904, the method may include: when operating in an inactive state, sending a Radio Resource Control (RRC) recovery request message that includes information related to at least one measurement performed by the user equipment.

[0180] Further embodiments will be described below. Some features of the embodiments may also be used in other embodiments and / or other features independent of the corresponding embodiments.

[0181] Starting with 3GPP TS 38.300 v17.3.0 (2022-12), the RRC inactivity state is described in

[0182] 7.2 Protocol Status

[0183] RRC support can characterize the following states: - RRC_Inactive: - PLMN selection; - Broadcasting system information; - Cell reselection mobility; - Initiate paging via NG-RAN (RAN paging); - RAN-based notification regions (RNAs) are managed by NG-RAN; - DRX configured by NG-RAN for RAN paging; - 5GC-NG-RAN connection (both C / U-plane) is used for UE establishment; - Store the UE's inactive AS context in both the NG-RAN and the UE; - NG-RAN knows which RNA the UE belongs to; - Transmit MBS broadcast data to the UE via (multiple) MRBs; - Transmit unicast data and / or signaling to / from the UE via the radio bearer configured for SDT.

[0184] Further measurements were performed while the device was inactive.

[0185] 7.3 System Information Processing

[0186] 7.3.1 Overview

[0187] System information (SI) includes MIB and multiple SIBs, which are divided into minimum SI and other SIs: - Other SIs encompass all SIBs not broadcast in the minimum SI. These SIBs can be broadcast periodically on the DL-SCH, or broadcast on demand on the DL-SCH (i.e., upon request from a UE in RRC_IDLE, RRC_Inactive, or RRC_Connected). Other SIs consist of the following: - SIB4 includes information about other NR frequencies and inter-frequency neighboring cells related to cell reselection (including frequency-common cell reselection parameters and cell-specific reselection parameters), which can also be used for NR idle / inactive measurements; - SIB11 contains information related to idle / inactive measurements.

[0188] 8.1 UE Identifier

[0189] The terms list the identifiers used by NR to connect to 5GC.

[0190] For NRs connected to 5GC, the following UE identifier is used at the NG-RAN level: - I-RNTI: Used to identify the UE context when RRC is inactive.

[0191] 9.2.2 RRC_Mobility in Inactive Activities

[0192] 9.2.2.1 Overview

[0193] RRC_Inactive is a state in which the UE remains connected to the CM and can move within the area configured by the NG-RAN (RNA) without notifying the NG-RAN. During RRC_Inactive, the last serving gNB node maintains the UE context and the NG connection associated with the UE and serving AMF and UPF.

[0194] If the UE is in RRC_inactive, and the last serving gNB receives DL data from the UPF or DLUE-related signaling from the AMF (other than the UE context release command message), it will page in the cell corresponding to the RNA, and if the RNA includes the cell of the neighboring gNB, it can send XnAP RAN paging to the neighboring gNB.

[0195] A UE in an RRC_inactive state needs to initiate an RNA update procedure when it moves outside its configured RNA. Upon receiving an RNA update request from the UE, the receiving gNB triggers an XnAP UE context retrieval procedure to obtain the UE context from the last serving gNB, and can decide whether to return the UE to the RRC_inactive state, move the UE to the RRC_connected state, or put the UE into RRC_IDLE. In the case of periodic RNA updates, if the last serving gNB decides not to relocate the UE context, this causes the UE context retrieval procedure to fail, and the UE is either returned to RRC_inactive or directly sent back to RRC_IDLE via an encapsulated RRC release message.

[0196] 9.2.2.3 RAN-based notification area

[0197] A UE in an RRC_inactive state can be configured by the last serving NG-RAN node with RNA, wherein: - The RNA may cover a single or multiple cells and should be included within the CN registration region; Xn linkages within the RNA should be available during the release; - RAN-based notification area updates (RNAU) are sent periodically by the UE, and are also sent when the UE selects a cell that does not belong to the configured RNA during the cell reselection process.

[0198] There are several different alternatives regarding how RNA should be configured: - List of residential communities: - Provide the UE with an explicit list of cells (one or more) that constitute the RNA. - RAN Area List: - Provide the UE with (at least one) RAN region ID, where the RAN region is a subset of or equal to the CN tracking region. A RAN region is specified by a RAN region ID, which consists of a TAC and optionally a RAN region code; - A cell broadcasts a RAN area ID in its system information, or broadcasts multiple RAN area IDs when the network shares broadcasts with multiple cell IDs.

