Communication method and device, and computer storage medium

Abstract

The embodiment of the invention relates to a communication method and device and a computer readable medium. The terminal device receives information associated with a low-layer signaling-based cell handover, and determines whether to perform a procedure set during the low-layer signaling-based cell handover based on the information. The process set comprises at least one of the following: PDCP recovery for a DRB set; the PDCP SDU for the SRB set is discarded; performing RRC reconstruction on the DRB set and the SRB set; or the MAC is reset. In this way, the terminal device may determine whether to perform or skip some L2 processes for a subsequent low-layer-based movement process.

Description

Technical Field

[0001] Embodiments of the present disclosure generally relate to the field of telecommunications, and more particularly, to communication methods, devices, and computer storage media based on low-layer signaling. Background Art

[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 change or addition or release of the serving cell. Currently, it has been proposed to trigger a change or addition or release of the serving cell through low-layer signaling such as layer 1 (L1) or layer 2 (L2) signaling. In one scheme, data transmission is performed using a change of the serving cell upon receiving the low-layer signaling, which is also referred to as a low-layer based mobility procedure. In this way, latency, overhead, and interruption time can be reduced. However, the scheme for the low-layer based mobility procedure is still not perfect and needs further development. Summary of the Invention

[0003] Generally speaking, embodiments of the present disclosure provide methods, devices, and computer storage media for communication based on low-layer signaling.

[0004] In a first aspect, a communication method is provided. The method includes: at a terminal device, receiving information associated with a cell handover based on low-layer signaling from a network device; and determining, based on the information, whether to perform a set of procedures during the cell handover based on low-layer signaling, the set of procedures including at least one of the following: packet data convergence protocol recovery for a set of data radio bearers; packet data convergence protocol service data unit discard for a set of signaling radio bearers; radio link control reconstruction for a set of data radio bearers and a set of signaling radio bearers; or media access control reset.

[0005] In a second aspect, a communication method is provided. The method includes: at a terminal device, receiving low-layer signaling indicating a cell handover to a target cell from a network device; and sending an indication to the network device indicating completion of the cell handover, the indication including information about the target cell.

[0006] In a third aspect, a communication method is provided. The method includes: at a network device, sending information associated with a cell handover based on low-layer signaling to a terminal device for determining whether to perform a set of procedures during the cell handover based on low-layer signaling, the set of procedures including at least one of the following: packet data convergence protocol recovery for a set of data radio bearers; packet data convergence protocol service data unit discard for a set of signaling radio bearers; radio link control reconstruction for a set of data radio bearers and a set of signaling radio bearers; or media access control reset.

[0007] In a fourth aspect, a communication method is provided. The method includes: at a network device, sending lower layer signaling indicating a cell handover to a target cell to a terminal device; and receiving, from the terminal device, an indication indicating completion of the cell handover, the indication including information of the target cell.

[0008] In a fifth aspect, a communication device is provided. The device includes a processor configured to cause the device to execute the method according to any one of the first to fourth aspects of the present disclosure.

[0009] In a sixth aspect, a computer-readable medium storing instructions is provided. When the instructions are run on at least one processor, the at least one processor is caused to execute the method according to any one of the first to fourth aspects of the present disclosure.

[0010] Other features of the present disclosure will become readily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Through a more detailed description of some embodiments of the present disclosure in the drawings, the above and other objects, features, and beneficial effects of the present disclosure will become more obvious, where:

[0012] Figure 1A An example communication network in which some embodiments of the present disclosure can be implemented is shown;

[0013] Figure 1B A schematic diagram showing network protocol layer entities that can be established at a device for a user plane (UP) protocol stack according to some embodiments of the present disclosure is shown;

[0014] Figure 1C A schematic diagram showing network protocol layer entities that can be established at a device for a control plane (CP) protocol stack according to some embodiments of the present disclosure is shown;

[0015] Figure 1D A schematic diagram of a central unit (CU) / distributed unit (DU) architecture in which some embodiments of the present disclosure can be implemented is shown;

[0016] Figure 1E A schematic diagram showing a process of low-layer-based mobility in which some embodiments of the present disclosure can be implemented is shown;

[0017] Figure 2 A schematic diagram showing a communication process according to an embodiment of the present disclosure is shown;

[0018] Figure 3A A schematic diagram showing an example communication process based on lower layer signaling indicating a cell handover according to an embodiment of the present disclosure is shown;

[0019] Figure 3B Shows a schematic diagram illustrating an example communication process based on a configuration for cell handover based on lower layer signaling according to an embodiment of the present disclosure;

[0020] Figure 4 Shows a schematic diagram illustrating another communication process according to an embodiment of the present disclosure;

[0021] Figure 5A Shows a schematic diagram illustrating an example communication process based on lower layer signaling according to an embodiment of the present disclosure;

[0022] Figure 5B Shows a schematic diagram illustrating an example communication process based on radio resource control (RRC) signaling according to an embodiment of the present disclosure;

[0023] Figure 6 Shows an example communication method implemented at a terminal device according to some embodiments of the present disclosure;

[0024] Figure 7 Shows another example communication method implemented at a terminal device according to some embodiments of the present disclosure;

[0025] Figure 8 Shows an example communication method implemented at a network device according to some embodiments of the present disclosure;

[0026] Figure 9 Shows another example communication method implemented at a network device according to some embodiments of the present disclosure; and

[0027] Figure 10 Is a simplified block diagram of a device suitable for implementing embodiments of the present disclosure.

[0028] In all the figures, the same or similar reference numerals denote the same or similar elements. Detailed Description of the Invention

[0029] The principles of the present disclosure will now be described with reference to some embodiments. It should be understood that the description of these embodiments is for illustrative purposes only and helps those skilled in the art to understand and implement the present disclosure, without implying any limitation to the scope of the disclosure. The disclosure described herein can be implemented in various ways different from those described below.

[0030] 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 the present disclosure pertains.

[0031] As used herein, the term "terminal device" refers to any device with wireless or wired communication capabilities. Examples of terminal devices include, but are not limited to, user equipment (UE), personal computers, desktop computers, mobile phones, cellular phones, smartphones, personal digital assistants (PDA), portable computers, tablets, wearable devices, Internet of Things (IoT) devices, ultra-reliable and low-latency communication (URLLC) devices, Internet of Everything (IoE) devices, machine type communication (MTC) devices, in-vehicle devices for V2X communication (where X represents pedestrians, vehicles, or infrastructure / networks), devices for integrated access and backhaul (IAB), space vehicles or aerial vehicles in non-terrestrial networks (NTN) including satellites and high-altitude platforms (HAP) containing unmanned aerial vehicle systems (UAS), extended reality (XR) devices including different types of reality such as augmented reality (AR), mixed reality (MR), and virtual reality (VR), unmanned aerial vehicles (UAV), commonly referred to as drones (which are aircraft without any human pilots), devices on high-speed trains (HST), or image capture devices such as digital cameras, sensors, gaming devices, music storage and playback devices, or Internet devices capable of wireless or wired Internet access and browsing, etc. The "terminal device" may also have "multicast / broadcast" features to support public safety and mission-critical, V2X applications, transparent IPv4 / IPv6 multicast delivery, IPTV, smart TV, radio services, software delivery over the air, group communication, and IoI applications. It may also incorporate one or more user identity modules (SIM), known as multi-SIM. The term "terminal device" may be used interchangeably with UE, mobile station, subscriber station, mobile terminal, user terminal, or wireless device.

[0032] The term "network device" refers to a device capable of providing or controlling a cell or coverage with which a terminal device can communicate. Examples of network devices include, but are not limited to: Node B (NodeB or NB), evolved Node B (eNodeB or eNB), next-generation Node B (gNB), transmit receive point (TRP), remote radio unit (RRU), radio head (RH), remote radio head (RRH), IAB node, low-power nodes such as femto nodes, pico nodes, reconfigurable intelligent surface (RIS), etc.

[0033] The terminal device or network device may have artificial intelligence (AI) or machine learning capabilities. It generally includes a model that has been trained based on a large amount of collected data for a specific function and can be used to predict some information.

[0034] A terminal or network device can operate on several frequency ranges, such as FR1 (410 MHz to 7125 MHz), FR2 (24.25 GHz to 71 GHz), frequency bands greater than 100 GHz, and the terahertz (THz) frequency band. It can also operate on licensed / unlicensed / shared spectrum. In a multi-radio dual-connection (MR-DC) application scenario, a terminal device can have more than one connection with a network device. The terminal device or network device can operate in full-duplex, flexible-duplex, and cross-split duplex modes.

[0035] Embodiments of the present disclosure can be implemented in test equipment, such as a signal generator, a signal analyzer, a spectrum analyzer, a network analyzer, a test terminal device, a test network device, and a channel emulator.

