Source distribution unit, central unit, terminal device and method

Abstract

The embodiments of the present disclosure relate to a communication method, an apparatus, and a computer-readable medium, in which a source DU transmits first information on at least one candidate cell for a lower layer signaling-based cell change or addition to a CU, and receives second information on a target cell for the lower layer signaling-based cell change or addition from the CU. In this way, it is possible to define CU-DU interaction for L1 / L2-based mobility.

Description

[Technical field]

[0001] TECHNICAL FIELD Embodiments of the present disclosure relate generally to the field of telecommunications, and more particularly to a method, apparatus, and computer storage medium for communication based on lower layer signaling. [Background technology]

[0002] When a user equipment (UE) moves from the coverage area of ​​one cell to the coverage area of ​​another cell, it may be necessary to perform a serving cell change or addition or release. Currently, the serving cell change or addition or release is performed by a synchronous reconfiguration triggered by Layer 3 (L3) measurements and for primary cell (PCell) and primary secondary cell (PSCell) changes, triggered by radio resource control (RRC) signaling. All cases involve a full Layer 2 (L2) and Layer 1 (L1) reset, which causes longer delays, higher overhead and longer outage times than beam switching mobility.

[0003] Some solutions to the above problem have been proposed based on lower layer signaling, e.g., Layer 1 (L1) or Layer 2 (L2) signaling. In one solution, upon receiving lower layer signaling, the serving cell is changed to perform data transmission, which is also called L1 / L2-based mobility. Thus, the delay, overhead, and interruption time can be reduced. However, the central unit (CU)-distributed unit (DU) interface signaling needs to be further developed to support L1 / L2-based mobility procedures. Summary of the Invention [Problem to be solved by the invention]

[0004] In general, the exemplary embodiments of the present disclosure provide a method, apparatus, and computer storage medium for communications based on lower layer signaling. [Means for solving the problem]

[0005] In a first aspect, a method of communication is provided, the method including: transmitting, at a first DU, to a CU, first information regarding at least one candidate cell for a lower layer signaling based cell change or addition, and receiving, from the CU, second information regarding a target cell for the lower layer signaling based cell change or addition.

[0006] In a second aspect, a method of communication is provided, the method including: determining, at a first DU, a target cell for a lower layer signaling based cell change or addition, and sending, to a CU, third information indicating that the lower layer signaling based cell change or addition has been triggered for the target cell.

[0007] In a third aspect, a method of communication is provided, the method including: receiving, in a CU, from a first DU, first information related to at least one candidate cell for a lower layer signaling based cell change or addition, determining a target cell for the lower layer signaling based cell change or addition based on the first information, and transmitting, to the first DU, second information related to the target cell for the lower layer signaling based cell change or addition.

[0008] In a fourth aspect, a method of communication is provided, the method including receiving, at a CU, third information from a first DU indicating that a lower layer signaling-based cell change or add has been triggered for a target cell.

[0009] In a fifth aspect, a method of communication is provided, the method including: receiving, at a second DU, an indication from a CU indicating that a lower layer signaling based cell change or add is triggered for a target cell associated with the second DU; and sending an acknowledgement for the trigger to the CU.

[0010] In a sixth aspect, there is provided a DU, comprising a processor configured to cause the DU to perform a method according to the first, second or fifth aspect of the present disclosure.

[0011] In a seventh aspect, there is provided a CU, the CU comprising a processor configured to cause the CU to perform a method according to the third or fourth aspect of the present disclosure.

[0012] In an eighth aspect, there is provided a computer readable medium storing instructions which, when executed on at least one processor, cause the at least one processor to perform a method according to the first or second or fifth aspect of the present disclosure.

[0013] In a ninth aspect, there is provided a computer readable medium storing instructions which, when executed on at least one processor, cause the at least one processor to perform a method according to the third or fourth aspect of the present disclosure.

[0014] Other features of the present disclosure will become readily apparent from the following description. [Brief description of the drawings]

[0015] The above and other objects, features and advantages of the present disclosure will become more apparent from the following detailed description of several embodiments of the present disclosure in the accompanying drawings.

[0016] [Figure 1A] FIG. 1 illustrates an example communication network in which some embodiments of the present disclosure may be implemented.

[0017] [Figure 1B] FIG. 2 is a schematic diagram illustrating network protocol layer entities that may be established for a user plane (UP) protocol stack in an apparatus according to some embodiments of the present disclosure.

[0018] [Figure 1C] FIG. 2 is a schematic diagram illustrating network protocol layer entities that may be established for a control plane (CP) protocol stack in an apparatus according to some embodiments of the present disclosure.

[0019] [Figure 1D] FIG. 1 is a schematic diagram illustrating a central unit (CU) / distributed unit (DU) capable of implementing some embodiments of the present disclosure.

[0020] [Figure 1E] FIG. 2 is a schematic diagram illustrating a process of L1 / L2 based mobility in which some embodiments of the present disclosure can be implemented.

[0021] [Diagram 2] FIG. 2 is a schematic diagram illustrating a process of candidate cell configuration for L1 / L2-based mobility according to an embodiment of the present disclosure.

[0022] [Diagram 3] 1 is a schematic diagram illustrating a process of lower layer measurement configuration for L1 / L2 based mobility according to an embodiment of the present disclosure;

[0023] [Figure 4A] FIG. 2 is a schematic diagram illustrating a process of triggering L1 / L2-based mobility according to an embodiment of the present disclosure.

[0024] [Figure 4B]FIG. 2 is a schematic diagram illustrating another process for triggering L1 / L2-based mobility according to an embodiment of the present disclosure.

[0025] [Figure 4C] FIG. 13 is a schematic diagram illustrating yet another process for triggering L1 / L2-based mobility in accordance with an embodiment of the present disclosure.

[0026] [Diagram 5] FIG. 2 illustrates an exemplary communication method implemented in a source DU according to some embodiments of the present disclosure.

[0027] [Figure 6] FIG. 13 illustrates another exemplary communication method implemented in a source DU in accordance with some embodiments of the present disclosure.

[0028] [Figure 7] FIG. 2 illustrates an example communication method implemented in a CU according to some embodiments of the present disclosure.

[0029] [Figure 8] FIG. 13 illustrates another exemplary communication method implemented in a CU according to some embodiments of the present disclosure.

[0030] [Figure 9] FIG. 2 illustrates an exemplary communication method implemented in a target DU, according to some embodiments of the present disclosure.

[0031] [Figure 10] FIG. 1 is a schematic block diagram of an apparatus suitable for implementing embodiments of the present disclosure.

[0032] In the drawings, the same or similar reference numbers represent the same or similar elements. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0033] The principles of the present disclosure will now be described with reference to some embodiments. It should be understood that these embodiments are provided for illustrative purposes only, to assist those skilled in the art in understanding and implementing the present disclosure, and do not imply any limitations on the scope of the present disclosure. The disclosure described herein can be implemented in various ways different from those described below.

[0034] In the following description and claims, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains.

[0035] As used herein, the term "terminal device" refers to any device with wireless or wired communication capabilities. Examples of terminal devices include user equipment (UE), personal computers, desktops, mobile phones, mobile phones, smartphones, personal digital assistants (PDAs), portable computers, tablets, wearable devices, Internet of Things (IoT) devices, Ultra-reliable and Low Latency Communications (URLLC) devices, Internet of Everything (IoE) devices, machine type communication (MTC) devices, vehicle-mounted devices for V2X communications (where X means pedestrians, vehicles, or infrastructure / networks), devices for Integrated Access and Backhaul (IAB), spacecraft or aircraft in High Altitude Platforms (HAPs) including Unmanned Aircraft Systems (UASs) and Non-terrestrial networks (NTNs) including satellites, and Extended Reality (XR) including different types of reality such as Augmented Reality (AR), Mixed Reality (MR), and Virtual Reality (VR). Examples of such devices include, but are not limited to, Reality devices, unmanned aerial vehicles (UAVs), commonly known as drones, which are aircraft that do not require a human pilot, devices on high speed trains (HSTs), imaging devices such as digital cameras, sensors, gaming devices, music storage and playback devices, or Internet devices that enable wireless or wired Internet access and browsing.The "terminal equipment" may further have multicast / broadcast capabilities to support public safety, mission-critical, V2X applications, transparent IPv4 / IPv6 multicast distribution, IPTV, smart TV, wireless services, wireless software distribution, group communication, and IoT applications. It may also incorporate one or more Subscriber Identity Modules (SIMs), known as multi-SIM. The term "terminal equipment" may be used interchangeably with UE, mobile station, subscriber equipment, mobile terminal, user terminal, or wireless device.

[0036] The term "network device" refers to a device capable of providing or hosting a cell or coverage through which terminal devices can communicate. Examples of network devices include, but are not limited to, a Node B (NodeB or NB), an Evolved Node B (eNodeB or eNB), a next generation Node B (gNB), a transmission reception point (TRP), a remote radio unit (RRU), a radio head (RH), a remote radio head (RRH), an IAB node, a low power node such as a femto node, a pico node, a reconfigurable intelligent surface (RIS), etc.

[0037] The terminal device or network device may have the capability of artificial intelligence (AI) or machine learning. Generally, it includes a model trained from a large amount of data collected for a specific function and can be used to predict some information.

[0038] The terminal device or network device may function in multiple frequency ranges, e.g., FR1 (410 MHz-7125 MHz), FR2 (24.25 GHz-71 GHz), higher than 100 GHz, Terahertz (THz), etc. Furthermore, it can function in licensed / unlicensed / shared spectrum. The terminal device may have multiple connections with the network device in Multi-Radio Dual Connectivity (MR-DC) application scenarios. The terminal device or network device can function in full duplex, flexible duplex, and cross-division duplex modes.

[0039] Embodiments of the present disclosure may be implemented in test equipment, such as, for example, a signal generator, a signal analyzer, a spectrum analyzer, a network analyzer, a test terminal equipment, a test network equipment, a channel emulator, and the like.

[0040] In one embodiment, the terminal device may connect to a first network device and a second network device. One of the first network device and the second network device may be a master node, and the other may be a secondary node. The first network device and the second network device may use different radio access technologies (RATs). In one embodiment, the first network device may be a first RAT device, and the second network device may be a second RAT device. In one embodiment, the first RAT device is an eNB, and the second RAT device is a gNB. Information about the different RATs may be transmitted to the terminal device from at least one of the first network device or the second network device. In one embodiment, the first information may be transmitted to the terminal device from the first network device, and the second information may be transmitted to the terminal device from the second network device directly or via the first network device. In one embodiment, information about the configuration of the terminal device configured by the second network device may be transmitted from the second network device via the first network device. Information regarding the reconfiguration of the terminal device configured by the second network device may be transmitted from the second network device directly to the terminal device or via the first network device.

[0041] As used herein, the singular forms "a," "an," and "the" are intended to include the plural forms unless the context clearly indicates otherwise. The term "comprises" and variations thereof are intended to be open ended, meaning "including, but not limited to." The term "based on" is intended to mean "based at least in part on." The terms "one embodiment" and "embodiment" are intended to mean "at least one embodiment." The term "another embodiment" is intended to mean "at least one other embodiment." Terms such as "first," "second," and the like may refer to different objects or the same object. The following content may include other definitions, both explicit and implicit.

[0042] In some instances, values, processes or devices are referred to as "optimum," "lowest," "highest," "minimum," "maximum," etc. It will be understood that such descriptions are intended to indicate choices among multiple functional alternatives that may be used, and that such choices are not necessarily better, smaller, higher, or more preferred than other choices.

[0043] In the context of the present disclosure, the term "cell change or addition" may be used interchangeably with "reconfiguration with synchronization for a secondary cell group (SCG) or master cell group (MCG)". The term "PSCell" refers to an SpCell of an SCG, the term "PCell" refers to an SpCell of an MCG, and the term "SpCell" refers to a primary cell of an SCG or MCG. The term "SCell" refers to a secondary cell. The term "L1 / L2-based mobility" may be used interchangeably with "L1 / L2-based mobility procedure" or "lower layer signaling-based cell change or addition" or "L1 / L2-based handover". The term "lower layer signaling" may be used interchangeably with "L1 / L2 signaling". The term "RRC reconfiguration" may be used interchangeably with "RRC reconfiguration message". The term "data transmission" refers to the transmission and reception of data.

