Communication method and related product

Abstract

The present application discloses a communication method and a related product. The method comprises: a first DU acquires first information from a first network element, and an RLF report, wherein the first information is used for determining a cause of a layer 1 or layer 2 triggered mobility (LTM) connection failure, and is specifically, for example, a time threshold or indication information for the cause of the LTM connection failure; and the first DU determines the cause of the LTM connection failure on the basis of the first information. By using the method of embodiments of the present application, analysis of an LTM connection failure and problem detection can be implemented, and a DU in a network device can fully participate in the process, thereby reducing the probability of the LTM connection failure.

Description

Communication method and related products

[0001] The present application claims priority to the Chinese patent application No. 202411098006.7, filed on August 9, 2024, and entitled "Communication method and related products", the content of which is incorporated herein by reference in its entirety. TECHNICAL FIELD

[0002] The present application relates to the field of communication technology, in particular to a communication method and related products. BACKGROUND

[0003] Layer 3 (L3) handover includes basic handover, conditional handover (CHO) and dual active protocol stack (DAPS) and the like. In L3 handover, the change of serving cell is triggered by L3 measurement and is completed based on radio resource control (RRC) signaling (including RRC reconfiguration message with synchronization information element). In L3 handover, high layer reconfiguration (i.e. RRC / packet data convergence protocol (PDCP) layer) and / or reset of underlying layer (e.g. medium access control (MAC) layer (may be referred to as layer 2 (L2)), physical layer (may be referred to as layer 1 (L1)) are required. Therefore, L3 handover will cause longer latency, larger signaling overhead and longer interruption latency.

[0004] L1 / L2 triggered mobility (LTM) is introduced later to reduce mobility latency. In the current LTM procedure, the centralized unit (CU) in the network device decides to initiate the LTM configuration procedure, prepares candidate cell configuration, and completes the RRC reconfiguration process of the user equipment (UE). Then the distributed unit (DU) in the network device decides to perform LTM handover to the target cell according to the L1 measurement result sent by the UE.

[0005] The existing mobility robustness optimization (MRO) mechanism does not consider how to implement the LTM connection failure determination process. SUMMARY

[0006] The embodiment of the present application provides a communication method and related products, which can realize LTM connection failure analysis and problem detection, and make the DU in the network equipment fully participate in the process, thereby reducing the probability of LTM connection failure.

[0007] In a first aspect, the present application provides a communication method. The method comprises: a first distributed unit (DU) receiving a radio link failure (RLF) report from a first CU; the first DU receiving first information from a first network element, the first information being used to determine a cause of layer 1 or layer 2 triggered mobility (LTM) connection failure; and the first DU performing cause analysis of the LTM connection failure.

[0008] The first aspect solution can be executed by a network equipment or a module (such as a chip system) in the network equipment, and can also be executed by a logic node, a logic module or software capable of realizing all or part of the network equipment functions, and no limitation is made in this regard.

[0009] In the embodiment of the present application, the first information is received by the DU, and the cause of the LTM connection failure is determined according to the first information. The DU can accurately and efficiently perform LTM connection failure analysis, problem detection and possible mobility parameter optimization according to the known cause of the LTM connection failure, thereby reducing the probability of LTM connection failure and improving the accuracy of LTM handover decision.

[0010] In a feasible implementation, the first information is a first time threshold; or the first information is indication information of the cause of the LTM connection failure; or the first information is a cell radio network temporary identifier (C-RNTI) used by a terminal device in the first DU or a source cell.

[0011] In a feasible implementation, when the first information is a first time threshold, the first network element is a first centralized unit (CU) or an operation administration and maintenance (OAM) entity.

[0012] In the embodiment of the present application, the DU receives the first time threshold from the OAM entity or the first CU, and determines the cause of the LTM connection failure. The DU can efficiently perform LTM connection failure analysis, problem detection and possible mobility parameter optimization according to the known cause of the LTM connection failure, thereby reducing the probability of LTM connection failure and improving the accuracy of LTM handover decision. In addition, obtaining the first time threshold from the OAM entity can reduce the number of interactions between network elements or entities. Obtaining the first time threshold from the first CU avoids the interaction between the OAM and the DU.

[0013] In a feasible implementation, when the first information is indication information of the cause of the LTM connection failure, the first network element is the first CU.

[0014] In the embodiments of the present application, the DU receives the indication information of the cause of the LTM connection failure from the first CU, so that the DU can quickly and directly know the cause of the LTM connection failure, so that the DU can efficiently perform LTM connection failure analysis, problem detection and possible mobility parameter optimization, reduce the probability of LTM connection failure, and improve the accuracy of LTM handover decision. In addition, the CU determines the cause of the LTM connection failure and indicates it to the DU, which can more accurately identify the DU that needs to send an RLF report, reduce the analysis / detection process of the DU for the cause of the LTM connection failure, and reduce the energy consumption of the DU.

[0015] In a possible implementation, the first information is a cell radio network temporary identifier (C-RNTI) used by the terminal device in the first DU or the source cell, the first network element is a first CU, and the first CU indicates the C-RNTI of the terminal device in the source cell to the first DU as the first information based on a mapping relationship between the C-RNTI used by the terminal device in the target cell in the RLF report and the C-RNTI of the target cell and the C-RNTI of the source cell stored by the first CU, where the source cell belongs to the first DU.

[0016] In the embodiments of the present application, the first DU identifies the terminal device that has ever connected to the source cell or the first DU before the connection failure occurs and the context related to the terminal device based on the cell radio network temporary identifier (C-RNTI) used by the terminal device in the first DU or the source cell, so that the DU can efficiently perform LTM connection failure analysis, problem detection and possible mobility parameter optimization, reduce the probability of LTM connection failure, and improve the accuracy of LTM handover decision.

[0017] In a possible implementation, the method further includes: performing root cause analysis of the LTM connection failure by the first DU.

[0018] In a possible implementation, the method further includes: if the first DU determines that the root cause of the LTM connection failure corresponds to another DU or CU, or the first DU determines that the root cause of the LTM connection failure is not in the first DU, the first DU sends second information to the first CU, where the second information indicates that the root cause of the LTM connection failure is in another DU or CU or not in the first DU, and the other DU is one or more DU(s) other than the first DU.

[0019] In a possible implementation, the second information further indicates the cause of the LTM connection failure.

[0020] In a possible implementation, the method further includes: if it is determined that the root cause of the LTM failure occurs in the first DU, the first DU performs mobility parameter optimization.

[0021] In the embodiments of the present application, the first DU determines the cause of the LTM connection failure according to the first information and the RLF report, and further analyzes to determine whether the root cause of the LTM connection failure occurs at the first DU. If yes, the first DU further performs mobility parameter optimization. If not, the first CU sends the second information to the first CU, so that the first CU forwards the RLF report to other DUs or the CU itself to analyze the root cause of the connection failure. The process of analyzing the root cause of the LTM connection failure by the first DU improves the efficiency and accuracy of problem analysis. Moreover, it helps to improve the effectiveness of further mobility parameter optimization by the DU.

[0022] In a possible implementation, the RLF report is carried in an RLF report container, and the first information is carried in information outside the RLF report container.

[0023] In a second aspect, the present application provides a communication method. The method comprises: a first CU sending an RLF report to a first DU; and the first CU sending first information to the first DU, the first information being used to determine the cause of the LTM connection failure.

[0024] The second aspect can be executed by a network device or a module (such as a chip system, etc.) in the network device, and can also be executed by a logic node, a logic module or software capable of realizing all or part of the functions of the network device, and the present application is not limited in this regard.

[0025] In a possible implementation, the first information is a first time threshold; or the first information is indication information of the cause of the LTM connection failure.

[0026] In a possible implementation, when the first information is the first time threshold, the method further comprises: the first CU obtaining the first time threshold configured by an operation maintenance management (OAM) entity.

[0027] In a possible implementation, when the first information is the indication information of the cause of the LTM connection failure, the method further comprises: the first CU obtaining a first time threshold configured by an OAM entity, and the first CU determining the cause of the LTM connection failure according to the first time threshold.

[0028] In a possible implementation, the method further comprises: the first CU receiving second information from the first DU, the second information indicating that the root cause of the LTM connection failure occurs at other DUs or a CU, or indicating that the root cause of the LTM connection failure does not occur at the first DU, the other DUs being one or more DUs other than the first DU.

[0029] In a possible implementation, the second information further indicates the type of the LTM connection failure.

[0030] In an implementation, the first CU sends the RLF report to the second DU after receiving the second information from the first DU, and the second DU is at least one of the other DUs.

[0031] In an implementation, the first CU sends the first information to the second DU.

[0032] In an implementation, the RLF report is carried in an RLF report container, and the first information is carried in information outside the RLF report container.

[0033] In a third aspect, a communication apparatus is provided, which comprises units or modules for performing the method in any of the first aspect or the second aspect.

[0034] In a fourth aspect, a communication apparatus is provided, which comprises at least one processor coupled with a memory, and the processor is configured to execute computer programs or instructions stored in the memory, so that the method in any of the first aspect or the second aspect is performed.

[0035] In a fifth aspect, a communication system is provided, which comprises a first apparatus and a second apparatus, wherein the first apparatus is configured to perform the method in any of the first aspect, and the second apparatus is configured to perform the method in any of the second aspect.