[0199] NG-RAN can provide different RNA definitions to different UEs, but it cannot mix different definitions to the same UE at the same time. The UE should support all the RNA configuration options listed above.

[0200] 9.2.2.4 State Transition

[0201] 9.2.2.4.2 Network-triggered transition from RRC_inactive to RRC_connected

[0202] Figure 10 (Network-triggered transition from RRC_inactive to RRC_connected) describes the network-triggered transition from RRC_inactive to RRC_connected: 1. RAN paging trigger event occurs (input DL user plane, DL signaling from 5GC, etc.). 2. RAN paging is triggered; or it is configured to the UE in the RAN-based notification area (RNA) either only in the cell controlled by the last serving gNB, or also by Xn RAN paging in the cell controlled by other gNBs. 3. Use I-RNTI to page the UE. 4. If the UE has been successfully reached, attempt to resume from RRC_Inactive as described in Clause 9.2.2.4.1.

[0203] Therefore, the UE is first paged by the last serving gNB. If the UE is no longer accessible via the last serving gNB, for example due to mobility, different options for further paging may be possible, such as paging all cells of the RNA in parallel to reach the UE quickly, paging the UE with a cell of the RNA, and trying the next cell of the RNA if unsuccessful. This may take some time until the UE is reached, and may only be reached via a cell with certain access conditions (e.g., low signal strength), which may require a quick subsequent handover to a more suitable cell, which requires additional signaling, delays, etc. The goal is to improve access to the UE faster and better. Where the latest measurement results are stored in the last serving cell, such as those provided by a distributed unit, such as L3 and / or L1 measurements, for example, when LTM is configured, these measurements can also indicate the identified measurement cell and its signal strength. Thus, the priority for selecting the cell to send the paging signal can be defined, for example, first the last serving cell, then the cell with the highest signal strength, then the cell with the second highest signal strength, and so on. This increases the probability of quickly finding and accessing the UE. For example, due to UE movement, the UE may no longer be reachable via the last serving cell, but may still be in the neighborhood and therefore reachable with a high probability via one of the cells identified in the most recent measurements. Not only is fast access more likely, but access with good connectivity is also more likely. This reduces the risk of requiring rapid subsequent handover. The latest UE measurements can be provided to the last serving cell or another cell along with RNA updates. Alternatively, or additionally, the latest UE measurements can be provided to the last serving cell or another cell along with general recovery requests and / or SDT requests, for example, when a UE in RRC inactivity sends an RRC response request message along with UL SDT data and / or UL SDT signaling and / or the latest / available / actual measurement information. Measurement information may include: L1 measurement information, including, for example, the cell ID and associated signal strength measurements, or, for example, the PCI (or other cell ID) of the prepared cell, instead of L1 measurements.

[0204] The UE is configured and operates in LTM mode, for example. The CU decides to switch the UE to an inactive state and provides an RRC suspend message to each DU, informing the DU of the message's content and, for example, requesting L1 measurements within a specific time period. The DU provides the RRC suspend message to the UE and provides the corresponding L1 measurement to the CU, for example, providing the requested time period, or only once, for example, the latest L1 measurement received from the UE. The DU then releases the UE context and LTM configuration. The CU stores the received L1 measurements, or at least the cell ID or PCI.

[0205] When DL data arrives at the (anchor) CU, the latter identifies the appropriate cell to be paged (e.g., the last cell available in the L1 measurement report). The identified cells can be paged together at once, increasing the chances of discovering and connecting to the UE. Alternatively, priorities can be configured, for example, based on the last signal strength. That is, for example, the CU stores cells based on their strength, thus reducing storage requirements and configuring the access order.

[0206] The measurement information may optionally or additionally include: L3 measurement information including, for example, the cell ID and associated signal strength measurements, or, for example, the PCI (or other cell ID) of the measured cell, instead of complete L3 measurement information. The CU may store the measurement information (e.g., the cell ID prepared in the case of configuring LTM based on L3 and / or L1 measurement information received from the DU or another CU), and the UE may use this information for paging in the inactive state.

[0207] The CU can also use measurement information to generate the RNA. The RNA can be generated using the cell IDs of the (last) serving cell and its surrounding cells, for example, based on topology information, etc. However, these cells do not necessarily have to include the measurement cells. If the measured cells are added to the RNA, it will facilitate the selection of cells for paging and the order of selection, thus enabling faster and better UE access.

