Interface framework for flexible function placement in wireless communication

Abstract

This application relates to an interface framework for flexible placement of functions in wireless communications. Example embodiments provide an enhanced interface framework for the flexible placement of User Equipment Control Plane (UE-CP) functions. The service-agnostic nature of the message exchange mechanism allows services such as UE-CP to be flexibly placed in logical / network nodes. Apparatus, methods, and computer programs are disclosed.

Description

Technical Field

[0001] This application generally relates to information technology. Some example embodiments of this application relate to providing an enhanced interface framework for flexibly placing User Equipment Control Plane (UE-CP) functionality. Background Technology

[0002] Base station decomposition can include a configuration where UE-CP functions (such as Radio Resource Control (RRC) and Mobility Functions for User Equipment (UE)) and common control plane functions (such as paging and broadcasting) are handled at the Central Unit (CU) of the base station, while the Distributed Unit (DU) located at the cell site can handle lower layers of communication protocols, such as Radio Link Control (RLC), Media Access Control (MAC), and Physical Layer (PHY). This decomposition introduces additional signaling between the CU and DU, resulting in suboptimal latency for latency-sensitive UEs. Summary of the Invention

[0003] This summary is provided to present a simplified version of the selection of concepts that will be further described in the detailed description below. This summary 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.

[0004] Example embodiments can improve resource allocation efficiency and reduce latency by dynamically selecting the optimal placement of UE-CP functions based on factors such as network load, proximity, or service requirements. These advantages are realized through the features of the independent claims. Further implementations are provided in the dependent claims, the specification, and the drawings.

[0005] According to a first aspect, an apparatus is provided. The apparatus is, for example, a network node. The apparatus 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 apparatus to at least: receive a message from the network node on a radio access network (RAN) interface, wherein the message includes a routing header; determine, based on the routing header of the message, whether the apparatus should process the message or forward the message to another network node; and process the message or forward the message to another network node based on said determination.

[0006] According to an example embodiment of the first aspect, the routing header includes an interface common field that identifies at least one of the following: user equipment (UE), service associated with the UE, cell for the UE, or public service.

[0007] According to an example embodiment of the first aspect, at least one memory and computer program code are configured, together with at least one processor, to enable the device to determine, based on at least one of a routing header or an interface common field, whether to process a message or to forward the message to a second device associated with the device.

[0008] According to an example embodiment of the first aspect, the message is a UE-specific message; one of the apparatus or the second apparatus performs a UE-control plane (UE-CP) function for the UE by processing radio resource control (RRC) for the UE; and at least one memory and computer program code are configured, together with at least one processor, to cause the apparatus to: determine, based on an interface common field, whether to forward the message to the second apparatus associated with the apparatus, based on the UE-CP function for the UE being performed by the apparatus; or to determine, based on an interface common field, whether to process the message by the apparatus, based on the UE-CP function for the UE being performed by the apparatus.

[0009] According to an example embodiment of the first aspect, wherein at least one memory and computer program code are configured together with at least one processor to enable the device to: in response to determining that a message should be forwarded to a second device associated with the device, select a second device associated with the device from a plurality of devices associated with the device based on an interface common field, the second device being configured to perform a UE-CP function for the UE.

[0010] According to an example embodiment of the first aspect, wherein at least one memory and computer program code are configured together with at least one processor to enable the device to: perform a UE control plane (UE-CP) function for all UEs in a cell of the device, determining, based on the cell, to forward a message to the second device associated with the device; or perform a UE-CP function for all UEs in a cell of the device, determining, based on the cell, to process a message by the device.

[0011] According to an example embodiment of the first aspect, at least one memory and computer program code are configured, together with at least one processor, to enable the device to process a UE context retrieval request by determining whether the UE context is stored in the device or in the second device based on whether the UE control plane (UE-CP) function for the UE is performed by a second device associated with the device or by the device itself.

[0012] According to an example embodiment of the first aspect, wherein at least one memory and computer program code are configured together with at least one processor to enable the device to: determine, based on a node local identifier included in a UE context retrieval request, whether the UE context is stored in the device or in a second device associated with the device, the node local identifier indicating whether the UE-CP function for the UE is performed by the second device or by the device.

[0013] According to an example embodiment of the first aspect, wherein at least one memory and computer program code are configured together with at least one processor to enable the device to: determine, based on location information stored in the device, whether the UE context is stored in the device or in a second device associated with the device, the location information indicating whether a UE-CP function for the UE is performed by the second device or by the device.

[0014] According to an example embodiment of the first aspect, at least one memory and computer program code are configured together with at least one processor to enable the device to: store location information in the device indicating whether the UE-CP function for the UE is performed by a second device or by the device itself.

[0015] According to an example embodiment of the first aspect, the routing header, together with the interface common fields, includes a network node identifier or functional module identifier that indicates the network node or functional module to process UE-specific messages.

[0016] According to the example embodiment of the first aspect, the message is not a UE-specific message; and the routing header includes a network node identifier or functional module identifier that indicates the network node or functional module to which the message is destined.

[0017] According to an example embodiment of the first aspect, the RAN interface is at least one of an F1 interface, an E1 interface, an Xn interface, or an NG interface; the apparatus is a central unit (CU) of a base station network node; and a portion of the message other than the routing header depends on the RAN service associated with the message.

[0018] According to an example embodiment of the first aspect, the routing header includes at least one of the UE identifier or cell identifier of the UE; the message is received on the RAN control plane (CP) interface; and at least one memory and computer program code are configured, together with at least one processor, to enable the device to determine, based on the UE identifier or cell identifier of the UE, whether a UE-CP function for the UE is executed in the device.

[0019] According to an example embodiment of the first aspect, the routing header includes an inactive radio network temporary identifier (I-RNTI) which includes an indication that UE context information is stored in the device; and at least one memory and computer program code are configured, together with at least one processor, to cause the device to: in response to a message, transmit the UE context information according to the indication.

[0020] According to a second aspect, an apparatus is provided. The apparatus is, for example, a distributed unit (DU) associated with a base station central unit (CU). The apparatus may include: at least one processor; and at least one memory, including computer program code; the at least one memory and the computer program code are configured, together with the at least one processor, to cause the apparatus to at least: receive a message from a user equipment (UE) on a radio access network (RAN) interface; determine, based on whether the apparatus is configured to perform UE control plane (UE-CP) functions for the UE, whether the apparatus should process the message or forward the message to a network node, wherein the apparatus is associated with a network node and configured to process radio resource control (RRC) for the UE; and process the message or forward the message to the network node based on said determination.

[0021] According to an example embodiment of the second aspect, at least one memory and computer program code are configured, together with at least one processor, to enable the apparatus to: receive a second message from a network node on a RAN interface, wherein the second message is a UE-specific message and includes a routing header that includes an interface common field identifying at least one of the following: user equipment (UE), a service associated with the UE, or a cell associated with the UE; and to process the UE-specific message based on the interface common field by performing a UE-CP function for the UE in the apparatus.

[0022] According to an example embodiment of the second aspect, at least one memory and computer program code are configured, together with at least one processor, to enable the apparatus to: receive a third message from a network node on a RAN interface, wherein the third message is not a UE-specific message and includes a network node identifier or functional module identifier indicating the network node or functional module to which the message is destined; and process the third message in the apparatus.

[0023] According to an example embodiment of the second aspect, the routing header of a UE-specific message, together with interface common fields, includes a network node identifier or functional module identifier that indicates the network node or functional module to which the UE-specific message is destined.

[0024] According to an example embodiment of the second aspect, at least one memory and computer program code are configured, together with at least one processor, to enable the device to determine whether to process a message or to forward a message to a network node, based on whether the device is configured to perform UE-CP functions for all UEs in a cell associated with the UE.

[0025] According to an example embodiment of the second aspect, at least one memory and computer program code are configured, together with at least one processor, to enable the device to: send UE context information to a network node in response to a UE context retrieval request, wherein the UE context information is sent together with common interface fields of the UE.

[0026] According to an example embodiment of the second aspect, at least one memory and computer program code are configured together with at least one processor to enable the device to: perform a UE-CP function for the UE and store UE context information associated with the UE in the device.

[0027] According to an example embodiment of the second aspect, the RAN interface is at least one of an F1 interface, an E1 interface, an Xn interface, or an NG interface; the apparatus is a distributed unit (DU) of a base station network node; and a portion of the message other than the routing header depends on the RAN service associated with the message.

[0028] According to an example embodiment of the second aspect, the message is an RRC recovery request; and at least one memory and computer program code are configured, together with at least one processor, to enable the device to: determine, based on the message, whether a UE-CP function for the UE is executed in the device.

[0029] According to an example embodiment of the second aspect, the message includes an inactive radio network temporary identifier (I-RNTI) which includes an indication that UE context information is stored in the device; and at least one memory and computer program code are configured, together with at least one processor, to cause the device to: in response to the message, transmit the UE context information according to the indication.

[0030] According to a third aspect, a UE device includes: 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 UE device to at least: receive a Radio Resource Control (RRC) message from a first network node, the RRC message including an indication of whether the first network node is configured to perform a UE Control Plane (UE-CP) function for the UE device, or whether a second network node different from the first network node is configured to perform a UE-CP function for the UE device; based on the UE device switching from an inactive mode to a connected mode, send a message including an indication of whether the first network node is configured to perform a UE-CP function for the UE device, or whether a second network node is configured to perform a UE-CP function for the UE device; and communicate with a third network node in the connected mode, the third network node having acquired UE context information for the UE device based on the sent indication, wherein the third network node is the first network node or another network node.

[0031] According to the example embodiment of the third aspect, the RRC message received by the UE device is a message associated with switching the UE device to an inactive mode; and the message sent by the UE device based on the UE device switching from an inactive mode to a connected mode is an RRC recovery request.