[0044] Nowadays, - configuration and maintenance of multiple candidate cells allowing rapid application of configurations to the candidate cells; - Dynamic switching mechanisms between candidate serving cells (including SpCells and SCells) for potential applicable scenarios based on L1 / L2 signaling; - L1 extensions for inter-cell beam management, including L1 measurements and reporting, and beam direction; - Timing advance (TA) management, - It is proposed to specify L1 / L2 based mobility mechanisms and procedures for reducing mobility latency, in terms of CU-DU interface signalling to support L1 / L2 mobility, if necessary.

[0045] The L1 / L2 based mobility procedure may be applied in the following scenarios: - Standalone, carrier aggregation (CA) and New Radio (NR) dual connectivity (DC) cases with serving cell change within one cell group (CG); - Intra-DU and intra-CU inter-DU cases (applicable to standalone and CA, no new RAN interfaces are foreseen), - both intra- and inter-frequency, - both frequency range 1 (FR1) and frequency range 2 (FR2), The source and target cells may be synchronized or asynchronous.

[0046] The embodiments of the present disclosure provide a CU-DU interface signaling solution to support L1 / L2 based mobility.

[0047] In one aspect, the embodiments of the present disclosure provide a solution for preparing a candidate cell for L1 / L2-based mobility in a CU-DU scenario. In another aspect, the embodiments of the present disclosure provide a solution for enabling a DU to be aware of the lower layer measurement configuration of other DUs. In yet another aspect, the embodiments of the present disclosure provide a solution for triggering L1 / L2-based mobility in a CU-DU scenario. Thus, a CU-DU interaction mechanism is defined for L1 / L2-based mobility.

[0048] The principles and embodiments of the present disclosure will now be described in detail with reference to the accompanying drawings.

[0049] Communication Network Example 1A is a schematic diagram illustrating an example communication network 100A in which embodiments of the present disclosure can be implemented. As shown in FIG. 1A, the communication network 100A may include a terminal device 110 and a plurality of network devices 120 and 130 (also referred to herein as network device 120 and network device 130 for convenience). The network devices 120 and 130 provide respective cells 121 and 131 to serve the terminal device.

[0050] It should be understood that the number of devices in FIG. 1A is given for illustrative purposes and does not imply any limitations to the present disclosure. Communications network 100A may include any suitable number of network devices and / or terminal devices suitable for implementing embodiments of the present disclosure. Furthermore, each of network devices 120 and 130 may provide more cells to terminal device 110.

[0051] As shown in FIG. 1A, terminal device 110 may communicate with network device 120 or 130 via a channel, such as a wireless communication channel. Communications in communication network 100A may conform to any suitable standard, including, but not limited to, Global System for Mobile Communications (GSM), Long Term Evolution (LTE), LTE-Evolution, LTE-Advanced (LTE-A), New Radio (NR), Wideband Code Division Multiple Access (WCDMA), Code Division Multiple Access (CDMA), GSM EDGE Radio Access Network (GERAN), Machine Type Communication (MTC), and the like. Embodiments of the present disclosure may be performed according to any generation of communication protocols now known or developed in the future. Examples of communication protocols include, but are not limited to, first generation (1G), second generation (2G), 2.5G, 2.75G, third generation (3G), fourth generation (4G), 4.5G, fifth generation (5G) communication protocols, 5.5G, 5G-Advanced networks, or sixth generation (6G) networks.

[0052] Communications in the direction from terminal device 110 to network device 120 or 130 are referred to as uplink (UL) communications, and communications in the opposite direction from network device 120 or 130 to terminal device 110 are referred to as downlink (DL) communications. Terminal device 110 may move between cells of network devices 120, 130, and possibly other network devices. In UL communications, terminal device 110 may transmit UL data and control information to network device 120 or 130 over a UL channel. In DL communications, network device 120 or 130 may transmit DL data and control information to terminal device 110 over a DL channel.

[0053] The communication in the communication network 100A may be performed according to the UP and CP protocol stacks. Generally speaking, for a communication device (e.g., a terminal device or a network device), there may be multiple entities of multiple network protocol layers in the protocol stack, and these entities may be configured to perform corresponding processes on data or signaling sent from and received by the communication device. FIG. 1B is a schematic diagram 100B showing network protocol layer entities that may be established for a UP protocol stack in an apparatus according to some embodiments of the present disclosure. In the following, for convenience, the communication between the terminal device 110 and the network device 120 is taken as an example for description. It should be understood that the following description is also suitable for the communication between the terminal device 110 and the network device 130.

[0054] In some embodiments, network devices 120 and 130 may be different network devices. In some embodiments, network devices 120 and 130 may be the same network device.

[0055] As shown in FIG. 1B, in the UP, each of the terminal device 110 and the network device 120 may include an L1 layer entity, i.e., a physical (PHY) layer entity (also referred to as a PHY entity), and one or more entities of higher layers (L2 layer and Layer 3 (L3) layer, or higher layers), including a media access control (MAC) layer entity (also referred to as a MAC entity), a radio link control (RLC) layer entity (also referred to as an RLC entity), a packet data convergence protocol (PDCP) layer entity (also referred to as a PDCP entity), and a service data application protocol (SDAP) layer entity (also referred to as an SDAP entity, which will be established in 5G and subsequent generation networks). In some cases, the PHY, MAC, RLC, PDCP, and SDAP entities are in a stack structure.

[0056] FIG. 1C is a schematic diagram 100C illustrating network protocol layer entities that may be established for a CP protocol stack in an apparatus according to some embodiments of the present disclosure. As shown in FIG. 1C, in a CP, each of the terminal device 110 and the network device 120 may include one or more entities of higher layers (L2 layer and L3 layer), including an L1 layer entity, i.e., a PHY layer entity (also referred to as a PHY entity), a MAC layer entity (also referred to as a MAC entity), an RLC layer entity (also referred to as an RLC entity), a PDCP layer entity (also referred to as a PDCP entity), and a radio resource control (RRC) layer entity (also referred to as an RRC entity). The RRC layer may further be referred to as an access stratum (AS) layer, and therefore the RRC entity may also be referred to as an AS entity. As shown in FIG. 1C, the terminal device 110 may further include a non-access stratum (NAS) layer entity (also referred to as a NAS entity). The NAS layer on the network side is located in a core network (CN, not shown) rather than in a network device. In some cases, these entities are in a stack structure.

[0057] In the context of this disclosure, L1 refers to the PHY layer, L2 refers to the MAC or RLC or PDCP or SDAP layer, and L3 refers to the RRC layer. In the context of this disclosure, L1 or L2 may be collectively referred to as lower layers, and L3 may be referred to as higher layers. Thus, L1 or L2 signaling may be referred to as lower layer signaling, and L3 signaling may be referred to as higher layer signaling.

[0058] Generally, communication channels are divided into logical channels, transmission channels, and physical channels. A physical channel is a channel through which a PHY layer actually transmits information. For example, the physical channel may include a physical uplink control channel (PUCCH), a physical uplink shared channel (PUSCH), a physical random-access channel (PRACH), a PDCCH, a physical downlink shared channel (PDSCH), and a physical broadcast channel (PBCH).

[0059] The transmission channel is a channel between the PHY layer and the MAC layer. For example, the transmission channel may include a broadcast channel (BCH), a downlink shared channel (DL-SCH), a paging channel (PCH), an uplink shared channel (UL-SCH), and a random access channel (RACH).

[0060] A logical channel is a channel between the MAC layer and the RLC layer. For example, the logical channel may include a dedicated control channel (DCCH), a common control channel (CCCH), a paging control channel (PCCH), a broadcast control channel (BCCH), and a dedicated traffic channel (DTCH).

[0061] Generally, a channel between the RRC layer and the PDCP layer is referred to as a radio bearer. The terminal device 110 may be configured with at least one data radio bearer (DRB) for carrying data plane data and at least one signaling radio bearer (SRB) for carrying control plane data. In the RRC layer, four types of SRBs may be defined: SRB0, SRB1, SRB2, and SRB3. SRB0 uses CCCH for establishing or re-establishing an RRC connection. SRB1 uses DCCH and is established when an RRC connection is established. SRB2 uses DCCH and is established during RRC re-configuration and after initial security activation. SRB3 uses DCCH and is established between the terminal device 110 and the SN when a dual connection is established.

[0062] 1D is a schematic diagram 100D illustrating a CU / DU architecture in which some embodiments of the present disclosure may be implemented. The CU / DU architecture may be established in a network device.

[0063] In the context of this disclosure, a CU (also referred to herein as gNB-CU) is a logical node that hosts the RRC, SDAP and PDCP protocols of a gNB or the RRC and PDCP protocols of an en-gNB, which controls the operation of one or more DUs (also referred to herein as gNB-DUs). The gNB-CU terminates the F1 interface connected to the gNB-DU. A DU is a logical node that hosts the RLC, MAC and PHY layers of a gNB or an en-gNB, the operation of which is partially controlled by the gNB-CU. One gNB-DU supports one or more cells. One cell is supported by only one gNB-DU. The gNB-DU terminates the F1 interface connected to the gNB-CU.

[0064] As shown in FIG. 1D, CU 141 is shown. It should be understood that more CUs may be included. CU 141 may communicate with multiple DUs. Here, two DUs 151 and 152 are shown for illustration. More DUs may be provided for the implementation of the embodiment of the present disclosure. Although not shown, CU 141 may be responsible for achieving the functions of an SDAP entity and a PDCP entity, and DU 151 or 152 may be responsible for achieving the functions of an RLC entity, a MAC entity, and a PHY entity.

[0065] DU 151 may provide cells 161, 162, and 163. DU 152 may provide cells 164, 165, and 166. It should be understood that this is just one example and more or less cells are possible. Terminal device 110 may communicate with any of these cells.

[0066] In some embodiments, the terminal device 110 may switch from one cell to another cell under the control of the same CU and the same DU. For example, the terminal device 110 may be handed over from one cell 161 to another cell 162. This is referred to as an intra-CU intra-DU serving cell change. In some embodiments, the terminal device 110 may switch from one cell to another cell under the control of the same CU and a different DU. For example, the terminal device 110 may be handed over from one cell 161 to another cell 164. In this case, a cell change occurs from one cell of the DU 151 to another cell of the DU 152. This is referred to as an intra-CU inter-DU serving cell change. In another example, the terminal device 110 may be handed over from a cell of one DU to a cell of another DU under the control of a different CU. In this case, a handover occurs from one CU to another CU. This is referred to as an inter-CU handover.

[0067] Network device 120 and network device 130 may correspond to one or two devices under the same CU. In some embodiments, the CU and the DU may be implemented in different devices. In some embodiments, the CU and the DU may be implemented in the same device. In some embodiments, different DUs may be implemented in different devices.

[0068] 1A , in some embodiments, terminal device 110 may be located within the coverage of cell 121 of network device 120, and terminal device 110 may communicate with network device 120 based on a network configuration. In this case, cell 121 may be referred to as a serving cell of terminal device 110.

[0069] In some embodiments, terminal device 110 may establish a dual connection (i.e., a simultaneous connection) with network device 120 and another network device (not shown). In some embodiments, network device 120 may function as a master node (MN). In these embodiments, terminal device 110 may communicate with network device 120 via a set of serving cells. The set of serving cells constitutes an MCG, and a primary cell in the MCG is referred to as a PCell. In some scenarios, the PCell may be changed from cell 121 to cell 131. This is referred to as a handover. In some embodiments, network device 120 may function as a secondary node (SN). In these embodiments, the set of serving cells provided by network device 120 forms an SCG, and a primary cell in the SCG is referred to as a PSCell. In some scenarios, the PSCell may be changed from cell 121 to cell 131. This is referred to as a PScell ​​change.