[0208] 9.2.2.5 RNA Update

[0209] Figure 11 (RNA Update Procedure with UE Context Relocation) describes a UE-triggered RNA update procedure involving context retrieval on Xn. This procedure can be triggered when the UE moves out of the configured RNA, or it can be triggered periodically. 1. Upon recovery from RRC_inactivity, the UE provides the I-RNTI assigned by the last serving gNB and an appropriate cause value, such as a RAN notification of an area update, and optionally with up-to-date measurement information, such as L1 measurements and / or cell ID, and / or PCI. This allows the gNB, such as the CU or CU-CP, to use this information to better page the UE in case it remains in inactive mode, and for example, later when DL data is introduced for the UE. 2. If the gNB can resolve the gNB identifier contained in the I-RNTI, the gNB requests the last serving gNB to provide the UE context, thereby providing the reason value received in step 1. 3. The last serving gNB can provide the UE context and optionally store UE measurement information (as assumed below). Alternatively, the last serving gNB can decide to move the UE to RRC_IDLE (and this process follows...). Figure 9 Steps 3 and subsequent steps of .2.2.5-3), or if the UE is still within the previously configured RNA, it is decided to keep the UE context in the last serving gNB and keep the UE in RRC_inactive (and this process follows Figure 9 (Steps 3 and subsequent steps of .2.2.5-2). This enables the gNB (e.g., CU or CU-CP) to use the information to better page the UE in case it remains in an inactive mode, and for example, later when DL data enters the UE. 4. The gNB can move the UE to an RRC connection (and the procedure follows...). Figure 9 Step 4 of .2.2.4.1-1, either return the UE to RRC_Idle (in which case the gNB sends an RRC release message), or return the UE to RRC_Inactive, as assumed below. 5. If it is necessary to prevent the loss of DL user data cached in the last service gNB, then the gNB provides a forwarding address. 6. / 7. gNB execution path switching. 8. The gNB keeps the UE in an RRC_inactive state by sending RRC release and suspend indications. 9. The gNB triggers the release of UE resources at the last serving gNB.

[0210] Figure 12 (Periodic RNA Update Procedure Without UE Context Relocation) describes the RNA update procedure when the UE is still within the configured RNA and the last serving gNB decides not to relocate the UE context and keeps the UE in RRC_inactive: 1. Upon recovery from RRC_inactivity, the UE provides the I-RNTI assigned by the last serving gNB and an appropriate cause value, such as a RAN notification of an area update, and optionally provides the latest measurement information, such as L1 measurements and / or cell ID and / or PCI. This allows the gNB (e.g., CU or CU-CP) to use this information to better page the UE in case it remains in inactive mode, and for example, later when DL data is introduced for the UE. 2. If the gNB is able to resolve the gNB identifier contained in the I-RNTI, the gNB requests the last serving gNB to provide the UE context, thereby providing the reason value received in step 1. 3. The last serving gNB stores the received information (e.g., C-RNTI and PCI associated with the cell to be restored) to be used in the next recovery attempt and responds to the gNB with a Retrieve UE Context Failure message including an encapsulated RRC release message. The RRC release message includes a pause indication. 4. The gNB forwards the RRC release message to the UE.

[0211] 9.2.4 Measurement

[0212] In an RRC connection, the UE measures multiple beams (at least one) of the cell and averages the measurements (power values) to derive cell quality. In doing so, the UE is configured to consider a subset of the detected beams. Filtering occurs at two distinct levels: beam quality is derived at the physical layer, and then cell quality is derived from multiple beams at the RRC layer. Cell quality from beam measurements is derived in the same manner for both serving and non-serving cells. If the gNB configures the UE to do this, the measurement report can include the measurement results of the X best beams.

[0213] The network can request the UE to measure NR and / or E-UTRA carriers via system information or via a dedicated measurement configuration during RRC_Idle or RRC_Inactive. If the UE is configured to perform NR and / or E-UTRA carrier measurements while in RRC_Idle or RRC_Inactive, it can provide an indication of the availability of the corresponding measurement results to the gNB in ​​an RRC setup completion message. The network can request the UE to report those measurements after security activation. The measurement request can be sent by the network immediately after sending the security mode command (i.e., before receiving security mode completion from the UE).