[0032] According to an example embodiment of the third aspect, the RRC message received by the UE device includes an Inactive Radio Network Temporary Identifier (I-RNTI), which includes an indication that UE context information is stored in a first network node, and the message sent by the UE device based on the UE device switching from inactive mode to connected mode includes the I-RNTI.

[0033] According to an example embodiment of the third aspect, based on the UE device switching from an inactive mode to a connected mode, a message is sent to the last known network node performing UE control plane (UE-CP) functions for the UE device.

[0034] According to the fourth aspect, a method may include: receiving a message from a network node on a radio access network (RAN) interface, wherein the message includes a routing header; determining, based on the routing header of the message, whether the means should process the message or forward the message to another network node; and processing the message or forwarding the message to another network node based on the determination.

[0035] According to an example embodiment of the fourth aspect, the routing header includes an interface common field that identifies at least one of the following: user equipment (UE), service associated with the UE, cell for the UE, or public service.

[0036] According to an example embodiment of the fourth aspect, the method may further include: determining, based on at least one of a routing header or an interface common field, whether to process the message or to forward the message to a second device associated with the device.

[0037] According to an example embodiment of the fourth aspect, the message is a UE-specific message; one of the apparatus or the second apparatus performs a UE-control plane (UE-CP) function for the UE by processing radio resource control (RRC) for the UE; and the method may further include: determining, based on an interface common field, whether to forward the message to the second apparatus associated with the apparatus, based on the UE-CP function for the UE being performed by the apparatus; or determining, based on an interface common field, whether to process the message by the apparatus, based on the UE-CP function for the UE being performed by the apparatus.

[0038] According to an example embodiment of the fourth aspect, the method may further include: in response to determining that a message should be forwarded to a second device associated with the device, selecting a second device associated with the device from a plurality of devices associated with the device based on an interface common field, the second device being configured to perform a UE-CP function for the UE.

[0039] According to an example embodiment of the fourth aspect, the method may further include: determining, based on the cell, to forward a message to the second device associated with the device, based on the cell, that a second device associated with the device is configured to perform a UE control plane (UE-CP) function for all UEs in a cell of the device; or determining, based on the cell, that the device processes the message, based on the cell, that the UE-CP function for all UEs in a cell of the device is performed by the device.

[0040] According to an example embodiment of the fourth aspect, the method may further include: processing a UE context retrieval request by determining whether the UE context is stored in the device or in the second device based on whether the UE control plane (UE-CP) function for the UE is performed by a second device associated with the device or by the device.

[0041] According to an example embodiment of the fourth aspect, the method may further include: determining whether the UE context is stored in the device or in a second device associated with the device based on a node local identifier included in the UE context retrieval request, wherein the node local identifier indicates whether the UE-CP function for the UE is performed by the second device or by the device.

[0042] According to an example embodiment of the fourth aspect, the method may further include: determining, based on location information stored in the device, whether the UE context is stored in the device or in a second device associated with the device, wherein the location information indicates whether the UE-CP function for the UE is performed by the second device or by the device.

[0043] According to an example embodiment of the fourth aspect, the method may further include: storing location information in the device that indicates whether the UE-CP function for the UE is performed by a second device or by the device itself.

[0044] According to an example embodiment of the fourth aspect, the routing header, together with the interface common fields, includes a network node identifier or functional module identifier that indicates the network node or functional module to process UE-specific messages.

[0045] According to an example embodiment of the fourth aspect, the message is not a UE-specific message; and the routing header includes a network node identifier or functional module identifier that indicates the network node or functional module to which the message is destined.

[0046] According to an example embodiment of the fourth aspect, the RAN interface is at least one of an F1 interface, an E1 interface, an Xn interface, or an NG interface; the apparatus is a central unit (CU) of a base station network node; and a portion of the message other than the routing header depends on the RAN service associated with the message.

[0047] According to an example embodiment of the fourth aspect, the routing header includes at least one of the UE identifier or the cell identifier of the UE; the message is received on the RAN control plane (CP) interface; and the method may further include: determining whether a UE-CP function for the UE is executed in the device based on the UE identifier or the cell identifier of the UE.

[0048] According to an example embodiment of the fourth aspect, the routing header includes an inactive radio network temporary identifier (I-RNTI) that includes an indication that UE context information is stored in the device; and the method may further include: in response to a message, sending the UE context information according to the indication.

[0049] According to the fifth aspect, a method may include: receiving a message from a user equipment (UE) on a radio access network (RAN) interface; determining, based on whether the device is configured to perform UE control plane (UE-CP) functions for the UE, whether the device should process the message or forward the message to a network node, wherein the device is associated with a network node and configured to process radio resource control (RRC) for the UE; and processing the message or forwarding the message to the network node based on the determination.

[0050] According to an example embodiment of the fifth aspect, the method may include: receiving a second message from a network node on a RAN interface, wherein the second message is a UE-specific message and includes a routing header that includes an interface common field that identifies at least one of the following: a user equipment (UE), a service associated with the UE, or a cell associated with the UE; and processing the UE-specific message based on the interface common field by performing a UE-CP function for the UE in the apparatus.

[0051] According to an example embodiment of the fifth aspect, the method may include: receiving a third message from a network node on a RAN interface, wherein the third message is not a UE-specific message and includes a network node identifier or functional module identifier, the network node identifier or functional module identifier indicating the network node or functional module to which the message is destined; and processing the third message in an apparatus.

[0052] According to an example embodiment of the fifth aspect, the routing header of a UE-specific message, together with an interface common field, includes a network node identifier or functional module identifier that indicates the network node or functional module to which the UE-specific message is destined.

[0053] According to an example embodiment of the fifth aspect, the method may include: determining whether the device should process a message or forward a message to a network node based on whether the device is configured to perform UE-CP functionality for all UEs in a cell associated with the UE.

[0054] According to an example embodiment of the fifth aspect, the method may include: in response to a UE context retrieval request, sending UE context information to a network node, wherein the UE context information is sent together with common interface fields of the UE.

[0055] According to an example embodiment of the fifth aspect, the method may include: storing UE context information associated with the UE in the device based on the device performing a UE-CP function for the UE.

[0056] According to an example embodiment of the fifth aspect, the RAN interface is at least one of an F1 interface, an E1 interface, an Xn interface, or an NG interface; the apparatus is a distributed unit (DU) of a base station network node; and a portion of the message other than the routing header depends on the RAN service associated with the message.

[0057] According to an example embodiment of the fifth aspect, the message is an RRC recovery request; and the method may include: determining, based on the message, whether a UE-CP function for the UE is executed in the device.

[0058] According to an example embodiment of the fifth aspect, the message includes an inactive radio network temporary identifier (I-RNTI) that includes an indication that UE context information is stored in the device; and the method may include: in response to the message, sending the UE context information according to the indication.

[0059] According to a sixth aspect, a method may include: a UE device receiving a Radio Resource Control (RRC) message from a first network node, the RRC message including an indication of whether the first network node is configured to perform a UE Control Plane (UE-CP) function for the UE device, or whether a second network node different from the first network node is configured to perform a UE-CP function for the UE device; based on the UE device switching from an inactive mode to a connected mode, the UE device sending a message including an indication of whether the first network node is configured to perform a UE-CP function for the UE device, or whether the second network node is configured to perform a UE-CP function for the UE device; and the UE device communicating in the connected mode with a third network node, the third network node having obtained UE context information for the UE device based on the sent indication, wherein the third network node is the first network node or another network node.

[0060] According to the example embodiment of the sixth aspect, the RRC message received by the UE device is a message associated with switching the UE device to an inactive mode; and the message sent by the UE device based on the UE device switching from an inactive mode to a connected mode is an RRC recovery request.

[0061] According to an example embodiment of the sixth aspect, the RRC message received by the UE device includes an inactive radio network temporary identifier (I-RNTI), which includes an indication that UE context information is stored in a first network node, and the message sent by the UE device based on the UE device switching from inactive mode to connected mode includes the I-RNTI.

[0062] According to an example embodiment of the sixth aspect, based on the UE device switching from an inactive mode to a connected mode, a message is sent to the last known network node performing UE control plane (UE-CP) functions for the UE device.

[0063] According to a seventh aspect, an apparatus may include components for performing the methods of the fourth, fifth, or sixth aspect. The apparatus may also include components for performing any example embodiments of the methods of the fourth, fifth, or sixth aspect as provided in the specification and / or claims.

[0064] According to the eighth aspect, a computer program, computer program product, or (non-transitory) computer-readable medium is disclosed. The computer program, computer program product, or (non-transitory) computer-readable medium may include instructions for causing the apparatus to perform at least the method according to the fourth, fifth, or sixth aspect. The computer program may also include instructions for causing the apparatus to perform any of the example embodiments provided in the specification and / or claims.

[0065] Many of the accompanying features will become easier to understand when considered in conjunction with the following detailed description with reference to the accompanying drawings. Attached Figure Description

[0066] The accompanying drawings are included to provide a further understanding of the exemplary embodiments and form part of this specification. The drawings illustrate exemplary embodiments and, together with the description, help to explain the exemplary embodiments. In the drawings: Figure 1 An example of a base station architecture with flexible placement of UE-CP functionality is shown according to an example embodiment.

[0067] Figure 2 An example of a network node forwarding or processing interface messages according to an example embodiment is shown.

[0068] Figure 3 An example of a CU forwarding or processing interface messages according to an example embodiment is shown.

[0069] Figure 4 An example of a CU forwarding or processing interface messages according to an example embodiment is shown, having UE-CP functionality in the CU and UE-CP functionality in the DU.

[0070] Figure 5 An example of the initial access procedure for a UE is shown according to an example embodiment when the UE-CP function for the UE is in the DU.

