Notification area management in wireless networks

Abstract

A method of operating a first base station (130) to configure a notification area (40), wherein the first base station (130) includes a first central unit (131) CU and one or more first distributed units (132) DUs controlled by the first CU, the method comprising: receiving (708) first information (73) identifying a notification area update from a second base station (140), the second base station including a second CU (141) and one or more second DUs (142, 143) controlled by the second CU, wherein the first information is based on a message (71) identifying a notification area update procedure obtained in one of the second DUs (142) from a user equipment UE (10) configured with a first notification area including the first base station; establishing (710, 712) a connection (50, 60) between the first CU and the one second DU; and configuring (714) the UE with second information (78), the second information identifying the addition of the one second DU to the first notification area.

Description

Technical Field

[0001] The present disclosure relates to methods and apparatus in a wireless communication system including a wireless network and a wireless terminal. Specifically, a solution is provided for managing a notification area of ​​a terminal that moves between cells of the wireless network while suspending or deactivating connection with a radio access network of the wireless network. Background Art

[0002] In various generations of radio communication systems, such as those provided by the 3rd Generation Partnership Project (3GPP), specifications of various generations have been provided to establish common rules for establishing and operating the radio interface between wireless terminals and base stations, as well as various operational levels of the network. In the 3GPP specifications, terminals are generally referred to as user equipment (UE), and for simplicity, this term will be used consistently herein. Base stations and various terms (also referred to as access nodes) that are operable to provide radio access to UEs within a cell are used in 3GPP for different types of systems or specifications. In the so-called 3G specifications, also known as Universal Mobile Telecommunications System (UMTS), the term nodeB is used to represent the base station, while in the so-called 4G specifications, also known as Long Term Evolution (LTE), the term eNodeB (eNB) is used. A further developed set of specifications for radio communications is referred to as a 5G-type radio communication system (5GS), including New Radio (NR) technology, in which the term gNodeB (gNB) is used to represent the base station.

[0003] For many types of radio communication systems, different states may be defined in which the operations of the parties may take different forms. Typically, at least two different states may be defined in most types of radio communication systems, such as RRC connected and RRC idle in the RAN domain.

[0004] In the idle state, the UE will remain in an idle mode in which the UE is not currently sending or receiving data. In this state, the UE may, for example, periodically monitor signals sent from a base station to maintain minimal contact with the network through the base station of the cell in which the UE is camped, for example, to maintain synchronization, monitor system information, and be ready to receive paging messages if there is a downlink traffic flow addressed to the UE.

[0005] In the connected state or active state, one or more radio resources have been provided to the UE, forming an active dedicated connection through the base station for receiving or sending data. The UE is then in connected mode.

[0006] Therefore, transitioning from the idle state to the connected state involves an access procedure to establish an active radio link for data communication. Such an access procedure is typically initiated on the random access channel (RACH) and will not be described in detail herein. However, when the UE initiates entry into the connected state, this may involve signaling and messaging with another cell and base station that is not the last base station with which the UE established a connection in the connected state. However, efforts have been made in 4G and 5G to reduce overall system signaling. In 4G, this feature is called user plane EPS CIoT (Evolved Packet System - Cellular Internet of Things) optimization, while in 5G, there are two features: CMCONNECTED with RRC_Inactive state, and user plane 5GS CIoT optimization. Both solutions are based on storing information related to the UE's connection in the access node (also known as the anchor node) to which the UE last connected, and reusing this information using the suspend / release and resume functions. UE-specific information is also known as UE context. When a UE is powered on, it has no state and requires an initial attach to register with the core network. After registration, the UE will reside in idle mode. Thereafter, in the case of initiating downlink or uplink traffic flow, the UE can move to RRC connection using the connection establishment process. If there is no activity from the UE for a period of time, the RAN can suspend the UE and its radio connection by moving the UE to RRC_Inactive or RRC Idle (user plane 5G SCIoT optimization). Note that when the RRC inactive feature is used, the core network PDU session and N3 tunnel remain active, i.e. the PDU session and N3 tunnel are not suspended, and when the UE resumes the radio connection to transfer data, no signaling between the CN and RAN is required. The UE can then resume its radio connection to move to RRC connected mode.

[0007] When the RRC inactive feature is used, the wireless network may be configured with a notification area comprising a plurality of cells, each served by one or more base stations. The notification area identifies the cell in which the RAN will perform paging if the network is configured to connect to the UE. In the event that the UE moves between different notification areas, this will result in re-anchoring of the UE, where the UE context is moved to another base station configured with another notification area, i.e. a new anchor node. In a system where the UE context or connection data is stored or maintained in the previously used base station, the UE may later initiate a network connection through another base station based on a paging message associated with a downlink traffic flow, or initiate a RACH procedure based on an uplink traffic flow. Setting up a connection may involve a significant amount of processing and signaling, at least within the radio access network, before any data packets can be routed to the core network of the wireless network. Signaling may involve transferring context and switching the tunnel between the base station and the core network from the previous base station to the new base station. Summary of the Invention

[0008] A general object is to provide a solution for data routing in a wireless network including a radio access network, in particular in situations where a UE, whose network connection has been suspended, attempts to connect via one base station to send data, and information related to the previous connection is stored in another base station. In particular, the object is to provide such a solution in situations where one or more base stations of the radio access network include a central unit and one or more distributed units controlled by the central unit.

