Method performed by terminal device, method performed by network device, terminal device and network device

Abstract

[0001] In one aspect, a terminal device receives a DCI triggering an RA procedure for a candidate cell among a set of candidate cells that enable LTM, and performs the RA procedure for the candidate cell. The terminal device then transmits information for the RA procedure, the information including at least one of identity information of the candidate cell or an index of a candidate configuration associated with the candidate cell. In this manner, optimization of LTM deployment can be facilitated.

Description

[Technical Field]

[0001] Embodiments of the present disclosure relate generally to the field of telecommunications, and more particularly to communication devices and methods for self-organizing network (SON) enhancements for layer 1 (L1) / layer 2 (L2) triggered mobility (LTM). [Background technology]

[0002] As is known, SON was introduced to support system deployment and performance optimization. To improve network performance, the mobility robustness optimization (MRO) function of SON needs to be further enhanced to support mobility enhancement.

[0003] Currently, it is proposed to trigger the change, addition or release of the serving cell by lower layer signaling, such as L1 / L2 signaling, also called LTM. However, the SON enhancements for LTM are still incomplete and need to be further developed. Summary of the Invention [Means for solving the problem]

[0004] Generally, embodiments of the present disclosure provide communication methods, devices, and computer storage media for SON enhancements for LTM.

[0005] In a first aspect, a terminal device is provided, the terminal device including a processor configured to cause the terminal device to receive downlink control information triggering a random access procedure to a candidate cell of a set of candidate cells that enable LTM, to perform the random access procedure to the candidate cell, and to transmit information of the random access procedure including at least one of identity information of the candidate cell or an index of a candidate configuration associated with the candidate cell.

[0006] In a second aspect, a terminal device is provided, the terminal device including a processor configured to cause the terminal device to receive a configuration of a set of candidate cells that enable LTM, and, according to a determination that a cell switch or radio link failure has occurred during the LTM, to transmit information of the cell switch or radio link failure.

[0007] In a third aspect, a terminal device is provided, the terminal device including a processor configured to cause the terminal device to receive a medium access control control element indicating a cell switch to a target candidate cell, to perform the cell switch to the target candidate cell, and, according to a determination that the cell switch has been successfully completed, to transmit information of the cell switch.

[0008] In a fourth aspect, there is provided a method of communication, the method including: receiving, at a terminal device, downlink control information triggering a random access procedure to a candidate cell of a set of LTM-enabled candidate cells, performing the random access procedure to the candidate cell, and transmitting information of the random access procedure including at least one of an identity of the candidate cell or an index of a candidate configuration associated with the candidate cell.

[0009] In a fifth aspect, there is provided a method of communication, the method including: receiving, at a terminal device, a configuration of a set of candidate cells that enable LTM; and, according to a determination that a cell switch or radio link failure has occurred during the LTM, transmitting information of the cell switch or radio link failure.

[0010] In a sixth aspect, there is provided a method of communication, the method including: receiving, at a terminal device, a medium access control control element indicating a cell switch to a target candidate cell; performing the cell switch to the target candidate cell; and, according to a determination that the cell switch is successfully completed, transmitting information of the cell switch.

[0011] In a seventh aspect, there is provided a computer-readable medium having instructions stored thereon that, when executed by at least one processor, cause the at least one processor to perform a method according to any of the fourth to sixth aspects of the present disclosure.

[0012] Other features of the present disclosure will become readily apparent from the following description.

[0013] The above and other objects, features and advantages of the present disclosure will become more apparent through more detailed descriptions of several embodiments of the present disclosure in the accompanying drawings. [Brief explanation of the drawings]