[0214] If the UE is configured to perform NR and / or E-UTRA carrier measurements while in RRC_inactive, the gNB can request the UE to provide the corresponding measurement results in the RRC recovery message, and the UE can then include the available measurement results in the RRC recovery completion message. Alternatively, the UE can provide the gNB with an indication of the availability of the measurement results in the RRC recovery completion message, and the gNB can subsequently request the UE to provide these measurement results.

[0215] Upon receiving an RRC suspend message to change the UE's state to inactive, the UE can be pre-configured or configured by the network to store available L1 and / or L3 measurements. Information related to the stored L1 and / or L3 measurements is included in the RRC recovery request message when providing RNA updates to the network and / or sending ULSDT data and / or UL SDT signaling. The UE can be pre-configured or configured by the network to perform L1 and / or L3 measurements in an inactive state. When the UE is configured with LTM, L1 measurements can be configured and / or applied, subsequently changing its state to inactive. Information related to the performed L1 and / or L3 measurements is included in the RRC recovery request message when providing RNA updates to the network and / or sending UL SDT data and / or UL SDT signaling.

[0216] The following shows a portion of 3GPP TS 38.300 v17.3.0 (2022-12) with modifications:

[0217] 8.18 Overall Procedure for Small Data Transfers During RRC Inactivity

[0218] 8.18.1 RACH-based SDT

[0219] Figure 13 The process of small data transfer based on RACH during RRC inactivity is shown (small data transfer based on RACH during RRC inactivity). 1. A UE in RRC inactivity sends an RRC recovery request message along with UL SDT data and / or UL SDT signaling, and / or optionally with the latest measurement information (e.g., L1 measurement and / or cell ID and / or PCI). This allows the gNB (e.g., CU or CU-CP) to use this information to better page the UE in case it remains in inactive mode, and for example, later when DL data enters the UE. 2. The gNB-DU buffers UL SDT data and / or UL SDT signaling, and / or optionally at least partially received measurement information. 3. Step 3, as defined in Step 4 of Clause 8.6.2, includes an instruction for SDT access. The gNB-DU may also provide SDT auxiliary information and / or optionally at least a portion of the received measurement information. 4-5. Steps 4-5 are as defined in steps 6-7 of Clause 8.9.6.2. If UL SDT data is available, it is forwarded to gNB-CU-UP, and if UL signaling is available, it is forwarded to gNB-CU-CP via UL RRC MESSAGE. In the UL RRC MESSAGE, any UL NAS PDU is delivered to the AMF.

[0220] 8.6 RRC State Transition

[0221] 8.6.1 RRC connected to inactive RRC

[0222] Assuming the gNB consists of gNB-CU and gNB-DU, this section provides the connection between the RRC and the inactive state transition of the RRC, such as... Figure 14 As shown (RRC connected to RRC inactive state transition process). 0. First, the gNB-CU determines that the UE has entered the RRC inactive mode from the connected mode. 1. The gNB-CU generates an RRC release message, which includes a suspend configuration for the UE. The RRC message is encapsulated in a UE context release command message to the gNB-DU. The UE context release command may also optionally include a request to the gNB-DU to provide the latest L1 measurement or related information received from the UE, for example, if the DU has previously been configured with LTM. The UE context release command may also include information that enables the DU to wait for or request the next L1 measurement from the UE before forwarding the RRC release to the UE, and enables the actual / very recent measurement to be sent to the CU. The UE context release command may also include information that enables the DU not to forward the RRC release to the UE if an L1-triggered cell change is expected. Cell changes and inactivity are concurrent processes. For example, an inactivity state may be used when there is no data input, allowing the UE to save power, for example, but it may be better for the UE to maintain a good connection. Therefore, if the cell change is planned / expected / anticipated, the cell change may receive higher priority and be executed. In this case, the DU will notify the CU that the cell change has been executed and will not change the inactivity state. The DU can, for example, provide the CU with the latest measurements to be forwarded to the UE to the new CU to which it is already connected. The new CU can then perform a change to an inactive state. When the new CU notifies the CU of a successful handover, the CU can also notify the new CU that the conditions for changing to an inactive state have been met. 2. gNB-DU forwards the RRC release message to the UE. 3. The gNB-DU responds with a UE context release complete message. The UE context release complete message may include the requested L1 measurement information.

[0223] The following shows a modified section of 3GPP TS 38.331 v17.3.0 (2022-12):

[0224] 4.2.1 Includes UE states and state transitions between RATs.

[0225] When an RRC connection has been established, the UE is in either the RRC_connected state or the RRC_inactive state.