[0009] According to a first aspect, the solution relates to a method of operating a first base station to configure a notification area, wherein the first base station comprises a first central unit CU and one or more first distributed units DU controlled by the first CU, the method comprising the following steps:

[0010] receiving first information identifying a notification area update from a second base station, the second base station including a second CU and one or more second DUs controlled by the second CU,

[0011] wherein the first information is based on a message notifying an area update procedure of an identifier obtained in one of the second DUs from a UE configured with a first notification area including the first base station;

[0012] establishing a connection between the first CU and the one second DU; and

[0013] The UE is configured with second information, where the second information identifies adding the second DU to the first notification area.

[0014] According to a second aspect, the solution relates to a method for operating a user equipment UE to configure a notification area in a radio access network, the method comprising the following steps:

[0015] receiving information identifying a first notification area including a first base station, the first base station including a first central unit CU and one or more first distributed units DU controlled by the first CU;

[0016] receiving a signal from a second base station identifying a second DU that does not form part of the first notification area;

[0017] sending a first message to the second base station;

[0018] A second message including updated notification area information is received from the second DU, the updated notification area information identifying that the second DU is added to the first notification area.

[0019] The proposed solution mitigates inappropriate signaling in the wireless network by providing updated configuration of a UE-specific notification area instead of performing a re-anchoring procedure that would involve transferring UE context between the old RAN anchor node and the new anchor node, releasing and re-establishing a tunnel between the core network and the RAN anchor node configured for the new notification area. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Various embodiments will be described with reference to the accompanying drawings, in which

[0021] Figure 1 Schematically illustrated is a wireless network comprising a radio access network comprising at least two base stations, wherein each base station comprises a central unit and at least one distributed unit.

[0022] Figure 2 Elements included in a UE configured according to an embodiment are schematically shown.

[0023] Figure 3A and Figure 3B The functional elements included in a base station configured according to various embodiments are schematically shown.

[0024] Figure 4 The movement of the UE between two different notification areas is shown.

[0025] Figure 5 schematically illustrates the establishment of a connection between entities of two base stations covering different notification areas, and the formation of an updated notification area according to various embodiments;

[0026] Figure 6schematically illustrates the establishment of a connection between entities of two base stations covering different notification areas, and the formation of an updated notification area according to various embodiments;

[0027] Figure 7A Schematically shows the Figure 5 Signaling diagram of an implementation method of operation in a scenario.

[0028] Figure 7B Schematically shows the Figure 6 Signaling diagram of an implementation method of operation in a scenario. DETAILED DESCRIPTION

[0029] The present invention will be described more fully hereinafter with reference to the accompanying drawings, in which embodiments of the invention are shown. However, the invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

[0030] It should be understood that when an element is referred to as being "connected" to another element, it can be directly connected to the other element, or there can be an intermediate element. On the contrary, when an element is referred to as being "directly connected" to another element, there is no intermediate element. The same reference numerals always represent the same element. It should also be understood that although the terms first, second, etc. can be used here to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element can be referred to as a second element, and similarly, a second element can be referred to as a first element, without departing from the scope of the present invention. As used herein, the term "and / or" includes any and all combinations of one or more associated listed items.

[0031] For the sake of brevity and / or clarity, well-known functions or configurations may not be described in detail. Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention belongs. It should also be understood that terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of this specification and the related art, and should not be interpreted as idealized or overly formal meanings that are explicitly defined as such here.

[0032] Embodiments of the present invention are described herein with reference to schematic diagrams of idealized embodiments of the invention. Therefore, variations in the shapes and relative sizes of the illustrations, for example, due to manufacturing techniques and / or tolerances, are to be expected. Therefore, embodiments of the present invention should not be construed as limited to the specific shapes and relative sizes of the regions shown herein, but rather include deviations in shapes and / or relative sizes, for example, due to different operational constraints and / or due to manufacturing constraints. Therefore, the elements shown in the drawings are schematic in nature, and their shapes are not intended to illustrate the actual shape of a region of the device and are not intended to limit the scope of the invention.

[0033] It may be noted that where this disclosure refers to sending or receiving information, that information may be conveyed in one or more messages.

[0034] This document outlines various implementations generally applicable to 3GPP wireless communication networks. For this purpose, the term UE is often used to refer to a UE, while NB, eNB, or gNB are terms used to refer to a wireless access node or base station. A radio access network (RAN) may include multiple base stations that may be connected to a core network (CN).

[0035] In LTE, a UE can be in idle or connected mode relative to the network. An idle UE has no dedicated signaling or data bearers associated with it. In other words, no network / radio resources are specifically allocated to the UE. The location of an idle UE is known to the network only within a group of neighboring cells called a tracking area. Although an idle UE is not connected to any base station, it is required to select a suitable cell and camp on that cell. The process by which an idle UE selects and camps on a cell is called cell selection. While camping on a cell, an idle UE continues to regularly monitor the signal quality of the cell it is camping on. In the event that a quality level limit is reached (e.g., the signal quality is below a threshold), the UE may monitor other cells and may decide to do so if the radio conditions indicate that camping on another cell may be beneficial, for example due to UE mobility. This process is called cell reselection. The limits used by an idle UE for selecting / reselecting a cell are regularly communicated to the UE by each cell via system information broadcast messages.