[0036] In a sixth aspect, a computer readable storage medium is provided, which stores computer instructions, and when the computer instructions are executed, the computer performs the method in any of the above aspects.

[0037] In a seventh aspect, a computer program product is provided, which comprises computer program codes, and when the computer program codes are executed by a computer, the computer performs the method in any of the above aspects.

[0038] In an eighth aspect, a chip is provided, which is coupled with a memory, and is configured to read and execute program instructions in the memory, so that the apparatus in which the chip is located performs the method in any of the above aspects. BRIEF DESCRIPTION OF DRAWINGS

[0039] The following describes the drawings used in the embodiments of the present application.

[0040] FIG. 1A is a wireless communication system architecture provided by an embodiment of the present application.

[0041] FIG. 1B is a schematic diagram of an NR protocol stack and network element modules of a RAN provided by an embodiment of the present application.

[0042] FIG. 1C is an O-RAN architecture diagram provided by an embodiment of the present application.

[0043] FIG. 1D is an LTM flowchart with a base station provided by an embodiment of the present application.

[0044] FIGS. 2-6C are flowcharts of communication methods provided by embodiments of the present application.

[0045] FIG. 7 is a structural schematic diagram of a communication device provided by an embodiment of the present application.

[0046] FIGS. 8 and 9 are structural schematic diagrams of a network device provided by embodiments of the present application.

[0047] FIG. 10 is a structural schematic diagram of a UE provided by an embodiment of the present application. DETAILED DESCRIPTION

[0048] The technical solutions in the embodiments of the present application will be described below with reference to the accompanying drawings in the embodiments of the present application. In the embodiments of the present application, the terms “system” and “network” can be used interchangeably. Unless otherwise specified, “ / ” represents an “or” relationship between the objects associated before and after it, for example, A / B can represent A or B; in the present application, “and / or” is only a description of the associated relationship between the associated objects, which means that there can be three relationships, for example, A and / or B, which can represent the following three cases: A exists alone, A and B exist together, and B exists alone, where A and B can be singular or plural. In addition, in the description of the present application, “multiple” means two or more than two, unless otherwise specified. “At least one of the following” or similar expressions means any combination of these items, including any combination of single item or multiple items. For example, at least one of a, b, or c can represent a, b, c, a-b, a-c, b-c, or a-b-c, where a, b, and c can be one or more. In addition, in order to clearly describe the technical solutions of the embodiments of the present application, in the embodiments of the present application, the same items or similar items with basically the same function are distinguished by using “first”, “second”, etc. The skilled in the art can understand that “first”, “second”, etc. do not limit the quantity and execution order, and “first”, “second”, etc. also do not necessarily mean different.

[0049] Reference within the specification to "one embodiment" or "an embodiment" or "some embodiments" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. The appearances of the phrase "in one embodiment" or "in some embodiments" in various places within specified

[0050] In addition, in the embodiments of the present application, the words "example" or "for example" are used to mean serving as an instance, illustration, or demonstration. Any embodiment or design presented as an example in the present application should not be construed as preferred or advantageous over other embodiments or designs. Rather, the word "example" is intended to present a concept in a particular way.

[0051] In the embodiments of the present application, "information", "signal", "message", "channel", and "signaling" can be used interchangeably, and it should be noted that when the distinction is not emphasized, the meanings are matched. "Of", "corresponding", and "corresponding" can be used interchangeably, and it should be noted that when the distinction is not emphasized, the meanings are matched. In addition, " / " mentioned in the present application can be used to represent the relationship of "or".

[0052] The following detailed description of the specific implementation of the present application further describes the objectives, technical solutions, and beneficial effects of the present application. It should be understood that the following is only a specific implementation of the present application and is not used to limit the protection scope of the present application. Any modification, equivalent replacement, improvement, etc. made on the basis of the technical solutions of the present application should be included in the protection scope of the present application.

[0053] In various embodiments of the present application, the terms and / or descriptions of different embodiments are consistent and can be mutually referred to if there is no special description and logical conflict. The technical features in different embodiments can be combined to form new embodiments according to their inherent logical relationship.

[0054] The system architecture related to the embodiments of the present application is introduced below.

[0055] Referring to FIG. 1A, FIG. 1A is a wireless communication system architecture provided by an embodiment of the present application. As shown in FIG. 1A, a wireless communication system 1000 includes a radio access network (RAN) 100 and a core network (CN) 200. The RAN 100 includes at least one RAN node (e.g., 110a and 110b in FIG. 1A, collectively referred to as 110) and at least one terminal (e.g., 120a-120j in FIG. 1A, collectively referred to as 120). The RAN can also include other RAN nodes, such as wireless relay devices and / or wireless backhaul devices (not shown in FIG. 1A), etc. The terminal 120 is connected to the RAN node 110 in a wireless manner. The RAN node 110 is connected to the core network 200 in a wireless or wired manner. The core network device in the core network 200 and the RAN node 110 in the RAN 100 can be different physical devices respectively, or can be the same physical device integrated with the logical functions of the core network and the radio access network.

[0056] The RAN 100 can be a 3rd generation partnership project (3GPP) related cellular system, such as a 4G, 5G mobile communication system, a satellite communication / non-terrestrial network (NTN) system, or a future-oriented evolution system. The RAN 100 can also be an open radio access network (O-RAN or ORAN), a cloud radio access network (CRAN), or a wireless fidelity (WiFi) system, and can also be a communication system combining two or more of the above systems.

[0057] The terminal involved in the embodiments of the present application can also be referred to as a terminal device, a user equipment (UE), and the like. The terminal device is an entity on the user side for receiving or transmitting signals, used for sending uplink signals to a network device or receiving downlink signals from the network device; the main functions include collecting data (part of the terminal device), receiving control information and downlink data of the network device, and transmitting electromagnetic waves to transmit uplink data to the network device. The terminal device can communicate with one or more core networks through the network device. The terminal device includes a handheld device with a wireless connection function, another processing device connected to a wireless modem, or a vehicle-mounted device, and the like. The terminal device can be a portable, pocket-sized, handheld, built-in computer, or vehicle-mounted mobile device. The terminal device can be widely used in various scenarios, such as cellular communication, D2D, V2X, point-to-point (P2P), machine-to-machine (M2M), machine type communication (MTC), internet of things (IoT), virtual reality (VR), augmented reality (AR), industrial control, autonomous driving, remote medical treatment, smart power grid, smart furniture, smart office, smart wear, smart transportation, smart city, unmanned aerial vehicle, robot, remote sensing, passive sensing, positioning, navigation, autonomous delivery, and mobile, and the like.Some examples of the terminal device are: a user equipment (UE) of a 3GPP standard, a fixed device, a mobile device, a handheld device, a wearable device, a cellular phone, a smart phone, a session initiated protocol (SIP) phone, a notebook, a personal computer, a smart book, a vehicle, a satellite, a global positioning system (GPS) device, a drone, a helicopter, an aircraft, a ship, a remote control device, a smart home device, an industrial device, a personal communication service (PCS) phone, a wireless local loop (WLL) station, a personal digital assistant (PDA), a wireless webcam, a tablet, a palm computer, a mobile internet device (MID), a wearable device such as a smart watch, a VR device, an AR device, a wireless terminal in industrial control, a terminal in Internet of Vehicles, a wireless terminal in self-driving, a wireless terminal in smart grid, a wireless terminal in transportation safety, a wireless terminal in smart city such as a smart fuel dispenser, a terminal device on a high-speed rail, and a wireless terminal in a smart home such as a smart speaker, a smart coffee machine, a smart printer, etc. The terminal device can be a wireless device in the above various scenarios or an apparatus used in a wireless device, for example, a communication module, a modem, or a chip in the above devices, etc. The terminal device can also be referred to as a terminal, a terminal device, a UE, a mobile station (MS), a mobile terminal (MT), etc. The terminal device can also be a terminal device in a future wireless communication system. The terminal device can be used in a dedicated network device or a general-purpose device. The embodiments of the present application do not limit the specific technology and specific device form of the terminal device.

[0058] In this application, the communication device for realizing the function of the terminal device can be a terminal device, a terminal device with part of the function of the terminal device, or a device capable of supporting the function of the terminal device, such as a chip system, which can be installed in the terminal device or matched with the terminal device. In this application, the chip system can be composed of a chip or include a chip and other discrete devices. In the technical solutions provided in this application, the communication device is taken as an example for description.

[0059] The wireless access network node involved in the embodiments of the present application is used to receive uplink signals from terminal devices or transmit downlink signals to terminal devices. The access network node can also be referred to as a base station (BS), a RAN device or network element, an access point (AP), a small tower, etc. The base station can be broadly covered by various names in the following or be replaced by the following names, such as: RAN node, Node B (NodeB), evolved Node B (eNB), next generation Node B (gNB), access network device in open radio access network (O-RAN), relay station, access point, transmitting and receiving point (TRP), transmitting point (TP), master eNB (MeNB), secondary eNB (SeNB), multi-standard radio (MSR) node, home base station, network controller, access node, wireless node, access point (AP), transmission node, transceiver node, building baseband unit (BBU), remote radio unit (RRU), active antenna unit (AAU), remote radio head (RRH), centralized unit (CU), distributed unit (DU), radio unit (RU), centralized unit control plane (CU-CP) node, centralized unit user plane (CU-UP) node, positioning node, etc. The base station can be a macro base station, a micro base station, a relay node, a donor node or the like, or a combination thereof. The network device can also refer to a communication module, modem or chip used in the aforementioned devices or apparatuses. The network device can also be a mobile switching center and a device-to-device (D2D), vehicle-to-everything (V2X), machine-to-machine (M2M) communication device that assumes the function of a base station, a network side device in a future communication system, etc. The network device can support networks of the same or different access technologies. The embodiments of the present application do not limit the specific technology and specific device form adopted by the network device.