[0036] In one embodiment, a terminal device can be connected to a first network device and a second network device. One of the first network device and the second network device can be a master node, and the other can be a secondary node. The first network device and the second network device can use different radio access technologies (RATs). In one embodiment, the first network device can be a first RAT device, and the second network device can be a second RAT device. In one embodiment, the first RAT device is an eNB and the second RAT device is a gNB. Information related to different RATs can be sent from at least one of the first network device or the second network device to the terminal device. In one embodiment, the first information can be sent from the first network device to the terminal device, and the second information can be sent from the second network device to the terminal device directly or via the first network device. In one embodiment, information related to the configuration of the terminal device configured by the second network device can be sent from the second network device via the first network device. Information related to the reconfiguration of the terminal device configured by the second network device can be sent from the second network device to the terminal device directly or via the first network device.

[0037] As used herein, the singular forms "a", "an", and "the" are also intended to include the plural forms unless the context clearly indicates otherwise. The term "comprising" and its variants will be construed as open-ended terms, meaning "including but not limited to". The term "based on" will be construed as "at least partially based on". The terms "one embodiment" and "embodiment" will be construed as "at least one embodiment". The term "another embodiment" will be construed as "at least one other embodiment". The terms "first", "second", etc. can refer to different or the same objects. Other explicit and implicit definitions may be included below.

[0038] In some examples, values, processes, or devices are referred to as "optimal", "lowest", "highest", "minimum", "maximum", etc. It should be understood that such descriptions are intended to indicate that a selection can be made among many alternative functions used, and such a selection does not necessarily need to be better, smaller, higher, or more preferred than other selections.

[0039] In the context of the present disclosure, the term "cell handover" may be used interchangeably with "synchronous reconfiguration for a secondary cell group (SCG) or a primary cell group (MCG)" or "cell change". The term "PSCell" refers to the SpCell of the SCG, the term "PCell" refers to the SpCell of the MCG, and the term "SpCell" refers to the primary cell of the SCG or MCG. The term "SCell" refers to a secondary cell. The term "L1 / L2-based mobility" may be used interchangeably with "L1 / L2-triggered mobility" or "L1-triggered mobility" or "L2-triggered mobility" (abbreviated as LTM). 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 sending and receiving of data.

[0040] As described above, when the UE moves from the coverage area of one cell to the coverage area of another cell, a change or addition or release of the serving cell may be required. Traditionally, a change or addition or release of the serving cell is triggered by layer 3 (L3) measurements and is completed by a synchronous reconfiguration for a primary cell (PCell) and a primary and secondary cell (PSCell) change triggered by RRC signaling. All cases involve a complete L2 and L1 reset, resulting in a longer latency, a greater overhead, and a longer interruption time than beam switching mobility.

[0041] It has been proposed to trigger cell handover based on lower layer signaling such as L1 or L2 signaling. In this way, the latency, overhead, and interruption time can be reduced. However, there are still some problems during cell handover based on lower layer signaling.

[0042] In traditional handover or PSCell change, whether to perform L2 processes (such as packet data convergence protocol (PDCP) recovery, PDCP service data unit (SDU) discard, and radio link control (RLC) reconstruction) is based on the received RRC reconfiguration (RRCReconfiguration), and a medium access control (MAC) reset is always performed. For lower layer-based mobility processes, some processes in the L2 process can be omitted for a distributed unit-internal (DU-internal) mobility scenario. However, the trajectory of the UE is unpredictable, so it is impossible to configure whether to perform some processes in the L2 process. In addition, it is not clear which one or which ones of the L2 processes can be omitted.

[0043] In view of this, embodiments of the present disclosure provide a communication solution to overcome the above problems and other potential problems. In this solution, the network device sends information associated with cell handover based on low-layer signaling, and based on this information, the terminal device determines whether to execute a set of procedures. The set of procedures includes at least one of the following: PDCP recovery for a data radio bearer set (DRB); PDCP SDU discard for a signaling radio bearer (SRB) set; RLC re-establishment for a DRB set and an SRB set; or MAC reset.

[0044] In this way, the terminal device can determine whether to execute or skip some L2 procedures for subsequent low-layer based mobility procedures (i.e., subsequent LTM).

[0045] In addition, for traditional mobility procedures, when performing a handover or PSCell change, the UE generates an RRC reconfiguration complete (RRCReconfigurationComplete) message as a completion indication to the network. However, it is still unclear whether the configuration for each candidate cell includes an RRC reconfiguration message. If there is no RRC reconfiguration message for each candidate cell, the question is what is used as a response to the network as a completion indication.

[0046] In view of this, embodiments of the present disclosure provide another communication solution to overcome this problem and other potential problems. In this solution, the terminal device receives low-layer signaling indicating a cell handover to a target cell from the network device, and sends an indication indicating the completion of the cell handover to the network device. The indication includes information about the target cell. In this way, the network can be aware of the completion or confirmation of low-layer based mobility.

[0047] The principles and implementations of the present disclosure will be described in detail below with reference to the accompanying drawings.

[0048] Example of a communication network

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

[0050] It should be understood that Figure 1AThe number of devices in [description] is provided for illustrative purposes and does not imply any limitation to the present disclosure. The communication network 100A may include any suitable number of network devices and / or terminal devices suitable for implementing embodiments of the present disclosure. In addition, each of the network devices 120 and 130 may provide more cells for the terminal device 110.

[0051] As Figure 1A shown, the terminal device 110 may communicate with the network device 120 or 130 via a channel such as a wireless communication channel. The communication in the 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, Advanced LTE (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), etc. Embodiments of the present disclosure may be implemented according to any generation of communication protocols known currently or developed in the future. Examples of communication protocols include but are not limited to the first generation (1G), second generation (2G), 2.5G, 2.75G, third generation (3G), fourth generation (4G), 4.5G, fifth generation (5G) communication protocol, 5.5G, 5G Advanced Network or sixth generation (6G) network.

[0052] The communication in the direction from the terminal device 110 to the network device 120 or 130 is referred to as uplink (UL) communication, while the communication in the opposite direction from the network device 120 or 130 to the terminal device 110 is referred to as downlink (DL) communication. The terminal device 110 may move between the cells of the network devices 120, 130 and possibly other network devices. In UL communication, the terminal device 110 may send UL data and control information to the network device 120 or 130 via the UL channel. In DL communication, the network device 120 or 130 may send DL data and control information to the terminal device 110 via the DL channel.

[0053] The communication in the communication network 100A may be implemented according to the UP protocol stack and the CP protocol stack. Generally, for a communication device (such as a terminal device or a network device), there are multiple entities for multiple network protocol layers in the protocol stack, and these entities may be configured to perform corresponding processing on the data or signaling sent from and received by the communication device. Figure 1B FIG. 100B shows a schematic diagram illustrating network protocol layer entities that may be established for the UP protocol stack at a device according to some embodiments of the present disclosure. For convenience, the following description is given by taking the communication between the terminal device 110 and the network device 120 as an example. It should be understood that the following description also applies to 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 Figure 1B shown, in UP, each of the terminal device 110 and the network device 120 may include: an entity for the L1 layer, i.e., an entity for the physical (PHY) layer (also referred to as a PHY entity), and one or more entities for higher layers (L2 and layer 3 (L3) layers, or higher layers), including an entity for the MAC layer (also referred to as a MAC entity), an entity for the RLC layer (also referred to as an RLC entity), an entity for the PDCP layer (also referred to as a PDCP entity), and an entity for the service data application protocol (SDAP) layer (also referred to as an SDAP entity, which is established in 5G and higher-generation networks). In some cases, the PHY, MAC, RLC, PDCP, and SDAP entities are in a stacked structure.

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

[0057] In the context of the present 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 the present invention, L1 or L2 may also be collectively referred to as the lower layer, and L3 may also be referred to as the higher layer. Thus, L1 or L2 signaling may also be referred to as lower-layer signaling, and L3 signaling may also be referred to as higher-layer signaling.

[0058] Generally, communication channels are classified into logical channels, transport channels, and physical channels. A physical channel is the channel through which the PHY layer actually transmits information. For example, physical channels may include Physical Uplink Control Channel (PUCCH), Physical Uplink Shared Channel (PUSCH), Physical Random Access Channel (PRACH), PDCCH, Physical Downlink Shared Channel (PDSCH), and Physical Broadcast Channel (PBCH).

[0059] A transport channel is a channel between the PHY layer and the MAC layer. For example, transport channels may include Broadcast Channel (BCH), Downlink Shared Channel (DL-SCH), Paging Channel (PCH), Uplink Shared Channel (UL-SCH), and Random Access Channel (RACH).