[0036] In 5G networks, a new working state is defined, called the inactive state or RRC_Inactive. In this state, the UE is still in the CM_Connected state in the CN, which means that there is a pending active session to the CN, which is associated with the UE. More specifically, this may involve maintaining active interfaces between the RAN and the CN, including N2 (signaling interface between the RAN and the CN) and N3 (user data interface between the RAN and the CN). These interfaces remain active within the base station that executed the last service flow (typically the last base station to which the UE was connected in the RRC_Connected state). From the RAN perspective, the UE is in the RRC_Inactive state, where the UE context is stored in the RAN, which means that the UE will perform tasks similar to when the UE is in idle mode.

[0037] From the UE's perspective, one difference between RRC_Inactive and RRC_Idle is the area in which the UE needs to monitor, or the area in which the UE can reselect a cell without notifying the network. In states RRC_IDLE and CM_Idle, the UE is in idle mode and the UE monitors a Registration Area (RA), which can be a TA or a TA list. If the UE moves out of this area, the UE needs to perform a mobility registration. In state RRC_Inactive, where the UE also needs to monitor cell performance and, if necessary, reselect a cell to camp on in an area, this area is configured by the RAN and is called a RAN Notification Area (RNA). If the UE moves out of the RNA, the UE needs to perform an RNA update due to mobility.

[0038] RNA can be composed of multiple cells connected to the cell or base station to which the UE was last connected, or multiple cells having interfaces to the cell or base station to which the UE was last connected, and the multiple cells are also called anchor cells. The RAN anchor cell is a RAN node with N2 and N3 interfaces (control plane and user plane) to the CN. These interfaces are similar to the S1-C and S1-U interfaces of LTE. The base stations of other cells of RNA are connected to the anchor cell base station through a logical node-to-node interface. In 5G, this interface or set of interfaces is called the Xn interface and has a purpose similar to the X2 interface defined for LTE. The Xn interface is used between two gNBs connected to the CN and supports multiple functions. This includes control plane functions such as interface management and error handling, connection mode mobility management, UE context forwarding, RAN paging support, etc., as well as user plane functions such as data forwarding and flow control.

[0039] Figure 1A wireless network 100 is shown according to various embodiments. The wireless network 100 may be a radio communication network, such as a New Radio (NR) network, operating under general and specific regulations and restrictions promulgated by 3GPP. The wireless network 100 may include a core network 110 that is connected to other networks, such as the Internet. The wireless network 100 also includes an access network 120 that includes a plurality of base stations or access nodes, of which a first base station 130 and a second base station 140 are shown.

[0040] Also shown is a UE 10, which may access the wireless network through any base station included in the RAN 120. The UE 10 may be any device operable to wirelessly communicate with the network 100 through the base stations 130, 140, such as a mobile phone, computer, tablet, M2M device, IoT device, or other device.

[0041] When UE 10 is in RRC_Inactive, the radio connection between UE 10 and network 100, and in particular access network 120, is suspended, while an active session with CN 110 is maintained for UE 10. In this case, RAN 120 needs to define an appropriate notification area or RAN paging area. This can be statically defined, for example, including the last used cell and possibly a first, second, or third ring of cells surrounding the last used cell. Alternatively, the notification area can be assigned more dynamically, for example based on neighboring cell measurements that UE 10 has made and reported to the serving base station in connected mode. The notification area, such as an RNA, is defined by a cell list. As specified in 3GPP Technical Specification 38.300, the state RRC_inactive means that UE 10 remains in CM-CONNECTED and can move within the area configured by the RNA without notifying the anchor RAN node / cell. In RRC_inactive, the last serving base station maintains the UE context and the N2 connection to the serving AMF (Access and Mobility Management Function) and the N3 connection to the UPF (User Plane Function) associated with the UE. For simplicity, these two connections are Figure 1 If, when the UE is in RRC_inactive, the last serving base station receives downlink (DL) data from the UPF or downlink UE-associated signaling from the AMF (except the UE Context Release Command message), the last serving base station pages in the cell corresponding to the RNA and can send so-called XnAP RAN paging to neighboring base stations.

[0042] exist Figure 1In the RAN 120 of the present invention, at least two base stations 130 and 140 are configured with an architecture in which the base station functions are divided into two different types of entities. The first base station 130 includes a first entity as a central unit (CU) 131 and a second entity as one or more distributed units (DU) 132, 133. Accordingly, the second base station 140 includes a CU 141 and one or more DUs 142, 143. This architecture type is described in particular in Section 6 of the 3GPP technical specification TS38.401 version number 15.6.0 release number 15. The CU is responsible for RRC / SDCP / PDCP, and the DU is responsible for RLC / MAC / PHY. The CU and the DU are connected via a logical interface F1, which can transmit control signaling V1-C or data packets V1-U. Each DU serves one cell and has an associated cell ID. The actual transmission and reception points of the respective DUs 132, 133, 142, 143 may be referred to as transmission and reception points (TRPs), which may be considered as network nodes that include or are co-located with the antenna systems of the respective DUs.

[0043] In the first base station 130, one CU 131 is thus connected to multiple DUs 132 and 133, and together they cover the first notification area or a portion thereof, as discussed above in the RNA. Correspondingly, in the second base station 140, one CU 141 is thus connected to multiple DUs 142 and 143, and together they can cover the second notification area or a portion thereof.