[0071] Figure 6 An example of the initial access procedure for a UE is shown according to an example embodiment when the UE-CP function for the UE is in the CU.

[0072] Figure 7 An example of an intra-NB handover process for a UE (i.e., handover between two DUs of a network node) is shown according to an example embodiment when the UE-CP function for the UE is in a DU.

[0073] Figure 8 An example of the intraNB handover process of the UE when the UE-CP function for the UE is in the CU is shown according to an example embodiment.

[0074] Figure 9An example of an inter-NB handover process for a UE when the UE-CP function for the UE is in the DU is shown according to an example embodiment.

[0075] Figure 10 An example of the NB-to-NB handover process of a UE is shown according to an example embodiment when the UE-CP function for the UE is in the CU.

[0076] Figure 11 An example of a process for transitioning a UE from an inactive state to a connected state when the UE-CP function for the UE is in the DU, according to an example embodiment, is shown.

[0077] Figure 12 An example of a process for transitioning a UE from an inactive state to a connected state when the UE-CP function for the UE is in the CU, according to an example embodiment, is shown.

[0078] Figure 13 An example of a device configured to practice one or more example embodiments is shown; Figure 14 An example of a message interface method in a communication network according to an example embodiment is shown; Figure 15 A second example of a message interface method in a communication network according to an example embodiment is shown; Figure 16 A third example of a message interface method in a communication network according to an example embodiment is shown.

[0079] In the accompanying drawings, the same reference numerals are used to denote the same parts. Detailed Implementation

[0080] 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 the present example and is not intended to represent the only form in which the present example can be constructed or utilized. This description illustrates the functionality of the example and the possible sequences of operations for constructing and operating the example. However, the same or equivalent functionality and sequences can be implemented through different examples.

[0081] As used herein, the term "communication network" refers to a network that conforms to any suitable communication standard, such as New Radio (NR), Long Term Evolution (LTE), LTE-A Advanced (LTE-A), Wideband Code Division Multiple Access (WCDMA), High-Speed ​​Packet Access (HSPA), Narrowband Internet of Things (NB-IoT), etc. Furthermore, communication between terminal devices and network devices in a communication network can be performed according to any suitable generation of communication protocol, including but not limited to first-generation (1G), second-generation (2G), 2.5G, 2.75G, third-generation (3G), fourth-generation (4G), 4.5G, fifth-generation (5G), 5.5G, sixth-generation (6G) communication protocols and / or any other currently known or future-developed protocols. Embodiments of this disclosure can be applied to various communication systems. Given the rapid development in communications, there will naturally be future types of communication technologies and systems that can implement this disclosure. The scope of this disclosure should not be limited to the aforementioned systems.

[0082] As used herein, the term "network device" refers to a node in a communications network through which terminal devices access the network and receive services. Network devices can refer to base stations (BS) or access points (APs), such as nodeB (NodeB or NB), evolved NodeB (eNodeB or eNB), NR NB (also known as gNB), remote radio unit (RRU), radio head (RH), remote radio head (RRH), repeater, integrated access and backhaul (IAB) node, low-power node (such as femtoseconds, picoseconds), non-terrestrial network (NTN) or non-terrestrial network equipment (such as satellite network equipment, low Earth orbit (LEO) satellites and geostationary Earth orbit (GEO) satellites), aircraft network equipment, etc., depending on the terminology and technology applied. In some example embodiments, the radio access network (RAN) split architecture includes a centralized unit (CU) and a distributed unit (DU) at the IAB donor node. An IAB node includes a mobile terminal (IAB-MT) portion that behaves like a UE to its parent node, and the DU portion of the IAB node behaves like a base station to the next-hop IAB node.

[0083] The term "terminal device" refers to any terminal device capable of wireless communication. As an example and not a limitation, a terminal device may also be referred to as a communication device, user equipment (UE), subscriber station (SS), portable subscriber station, mobile station (MS), or access terminal (AT). Terminal devices can include, but are not limited to, mobile phones, cellular phones, smartphones, Voice over IP (VoIP) phones, wireless local loop phones, tablets, wearable terminal devices, personal digital assistants (PDAs), portable computers, desktop computers, image acquisition terminal devices (such as digital cameras), gaming terminal devices, music storage and playback devices, in-vehicle wireless terminal devices, wireless endpoints, mobile stations, laptop embedded devices (LEEs), laptop-mounted devices (LMEs), USB dongles, smart devices, wireless customer premises equipment (CPEs), Internet of Things (IoT) devices, watches or other wearable devices, head-mounted displays (HMDs), vehicles, drones, medical devices and applications (e.g., remote surgery), industrial devices and applications (e.g., robots and / or other wireless devices operating in the context of industrial and / or automated processing chains), consumer electronics devices, devices operating on commercial and / or industrial wireless networks, etc. The terminal device may also correspond to the mobile terminal (MT) portion of an IAB node (e.g., a relay node). In the following description, the terms "terminal device," "communication device," "terminal," "user equipment," and "UE" are used interchangeably.

[0084] Figure 1 An example base station architecture with flexible placement of UE-CP functionality is shown according to an example embodiment. To address the high latency issue of latency-sensitive user equipment (UE), greater flexibility has been proposed for handling control plane (CP) services (common functions such as cell service, nodeB (NB) service, and UE control plane (UE-CP) service).

[0085] While there are significant advantages to handling public / NB-CP services in a central node (such as a central unit (CU)), placing the UE-CP at the cell site would enhance radio resource control (RRC) performance for latency-sensitive UEs. However, there are certain limitations to placing the UE-CP at the cell site due to the architecture of the decomposed system using a CU and one or more cell site distributed units (DUs).

[0086] For example, because cell sites (DUs) have limited size, cell site (DU) processing capacity cannot be shared, unlike centralized (typically cloud-based) CUs. Additionally, DUs may have a very large number of cells and UEs, so processing UE-CP functions for all UEs locally at the DU may exceed the capacity of the local processor / computer. Furthermore, periodically expanding cell site (DU) capacity may be very inefficient or even impossible.

[0087] Given the above considerations, in terms of the user plane (UP) and CP, the ability to handle some high-performance UEs (slices or enterprises) located close to the UE location can open up new opportunities for network operators. To achieve these goals, flexible UE-CP placement options and mechanisms have been proposed. For example, CP instances can provide any public / cell CP or UE-CP service and can be flexibly placed in a central cloud (or CU, to achieve pooling gain and capacity) or at a cell site (DU). CP / UE-CP placement can be based on UE capabilities, UE requirements, and network cloud capacity at the central location and cell site.

[0088] In 5G, interface protocols such as F1AP depend on service / function layers such as RRC or Radio Resource Management (RRM). Any changes to services / procedures / functions related to UE context management (including resource allocation) or RRC messages will result in changes to F1AP. In other words, the underlying service layers that control RAN functions are not entirely independent of the interfaces that serve these layers, leading to strong coupling between the interfaces and network service specifications.

[0089] This coupling results in a rigid RAN architecture because the current 5G interface specifications cannot accommodate any changes in function placement (e.g., performing RRC functions in the DU instead of the CU). Therefore, a service-agnostic interface approach is needed to accommodate flexible placement of CP / UE-CP functions at the DU or CU.

[0090] As mentioned above, Figure 1 An example of a decomposed architecture is shown, where UE-CP services can be provided by a centralized CU or by one of the DUs associated with the CU. Figure 1 In the example, nodeB 100 includes CU 102 and two DUs (104 and 106). As shown in the figure, CU 102 is configured to perform UE-CP and NB-CP functions. Additionally, DU 106 is configured to perform UE-CP functions, while DU 104 is not configured to perform UE-CP functions.

[0091] Since both CU 102 and DU 106 are configured for UE-CP functionality, the nodeB 100 support for UE-CP functionality can be flexibly placed in either CU 102 or DU 106, for example, on a per-UE basis based on requirements, computing resources, or other factors. Figure 1 The interfaces shown represent the interface specifications currently used in 5G, namely the F1-C interface between CU 102 and each DU (104 and 106), the Ng-C interface from the network to nodeB 100, and the Xn-C interface to another nodeB 108.

[0092] nodeB 108 is shown to have a non-decompositional architecture, where both NB-CP and UE-CP functions are centrally executed and DU is not used. Therefore, Figure 1 The example illustrates the current state of the decomposition configuration, including both monoliths and decomposed nodeBs within the same network. For example... Figure 1 As shown in nodeB 100, the problem with flexibly placing the UE-CP is that the requirements / specifications for the RAN interface (F1-C, NG-C, XN-C, etc.) are different depending on whether the UE-CP is in the central cloud / CU or the DU cell site.

[0093] To address this issue, this disclosure describes a sufficiently flexible interface design solution to accommodate three scenarios: (i) the UE-CP is in the CU (Central Cloud); (ii) the UE-CP is in the DU (Cell Site); and (iii) the nodeB is a monolithic / non-decomposition design without a DU (e.g., Figure 1 (NodeB 108). The associated problem is tracking the last UE-CP / context processing node when the UE is in an inactive state (e.g., RRC_INACTIVE state).

[0094] In other words, the process of a UE entering an inactive state includes the storage of UE context information by the UE-CP function. Therefore, the flexible placement of the UE-CP function results in a flexible location for the stored UE context, depending on the location where the last UE-CP function for that UE was executed (e.g., CU or DU). Thus, a means of locating the stored UE context is required.

[0095] In 5G, the Inactive Radio Network Temporary Identifier (I-RNTI) identifies a UE in the RRC_INACTIVE state. The I-RNTI contains information about the last gNB or equivalently the last gNB-CU-CP that owned / stored the UE context. Some embodiments of this disclosure include using the I-RNTI framework to further include a node-local identifier that indicates the location of the last CU or DU that owned / stored the context information of a UE with flexible location UE-CP functionality.