[0060] Referring to FIG. 1B, FIG. 1B is a schematic diagram of an NR protocol stack and network element modules of a RAN according to an embodiment of the present application. As shown in FIG. 1B, the RAN device can include at least one CU and at least one DU. In some examples, the CU is a logical node that carries the radio resource control (RRC) layer, the service data adaptation protocol (SDAP) layer, the packet data convergence protocol (PDCP) layer, and other control functions of the access network device. The CU is connected to network nodes such as a core network through some interfaces, which can be E2 interfaces or the like. Optionally, the CU can have part of the functions of the core network. The CU (e.g., the PDCP layer and higher layers) is connected to the DU (e.g., the RLC layer and lower layers) through some interfaces, which can be F1 interfaces or the like. In some examples, these interfaces (e.g., the F1 interface) can provide control plane (C-Plane) and user plane (U-Plane) functions (e.g., interface management, system information management, UE context management, RRC message transmission, etc.). The F1AP is an application protocol of the F1 interface, which defines the signaling procedures of the F1 in some examples. The F1 interface supports the control plane F1-C and the user plane F1-U.

[0061] In some examples, the CU can be split into a CU-CP (control unit-control plane) and a CU-UP (control unit-user plane), where the CU-CP is a logical node carrying the RRC layer and the PDCP-C (control plane part of PDCP) layer, used to implement the control plane function of the CU. The CU-CP can interact with a network element in the core network used to implement the control plane function. The network element in the core network used to implement the control plane function can be an access and mobility function network element, such as an access and mobility management function (AMF) in a 5G system. The AMF network element is used to be responsible for mobility management in a mobile network, such as location updating of a terminal device, registration of the terminal device to a network, handover of the terminal device, and the like. The CU-UP is a logical node carrying the SDAP layer and the PDCP-U (user plane part of PDCP) layer, used to implement the user plane function of the CU. The CU-UP can interact with a network element in the core network used to implement the user plane function. The network element in the core network used to implement the user plane function, for example, a user plane function (UPF) in a 5G system, is used to be responsible for forwarding and receiving data in a terminal device. The above configuration of the CU and the DU is merely an example, and the CU and the DU can have functions according to needs. For example, the CU or the DU can be configured to have more protocol layer functions, or the CU or the DU can be configured to have partial processing functions of the protocol layer. For example, part of the functions of the RLC layer and the functions of the protocol layer above the RLC layer are arranged in the CU, and the remaining functions of the RLC layer and the functions of the protocol layer below the RLC layer are arranged in the DU. For another example, the functions of the CU or the DU can be divided according to the service type or other system requirements, for example, according to the delay. The functions that need to meet the delay requirement are arranged in the DU, and the functions that do not need to meet the delay requirement are arranged in the CU.

[0062] The above-mentioned O-RAN aims to realize an intelligent and open access network. The main feature of the O-RAN architecture is the separation of software and hardware, which realizes the virtualization of network functions and the standardization of hardware. In addition, the O-RAN also introduces artificial intelligence (AI). Referring to FIG. 1C, which is an O-RAN architecture diagram provided by an embodiment of the present application, as shown in FIG. 1C, in the ORAN system, the CU can also be referred to as O-CU (open CU), the DU can also be referred to as O-DU, the CU-CP can also be referred to as O-CU-CP, the CU-UP can also be referred to as O-CU-UP, and the RU can also be referred to as O-RU. In different systems, the CU (or CU-CP and CU-UP), DU or RU can also have different names, but those skilled in the art can understand their meanings. Any one of the CU (or CU-CP, CU-UP), DU and RU in the present application can be realized by a software module, a hardware module, or a combination of a software module and a hardware module.

[0063] The access network device (network element module) of the ORAN and the corresponding relationship of the protocol layer functions that can be implemented are as shown in the following Table 1:

[0064] Table 1

[0065] In the present application, the communication device for realizing the access network function as described above can be an access network device, can be a network device having part of the function of the access network, or can be a device capable of supporting the realization of the access network function, such as a chip system, a hardware circuit, a software module, or a hardware circuit plus a software module, which can be installed in the access network device or used in matching with the access network device. In the method of the present application, the communication device for realizing the function of the access network device is taken as an example for description.

[0066] The core network device involved in the embodiments of the present application refers to a device in the CN that provides service support for a terminal. Currently, examples of some core network devices are: an access and mobility management function (AMF) entity, a session management function (SMF) entity, a user plane function (UPF) entity, and the like, which are not listed one by one here. Among them, the AMF entity can be responsible for access management and mobility management of the terminal; the SMF entity can be responsible for session management, such as session establishment of a user; and the UPF entity can be a functional entity of the user plane, mainly responsible for connecting external networks. It should be noted that the entity in the present application can also be referred to as a network element or a functional entity, for example, the AMF entity can also be referred to as an AMF network element or an AMF functional entity, and for another example, the SMF entity can also be referred to as an SMF network element or an SMF functional entity, and the like.

[0067] It should be understood that the number and type of each device in the communication system shown in FIGS. 1A-1C are only illustrative, and the present application is not limited thereto. In actual applications, more terminal devices, more access network devices, and other network elements, such as network elements for implementing artificial intelligence functions, can also be included in the communication system.

[0068] The related technologies of the present embodiments are described below.

[0069] 1. Handover

[0070] In the prior art, a plurality of different L3 handover types are introduced, including basic handover, CHO, and DAPS. In L3 handover, the change of the serving cell is triggered by L3 measurement and is completed based on RRC signaling (including an RRC reconfiguration message with a synchronization information element). The change of the serving cell can be a change of the primary cell and a change of the primary secondary cell. In L3 handover, a high-level reconfiguration (i.e., RRC (L1) / PDCP layer (L2)) and / or a reset of the bottom layer (e.g., the MAC layer and the physical layer) are required. Therefore, compared with beam handover without explicit RRC signaling, L3 handover causes longer latency, larger signaling overhead, and longer interruption latency.

[0071] LTM was then introduced to reduce mobility latency. LTM enables a change of the serving cell based on L1 / L2 signaling. Specifically, a base station instructs a UE to change the serving cell through a cell switch command carried by a MAC CE based on an L1 measurement report reported by the UE. The cell switch command indicates a base station candidate cell configuration, which is one of at least one candidate cell configuration previously sent to the UE by the base station through RRC signaling.

[0072] LTM supports intra-DU and inter-DU mobility (source cell and target cell of the handover procedure belong to the same DU / different DU, LTM maximizes the retention of high-layer configuration and minimizes the change of low-layer configuration, and the security key is also not required to be updated during LTM handover, such as intra-gNB target cell handover, user plane is not required to be reset, avoiding data loss and data recovery delay. In addition, continuous LTM is supported, which refers to multiple times of UE switching between LTM candidate cells without RRC reconfiguration by the network side in the process.

[0073] 2. LTM procedure

[0074] Referring to FIG. 1D, FIG. 1D is a schematic diagram of an intra-gNB LTM procedure provided by an embodiment of the present application. As shown in FIG. 1D, the intra-gNB LTM procedure, i.e., the DU (source cell) of the source base station and the DU (target cell) of the target base station belong to the same CU management of the base station (intra-gNB), can be extended to the inter-gNB LTM procedure, i.e., the DU (source cell) of the source base station and the DU (target cell) of the target base station belong to the CU management of different base stations (inter-gNB), and the DU of the target base station is managed by the CU of the target base station.

[0075] Specifically, the LTM procedure includes the following steps:

[0076] 1. The UE sends an L3 measurement report to the CU of the base station.

[0077] 2. The DU of the base station decides to initiate an LTM configuration procedure, prepares candidate cell configuration, and sends an RRC reconfiguration message including the LTM candidate cell configuration to the UE.

[0078] 3. The UE sends an RRC reconfiguration complete message to the CU of the base station.

[0079] 4. Before receiving the cell switch command, the UE can perform DL synchronization with candidate cells (4a in the figure), and the UE can perform UL synchronization with candidate cells (4b in the figure).

[0080] 5. The UE performs L1 measurement on the candidate cell configured in step 2, and sends the L1 measurement result to the DU of the source base station.

[0081] 6. The DU of the source base station decides to perform LTM handover to the target cell (DU of the target base station), the DU of the source base station sends a cell handover command carried by a MAC CE to the UE, including the configuration information of the target cell such as configuration ID.

[0082] 7. The UE applies the configuration of the target cell to access the target cell in a random access (RA) or RA-free manner.

[0083] 8. When the UE considers that the LTM cell handover is successfully performed, the UE sends an RRC reconfiguration complete message to the target cell (CU of the base station to which the target cell belongs).