[0044] Figure 2 Schematically illustrated is an embodiment of a UE 10 for use in a wireless network 100 as presented herein and for performing the outlined method steps.

[0045] The UE 10 may include a radio unit 213 comprising a radio transceiver for communicating in different frequency bands with other entities of the radio communication network 100, such as base stations 130, 140. Thus, the radio unit 213 may include a radio receiver and a transmitter for communicating over at least one air interface.

[0046] The UE 10 further comprises logic 210 configured to transmit data to the wireless communication network 100 over a radio channel via the radio unit, and possibly directly with another terminal through device-to-device (D2D) communication.

[0047] The logic 210 may include a processing device 211, which includes one or more processors, microprocessors, data processors, coprocessors, and / or some other type of component that interprets and / or executes instructions and / or data. The processing device 211 may be implemented as hardware (e.g., a microprocessor, etc.) or a combination of hardware and software (e.g., a system on a chip (SoC), an application-specific integrated circuit (ASIC), etc.). The processing device 211 may be configured to perform one or more operations based on an operating system and / or various applications or programs.

[0048] Logic 210 may also include memory 212, which may include one or more memories and / or one or more other types of storage media. For example, memory 212 may include random access memory (RAM), dynamic random access memory (DRAM), cache, read-only memory (ROM), programmable read-only memory (PROM), flash memory, and / or some other type of memory. Memory 212 may include a hard disk (e.g., a magnetic disk, an optical disk, a magneto-optical disk, a solid-state disk, etc.).

[0049] The memory 212 is configured to store computer program code that can be executed by the processing device 211, wherein the logic 210 is configured to control the UE 10 to perform any method steps provided herein. The software defined by the computer program code may include applications or programs that provide functions and / or processes. The software may include device firmware, an operating system (OS), or various applications that can be executed in the logic 210.

[0050] The UE 10 may also include or be connected to an antenna 214, which may include an antenna array.

[0051] Obviously, the UE 10 may include other features and elements in addition to those shown in the figures or described herein, such as a power supply, a housing, a user interface, one or more sensors, etc.

[0052] In various embodiments, the UE 10 is configured to perform the method steps outlined herein for execution in the UE.

[0053] Figure 3A and Figure 3B Schematically shown is a base station 130 for use in the radio communication network 100 presented herein and for performing the method steps as outlined herein. It should be noted that Figure 3A and Figure 3B The implementation manner can also be applied to the second base station 140.

[0054] Base station according to reference Figure 1 The architecture shown and described is configured to include a CU 131 and one or more DUs 132 , 133 .

[0055] The base station 130 includes one or more radio transceivers 313 for wirelessly communicating with other entities of the radio communication network 100 (e.g., the UE 10). The transceiver 313 may therefore include a radio receiver and a transmitter for communicating over at least one air interface. For simplicity, only one radio transceiver 313 is shown, but it should be noted that in the case of more than one DU 132, 133, each DU may be configured with its own corresponding radio transceiver.

[0056] The base station 130 also includes logic 310 configured to communicate data with the UE 10 over a radio channel via a radio transceiver. The logic 310 may include a processing device 311, which includes one or more processors, microprocessors, data processors, coprocessors, and / or some other type of component that interprets and / or executes instructions and / or data. The processing device 311 may be implemented as hardware (e.g., a microprocessor, etc.) or a combination of hardware and software (e.g., a system on a chip (SoC), an application-specific integrated circuit (ASIC), etc.). The processing device 311 may be configured to perform one or more operations based on an operating system and / or various applications or programs.

[0057] Logic 310 may also include memory 312, which may include one or more memories and / or one or more other types of storage media. For example, memory 312 may include random access memory (RAM), dynamic random access memory (DRAM), cache, read-only memory (ROM), programmable read-only memory (PROM), flash memory, and / or some other type of memory. Memory 312 may include a hard disk (e.g., a magnetic disk, an optical disk, a magneto-optical disk, a solid-state disk, etc.).

[0058] The memory 312 is configured to store computer program code that can be executed by the processing device 311, wherein the logic 310 is configured to control the base station 130 to perform any method steps provided herein. The software defined by the computer program code may include applications or programs that provide functions and / or processes. The software may include device firmware, an operating system (OS), or various applications that can be executed in the logic 310.

[0059] It should be noted that separate logic may be configured for operating the CU 131 and the corresponding DUs 132, 133, but for simplicity only one entity providing the logic is shown. Figure 3B Shown in.

[0060] The base station 130 may further include or be connected to an antenna 314 connected to the radio transceiver 313, such as one antenna 314 for each DU 132, 133. Each antenna 314 may include an antenna array.

[0061] The base station 130 may also include one or more communication interfaces, such as an interface Xn operable for base station 130 to communicate with other base stations 140, and interfaces N2 and N3 operable for communicating with core network nodes. In addition, the base station 130 may be configured with a Uu interface 150 for wireless communication with a UE such as UE 10.