[0096] Embodiments of this disclosure may include the use of service-agnostic RAN interfaces instead of more strictly defined service-specific interfaces such as F1, E1, Xn, and NG. To this end, embodiments of this disclosure employ a generic interface message structure of [{function message}, header}] for various RAN services. The function message depends on the RAN service, such as mobility, RRC, or non-access stratum (NAS). The header is processed by each receiving network node, which determines whether to process or forward the function message based on the header content.

[0097] Furthermore, embodiments of this disclosure may include the use of a UE identifier (UE-ID), which is used in the context of UE-CP placement specific to a particular UE. That is, when the UE-CP function is flexibly placed in a CU or DU, using the UE-ID in the header of an interface message will enable the interface message to be routed to the specific node (CU or DU) performing the UE-CP function for that particular UE. In other embodiments, UE-CP placement is cell-based, such that all UEs in a first cell have UE-CP functions performed in a CU, and in another cell, all UEs have UE-CP functions performed, for example, at a DU.

[0098] In some embodiments of this disclosure, the I-RNTI is modified to include not only the nodeB identifier (NB-ID) of the nodeB that last owned / stored the UE context of the UE, but also an NB local identifier indicating whether the UE context in that nodeB is stored in a CU or a DU. For example, the NB local identifier of the modified I-RNTI may be a single bit indicating whether the UE-CP for the UE is stored in a DU or a CU in the nodeB identified by the NB-ID portion of the I-RNTI.

[0099] In other embodiments of this disclosure, to avoid altering the I-RNTI due to its limited size, the location of the UE-CP / UE context information of a UE transitioning to an "inactive" state is stored in the CU of the last nodeB serving the UE. In such embodiments, procedures can be defined to locate the UE context information and / or the node performing UE-CP functions for the UE within the last nodeB serving the UE. That is, when the UE is in a connected or inactive state, the location of the node (i.e., CU or DU) performing UE-CP functions for the UE can be stored in the network control plane, in the nodeB currently serving the UE or the last nodeB serving the UE, or in another location where the location can be queried.

[0100] Figure 2 An example of a network node forwarding or processing interface messages according to an example embodiment is shown. Figure 2 The interface messages shown can be classified as source messages (SM) or forwarded messages (FM). Figure 2 The messages shown are intended only to illustrate the functionality of the described interface messaging mechanism and do not necessarily correspond to any actual signaling. Figure 2 The network nodes shown can represent network nodes, entities, and / or functions.

[0101] Figure 2 The diagram illustrates message transmission between nodes A 202, B 204, and C 206. Nodes A and C can represent any network node in the network communication system. Initially, node A 202 sends a source message SM 210 to node B 204. SM 210 includes a header identifying node B as the destination of SM 210 and... Figure 2 The image shows the function message of {message}.

[0102] When a network node / function (i.e., DU, RAN-CP, RAN-UP, NB, or Access and Mobility Function (AMF)) sends a source message, it means that the sending node / function initiated the message. The source node / function can establish header content. For example, a node / function can send a "handover request" message with header fields, which enables intermediate nodes to route the message to the target node for handover.

[0103] SM 210 is the source message because it was sent and initiated by node A 202. Because the header of SM 210 indicates that node B 204 is the destination of SM 210, node B 204 receives and processes SM 210 in step 212. Figure 2 The following shows node A 202 sending SM 214 to node B 204. Similar to SM 210, SM 214 is the source message because it was sent and initiated by node A 202.

[0104] However, unlike SM 210, SM 214 includes a header indicating that node C 206 is the destination of the message, and Figure 2 The function message is shown as {message}. Therefore, upon receiving SM 214, node B 204 forwards the message in step 216. To forward the message, node B 204 generates FM 218 with the same content as SM 214, that is, a header and function message that identifies node C 206 as the destination.

[0105] Upon receiving FM 218, node C 206 processes the message in step 220 because node C is identified as the destination of the message in the header of FM 218. When a network node / function sends a forwarded message, this means that the node / function acts as a router / forwarder / intermediate node for the message between the source processing node / function and the destination processing node / function. Figure 2 In the example, node B acts as an intermediate node that forwards SM 214 to node C 206.

[0106] The destination node / function of a message is the final processing point for the function message. For example, a destination node / function can become a source node / function when it responds to a request from a source node / function. For instance, the target node for a handover can send a "handover confirmation" message to the requesting source node.

[0107] like Figure 2 As shown, the interface messages in embodiments of this disclosure may include a consistent structure, which includes a header and service / function messages. The header field identifying the destination node / function of the message may contain different information depending on the service / function message. For example, in an embodiment where UE-CP placement is performed per UE, the header field may include a Node B identifier (e.g., NB ID), a source base station identifier (e.g., Cell Global Identifier CGI), a target base station identifier (e.g., Cell Global Identifier CGI), a cell identifier (e.g., Physical Cell Identifier PCI), an Access and Mobility Management Function identifier (e.g., AMF ID), and / or a User Equipment identifier (e.g., UE ID).

[0108] The header fields are generated by the source node / function and copied in any subsequent forwarded messages required to send the message to the target node / function. The header contains enough information for any receiving node to decide whether and on which outgoing interface / route to forward the message. One advantage of embodiments of this disclosure is the service-agnostic nature of the message exchange mechanism, which allows services such as UE-CP to be flexibly placed in logical / network nodes.

[0109] In other words, the message exchange mechanism of this disclosure does not depend on a specific service performed by a specific node, because messages can be flexibly addressed and routed to the appropriate service or node, regardless of the location of that service or node. In embodiments of this disclosure, changes to services / functions such as RRC do not result in any changes to the message interface mechanism, because messages are carried as transparent containers.

[0110] Table 1 below shows examples of header fields that can be used in embodiments of this disclosure. For each type of destination node, the header fields may include different information depending on whether the message is UE-specific or NB-specific. UE-specific messages are messages that include functional messages related to the services of a particular UE. On the other hand, NB-specific messages are higher-level messages related to nodeB-level functions / services.

[0111] Table 1

[0112] In Table 1, if there is flexible and UE-specific placement of functionality supported in the network, cell, or destination node, the header field of a UE-specific message may include the UE-ID. For example, a message with a DU as the destination node may have a header field that includes the CGI or DU ID of the destination DU. Additionally, if the message is UE-specific and if UE-CP functionality can be flexibly placed for each UE, the header field may include the UE's UE ID to allow the message to be routed to the node performing the UE-CP functionality for that UE.

[0113] While Table 1 illustrates one example of an embodiment of this disclosure, other header structures may also be used to properly route UE-specific messages to flexibly located functions, such as UE-CP. For example, if the information indicates the location of a particular UE's UE-CP, a service ID or cell ID may be provided instead of the UE-ID as shown in Table 1.

[0114] Figure 3 An example of a CU forwarding or processing interface messages using the header structure shown in Table 1 is illustrated. Figure 3 In the example, the UE-CP function is performed by the DU. Figure 3 The RAN-CP 304 shown can be, for example, a CU with two associated DUs (DU-1 302 and DU-2 310). Initially, DU-1 302 sends an NB-specific message 312 to the RAN-CP 304.

[0115] Because the header of NB-specific message 312 indicates RAN-CP 304 as the message's destination, RAN-CP 304 processes the message in step 314. Next, DU-1 302 sends UE-specific message 316 to RAN-CP 304. The header of UE-specific message 316 includes the CGI of the neighboring NB 306 and the UE-ID. Accordingly, upon receiving UE-specific message 316, RAN-CP 304 determines in step 318 that the message should be forwarded to the neighboring NB 306.

[0116] Forwarded message 320 has the same header as the source message (UE-specific message 316) and is sent to the neighboring NB 306. Next, in Figure 3 In the example, neighboring NB 306 sends an NB-specific message 322 addressed to RAN-CP 304. That is, the header of NB-specific message 322 indicates the CGI of RAN-CP 304 as the message's destination. Therefore, RAN-CP 304 processes NB-specific message 322 in step 324.

[0117] exist Figure 3 In the example, UE-CP functionality can be flexibly placed for each UE, and the neighboring NB 306 sends a UE-specific message 326 to RAN-CP 304. The header of the UE-specific message 326 includes the UE-ID or another indicator indicating where the UE-CP functionality for the relevant UE is located. Using the UE-ID or the other indicator, RAN-CP 304 determines whether to execute the UE-CP functionality for the relevant UE in DU-1 302.

[0118] Therefore, in step 328, RAN-CP 304 forwards UE-specific message 326 to DU-1 302 by sending forwarded message 330. Finally, in Figure 3 In the example, UE-specific message 332 is sent from DU-1 302 to RAN-CP 304. The header of UE-specific message 332 includes the UE-ID or another interface common indicator (such as service ID or cell ID) indicating where the UE-CP function for the relevant UE is located. Using the UE-ID or this other indicator, RAN-CP 304 determines to execute the UE-CP function for the relevant UE in DU-2 310. Then, in step 334, RAN-CP 304 forwards UE-specific message 332 to DU-2 310 by sending forwarded message 336.

[0119] Figure 4An example of processing interface messages in a network is shown, where UE-CP functions for some UEs are performed in CU (RAN-CP 404), and UE-CP functions for other UEs are performed in DU-2 408. DU-1 402 and DU-2 408, as well as RAN-CP 404, correspond to a single nodeB station (NB-1 400). Figure 4 Some of the message interactions in the examples are similar to Figure 3 The message interactions in the examples are different from those in the CU / RAN-CP 404, while other message interactions are different because some UE-CP functions are reserved and executed in CU / RAN-CP 404.