[0060] A logical channel is a channel between the MAC layer and the RLC layer. For example, logical channels may include Dedicated Control Channel (DCCH), Common Control Channel (CCCH), Paging Control Channel (PCCH), Broadcast Control Channel (BCCH), and Dedicated Traffic Channel (DTCH).

[0061] Generally, the 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. Four types of SRBs can be defined in the RRC layer, namely SRB0, SRB1, SRB2, and SRB3. SRB0 uses CCCH for RRC connection establishment or re-establishment. SRB1 uses DCCH and is established when the RRC connection is established. SRB2 uses DCCH and is established during RRC reconfiguration and after initial security activation. SRB3 uses DCCH and is established between the terminal device 110 and the SN when dual connectivity is established.

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

[0063] In the context of the present disclosure, a CU (also referred to herein as gNB-CU) is a logical node that masters the RRC, SDAP, and PDCP protocols of a gNB or the RRC and PDCP protocols of an en-gNB, and this logical node controls the operations 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 of the RLC, MAC, and PHY layers of a master gNB or en-gNB, and its operations are 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 Figure 1D shown, a CU 141 is shown. It should be understood that more CUs may be included. The CU 141 may communicate with multiple DUs. Here, for illustration purposes, two DUs 151 and 152 are shown. It should be understood that more DUs may also be provided for the implementation of the embodiments of the present disclosure. Although not shown, the CU 141 may be responsible for completing the functions of the SDAP entity and the PDCP entity, and the DU 151 or 152 may be responsible for completing the functions of the RLC entity, the MAC entity, and the PHY entity.

[0065] The DU 151 may provide cells 161, 162, and 163. The DU 152 may provide cells 164, 165, and 166. It should be understood that this is only an example, and more or fewer cells are also feasible. The terminal device 110 may communicate with any one of these cells.

[0066] In some embodiments, the terminal device 110 may switch from one cell to another under the control of the same CU and the same DU. For example, the terminal device 110 may switch from one cell 161 to another cell 162. This is referred to as an in-CU in-DU serving cell handover. In some embodiments, the terminal device 110 may switch from one cell to another under the control of the same CU and different DUs. For example, the terminal device 110 may switch from one cell 161 to another cell 164. In this case, a cell handover from one cell of the DU151 to another cell of the DU 152 will occur. This is referred to as an in-CU inter-DU serving cell handover. In another example, the terminal device 110 may switch from a cell of one DU to a cell of another DU under the control of different CUs. In this case, a handover from one CU to another CU will occur. This is referred to as an inter-CU handover.

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

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

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

[0070] In some cases, the terminal device 110 may receive L1 or L2 signaling from the network device 120 indicating the addition or change or release of a serving cell. When a serving cell is added or changed or released, the terminal device 110 may perform data transmission using the addition, modification, or change of the serving cell. This process is referred to as low-layer-based mobility.

[0071] Figure 1E A schematic diagram illustrating a process 100E of low-layer-based mobility in which some embodiments of the present disclosure may be implemented is shown. For the purpose of discussion, reference will be made to Figure 1A Describe process 100E. Process 100E may involve the terminal device 110 and the network device 120 as shown in Figure 1A . The network device 120 may be an MN or an 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] As shown in Figure 1EAs shown, the network device 120 may send 170 RRC reconfiguration to the terminal device 110, and the RRC reconfiguration includes an RRC configuration set corresponding to a set of candidate cells that allow L1 / L2-based mobility. The network device 120 may also send 171 the configuration of the beams of the candidate cells (e.g., synchronization signal and physical broadcast channel block (SSB) or channel state information reference signal (CSI-RS)) to the terminal device 110 for L1 measurement.

[0073] The terminal device 110 may perform 172 L1 measurement based on this configuration. If the beam meets a certain condition, e.g., the quality of the beam is higher than a threshold quality, the terminal device 110 may report 173 an indication of the beam (e.g., an identifier (ID) associated with the beam) to the network device 120.

[0074] The network device 120 may send 174 L1 / L2 signaling (e.g., downlink control information (DCI) or medium access control (MAC) control element (CE)) to the terminal device 110. The L1 / L2 signaling indicates that the transmission configuration indicator (TCI) state for the cell in the candidate cells is activated together with cell handover.

[0075] Upon receiving the L1 / L2 signaling, the terminal device 110 may perform cell handover 175. For example, the lower layer (e.g., PHY layer or MAC layer) of the terminal device 110 indicates information about cell handover to the RRC layer of the terminal device 110, such as the ID associated with the target cell. The L1 / L2 signaling may also indicate that the TCI state for cells with different physical cell identifiers (PCI) is activated together with cell handover. Upon receiving this indication, the RRC layer performs cell handover by applying the configuration corresponding to the target cell. The target cell may be the PCell, PSCell, or SCell of the terminal device 110. And, the terminal device 110 may start data transmission with the target cell using the pre-configured UE-specific channel and the activated TCI state.

[0076] For low-layer-based mobility, some procedures in the L2 process may be omitted for the in-DU mobility scenario to save mobility latency. However, the trajectory of the UE is unpredictable, so it is impossible to configure whether to perform some procedures in the L2 process. In addition, it is also unclear which one or which procedures in the L2 process can be omitted.

[0077] Embodiments of the present disclosure provide a solution for indicating whether to perform some procedures in the L2 process. Details thereof will be described with reference to Figures 2 to 3B description.

[0078] Example implementation of the decision on whether to execute the L2 process

[0079] Figure 2A schematic diagram illustrating a communication process 200 according to an embodiment of the present disclosure is shown. For the purpose of discussion, reference will be made to Figure 1A to describe process 200. Process 200 may involve a terminal device 110 and a network device 120 as shown in Figure 1A . In this example, network device 120 serves terminal device 110.

[0080] As shown in Figure 2 , network device 120 may send 210 to terminal device 110 information associated with cell handover based on lower layer signaling (i.e., lower layer-based mobility). In some embodiments, the information may include information on whether to execute a set of processes for cell handover based on lower layer signaling (also referred to herein as first information for convenience). In some embodiments, the information may include information to help terminal device 110 decide whether to execute a set of processes for cell handover based on lower layer signaling (also referred to herein as second information for convenience).

[0081] Continuing to refer to Figure 2 , based on the first information or the second information, terminal device 110 determines 220 whether to execute the set of processes for cell handover based on lower layer signaling. In some embodiments, the set of processes may include PDCP SDU discard for a set of SRBs. For example, for a set of SRBs, the PDCP entity of terminal device 110 may discard all stored PDCP SDUs and PDCP protocol data units (PDUs).

[0082] In some alternative or additional embodiments, the set of processes may include PDCP recovery for a set of DRBs. In some alternative or additional embodiments, the set of processes may include RLC reconstruction for a set of DRBs and a set of SRBs. In some alternative or additional embodiments, the set of processes may include MAC reset. It should be understood that the set of processes may include any combination of the above processes and any other suitable processes. In some embodiments, the set of processes may also be referred to as an L2 reset process.

[0083] In some embodiments where the set of processes is not executed, terminal device 110 may perform an LTM-specific MAC reset (also referred to herein as a partial MAC reset). In some embodiments for the LTM-specific MAC reset, terminal device 110 may continue processes related to data transmission / reception processing in the MAC layer and may perform at least one of the following operations:

[0084] · Do not reset Bj of each logical channel to zero / maintain Bj of each logical channel;

[0085] · Do not cancel / maintain the triggered scheduling request process;

[0086] · Do not cancel / maintain the triggered buffer status report procedure;

[0087] · Do not clear / maintain the buffer for all Hybrid Automatic Repeat reQuest (HARQ) processes;

[0088] · Do not set the New Data Indicator (NDI) for all uplink HARQ processes to 0 / maintain the NDI for all HARQ processes; or

[0089] · Do not consider the time alignment timer of all Timing Advance Groups (TAGs) to have expired / maintain the time alignment timer of all TAGs.

[0090] In some alternative embodiments for LTM-specific MAC reset, the terminal device 110 may perform at least one of the following operations:

[0091] · Stop all timers (if running);

[0092] · Stop the ongoing Random Access (RA) procedure, if any;

[0093] · Discard the contention-free RA resources for explicit signaling notification for both 4-step RA type and 2-step RA type, if any;

[0094] · Empty the Msg3 buffer;

[0095] · Empty the MSGA buffer;

[0096] · Cancel the triggered power headroom report procedure, if any;

[0097] · Cancel the triggered Listen Before Talk (LBT) failure for consistency, if any;

[0098] · Cancel the triggered Beam Failure Report (BFR), if any;

[0099] · Cancel the triggered recommended bitrate query procedure, if any;

[0100] · Cancel the triggered configuration uplink grant confirmation, if any;

[0101] · Cancel the triggered desired guard symbol query, if any;

[0102] · Release the temporary Cell Radio Network Temporary Identifier (C-RNTI), if any;

[0103] · Reset all Beam Failure Instance (BFI) counters (BFI_COUNTER); or

[0104] · Reset all LBT counters (LBT_COUNTER).