[0014] [Figure 1A] 1 illustrates an exemplary communication network in which some embodiments of the present disclosure may be implemented. [Figure 1B] 1 illustrates a schematic diagram illustrating network protocol layer entities that may be established for a user plane (UP) protocol stack in a device, according to some embodiments of the present disclosure. [Figure 1C]1 illustrates a schematic diagram illustrating network protocol layer entities that may be established for a control plane (CP) protocol stack in a device, according to some embodiments of the present disclosure. [Figure 1D] FIG. 1 shows a schematic diagram illustrating the process of LTM, in which some embodiments of the present disclosure may be implemented. [Figure 2] 1 illustrates a schematic diagram illustrating a process for reporting information of a random access (RA) procedure for a candidate cell according to an embodiment of the present disclosure. [Figure 3] FIG. 1 shows a schematic diagram illustrating a process for reporting impairments during LTM according to an embodiment of the present disclosure. [Figure 4] 1 shows a schematic diagram illustrating reported time information according to an embodiment of the present disclosure; [Figure 5] FIG. 1 shows a schematic diagram illustrating a process for reporting a successful cell switch during LTM according to an embodiment of the present disclosure. [Figure 6] 1 illustrates an exemplary method of communication implemented in a terminal device, according to some embodiments of the present disclosure. [Figure 7] 1 illustrates another exemplary method of communication implemented in a terminal device, according to some embodiments of the present disclosure. [Figure 8] 10 illustrates yet another exemplary method of communication implemented in a terminal device, according to some embodiments of the present disclosure. [Figure 9] FIG. 1 is a simplified block diagram of a device suitable for practicing embodiments of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0015] Throughout the drawings, the same or similar reference numbers represent the same or similar elements.

[0016] The principles of the present disclosure will now be described with reference to several embodiments. It should be understood that these embodiments are set forth for illustrative purposes only, without implying any limitation on the scope of the present disclosure, and to facilitate those skilled in the art in understanding and practicing the present disclosure. The present disclosure described herein can be implemented in various ways other than those described below.

[0017] In the following description and claims, unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs.

[0018] As used herein, the term "terminal device" refers to any device that has wireless or wired communication capabilities. Examples of terminal devices include user equipment (UE), personal computers, desktops, mobile phones, mobile phones, smartphones, personal digital assistants (PDAs), portable computers, tablets, wearable devices, Internet of Things (IoT) devices, Ultra-reliable and Low Latency Communications (URLLC) devices, Internet of Everything (IoE) devices, machine type communication (MTC) devices, in-vehicle devices for V2X communications (where X means pedestrian, vehicle, or infrastructure / network), Integrated Access and Backhaul (IAB) devices, spacecraft or aircraft in a Non-terrestrial network (NTN) including High Altitude Platforms (HAPs) including satellites and Unmanned Aircraft Systems (UASs), Augmented Reality (AR), Mixed Reality (MR), and other technologies. Examples of such devices include, but are not limited to, extended reality (XR) devices, which include different types of reality such as real reality (VR) and virtual reality (VR), unmanned aerial vehicles (UAVs), which are aircraft that do not require a human pilot, commonly known as drones, devices on high speed trains (HSTs), imaging devices such as digital cameras, sensors, gaming devices, music storage and playback devices, or internet devices that enable wireless / wired internet access and browsing.A "terminal device" may further have "multicast / broadcast" capabilities to support public safety and mission-critical V2X applications, transparent IPv4 / IPv6 multicast distribution, IPTV, smart TV, wireless services, over-the-air software distribution, group communication, and IoT applications. It may also incorporate one or more SIMs, known as multi-SIM Subscriber Identity Modules (SIMs). The term "terminal device" may be used interchangeably with UE, mobile station, subscriber station, mobile terminal, user terminal, or wireless device.

[0019] The term "network device" refers to a device that can provide or host a cell or coverage area through which terminal devices can communicate. Examples of network devices include, but are not limited to, a Node B (NodeB or NB), evolved Node B (eNodeB or eNB), next generation Node B (gNB), transmission reception point (TRP), remote radio unit (RRU), radio head (RH), remote radio head (RRH), IAB node, low power node such as femto node, pico node, reconfigurable intelligent surface (RIS), etc.

[0020] A terminal device or a network device may have artificial intelligence (AI) or machine learning capabilities. The terminal device or the network device generally includes a model that is trained from a large amount of collected data for a specific function and can be used to predict some information.

[0021] The terminal or network device may operate in 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 Terahertz (THz). It may also operate in licensed, unlicensed, or shared spectrum. The terminal device may have multiple connections with network devices under Multi-Radio Dual Connectivity (MR-DC) application scenarios. The terminal device or network device may operate in full duplex, flexible duplex, and cross-division duplex modes.

[0022] Embodiments of the present disclosure may 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.