[0120] For example, the NB-specific message 412 sent by DU-1 402 and processed by RAN-CP 404 in step 414 is similar to Figure 3 In the example, message 312 is NB-specific. On the other hand, because RAN-CP 404 performs UE-CP functions for some UEs, UE-specific message 416 originates from RAN-CP 404 (rather than...). Figure 3 (DU-1 in the example). Because the UE-specific message 416 is addressed to the UE associated with the neighboring NB 406, the UE-specific message 416 is sent to the neighboring NB 406.

[0121] exist Figure 4 In the example, the neighboring NB 406 sends a UE-specific message 418 to RAN-CP 404. The header of the UE-specific message 418 includes a UE-ID or another indicator (such as a service ID or cell ID) indicating where the UE-CP function for the relevant UE is located. Based on this header, RAN-CP 404 determines that the UE-specific message 418 can be processed locally in RAN-CP 404 in step 420 because the UE-CP function for the relevant UE is handled by RAN-CP 404.

[0122] Figure 4RAN-CP 404 also sends a cell-specific message 422 to DU-1 402. The header of cell-specific message 422 can identify the DU associated with the relevant cell (DU-1 in this case). Therefore, DU-1 402 processes cell-specific message 422 in step 424. Next, RAN-CP 404 receives UE-specific message 426 from neighboring NB 406. The header of UE-specific message 426 includes a UE-ID or another indicator (such as service ID or cell ID) indicating where the UE-CP function for the relevant UE is located. Based on this header, in step 428, RAN-CP 404 determines that UE-specific message 426 should be forwarded to DU-2 408 because the UE-CP function for the relevant UE is performed by DU-2. Therefore, at step 430, the forwarded message is sent from RAN-CP 404 to DU-2 408 to forward UE-specific message 426.

[0123] exist Figure 2-4 In the example, intermediate nodes can determine the next node to which a message will be forwarded. The determination of the next node is based on a header that may contain a CGI or NB-ID, AMF-ID, or RAN-UP-ID (User Plane ID) to identify the DU and RAN-CP, respectively. Various routing methods can be employed in embodiments of this disclosure, but typically such methods may include a routing table maintained by a central entity such as OAM.

[0124] Figure 5 and Figure 6 Two embodiments of initial access according to embodiments of this disclosure are shown. Figure 5 In the example, the UE-CP function is executed in the DU. Figure 5 In the initial access example, at step 512, UE 502 sends an RRC setup request (e.g., RRCSetupRequest) to DU 504. Because DU 504 handles the UE-CP function in this example, DU 504 processes the RRC setup request in step 514 and responds with an RRC setup message 516.

[0125] To indicate the completion of RRC establishment, UE 502 sends an RRC establishment completion message 518 to DU 504. Then, as part of performing UE-CP functions, DU sends an initial UE NAS message 520 to RAN-CP 506. The header of the initial UE NAS message 520 indicates the AMF 510 as the destination of the message. Thus, at step 522, RAN-CP 506 forwards the initial UE NAS message 520 to AMF 510 by sending a forwarded message 524.

[0126] In step 526, AMF 510 processes the forwarded initial UE NAS message 524, and in step 528, sends the initial context establishment request back to RAN-CP 506. Since the UE-CP function for UE 502 is handled by DU 504, RAN-CP 506 forwards the initial context establishment request to DU 504 in step 530. As described above, the forwarding mechanism is based on the header information of the initial context establishment request, which identifies the UE, serving, or cell, allowing RAN-CP 506 to determine the location of the UE-CP function based on the header information.

[0127] Upon receiving an initial context establishment request, DU 504 processes the request in step 532 and sends a bearer context establishment request 534, which has a header indicating that RAN-UP 508 is the destination of the message. Based on this header, RAN-CP 506 receives the bearer context establishment request 534 and forwards it in step 536 by sending a forwarded message 538 to RAN-UP 508.

[0128] RAN-UP 508 receives the forwarded bearer context establishment request and processes it in step 540. Subsequently, RAN-UP 506 sends a bearer context establishment response 542 to RAN-CP 506. Based on the header information of the bearer context establishment response 542, which indicates the location of the UE-CP for the UE, RAN-CP 506 determines that the UE-CP for the UE is located in DU 504 and forwards the bearer context establishment response to DU 504 in a forwarded message 544. In step 546, DU 504 processes the bearer context establishment response by performing UE context establishment.

[0129] Figure 6 An example of initial access for performing UE-CP functions of a UE in the CU / RAN-CP is shown. (Compared to...) Figure 5 compared to, Figure 6 The initial access message transmission has the same structure as UE 602, the difference being that RAN-CP 606 handles the UE-CP function of UE 602. As mentioned above, in Figure 5 In the example, the UE-CP function is handled by DU 504, and accordingly, the forwarding / processing in DU and RAN-CP is determined in Figure 5 and Figure 6 They are different.

[0130] Figure 5 and Figure 6The combination is intended to illustrate the flexible nature of interface message transmission of embodiments of the present disclosure by using header information as described in this disclosure, allowing network nodes to make appropriate forwarding / processing determinations to accommodate the flexible placement of UE-CP functions.

[0131] For example, from DU 604 Figure 6 The RRC establishment request received by UE 602 is forwarded by DU 604 to RAN-CP606 because... Figure 6 In the example, the UE-CP function of UE 602 is handled by RAN-CP 606, which is consistent with... Figure 5 The examples are different. Similarly, the initial UE NAS message and bearer context establishment request are both handled by RAN-CP 606 instead of... Figure 5 The DU is generated and sent to AMF 610 and RAN-UP 608 respectively.

[0132] Next, Figure 7 and Figure 8 Two variations of intra-node B handover according to embodiments of the present disclosure are shown. Intra-node B handover involves a handover from a source DU to a target DU within the same node B. Figure 7 In the middle, the UE-CP function is processed at the source DU and the target DU, while Figure 8 In the example, the UE-CP function is handled by the RAN-CP / CU. For example, in... Figures 3-6 In the example, Figure 7 and Figure 8 Messages sent between network entities have header content consistent with Table 1 above, which allows each network entity to determine whether to process or forward each message. In some embodiments, the header content is generated by the source node of the message and then reused or copied in any subsequent forwarded versions of the message.

[0133] exist Figure 7 In the example, the UE-CP function of UE 702 is initially performed by source DU 704. Reference numeral 710 indicates that source DU 704 processes the UE-CP function of UE 702 before initiating a handover. Then, UE 702 sends a measurement report to source DU 704 at step 712, wherein the measurement report includes channel, location, or other information indicating to DU 704 that a handover should be performed to target DU 708.

[0134] At step 714, source DU 704 makes a handover decision and sends a UE context establishment request 716 to RAN-CP (or CU) 706 to initiate the handover. Upon receiving the UE context establishment request 716, RAN-CP 706 determines at step 718 that it will not process the UE-CP function for UE 702 after the handover. Therefore, RAN-CP 706 forwards the UE context establishment request to target DU 708 in forwarded message 720, and target DU 708 will process the UE-CP function for UE 702 after the handover.

[0135] The UE context establishment request 716 includes header information according to embodiments of this disclosure, such as the format described above with respect to Table 1. In other words, the header information of the UE context establishment request 716 indicates the target CGI and UEID of the handover target, or other information that enables the RAN-CP 706 to determine which entity is performing or will be performing the UE-CP functions involved in the handover for the UE. For example, other information besides the UE ID could be a service ID or a cell ID.

[0136] Using the header information, RAN-CP 706 determines in step 718 that the target DU 708 will perform the UE-CP functions involved in the handover after the handover. When RAN-CP 706 forwards the UE context establishment request in forwarded message 720, the header information is copied from the UE context establishment request 716 to the forwarded message 720. In step 722, target DU 708 establishes the UE-CP functions for UE 702 in preparation for handover.

[0137] Next, target DU 708 sends a UE context establishment response 724 to RAN-CP 706. In step 726, RAN-CP 706 determines that DU 704 is currently performing a UE-CP function for UE 702. Therefore, RAN-CP 706 forwards the UE context establishment response to DU 704 in a forwarded message 728. As in step 718, the determination in step 726 is performed by RAN-CP based on the header information in the UE context establishment response 724, which provides sufficient information for RAN-CP 706 to determine which entity is performing a UE-CP function for the relevant UE. RAN-CP 706 may use additional resources (such as lookup tables or previously stored information) to determine the location of the UE-CP function based on the header of the received message.

[0138] Figure 8 This shows the handover within node B between DUs, and... Figure 7 Similar. However, in Figure 8In the example, the UE-CP function of the UE is performed in the RAN-CP / CU instead of the DU. The difference in the location of the UE-CP function leads to different processing / forwarding determinations between network nodes. Initially, step 810 represents the UE-CP function of UE 802 performed by RAN-CP 806 before handover.

[0139] Then, UE 802 sends a measurement report to DU 804, which forwards the report to RAN-CP 806, the entity handling UE-CP functions for UE 802. RAN-CP 806 makes a handover decision in step 812, at least in part, based on the forwarded measurement report. Therefore, RAN-CP 806 sends a UE context establishment request to target DU 808. In step 814, target DU 808 processes the UE context establishment request and sends a UE context establishment response to the RAN-CP. However, in Figure 8 In the example, target DU 808 will not process the UE-CP function for UE 802 after handover, because the UE-CP function will continue to be performed in RAN-CP 806.

[0140] As in Figure 7 In the example, network entities such as DU 804, target DU 808, and RAN-CP 806 are configured to determine whether to process or forward handover-related messages based on which entity performs the UE-CP function for UE 802. The network entities can determine which entity performs the UE-CP function for UE 802 based at least in part on header information in the handover-related message, which indicates the message's destination and other information indicating the flexible placement of the UE-CP function for the UE, such as the UE ID, service ID, or cell ID.