[0070] In some scenarios, terminal device 110 may receive L1 or L2 signaling indicating the addition, modification, or release of a serving cell from network device 120. Upon the addition, modification, or release of a serving cell, terminal device 110 may perform data transmission involving the addition, modification, or change of the serving cell. This procedure is referred to as L1 / L2-based mobility.

[0071] FIG. 1E is a schematic diagram illustrating a process 100E of L1 / L2-based mobility capable of implementing some embodiments of the present disclosure. For illustrative purposes, the process 100E is described with reference to FIG. 1A. The process 100E may involve a terminal device 110 and a network device 120 as shown in FIG. 1A. The network device 120 may be a MN or SN serving the terminal device 110. In this example, the network device 120 provides a serving cell for the terminal device 110. The network device 130 does not provide a serving cell for the terminal device 110.

[0072] 1E, the network device 120 may transmit an RRC reconfiguration including a set of configurations corresponding to a set of candidate cells enabling L1 / L2 based mobility to the terminal device 110 (170). The network device 120 may also transmit beam configurations (e.g., synchronization signal physical broadcast channel blocks (SSBs) or channel state information-reference signals (CSI-RS)) of the candidate cells for L1 measurements to the terminal device 110 (171).

[0073] The terminal device 110 may perform L1 measurements based on the configuration (172). If a condition is met by a beam, e.g., if the quality of the beam is above a threshold quality, the terminal device 110 may report an indication of the beam (e.g., an identity (ID) associated with the beam) to the network device 120 (173).

[0074] The network device 120 may send L1 / L2 signaling (e.g., downlink control information (DCI) or medium access control (MAC) control element (CE)) to the terminal device 110 (174) indicating that the TCI state for a cell among the candidate cells has been activated due to the cell change or addition.

[0075] Upon receiving the L1 / L2 signaling, the terminal device 110 may perform a cell change or addition (175). For example, a lower layer (e.g., PHY or MAC layer) of the terminal device 110 indicates cell change or addition information, such as an ID associated with a target cell, to the RRC layer of the terminal device 110. Upon receiving the indication, the RRC layer applies an RRC configuration corresponding to the target cell to perform the cell change or addition. The target cell may be a PCell, PSCell, or SCell of the terminal device 110. The terminal device 110 may start data transmission with the target cell using a preconfigured UE dedicated channel and an activated TCI state.

[0076] The embodiments of the present disclosure provide a CU-DU interface signaling solution for supporting L1 / L2 based mobility procedures, the details of which are described with reference to Figures 2 to 4C.

[0077] Example of CU-DU signaling implementation for candidate cell configuration FIG. 2 is a schematic diagram illustrating a process 200 of candidate cell configuration for L1 / L2-based mobility according to an embodiment of the present disclosure. For illustrative purposes, the process 200 is described with reference to FIG. 1D. The process 200 may involve the CU 141 and the DUs 151 and 152 as shown in FIG. 1D. In this example, the DU 151 serves the terminal device 110, and the DU 152 does not serve the terminal device 110. That is, the DU 151 serves as a source DU. The DU 152 serves as a candidate for the target DU (i.e., a candidate DU).

[0078] CU-initiated configuration for intra-DU scenarios As shown in Figure 2, the CU 141 may send a message (for convenience, also referred to as a first message herein) to a source DU (e.g., DU 151) to initialize, modify, or cancel a configuration for lower layer signaling-based cell change or addition (i.e., L1 / L2-based mobility) (210). For example, the first message may be a UE context modification request message. It should be understood that this is just one example and any other suitable message is also possible.

[0079] In some embodiments, the first message may include first L1 / L2-based mobility information (also referred to as information L1 / L2-based intra-DU mobility information). In some embodiments, the first L1 / L2-based mobility information may include an instruction of initialization, modification, or cancellation of the configuration for L1 / L2-based mobility. In other words, the instruction indicates whether the first message is related to initialization of L1 / L2-based mobility, modification of L1 / L2-based mobility, or cancellation of L1 / L2-based mobility. In some embodiments, the first message may include ID information of a set of candidate cells of the DU 151 for L1 / L2-based mobility. For example, the ID information may include a cell global ID (CGI). It should be understood that any other suitable ID information is also possible. In some embodiments, the first L1 / L2-based mobility information may include ID information of a set of candidate cells to be canceled for L1 / L2-based mobility. In some embodiments, the set of candidate cells may include a candidate cell. In some embodiments, the candidate cell may be a candidate SpCell. In some embodiments, the candidate cell may be a candidate SCell. In some embodiments, the set of candidate cells may include multiple candidate cells. In some embodiments, the set of candidate cells may include a set of candidate SpCells. In some embodiments, the set of candidate cells may include a set of candidate SCells. In some embodiments, the first L1 / L2 based mobility information includes a list of IDs of candidate cells to be cancelled. It should also be understood that the first message may include any other suitable information or combination of information.

[0080] Upon receiving the first message, the DU 151 may modify the context of the terminal device 110 (i.e., the UE context) (211). If the DU 151 successfully modifies the UE context, the DU 151 may send a positive response to the first message to the CU 141 (212). For example, the DU 151 may send a UE context modification response message to the CU 141. Of course, the positive response may also adopt any other suitable message.

[0081] In some embodiments, if the first message is for L1 / L2-based mobility initialization and includes ID information of a set of candidate cells of the DU 151 for L1 / L2-based mobility, the DU 151 may cause the ID information of the set of candidate cells of the DU 151 to be included in the positive response. In some alternative embodiments where the first message does not include ID information of a set of candidate cells of the DU 151 for L1 / L2-based mobility, the DU 151 may determine the set of candidate cells of the DU 151 by itself and send the ID information of the set of candidate cells of the DU 151 to the CU 141 in the positive response.

[0082] In some embodiments, if the first message relates to modifying L1 / L2 based mobility, the DU 151 may replace an existing prepared L1 / L2 based mobility identified by the ID of the terminal device 110 (e.g., gNB-DU UE F1AP ID) and the IDs of a set of candidate cells of the DU 151 for the L1 / L2 based mobility provided in the first message.

[0083] In some embodiments, if the first message is related to the cancellation of L1 / L2 based mobility, the DU 151 may assume that the CU 141 deletes all configurations and releases all pre-reserved resources for candidate cells associated with terminal device 110 related signaling identified by the terminal device 110 ID (e.g., gNB-CU UE F1AP ID and gNB-DU UE F1AP ID). In some embodiments, if the first message includes a list of IDs of candidate cells to be canceled, the DU 151 may assume that only the resources reserved for the cells identified by the list of IDs are released by the CU 141.

[0084] 2, if the DU 151 does not succeed in modifying the UE context, the DU 151 may send a negative response to the first message to the CU 141 (213). For example, the DU 151 may send a UE context modification failure message to the CU 141. Of course, this negative response may also adopt any other suitable message.

[0085] In some embodiments in which the first message includes ID information of a set of candidate cells of the DU 151 for L1 / L2-based mobility, the DU 151 may cause the ID information of the set of candidate cells of the DU 151 to be included in the negative response.

[0086] Thus, CU initiated configuration and management of L1 / L2 based mobility information is realized for intra-DU scenarios.

[0087] CU-initiated configuration for DU-to-DU scenarios 2, the CU 141 may send a message (220) to a candidate DU (e.g., DU 152) to initialize or modify a configuration for lower layer signaling-based cell change or addition (i.e., L1 / L2-based mobility) (also referred to herein as a third message for convenience). For example, the third message may be a UE context installation request message. It should be understood that this is just one example and any other suitable message is also possible.

[0088] In some embodiments, the third message may include second L1 / L2-based mobility information (also referred to as information L1 / L2-based inter-DU mobility information). In some embodiments, the second L1 / L2-based inter-DU mobility information may include an instruction for initializing or canceling the change of the configuration for L1 / L2-based mobility. In other words, the instruction indicates whether the third message is related to initializing or modifying the L1 / L2-based mobility. In some embodiments, the second L1 / L2-based inter-DU mobility information may include ID information of a set of candidate cells of the DU 152 for L1 / L2-based mobility. For example, the ID information may include a cell global ID (CGI). It should be understood that any other suitable ID information is also possible. In some embodiments, the second L1 / L2-based inter-DU mobility information may include ID information of the terminal device 110. For example, the ID information may include a target gNB-DU UE FlAP ID. It should be understood that any other suitable ID information is also possible. In some embodiments, the set of candidate cells may include a candidate cell. In some embodiments, the candidate cell may be a candidate SpCell, and in some embodiments, the candidate cell may be a candidate SCell. In some embodiments, the set of candidate cells may include multiple candidate cells. In some embodiments, the set of candidate cells may include a set of candidate SpCells. In some embodiments, the set of candidate cells may include a set of candidate SCells. It should also be understood that the third message may include any other suitable information or combination of information.

[0089] Upon receiving the third message, the DU 152 may establish a context (i.e., a UE context) of the terminal device 110 (221). If the DU 152 successfully establishes the UE context, the DU 152 may send a positive response to the third message to the CU 141 (222). For example, the DU 152 may send a UE context establishment response message to the CU 141. Of course, this positive response may also adopt any other suitable message.

[0090] In some embodiments, if the third message is for L1 / L2-based mobility initialization and includes ID information of a set of candidate cells of the DU 152 for L1 / L2-based mobility, the DU 152 may cause the ID information of the set of candidate cells of the DU 152 to be included in the positive response. In some alternative embodiments where the third message does not include ID information of a set of candidate cells of the DU 152 for L1 / L2-based mobility, the DU 152 may determine the set of candidate cells of the DU 152 by itself and send the ID information of the set of candidate cells of the DU 152 to the CU 141 in the positive response.

[0091] In some embodiments, if the third message relates to modifying L1 / L2 based mobility, the DU 152 may replace an existing prepared L1 / L2 based mobility identified by the ID information of the terminal device 110 (e.g., target gNB-DU UE F1AP ID) and the ID information of a set of candidate cells of the DU 152.

[0092] 2, if the DU 152 does not succeed in establishing the UE context, the DU 152 may send a negative response to the third message to the CU 141 (223). For example, the DU 151 may send a UE context installation failure message to the CU 141. Of course, this negative response may also adopt any other suitable message.

[0093] In some embodiments in which the third message includes ID information of a set of candidate cells of the DU 152 for L1 / L2-based mobility, the DU 152 may cause the ID information of the set of candidate cells of the DU 152 to be included in the negative response.

[0094] Thus, CU-initiated initialization and modification of L1 / L2-based mobility information is realized for inter-DU scenarios.

[0095] 2, the CU 141 may send a message (also referred to herein as a fourth message for convenience) to the candidate DU (e.g., DU 152) indicating the cancellation of the configuration for L1 / L2-based mobility (224). In some embodiments, the fourth message may be a UE context release command message. It should be understood that this is only one example and any other suitable message is possible. The DU 152 may send an acknowledgement message to the CU 141. In some embodiments, the acknowledgement message may be a UE context release complete message.

[0096] In some embodiments, the fourth message may include ID information of a set of candidate cells of the DU 152 to be cancelled for L1 / L2 based mobility. For example, the ID information may include a CGI. It should be understood that any other suitable ID information is also possible. In some embodiments, the set of candidate cells may include a candidate cell. In some embodiments, the candidate cell may be a candidate SpCell. In some embodiments, the candidate cell may be a candidate SCell. In some embodiments, the set of candidate cells may include multiple candidate cells. In some embodiments, the set of candidate cells may include a set of candidate SpCells. In some embodiments, the set of candidate cells may include a set of candidate SCells. It should also be understood that the fourth message may include any other suitable information or combination of information.

[0097] Upon receiving the fourth message, the DU 152 may consider (225) that the CU 141 is canceling only the L1 / L2-based mobility associated with the cells identified by the ID information of the set of candidate cells of the DU 152 to be canceled and associated with the terminal device-related signaling identified by the ID of the terminal device 110 (e.g., gNB-CU UE F1AP ID and gNB-DU UE F1APID).