[0226] - RRC_Inactive: - UE-specific DRX can be configured by the upper layer or the RRC layer; - At lower layers, the UE can be configured with DRX for PTM transmission of MBS broadcast; - UE-controlled mobility based on network configuration; - The UE stores the inactive AS context of the UE; - Configure a RAN-based notification area through the RRC layer; - Transmit unicast data and / or signaling to / from the UE on the radio bearer configured for SDT, and optionally transmit available measurement information, such as based on (pre)configuration.

[0227] - UE: - Monitor short messages sent via DCI in P-RNTI (see Clause 6.5); - During SDT, the control channel associated with the shared data channel is monitored to determine whether data is scheduled for it; - When the SDT process is not in progress, unless the UE is acting as an L2U2N remote UE, monitor the paging channel for CN paging using 5G-S-TMSI and RAN paging using full I-RNTI; - If the upper layer is configured for MBS multicast reception and the SDT process is not in progress, then TMGI is used to monitor the paging channel for paging. - Perform neighboring cell measurements and cell (re)selection; - For example, based on (pre)configuration, RAN-based notification area updates are performed periodically and when moving outside the configured RAN-based notification area, and optionally, available measurement information is transmitted along with them; - Request system information while the SDT process is not in progress, and can send an SI request (if configured); - When the SDT process is not in progress, perform the recording of available measurements and configure the UE's location and time for the recording of measurements; - Configure the UE to perform idle / inactive measurements when no SDT process is in progress; - If configured by the upper layer for MBS broadcast reception, collect MCCH change notifications and MBS broadcast control information and data; - Send SRS for location.

[0228] Other features of the method arise directly from the functionality of the (multiple) DU, (multiple) CU, or UE, as described throughout the specification, claims, and drawings, and therefore will not be repeated herein. The apparatus may be configured to perform or cause performance of any aspect of the method described herein. Furthermore, a computer program or computer program product may include instructions for causing the apparatus to perform any aspect of the method(s) described herein when executed by the apparatus. Additionally, an apparatus may include components for performing any aspect of the method described herein. According to an example embodiment, the components include at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus to perform at least any aspect of the method(s).

[0229] One or more of the examples and embodiments discussed above can implement solutions in which more efficient paging can be provided. This can be achieved, for example, due to the fact that it is not necessary to page the entire RNA in order to identify the UE. Furthermore, one or more of the examples and embodiments discussed above can implement solutions in which the most likely location of the UE can be paged.

[0230] Any ranges or device values ​​given herein may be extended or modified without losing the desired effect. Furthermore, any embodiment may be combined with another embodiment unless expressly prohibited.

[0231] Although the subject matter has been described using language specific to structural features and / or actions, it should be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or actions described above. Rather, the specific features and actions described above are disclosed as examples of implementing the claims, and other equivalent features and actions are intended to be within the scope of the claims.

[0232] It should be understood that the above benefits and advantages may relate to one embodiment or several embodiments. The embodiments are not limited to embodiments that solve any or all of the described problems or that have any or all of the described benefits and advantages. It will also be understood that references to "a" may refer to one or more of these items.

[0233] The steps or operations described herein can be performed in any suitable order, or simultaneously where appropriate. Furthermore, individual boxes can be removed from any method without departing from the scope of the subject matter described herein. Aspects of any of the example embodiments described above can be combined with aspects of any other example embodiments described to form further example embodiments without losing the desired effect.

[0234] The term "comprising" is used herein to mean including the identified method, block, or element, but such block or element does not include an exclusive list, and the method or apparatus may include additional blocks or elements.

[0235] As used herein, "at least one of the following" means "a list of two or more elements" and "at least one of the <list of two or more elements>" and similar wording, wherein a list of two or more elements connected by "and" or "or" means at least any one element, or at least any two or more elements, or at least all elements.

[0236] Although a topic may be referred to as 'first' or 'second' topic, this does not necessarily indicate any order or importance of the topics. Rather, such an attribute may be used solely for the purpose of distinguishing between topics.

[0237] As used in this application, the term "circuit system" may refer to one or more or all of the following: (a) a hardware circuit implementation only (e.g., an implementation in an analog and / or digital circuit system only) and (b) a combination of hardware circuitry and software, such as (if applicable): (i) a combination of analog and / or digital hardware circuitry with software / firmware, and (ii) any portion of a hardware processor with software (including digital signal processors), software, and memory, which work together to enable a device such as a mobile phone or server to perform various functions, and (c) hardware circuitry and / or processors, such as microprocessors or portions thereof, which require software (e.g., firmware) for operation, but may be absent when the software is not required for operation. This definition of circuit system applies to all uses of the term in this application, including in any claim.