[0141] Figure 9 and Figure 10 Two examples of handover between nodes B are shown, where the handover is between source node B and target node B. For example, in Figure 7 and Figure 8 The example illustrates the flexible placement of UE-CP functionality and the different processing / forwarding behaviors of network nodes. Figure 9 In the example, the UE-CP function of the UE is executed in the DU of the source node B and the target node B before and after the handover.

[0142] Because Figure 9In the example, DU 906 of source node B 902 performs the UE-CP function for the UE, so DU 906 generates a handover request and sends it to RAN-CP 910 of source node B 902. In step 918, RAN-CP 910 determines to forward the handover request to RAN-CP 916 of target node B 904, because RAN-CP 910 does not handle the UE-CP function for the UE in this example.

[0143] The forwarded handover request is received by RAN-CP 916 of target Node B 904 and subsequently forwarded to DU 912 of target Node B 904, because RAN-CP 916 determines at step 920 that the UE-CP function for the UE will be performed by DU 912 of target Node B 904 after the handover. After the handover request is forwarded to and received by DU 912, the bearer context establishment procedure can be performed between DU 912 and RAN-CP 916 of target Node B 904.

[0144] Upon completion of the bearer context establishment process, DU 912 may send a handover request confirmation to RAN-CP 916, which forwards the handover request confirmation to RAN-CP 910, which in turn forwards it to DU 906. These forwarding operations are implemented by the header structure described in the embodiments of this disclosure, which allows each recipient of a UE-specific message to determine which entity handles the UE-CP function for the UE and, accordingly, whether and where to forward the UE-specific message.

[0145] exist Figure 9 In the example, upon receiving the forwarded handover request acknowledgment, DU 906 of source node B 902 participates in the bearer context modification process as part of the handover. Next, DU 906 sends a status message to RAN-CP910, which then forwards it to RAN-CP916, and then again to DU 912. This is as described above with reference to the handover request and handover request acknowledgment. Figure 9 Examples include forwarding UE-specific messages (in this case, handover-related messages) from the RAN-CP of each Node B to the corresponding DU of the Node B that handles the UE-CP function for the UE.

[0146] After receiving a state transition in DU 912, a bearer context modification can be performed between DU 912 and RAN-CP 916, and in step 922, the UE can connect to DU 912 via a random access channel. Subsequently, a handover success message is sent by DU 912 and forwarded first by RAN-CP 916, and then by RAN-CP 910 to DU 906.

[0147] Figure 10 It shows something similar to Figure 9 The inter-node B handover process, except that the UE-CP function of the UE is executed in the RAN-CP / CU of the source node B entity and the target node B entity, means that the RAN-CP 1010 of the source node B 1002 initiates the handover by sending a handover request to the RAN-CP 1016 of the target node B 1004. At step 1018, RAN-CP 1016 determines that the UE-CP function for the UE is executed locally in RAN-CP 1016, therefore the bearer establishment process is performed by RAN-CP 1016.

[0148] After bearer establishment, a UE context establishment procedure is performed between RAN-CP 1016 and DU 1012 of target node B 1004, and a handover request confirmation is sent from RAN-CP 1016 to RAN-CP 1010 of source node B 1002. Because... Figure 10 In the example, the UE-CP function is executed in the corresponding RAN-CP nodes of the source node B and the target node B, so it is not necessary to forward messages from the RAN-CP node to the DU node, as shown below. Figure 9 The example shows a scenario where the UE-CP function is performed in the DU node.

[0149] After RAN-CP 1010 receives the handover request confirmation, a UE context modification procedure is performed between RAN-CP 1010 and DU1006 at source node B 1002, and as part of the handover, bearer modification is performed by RAN-CP 1010. Subsequently, a state transition from RAN-CP 1010 to RAN-CP 1016 and the corresponding bearer modification procedure in RAN-CP 1016 are executed.

[0150] Next, the UE connects to the target node B 1004 via a random access channel, and RAN-CP 1016 sends a handover success message to RAN-CP 1010 of the source node B 1002. Figure 9 and Figure 10As shown, the messaging framework described in the embodiments of this disclosure can support inter-Node B handover, regardless of whether the UE-CP function is performed in the RAN-CP / CU or DU of the Node B entity. The handover and other communication scenarios described herein are merely examples, and the disclosed messaging framework can support any UE-related signaling.

[0151] For example, a state transition from inactive to connected for a UE may include paging performed by the DU of the Node B entity and controlled by the CU. This paging is also supported by a messaging framework according to embodiments of this disclosure, even though the UE-CP function is flexibly positioned and the UE context is flexibly stored. Figure 11 The diagram illustrates the transition of a UE from an inactive (e.g., RRC_INACTIVE) mode to a connected (e.g., RRC_CONNECTED) mode as data arrives at the RAN-UP.

[0152] Since the last known location of the UE and its information is in the previous DU that the UE connected to before changing to inactive mode, the process begins at that DU. That is, an arrival notification from the RAN-CP is forwarded to the DU where the UE last communicated, indicating that the UE has arrived and will page the UE. The last known DU pagees the UE, and if no response is received, the last known DU requests the RAN-CP to initiate paging.

[0153] Subsequently, the RAN-CP manages the process of finding a network node capable of paging the UE. If a new DU capable of paging the UE is found, the system determines the previous DU that last served the UE before the inactive mode in order to retrieve the UE context information from that previous DU. According to embodiments of this disclosure, several methods can be used to locate the UE context information, including an I-RNTI indicating the location of the UE context information or such a location stored in the RAN-CP.

[0154] Figure 11 and Figure 12 This illustrates a method for retrieving UE context information from the previous DU that last served the UE before the UE transitions to inactive mode. Figure 11 In the example, the UE-CP function for the UE is executed in the DU, and... Figure 12 In the example, the UE-CP function for the UE is executed in the RAN-CP. Figure 11 and Figure 12 In the example, I-RNTI is used to locate the UE context information.

[0155] Before UE 1102 enters inactive mode, an RRC message 1114 is sent from the DU serving UE 1102 (i.e., the old DU 1104). This RRC message includes an I-RNITI indicating whether the old DU 1104 stores UE context information. UE 1102 then enters inactive mode and, at a future point in time, detects service in RAN-UP 1106 at step 1116. Although Figure 11 It can be shown that RRC message 1114 and service detection 1116 occur simultaneously, but RRC message 1114 can be sent before the UE switches to inactive mode, and service detection 1116 can occur at some point after the UE switches to inactive mode.

[0156] In response to service detection 1116, data notification 1118 is sent from RAN-UP 1106 to RAN-CP 1108 to indicate that service detection for UE 1102 has occurred. Because RAN-CP 1108 stores information about which DU previously served UE 1102 before the inactive mode, RAN-CP 1108 sends data notification 1120 to the old DU 1104. Upon receiving data notification 1120, the old DU 1104 attempts to page UE 1102.

[0157] One of two things happens in response to a paging request from the old DU 1104: UE 1102 responds to the paging request because UE 1102 is still within the area of ​​the old DU 1104; or UE 1102 does not respond because UE 1102 has been relocated to the area of ​​another DU while in inactive mode. The events within the dashed rectangle 1124 correspond to the case where the UE is still within the area of ​​the old DU 1104 and responds to the paging request.

[0158] In case 1124, UE 1102 responds to paging 1122 by sending I-RNTI 1126 back to the old DU 1104, where the I-RNTI instructs the old DU 1104 to store UE context information of UE 1102. Therefore, upon receiving the I-RNTI, the old DU 1104 performs UE context establishment 1128 based on the UE context information stored therein, and an RRC message 1130 associated with resuming communication between UE 1102 and the old DU 1104 is exchanged.

[0159] Finally, at step 1132, a bearer establishment or recovery procedure is performed between the old DU 1104 and RAN-UP 1106 to support the transition of UE 1102 from inactive mode back to connected mode. However, if UE 1102 has not yet responded to paging 1122, none of the events in dashed rectangle 1124 will occur, and the system will infer that UE 1102 is no longer within range of the old DU 1104. Therefore, in response to the lack of a response to paging 1122, paging requests 1134 can be sent from the old DU 1104 and RAN-CP 1108 to other DUs 1110 and 1112 to page UE 1102.

[0160] Then, the other DUs 1110 and 1112 continue to transmit paging signals 1136 within their respective ranges to locate UE 1102. The event indicated in dashed rectangle 1137 occurs when UE 1102 responds to the paging signal from DU 1110. Initially, UE 1102 responds to the paging from DU 1110 by sending an RRC recovery request 1138. In some embodiments, the RRC recovery request 1138 may include an I-RNTI indicating that UE context information is stored in the legacy DU 1104.

[0161] In other embodiments, if the location of the UE context information is not available from the I-RNTI, the UE-CP location request / response signaling 1140 may be exchanged between DU 1110 and RAN-CP 1108, wherein the UE-CP location (and UE context information location) of UE 1102 is stored in RAN-CP 1108 and provided to DU 1110 upon request.

[0162] via I-RNTI or via UE-CP location request / response signaling 1140, DU 1110 determines that the UE context information for UE 1102 is stored in the legacy DU 1104. DU 1110 then sends a UE context retrieval request 1142 to the legacy DU 1104 and receives the UE context information in a UE context retrieval response 1144 in response. With the UE context information, DU 1110 is able to perform UE context establishment 1146.

[0163] Figure 12 It shows something similar to Figure 11 The RRC procedure is used to transfer the UE from inactive mode to connected mode, except... Figure 12 The UE-CP function of the UE is flexibly placed in the RAN-CP instead of the DU. Figure 11 and Figure 12The differences demonstrate the ability of the disclosed messaging framework to support, for example, the flexible placement of UE-CP functions in DU or RAN-CP.