[0062] Figure 3B As shown in reference Figure 3A The functional elements described are provided as different functional blocks or objects within the CU 131 and the different DUs 132 and 133. Each of these units may contain its own logic, namely, logic 310A for controlling the CU 131, logic 310B for controlling the DU 132, and logic 310C for controlling the DU 133. At least the DUs 132 and 133 may include separate transceivers 314B and 314C, respectively. In addition, each DU 132 and 133 may include or be connected to a respective antenna 314B and 314C, respectively. As described above, each antenna 314B and 314C may include an antenna array.

[0063] In various embodiments, base station 130 is configured to perform the method steps outlined herein for execution in a base station.

[0064] Figure 4 Shown Figure 1 1. The diagram shows a first base station 130 on the left and a second base station on the right, both comprising respective CUs 131 and 141. Each base station 130, 140 also comprises a plurality of DUs, which are illustrated by the cells covered and served by the respective DUs. The first base station 130 covers an area 40 of the combined coverage or service area of ​​the DUs of the first base station 130, which may be connected to the area 40 of the combined coverage or service area of ​​the DUs of the first base station 130. Figure 1 1. The first notification area may be associated with a first notification area defined by access network 120. The first notification area may include or consist of the combined coverage area of ​​the DUs of first base station 130. The individual cells served by the DUs of first base station 130 are shown as hexagons with solid outlines. Accordingly, second base station 140 covers area 41 of the combined coverage or service area of ​​the DUs of second base station 140. The individual cells served by the DUs of second base station 140 are shown as hexagons with dashed outlines. Coverage area 41 may be associated with a second notification area defined by access network 120.

[0065] exist Figure 4In the illustrated scenario, UE 10 moves between different notification areas 40, 41 defined by the CU / DU configuration, as indicated by the dashed arrows. Specifically, UE 10 moves from a cell covered by a first DU 132 to a cell covered by a second DU 142, and then back to the coverage area 133 of another first DU 133 within the first DU. This situation would traditionally result in re-anchoring of UE 10. The UE context of UE 10 is thus moved from the old CU 131 controlling and / or serving DU 132 to the new CU 141 controlling and / or serving the new second DU 142. The network functions CU / AMF / SMF / UPF perform a path switch (including signaling on the NG-AP) to move the N2 and N3 tunnels connecting CUs 131, 141, respectively, to the core network 110. If the UE 10 has a mobility pattern that frequently crosses notification area boundaries, this will result in repeated triggering of the RAN notification area update procedure (i.e., re-anchoring), including signaling over the radio interface 150, and signaling within the network to handle path switching between anchor nodes in different RAN areas.

[0066] This document proposes a solution that allows the network 100 to mitigate the increased signaling for UE / RAN / CN in this specific or similar mobility mode. Figure 5 7 to 7 describe various aspects of this solution.

[0067] The solution reduces signaling by reducing the need to change anchor nodes when a UE 10 moves between cells belonging to different notification areas (e.g., RNAs). Rather than having statically defined notification areas, where a notification area update is required every time a UE 10 crosses a notification area boundary, the proposed solution involves dynamically updating the notification area for that particular UE 10 as soon as the UE 19 crosses a notification area boundary and thereby triggers a notification area update (e.g., RNA update), minimizing the risk of triggering further notification area updates, thereby avoiding further re-anchoring of the UE 10.

[0068] From the perspective of the wireless network 100, this is achieved by the following method: a method of operating a first base station 130 to configure a notification area 40, wherein the first base station 130 includes a first CU 131 and one or more first DUs 132, 133 controlled and / or served by the first CU. The method is performed by the first base station 130 and includes the following steps:

[0069] receiving first information identifying a notification area update from a second base station 140, the second base station including a second CU 141 and one or more second DUs 142, 143 controlled by the second CU,

[0070] wherein the first information is based on a message obtained in one of the second DUs 142 from the UE 10 configured with the first notification area 40 including the first base station;

[0071] establishing a connection between the first CU and the one second DU; and

[0072] The UE is configured with second information, where the second information identifies adding the second DU to the first notification area.

[0073] From the perspective of a UE 10, the object is achieved by: a method for operating a UE 10 to configure a notification area in a radio access network 120, the method comprising the following steps:

[0074] receiving information identifying a first notification area 40 including a first base station 130 , the first base station including a first CU 131 and one or more first DUs 132 , 133 controlled and / or served by the first CU;

[0075] receiving a signal from a second base station 140 identifying a second DU 142 that does not form part of the first notification area;

[0076] sending a first message to the second base station;

[0077] A second message including updated first notification area information is received from the second DU, the updated first notification area information identifying that the second DU is added to the first notification area.

[0078] This article presents two different overall implementations, however these overall implementations share several common features:

[0079] According to the first proposal, a DU 142 forming part of a base station 140 having a CU 141 may also be connected to another CU 131 (anchor). Thus, a DU can flexibly belong to different CUs and, therefore, different anchor nodes. Figure 5 and Figure 7A Describe the general and specific aspects of this first proposal.

[0080] According to a second proposal, a DU 142 forming part of a base station 140 having a CU 141 may be connected to another CU 131 (anchor) indirectly, for example via an Xn interface from the CU 141 to which the DU 142 is physically connected. Figure 6 and Figure 7B Describe the general and specific aspects of this first proposal.

[0081] Figure 5 Shown with Figure 4 The same scenario where the UE 10 moves, Figure 7A The associated signaling diagram is shown.