[0084] In continuous LTM, steps 4-8 are repeated multiple times using the candidate cell configuration in step 2.

[0085] 3. MRO mechanism

[0086] In order to reduce the problems such as connection failure, unnecessary handover across systems, ping-pong handover across systems, failure of primary and secondary cell change, failure of cross-system voice fallback, and failure of fast primary cell group recovery caused by unreasonable network parameter settings, the system currently supports the MRO mechanism. MRO is an important mechanism for network self-optimization. When the UE occurs an abnormal situation related to mobility (such as connection failure), the UE reports the abnormal parameters related to mobility to the base station, and the base station can analyze and optimize the network parameters based on the related parameters reported by the UE. Specifically, the base station adjusts the mobility parameters based on the reports reported by the UE, such as radio link failure (RLF) reports and successful handover reports (SHR). Among them, the mobility parameters are parameters that may be used in the judgment of the handover process, such as the threshold of the handover and the target cell of the handover.

[0087] 4. Connection failure

[0088] Connection failure may occur during the handover process of the serving cell. In order to analyze the connection failure, the UE reports the RLF report to the base station, and the base station receiving the RLF report forwards the RLF report to the serving base station (also known as the last serving base station) when the connection failure occurs. One of the functions of MRO is connection failure cause analysis / detection, that is, to detect whether the connection failure is caused by early handover, late handover, or handover to an incorrect cell. Based on the received RLF report, the last serving gNB performs detection of the connection failure, and the specific detection method is as follows:

[0089] Late handover: the UE has no recent handover before the connection failure. For example, the timer information reported by the UE does not exist or is greater than the configured time threshold. Or, if conditional handover (CHO) is configured but the UE does not perform CHO before the connection failure, for example, the timer information reported by the UE does not exist or is greater than the configured time threshold.

[0090] Early handover: the UE has recently performed a handover before the connection failure. For example, the timer information reported by the UE is less than the configured time threshold, the first cell that the UE attempts to reestablish or the cell that the UE successfully reconnects is the cell that served the UE when the last handover was initiated, or in the case of DAPS handover, fallback to the source cell configuration.

[0091] Handover to an error cell: the UE has recently performed a handover before the connection failure. For example, the timer information reported by the UE is less than the configured time threshold, the first cell that the UE attempts to reestablish or the cell that the UE successfully reconnects or the cell that the UE attempts to recover CHO is neither the cell that served the UE when the last handover was initiated nor the serving cell or handover target cell of the UE when RLF occurs.

[0092] The timer information reported by the UE indicates the time elapsed from the last handover initiation to the connection failure, or the time elapsed from CHO execution to the connection failure. The timer information reported by the UE is included in the RLF report. The time threshold is configured by OAM to the base station to support detection of mobility optimization.

[0093] The above connection failure detection is the connection failure detection in the L3 handover mobility scenario in the existing MRO mechanism. The connection failure detection process is performed by the CU in the base station, for example, the CU of the last serving base station determines the connection failure reason according to whether the timer information reported by the UE is greater than the preset time threshold, such as the connection failure reason being one of the above early handover, late handover, and handover to an error cell, and therefore the preset time threshold is configured by the operation administration and maintenance (OAM) entity to the CU of the base station.

[0094] However, the existing MRO mechanism does not consider how to implement the LTM connection failure detection process. And if the LTM connection failure detection process and problem analysis are implemented according to the connection failure detection of L3 handover, it may cause problems such as low detection accuracy and low efficiency of the detection process, and may not be able to detect the mobility parameter problem of LTM.

[0095] Based on this, referring to FIG. 2, FIG. 2 is a flowchart of a communication method according to an embodiment of the present application, as shown in FIG. 2, the method comprises:

[0096] 201、the first network element sends first information to the first DU, and correspondingly, the first DU receives the first information. The first information is used to determine the cause of LTM connection failure.

[0097] 202、the first CU sends an RLF report to the first DU, and correspondingly, the first DU receives the RLF report.

[0098] The first DU can first acquire the first information and then acquire the RLF report, or first acquire the RLF report and then acquire the first information, or simultaneously acquire the first information and the RLF report. The present scheme is not limited in this way.

[0099] In the embodiment of the present application, the first network device is included, and the first DU is included in the first network device. The specific structure of the first network device and the first DU can be referred to the related description of the foregoing FIG. 1B or FIG. 1C, which will not be described here again.

[0100] Optionally, the first information is a first time threshold.

[0101] Exemplarily, the first DU acquires the first time threshold, and the first DU determines the cause of connection failure based on the first time threshold. Exemplarily, the first DU determines the cause of LTM connection failure according to the first time threshold and the timer information (for example, the time of UE in the last switching execution / initiation to connection failure) reported by UE in the RLF report, including late switching, early switching or switching to an error cell, etc.

[0102] In the case where the first information is the first time threshold, the first network element can be the first CU, and the first CU sends the first information to the first DU. The first time threshold in the first CU can come from the OAM entity configuration. Moreover, the first time threshold can be a time threshold specially set for LTM by the OAM entity, or can be a time threshold commonly used in LTM and L3 switching, that is, the time threshold configured by the OAM to the base station in the prior art to support mobility optimization detection.

[0103] Alternatively, the first network element can be an OAM entity, that is, the OAM entity configures the first time threshold for the first DU.

[0104] Optionally, the first information is indication information of the cause of LTM connection failure.

[0105] Exemplarily, the first DU receives the indication information of the cause of LTM connection failure, and then directly acquires the cause of LTM connection failure without the first DU detecting the cause of LTM connection failure.

[0106] In a case that the first information is the indication information of the cause of the LTM connection failure, the first network element can be a first CU, and before the first CU sends the indication information of the cause of the LTM connection failure to the first DU, the first CU determines the cause of the LTM connection failure according to a first time threshold configured by an OAM entity, and sends the cause of the LTM connection failure to the first DU.

[0107] Optionally, the first information is a cell radio network temporary identifier (C-RNTI) used by the terminal device in the first DU or the source cell.

[0108] Exemplarily, the first DU acquires a cell radio network temporary identifier (C-RNTI) used by the terminal device in the first DU or the source cell, and a first network element is a first CU, and the first CU performs analysis of the cause of the connection failure.

[0109] The first CU indicates the C-RNTI of the terminal device in the source cell to the first DU as the first information based on a mapping relationship between the C-RNTI of the terminal device in the target cell in the RLF report and the C-RNTI of the target cell and the C-RNTI of the source cell stored by the first CU, wherein the source cell belongs to the first DU.

[0110] The first DU identifies the terminal device that has ever connected to the source cell or the first DU before the connection failure occurs and the context related to the terminal device based on a cell radio network temporary identifier (C-RNTI) used by the terminal device in the first DU or the source cell.

[0111] Optionally, the first information is carried in information outside the RLF report container, and the RLF report container is used to carry the RLF report, so that the RLF report and the first information can be sent to the first DU at the same time, and the first DU can jointly analyze the two.

[0112] Exemplarily, the first CU sends the RLF report to the first DU, and the RLF report is carried in an RLF report container, and at the same time, the first CU sends the first information to the first DU, and the first information is not carried in the RLF report container but in information outside the RLF report container. In this way, the processing and operation of the RLF report are avoided.

[0113] Exemplarily, when the first CU sends the RLF report or the first information to the first DU, the first CU can be a CU in the first network device, and exemplarily, in the LTM procedure in the same gNB, the source cell and the candidate cell belong to the same CU management, and the first CU sends the RLF report or the first information through the F1 interface; or the first CU can be a CU in the second network device, and exemplarily, in the LTM procedure across gNBs, the source cell and the candidate cell belong to different CU managements, and the source cell and the target cell of the LTM switching can belong to different CU managements, and the CU of the second device can send the RLF report or the first information to the CU of the first device, and the CU of the first device sends the RLF report or the first information to the first DU through the F1 interface.

[0114] 203. The first DU performs cause analysis of the LTM connection failure.

[0115] Exemplarily, the first DU performs cause analysis of the LTM connection failure, that is, determines the cause of the LTM connection failure based on the first information. The cause of the LTM connection failure is determined based on the first information, or the cause of the LTM connection failure is determined based on the first information and other information (for example, the RLF report). Specifically, after the first DU receives the first information, the cause of the LTM connection failure can be determined according to the method described above. Further, the first DU can determine whether the root cause of the LTM connection failure is the first DU itself, and if so, the mobility parameters are optimized, for example, the parameters of the target cell of the handover and the handover timing are optimized, so as to reduce the probability of the LTM connection failure.

[0116] It can be seen that in the embodiments of the present application, the first information is received by the DU, and the cause of the LTM connection failure is determined based on the first information. Therefore, the DU can efficiently perform the LTM connection failure analysis, problem detection and possible mobility parameter optimization, thereby reducing the probability of the LTM connection failure and improving the accuracy of the LTM switching decision.

[0117] The above embodiments briefly introduce the way in which the first DU obtains the first information and determines the LTM connection failure analysis based on the first information. The following embodiments will introduce in detail the way in which the first DU obtains different first information from different network elements.

[0118] Referring to FIG. 3A, FIG. 3A is a flowchart of another communication method provided by the embodiments of the present application. As shown in FIG. 3A, the method includes the following steps.