[0098] Thus, CU initiated cancellation of L1 / L2 based mobility information is achieved for inter-DU scenarios.

[0099] Alternatively, cancellation of L1 / L2-based mobility information may also be initiated by the DU for inter-DU or intra-DU scenarios, which will be explained subsequently with reference to FIG.

[0100] 2, the DU 151 may send a message (also referred to herein as a second message for convenience) to the CU 141 requesting cancellation of the configuration for L1 / L2-based mobility (230). For example, the second message may be a UE context modification request message. It should be understood that this is only one example and any other suitable message is also possible. The DU 151 may send an acknowledgement message to the CU 141. In some embodiments, the acknowledgement may be a UE context modification acknowledgement message.

[0101] In some embodiments, the second message may include ID information of a set of candidate cells of the DU 151 to be cancelled for L1 / L2 based mobility. For example, the ID information may include a CGI. It should be understood that any other suitable ID information is also possible. In some embodiments, the set of candidate cells may include a candidate cell. In some embodiments, the candidate cell may be a candidate SpCell. In some embodiments, the candidate cell may be a candidate SCell. In some embodiments, the set of candidate cells may include multiple candidate cells. In some embodiments, the set of candidate cells may include a set of candidate SpCells. In some embodiments, the set of candidate cells may include a set of candidate SCells. It should also be understood that the second message may include any other suitable information or combination of information.

[0102] Upon receiving the second message, the CU 141 may consider (231) that only resources reserved for candidate cells associated with terminal device related signaling identified by the ID information of the set of candidate cells of the DU 151 to be canceled and identified by the ID of the terminal device 110 (e.g., gNB-CU UE F1AP ID and gNB-CU UE F1AP ID) are to be released by the DU 151.

[0103] Thus, DU initiated cancellation of L1 / L2 based mobility information is realized for intra-DU scenarios.

[0104] 2, the DU 152 may send a message (also referred to herein as a fifth message for convenience) to the CU 141 requesting cancellation of the configuration for L1 / L2-based mobility (232). For example, the fifth message may be a UE context release request message. It should be understood that this is only one example and any other suitable message is also possible.

[0105] In some embodiments, the fifth message may include ID information of a set of candidate cells of the DU 152 to be cancelled for L1 / L2 based mobility. For example, the ID information may include a CGI. It should be understood that any other suitable ID information is also possible. In some embodiments, the set of candidate cells may include a candidate cell. In some embodiments, the candidate cell may be a candidate SpCell. In some embodiments, the candidate cell may be a candidate SCell. In some embodiments, the set of candidate cells may include multiple candidate cells. In some embodiments, the set of candidate cells may include a set of candidate SpCells. In some embodiments, the set of candidate cells may include a set of candidate SCells. It should also be understood that the second message may include any other suitable information or combination of information.

[0106] Upon receiving the fifth message, the CU 141 may consider (233) that only resources reserved for candidate cells associated with terminal device related signaling identified by the ID information of the set of candidate cells of the DU 152 to be canceled and identified by the ID of the terminal device 110 (e.g., gNB-CU UE F1AP ID and gNB-CU UE F1AP ID) are to be released by the DU 152.

[0107] Thus, DU initiated cancellation of L1 / L2 based mobility information is realized for inter-DU scenarios.

[0108] Example of CU-DU signaling implementation for lower layer measurement configuration Conventionally, the L1 measurement and reporting configuration for a DU's serving cells is generated by the DU and is transparent to the CU. In the case of L1 / L2-based mobility, the UE is required to perform lower layer measurements on beams of non-serving cells belonging to multiple DUs and report the measurement results to the UE's current serving DU. However, it is still unclear how to enable the UE to perform beam measurements on candidate cells belonging to non-serving DUs.

[0109] In view of this, embodiments of the present disclosure provide a lower layer measurement configuration solution for L1 / L2 based mobility, which is described below in conjunction with FIG.

[0110] FIG. 3 is a schematic diagram illustrating a process 300 of lower layer measurement configuration for L1 / L2-based mobility according to an embodiment of the present disclosure. For illustrative purposes, the process 300 is described with reference to FIG. 1D. The process 300 may involve the CU 141 and the DUs 151 and 152 as shown in FIG. 1D. In this example, the DU 151 serves the terminal device 110, and the DU 152 does not serve the terminal device 110. That is, the DU 151 serves as a source DU. The DU 152 serves as a candidate for the target DU (i.e., a candidate DU).

[0111] CU transfer settings between DUs As shown in FIG. 3, in some embodiments, the DU 151 may transmit a configuration for lower layer measurement and reporting for a set of candidate cells of the DU 151 (also referred to herein as a first configuration for convenience) to the CU 141 (310).

[0112] For example, in case of intra-DU mobility, the DU 151 may send the L1 measurement and reporting configuration of the candidate cells of the DU 151 to the CU 141 in a UE context modification request response message. It should be understood that any other suitable message, existing or developed, is also possible.

[0113] Then, the CU 141 may transmit the first configuration to at least one candidate DU, such as the DU 152 (311). For example, the CU 141 may transmit the L1 measurement and reporting configuration of the DU 151 to the DU 152 via a UE context installation request message. It should be understood that any other suitable message, existing or developed, is also possible.

[0114] In some embodiments, a candidate DU (e.g., DU 152) may send a configuration (for convenience, also referred to herein as a second configuration) for lower layer measurement and reporting for the set of candidate cells of the DU 152 to the CU 141 (320).

[0115] For example, in case of inter-DU mobility, the DU 152 may send the L1 measurement and reporting configuration of the candidate cells of the DU 152 to the CU 141 in the UE context installation request response message. It should be understood that any other suitable message, existing or developed, is also possible.

[0116] Then, the CU 141 may transmit the second configuration to the source DU (e.g., DU 151) and other candidate DUs (321). For example, the CU 141 may transmit the L1 measurement and reporting configuration of the DU 152 to the DU 151 through a UE context modification request message. It should be understood that any other suitable message, existing or developed, is also possible. As another example, the CU 141 may transmit the L1 measurement and reporting configuration of the DU 152 to other candidate DUs through a UE context installation request message.

[0117] Thus, it is possible to enable L1 measurement and reporting configuration for candidate cells of non-serving DUs.

[0118] DU CU transmission information Alternatively, the CU may transmit to each DU information of the candidate cells of the other DUs, thereby enabling each DU to generate lower layer measurement and reporting configurations for the candidate cells of the other DUs, which is conveniently described below with continued reference to FIG.

[0119] 3, the CU 140 may send (330) information of a set of candidate cells of at least one candidate DU (e.g., DU 152) to the DU 151. For example, the CU 141 may send the information of the candidate cells in the DU 152 to the DU 151 in a UE context modification request message. It should be understood that any other suitable message, existing or developed, is also possible.

[0120] Based on the received information of the candidate cells in the DU 152, the DU 151 may generate a configuration (for convenience, also referred to as a third configuration in this specification) for lower layer measurement and reporting for the set of candidate cells of the at least one candidate DU (331). Then, the DU 151 may transmit the third configuration to the CU 141 (332).

[0121] 3, the CU 140 may also send (340) information of a set of candidate cells of the source DU (e.g., DU 151) and other candidate DUs to the DU 152. For example, the CU 141 may send the information of the candidate cells in the DU 151 to the DU 152 in a UE context installation request message. It should be understood that any other suitable message, existing or developed, is also possible.

[0122] Based on the received information of the candidate cells in the DU 151 and other candidate DUs, the DU 152 may generate a configuration (for convenience, also referred to as a fourth configuration in this specification) for lower layer measurement and reporting for a set of candidate cells of the DU 151 and other candidate DUs (341). Then, the DU 152 may transmit the fourth configuration to the CU 141 (342).

[0123] Thus, it is also possible to enable L1 measurement and reporting configuration for candidate cells of non-serving DUs.

[0124] Example of CU-DU signaling implementation for L1 / L2 based mobility implementation For a traditional handover (HO) procedure, the CU sends the target cell ID to the DU because the traditional HO procedure is based on L3 measurement reports and the CU receives the L3 measurement results from the UE. However, for L1 / L2-based mobility, it is the source DU that receives the L1 / L2 measurement reports. Then the question becomes which node decides about L1 / L2-based mobility and what information needs to be exchanged between nodes.

[0125] In view of this, embodiments of the present disclosure provide solutions for implementing L1 / L2-based mobility, which are described, for illustrative purposes, with reference to Figures 4A-4C.

[0126] Decision by CU FIG. 4A is a schematic diagram illustrating a process 400A for triggering L1 / L2-based mobility according to an embodiment of the present disclosure. For illustrative purposes, the process 400A is described with reference to FIG. 1D. The process 400A may involve the CU 141 and the DUs 151 and 152 as shown in FIG. 1D. In this example, the DU 151 serves the terminal device 110, and the DU 152 does not serve the terminal device 110. That is, the DU 151 serves as a source DU. The DU 152 serves as a candidate for the target DU (i.e., a candidate DU).

[0127] As shown in FIG. 4A, the terminal device 110 may send a lower layer measurement report to the DU 151 (410).

[0128] Upon receiving the lower layer measurement report, the DU 151 may transmit information (for convenience, also referred to herein as first information or auxiliary information) regarding at least one candidate cell for lower layer signaling-based cell change or addition (i.e., L1 / L2-based mobility) to the CU 141 (411).

[0129] In some embodiments, the auxiliary information may be transmitted by an F1 message. In some embodiments, the auxiliary information may include ID information of the at least one candidate cell. For example, the auxiliary information may include CGI of one or more proposed SpCells or SCells. In some embodiments, the auxiliary information may include reference signal (RS) or transmission configuration indicator (TCI) information of the at least one candidate cell. For example, the auxiliary information may include an index of an RS or a TCI state. In some embodiments, the RS may be an SSB. In some embodiments, the RS may be a CSI-RS. In some embodiments, the auxiliary information may include measurement results of the at least one candidate cell. For example, the auxiliary information may include reference signal receive power (RSRP) or other measurement results of the proposed candidate cell and other candidate cells. It should be understood that the auxiliary information may also include any other suitable information or combination of information.

[0130] Based on the aiding information, the CU 141 may determine a target cell (also referred to herein as a selected candidate cell) for L1 / L2-based mobility (412). Thus, the CU decides on a target cell for L1 / L2-based mobility.

[0131] Assume that the DU 152 serves as a target DU serving a target cell. In some embodiments for inter-DU mobility, the CU 141 may send an indication to the DU 152 indicating that L1 / L2 based mobility is triggered for the target cell of the DU 152 (413). In some embodiments, the indication may include ID information of the target cell. For example, the indication may include CGI of the target SpCell or SCell. In some embodiments, the indication may include RS or TCI information of the target cell. For example, the auxiliary information may include an index of the RS or TCI state. In some embodiments, the RS may be an SSB. In some embodiments, the RS may be a CSI-RS. Note that the indication may include any other suitable information or combination of information.

[0132] Upon receiving the indication, the DU 152 may send an acknowledgement to the CU 141 for the triggering of L1 / L2 based mobility (414). In some embodiments, the acknowledgement may include a dedicated random access (RA) configuration (also referred to as a contention-free RA configuration) for L1 / L2 based mobility. In some embodiments, the acknowledgement may include a timing advance (TA) configuration for the target cell, e.g., a TA value for the target cell. Note that the acknowledgement may include any other suitable information or combination of information.

[0133] The CU 141 may transmit information (also referred to herein as second information for convenience) about the target cell for L1 / L2-based mobility to the DU 151 (415). In some embodiments for intra-DU mobility, the second information may include at least one of ID information of the target cell, or RS or TCI information of the target cell. For example, the indication may include a CGI of the target SpCell or SCell. For example, the auxiliary information may include an index of the RS or TCI state. In some embodiments, the RS may be an SSB. In some embodiments, the RS may be a CSI-RS. In some embodiments for inter-DU mobility, the second information may further include at least one of a dedicated RA configuration for L1 / L2-based mobility, or a TA configuration for the target cell. Note that these are merely examples, and the second information may include any other suitable information or combination of information.