[0082] Figure 6 Also shown with Figure 4 The same scenario where the UE 10 moves, Figure 7B The associated signaling diagram is shown.

[0083] The difference between the two proposals lies in the connections established by the new DU 142, which are described in detail below. For common features between the proposals, the same reference numerals are used throughout the drawings and the following description.

[0084] UE 10 has a connection to a DU (e.g., DU 132) connected to a first CU 131 with a first base station 130. UE 10 is released from RRC connected mode to enter RRC_Inactive mode via process 701. In connection therewith, or beforehand, UE 10 is configured 700 with a first notification area 40 (e.g., first RNA 40). In some embodiments, first base station 130 may send a release message to UE 10, the release message including an information element having a cell list forming an RNA for UE 10.

[0085] While monitoring 702 signals from base stations, such as pilot signals or reference signals specified for cell reselection, the UE 10 then moves outside the initially configured first notification area 40 into an area covered by the DU 142 of the second base station 140 .

[0086] Since the second base station 140 does not form part of the first notification area 40, the UE 10 initiates a Radio Notification Area Update (RNA-U) procedure towards the new base station 140. This may include sending 703 a resume message 71 to the second DU 142. The notification area update procedure may involve signaling RNA update information 72 to the CU 141 that manages the new DU 142 and its associated cell DU-x that the UE 10 has entered.

[0087] Instead of performing a conventional context fetch 74 to the second CU 141 and a path switch from the old first CU 131 to the new second CU 141 towards the core network, the new second CU 141 notifies the first CU 131, acting as an anchor, of the triggered notification region update procedure triggered by the UE 10. Information 73 identifying the notification region update is thus signaled 707 from the new second CU 141 to the first CU 131, where the information 73 is received 708.

[0088] The first base station 130 is also configured to make a decision 709 to extend or modify its currently defined notification area 40 for the UE 10 by adding the new DU 142 to the list of DUs 132 , 133 connected to the first CU 131 .

[0089] Based on the determination to expand or modify the currently defined notification area 40 for the UE 10, the method further comprises establishing a connection between the first CU 131 and the second DU 142. Specifically, instead of including the second base station 140 itself along with all its DUs in the first notification area 40, only the DU 142 in question is included in the first notification area 40. In this way, a method for controlled modification of the first notification area 40 is obtained.

[0090] In following Figure 5 and Figure 7A In the proposed embodiment, the connection 50 between the first CU 131 and the one second DU 142 is established via an interface (e.g., F1). In one embodiment, this is achieved by adding an F1 interface 75 to the communication from the first CU 710 to the second DU 142 711. In this way, the second DU 132 now has a direct connection to both the first CU 131 and the second CU 141, as shown in FIG. Figure 5 The IP address (or other addressing information, such as a URL or FQDN) of the second DU 142 may be provided in the message 73 or through additional communications between the CU 131 and the CU 141 after the decision to include the DU 142 in the RNA 40 is made.

[0091] In following Figure 6 and Figure 7B In the proposed embodiment, the connection 60 is established via an inter-base station communication interface (e.g., Xn) between the first CU 131 and the second CU 141 and an interface (e.g., the existing F1 interface) between the second CU 141 and the one second CU 141. This may include sending 712 routing information 76 from the first CU 131 to be received 713 in the second CU 141 to set up and facilitate the connection 60.

[0092] In some embodiments, the connection includes an IP connection 50 between the first CU 131 and the second DU 142, or an IP connection 60 between the first CU 131 and the second CU 141. The IP connection can be configured by the first CU 131, or by the second DU 142 or the second CU 141. If a pre-configured IP connection is available, such as one established for a UE-specific notification area of ​​another UE, the first CU 131 can be configured to use routing information for the pre-configured IP connection. In various embodiments, the IP connection can be an IP tunnel, such as a secure IP tunnel.

[0093] Following both proposals, the UE 10 is then configured with second information 78 identifying the addition of the one second DU 142 to the first notification area 40. This may involve a communication 714 from the first CU 131 for reception 715 in the second DU 142, providing information 77 regarding the addition of the second DU 142 to the first notification area 40. Configuring the UE 10 with the second information 78 may also include sending updated notification area information 78 from the second DU 142 to the UE 10.

[0094] The second information 78 may identify the cell ID of the one second DU. This need not be specific, as the UE 10 may have already acquired the cell ID in communication with the second DU 142 when sending the resume message 71. Therefore, an alternative to specifically identifying the cell ID may include including a flag or code indicating the current cell ID in the second information.

[0095] In some embodiments, the second information 78 identifies an instruction instructing the UE 10 to add the second DU 142 to the first notification area. Thus, the UE 10 can be configured, via a flag or code in the second information, to add the second DU 142 or the cell it serves to the already stored first notification area 40. As described above, the instruction need not specifically identify the second DU 142, but rather can indicate the current cell to be added. The UE 10 can be configured to send a confirmation to the first CU 131 that the first notification area has been updated accordingly. This embodiment provides an alternative to fully updating the first notification area, thus involving less data transmission.