[0105] For illustration, some example embodiments will be described in conjunction with Embodiment 1 and Embodiment 2.

[0106] Embodiment 1

[0107] In this embodiment, the network device 120 may send first information in the low-layer signaling indicating a cell handover. In some embodiments, the low-layer signaling may be a MAC CE. In some embodiments, the low-layer signaling may be a DCI. For illustration, it will be described in detail in conjunction with Figure 3A Given a detailed description.

[0108] Figure 3A FIG. shows a schematic diagram illustrating an example communication process 300 based on low-layer signaling indicating a cell handover according to an embodiment of the present disclosure. For the purpose of discussion, process 300A will be described with reference to Figure 1A Describe process 300A. Process 300A may involve, for example, Figure 1A As shown, the terminal device 110 and the network device 120. In this example, the network device 120 serves the terminal device 110.

[0109] As Figure 3A shown, the network device 120 may send 310 low-layer signaling indicating a cell handover to the terminal device 110. In some embodiments, the CU (e.g., CU 141) of the network device 120 may send an indication to the source DU (e.g., DU151) of the network device 120 indicating whether to perform the set of processes. Based on this indication, the source DU may generate low-layer signaling indicating a cell handover. The source DU may send the generated low-layer signaling to the terminal device 110.

[0110] The low-layer signaling includes first information regarding whether to perform a set of processes for a cell handover based on the low-layer signaling. In some embodiments, the low-layer signaling may be a MAC CE. In some embodiments, the low-layer signaling may be a DCI.

[0111] In some embodiments, the first information may include an indication indicating whether to perform the set of processes. In some embodiments, the indication may include a single indication regarding whether to perform all processes in the set of processes. In some embodiments, the indication may include a set of indications. The indications in the set of indications indicate whether the processes in the set of processes are performed.

[0112] In some alternative or additional embodiments, the first information may include an indication indicating the mobile scenario of the cell handover.

[0113] Refer to Figure 3A, the terminal device 110 may determine based on the first information whether 320 is for a set of procedures for the cell handover execution process.

[0114] In some embodiments where the first information includes an indication indicating whether to execute the set of procedures, if the indication indicates that the set of procedures will not be executed, the terminal device 110 may determine not to execute the set of procedures. If the indication indicates to execute the set of procedures, the terminal device 110 may determine to execute the set of procedures.

[0115] In some embodiments where the first information includes an indication indicating the mobility scenario of the cell handover, if the mobility scenario of the cell handover is the CU-in DU-in scenario, the terminal device 110 may determine not to execute the set of procedures. If the mobility scenario of the cell handover is the CU-in DU-inter scenario, the terminal device 110 may determine to execute the set of procedures.

[0116] In some embodiments, upon receiving the first information, the lower layer (e.g., MAC layer) of the terminal device 110 may send an indication indicating the execution of the set of procedures to the upper layer (e.g., RRC, PDCP, and RLC layers) of the terminal device 110. The upper layer may execute the set of procedures. In some embodiments, upon receiving the first information, the lower layer may send an indication indicating whether to execute the set of procedures to the upper layer. The upper layer may execute or skip the set of procedures based on the indication from the lower layer.

[0117] In some embodiments, upon receiving the first information, the lower layer of the terminal device 110 may send an indication to the RRC layer, and the RRC layer may instruct the lower layer (PDCP, RLC, and MAC layers) to execute or skip the set of procedures. In some embodiments, the lower layer of the terminal device 110 may directly send the indication to the PDCP and RLC layers, and the PDCP and RLC layers execute or skip the set of procedures accordingly based on the indication from the lower layer (e.g., MAC layer).

[0118] In this way, the terminal device may decide whether to execute or skip some L2 procedures for subsequent lower-layer-based mobility.

[0119] Embodiment 2

[0120] In this embodiment, the network device 120 may send second information in the configuration for cell handover based on lower-layer signaling. In some embodiments, the network device 120 may send the configuration for cell handover based on lower-layer signaling in an RRC message, and the configuration includes auxiliary information (i.e., the second information) for the terminal device 110 to decide whether to execute the set of procedures. For illustration, it will be described in detail in conjunction with Figure 3B be given a detailed description.

[0121] Figure 3B FIG. shows a schematic diagram illustrating an example communication process 300B based on a configuration for cell handover based on low-layer signaling according to an embodiment of the present disclosure. For the purpose of discussion, reference will be made to Figure 1A describe process 300B. Process 300B may include as Figure 1A shown, a terminal device 110 and a network device 120. In this example, the network device 120 serves the terminal device 110.

[0122] As Figure 3B shown, the network device 120 may send 330 a configuration for cell handover based on low-layer signaling to the terminal device 110. The configuration includes second information.

[0123] In some embodiments, the second information may include information (e.g., identification) of a DU or cell group associated with a candidate cell in a candidate cell set.

[0124] In some embodiments, the second information may include an indication of whether to execute the process set during a cell handover from one candidate cell in the candidate cell set to another second candidate cell. For example, the second information may include multiple lists, and each list in the multiple lists indicates whether to execute the process set during a handover from the candidate cell to each other candidate cell for the candidate cell.

[0125] In some embodiments, the second information may include an indication of a cell handover from one candidate cell in the candidate cell set to another candidate cell that does not require execution of the process set. For example, the second information may include multiple lists, and each list in the multiple lists indicates one or more cell handovers from the candidate cell to other candidate cells that do not require execution of the process set for the candidate cell.

[0126] In some embodiments, the second information may include an indication of a cell handover from one candidate cell in the candidate cell set to another candidate cell that requires execution of the process set. For example, the second information may include multiple lists, and each list in the multiple lists indicates one or more cell handovers from the candidate cell to other candidate cells that require execution of the process set for the candidate cell.

[0127] Continuing to refer to Figure 3B , the network device 120 may also send 340 low-layer signaling indicating a cell handover to the terminal device 110. In this case, the terminal device 110 may determine 350 whether to execute the process set for the cell handover based on the second information.

[0128] In some embodiments where the second information includes information of a DU or a cell group associated with a candidate cell in a candidate cell set, if the target cell and the source cell associated with the cell handover are associated with different DUs or cell groups, the terminal device 110 may determine to execute the set of procedures. If the target cell and the source cell are associated with the same DU or cell group, the terminal device 110 may determine not to execute the set of procedures.

[0129] In some embodiments where the second information includes an indication of whether to execute the set of procedures during a cell handover from one candidate cell in the candidate cell set to another second candidate cell, the terminal device 110 may determine whether to execute the set of procedures during a cell handover from the source cell to the target cell based on this indication. If it is indicated to execute the set of procedures during the cell handover, the terminal device 110 may determine to execute the set of procedures. If it is not indicated to execute the set of procedures during the cell handover, the terminal device 110 may determine not to execute the set of procedures.

[0130] In some embodiments where the second information includes an indication of a cell handover from one candidate cell in the candidate cell set to another candidate cell that does not require the execution of the set of procedures, if the second information includes an indication of a cell handover from the source cell to the target cell, the terminal device 110 may determine not to execute the set of procedures. If the second information does not include an indication of a cell handover from the source cell to the target cell, the terminal device 110 may determine to execute the set of procedures.

[0131] In some embodiments where the second information includes an indication of a cell handover from one candidate cell in the candidate cell set to another candidate cell that requires the execution of the set of procedures, if the second information includes an indication of a cell handover from the source cell to the target cell, the terminal device 110 may determine to execute the set of procedures. If the second information does not include an indication of a cell handover from the source cell to the target cell, the terminal device 110 may determine not to execute the set of procedures.

[0132] In some embodiments, if the configuration does not include the second information, the terminal device 110 may determine to execute the set of procedures.

[0133] In some embodiments, the terminal device 110 may determine whether to execute the set of procedures for a subsequent cell handover based on the second information. In some embodiments, the terminal device 110 may determine whether to execute the set of procedures for a first cell handover after receiving an RRC reconfiguration for LTM based on the second information. In some embodiments, the terminal device 110 may determine to execute the set of procedures for a first cell handover after receiving an RRC reconfiguration for LTM based on the recoverPDCP information element (IE), discardOnPDCP IE, and reestablishRLC IE included in the configuration associated with the target candidate cell.

[0134] In this way, the terminal device may also decide whether to execute or skip some L2 procedures for subsequent lower-layer-based mobility.