[0164] exist Figure 12 In this process, RRC message 1214 is sent from RAN-CP 1208 to UE 1202 to put UE 1202 into inactive mode. RRC message 1214 may include an I-RNTI indicating UE context information (and UE-CP functionality) in RAN-CP 1208 for UE 1202. Sometime after UE 1202 transitions to inactive mode, service can be detected in RAN-UP 1206, and RAN-UP 1206 can send a data notification to RAN-CP 1208.

[0165] In response to a data notification, RAN-CP 1208 can send a paging request to the old DU 1204 to check if UE 1202 still has the old DU 1204. Dashed rectangle 1216 depicts the events that occur when UE 1202 responds to a paging request from the old DU 1204. In this case, UE 1202 responds to the paging from the old DU 1204 by sending an RRC recovery request to both the old DU 1204 and RAN-CP 1208.

[0166] The RRC recovery request may include an I-RNTI provided to UE 1202 and stored therein before transitioning to inactive mode. The legacy DU 1204 can perform UE context establishment 1218 based on its previous connection with UE 1202, and can exchange RRC recovery message passing between UE 1202 and RAN-CP 1208, with RAN-CP 1208 performing UE-CP functions for UE 1202. The bearer establishment or recovery procedure can then be performed by RAN-CP 1208 and RAN-UP 1206.

[0167] However, as in Figure 11 In the example, if UE 1202 does not respond to a paging request from the old DU 1204, a paging request can be sent from the old DU 1204 and RAN-CP 1208 to other DUs 1210 and 1212 within Node B. Based on the paging request, the other DUs 1210 and 1212 send paging messages to determine whether UE 1202 is within one of their respective ranges.

[0168] If UE 1202 responds to a paging from DU 1210, indicating that UE 1202 is within range of DU 1210, the event shown in dashed rectangle 1220 occurs. In this case, an RRC recovery request is sent to DU 1210, which forwards the request to RAN-CP 1208. Based on the UE-CP function in RAN-CP 1208 and the RRC recovery / transfer request, the new serving DU 1210, RAN-CP 1208, and RAN-UP 1206 can perform UE context and bearer establishment.

[0169] Figure 13 An example of a device 1300 configured to practice one or more example embodiments is shown. Device 1300 may include a UE (such as UE 502, 602, 702, 802, 1102 or 1202) or a network device (such as a DU or RAN-CP element described herein), or any device generally configured to implement the functions described herein.

[0170] The device 1300 may include at least one processor 1302. The at least one processor 1302 may include one or more of various processing devices, such as a coprocessor, microprocessor, controller, digital signal processor (DSP), processing circuitry 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.

[0171] The device 1300 may also include at least one memory 1304. The memory 1304 may be configured to store, for example, computer program code 1306, such as operating system software and application software. The memory 1304 may include one or more volatile memory devices, one or more non-volatile memory devices, and / or combinations thereof. For example, the memory 1304 may be embodied 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.).

[0172] Device 1300 may also include one or more communication interfaces 1308 configured to enable device 1300 to send and / or receive information to / from other devices. The communication interface may be configured to provide at least one radio connection, such as a 3GPP mobile broadband connection (e.g., 3G, 4G, 5G, or higher). However, communication interface 1308 may be configured to provide one or more other types of connections, such as a wireless local area network (WLAN) connection, for example, standardized by the IEEE 802.11 series or the Wi-Fi Alliance; a short-range wireless network connection, such as Bluetooth, NFC (Near Field Communication), or RFID connection; a wired connection, such as a local area network (LAN) connection, a Universal Serial Bus (USB) connection, or an optical network connection; or a wired internet connection. Communication interface 1308 may include or be configured to be coupled to at least one antenna to transmit and / or receive radio frequency signals. One or more of the various types of connections may also be implemented as a separate communication interface, which may be coupled to or configured to be coupled to multiple antennas.

[0173] The device 1300 may also include a user interface 1310, which includes input devices and / or output devices. Input devices may take various forms, such as a keyboard, a touchscreen, or one or more embedded control buttons. Output devices may include, for example, a display, a speaker, a vibration motor, etc.

[0174] When device 1300 is configured to perform certain functions, one or more components of device 1300 (e.g., at least one processor 1302 and / or memory 1304) may be configured to perform those functions. Furthermore, when at least one processor 1302 is configured to perform certain functions, those functions may be implemented using, for example, program code 1306 included in memory 1304.

[0175] 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 embodiment, device 1300 includes a processor or processor circuitry, such as a microcontroller, which, when executed, is configured by program code to perform embodiments of the described operations and functions. Alternatively or additionally, the functions described herein can be performed, at least in part, by one or more hardware logic components. Examples, but not limited to, illustrative types of hardware logic components that can be used include field-programmable gate arrays (FPGAs), application-specific integrated circuits (ASICs), application-specific standard products (ASSPs), systems-on-a-chip (SoCs), complex programmable logic devices (CPLDs), and graphics processing units (GPUs).

[0176] The apparatus 1300 includes components for performing at least one method described herein. In one example, the components include at least one processor 1302 and at least one memory 1304 including program code 1306 configured to cause the apparatus 1300 to perform the method when executed by the at least one processor 1302.

[0177] Device 1300 may include, for example, computing devices such as base stations, network nodes, server devices, client nodes, mobile phones, tablet computers, laptop computers, etc. In one example, device 1300 may include a vehicle, such as a car. Although device 1300 is shown as a single device, it should be understood that, where applicable, the functionality of device 1300 may be distributed across multiple devices.

[0178] Figure 14 An example of a message interface method in a communication network according to an example embodiment is shown. Method 1400 can be performed by a network node of the communication network or by a device configured to control its function when installed therein.

[0179] At operation 1402, the method may include: receiving a message from a network node on a radio access network (RAN) interface, wherein the message includes a routing header. At operation 1404, the method may include: determining, based on the routing header of the message, whether the means should process the message or forward the message to another network node. At operation 1406, the method may include: processing the message or forwarding the message to another network node based on the determination.

[0180] Figure 15 A second example of a message interface method in a communication network according to an example embodiment is shown. Method 1500 can be performed by a network node (such as a DU) of the communication network or by a device configured to control its function when installed therein.

[0181] At operation 1502, the method may include: receiving a message from a user equipment (UE) on a radio access network (RAN) interface. At operation 1504, the method may include: determining, based on whether the device is configured to perform UE control plane (UE-CP) functions for the UE, whether the device should process the message or forward it to a network node, wherein the device is associated with a network node and configured to handle radio resource control (RRC) for the UE. At operation 1506, the method may include: processing the message or forwarding the message to a network node based on the determination.

[0182] Figure 16A third example of a messaging interface method in a communication network according to an example embodiment is shown. Method 1600 can be performed by a user equipment (UE) or by a means configured to control its function when installed therein.

[0183] At operation 1602, the method may include: receiving a radio resource control (RRC) message from a first network node, the RRC message including an indication of whether the first network node is configured to perform UE control plane (UE-CP) functions for a UE device, or whether a second network node different from the first network node is configured to perform UE-CP functions for a UE device.

[0184] At operation 1604, the method may include: based on the UE device switching from an inactive mode to a connected mode, sending a message including an indication of whether a first network node is configured to perform a UE-CP function for the UE device, or whether a second network node is configured to perform a UE-CP function for the UE device.

[0185] At operation 1606, the method may include: communicating with a third network node in a connection mode, the third network node having acquired UE context information for the UE device based on a sent instruction, wherein the third network node is a first network node or another network node.

[0186] Other features of the method are directly derived from the functions and parameters of the apparatus as described in the appended claims and throughout the specification, and therefore will not be repeated here. Note that one or more operations of the method may be performed in different orders.

[0187] Apparatus (e.g., network node, base station, TRP, user node, or client node) may be configured to perform or cause the performance of any aspect of the methods described herein. Furthermore, a computer program may include instructions for causing the apparatus to perform any aspect of the methods described herein when executed. Additionally, the apparatus may include components for performing any aspect of the methods described herein. According to an example embodiment, the components include at least one processor and a memory including program code configured to cause the performance of any aspect of the methods when executed by the at least one processor.

[0188] As stated above, an advantage of the disclosed communication framework is the service-agnostic nature of its message exchange mechanism, which allows services such as UE-CP to be flexibly placed in logical / network nodes. Figure 4-12 As shown, the UE-CP function can be flexibly placed in the DU or RAN-CP (or CU), and the communication framework supports this flexible placement.

[0189] Furthermore, due to the service-agnostic nature of the messages and their header structure, future changes to services or functions will not affect the effectiveness of the communication framework. Finally, due to the transparency of the messages and the ability to address / forward messages to the appropriate recipients by analyzing header information, the exposed communication framework will also support further service decomposition.

[0190] Furthermore, the various implementations of this disclosure can be described with reference to the following terms, and their features can be combined in any reasonable manner.

[0191] Clause 1. An apparatus comprising: at least one processor; and at least one memory including computer program code, the at least one memory and the computer program code being configured, together with the at least one processor, to cause the apparatus to at least: receive a message from a network node on a radio access network (RAN) interface, wherein the message includes a routing header; determine, based on the routing header of the message, whether the apparatus should process the message or forward the message to another network node; and process the message or forward the message to the other network node based on the determination.

[0192] Clause 2. The apparatus according to Clause 1, wherein the routing header includes an interface common field that identifies at least one of the following: user equipment (UE), service associated with the UE, cell for the UE, or public service.

[0193] Clause 3. The apparatus according to Clause 2, wherein the at least one memory and the computer program code are configured, together with the at least one processor, to cause the apparatus to: determine, based on at least one of the routing header or the interface common fields, whether to process the message or to forward the message to a second apparatus associated with the apparatus.