[0238] As another example, as used herein, the term "circuit system" also encompasses implementations of hardware circuitry or processors (or processors in general) or portions thereof and their accompanying software and / or firmware. The term "circuit system" also encompasses (e.g., and if applicable to elements of a particular claim) baseband integrated circuits or processor integrated circuits for mobile devices or similar integrated circuits in servers, cellular network devices, or other computing or networking devices.

[0239] It should be understood that the above description is given by way of example only, and various modifications can be made by those skilled in the art. The foregoing description, examples, and data provide a complete description of the structure and use of exemplary embodiments. Although various embodiments have been described above with a degree of specificity or by reference to one or more individual embodiments, those skilled in the art can make various changes to the disclosed embodiments without departing from the scope of this specification.

Claims

1. A first network node supporting at least one of the Central Unit Control Plane (CU-CP) function or Layer 3 protocol of a radio access network, the first network node comprising: At least one processor; as well as At least one memory storing instructions that, when executed by the at least one processor, cause the first network node to at least: Establish a connection to the user device; and Receive information related to Layer 1 measurements performed by the user equipment.

2. The first network node according to claim 1, wherein the information related to the layer 1 measurement includes: The associated time window, and / or associated validity timer, and / or associated timing information indicating the validity of the provided measurement results.

3. The first network node according to claim 1 or 2, wherein the instructions, when executed by the at least one processor, cause the first network node to perform: Send a message that triggers the provision of information related to the measurement of layer 1.

4. The first network node according to any one of claims 1-3, wherein the instructions, when executed by the at least one processor, cause the first network node to perform: Start the validity timer for the measurement of layer 1.

5. The first network node according to any one of claims 1-4, wherein the layer 1 measurement comprises: Layer 1 measurements received from a source network node and a target network node, wherein the source network node supports at least one of the Central Unit Control Plane (CU-CP) function or Layer 3 protocol of the radio access network, and the target network node supports at least one of the Distributed Unit (DU) function or Layer 2 protocol of the radio access network.

6. The first network node of claim 1, wherein the instructions, when executed by the at least one processor, cause the first network node to perform: The Layer 1 measurement is received from a source network node using a retrieve UE context response message, the source network node supporting at least one of the Central Unit Control Plane (CU-CP) function or Layer 3 protocol of the radio access network.

7. The first network node of claim 6, wherein the instructions, when executed by the at least one processor, cause the first network node to perform: The RAN notification area update message is used to receive Layer 3 measurements associated with the user equipment.

8. The first network node according to any one of claims 1-7, wherein the instructions, when executed by the at least one processor, cause the first network node to perform: Receive incoming services for the user equipment; and The user equipment is paged according to the paging scheme associated with the Layer 1 measurement.

9. The first network node of claim 8, wherein the instructions, when executed by the at least one processor, cause the first network node to perform: The last serving cell of the user equipment being paged, and the cell indicated in the configurable number of last measurements.

10. The first network node of claim 8, wherein the instructions, when executed by the at least one processor, cause the first network node to perform: Identifying the mobility mode of the user equipment; and Paging the cell associated with the mobility pattern.

11. The first network node of claim 8, wherein the instructions, when executed by the at least one processor, cause the first network node to perform: Page the last serving cell of the user equipment and the subset of cells indicated in the Layer 1 measurement.

12. The first network node according to any one of claims 9-11, wherein the instructions, when executed by the at least one processor, cause the first network node to perform: Based on the Layer 1 measurements, a set of beams is selected for each identified cell.

13. The first network node according to claim 1 or 2, wherein the instructions, when executed by the at least one processor, cause the first network node to perform: The Layer 1 measurement is sent to a target network node that supports at least one of the Central Unit Control Plane (CU-CP) function or Layer 3 protocol of the radio access network.

14. A second network node supporting at least one of the Distributed Unit (DU) function or Layer 2 protocol of a radio access network, the second network node comprising: At least one processor; as well as At least one memory storing instructions that, when executed by the at least one processor, cause the second network node to at least: Establish a connection to the user device; The second network node receives a mobility LTM configuration message triggered by a layer 1 or layer 2 protocol from a first network node, the first network node supporting at least one of the central unit control plane (CU-CP) function or layer 3 protocol of the radio access network, the LTM configuration message instructing the second network node to operate in LTM mode and monitor layer 1 measurements performed by the user equipment and received from the user equipment. as well as Send information related to the received Layer 1 measurement to the first network node.