[0135] Example implementation of the completion indication based on low - layer mobility

[0136] As described above, it is still unclear whether the configuration for each candidate cell includes an RRC reconfiguration message. If there is no RRC reconfiguration message for each candidate cell, the question is what is used as a response to the network as an indication of completion.

[0137] In view of this, embodiments of the present disclosure provide a solution for a terminal device to indicate the completion of lower-layer-based mobility. This will be described below in conjunction with Figure 4 for description.

[0138] Figure 4 FIG. shows a schematic diagram illustrating another communication process 400 according to an embodiment of the present disclosure. For the purpose of discussion, process 400 will be described with reference to Figure 1A Process 400 may involve a terminal device 110 and a network device 120 as shown in Figure 1A In this example, the network device 120 serves the terminal device 110.

[0139] As shown in Figure 4 the network device 120 sends 410 to the terminal device 110 a lower-layer signaling indicating a cell handover to a target cell. In some embodiments, the lower-layer signaling may be a MAC CE. In some embodiments, the lower-layer signaling may be a fixed-size MAC CE with zero bits. In some embodiments, the lower-layer signaling may be a DCI.

[0140] Continuing to refer to Figure 4 the terminal device 110 sends 420 to the network device 120 an indication indicating the completion of the cell handover, the indication including information about the target cell.

[0141] In some embodiments, the terminal device 110 may send another low-layer signaling including the indication. In some embodiments, the another low-layer signaling may be a MAC CE. In some embodiments, the another low-layer signaling may be a MAC CE with zero bits of a fixed size. In some embodiments, the another low-layer signaling may be a DCI.

[0142] In some embodiments, the terminal device 110 may send an RRC signaling including the indication. In some embodiments, the RRC signaling may be an RRC reconfiguration complete message.

[0143] In some embodiments, the information of the target cell may include an identifier of the target cell. In some embodiments, the information of the target cell may include an identifier of a configuration of cell handover based on low-layer signaling associated with the target cell. It should be understood that any combination of the above information and any other suitable information is also feasible.

[0144] For illustration, some example embodiments will be described in conjunction with Embodiment 3 and Embodiment 4.

[0145] Embodiment 3

[0146] In this embodiment, the terminal device 110 may send a low-layer signaling including an indication indicating the completion of cell handover. For illustration, it will be described in detail in conjunction with Figure 5A given a detailed description.

[0147] Figure 5A FIG. shows a schematic diagram illustrating an example communication process 500A based on low-layer signaling according to an embodiment of the present disclosure. For the purpose of discussion, reference will be made to Figure 1D describe process 500A. Process 500A may include, as Figure 1D shown, the terminal device 110, the CU 141, and the DUs 151 and 152. In this example, the DU 151 serves the terminal device 110 and acts as the source DU, and the DU 152 does not serve the terminal device 110 and acts as the target DU.

[0148] As Figure 5A shown, the DU 151 sends 510 to the terminal device 110 a low-layer signaling indicating a cell handover to a target cell (e.g., cell 164 of the DU 152). In some embodiments, the low-layer signaling may be a MAC CE. In some embodiments, the low-layer signaling may be a MAC CE with zero bits of a fixed size. In some embodiments, the low-layer signaling may be a DCI.

[0149] Continue to refer to Figure 5A, the terminal device 110 sends another low-layer signaling 520 to the DU 152 indicating the completion of the cell handover. The another low-layer signaling includes information of the target cell. In some embodiments, the another low-layer signaling may be a MAC CE. In some embodiments, the another low-layer signaling may be a fixed-size MAC CE with zero bits. In some embodiments, the another low-layer signaling may be a DCI.

[0150] The DU 152 sends information 530 indicating the completion of the cell handover to the CU 141. The information includes information of the target cell. In some embodiments, the information of the target cell may include an identifier of the target cell. In some embodiments, the information of the target cell may include an identifier of the configuration of the low-layer signaling-based cell handover associated with the target cell. It should be understood that any combination of the above information and any other suitable information is also feasible.

[0151] In this way, the network can know the completion or confirmation of the low-layer-based mobility.

[0152] Embodiment 4

[0153] In this embodiment, the terminal device 110 may send RRC signaling including an indication indicating the completion of the cell handover. For illustration, it will be described in detail in conjunction with Figure 5B given below.

[0154] Figure 5B FIG. shows a schematic diagram illustrating an example communication process 500B based on RRC signaling according to an embodiment of the present disclosure. For the purpose of discussion, process 500B will be described with reference to Figure 1D Process 500B may involve the terminal device 110, the CU 141, and the DUs 151 and 152 as shown in Figure 1D In this example, the DU 151 serves the terminal device 110 and acts as the source DU, and the DU 152 does not serve the terminal device 110 and acts as the target DU.

[0155] As shown in Figure 5B , the DU 151 sends low-layer signaling 540 indicating a cell handover to a target cell (e.g., cell 164 of the DU 152) to the terminal device 110. In some embodiments, the low-layer signaling may be a MAC CE. In some embodiments, the low-layer signaling may be a fixed-size MAC CE with zero bits. In some embodiments, the low-layer signaling may be a DCI.

[0156] Continuing to refer to Figure 5B , the terminal device 110 sends RRC signaling 550 indicating the completion of the cell handover to the CU 141 via the DU 152. That is, the terminal device 110 may send RRC signaling to the DU 152, and the DU 152 may forward the RRC signaling to the CU 141.

[0157] The RRC signaling may include information of the target cell. In some embodiments, the information of the target cell may include an identifier of the target cell. In some embodiments, the information of the target cell may include an identifier of a configuration of cell handover based on lower layer signaling associated with the target cell. It should be understood that any combination of the above information and any other suitable information is also feasible.

[0158] In this way, the network can also be aware of the completion or confirmation of the lower layer-based movement.

[0159] Example implementation of a method

[0160] Therefore, the embodiments of the present disclosure provide communication methods implemented at a terminal device and a network device. The following will refer to Figures 6 to 9 Describe these methods.

[0161] Figure 6 An exemplary communication method 600 implemented at a terminal device according to some embodiments of the present disclosure is shown. For example, method 600 may be executed at a terminal device 110 as shown in Figure 1A For the purpose of discussion, method 600 will be described below with reference to Figure 1A It should be understood that method 600 may include additional blocks not shown and / or some of the shown blocks may be omitted, and the scope of the present disclosure is not limited thereto.

[0162] In block 610, the terminal device 110 receives information associated with cell handover based on lower layer signaling from the network device 120.

[0163] In some embodiments, the terminal device 110 may receive lower layer signaling indicating cell handover, and the lower layer signaling includes first information on whether to perform the set of procedures for cell handover based on lower layer signaling. In some embodiments, the first information may include an indication of whether to perform the set of procedures. In some embodiments, the first information may include an indication of a movement scenario of the cell handover.

[0164] In some embodiments, the terminal device 110 may receive a configuration for a cell handover based on low-layer signaling, the configuration including second information that assists the terminal device in determining whether to perform a set of procedures for the cell handover based on low-layer signaling. In some embodiments, the second information may include an indication of a DU associated with a candidate cell in a set of candidate cells. In some embodiments, the second information may include an indication of whether to perform the set of procedures during a cell handover from one candidate cell in the set of candidate cells to another second candidate cell. In some embodiments, the second information may include an indication of a cell handover from one candidate cell in the set of candidate cells to another candidate cell for which the set of procedures need not be performed. In some embodiments, the second information may include an indication of a cell handover from one candidate cell in the set of candidate cells to another candidate cell for which the set of procedures needs to be performed.

[0165] At block 620, the terminal device 110 determines whether to perform a set of procedures during a cell handover based on low-layer signaling based on the information. The set of procedures includes at least one of the following: packet data convergence protocol recovery for a set of data radio bearers; packet data convergence protocol service data unit discard for a set of signaling radio bearers; radio link control reconstruction for a set of data radio bearers and a set of signaling radio bearers; or media access control reset.

[0166] In some embodiments in which the first information includes an indication of whether to perform the set of procedures, if the indication indicates not to perform the set of procedures, the terminal device 110 may determine not to perform the set of procedures. If the indication indicates to perform the set of procedures, the terminal device 110 may determine to perform the set of procedures.

[0167] In some embodiments in which the first information includes an indication of a handover mobile scenario, if the handover mobile scenario is an in-CU and in-DU scenario, the terminal device 110 may determine not to perform the set of procedures. If the handover mobile scenario is an in-CU and inter-DU scenario, the terminal device 110 may determine to perform the set of procedures.

[0168] In some embodiments, the terminal device 110 may send an indication indicating performance of the set of procedures from a low layer of the terminal device 110 to a high layer of the terminal device 110. The high layer may perform the set of procedures.