[0134] Based on the second information, the DU 151 may send lower layer signaling (ie, L1 / L2 signaling) to the terminal device 110 to trigger L1 / L2-based mobility (416).

[0135] Thus, the CU has overall control over L1 / L2 based mobility procedures.

[0136] Determined by source DU FIG. 4B is a schematic diagram illustrating a process 400B for triggering L1 / L2-based mobility according to an embodiment of the present disclosure. For illustrative purposes, the process 400B is described with reference to FIG. 1D. The process 400B may involve the CU 141 and the DUs 151 and 152 as shown in FIG. 1D. In this example, the DU 151 serves the terminal device 110, and the DU 152 does not serve the terminal device 110. That is, the DU 151 serves as a source DU. The DU 152 serves as a candidate for the target DU (i.e., a candidate DU).

[0137] As shown in FIG. 4B, the terminal device 110 may send a lower layer measurement report to the DU 151 (420).

[0138] Upon receiving the lower layer measurement report, the DU 151 may determine 412 a target cell (also referred to herein as a selected candidate cell) for L1 / L2-based mobility. Thus, the source DU decides on a target cell for L1 / L2-based mobility.

[0139] The DU 151 may transmit information indicating that L1 / L2-based mobility has been triggered for the target cell (for convenience, also referred to as third information in this specification) to the CU 141 (422). For example, the third information may be an access success message. Of course, other existing messages or newly defined messages are not excluded.

[0140] In some embodiments, the third information may be transmitted by an F1 message. For example, the F1 message may be an access success message or any other suitable message. In some embodiments, the third information may include ID information of the target cell. For example, the third information may include a CGI of the target cell, e.g., an SpCell or an SCell. In some embodiments, the third information may include RS or TCI information of the target cell. For example, the third information may include an index of an RS or TCI state. In some embodiments, the RS may be an SSB. In some embodiments, the RS may be a CSI-RS. It should be understood that the third information may also include any other suitable information or combination of information.

[0141] Assume that the DU 152 serves as a target DU serving a target cell. In some embodiments for inter-DU mobility, the CU 141 may send an indication to the DU 152 indicating that L1 / L2 based mobility is triggered for the target cell of the DU 152 (423). In some embodiments, the indication may include ID information of the target cell. For example, the third information may include a CGI of the target cell, e.g., an SpCell or an SCell. In some embodiments, the indication may include RS or TCI information of the target cell. For example, the third information may include an index of the RS or TCI state. In some embodiments, the RS may be an SSB. In some embodiments, the RS may be a CSI-RS. Note that the indication may include any other suitable information or combination of information.

[0142] Upon receiving the indication, the DU 152 may send an acknowledgement for the triggering of L1 / L2 based mobility to the CU 141 (424). In some embodiments, the acknowledgement may include a dedicated RA configuration for L1 / L2 based mobility. In some embodiments, the acknowledgement may include a TA configuration for the target cell, e.g., a TA value for the target cell. Note that the acknowledgement may include any other suitable information or combination of information.

[0143] The CU 141 may transmit information regarding the target cell for L1 / L2-based mobility (also referred to herein as fourth information for convenience) to the DU 151 (425). In some embodiments for inter-DU mobility, the fourth information may include at least one of a dedicated RA configuration for L1 / L2-based mobility or a TA configuration for the target cell. Note that these are merely examples, and the fourth information may include any other suitable information or combination of information.

[0144] The DU 151 may send lower layer signaling (i.e., L1 / L2 signaling) to the terminal device 110 to trigger L1 / L2-based mobility (426). In some embodiments for inter-DU mobility, the DU 151 may send lower layer signaling including the fourth information.

[0145] In this way, the DU may directly decide on the target cell and inform the CU of this decision, thus avoiding delays on the F1 interface due to message exchanges between the CU and the DU.

[0146] Decision by candidate DU FIG. 4C is a schematic diagram illustrating a process 400C for triggering L1 / L2-based mobility according to an embodiment of the present disclosure. For illustrative purposes, the process 400C is described with reference to FIG. 1D. The process 400C may involve the CU 141 and the DUs 151 and 152 as shown in FIG. 1D. In this example, the DU 151 serves the terminal device 110, and the DU 152 does not serve the terminal device 110. That is, the DU 151 serves as a source DU. The DU 152 serves as a candidate for the target DU (i.e., a candidate DU).

[0147] As shown in FIG. 4C, the terminal device 110 may send a lower layer measurement report to the DU 151 (430).

[0148] Upon receiving the lower layer measurement report, the DU 151 may transmit information (for convenience, also referred to as fifth information in this specification) regarding at least one candidate cell for lower layer signaling-based cell change or addition (i.e., L1 / L2-based mobility) to the CU 141 (431).

[0149] In some embodiments, the fifth information may be transmitted by an F1 message. In some embodiments, the fifth information may include ID information of the at least one candidate cell. For example, the fifth information may include CGI of one or more proposed SpCells or SCells. In some embodiments, the fifth information may include RS or TCI information of the at least one candidate cell. For example, the fifth information may include an index of an RS or TCI state. In some embodiments, the RS may be an SSB. In some embodiments, the RS may be a CSI-RS. In some embodiments, the fifth information may include measurement results of the at least one candidate cell. For example, the fifth information may include RSRP or other measurement results of the proposed candidate cell and other candidate cells. It should be understood that the fifth information may also include any other suitable information or combination of information.

[0150] The CU 141 may forward the fifth information to the DU 152 (432). The DU 152 may determine a target cell (also referred to herein as a selected candidate cell) for L1 / L2-based mobility based on the fifth information (433). Thus, the candidate DU decides on a target cell for L1 / L2-based mobility.

[0151] Assume that the DU 152 decides to trigger L1 / L2-based mobility on one of the candidate cells of the DU 152. In these embodiments, the DU 152 may transmit information about the target cell for L1 / L2-based mobility (also referred to herein as sixth information for convenience) to the CU 141 (434). In some embodiments, the sixth information may include ID information of the target cell. In some embodiments, the sixth information may include RS or TCI information of the target cell. In some embodiments, the RS may be an SSB. In some embodiments, the RS may be a CSI-RS. In some embodiments, the sixth information may include a dedicated RA configuration for L1 / L2-based mobility. In some embodiments, the sixth information may include a TA configuration for the target cell. Note that these are merely examples and the sixth information may include any other suitable information or combination of information.

[0152] The CU 141 may forward the sixth information to the DN 151 (435). Based on the sixth information, the DU 151 may send lower layer signaling (i.e., L1 / L2 signaling) to the terminal device 110 to trigger L1 / L2-based mobility (436).

[0153] Thus, the candidate DU may decide whether to trigger L1 / L2-based mobility based on the candidate DU's latest situation.

[0154] Example of the method Therefore, the embodiments of the present disclosure provide communication methods implemented in a terminal device and a network device, which are described below with reference to Figures 5 to 9.

[0155] FIG. 5 illustrates an exemplary communication method 500 implemented in a first DU as a source DU according to some embodiments of the present disclosure. For example, the method 500 may be performed in the DU 151 as shown in FIG. 1D. Hereinafter, the method 500 will be described with reference to FIG. 1D for illustrative purposes. It should be understood that the method 500 may include additional blocks not shown and / or omit some blocks shown, and the scope of the present disclosure is not limited in this respect. In this example, the DU 151 serves the terminal device 110, and the DU 152 does not serve the terminal device 110. That is, the DU 151 serves as a source DU. The DU 152 serves as a candidate for the target DU (i.e., a candidate DU).

[0156] In block 510, the DU 151 sends first information regarding at least one candidate cell for lower layer signaling-based cell change or addition to the CU 141. In some embodiments, the first information may include at least one of ID information of the at least one candidate cell, RS or TCI information of the at least one candidate cell, or measurement results of the at least one candidate cell.

[0157] In block 520, the DU 151 receives second information regarding a target cell for the lower layer signaling-based cell change or addition from the CU 141. In some embodiments, the second information may include at least one of the following: identity information of the target cell, RS or TCI information of the target cell, a dedicated RA configuration for the cell change or addition, or a TA configuration for the target cell.

[0158] In some embodiments, the DU 151 may receive a first message from the CU 141 indicating initialization, modification, or cancellation of the configuration for the lower layer signaling-based cell change or addition. If the context of the terminal device (e.g., the terminal device 110) is successfully modified based on the first message, the DU 151 may send a positive response to the first message. If the context of the terminal device 110 is not successfully modified based on the first message, the DU 151 may send a negative response to the first message.

[0159] In some embodiments, the first message may include at least one of: an instruction to initialize, modify or cancel configuration for the lower layer signaling based cell change or addition, ID information of a set of candidate cells of the DU 151 for the lower layer signaling based cell change or addition, or ID information of a set of candidate cells to be canceled for the lower layer signaling based cell change or addition.

[0160] In some embodiments where the first message indicates the initialization of the configuration, the DU 151 may determine a set of candidate cells of the DU 151 for the lower layer signaling-based cell change or addition, and send ID information of the set of candidate cells of the DU 151 to the CU in the positive response.

[0161] In some embodiments, the DU 151 may send a second message to the CU 141 to request cancellation of the configuration for the lower layer signaling based cell change or addition.

[0162] In some embodiments, DU 151 may send to CU 141 a first configuration for lower layer measurement and reporting for a set of candidate cells of a first DU and receive from CU 141 a second configuration for lower layer measurement and reporting for a set of candidate cells of at least one candidate DU.

[0163] In some embodiments, the DU 151 may receive information of a set of candidate cells of at least one candidate DU from the CU 141, and generate a third configuration for lower layer measurement and reporting for the set of candidate cells of the at least one candidate DU. Then, the DU 151 may send the third configuration to the CU 141.

[0164] According to the method 500, the DU may provide assistance information to the CU to help the CU control L1 / L2 based mobility procedures.

[0165] FIG. 6 illustrates another exemplary communication method 600 implemented in a first DU as a source DU according to some embodiments of the present disclosure. For example, the method 600 may be performed in the DU 151 as shown in FIG. 1D. Hereinafter, the method 600 will be described with reference to FIG. 1D for illustrative purposes. It should be understood that the method 600 may include additional blocks not shown and / or omit some blocks shown, and the scope of the present disclosure is not limited in this respect. In this example, the DU 151 serves the terminal device 110, and the DU 152 does not serve the terminal device 110. That is, the DU 151 serves as a source DU. The DU 152 serves as a candidate for the target DU (i.e., a candidate DU).

[0166] In block 610, the DU 151 determines a target cell for lower layer signaling based cell change or addition.

[0167] In block 620, the DU 151 sends third information to the CU 141, indicating that the lower layer signaling-based cell change or add has been triggered for the target cell.

[0168] In some embodiments, the third information may include at least one of: ID information of the target cell, or RS or TCI information of the target cell.

[0169] In some embodiments, the DU 151 may receive fourth information regarding a target cell for the lower layer signaling-based cell change or add from the CU 141. In some embodiments, the fourth information may include at least one of a dedicated RA configuration for the lower layer signaling-based cell change or add, or a TA configuration for the target cell.

[0170] In some embodiments, the DU 151 may receive a first message from the CU 141 indicating initialization, modification, or cancellation of the configuration for the lower layer signaling-based cell change or addition. If the context of the terminal device (e.g., the terminal device 110) is successfully modified based on the first message, the DU 151 may send a positive response to the first message. If the context of the terminal device 110 is not successfully modified based on the first message, the DU 151 may send a negative response to the first message.

[0171] In some embodiments, the first message may include at least one of: an instruction to initialize, modify or cancel configuration for the lower layer signaling based cell change or addition, ID information of a set of candidate cells of the DU 151 for the lower layer signaling based cell change or addition, or ID information of a set of candidate cells to be canceled for the lower layer signaling based cell change or addition.

[0172] In some embodiments where the first message indicates the initialization of the configuration, the DU 151 may determine a set of candidate cells of the DU 151 for the lower layer signaling-based cell change or addition, and send ID information of the set of candidate cells of the DU 151 to the CU in the positive response.