[0119] 301a. The OAM entity configures a first time threshold for the first DU. Correspondingly, the first DU obtains the first time threshold.

[0120] In the embodiments of the present application, the first information is a first time threshold, and the first time threshold is configured by the OAM entity to the first DU directly. The first time threshold can be a time threshold specially set for the LTM, or can be a time threshold commonly used in the LTM and the L3 handover, that is, the time threshold configured by the OAM to the base station in the prior art to support mobility optimization detection.

[0121] Alternatively, step 301a can also be replaced by step 301b: the first CU sends the first time threshold to the first DU. Correspondingly, the first DU receives the first time threshold.

[0122] The connotation of the first time threshold is the same as described above, and will not be repeated.

[0123] The first time threshold in the first CU can be configured by the OAM entity.

[0124] 302. The first CU sends an RLF report to the first DU. Correspondingly, the first DU receives the RLF report.

[0125] The first CU can be the last serving CU, that is, the CU to which the serving cell of the UE belongs before the connection failure occurs. The first CU receives the RLF report from the UE, which is related to the LTM, that is, the RLF report related to the LTM connection failure. The first CU can forward the RLF report to the first DU.

[0126] The first CU sending the RLF report to the first DU can include the following three cases:

[0127] 302a. The first DU is the last serving DU. The first CU is the last serving CU, and the last serving DU (the first DU) belongs to the last serving CU managed by the first CU. Therefore, the first CU can send the RLF report to the first DU through the F1 interface (as shown in FIGS. 3B and 3C).

[0128] Correspondingly, the aforementioned first time threshold can also be sent to the first DU by the OAM entity or the first CU, and the first CU sends the first time threshold to the first DU in the same way as the aforementioned RLF report.

[0129] 302b. In the case of intra-gNB LTM, the first DU is a DU in the source serving network device and / or the target serving network device (source DU and / or target DU, the DU to which the handover source cell belongs is the source DU, and the DU to which the handover target cell belongs is the target DU), and the source CU and the candidate DU (the target DU) belong to the same CU managed by the first CU. The first CU sends the RLF report (intra-gNB) to the source DU and / or the target DU respectively (as shown in FIG. 3B).

[0130] Correspondingly, the aforementioned first time threshold value can also be sent by the OAM entity or the first CU to the source DU and the target DU respectively.

[0131] 302c, the first DU is the source DU and / or the target DU in the case of inter-gNB LTM. Possible way one, the first CU as the last serving CU can be the source CU, the first CU manages the source DU, the target DU is managed by the second CU, the first CU can send the RLF report to the source DU directly, the first CU can send the RLF report to the second CU, and the second CU sends the RLF report to the target DU; or, possible way two, the first CU as the last serving CU can be the target CU, the target CU manages the target DU, the source CU is managed by the second CU, the first CU can send the RLF report to the target DU directly, the first CU can send the RLF report to the second CU, and the second CU sends the RLF report to the source DU. (As shown in FIG. 3C).

[0132] Correspondingly, the aforementioned first time threshold value is sent by the OAM entity to the source DU and / or the target DU respectively, or sent by the first CU to the DU managed by itself, and sent by the second CU to the DU managed by itself.

[0133] The first DU receives the RLF report sent by the first CU, and the first DU acquires the first time threshold value from the OAM or the first CU or the CU, which can acquire the first time threshold value before acquiring the RLF report, or acquire the RLF report before acquiring the first threshold value, or acquire the first time threshold value and the RLF report at the same time, and the present scheme is not limited.

[0134] 303, the first DU determines the cause of the LTM connection failure based on the first time threshold value.

[0135] For example, the RLF report can include timer information indicating time information from the last LTM handover execution to the connection failure. If the timer information does not exist or is greater than (or equal to) the first time threshold, it is shown that no LTM handover is performed before the LTM connection failure, and the cause (type) of the LTM connection failure can be late handover; if the timer information is less than (or equal to) the first time threshold (indicating that LTM handover is performed before LTM connection failure), the first cell that the UE attempts to reconnect or the successfully reconnected cell is the cell serving the UE when the last handover is initiated or the cell sending the last LTM handover command to the UE, and the cause (type) of the LTM connection failure can be early handover; if the timer information is less than the first time threshold (indicating that LTM handover is performed before LTM connection failure), the first cell that the UE attempts to reconnect or the successfully reconnected cell is neither the cell serving the UE when the last handover is initiated (the cell sending the last LTM handover command to the UE) nor the serving cell of the UE or the handover target cell when the RLF occurs, and the cause (type) of the LTM connection failure can be handover to an incorrect cell.

[0136] Further, the first DU can perform root cause analysis of the LTM connection failure, and if it is determined that the LTM connection failure root cause occurs in the first DU, the first DU performs optimization of mobility parameters, etc. If the first DU determines that the connection failure root cause is not in the first DU, or that the connection failure root cause occurs in other DUs or CUs, the first DU can also indicate to the first CU that the connection failure root cause is not in the first DU, or that the connection failure root cause occurs in other DUs or CUs. The CU is the CU compared to the DU, which can refer to the first CU or the CU initiating the LTM procedure, or the CU sending the LTM candidate cell configuration for the UE. The other DU can be one or more DUs other than the first DU.

[0137] Optionally, in the case of 302a described above, assuming an intra-gNB scenario, the method can further include step 304, the first DU sending LTM connection failure cause information to the first CU. Correspondingly, the first CU receives the LTM connection failure cause information (as shown in FIG. 3B). It can also include 305a, the first CU sending LTM connection failure cause information to other DUs. Correspondingly, the other DUs receive the LTM connection failure cause information.

[0138] Optionally, in the case of 302a, assuming inter-gNB scenario, the first DU and the other DUs belong to different gNBs, the first DU determines the cause of the LTM connection failure, and the first DU can further perform step 304, and the first DU sends the cause information of the LTM connection failure to the first CU. Correspondingly, the first CU receives the cause information of the LTM connection failure (as shown in FIG. 3C). Further comprising 305b, the first CU sends the cause information of the LTM connection failure to the second CU, and the second CU sends the cause information of the LTM connection failure to the other DUs managed by the second CU. Correspondingly, the other DUs receive the cause information of the LTM connection failure.

[0139] It can be seen that, in the embodiments of the present application, the first DU receives the first time threshold from the OAM entity or the first CU, and detects / analyzes the cause of the LTM connection failure. This enables the DU to efficiently perform LTM connection failure analysis, problem detection, and possible mobility parameter optimization according to the known cause of the LTM connection failure, reduces the probability of LTM connection failure, and improves the accuracy of LTM handover decision.

[0140] In addition, obtaining the first time threshold from the OAM entity can reduce the number of interactions between network elements or entities. Obtaining the first time threshold from the first CU reduces the information interaction between the OAM and the DU.

[0141] Referring to FIG. 4, FIG. 4 is a flowchart of another communication method provided by the embodiments of the present application. As shown in FIG. 4, the method comprises the following steps:

[0142] 401. The first CU determines the cause of the LTM connection failure based on the first time threshold.

[0143] In the embodiments of the present application, the first CU detects / analyzes the cause of the LTM connection failure based on the first time threshold, and possible ways are referred to the above embodiments. The RLF report in the first CU can be reported by the UE or forwarded by other CUs. The first time threshold can be configured by the OAM entity or other management entity. Therefore, the method can further comprise the following steps:

[0144] 4001. The OAM entity configures the first time threshold to the first CU. Correspondingly, the first CU obtains the first time threshold.

[0145] 4002. The first CU receives the RLF report. Correspondingly, the UE or other CU sends the RLF report to the first CU.

[0146] The process of the first CU determining the cause of the LTM connection failure based on the first time threshold can refer to the related description of the foregoing step 303, and will not be repeated here. The steps 4001 and 4002 do not have a strict order.

[0147] 402、The first CU sends indication information indicating the cause of the LTM connection failure, and the first DU correspondingly receives the indication information.

[0148] The indication information indicates one of early handover, late handover, or handover to a wrong cell as the cause of the LTM connection failure. The indication information can be an enumerated value, or can be a bitmap, with the number of bits corresponding to the number of causes of the LTM connection failure. For example, three bits are used to indicate three causes of the LTM connection failure. 001 indicates late handover, 010 indicates early handover, and 100 indicates handover to a wrong cell. Alternatively, two bits can be used, with 00, 01, and 10 respectively indicating one type of LTM connection failure.

[0149] 403、The first DU determines the cause of the LTM connection failure based on the indication information.

[0150] The first DU determines the cause of the LTM connection failure, and efficiently and accurately analyzes the mobility parameter problem.

[0151] As can be seen, in the embodiments of the present application, the DU receives indication information from the first CU indicating the cause of the LTM connection failure, so that the DU can quickly and directly learn the cause of the LTM connection failure, and more fully and timely participate in the decision-making process after the LTM connection failure, thereby improving the accuracy and efficiency of the LTM connection failure processing process. In addition, the CU determines the cause of the LTM connection failure and indicates it to the DU, which more accurately identifies the DU that needs to send an RLF report, and can reduce the analysis / detection process of the DU for the cause of the LTM connection failure, thereby reducing the energy consumption of the DU.