[0096] In some embodiments, the first base station 130, such as the first CU 131, may be controlled or configured to, in response to receiving the first information 73 identifying a notification area update, make a decision 709 to establish 75, 76 the connection 50, 60, or alternatively provide 74 UE context information for the UE 10 to the second base station 140. In some embodiments, the decision 709 may be based on recorded UE mobility data for the UE 10. In one embodiment, a control function in the logic 310 of the first base station 130 is operated to make a decision 709 to perform context retrieval or to establish a connection with the second DU 142 and include the second DU 142 in the first notification area 40. The control logic may be configured to take into account the mobility of the UE 10, such as the repeated or persistent presence of the UE 10 in the cell of the second DU 142, as determined by one or more rules or limits. Thus, the control functionality may be used to control the first CU 131 to establish the connection 50, 60 based on recorded UE mobility data, the UE mobility data identifying at least one or a predetermined combination of:

[0097] a) The mobility level does not exceed a mobility threshold level. In one embodiment, the mobility and mobility threshold may be given by a value for the mobile speed. The mobile speed of the UE 10 may be determined based on a report from the UE 10 or by positioning and speed determination performed in the network 100. This may enable the control function to selectively establish a connection 50, 60 with the second DU 142 in response to the speed not exceeding the speed threshold. In this way, if the UE 10 is determined to be traversing only cells served by the second DU 142, inappropriate expansion of the first notification area 40 may be avoided.

[0098] b) The number of DUs previously added to the first notification area 40 does not exceed the first threshold number. If this number does exceed the first threshold number, the user of the UE 10 may have an irregular or extensive mobility pattern, or the UE 10 may be continuously traveling and possibly stopping in areas covered by different cells. Therefore, the control function may determine that further expanding the first notification area would not be beneficial compared to dividing these areas into two or more notification areas.

[0099] c) the number of previously recorded connections of the UE 10 to the second DU 142 exceeds a second threshold number. The control function may therefore be configured to determine that the first notification area is to be extended only if the UE 10 has entered the cell of the second DU 142 more than a predetermined number of times (as given by the second threshold number of times).

[0100] d) the time period since the last recorded connection of the UE 10 to the second DU 142 does not exceed the first threshold time period. The control function may therefore be configured to determine that extending the first notification area will only occur if the UE 10 connects to the second DU 142 with a frequency such that the time elapsed since the last connection does not exceed the first threshold time period.

[0101] e) The time period since the last DU was added to the first RNA exceeds the second threshold time period. If the time period does exceed the second threshold time period, this may be caused by the user of UE 10 traveling or otherwise having an irregular or extensive mobility pattern. Therefore, the control function may determine that further expanding the first notification area would not be beneficial compared to dividing the area into two or more notification areas.

[0102] As soon as the UE 10 receives 717 the second information identifying the addition of the second DU 142 to the first notification area 40, the UE 10 may be released 718 back to RRC_Inactive, with the radio connection now suspended.

[0103] Various embodiments have been outlined herein involving configuring a UE-specific notification area such as an RNA. Except where expressly contradictory, the disclosed solutions and embodiments may be combined in any manner. Various embodiments within these embodiments are outlined in the following clause (C):

[0104] C1. A method of operating a first base station 130 to configure a first notification area 40, wherein the first base station 130 includes a first central unit CU 131 and one or more first distributed units DU 132, 133 controlled by the first CU, the method comprising the following steps:

[0105] receiving 708 first information 73 identifying a notification area update from a second base station 140, the second base station comprising a second CU 141 and one or more second DUs 142, 143 controlled by the second CU,

[0106] wherein the first information is based on a message 71 identifying a notification area update procedure obtained in a second DU 142 of the second DUs from a user equipment UE10 configured with a first notification area including the first base station;

[0107] establishing 710 , 712 a connection 50 , 60 between the first CU and the one second DU; and

[0108] The UE is configured 714 with second information 78, the second information identifying the addition of the one second DU to the first notification area.

[0109] C2. The method according to C1, wherein the step of establishing the connection includes configuring an IP connection.

[0110] C3. The method of C1, wherein establishing the connection comprises using routing information of a preconfigured IP connection.

[0111] C4. The method according to C2 or C3, wherein the IP connection is a secure IP tunnel.

[0112] C5. The method according to any one of C1 to C4, wherein an interface F1 between the first CU and the one second DU is established over the connection 50.

[0113] C6. A method according to any one of C1 to C4, wherein an interface F1 between the first CU and the one second DU is established on the connection 60, including an inter-base station communication interface Xn between the first CU and the second CU and an interface F1 between the second CU and the one second DU.

[0114] C7. A method according to any of the preceding clauses, wherein the step of configuring the UE comprises:

[0115] The one second DU is controlled to send a message 78 identifying updated notification area information to the UE.

[0116] C8. The method of any preceding clause, wherein the information identifying the first notification area excludes the second base station 140.

[0117] C9. The method according to any of the preceding clauses, the method comprising: in response to receiving the first information 73:

[0118] Controlling the first CU based on the recorded UE mobility data of the UE to:

[0119] Establishing the connection described in 75 and 76, or

[0120] The UE context information of the UE is provided 74 to the second base station.

[0121] C10. The method according to C9, wherein the first CU is controlled to establish the connection based on recorded UE mobility data, the UE mobility data identifying at least one or a predetermined combination of the following:

[0122] The mobility level does not exceed the mobility threshold level;

[0123] the number of DUs previously added to the first RNA does not exceed a first threshold number;

[0124] The recorded number of previous connections between the UE and the second DU exceeds a second threshold number;

[0125] a time period since the last recorded connection between the UE and the one second DU does not exceed a first threshold time period;

[0126] The time period since the last addition of DU to the first RNA exceeds a second threshold time period.