[0169] In some embodiments in which the second information includes information on a distributed unit associated with a candidate cell in a set of candidate cells, if the target cell and the source cell are associated with different DUs, the terminal device 110 may determine to perform the set of procedures. If the target cell and the source cell are associated with the same DU, the terminal device 110 may determine not to perform the set of procedures.

[0170] In some embodiments where the second information includes an indication of whether to perform the set of procedures during a cell handover from one candidate cell in the candidate cell set to another second candidate cell, if the set of procedures is to be performed during a cell handover from a source cell to a target cell, the terminal device 110 may determine to perform the set of procedures. If the set of procedures is not to be performed during a cell handover from a source cell to a target cell, the terminal device 110 may determine not to perform the set of procedures.

[0171] In some embodiments where the second information includes an indication of a cell handover from one candidate cell in the candidate cell set to another candidate cell for which the set of procedures need not be performed, if the second information includes an indication of a cell handover from a source cell to a target cell, the terminal device 110 may determine not to perform the set of procedures. If the second information does not include an indication of a cell handover from a source cell to a target cell, the terminal device 110 may determine to perform the set of procedures.

[0172] In some embodiments where the second information includes an indication of a cell handover from one candidate cell in the candidate cell set to another candidate cell for which the set of procedures needs to be performed, if the second information includes an indication of a cell handover from a source cell to a target cell, the terminal device 110 may determine to perform the set of procedures. If the second information does not include an indication of a cell handover from a source cell to a target cell, the terminal device 110 may determine not to perform the set of procedures.

[0173] In some embodiments where a configuration for a cell handover based on low-layer signaling is received, if the configuration does not include the second information, the terminal device may determine to perform the set of procedures.

[0174] Using method 600, the terminal device may determine whether to perform or skip some L2 procedures for a subsequent low-layer based mobility procedure.

[0175] Figure 7 An example method 700 of communication implemented at a terminal device according to some embodiments of the present disclosure is shown. For example, method 700 may be performed at a terminal device 110 as Figure 1A shown. For purposes of discussion, method 700 will be described below with reference to Figure 1A It should be understood that method 700 may include additional blocks not shown and / or some of the shown blocks may be omitted, and the scope of the present disclosure is not limited thereto.

[0176] At block 710, the terminal device 110 receives low-layer signaling from the network device 120 indicating a cell handover to a target cell.

[0177] At block 720, the terminal device 110 sends an indication to the network device 120 indicating the completion of a cell handover, and the indication includes information about the target cell.

[0178] In some embodiments, the terminal device 110 may send another lower-layer signaling including the indication. In some embodiments, the terminal device 110 may send another lower-layer signaling to the DU of the network device 120 associated with the target cell for sending the information about the target cell to the CU of the network device 120.

[0179] In some embodiments, the terminal device 110 may send RRC signaling including the indication. In some embodiments, the terminal device 110 may send RRC signaling to the CU of the network device 120 via the DU of the network device 120 associated with the target cell.

[0180] In some embodiments, the information about the target cell may include at least one of the following: an identifier of the target cell; or an identifier of a configuration of a lower-layer signaling-based cell handover associated with the target cell.

[0181] Using method 700, the network can be aware of the completion or confirmation of a lower-layer-based movement.

[0182] Figure 8 An example communication method 800 implemented at a network device according to some embodiments of the present disclosure is shown. For example, method 800 may be executed at the network device 120 as shown in Figure 1A For the purpose of discussion, method 800 will be described below with reference to Figure 1A It should be understood that method 800 may include additional blocks not shown and / or some of the shown blocks may be omitted, and the scope of the present disclosure is not limited thereto.

[0183] At block 810, the network device 120 sends information associated with a lower-layer signaling-based cell handover to the terminal device 110 for determining whether to execute a set of procedures during the lower-layer signaling-based cell handover. The set of procedures includes at least one of the following: packet data convergence protocol recovery for a data radio bearer set; packet data convergence protocol service data unit discard for a signaling radio bearer set; radio link control reconstruction for a data radio bearer set and a signaling radio bearer set; or medium access control reset.

[0184] In some embodiments, the network device 120 may send lower-layer signaling indicating a cell handover, and the lower-layer signaling includes first information about whether to execute the set of procedures for the lower-layer signaling-based cell handover. In some embodiments, the first information may include at least one of the following: an indication indicating whether to execute the set of procedures; or an indication indicating a movement scenario of the cell handover.

[0185] In some embodiments, the network device 120 may send a configuration for cell handover based on low-layer signaling, and the configuration includes second information for assisting the terminal device in determining whether to execute a set of procedures for cell handover based on low-layer signaling. In some embodiments, the second information may include at least one of the following: information about the distributed unit associated with a candidate cell in the set of candidate cells; an indication of whether to execute the set of procedures during a cell handover from one candidate cell in the set of candidate cells to another second candidate cell; an indication of a cell handover from one candidate cell in the set of candidate cells to another candidate cell that does not require execution of the set of procedures; or an indication of a cell handover from one candidate cell in the set of candidate cells to another candidate cell that requires execution of the set of procedures.

[0186] In some embodiments, the network device 120 may send a configuration for cell handover based on low-layer signaling, and the configuration does not include information associated with cell handover based on low-layer signaling.

[0187] Using method 800, the network device may instruct the terminal device to determine whether to execute or skip some L2 procedures for subsequent low-layer-based mobility procedures.

[0188] Figure 9 An example communication method 900 implemented at a network device according to some embodiments of the present disclosure is shown. For example, method 900 may be executed at the network device 120 as shown in Figure 1A For the purpose of discussion, method 900 will be described below with reference to Figure 1A It should be understood that method 900 may include additional blocks not shown and / or some of the shown blocks may be omitted, and the scope of the present disclosure is not limited thereto.

[0189] In block 910, the network device 120 sends low-layer signaling indicating a cell handover to a target cell to the terminal device 110.

[0190] In block 920, the network device 120 receives an indication indicating the completion of the cell handover from the terminal device 110, and the indication includes information about the target cell.

[0191] In some embodiments, the network device 120 may receive another low-layer signaling including the indication. In some embodiments, the network device 120 may receive another low-layer signaling at the DU of the network device 120 associated with the target cell, and send information indicating the completion of the cell handover including information about the target cell to the CU of the network device 120 at the DU.

[0192] In some embodiments, the network device 120 may receive RRC signaling including the indication. In some embodiments, the network device 120 may receive RRC signaling at the DU of the network device 120, and the DU forwards the RRC signaling to the CU of the network device 120.

[0193] In some embodiments, the information of the target cell includes at least one of the following: the identifier of the target cell; or the identifier of the configuration of cell handover based on lower layer signaling associated with the target cell.

[0194] It should be understood that the operations of methods 600 to 900 are similar to the operations described in conjunction with Figures 2 to 5B Therefore, for the sake of brevity, other details are not repeated here.

[0195] Example implementation of devices and apparatuses

[0196] Figure 10 is a simplified block diagram of the device 1000 suitable for implementing the embodiments of the present disclosure. The device 1000 may be considered as the terminal device 110 or the network device 120 as shown in Figure 1A or another exemplary implementation of the CU 141, DU 151 or DU 152 as shown in Figure 1D Therefore, the device 1000 may be implemented at the terminal device 110 or the network device 120 or the CU 141 or the DU 151 or 152, or implemented as at least a part of the terminal device 110 or the network device 120 or the CU 141 or the DU 151 or 152.

[0197] As shown in the figure, the device 1000 includes 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 1010 stores at least a part of the program 1030. The TX / RX 1040 is used for two-way communication. The TX / RX 1040 has at least one antenna to facilitate communication, but in fact, the access nodes mentioned in this application may have several antennas. The communication interface may represent any interface required for communicating with other network elements, such as the X2 / Xn interface for two-way communication between eNB / gNB, the S1 / NG interface for communication between the mobility management entity (MME) / access and mobility management function (AMF) / SGW / UPF and eNB / gNB, the Un interface for communication between eNB / gNB and the relay node (RN), or the Uu interface for communication between eNB / gNB and the terminal device.

[0198] Assume that program 1030 includes program instructions that, when executed by an associated processor 1010, enable device 1000 to operate in accordance with embodiments of the present disclosure, as discussed herein. Embodiments herein can be implemented by computer software executable by processor 1010 of device 1000, or by hardware, or by a combination of software and hardware. Processor 1010 can be configured to implement various embodiments of the present invention. In addition, the combination of processor 1010 and memory 1020 can form a processing component 1050 suitable for implementing various embodiments of the present disclosure. Figures 2 to 9 Memory 1020 can be of any type suitable for a local technology network and can be implemented using any suitable data storage technology, by way of non-limiting example, such as a non-transitory computer-readable storage medium, 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 device 1000, there can be several physically distinct memory modules in device 1000. By way of non-limiting example, processor 1010 can be of any type suitable for a local technology network and can include 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. Device 1000 can have multiple processors, such as an application-specific integrated circuit chip that is subordinate in time to a clock synchronized with a main processor.