[0152] Referring to FIG. 5, FIG. 5 is a flowchart of another communication method provided by the embodiments of the present application. As shown in FIG. 5, the method includes the following steps.

[0153] 501、The terminal device sends a cell radio network temporary identifier C-RNTI used by the terminal device in the first DU or a source cell to the first DU. Correspondingly, the first DU receives the cell radio network temporary identifier C-RNTI used by the terminal device in the first DU or the source cell.

[0154] 502、The first DU determines the cause of the LTM connection failure based on the cell radio network temporary identifier C-RNTI used by the terminal device in the first DU or the source cell.

[0155] In the embodiments of the present application, the first DU obtains the cell radio network temporary identifier C-RNTI used in the first DU or the source cell from the first CU, for connection failure problem analysis and mobility parameter optimization adjustment.

[0156] The first CU sends the C-RNTI to the first DU in the manner described above in the first CU sending the first information to the first DU in the intra-gNB and inter-gNB embodiments.

[0157] The first CU stores the mapping relationship between the target cell C-RNTI and the source cell C-RNTI, and obtains the cell radio network temporary identifier C-RNTI used by the terminal device in the first DU or the source cell based on the C-RNTI used by the terminal device in the target cell in the RLF report, and indicates the cell radio network temporary identifier C-RNTI used by the terminal device in the first DU or the source cell to the first DU.

[0158] The first DU identifies the terminal device that has ever connected to the source cell or the first DU before the connection failure occurs and the context related to the terminal device based on the cell radio network temporary identifier C-RNTI used by the terminal device in the first DU or the source cell, so that the DU can efficiently perform LTM connection failure analysis, problem detection and possible mobility parameter optimization, reduce the probability of LTM connection failure, and improve the accuracy of LTM handover decision.

[0159] The above embodiments describe the method for the DU to determine the cause of LTM connection failure. After the DU determines the cause of LTM connection failure, it can further perform root cause analysis of LTM connection failure. The following embodiments will be described in detail.

[0160] Referring to FIG. 6A, FIG. 6A is a flowchart of a communication method according to an embodiment of the present application. The method includes the following steps:

[0161] 601. The first network element sends first information to the first DU, and correspondingly, the first DU receives the first information. The first information is used to determine the cause of LTM connection failure.

[0162] 602. The first CU sends an RLF report to the first DU, and correspondingly, the first DU receives the RLF report.

[0163] 603. The first DU determines the cause of LTM connection failure based on the first information.

[0164] Steps 601-603 are the process for the first DU to determine the cause of LTM connection failure. Therefore, the description of steps 601-603 can refer to the related description of steps 201-203 described above. Furthermore, the first information can be any one of the information described in the embodiments of FIGS. 3A-5, and correspondingly, the first network element can be any one of the network elements described in the embodiments of FIGS. 3A-5. Details are not repeated here.

[0165] The first CU can be a CU in the last serving network device, i.e., a last serving CU.

[0166] The first CU sending the RLF report to the first DU can include the following three cases:

[0167] 602a, the first DU is a last serving DU. The first CU is a last serving CU, and the last serving DU (the first DU) belongs to the last serving CU management, so the first CU can send the RLF report to the first DU through the F1 interface (as shown in FIGS. 6B and 6C).

[0168] 602b, in the case of intra-gNB LTM, the first DU is a DU (source DU and / or target DU) in the source serving network device and / or the target serving network device (the DU to which the handover source cell belongs is the source DU, and the DU to which the handover target cell belongs is the target DU), and the source CU and the candidate DU (the target DU) belong to the same CU management, i.e., the first CU management. The first CU sends the RLF report (intra-gNB) to the source DU and / or the target DU, respectively (as shown in FIG. 6B).

[0169] 602c, in the case of inter-gNB LTM, the first DU is a source DU and / or a target DU. Possible way one, the first CU as a last serving CU can be a source CU, the first CU manages the source DU, and the target DU is managed by a second CU. The first CU can directly send the RLF report to the source DU, and the first CU can send the RLF report to the second CU, and the second CU sends the RLF report to the target DU. Or, possible way two, the first CU as a last serving CU can be a target CU, the target CU manages the target DU, and the source CU is managed by a second CU. The first CU can directly send the RLF report to the target DU, and the first CU can send the RLF report to the second CU, and the second CU sends the RLF report to the source DU. (One of the cases is shown in FIG. 6C).

[0170] The step of the first CU sending the RLF report to the first DU and the step of the first CU sending the first information to the first DU can be sent at the same time, i.e., the RLF report and the first information are sent in one message. In one implementation, the first CU sends the first information to the first DU while also sending the RLF report to the first DU. The first information is carried in the information outside the RLF report container.

[0171] The step of the first CU sending the RLF report to the first DU and the step of sending the first message can also be sent in sequence, and the sending order is not limited.

[0172] If the first DU determines the cause of the LTM connection failure by using the RLF report, and the first DU has obtained the RLF report from the first CU, step 602 (or 602a, 602b, or 602c) can be omitted.

[0173] If the first network element is the first CU, the first network element and the first CU can be combined.

[0174] 604. The first DU performs root cause analysis on the LTM connection failure.

[0175] The first DU receives the RLF report, determines the cause of the connection failure, and further determines whether the root cause of the LTM connection failure occurs in the first DU. The first DU determines that the root cause of the LTM connection failure occurs in the first DU. Or the first DU determines that the DU corresponding to the root cause of the LTM connection failure is another DU or a CU. The other DU refers to one or more DUs other than the first DU. The CU is the CU compared with the DU, which can refer to the first CU or the CU initiating the LTM process, or the CU sending the LTM candidate cell configuration to the UE.

[0176] Optionally, the method can further include: 605. If the first DU determines that the root cause of the LTM connection failure occurs in the first DU, the first DU optimizes the mobility parameter.

[0177] For example, the first DU optimizes the mobility parameter according to the RLF report, for example, optimizes the parameters such as handover time, target cell of handover, and the like, to reduce the probability of LTM connection failure.

[0178] If the first DU determines that the DU corresponding to the root cause of the LTM connection failure is another DU or a CU, it includes two cases corresponding to the aforementioned steps 602a, 602b, or 602c:

[0179] Case 1: The first DU is the source DU and / or the target DU, and the first DU performs LTM connection failure root cause analysis. If it is the cause of the connection failure, the mobility parameter is optimized.

[0180] Case 2: The first DU is the last serving DU, and the root cause of the LTM connection failure is not the first DU. After step 602a, step 606 can also be included, in which the first DU sends second information to the first CU, indicating that the root cause of the LTM connection failure corresponds to other DUs or CUs. Other DUs are one or more DUs other than the first DU. For example, when the last serving DU is the source DU, i.e., the first DU is the source DU, the first DU indicates to the first CU that the root cause of the LTM connection failure occurs in the CU, and there can be no second DU; when the last serving DU is the target DU, i.e., the first DU is the target DU, the second DU is the source DU, and the first DU indicates to the first CU that the root cause of the LTM connection failure corresponds to the source DU or the CU.

[0181] Optionally, step 602a can be combined with step 304 in the foregoing embodiments, i.e., the cause of the LTM connection failure can also be carried in the second information.

[0182] After the first CU receives the second information, step 607a can also be included, in which the first CU sends an RLF report to the second DU (as shown in FIG. 6B). Or step 607b can also be included, in which the first CU sends an RLF report to the second CU, and the second CU forwards the RLF report to the second DU (as shown in FIG. 6C). Or step 607c can also be included, in which the first CU performs connection failure analysis, or the first CU sends an RLF report to the CU that initiated the LTM procedure or the CU configured with the LTM candidate cell for the UE, to instruct the corresponding CU to perform connection failure analysis (not shown in the figure).

[0183] Optionally, in the case where step 607a or 607b is combined with step 602a, the first CU also sends the cause of the LTM connection failure to the second DU (as shown in FIG. 6B and FIG. 6C).

[0184] For example, according to the second information, the first CU determines whether it needs to send an RLF report and / or LTM connection failure cause indication information to the second DU. For example, when the last serving DU is the source DU, there is no second DU, and the CU does not need to continue forwarding the RLF report, and the CU performs connection failure root cause analysis. When the last serving DU is the target DU, the second DU is the source DU. Alternatively, the second DU is a subset or all of the other DUs other than the first DU among the candidate DUs. For example, assuming that two DUs are involved in the LTM procedure, the other DU is equivalent to the second DU, and assuming that three or more DUs are involved in the LTM procedure, the second DU can be all or part of the other DUs.

[0185] After the second DU determines the root cause of the LTM connection failure, the second DU can also perform mobility parameter optimization.

[0186] As can be seen, in the embodiments of the present application, the first DU can determine whether the root cause of the LTM connection failure occurs in itself, and if so, further mobility parameter optimization can be performed, and if not, the information can be sent to the first CU so that the first CU instructs other DUs or the CU itself to perform root cause analysis of the LTM connection failure. This process directly determines the root cause of the LTM connection failure by the DU, improving the determination efficiency and accuracy. And it helps to improve the effectiveness of the further mobility parameter optimization by the DU.

[0187] Please refer to FIG. 7, which is a structural schematic diagram of a communication apparatus provided by an embodiment of the present application. The communication apparatus can be used to execute any of the methods in the foregoing embodiments.