[0173] In some embodiments, the DU 151 may send a second message to the CU 141 to request cancellation of the configuration for the lower layer signaling based cell change or addition.

[0174] In some embodiments, DU 151 may send to CU 141 a first configuration for lower layer measurement and reporting for a set of candidate cells of a first DU and receive from CU 141 a second configuration for lower layer measurement and reporting for a set of candidate cells of at least one candidate DU.

[0175] In some embodiments, the DU 151 may receive information of a set of candidate cells of at least one candidate DU from the CU 141, and generate a third configuration for lower layer measurement and reporting for the set of candidate cells of the at least one candidate DU. Then, the DU 151 may send the third configuration to the CU 141.

[0176] According to the method 600, the DU may directly decide on the target cell and inform the CU of the decision, thus avoiding the delay on the F1 interface due to message exchange between the CU and the DU.

[0177] FIG. 7 illustrates an exemplary communication method 700 implemented in a CU according to some embodiments of the present disclosure. For example, the method 700 may be executed in the CU 141 as shown in FIG. 1D. Hereinafter, the method 700 will be described with reference to FIG. 1D for illustrative purposes. It should be understood that the method 700 may include additional blocks not shown and / or omit some blocks shown, and the scope of the present disclosure is not limited in this respect. In this example, the DU 151 serves the terminal device 110, and the DU 152 does not serve the terminal device 110. That is, the DU 151 serves as a source DU. The DU 152 serves as a candidate for the target DU (i.e., a candidate DU).

[0178] In block 710, the CU 141 receives, from a source DU (eg, DU 151), first information regarding at least one candidate cell for lower layer signaling-based cell change or addition.

[0179] In some embodiments, the first information may include at least one of ID information of the at least one candidate cell, RS or TCI information of the at least one candidate cell, or measurement results of the at least one candidate cell.

[0180] In block 720, CU 141 determines a target cell for the lower layer signaling-based cell change or addition based on the first information.

[0181] In block 730, the CU 141 sends, to the DU 151, second information regarding the target cell for the lower layer signaling based cell change or addition.

[0182] In some embodiments, the second information may include at least one of ID information of the target cell, RS or TCI information of the target cell, dedicated RA settings for cell change or addition, or TA settings for the target cell.

[0183] In some embodiments in which the target cell is associated with a second DU (e.g., DU 152), CU 141 may send an indication to DU 152 indicating that the cell change or addition is triggered for the target cell, and receive an acknowledgement of the trigger from DU 152.

[0184] In some embodiments, the indication may include at least one of the following: identity of the target cell, or RS or TCI information of the target cell. In some embodiments, the acknowledgement may include at least one of a dedicated RA configuration for the cell change or addition, or a TA configuration for the target cell.

[0185] In some embodiments, the CU 141 may send a first message to the DU 151 indicating initialization, modification, or cancellation of the configuration for the lower layer signaling-based cell change or addition. In some embodiments where the context of a terminal device (e.g., terminal device 110) is successfully modified based on the first message, the CU 141 may receive a positive response to the first message from the DU 151. In some embodiments where the context of the terminal device 110 is not successfully modified based on the first message, the CU 141 may receive a negative response to the first message from the first DU.

[0186] In some embodiments where the first message indicates the initialization of the configuration, the CU 141 may receive in the positive response ID information of a set of candidate cells of the DU 151. In some embodiments, the first message may include at least one of an instruction to initialize, modify or cancel the configuration for the lower layer signaling based cell change or addition, ID information of a set of candidate cells of the DU 151 for the lower layer signaling based cell change or addition, ID information of a set of candidate cells to be canceled for the lower layer signaling based cell change or addition.

[0187] In some embodiments in which the target cell is associated with a second DU (e.g., DU 152), CU 141 may send a third message to DU 152 indicating initialization or modification of a configuration for the lower layer signaling-based cell change or addition, and receive a positive response to the second message from DU 152 if the context of the terminal device is successfully established, and a negative response to the second message from DU 152 if the context of the terminal device is not successfully established.

[0188] In some embodiments where the third message indicates the initialization of the configuration, CU 141 may receive ID information of a set of candidate cells of the second DU in the positive response.

[0189] In some embodiments, the third message may include at least one of an instruction to initialize, modify or cancel the configuration for the lower layer signaling-based cell change or addition, ID information of the terminal device, or identification information of a set of candidate cells for the DU 152.

[0190] In some embodiments where the target cell is associated with the DU 152, the CU 141 may send a fourth message to the second DU indicating cancellation of the configuration for the lower layer signaling-based cell change or addition.

[0191] In some embodiments, the CU 141 may receive a second message from the DU 151 to request cancellation of the configuration for the lower layer signaling based cell change or addition.

[0192] In some embodiments where the target cell is associated with the DU 152, the CU 141 may receive a fifth message from the DU 152 to request cancellation of the configuration for the lower layer signaling-based cell change or addition.

[0193] In some embodiments, the CU 141 may receive, from the DU 151, a first configuration for lower layer measurement and reporting for a set of candidate cells of the DU 151, and transmit the first configuration to at least one candidate DU.

[0194] In some embodiments, CU 141 may receive from at least one candidate DU a second configuration for lower layer measurement and reporting for a set of candidate cells of the at least one candidate DU and transmit the second configuration to DU 151.

[0195] In some embodiments, CU 141 may send information of a set of candidate cells of at least one candidate DU to DU 151, and receive a third configuration for lower layer measurement and reporting for the set of candidate cells of the at least one candidate DU from DU 151.

[0196] In some embodiments, the CU 141 may send information of a set of candidate cells of the DU 151 to at least one candidate DU, and receive a fourth configuration for lower layer measurement and reporting for the set of candidate cells of the DU 151 from the at least one candidate DU.

[0197] The method 700 allows the CU to have global control over L1 / L2 based mobility.

[0198] FIG. 8 illustrates another exemplary communication method 800 implemented in a CU according to some embodiments of the present disclosure. For example, the method 800 may be executed in the CU 141 as shown in FIG. 1D. Hereinafter, the method 800 will be described with reference to FIG. 1D for illustrative purposes. It should be understood that the method 800 may include additional blocks not shown and / or omit some blocks shown, and the scope of the present disclosure is not limited in this respect. In this example, the DU 151 serves the terminal device 110, and the DU 152 does not serve the terminal device 110. That is, the DU 151 serves as a source DU. The DU 152 serves as a candidate for the target DU (i.e., a candidate DU).

[0199] In block 810, the CU 141 receives third information from a source DU (eg, DU 151) indicating that a lower layer signaling-based cell change or addition has been triggered for the target cell.

[0200] In some embodiments where the target cell is associated with a second DU (e.g., DU 152), the CU 141 may send an indication to the DU 152 indicating that the lower layer signaling-based cell change or addition is triggered for the target cell. The CU 141 may receive an acknowledgement for the trigger from the DU 152, including fourth information regarding the target cell for the lower layer signaling-based cell change or addition, and send the fourth information to the DU 151.

[0201] In some embodiments, the indication may include at least one of the following: an identity of the target cell, or RS or TCI information of the target cell. In some embodiments, the acknowledgement may include at least one of a dedicated RA configuration for the lower layer signaling based cell change or addition, or a TA configuration for the target cell.

[0202] In some embodiments, the CU 141 may send a first message to the DU 151 indicating initialization, modification, or cancellation of the configuration for the lower layer signaling-based cell change or addition. In some embodiments where the context of a terminal device (e.g., terminal device 110) is successfully modified based on the first message, the CU 141 may receive a positive response to the first message from the DU 151. In some embodiments where the context of the terminal device 110 is not successfully modified based on the first message, the CU 141 may receive a negative response to the first message from the first DU.

[0203] In some embodiments where the first message indicates the initialization of the configuration, the CU 141 may receive in the positive response ID information of a set of candidate cells of the DU 151. In some embodiments, the first message may include at least one of an instruction to initialize, modify or cancel the configuration for the lower layer signaling based cell change or addition, ID information of a set of candidate cells of the DU 151 for the lower layer signaling based cell change or addition, ID information of a set of candidate cells to be canceled for the lower layer signaling based cell change or addition.

[0204] In some embodiments in which the target cell is associated with a second DU (e.g., DU 152), CU 141 may send a third message to DU 152 indicating initialization or modification of a configuration for the lower layer signaling-based cell change or addition, and receive a positive response to the second message from DU 152 if the context of the terminal device is successfully established, and a negative response to the second message from DU 152 if the context of the terminal device is not successfully established.

[0205] In some embodiments where the third message indicates the initialization of the configuration, CU 141 may receive ID information of a set of candidate cells of the second DU in the positive response.

[0206] In some embodiments, the third message may include at least one of an instruction to initialize, modify or cancel the configuration for the lower layer signaling-based cell change or addition, ID information of the terminal device, or identification information of a set of candidate cells for the DU 152.

[0207] In some embodiments where the target cell is associated with the DU 152, the CU 141 may send a fourth message to the second DU indicating cancellation of the configuration for the lower layer signaling-based cell change or addition.

[0208] In some embodiments, the CU 141 may receive a second message from the DU 151 to request cancellation of the configuration for the lower layer signaling based cell change or addition.

[0209] In some embodiments where the target cell is associated with the DU 152, the CU 141 may receive a fifth message from the DU 152 to request cancellation of the configuration for the lower layer signaling-based cell change or addition.

[0210] In some embodiments, the CU 141 may receive, from the DU 151, a first configuration for lower layer measurement and reporting for a set of candidate cells of the DU 151, and transmit the first configuration to at least one candidate DU.

[0211] In some embodiments, CU 141 may receive from at least one candidate DU a second configuration for lower layer measurement and reporting for a set of candidate cells of the at least one candidate DU and transmit the second configuration to DU 151.

[0212] In some embodiments, CU 141 may send information of a set of candidate cells of at least one candidate DU to DU 151, and receive a third configuration for lower layer measurement and reporting for the set of candidate cells of the at least one candidate DU from DU 151.

[0213] In some embodiments, the CU 141 may send information of a set of candidate cells of the DU 151 to at least one candidate DU, and receive a fourth configuration for lower layer measurement and reporting for the set of candidate cells of the DU 151 from the at least one candidate DU.

[0214] The method 800 allows for defining CU-DU interactions for L1 / L2 based mobility.

[0215] FIG. 9 illustrates an exemplary communication method 900 implemented in a second DU as a target DU according to some embodiments of the present disclosure. For example, the method 900 may be performed in the DU 152 as shown in FIG. 1D. Hereinafter, the method 900 will be described with reference to FIG. 1D for illustrative purposes. It should be understood that the method 900 may include additional blocks not shown and / or omit some blocks shown, and the scope of the present disclosure is not limited in this respect. In this example, the DU 151 serves the terminal device 110, and the DU 152 does not serve the terminal device 110. That is, the DU 151 serves as a source DU. The DU 152 serves as a candidate for the target DU (i.e., a candidate DU).

[0216] In block 910, the DU 152 receives an indication from the CU 141 indicating that a lower layer signaling based cell change or addition is triggered for a target cell associated with the DU 152. In some embodiments, the indication may include at least one of the following: ID information of the target cell, or RS or TCI information of the target cell.

[0217] In block 920, the DU 152 sends an acknowledgement for the trigger to the CU 141. In some embodiments, the acknowledgement may include at least one of a dedicated RA configuration for the cell change or addition, or a TA configuration for the target cell.

[0218] In some embodiments, DU 152 may receive a third message from CU 141 indicating initialization or modification of settings for the lower layer signaling-based cell change or addition, and may send a positive response to the second message to CU 141 if the context of a terminal device (e.g., terminal device 110) is successfully established, and may send a negative response to the second message to CU 141 if the context of the terminal device is not successfully established.

[0219] In some embodiments where the third message indicates the initialization of the configuration, the DU 152 may send ID information of its set of candidate cells in the positive response.