[0199] In some embodiments, the terminal device includes circuitry configured to: receive information associated with a low-layer signaling-based cell handover from a network device; and determine, based on the information, whether to execute a set of procedures during the low-layer signaling-based cell handover, the set of procedures including at least one of the following: packet data convergence protocol recovery for a set of data radio bearers; packet data convergence protocol service data unit discard for a set of signaling radio bearers; radio link control reconstruction for a set of data radio bearers and a set of signaling radio bearers; or media access control reset.

[0200] In some embodiments, the terminal device includes circuitry configured to: receive low-layer signaling indicating a cell handover to a target cell from a network device; and send an indication to the network device indicating completion of the cell handover, the indication including information about the target cell.

[0201]

[0202] ​In some embodiments, a network device includes circuitry configured to: send to a terminal device information associated with a low-layer-signaling-based cell handover for determining whether to perform a set of procedures during the low-layer-signaling-based cell handover, the set of procedures including at least one of the following: packet data convergence protocol recovery for a set of data radio bearers; packet data convergence protocol service data unit discard for a set of signaling radio bearers; radio link control reconstruction for a set of data radio bearers and a set of signaling radio bearers; or media access control reset.

[0203] In some embodiments, a network device includes circuitry configured to: send to a terminal device low-layer signaling indicating a cell handover to a target cell; and receive from the terminal device an indication indicating completion of the cell handover, the indication including information about the target cell.

[0204] As used herein, the term "circuitry" may refer to hardware circuitry and / or a combination of hardware circuitry and software. For example, circuitry may be a combination of analog and / or digital hardware circuitry and software / firmware. As another example, circuitry may be any portion of a hardware processor with software, including a digital signal processor, software, and memory that work together to cause a device such as a terminal device or a network device to perform various functions. In yet another example, circuitry may be a hardware circuit and / or a processor, such as a microprocessor or a portion of a microprocessor, that requires software / firmware for operation, but the software may be absent when not required for operation. As used herein, the term circuitry also encompasses implementations that are only hardware circuits or processors or portions of hardware circuits or processors and their (or their) accompanying software and / or firmware.

[0205] Generally speaking, embodiments of the present disclosure may provide the following solutions.

[0206] In one solution, a communication method includes: at a terminal device, receiving from a network device information associated with a low-layer-signaling-based cell handover; and determining, based on the information, whether to perform a set of procedures during the low-layer-signaling-based cell handover, the set of procedures including at least one of the following: packet data convergence protocol recovery for a set of data radio bearers; packet data convergence protocol service data unit discard for a set of signaling radio bearers; radio link control reconstruction for a set of data radio bearers and a set of signaling radio bearers; or media access control reset.

[0207] In some embodiments, receiving the information includes: at the terminal device, receiving from the network device low-layer signaling indicating a cell handover, the low-layer signaling including first information about whether to perform the set of procedures for the low-layer-signaling-based cell handover.

[0208] In some embodiments, the first information includes an indication specifying whether to execute the set of processes. In these embodiments, determining whether to execute the set of processes includes: determining not to execute the set of processes based on determining that the indication specifies not to execute the set of processes; or determining to execute the set of processes based on determining that the indication specifies to execute the set of processes.

[0209] In some embodiments, the first information includes an indication specifying the mobile scenario of the cell handover. In these embodiments, determining whether to execute the set of processes includes: determining not to execute the set of processes based on determining that the mobile scenario of the cell handover is within the central unit and within the distributed unit; or determining to execute the set of processes based on determining that the mobile scenario of the cell handover is within the central unit and between distributed units.

[0210] In some embodiments, the method further includes: sending, from a lower layer of the terminal device to a higher layer of the terminal device, an indication specifying to execute the set of processes; and executing the set of processes by the higher layer.

[0211] In some embodiments, receiving the information includes: at the terminal device, receiving, from the network device, a configuration for the low-layer-signaling-based cell handover, the configuration including second information that assists the terminal device in determining whether to execute the set of processes for the low-layer-signaling-based cell handover.

[0212] In some embodiments, the second information includes information about the distributed unit associated with a candidate cell in a set of candidate cells. In these embodiments, determining whether to execute the set of processes includes: determining to execute the set of processes based on determining that the target cell and the source cell are associated with different distributed units; or determining not to execute the set of processes based on determining that the target cell and the source cell are associated with the same distributed unit.

[0213] In some embodiments, the second information includes an indication of whether to execute the set of processes during a cell handover from one candidate cell in a set of candidate cells to another second candidate cell. In these embodiments, determining whether to execute the set of processes includes: determining to execute the set of processes based on determining that the set of processes is to be executed during a cell handover from the source cell to the target cell; or determining not to execute the set of processes based on determining that the set of processes is not to be executed during a cell handover from the source cell to the target cell.

[0214] In some embodiments, the second information includes an indication of a cell handover from one candidate cell to another candidate cell in the candidate cell set that does not require the execution of the process set. In these embodiments, determining whether to execute the process set includes: determining not to execute the process set based on determining that the second information includes an indication of a cell handover from a source cell to a target cell; or determining to execute the process set based on determining that the second information does not include an indication of a cell handover from a source cell to a target cell.

[0215] In some embodiments, the second information includes an indication of a cell handover from one candidate cell to another candidate cell in the candidate cell set that requires the execution of the process set. In these embodiments, determining whether to execute the process set includes: determining to execute the process set based on determining that the second information includes an indication of a cell handover from a source cell to a target cell; or determining not to execute the process set based on determining that the second information does not include an indication of a cell handover from a source cell to a target cell.

[0216] In some embodiments, receiving the information further includes: at the terminal device, receiving a configuration for the low-layer signaling-based cell handover from the network device. In some embodiments, determining whether to execute the process set includes: determining to execute the process set based on determining that the configuration does not include the second information.

[0217] In another aspect, a communication method includes: at a terminal device, receiving low-layer signaling indicating a cell handover to a target cell from a network device; and sending an indication to the network device indicating the completion of the cell handover, the indication including information about the target cell.

[0218] In some embodiments, sending the indication includes: sending another low-layer signaling including the indication; or sending radio resource control signaling including the indication.

[0219] In some embodiments, sending the another low-layer signaling includes: sending the another low-layer signaling to a distributed unit of the network device associated with the target cell for sending information about the target cell to a central unit of the network device.

[0220] In some embodiments, sending the radio resource control signaling includes: sending the radio resource control signaling to a central unit of the network device via a distributed unit of the network device associated with the target cell.

[0221] In some embodiments, the information about the target cell includes at least one of the following: an identifier of the target cell; or an identifier of a configuration for low-layer signaling-based cell handover associated with the target cell.

[0222] In another solution, a communication method includes: at a network device, sending information associated with a low-layer signaling-based cell handover to a terminal device for determining whether to perform the set of procedures during the low-layer signaling-based cell handover, the set of procedures including at least one of the following: packet data convergence protocol recovery for a set of data radio bearers; packet data convergence protocol service data unit discard for a set of signaling radio bearers; radio link control re-establishment for a set of data radio bearers and a set of signaling radio bearers; or media access control reset.

[0223] In some embodiments, sending the information includes: sending low-layer signaling indicating a cell handover, the low-layer signaling including first information on whether to perform the set of procedures for the low-layer signaling-based cell handover.

[0224] In some embodiments, the first information includes at least one of the following: an indication indicating whether to perform the set of procedures; or an indication indicating the mobile scenario of the cell handover.

[0225] In some embodiments, sending the information includes: sending a configuration for the low-layer signaling-based cell handover, the configuration including second information assisting the terminal device in determining whether to perform the set of procedures for the low-layer signaling-based cell handover.

[0226] In some embodiments, the second information includes at least one of the following: information on a distributed unit associated with a candidate cell in a set of candidate cells; an indication of whether to perform the set of procedures during a cell handover from one candidate cell in the set of candidate cells to another second candidate cell; an indication of a cell handover from one candidate cell in the set of candidate cells to another candidate cell that does not require performing the set of procedures; or an indication of a cell handover from one candidate cell in the set of candidate cells to another candidate cell that requires performing the set of procedures.

[0227] In some embodiments, sending the information further includes: sending a configuration for the low-layer signaling-based cell handover, the configuration not including information associated with the low-layer signaling-based cell handover.

[0228] In another solution, a communication method includes: at a network device, sending low-layer signaling indicating a cell handover to a target cell to the terminal device; and receiving, from the terminal device, an indication indicating completion of the cell handover, the indication including information on the target cell.