[0188] As shown in FIG. 7, the communication apparatus includes a processing module 1501 and a transceiver module 1502. The processing module 1501 can be one or more processors, and the transceiver module 1502 can be a transceiver or a communication interface. The communication apparatus can be used to implement the functions of the devices such as the first device and the second device in any of the method embodiments. These devices can be hardware devices, software functions running on special hardware, or virtualized functions instantiated on a platform (e.g., a cloud platform). Optionally, the communication apparatus can further include a storage module 1503 for storing the program code and data of the communication apparatus.

[0189] In the first instance, the communication apparatus can be used as a network device or a chip in a network device in FIGS. 2-6C and execute the steps performed by the DU in the method embodiments. The transceiver module 1502 is used to support communication with the CU and the like. The processing module 1501 can be used to support the execution of the actions performed by the DU in the method embodiments except for sending and receiving.

[0190] Specifically, the transceiver module 1502 receives the RLF report and the first information from the first network element, wherein the first information is used to determine the cause of the layer 1 or layer 2 triggered mobility LTM connection failure; and the processing module 1501 is used to determine the cause of the LTM connection failure based on the first information.

[0191] In a feasible implementation, the first information is a first time threshold; or the first information is indication information of the cause of the LTM connection failure; or the first information is a cell radio network temporary identifier C-RNTI used by the terminal device in the first DU or the source cell.

[0192] In a feasible implementation, when the first information is a first time threshold, the first network element is a first centralized unit CU or an operation and maintenance management OAM entity.

[0193] In an implementable embodiment, the first information is indication information of a cause of the LTM connection failure, and the first network element is the first CU.

[0194] In an implementable embodiment, the first information is a cell radio network temporary identifier (C-RNTI) used by the terminal device in the first DU or the source cell, and the first network element is the first CU.

[0195] In an implementable embodiment, the processing module 1501 is further configured to perform root cause analysis on the LTM connection failure.

[0196] In an implementable embodiment, the processing module 1501 is further configured to, if it is determined that the root cause of the LTM connection failure corresponds to another DU or CU, send, in combination with the transceiver module 1502, second information to the first CU, the second information indicating that the root cause of the LTM connection failure is in the other DU or CU, the other DU being one or more DUs other than the first DU.

[0197] In an implementable embodiment, the second information further indicates the cause of the LTM connection failure.

[0198] In an implementable embodiment, the processing module 1501 is further configured to, if it is determined that the root cause of the LTM failure corresponds to the first DU, perform, by the first DU, mobility parameter optimization.

[0199] In an implementable embodiment, the RLF report is carried in an RLF report container, and the first information is carried in information outside the RLF report container.

[0200] In a second example, the communication apparatus can be a network device or a chip in a network device in FIGS. 2-6C and perform the steps performed by the network device in the above method embodiments. The transceiver module 1502 is configured to support communication with the DU. The processing module 1501 can be configured to support performing the actions of the above method embodiments performed by the CU, except for sending and receiving.

[0201] Specifically, the processing module 1501 or the transceiver module 1502 is configured to send first information for determining a cause of the LTM connection failure, and further configured to send an RLF report to the first DU.

[0202] In an implementable embodiment, the first information is a first time threshold, and the obtaining of the first information comprises: the transceiver module 1502 obtaining a first time threshold configured by an operation and maintenance management (OAM) entity.

[0203] In a possible implementation, when the first information is indication information of a cause of the LTM connection failure, the transceiver 1502 is configured to obtain a first time threshold configured by the OAM entity, and the transceiver 1502 is configured to obtain an RLF report reported by the terminal device; and the processing module 1501 is configured to analyze / detect the cause of the LTM connection failure.

[0204] In a possible implementation, the transceiver 1502 is further configured to: receive second information from the first DU, the second information indicating that a root cause of the LTM connection failure corresponds to another DU or a CU, and the another DU is one or more DUs other than the first DU; and send the first information to a second DU, the second DU being at least one of the another DUs.

[0205] In a possible implementation, the second information further indicates the cause of the LTM connection failure.

[0206] In a possible implementation, the RLF report is carried in an RLF report container, and the first information is carried in information outside the RLF report container.

[0207] Referring to FIG. 8, FIG. 8 is a structural schematic diagram of a simplified network device provided by an embodiment of the present application, which can be used as an implementation manner of the network device of the present application.

[0208] The network device includes a radio frequency signal transceiving and conversion part and a baseband part 42. The radio frequency signal transceiving and conversion part includes a receiving module 41 part and a sending module 43 part (which can also be collectively referred to as a transceiver module). The radio frequency signal transceiving and conversion part is mainly used for the transceiving of radio frequency signals and the conversion between radio frequency signals and baseband signals; the baseband part 42 is mainly used for baseband processing and controlling the network device, etc. The receiving module 41 can also be referred to as a receiver, a receiver, a receiving circuit, etc. The sending module 43 can also be referred to as a transmitter, a transmitter, a transmitter, a transmitting circuit, etc. The baseband part 42 is usually the control center of the network device, and can also be referred to as a processing module, which is used to execute the steps performed by the network device in any of the above methods. For details, please refer to the description of the related part above. The sending module 43 can include an antenna and a radio frequency circuit. The radio frequency circuit is mainly used for the conversion between baseband signals and radio frequency signals and the processing of radio frequency signals. The antenna is mainly used for the transceiving of radio frequency signals in the form of electromagnetic waves.

[0209] The baseband part 42 can include one or more single boards, each of which can include one or more processors and one or more memories, the processors being configured to read and execute programs in the memories to implement baseband processing functions and control of the network device. If there are multiple single boards, the single boards can be interconnected to increase processing capacity. As an optional implementation, the multiple single boards can also share one or more processors, or share one or more memories, or share one or more processors and one or more memories at the same time.

[0210] Referring to FIG. 9, FIG. 9 is a schematic diagram of a RAN chip structure provided by an embodiment of the present application, which can be used as another implementation of the network device of the present application.

[0211] The RAN chip is divided into CU, DU and RU. The CU is a platform that implements upper-layer L2 (data link layer) and L3 (network layer) functions. The Midhaul and Backhaul interfaces are used to carry traffic between the CU and the DU, and between the CU and the core network. The DU implements L1 and part of L2 functions, and the RU implements L1 (physical layer) computation and RF digital part functions. The Fronthaul and Backhaul interfaces are used to carry traffic between the RU and the DU, and between the CU and the DU. The integrated DU includes the above-mentioned DU and RU functions.

[0212] The CU / DU hardware includes a chassis platform, a mainboard, peripheral devices and cooling devices. The mainboard contains processing units, memories, internal I / O interfaces and external connection ports. The hardware accelerator design has an interface, and the hardware function components include storage of software, hardware and system debugging interfaces, and a single board management controller.

[0213] The DU system is usually implemented using a multi-core processor and one or more hardware accelerators. Part of the DU protocol stack can be implemented in software running on the multi-core processor, and the computation-intensive L1 and L2 functions can be offloaded to the FPGA / GPU-based hardware accelerator; or all L1 functions are offloaded to the FPGA / GPU-based hardware accelerator, and other protocol stack contents are implemented in software running on the processor; or all the protocol stack is implemented in software running on the processor. The hardware accelerator supports interconnection with an x86 or non-x86 processor. Similarly, the accelerator has a multi-channel PCIe interface pointing to the CPU, and is externally connected through GbE connection.

[0214] The RU includes three parts: an OPU (O-RAN Processing Unit) receives eCPRI frames from the O-RAN fronthaul and performs the fronthaul interface, the lowest layer L1 (encoding, scrambling, modulation, layer mapping, precoding), synchronization, beamforming, and resource unit mapping. The OPU can be implemented as a CPU, FPGA, or ASIC. A DPU (Digital Processing Unit of the O-RU) performs synchronization, DDC (digital down-conversion in the UL), DUC (digital up-conversion in the DL), CFR, and DPD to improve power amplifier efficiency by reducing the PAPR / ACLR of the RF front end; the DPU can be implemented as an FPGA or ASIC. The RF processing unit of the O-RU includes a transceiver module, an up / down converter, a power amplifier (PA), a low-noise amplifier (LNA), a Tx / Rx filter. All conversions between the analog and digital domains (DAC and ADC) (e.g., (RF sampling, using RF, IF, and LO mixing for frequency conversion in upconversion and downconversion) are performed within the transceiver module. Note that the physical and logical partitions within the RF processing unit do not require specific boundaries.

[0215] Referring to FIG. 10, FIG. 10 is a simplified structural diagram of a UE according to an embodiment of the present application, which is an implementation of the terminal device in the present application.

[0216] For the convenience of understanding and illustration, in FIG. 10, the UE takes a mobile phone as an example. As shown in FIG. 10, the UE includes at least one processor, and can further include a radio frequency circuit, an antenna, and an input / output device. The processor can be used to process communication protocols and communication data, and can also be used to control the UE, execute software programs, process data of the software programs, etc. The UE can further include a memory, which is mainly used to store software programs and data. These programs can be loaded into the memory when the communication device is manufactured, or can be loaded into the memory at a later time when needed. The radio frequency circuit is mainly used for conversion between baseband signals and radio frequency signals and processing of the radio frequency signals. The antenna is mainly used for receiving and transmitting radio frequency signals in the form of electromagnetic waves. The input / output device, such as a touch screen, a display screen, a keyboard, etc., is mainly used to receive data input by a user and output data to the user. It should be noted that some types of UE can not have an input / output device.