[0023] In one embodiment, a terminal device may be connected with a first network device and a second network device. One of the first network device and the second network device may be a master node, and the other may be a secondary node. The first network device and the second network device may use different radio access technologies (RATs). In one embodiment, the first network device may be a first RAT device, and the second network device may be a second RAT device. In one embodiment, the first RAT device is an eNB, and the second RAT device is a gNB. Information related to the different RATs may be transmitted to the terminal device from at least one of the first network device or the second network device. In one embodiment, the first information may be transmitted from the first network device to the terminal device, and the second information may be transmitted from the second network device directly or via the first network device to the terminal device. In one embodiment, information related to a configuration of the terminal device configured by the second network device may be transmitted from the second network device via the first network device. Information related to the reconfiguration of the terminal device configured by the second network device may be transmitted to the terminal device directly from the second network device or via the first network device.

[0024] As used herein, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly dictates otherwise. The term "comprises" and variations thereof should be read as open terms meaning "including, but not limited to." The term "based on" should be read as "based at least in part on." The terms "one embodiment" and "an embodiment" should be read as "at least one embodiment." The term "another embodiment" should be read as "at least one other embodiment." Terms such as "first," "second," etc. may refer to different or the same object. Other definitions, both express and implied, may be included below.

[0025] In some instances, values, procedures, or devices are referred to as "best," "lowest," "highest," "minimum," "maximum," etc. It should be understood that such descriptions are intended to indicate that a selection can be made from among many functional alternatives used, and that such a selection is not necessarily better, less, higher, or otherwise preferred than other selections.

[0026] In the context of the present disclosure, the term "cell switch" may be used interchangeably with "synchronous reconfiguration for a secondary cell group (SCG) or master cell group (MCG)" or "cell change." The term "PSCell" refers to an SpCell of an SCG, the term "PCell" refers to an SpCell of an MCG, and the term "SpCell" refers to a primary cell of an SCG or MCG. The term "SCell" refers to a secondary cell. The term "lower layer signaling" may be used interchangeably with "L1 / L2 signaling." The term "radio resource control (RRC) reconfiguration" may be used interchangeably with "RRC reconfiguration message." The term "candidate cell" may be used interchangeably with "LTM candidate cell." The term "target cell" may be used interchangeably with "target candidate cell," "candidate target cell," or "LTM target candidate cell."

[0027] SON encompasses network auto-configuration and auto-optimization solutions and was introduced to support system deployment and performance optimization.

[0028] While the SON functions physical cell identity (PCI) allocation and automatic neighbor relations (ANR) were already introduced in 3GPP Release 8, the term "SON" was introduced in 3GPP Release 9. The success of these two functions encouraged further research on this topic, resulting in three available SON functions: mobility robustness optimization (MRO), mobility load balancing (MLB), and random access channel (RACH) optimization. The MRO and MLB functions were further enhanced in subsequent releases to address the increasing complexity of long-term evolution (LTE). In addition to ANR, MRO, MLB, and RACH optimization, other functions enabling specific aspects of network automation are also discussed. These SON functions are implemented based on statistics of a large amount of data from the network and user equipment (UE), which can be considered a precursor to the use of big data in the radio access network (RAN).

[0029] To improve network performance, SON MRO functions need to be further enhanced in addition to supporting enhanced mobility.

[0030] Embodiments of the present disclosure provide a communication solution for enhancing SON for at least LTM. In one aspect, a terminal device receives downlink control information (DCI) that triggers an RA procedure for a candidate cell among a set of candidate cells that enable LTM. The terminal device performs the RA procedure for the candidate cell and transmits information of the RA procedure. In some embodiments, the information of the random access procedure may include at least one of identity information of the candidate cell or an index of a candidate configuration associated with the candidate cell. In this way, information of unsuccessful or successful RA for an LTM candidate cell may be reported to the network, and SON functionality may be enhanced for the network to optimize LTM deployment.

[0031] In another aspect, a terminal device receives a configuration of a set of candidate cells that enable LTM. If a cell switch or radio link failure occurs during LTM, the terminal device transmits information of the cell switch or radio link failure. In this way, information of failure during LTM can be reported to the network, and SON functionality can be enhanced for the network to optimize LTM deployment.

[0032] In yet another aspect, the terminal device receives a medium access control element (MAC CE) indicating a cell switch to the target candidate cell, and performs the cell switch to the target candidate cell. If the cell switch is successfully completed, the terminal device transmits information of the cell switch. In this way, information of the successful cell switch during LTM can be reported to the network, and the SON function can be enhanced for the network to optimize the LTM deployment.