[0127] C11. The method according to any of the preceding clauses, wherein the second information identifies a UE-specific notification area for the UE.

[0128] C12. The method according to any of the preceding clauses, wherein the second information identifies a cell ID of the one second DU.

[0129] C13. The method according to any of the preceding clauses, wherein the second information identifies an instruction for the UE to add the one second DU to the first notification area.

[0130] C14. A method for operating a user equipment UE 10 to configure a notification area in a radio access network 120, the method comprising the steps of:

[0131] receiving 700 information identifying a first notification area 40 comprising a first base station 130, said first base station comprising a first central unit CU 131 and one or more first distributed units DU 132, 133 controlled by said first CU;

[0132] receiving 702 a signal from a second base station 140 identifying a second DU 142 that does not form part of the first notification area;

[0133] Sending 703 a first message indicating a notification area update process to the second base station;

[0134] A second message including updated notification area information 78 is received 717 from the second DU, the updated notification area information 78 identifying the addition of the second DU to the first notification area.

[0135] C15. The method according to C14, wherein the updated notification area information identifies a UE-specific notification area for the UE.

[0136] C16. The method according to C14 or C15, wherein the updated notification area information identifies a cell ID of the one second DU.

[0137] C17. The method according to C14 or C15, wherein the updated notification area information identifies an instruction for the UE to add the second DU to the first RNA.

[0138] C18. The method according to any one of C14 to C17, wherein the information identifying the first notification area does not identify the second base station 140.

Claims

1. A method of operating a first base station (130) to configure a first notification area (40), the first base station acting as an anchor node in the first notification area, wherein: The first base station (130) comprises a first central unit CU (131) and one or more first distributed units DU (132, 133) controlled by the first CU, and the method comprises the following steps: receiving (708) first information (73) identifying a notification area update from a second base station (140) not in the first notification area, the second base station comprising a second CU (141) and one or more second DUs (142, 143) controlled by the second CU, wherein the first information is based on a message (71) identifying a notification area update procedure obtained in one of the second DUs (142) from a user equipment UE (10) configured with the first notification area; establishing (710, 712) a connection (50, 60) between the first CU and the one second DU; and The UE is configured (714) with second information (78), the second information identifying the addition of the one second DU to the first notification area.

2. The method according to claim 1, wherein The step of establishing the connection includes configuring an IP connection.

3. The method according to claim 1, wherein The step of establishing the connection includes using routing information of a pre-configured IP connection.

4. The method according to claim 2 or 3, wherein: The IP connection is a secure IP tunnel.

5. The method according to claim 1, wherein An interface (F1) between the first CU and the one second DU is established over the connection (50).

6. The method according to claim 1, wherein An interface (F1) between the first CU and the one second DU is established on the connection (60), including an inter-base station communication interface (Xn) between the first CU and the second CU and an interface (F1) between the second CU and the one second DU.

7. The method according to claim 1, wherein The steps of configuring the UE include: The one second DU is controlled to send a message (78) identifying updated notification area information to the UE.

8. The method according to claim 1, wherein The information identifying the first notification area does not include the second base station (140).

9. The method according to claim 1, comprising: In response to receiving the first information (73): Controlling the first CU based on the recorded UE mobility data of the UE to: establishing (75, 76) said connection, or UE context information of the UE is provided (74) to the second base station.

10. The method according to claim 9, wherein: The first CU is controlled to establish the connection based on recorded UE mobility data, the UE mobility data identifying at least one or a predetermined combination of the following: The mobility level does not exceed the mobility threshold level; the number of DUs previously added to the first RNA does not exceed a first threshold number; The recorded number of previous connections between the UE and the second DU exceeds a second threshold number; a time period since the last recorded connection between the UE and the one second DU does not exceed a first threshold time period; The time period since the last addition of DU to the first RNA exceeds a second threshold time period.

11. The method according to claim 1, wherein The second information identifies a UE-specific notification area for the UE.

12. The method according to claim 1, wherein The second information identifies the cell ID of the one second DU.

13. The method according to claim 1, wherein The second information identifies an instruction for the UE to add the second DU to the first notification area.

14. A method for operating a user equipment (UE) (10) to configure a notification area in a radio access network (120), the method comprising the steps of: receiving (700) information identifying a first notification area (40) in which a first base station (130) serves as an anchor node, the first base station comprising a first central unit CU (131) and one or more first distributed units DU (132, 133) controlled by the first CU; receiving (702) a signal from a second base station (140) identifying a second DU (142) that does not form part of the first notification area; sending (703) a first message identifying a notification area update process to the second base station; A second message including updated notification area information (78) is received (717) from the second DU, the updated notification area information (78) identifying the addition of the second DU to the first notification area.

15. The method according to claim 14, wherein The updated notification area information identifies a UE-specific notification area for the UE.

16. The method according to claim 14 or 15, wherein: The updated notification area information identifies the cell ID of the one second DU.

17. The method according to claim 14 or 15, wherein: The updated notification area information identifies an instruction for the UE to add the second DU to the first RNA.

18. The method according to claim 14, wherein The information identifying the first notification area does not identify the second base station (140).

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