[0220] In some embodiments, the third message may include at least one of an instruction to initialize, modify or cancel the configuration for the lower layer signaling-based cell change or addition, ID information of the terminal device 110, or ID information of a set of candidate cells of the DU 152.

[0221] In some embodiments, the DU 152 may receive a fourth message from the CU 141 indicating cancellation of the configuration for the lower layer signaling based cell change or addition.

[0222] In some embodiments, the DU 152 may send a fifth message to the CU 141 to request cancellation of the configuration for the lower layer signaling based cell change or addition.

[0223] In some embodiments, DU 152 may send to CU 141 configuration for lower layer measurement and reporting for a set of candidate cells of the second DU and receive from CU 141 configuration for lower layer measurement and reporting for a set of candidate cells of the first DU.

[0224] In some embodiments, the DU 152 may receive information of a set of candidate cells of a first DU (e.g., DU 151) from the CU 141, generate a fifth configuration for lower layer measurement and reporting for the set of candidate cells of the DU 151, and send the fifth configuration to the CU 141.

[0225] The method 900 allows for defining CU-DU interactions for L1 / L2 based mobility.

[0226] It should be noted that the operations of methods 500-900 are similar to those described in connection with FIGS. 2-4C, and therefore, for the sake of brevity, other redundant details will not be described here.

[0227] Examples of equipment and devices 10 is a schematic block diagram of an apparatus 1000 suitable for implementing an embodiment of the present disclosure. The apparatus 1000 may be regarded as another exemplary implementation of the CU 141 and the DUs 151 and 152 shown in FIG. 1D. Thus, the apparatus 1000 may be implemented in the CU 141 and the DUs 151 and 152, or at least as a part thereof.

[0228] As shown, the apparatus 1000 comprises a processor 1010, a memory 1020 coupled to the processor 1010, a suitable transmitter (TX) and receiver (RX) 1040 coupled to the processor 1010, and a communication interface coupled to the TX / RX 1040. The memory 1020 stores at least a portion of a program 1030. The TX / RX 1040 is used for bidirectional communication. The TX / RX 1040 has at least one antenna to facilitate communication, although the access nodes referred to herein may in practice have multiple antennas. The communication interface may represent any interface required for communication with other network elements, such as the X2 interface for bidirectional communication between eNB / gNB, the S1 / NG interface for communication between a Mobility Management Entity (MME) / Access and Mobility Management Function (AMF) / SGW / UPF and a gNB / eNB, the Un interface for communication between a gNB / eNB and a relay node (RN), and the Uu interface for communication between a gNB / eNB and a terminal device.

[0229] The program 1030 is assumed to include program instructions that, when executed by the associated processor 1010, enable the device 1000 to operate according to embodiments of the present disclosure, as described herein with reference to Figures 2-9. The embodiments of the present disclosure may be implemented by computer software executable by the processor 1010 of the device 1000, or by hardware, or by a combination of software and hardware. The processor 1010 may be configured to implement various embodiments of the present disclosure. Furthermore, the combination of the processor 1010 and the memory 1020 may form a processing means 1050 suitable for implementing various embodiments of the present disclosure.

[0230] The memory 1020 may be of any type suitable for a local technology network and may be implemented using any suitable data storage technology, such as, by way of non-limiting example, non-transitory computer-readable storage media, semiconductor-based memory devices, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory. Although only one memory 1020 is shown in the device 1000, there may be several physically different memory modules in the device 1000. The processor 1010 may be of any type suitable for a local technology network and may include, by way of non-limiting example, one or more of a general purpose computer, a special purpose computer, a microprocessor, a digital signal processor (DSP) and a processor based on a multi-core processor architecture. The device 1000 may have multiple processors, for example application specific integrated circuit chips time-slaved to a clock that synchronizes the main processor.

[0231] In some embodiments, the first DU comprises a circuit configured to send, to a CU, first information regarding at least one candidate cell for a lower layer signaling based cell change or addition, and to receive, from the CU, second information regarding a target cell for the lower layer signaling based cell change or addition.

[0232] In some embodiments, the first DU comprises a circuit configured to determine a target cell for a lower layer signaling-based cell change or addition and to send third information to a CU indicating that the lower layer signaling-based cell change or addition has been triggered for the target cell.

[0233] In some embodiments, a CU comprises circuitry configured to receive, from a first DU, first information regarding at least one candidate cell for a lower layer signaling-based cell change or addition, determine a target cell for the lower layer signaling-based cell change or addition based on the first information, and send, to the first DU, second information regarding the target cell for the lower layer signaling-based cell change or addition.

[0234] In some embodiments, the CU comprises a circuit, the circuit configured to receive third information from the first DU indicating that a cell change or addition based on lower layer signaling has been triggered for the target cell.

[0235] In some embodiments, the second DU comprises a circuit configured to receive an indication from a CU indicating that a lower layer signaling-based cell change or addition is triggered for a target cell associated with the second DU, and to send an acknowledgment of the trigger to the CU.

[0236] The term "circuitry" as used herein may refer to hardware circuits and / or a combination of hardware circuits and software. For example, a circuit may be a combination of analog and / or digital hardware circuits and software / firmware. As a further example, a circuit may be any portion of a hardware processor with software, such as a digital signal processor, software, and memory that work together to perform various functions on a device, such as a terminal device or a network device. In yet another example, a circuit may be a hardware circuit and / or processor, such as a microprocessor or a portion of a microprocessor, that requires software / firmware for operation, but the software may not be present when not required for operation. As used herein, the term circuitry also encompasses merely a hardware circuit or processor, or a portion of a hardware circuit or processor, and its (or their) accompanying software and / or firmware implementations.

[0237] In summary, the embodiments of the present disclosure can provide the following solutions: Article 1 1. A method of communication comprising: Sending, in a first distributed unit (DU), to a central unit (CU), first information about at least one candidate cell for lower layer signaling-based cell change or addition; receiving, from the CU, second information regarding a target cell for the lower layer signaling based cell change or addition; The method includes: Article 2 The first information is an identity of the at least one candidate cell; Reference signal (RS) or transmission configuration indicator (TCI) information of the at least one candidate cell; or Measurement results of the at least one candidate cell; The method according to claim 1, comprising at least one of the following: Article 3 The second information is An identity of the target cell; Reference signal (RS) or transmission configuration indicator (TCI) information of the target cell; a dedicated random access configuration for the cell change or addition; or Setting a timing advance for the target cell; The method according to claim 1, comprising at least one of the following: Article 4 1. A method of communication comprising: Determining a target cell for lower layer signaling-based cell change or addition in a first distributed unit (DU); sending third information to a central unit (CU), indicating that the lower layer signaling based cell change or addition has been triggered for the target cell; and The method includes: Article 5 The third information is the identity of the target cell; or Reference signal (RS) or transmission configuration indicator (TCI) information of the target cell; The method according to claim 4, comprising at least one of the following: Article 6 receiving, from the CU, fourth information regarding the target cell for the lower layer signaling based cell change or addition; The method according to claim 4, further comprising: Article 7 The fourth information is a dedicated random access configuration for the lower layer signaling based cell change or addition; or setting a timing advance for the target cell; The method according to claim 6, comprising at least one of the following: Article 8 receiving a first message from the CU indicating initialization, modification, or cancellation of a configuration for the lower layer signaling-based cell change or addition; sending a positive response to the first message in response to a determination that a context of the terminal device has been successfully modified based on the first message; sending a negative response to the first message in response to a determination that the context of the terminal device was not successfully modified based on the first message; The method according to Article 1 or Article 4, further comprising: Article 9 The first message comprises: an instruction to initialize, modify or cancel the configuration for said lower layer signaling based cell change or addition; Identities of a set of candidate cells of the first DU for the lower layer signaling based cell change or addition; or Identities of a set of candidate cells to be cancelled for the lower layer signalling based cell change or addition; The method according to claim 8, comprising at least one of the following: Article 10 the first message indicating the initialization of the configuration, and sending the positive response determining a set of candidate cells of the first DU for the lower layer signaling based cell change or addition; transmitting, to the CU, in the positive response, identities of the set of candidate cells of the first DU; The methods described in Article 8, including: Article 11 sending a second message to the CU to request cancellation of the configuration for the lower layer signaling based cell change or addition; The method according to Article 1 or Article 4, further comprising: Article 12 Sending to the CU a first configuration for lower layer measurement and reporting for a set of candidate cells of the first DU; receiving, from the CU, a second configuration for lower layer measurement and reporting for a set of candidate cells of at least one candidate DU; The method according to Article 1 or Article 4, further comprising: Article 13 receiving information of a set of candidate cells of at least one candidate DU from the CU; generating a third configuration for lower layer measurement and reporting for the set of candidate cells of the at least one candidate DU; sending the third configuration to the CU; The method according to Article 1 or Article 4, further comprising: Article 14 1. A method of communication comprising: Receiving, in a central unit (CU), from a first distributed unit (DU), first information regarding at least one candidate cell for a lower layer signaling-based cell change or addition; determining a target cell for the lower layer signaling based cell change or addition based on the first information; transmitting, to the first DU, second information regarding a target cell for the lower layer signaling based cell change or addition; The method includes: Article 15 The first information is an identity of the at least one candidate cell; Reference signal (RS) or transmission configuration indicator (TCI) information of the at least one candidate cell; or Measurement results of the at least one candidate cell; The method according to claim 14, comprising at least one of the following: Article 16 The second information is An identity of the target cell; Reference signal (RS) or transmission configuration indicator (TCI) information of the target cell; a dedicated random access configuration for the cell change or addition; or setting a timing advance for the target cell; The method according to claim 14, comprising at least one of the following: Article 17 The target cell is associated with a second DU, and the method includes: sending an indication to the second DU indicating that the cell change or addition is triggered for the target cell; receiving an acknowledgement for the trigger from the second DU; The method according to clause 14, further comprising: Article 18 The instructions include: the identity of the target cell; or Reference signal (RS) or transmission configuration indicator (TCI) information of the target cell; The method according to claim 17, comprising at least one of the following: Article 19 The acknowledgement response may include: a dedicated random access configuration for the cell change or addition; or setting a timing advance for the target cell; The method according to claim 17, comprising at least one of the following: Article 20 1. A method of communication comprising: receiving, at a central unit (CU), from a first distributed unit (DU), third information indicating that a lower layer signaling-based cell change or addition has been triggered for the target cell; The method includes: Article 21 The target cell is associated with a second DU, and the method includes: sending an indication to the second DU indicating that the lower layer signaling based cell change or addition is triggered for the target cell; receiving an acknowledgement for the trigger from the second DU, the acknowledgement including fourth information about the target cell for the lower layer signaling based cell change or addition; Sending the fourth information to the first DU; The method according to clause 20, further comprising: Article 22 The instructions include: the identity of the target cell; or Reference signal (RS) or transmission configuration indicator (TCI) information of the target cell; The method according to claim 21, comprising at least one of the following: Article 23 The acknowledgement response may include: a dedicated random access configuration for the lower layer signaling based cell change or addition; or setting a timing advance for the target cell; The method according to claim 21, comprising at least one of the following: Article 24 Sending a first message to the first DU, indicating initialization, modification, or cancellation of the lower layer signaling-based cell change or addition configuration; receiving a positive response to the first message from the first DU if a context of a terminal device is successfully modified based on the first message; receiving a negative response to the first message from the first DU if the context of the terminal device is not successfully modified based on the first message; The method according to Article 14 or Article 20, further comprising: Article 25 The first message indicates the initialization of the configuration, and receiving the positive response receiving, in the positive response, identities of a set of candidate cells for the first DU; The method described in Article 24, including: Article 26 The first message comprises: an instruction to initialize, modify or cancel the configuration for said lower layer signaling based cell change or addition; Identities of a set of candidate cells of the first DU for the lower layer signaling based cell change or addition; or Identities of a set of candidate cells to be cancelled for the lower layer signalling based cell change or addition; The method according to claim 24, comprising at least one of the following: Article 27 The target cell is associated with a second DU, and the method includes: sending a third message to the second DU, the third message indicating an initialization or modification of a configuration for the lower layer signaling-based cell change or addition; receiving a positive response to the second message from the second DU if a terminal device context is successfully established; receiving a negative response to the second message from the second DU if the context of the terminal device is not successfully established; The method according to Article 14 or Article 20, further comprising: Article 28 the third message indicating the initialization of the configuration, and receiving the positive response receiving, in the positive response, identities of a set of candidate cells for the second DU; The method described in Article 27, including: Article 29 The third message includes: an instruction to initialize, modify or cancel the configuration for said lower layer signaling based cell change or addition; The identification information of the terminal device, or Identification information of a set of candidate cells of the second DU; The method according to claim 27, comprising at least one of the following: Article 30 The target cell is associated with a second DU, and the method includes: sending a fourth message to the second DU, indicating cancellation of the configuration for the lower layer signaling based cell change or addition; The method according to Article 14 or Article 20, further comprising: Article 31 receiving a second message from the first DU to request cancellation of the configuration for the lower layer signaling based cell change or addition; The method according to Article 14 or Article 20, further comprising: Article 32 The target cell is associated with a second DU, and the method includes: receiving a fifth message from the second DU to request cancellation of the configuration for the lower layer signaling based cell change or addition; The method according to Article 14 or Article 20, further comprising: Article 33 receiving, from the first DU, a first configuration for lower layer measurement and reporting for a set of candidate cells of the first DU; sending the first configuration to at least one candidate DU; The method according to Article 14 or Article 20, further comprising: Article 34 receiving, from the at least one candidate DU, a second configuration for lower layer measurement and reporting for a set of candidate cells of the at least one candidate DU; Sending the second configuration to the first DU; The method according to Article 14 or Article 20, further comprising: Article 35 Sending information of a set of candidate cells of at least one candidate DU to the first DU; receiving, from the first DU, a third configuration for lower layer measurement and reporting for the set of candidate cells of the at least one candidate DU; The method according to Article 14 or Article 20, further comprising: Article 36 The method comprises: Sending information of a set of candidate cells of the first DU to at least one candidate DU; receiving, from the at least one candidate DU, a fourth configuration for lower layer measurement and reporting for the set of candidate cells of the first DU; The method according to Article 14 or Article 20, further comprising: Article 37 1. A method of communication comprising: receiving, in a second distributed unit (DU), an indication from a central unit (CU) indicating that a lower layer signaling-based cell change or add is triggered for a target cell associated with the second DU; sending an acknowledgement to the CU regarding the trigger; The method includes: Article 38 The instructions include: the identity of the target cell; or Reference signal (RS) or transmission configuration indicator (TCI) information of the target cell; The method according to claim 37, comprising at least one of the following: Article 39 The acknowledgement response may include: a dedicated random access configuration for the cell change or addition; or setting a timing advance for the target cell; The method according to claim 37, comprising at least one of the following: Article 40 receiving a third message from the CU indicating an initialization or modification of a configuration for the lower layer signaling based cell change or addition; sending a positive response to the second message to the CU if the terminal device context is successfully established; sending a negative response to the second message to the CU if the context of the terminal device is not successfully established; The method according to clause 37, further comprising: Article 41 the third message indicating the initialization of the configuration, and sending the positive response transmitting, within the positive response, identities of a set of candidate cells of the second DU; The method according to Article 40, including: Article 42 The third message includes: an instruction to initialize, modify or cancel the configuration for said lower layer signaling based cell change or addition; Identification information of the terminal device, or Identification information of a set of candidate cells of the second DU; The method according to claim 40, comprising at least one of the following: Article 43 receiving a fourth message from the CU, the fourth message indicating cancellation of the configuration for the lower layer signaling based cell change or addition; The method according to clause 37, further comprising: Article 44 sending a fifth message to the CU to request cancellation of the configuration for the lower layer signaling based cell change or addition; The method according to clause 37, further comprising: Article 45 Sending to the CU a configuration for lower layer measurement and reporting for a set of candidate cells of the second DU; receiving from the CU a configuration for lower layer measurement and reporting for a set of candidate cells of a first DU; The method according to clause 37, further comprising: Article 46 receiving information of a set of candidate cells of a first DU from the CU; generating a fifth configuration for lower layer measurement and reporting for the set of candidate cells of the first DU; sending the fifth configuration to the CU; The method according to clause 37, further comprising: Article 47 A processor configured to cause a distributed unit (DU) to execute the method according to any one of Articles 1 to 19 or any one of Articles 37 to 46. D.U. Article 48 A processor configured to cause a central unit (CU) to execute the method according to any one of Articles 20 to 36. CU.