15. The second network node of claim 14, wherein the information related to the received Layer 1 measurement includes: The associated time window, and / or associated validity timer, and / or associated timing information indicating the validity of the provided measurement results.

16. The second network node according to claim 14 or 15, wherein the instructions, when executed by the at least one processor, cause the second network node to perform: A Radio Resource Control (RRC) release message is received from the first network node. The RRC release message is forwarded to the user equipment to instruct the user equipment to operate in an inactive state. Along with the RRC release message, a request for providing information related to the Layer 1 measurement is received.

17. The second network node according to claim 14 or 15, wherein the instructions, when executed by the at least one processor, cause the second network node to perform: Send an LTM cell change trigger message to the user equipment; and A message is sent to the first network node, the message indicating the triggered LTM cell change and including the information related to the Layer 1 measurement.

18. A first network node supporting at least one of the Central Unit Control Plane (CU-CP) function or Layer 3 protocol of a radio access network, the first network node comprising: At least one processor; as well as At least one memory storing instructions that, when executed by the at least one processor, cause the first network node to at least: Send Layer 1 measurements associated with the user equipment, which triggers a Layer 1 / Layer 2 mobility LTM operation.

19. The first network node of claim 18, wherein the instructions, when executed by the at least one processor, cause the first network node to perform: The Layer 1 measurement is sent to the target network node using a retrieve UE context response message, the target network node supporting at least one of the Central Unit Control Plane (CU-CP) function or Layer 3 protocol of the radio access network.

20. The first network node of claim 18, wherein the instructions, when executed by the at least one processor, cause the first network node to perform: In response to receiving a handover success message, the Layer 1 measurement is sent to the target network node, which supports at least one of the Central Unit Control Plane (CU-CP) function or Layer 3 protocol of the radio access network.

21. A user equipment for operating in an inactive state, the user equipment comprising: At least one processor; as well as At least one memory stores instructions that, when executed by the at least one processor, cause the user equipment to at least: Establish a connection toward a first network node, the first network node supporting at least one of the Central Unit Control Plane (CU-CP) function or Layer 3 protocol of the wireless access network; Receive a message from the first network node, the message including instructions to operate in the inactive state; and When operating in the inactive state, a Radio Resource Control (RRC) recovery request message is sent, the RRC recovery request message including information related to at least one measurement performed by the user equipment.

22. The user equipment of claim 21, wherein the information is related to layer 1 and / or layer 3 measurements performed by the user equipment.

23. A method performed by a first network node, the first network node supporting at least one of a Central Unit Control Plane (CU-CP) function or a Layer 3 protocol of a radio access network, the method comprising: Establish a connection to the user device; as well as Receive information related to Layer 1 measurements performed by the user equipment.

24. A method performed by a second network node, the second network node supporting at least one of a Distributed Unit (DU) function or a Layer 2 protocol of a radio access network, the method comprising: Establish a connection to the user device; The second network node receives a mobility LTM configuration message triggered by a layer 1 or layer 2 protocol from a first network node, the first network node supporting at least one of the central unit control plane (CU-CP) function or layer 3 protocol of the radio access network, the LTM configuration message instructing the second network node to operate in LTM mode and monitor layer 1 measurements performed by the user equipment and received from the user equipment. as well as Send information related to the received Layer 1 measurement to the first network node.

25. A method performed by a first network node, the first network node supporting at least one of a Central Unit Control Plane (CU-CP) function or a Layer 3 protocol of a radio access network, the method comprising: Send Layer 1 measurements associated with the user equipment, which triggers a Layer 1 / Layer 2 mobility LTM operation.

26. A method for operating a user equipment, the user equipment operating in an inactive state, the method comprising: Establish a connection toward a first network node, the first network node supporting at least one of the Central Unit Control Plane (CU-CP) function or Layer 3 protocol of the wireless access network; Receive a message from the first network node, the message including instructions to operate in the inactive state; and When operating in the inactive state, a Radio Resource Control (RRC) recovery request message is sent, the RRC recovery request message including information related to at least one measurement performed by the user equipment.

27. A computer program comprising instructions for causing a device to perform the method according to any one of claims 23-26.

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