[0217] When a signal needs to be sent, the processor performs baseband processing on the data to be sent, and outputs the baseband signal to the radio frequency circuit. The radio frequency circuit performs radio frequency processing on the baseband signal, and sends the radio frequency signal in the form of electromagnetic waves through the antenna. When data is sent to the UE, the radio frequency circuit receives the radio frequency signal through the antenna, converts the radio frequency signal into a baseband signal, and outputs the baseband signal to the processor. The processor converts the baseband signal into data and processes the data. For ease of illustration, only one memory and one processor are shown in FIG. 10. In actual UE products, there can be one or more processors and one or more memories. The memory can also be referred to as a storage medium or a storage device, etc. The memory can be independent of the processor, or can be integrated with the processor. The embodiments of the present application do not limit this.

[0218] In the embodiments of the present application, the antenna and the radio frequency circuit with transceiving functions can be regarded as a receiving unit and a sending unit (which can also be collectively referred to as a transceiving unit) of the UE, and the processor with processing functions can be regarded as a processing unit of the UE. As shown in FIG. 10, the UE includes a receiving module 31, a processing module 32, and a sending module 33. The receiving module 31 can also be referred to as a receiver, a receiver, a receiving circuit, etc., and the sending module 33 can also be referred to as a transmitter, a transmitter, a transmitter, a transmitting circuit, etc. The processing module 32 can also be referred to as a processor, a processing board, a processing device, etc.

[0219] It can be understood that the processor in the embodiments of the present application can be a central processing unit (CPU), and can also be other general-purpose processors, digital signal processors (DSPs), application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs) or other programmable logic devices, transistor logic devices, hardware components, or any combination thereof. The general-purpose processor can be a microprocessor, or any conventional processor.

[0220] Optionally, the memory can also store data. The processor and the memory can be separately arranged or integrated together. The memory can be a non-volatile memory such as a hard disk drive (HDD) or a solid-state drive (SSD), and can also be a volatile memory such as a random-access memory (RAM). In the embodiments of the present application, the processor can also be a flash memory, a read-only memory (ROM), a programmable ROM (PROM), an erasable PROM (EPROM), an electrically EPROM (EEPROM), a register, a hard disk, a mobile hard disk, a CD-ROM, or any other form of storage medium well known in the art.

[0221] Optionally, the UE can include instructions (which can also be referred to as code or programs at times) that can be run on the processor.

[0222] Optionally, the UE can also include a transceiver and an antenna. The transceiver can be referred to as a transceiving unit, a transceiving module, a transceiver, a transceiving circuit, a transceiver, an input / output interface, etc., and is used to realize the transceiving function of the UE through the antenna.

[0223] The embodiments of the present application provide a communication system, which includes the terminal device and the network device.

[0224] The embodiments of the present application provide a computer readable storage medium, which stores computer instructions, and when the computer instructions are executed, the computer executes the method according to any one of the above methods.

[0225] The embodiments of the present application provide a computer program product, which includes computer program code, and when the computer program code is run by a computer, the computer executes the method according to any one of the above methods.

[0226] The embodiments of the present application provide a chip, which is coupled with a memory, and is used to read and execute program instructions in the memory, so that the device in which the chip is located implements the method according to any one of the above methods.

[0227] In the above embodiments, the description of each embodiment has its own focus, and the parts not described in detail in a certain embodiment can be referred to the relevant description of other embodiments. It should be noted that, for the foregoing method embodiments, in order to simply describe, they are all expressed as a combination of a series of actions, but those skilled in the art should know that the application is not limited to the order of the actions described, because according to the application, some steps can be performed in other order or simultaneously. Secondly, those skilled in the art should know that the embodiments described in the specification are all preferred embodiments, and the actions and modules involved are not necessarily necessary for the application.

[0228] In several embodiments provided in the present application, it should be understood that the disclosed device can be implemented by other ways. For example, the device embodiments described above are only schematic, for example, the division of the above units is only a logical function division, and there can be another division way in actual implementation, for example, a plurality of units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the coupling or direct coupling or communication connection between the units shown or discussed can be indirect coupling or communication connection through some interface, device or unit, and can be electrical or other forms.

[0229] The units described above as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, that is, they can be located in one place, or can be distributed on a plurality of network units. Part or all of the units can be selected according to actual needs to achieve the purpose of the embodiment scheme.

[0230] The above description and the above embodiments are only used to illustrate the technical solutions of the present application, but not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that the technical solutions recorded in the foregoing embodiments can be modified, or some technical features can be replaced by equivalent; and these modifications or replacements do not make the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A communication method characterized by comprising: The method comprises: A first distributed unit (DU) receives a radio link failure (RLF) report from a first CU; The first DU receives first information from a first network element, the first information being used to determine a cause of a layer 1 or layer 2 triggered mobility (LTM) connection failure; the cause of the LTM connection failure being one of early handover, late handover, or handover to a wrong cell; The first DU performs analysis of the cause of the LTM connection failure.

2. The method of claim 1, wherein the first information is a first time threshold; or The first information is indication information of the cause of the LTM connection failure; or The first information is a cell radio network temporary identifier (C-RNTI) used by a terminal device in the first DU or a source cell.

3. The method of claim 2, wherein, When the first information is the first time threshold, the first network element is a first centralized unit (CU) or an operation administration and maintenance (OAM) entity.

4. The method of claim 2, wherein, When the first information is the indication information of the cause of the LTM connection failure, the first network element is the first CU.

5. The method of claim 2, wherein, When the first information is the C-RNTI used by the terminal device in the first DU, the first network element is the first CU.

6. The method according to any one of claims 1 to 5, characterized in that, The method further comprises: the first DU performing root cause analysis of the LTM connection failure.

7. The method of claim 6, wherein, if the first DU determines that the root cause of the LTM connection failure occurs in another DU or CU, or the first DU detects that the root cause of the LTM connection failure is not in the first DU, the first DU sends second information to the first CU, the second information indicating that the root cause of the LTM connection failure occurs in another DU or CU, the another DU being one or more DUs other than the first DU.

8. The method of claim 7, wherein, The second information further indicates the cause of the LTM connection failure.

9. The method of claim 6, wherein, The method further comprises: If it is determined that the root cause of the LTM failure occurs in the first DU, the first DU performs mobility parameter optimization.

10. The method of claim 1, wherein, The RLF report is carried in an RLF report container, and the first information is carried in information outside the RLF report container.

11. A communication method, comprising: The method comprises: A first CU sends first information to a first DU, the first information being used to perform LTM connection failure analysis; The first CU sends an RLF report to the first DU.

12. The method of claim 11, wherein, The first information is a first time threshold; or The first information is indication information of the cause of the LTM connection failure; or The first information is a cell radio network temporary identifier (C-RNTI) used by a terminal device in the first DU or a source cell.

13. The method of claim 12, wherein, When the first information is the first time threshold, the method further comprises: The first CU obtains the first time threshold configured by an operation administration and maintenance (OAM) entity.

14. The method of claim 12, wherein, When the first information is the C-RNTI used by the terminal device in the first DU or the source cell, the method further comprises: The first CU obtains a cell radio network temporary identifier (C-RNTI) used by the terminal device in the first DU or the source cell based on a C-RNTI used by the terminal device in a target cell in the RLF report and a mapping relationship between a target cell C-RNTI and a source cell C-RNTI stored by the first CU.

15. The method of claim 12, wherein, When the first information is indication information of a reason for LTM connection failure, the method further includes: The first CU obtains a first time threshold configured by an OAM entity. The first CU determines the reason for LTM connection failure according to the first time threshold.

16. The method according to any one of claims 11-15, characterized in that, The method further includes: The first CU receives second information from the first DU, the second information indicating that a root cause of the LTM connection failure occurs in other DUs or CUs or indicating that the root cause of the LTM connection failure is not in the first DU, the other DUs being one or more DUs other than the first DU.

17. The method of claim 16, wherein, The method further includes: The first CU sends the first information to a second DU, the second DU being at least one of the other DUs.

18. The method of claim 16, wherein, The second information further indicates the reason for LTM connection failure.

19. The method of claim 11 or 17, wherein, The RLF report is carried in an RLF report container, and the first information is carried in information outside the RLF report container.

20. A communications device, characterized by The apparatus is configured to implement the method of any one of claims 1 to 10 or the method of any one of claims 11 to 19.

21. The apparatus of claim 20, wherein, The apparatus includes a network device or a chip.

22. A communication apparatus, comprising: The communication apparatus includes at least one processor coupled to a memory. The at least one processor is configured to execute computer programs or instructions stored in the memory, so that the method of any one of claims 1 to 10 or claims 11 to 19 is implemented.

23. A computer-readable storage medium, characterized in that, The computer readable storage medium stores a computer program which, when executed, causes the method of any one of claims 1 to 10 or claims 11 to 19 to be implemented.

24. A computer program, characterized in that, When the computer program is executed, the method of any one of claims 1 to 10 or claims 11 to 19 is implemented.

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