[0238] Overall, various embodiments of the present disclosure may be implemented in hardware or special purpose circuits, software, logic, or any combination thereof. Some aspects may be implemented in hardware, while other aspects may be implemented in firmware or software that may be executed by a controller, microprocessor, or other computing device. Although various aspects of the embodiments of the present disclosure have been illustrated and described using block diagrams, flow charts, or some other pictorial representations, it should be understood that the blocks, devices, systems, techniques, or methods described herein may be implemented, by way of non-limiting examples, in hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing device, or any combination thereof.

[0239] The present disclosure also provides at least one computer program product tangibly stored on a non-transitory computer-readable storage medium. The computer program product includes computer-executable instructions, such as instructions included in a program module, that execute in a device on a target real or virtual processor to perform the process or method described above with reference to Figures 2-9. Generally, program modules include routines, programs, libraries, objects, classes, components, data structures, etc. that perform particular tasks or implement particular abstract data types. In various embodiments, the functionality of the program modules may be combined or split between program modules as appropriate. The machine-executable instructions of the program modules may be executed in local or distributed devices. In a distributed device, the program modules may be located in both local and remote storage media.

[0240] The program codes for carrying out the methods of the present disclosure may be written in any combination of one or more programming languages. These program codes may be provided to a processor or controller of a general purpose computer, a special purpose computer, or other programmable data processing equipment, and when executed by the processor or controller, the program code causes the functions / operations specified in the flowcharts and / or block diagrams to be implemented. The program code may run entirely on the machine, partially on the machine, as a separate software package, partially on the machine and partially on a remote machine, or entirely on a remote machine or server.

[0241] The above program code may be embodied on a machine-readable medium, which may be any tangible medium that contains or stores a program for use by or in conjunction with an instruction execution system, apparatus, or device. The machine-readable medium may be a machine-readable signal medium or a machine-readable storage medium. The machine-readable medium may include, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples of machine-readable storage media include electrical connections, including one or more wires, a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable-programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

[0242] It should be understood that although operations have been described in a particular order, it is not required that such operations be performed in the particular order or sequence shown, or that all of the operations shown be performed, in order to achieve desired results. In some situations, multitasking and parallel processing may be advantageous. Similarly, although the above discussion includes details of some specific embodiments, these should not be construed as limitations on the scope of the disclosure, but rather as descriptions of features that may be specific to certain embodiments. Some features that are described in the context of individual embodiments may be implemented in combination in an embodiment. Conversely, various features that are described in the context of an embodiment may be implemented in multiple embodiments separately or in any suitable subcombination.

[0243] Although the present disclosure has been described in language specific to structural features and / or methodological acts, it is to be understood that the present disclosure, as defined by the appended claims, is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims.

Claims

1. 1. A method of communication comprising: sending, in a first distributed unit (DU), to a central unit (CU), first information about at least one candidate cell for lower layer signaling-based cell change or addition; receiving, from the CU, second information regarding a target cell for the lower layer signaling based cell change or addition; The method includes:

2. The first information is an identity of the at least one candidate cell; reference signal (RS) or transmission configuration indicator (TCI) information of the at least one candidate cell; or Measurement results of the at least one candidate cell; The method of claim 1 , comprising at least one of:

3. The second information is An identity of the target cell; Reference signal (RS) or transmission configuration indicator (TCI) information of the target cell; a dedicated random access configuration for the cell change or addition; or setting a timing advance for the target cell; The method of claim 1 , comprising at least one of:

4. receiving a first message from the CU indicating initialization, modification, or cancellation of a configuration for the lower layer signaling based cell change or addition; sending a positive response to the first message in response to a determination that a context of the terminal device has been successfully modified based on the first message; sending a negative response to the first message in response to a determination that the context of the terminal device was not successfully modified based on the first message; and The method of claim 1 further comprising:

5. The first message comprises: an instruction to initialize, modify or cancel the configuration for said lower layer signaling based cell change or addition; Identities of a set of candidate cells for the first DU for the lower layer signaling based cell change or addition; or Identities of a set of candidate cells to be cancelled for the lower layer signalling based cell change or addition; The method of claim 4 , comprising at least one of:

6. The first message indicates the initialization of the configuration, and sending the positive response includes: determining a set of candidate cells for the first DU for the lower layer signaling based cell change or addition; transmitting, in the positive response, identities of the set of candidate cells for the first DU to the CU; 5. The method of claim 4, comprising:

7. sending a second message to the CU to request cancellation of the configuration for the lower layer signaling based cell change or addition; The method of claim 1 further comprising:

8. sending a first configuration for lower layer measurement and reporting for a set of candidate cells of the first DU to the CU; receiving from the CU a second configuration for lower layer measurement and reporting for a set of candidate cells of at least one candidate DU; The method of claim 1 further comprising:

9. receiving information of a set of candidate cells of at least one candidate DU from the CU; generating a third configuration for lower layer measurement and reporting for the set of candidate cells of the at least one candidate DU; sending the third configuration to the CU; The method of claim 1 further comprising:

10. 1. A method of communication comprising: receiving, at a central unit (CU), from a first distributed unit (DU), first information regarding at least one candidate cell for a lower layer signaling-based cell change or addition; determining a target cell for the lower layer signaling based cell change or addition based on the first information; transmitting second information regarding a target cell for the lower layer signaling based cell change or addition to the first DU; The method includes:

11. The first information is an identity of the at least one candidate cell; reference signal (RS) or transmission configuration indicator (TCI) information of the at least one candidate cell; or Measurement results of the at least one candidate cell; The method of claim 10, comprising at least one of:

12. The second information is An identity of the target cell; Reference signal (RS) or transmission configuration indicator (TCI) information of the target cell; a dedicated random access configuration for the cell change or addition; or setting a timing advance for the target cell; The method of claim 10, comprising at least one of:

13. The target cell is associated with a second DU, and the method further comprises: sending an indication to the second DU indicating that the cell change or addition is triggered for the target cell; receiving an acknowledgment for the trigger from the second DU; The method of claim 10 further comprising:

14. The instructions include: the identity of the target cell; or Reference signal (RS) or transmission configuration indicator (TCI) information of the target cell; The method of claim 13 , comprising at least one of:

15. The acknowledgement response may include: a dedicated random access configuration for the cell change or addition; or setting a timing advance for the target cell; The method of claim 13 , comprising at least one of:

16. sending a first message to the first DU indicating initialization, modification or cancellation of a configuration for the lower layer signaling based cell change or addition; receiving a positive response to the first message from the first DU if a context of a terminal device is successfully modified based on the first message; receiving a negative response to the first message from the first DU if the context of the terminal device is not successfully modified based on the first message; The method of claim 10 further comprising:

17. The first message indicates the initialization of the configuration, and receiving the positive response indicates receiving, in the positive response, identities of a set of candidate cells for the first DU; 17. The method of claim 16, comprising:

18. The target cell is associated with a second DU, and the method further comprises: sending a third message to the second DU indicating an initialization or modification of a configuration for the lower layer signaling based cell change or addition; receiving a positive response to the second message from the second DU if a terminal device context is successfully established; receiving a negative response to the second message from the second DU if the context of the terminal device is not successfully established; The method of claim 10 further comprising:

19. The target cell is associated with a second DU, and the method further comprises: sending a fourth message to the second DU indicating cancellation of the configuration for the lower layer signaling based cell change or addition; The method of claim 10 further comprising:

20. A distributed unit (DU), A processor configured to cause the DU to perform the method of any one of claims 1 to 9. D.U.

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