[0033] The principles and implementations of the present disclosure are explained in detail below with reference to the drawings.

[0034] Communication Network Example 1A shows a schematic diagram of an example communication network 100A in which some embodiments of the present disclosure may be implemented. As shown in FIG. 1A, communication network 100A may include a terminal device 110 and a network device 120. Network device 120 provides multiple cells (shown as cells 121 and 122) to serve the terminal device.

[0035] 1A is provided for illustrative purposes without implying any limitations on the present disclosure. Communications network 100A may include any suitable number of network devices, and / or terminal devices, and / or cells adapted to perform implementations of the present disclosure.

[0036] 1A, terminal device 110 may communicate with network device 120 via a channel, such as a wireless communication channel. Communications in communication network 100A may conform to any suitable standard, including, but not limited to, Global System for Mobile Communications (GSM), Long Term Evolution (LTE), LTE Evolution, LTE Advanced, New Radio (NR), Wideband Code Division Multiple Access (WCDMA), Code Division Multiple Access (CDMA), GSM EDGE Radio Access Network (GERAN), Machine Type Communications (MTC), etc. Embodiments of the present disclosure may be implemented in accordance with any generation of communication protocols now known or developed in the future. Examples of communication protocols include, but are not limited to, first generation (1G), second generation (2G), 2.5G, 2.75G, third generation (3G), fourth generation (4G), 4.5G, fifth generation (5G) communication protocols, 5.5G, 5G-Advanced networks, or sixth generation (6G) networks.

[0037] Communication in the direction from terminal device 110 to network device 120 is called uplink (UL) communication, and communication in the reverse direction from network device 120 to terminal device 110 is called downlink (DL) communication. Terminal device 110 may move between cells of network device 120 and possibly other network devices. In UL communication, terminal device 110 may transmit UL data and control information to network device 120 over a UL channel. In DL communication, network device 120 may transmit DL data and control information to terminal device 110 over a DL channel.

[0038] Communications in the communication network 100A may occur according to a UP protocol stack and a CP protocol stack. Generally speaking, for a communication device (such as a terminal device or a network device), there may be multiple entities for multiple network protocol layers in the protocol stack, which may be configured to perform corresponding processing on data or signaling transmitted from and received by the communication device. FIG. 1B shows a schematic diagram 100B illustrating network protocol layer entities that may be established for a UP protocol stack in a device according to some embodiments of the present disclosure. As shown in FIG. 1B, in UP, each of the terminal device 110 and the network device 120 may include an L1 layer entity, i.e., a physical (PHY) layer entity (also referred to as a PHY entity), and one or more entities at higher layers (L2 and Layer 3 (L3) or higher). The one or more entities in the higher layer may include a medium access control (MAC) layer entity (also referred to as a MAC entity), a radio link control (RLC) layer entity (also referred to as an RLC entity), a packet data convergence protocol (PDCP) layer entity (also referred to as a PDCP entity), and a service data application protocol (SDAP) layer entity (also referred to as an SDAP entity, which will be established in 5G and later generation networks). In some cases, the PHY, MAC, RLC, PDCP, and SDAP entities are stacked.

[0039] FIG. 1C shows a schematic diagram 100C illustrating network protocol layer entities that may be established for a CP protocol stack in a device in accordance with some embodiments of the present disclosure. As shown in FIG. 1C, in a CP, each of the terminal device 110 and the network device 120 may include an L1 layer entity, i.e., a PHY layer entity (also referred to as a PHY entity), and one or more entities of higher layers (L2 and L3 layers). The one or more entities of the higher layers may include a MAC layer entity (also referred to as a MAC entity), an RLC layer entity (also referred to as an RLC entity), a PDCP layer entity (also referred to as a PDCP entity), and a radio resource control (RRC) layer entity (also referred to as an RRC entity). The RRC layer may also be referred to as an access stratum (AS) layer, and thus, an RRC entity may also be referred to as an AS entity. As shown in FIG. 1C, the terminal device 110 may also include a non-access stratum (NAS) layer entity (also referred to as a NAS entity). The NAS layer on the network side is not located in a network device but in a core network (CN, not shown). In some cases, these entities form a stack structure.