[0194] Clause 4. The apparatus according to Clause 3, wherein the message is a UE-specific message; one of the apparatus or the second apparatus performs a UE control plane (UE-CP) function for the UE by processing radio resource control (RRC) for the UE; and the at least one memory and the computer program code are configured, together with the at least one processor, for the apparatus to: determine, based on the interface common field, to forward the message to the second apparatus associated with the apparatus, based on the UE-CP function for the UE being performed by the second apparatus associated with the apparatus; or determine, based on the interface common field, to process the message by the apparatus, based on the interface common field, based on the UE-CP function for the UE being performed by the apparatus.

[0195] Clause 5. The apparatus according to Clause 4, wherein the at least one memory and the computer program code are configured together with the at least one processor to cause the apparatus to: in response to determining that the message is to be forwarded to a second device associated with the apparatus, select, based on the interface common field, a second device associated with the apparatus, the second device being configured to perform the UE-CP function for the UE.

[0196] Clause 6. The apparatus according to Clause 3, wherein the at least one memory and the computer program code are configured together with the at least one processor to enable the apparatus to: perform a UE control plane (UE-CP) function for all UEs in the cell associated with the apparatus, determining, based on the cell, to forward the message to the second device associated with the apparatus; or, based on the UE-CP function for all UEs in the cell associated with the apparatus being performed by the apparatus, determining, based on the cell, that the message be processed by the apparatus.

[0197] Clause 7. The apparatus according to Clause 3, wherein the at least one memory and the computer program code are configured together with the at least one processor to cause the apparatus to: process a UE context retrieval request by determining whether the UE context is stored in the apparatus or the second apparatus based on whether the UE control plane (UE-CP) function for the UE is performed by the second apparatus associated with the apparatus or by the apparatus itself.

[0198] Clause 8. The apparatus according to Clause 7, wherein the at least one memory and the computer program code are configured, together with the at least one processor, to cause the apparatus to: determine, based on a node local identifier included in the UE context retrieval request, whether the UE context is stored in the apparatus or in a second apparatus associated with the apparatus, the node local identifier indicating whether the UE-CP function for the UE is performed by the second apparatus or by the apparatus.

[0199] Clause 9. The apparatus according to Clause 7, wherein the at least one memory and the computer program code are configured together with the at least one processor to enable the apparatus to: determine, based on location information stored in the apparatus, whether the UE context is stored in the apparatus or in a second apparatus associated with the apparatus, the location information indicating whether the UE-CP function for the UE is performed by the second apparatus or by the apparatus.

[0200] Clause 10. The apparatus according to Clause 7, wherein the at least one memory and the computer program code are configured together with the at least one processor to cause the apparatus to: store location information in the apparatus indicating whether the UE-CP function for the UE is performed by the second apparatus or by the apparatus itself.

[0201] Clause 11. The apparatus according to Clause 4, wherein the routing header, together with the interface common field, includes a network node identifier or a functional module identifier, the network node identifier or the functional module identifier indicating the network node or functional module to process the UE-specific message.

[0202] Clause 12. The apparatus according to Clause 1, wherein the message is not a UE-specific message; and the routing header includes a network node identifier or a functional module identifier, the network node identifier or the functional module identifier indicating the network node or functional module to which the message is destined.

[0203] Clause 13. An apparatus comprising: at least one processor; and at least one memory including computer program code, the at least one memory and the computer program code being configured, together with the at least one processor, to cause the apparatus to at least: receive a message from a user equipment (UE) on a radio access network (RAN) interface; determine, based on whether the apparatus is configured to perform UE control plane (UE-CP) functions for the UE, whether the apparatus should process the message or forward the message to a network node, wherein the apparatus is associated with the network node and configured to process radio resource control (RRC) for the UE; and process the message or forward the message to the network node based on the determination.

[0204] Clause 14. The apparatus according to Clause 13, wherein the at least one memory and the computer program code are configured, together with the at least one processor, to cause the apparatus to: receive a second message from the network node on the RAN interface, wherein the second message is a UE-specific message and includes a routing header including an interface common field that identifies at least one of the following: the user equipment (UE), a service associated with the UE, or a cell associated with the UE; and process the UE-specific message according to the interface common field by performing the UE-CP function for the UE in the apparatus.

[0205] Clause 15. The apparatus according to Clause 13, wherein the at least one memory and the computer program code are configured, together with the at least one processor, to cause the apparatus to: receive a third message from the network node on the RAN interface, wherein the third message is not a UE-specific message and includes a network node identifier or a functional module identifier, the network node identifier or the functional module identifier indicating a network node or functional module as the destination of the message; and process the third message in the apparatus.

[0206] Clause 16. The apparatus according to Clause 14, wherein the routing header of the UE-specific message, together with the interface common field, includes a network node identifier or functional module identifier, the network node identifier or functional module identifier indicating the network node or functional module to which the UE-specific message is destined.

[0207] Clause 17. The apparatus according to Clause 13, wherein the at least one memory and the computer program code are configured, together with the at least one processor, to cause the apparatus to: determine whether to process the message or to forward the message to the network node, based on whether the apparatus is configured to perform UE-CP functionality for all UEs in a cell associated with the UE.

[0208] Clause 18. The apparatus according to Clause 14, wherein the at least one memory and the computer program code are configured together with the at least one processor to cause the apparatus to: in response to a UE context retrieval request, send UE context information to the network node, wherein the UE context information is sent together with the interface common field of the UE.

[0209] Clause 19. The apparatus according to Clause 13, wherein the at least one memory and the computer program code are configured together with the at least one processor to enable the apparatus to: perform the UE-CP function for the UE based on the apparatus, and store UE context information associated with the UE in the apparatus.

[0210] Clause 20. A user equipment (UE) apparatus comprising: at least one processor; and at least one memory including computer program code, the at least one memory and the computer program code being configured, together with the at least one processor, to cause the UE apparatus to at least: receive a radio resource control (RRC) message from a first network node, the RRC message including an indication of whether the first network node is configured to perform a UE control plane (UE-CP) function for the UE apparatus, or whether a second network node different from the first network node is configured to perform the UE-CP function for the UE apparatus; transmit a message including the indication of whether the first network node is configured to perform the UE-CP function for the UE apparatus, or whether the second network node is configured to perform the UE-CP function for the UE apparatus, based on the UE apparatus transitioning from an inactive mode to a connected mode; and communicate with a third network node in the connected mode, the third network node having acquired UE context information for the UE apparatus based on the transmitted indication, wherein the third network node is the first network node or the other network node.

Claims

1. A device for communication, comprising: At least one processor; as well as At least one memory, including computer program code, said at least one memory and said computer program code being configured together with said at least one processor to cause the device to at least: Receive messages from network nodes on the radio access network (RAN) interface, wherein the messages include routing headers; Based on the routing header of the message, the device determines whether to process the message or forward it to another network node; as well as The message is processed or forwarded to the other network node based on the determination.

2. The apparatus according to claim 1, wherein The routing header includes an interface common field that identifies at least one of the following: user equipment (UE), service associated with the UE, cell for the UE, or public service.

3. The apparatus of claim 2, wherein the at least one memory and the computer program code are configured to, together with the at least one processor, enable the apparatus to: Based on at least one of the routing header or the interface common fields, it is determined whether to process the message or to forward the message to a second device associated with the device.

4. The apparatus according to claim 3, wherein The message is a UE-specific message; One of the devices, or the second device, performs UE control plane (UE-CP) functions for the UE by processing radio resource control (RRC) for the UE; and The at least one memory and the computer program code are configured to, together with the at least one processor, enable the device to: Based on the fact that the UE-CP function for the UE is performed by the second device associated with the device, the method for determining whether to forward the message to the second device associated with the device is based on the interface common fields; or Based on the UE-CP function for the UE being executed by the device, the message to be processed by the device is determined according to the interface common fields.

5. The apparatus of claim 4, wherein the at least one memory and the computer program code are configured to, together with the at least one processor, enable the apparatus to: In response to determining that the message should be forwarded to the second device associated with the device, the second device associated with the device is selected from a plurality of devices associated with the device based on the interface common field, the second device being configured to perform the UE-CP function for the UE.

6. The apparatus of claim 3, wherein the at least one memory and the computer program code are configured to, together with the at least one processor, enable the apparatus to: Based on the fact that the second device associated with the device is configured to perform UE control plane (UE-CP) functions for all UEs in the cell of the device, the system determines, according to the cell, whether to forward the message to the second device associated with the device; or The UE-CP function for all UEs in the cell of the device is performed by the device, and the message is determined to be processed by the device based on the cell.

7. The apparatus of claim 3, wherein the at least one memory and the computer program code are configured to, together with the at least one processor, enable the apparatus to: The UE context retrieval request is processed by determining whether the UE context is stored in the device or the second device based on whether the UE control plane (UE-CP) function for the UE is performed by the second device associated with the device or by the device itself.

8. The apparatus of claim 7, wherein the at least one memory and the computer program code are configured to, together with the at least one processor, enable the apparatus to: Based on the node local identifier included in the UE context retrieval request, it is determined whether the UE context is stored in the device or in the second device associated with the device, the node local identifier indicating whether the UE-CP function for the UE is performed by the second device or by the device.

9. The apparatus of claim 7, wherein the at least one memory and the computer program code are configured to, together with the at least one processor, enable the apparatus to: Based on location information stored in the device, it is determined whether the UE context is stored in the device or in a second device associated with the device, the location information indicating whether the UE-CP function for the UE is performed by the second device or by the device.

10. The apparatus of claim 7, wherein the at least one memory and the computer program code are configured to, together with the at least one processor, enable the apparatus to: The device stores location information indicating whether the UE-CP function for the UE is performed by the second device or by the device itself.

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