[0229] In some embodiments, receiving the indication includes: receiving another lower-layer signaling including the indication; or receiving radio resource control signaling including the indication.

[0230] In some embodiments, receiving the another lower-layer signaling includes: receiving the another lower-layer signaling at a distributed unit of the network device associated with the target cell; and sending, at the distributed unit, information indicating completion of the cell handover to a central unit of the network device, the information including information about the target cell.

[0231] In some embodiments, receiving the radio resource control signaling includes: receiving the radio resource control signaling at a distributed unit of the network device; and forwarding, by the distributed unit, the radio resource control signaling to a central unit of the network device.

[0232] In some embodiments, the information about the target cell includes at least one of the following: an identifier of the target cell; or an identifier of a configuration of a lower-layer-signaling-based cell handover associated with the target cell.

[0233] In another aspect, a communication device includes: a processor configured to cause the device to perform any of the methods described above.

[0234] In general, the various embodiments of the present disclosure may be implemented using hardware or a specific circuit, software, logic, or any combination thereof. Some aspects may be implemented using hardware, while other aspects may be implemented using firmware or software, which may be executed by a controller, a microprocessor, or other computing devices. Although aspects of the embodiments of the present disclosure are shown and described as block diagrams, flowcharts, or using some other graphical representation, it will be understood that the blocks, devices, systems, techniques, or methods described herein may be implemented in hardware, software, firmware, a specific circuit or logic, general hardware or a controller, or other computing devices, or some combination thereof, as non-limiting examples.

[0235] 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 those included in program modules, which are executed in a device on a target real or virtual processor to perform the above-referred Figures 2 to 9The described processes or methods. Generally speaking, program modules include routines, programs, libraries, objects, classes, components, data structures, etc. that perform specific tasks or implement specific abstract data types. The functions of program modules can be combined or separated among program modules as needed in various embodiments. The machine-executable instructions of program modules can be executed within local or distributed devices. In a distributed device, program modules can be located in both local storage media and remote storage media.

[0236] The program code for performing the methods of the present disclosure can be written in any combination of one or more programming languages. This program code can be provided to a processor or controller of a general-purpose computer, a special-purpose computer, or other programmable data processing device, such that the program code, when executed by the processor or controller, implements the functions / operations specified in the flowchart and / or block diagram. The program code can be executed entirely on the machine, partially on the machine, as a stand-alone software package, partially on the machine and partially on a remote machine, or entirely on a remote machine or server.

[0237] The above program code can be contained on a machine-readable medium, which can be any tangible medium that can contain or store a program used by or in conjunction with an instruction execution system, apparatus, or device. The machine-readable medium can be a machine-readable signal medium or a machine-readable storage medium. The machine-readable medium can include, but is not limited to, electrical, magnetic, optical, electromagnetic, infrared, or semiconductor systems, apparatus, or devices, or any suitable combination of the foregoing. More specific examples of the machine-readable storage medium will include an electrical connection having one or more wires, a portable computer disk, 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.

[0238] Furthermore, although the operations are described in a specific order, this should not be construed as requiring that the operations be performed in the specific order shown or in sequential order, or that all of the illustrated operations be performed to achieve the desired result. In some cases, multitasking and parallel processing may be advantageous. Similarly, although several specific implementation details are included in the above discussion, these details should not be construed as limiting the scope of the present disclosure, but rather as describing features specific to particular embodiments. Certain features described in the context of separate embodiments can also be implemented in combination in a single embodiment. Conversely, the various features described in the context of a single embodiment can also be implemented separately or in any suitable sub-combination in multiple embodiments.

[0239] Although the present disclosure has been described in terms of language specific to structural features and / or method acts, it is to be understood that the disclosure defined in the appended claims is not necessarily limited to the specific features or acts described above. On the contrary, the above specific features and acts are disclosed as example forms of implementing the claims.

Claims

1. A communication method, comprising: at a terminal device, receiving information associated with a low-layer signaling-based cell handover from a network device; and based on the information, determining whether to execute a set of procedures during the low-layer signaling-based cell handover, the set of procedures including at least one of the following: Packet Data Convergence Protocol (PDCP) recovery for a set of data radio bearers; PDCP service data unit discard for a set of signaling radio bearers; Radio Link Control (RLC) reconstruction for a set of data radio bearers and a set of signaling radio bearers; or Media Access Control (MAC) reset.

2. The method according to claim 1, wherein receiving the information comprises: at the terminal device, receiving low-layer signaling indicating a cell handover from the network device, the low-layer signaling including: first information on whether to execute the set of procedures for the low-layer signaling-based cell handover.

3. The method according to claim 2, wherein the first information includes an indication indicating whether to execute the set of procedures, and wherein determining whether to execute the set of procedures comprises: determining not to execute the set of procedures according to a determination that the indication indicates that the set of procedures will not be executed; or determining to execute the set of procedures according to a determination that the indication indicates that the set of procedures will be executed.

4. The method according to claim 2, wherein the first information includes an indication indicating a mobile scenario of the cell handover, and wherein determining whether to execute the set of procedures comprises: determining not to execute the set of procedures according to a determination that the mobile scenario of the cell handover is within a central unit and within a distributed unit scenario; or determining to execute the set of procedures according to a determination that the mobile scenario of the cell handover is within a central unit and between distributed unit scenarios.

5. The method according to claim 2, further comprising: sending an indication indicating the execution of the set of procedures from a lower layer of the terminal device to an upper layer of the terminal device; and executing the set of procedures by the upper layer.

6. The method according to claim 1, wherein receiving the information comprises: at the terminal device, receiving a configuration for the low-layer signaling-based cell handover from the network device, the configuration including second information that assists the terminal device in determining whether to execute the set of procedures for the low-layer signaling-based cell handover.

7. The method according to claim 6, wherein the second information includes information on a distributed unit associated with a candidate cell in a set of candidate cells, and wherein determining whether to execute the set of procedures comprises: determining to execute the set of procedures according to a determination that a target cell and a source cell are associated with different distributed units; or determining not to execute the set of procedures according to a determination that a target cell and a source cell are associated with the same distributed unit.

8. The method according to claim 6, wherein the second information includes an indication of whether the set of procedures is executed during a cell handover from one candidate cell in a set of candidate cells to another second candidate cell, and wherein determining whether to execute the set of procedures comprises: Determine to execute the set of procedures according to the determination that the set of procedures is executed during a cell handover from a source cell to a target cell; or Determine not to execute the set of procedures according to the determination that the set of procedures is not executed during a cell handover from a source cell to a target cell.

9. The method according to claim 6, wherein the second information includes an indication of a cell handover from one candidate cell to another candidate cell in the set of candidate cells for which the set of procedures does not need to be executed, and wherein determining whether to execute the set of procedures comprises: Determine not to execute the set of procedures according to the determination that the second information includes an indication of a cell handover from a source cell to a target cell; or Determine to execute the set of procedures according to the determination that the second information does not include an indication of a cell handover from a source cell to a target cell.

10. The method according to claim 6, wherein the second information includes an indication of a cell handover from one candidate cell to another candidate cell in the set of candidate cells for which the set of procedures needs to be executed, and wherein determining whether to execute the set of procedures comprises: Determine to execute the set of procedures according to the determination that the second information includes an indication of a cell handover from a source cell to a target cell; or Determine not to execute the set of procedures according to the determination that the second information does not include an indication of a cell handover from a source cell to a target cell.

11. The method according to claim 6, wherein receiving the information further comprises: At the terminal device, receive a configuration for the cell handover based on low-layer signaling from the network device; and wherein determining whether to execute the set of procedures includes: determining to execute the set of procedures according to the determination that the configuration does not include the second information.

12. A communication method, comprising: At the terminal device, receive low-layer signaling indicating a cell handover to a target cell from a network device; and Send an indication indicating the completion of the cell handover to the network device, the indication including information about the target cell.

13. The method according to claim 12, wherein sending the indication comprises: Send another low-layer signaling including the indication; or Send radio resource control signaling including the indication.

14. The method according to claim 13, wherein sending the another low-layer signaling comprises: Send the another low-layer signaling to a distributed unit of the network device associated with the target cell for sending information about the target cell to a central unit of the network device.

15. The method according to claim 13, wherein sending the radio resource control signaling comprises: Send the radio resource control signaling to a central unit of the network device via a distributed unit of the network device associated with the target cell.

16. The method according to claim 12, wherein the information about the target cell includes at least one of the following: An identifier of the target cell; or An identifier of a configuration for cell handover based on low-layer signaling associated with the target cell.

17. A communication device, comprising: A processor, configured to cause the device to perform the method according to any one of claims 1 to 11, or any one of claims 12 to 16.

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