[0040] In the context of this disclosure, L1 refers to the PHY layer, L2 refers to the MAC layer, or the RLC layer, or the PDCP layer, or the SDAP layer, and L3 refers to the RRC layer. In the context of this disclosure, L1 or L2 may also be collectively referred to as a lower layer, and L3 may also be referred to as an upper layer. Thus, L1 or L2 signaling may also be referred to as lower layer signaling, and L3 signaling may also be referred to as upper layer signaling.

[0041] Generally, communication channels are classified into logical channels, transport channels, and physical channels. Physical channels are channels through which the PHY layer actually transmits information. For example, physical channels may include a physical uplink control channel (PUCCH), a physical uplink shared channel (PUSCH), a physical random-access channel (PRACH), a PDCCH, a physical downlink shared channel (PDSCH), and a physical broadcast channel (PBCH).

[0042] A transmission channel is a channel between the PHY layer and the MAC layer, and may include, for example, a broadcast channel (BCH), a downlink shared channel (DL-SCH), a paging channel (PCH), an uplink shared channel (UL-SCH), and a random access channel (RACH).

[0043] Logical channels are channels between the MAC layer and the RLC layer, and may include, for example, a dedicated control channel (DCCH), a common control channel (CCCH), a paging control channel (PCCH), a broadcast control channel (BCCH), and a dedicated traffic channel (DTCH).

[0044] Generally, a channel between the RRC layer and the PDCP layer is called 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 may be defined in the RRC layer: SRB0, SRB1, SRB2, and SRB3. SRB0 uses the CCCH for establishing or re-establishing an RRC connection. SRB1 uses the DCCH and is established when an RRC connection is established. SRB2 uses the DCCH and is established during RRC reconfiguration and after initial security activation. SRB3 uses the DCCH and is established between the terminal device 110 and the SN when a dual connection is established.

[0045] 1A , in some embodiments, terminal device 110 may be located within the coverage of cell 121 of network device 120, and terminal device 110 may communicate with network device 120 based on a network configuration. In this case, cell 121 may be referred to as a serving cell of terminal device 110. Cell 122 may be referred to as an LTM candidate cell of terminal device 110.

[0046] In some embodiments, terminal device 110 may establish a dual connection (i.e., a simultaneous connection) with network device 120 and another network device (not shown). In some embodiments, network device 120 may function as a master node (MN). In these embodiments, terminal device 110 may communicate with network device 120 via a set of serving cells. The set of serving cells forms an MCG, and a primary cell in the MCG is referred to as a PCell. In some scenarios, the PCell may change from cell 121 to cell 122, which is referred to as a handover (HO). In some embodiments, network device 120 may function as a secondary node (SN). In these embodiments, the set of serving cells provided by network device 120 forms an SCG, and a primary cell in the SCG is referred to as a PSCell. In some scenarios, the PSCell may change from cell 121 to cell 122, which is referred to as a PSCell change.

[0047] In some scenarios, network device 120 may receive an L1 measurement report from terminal device 110. Based on the L1 measurement report, network device 120 may change the serving cell of terminal device 110 through a MAC CE. This procedure is called LTM. Network device 120 may prepare one or more candidate cells and provide the candidate cell configurations to terminal device 110 via an RRC message. An LTM cell switch is then triggered by network device 120 by selecting one of the candidate cell configurations as a target configuration for LTM.

[0048] The cell switch trigger information may be carried in a MAC CE including at least a candidate configuration index. Cell-specific radio bearer and measurement configurations may be part of the LTM candidate cell configuration. The terminal device 110 may perform contention-based random access (CBRA) or contention-free random access (CFRA) in cell switch. If the terminal device 110 does not need to acquire TA of the target cell during cell switch, the terminal device 110 may also skip the RA procedure. RACH resources for CFRA may be provided in the RRC configuration.

[0049] 1D shows a schematic diagram illustrating a process 100D of LTM in which some embodiments of the present disclosure may be implemented. For discussion purposes, process 100D will be described with reference to FIG. 1A. Process 100D may involve terminal device 110 and network device 120 shown in FIG. 1A. Network device 120 may be an MN or SN serving terminal device 110. In this example, network device 120 provides a serving cell to terminal device 110 and also provides one or more candidate cells to terminal device 110.

[0050] 1D , in the LTM preparation phase, terminal device 110 may send a measurement report message to network device 120 (140). Network device 120 may decide to use LTM (141) and begin preparing for LTM candidate status. Network device 120 may send an RRC reconfiguration message to terminal device 110 (142) that includes configurations of one or more LTM candidate target cells. Terminal device 110 may store the configurations of the LTM candidate target cells and send an RRC reconfiguration complete message to network device 120 (143).

[0051] In an early synchronization (i.e., early sync) phase, terminal device 110 may perform DL synchronization and timing advance (TA) acquisition with a candidate target cell before receiving the LTM cell switch command (144).

[0052] In the LTM execution phase, terminal device 110 may perform L1 measurements on the configured LTM candidate target cell and transmit a lower layer measurement report to network device 120 (145). Network device 120 may decide to perform an LTM cell switch to the target cell (146) and transmit a MAC CE triggering the LTM cell switch by including the candidate configuration index of the target cell (147). Terminal device 110 may switch to the configuration of the LTM candidate target cell (148). If a TA is not available, terminal device 110 may perform an RA procedure toward the target cell (149).

[0053] In the LTM completion phase, terminal device 110 may indicate successful completion of the LTM cell switch toward the target cell (150).

[0054] Embodiments of the present disclosure provide communication solutions for enhancing SON over LTM, the details of which are described with reference to FIGS.

[0055] Example implementation of reporting of non-normal RA for TA acquisition In some scenarios, the terminal device 110 may perform an RA procedure for TA acquisition of a candidate cell before a cell switch command is received. Conventionally, if an RA problem is indicated from a lower layer, the terminal device may assume that a radio link failure (RLF) is detected for the corresponding cell group. However, with an RA procedure triggered for one LTM candidate cell for early TA acquisition, the conventional behavior is no longer appropriate because the LTM candidate cell is still not an SpCell.

[0056] In view of the above, an embodiment of the present disclosure provides a solution for reporting information of an RA procedure for a candidate cell, which is described below in relation to FIG.

[0057] 2 shows a schematic diagram illustrating a process 200 of communications for reporting information of an RA procedure for a candidate cell, according to an embodiment of the present disclosure. For discussion purposes, the process 200 will be described with reference to FIG. 1A. The process 200 may involve the terminal device 110 and the network device 120 shown in FIG. 1A. In this example, the network device 120 provides a serving cell (e.g., cell 121) to the terminal device 110 and also provides one or more candidate cells to the terminal device 110. The serving cell may be an SpCell, PCell, or PSCell of the terminal device 110.

[0058] 2, network device 120 may transmit 210 a DCI to terminal device 110 that triggers an RA procedure for a candidate cell in a set of candidate cells that enable LTM. Upon receiving the DCI, terminal device 110 may perform 220 an RA procedure for the candidate cell. In some embodiments, the RA procedure may fail. In some embodiments, the RA procedure may complete successfully.

[0059] Referring to FIG. 2, terminal device 110 may transmit information of the RA procedure to network device 120 (230).

[0060] In some embodiments, the terminal device 110 may transmit information of the RA procedure via a MAC CE. If uplink shared channel (UL-SCH) resources are available for a new transmission and the UL-SCH resources can correspond to the MAC CE and its subheader, the MAC layer may instruct the multiplexing and assembly procedure to generate a MAC CE. Otherwise, the MAC layer may trigger a scheduling request for the MAC CE. In some embodiments, the MAC layer of the terminal device 110 does not indicate an RA problem to upper layers (e.g., the RRC layer) of the terminal device 110.

[0061] In some embodiments, terminal device 110 may transmit information of the RA procedure via an RRC message. In some embodiments, the MAC layer may indicate an RA problem associated with the LTM candidate cell to a higher layer (e.g., the RRC layer). In some embodiments, terminal device 110 may transmit information of the RA procedure via UEAssistanceInformation or any other suitable message that exists or is developed in the future.

[0062] In some embodiments, the terminal device 110 may transmit information of the RA procedure via uplink control information (UCI).

[0063] Regarding the transmission of information of the RA procedure, some exemplary embodiments will be described in relation to the following first to third embodiments.

[0064] Embodiment 1 In this embodiment, the RA procedure fails. The terminal device may transmit RA procedure information as an indication of the RA procedure failure. In some embodiments, if the preamble transmission counter is equal to the maximum number of random access preamble transmissions plus one (i.e., PREAMBLE_TRANSMISSION_COUNTER=preambleTransMax+1), the terminal device 110 may consider the RA procedure not to have been completed successfully and may transmit RA procedure information to the network device 120. In some embodiments, the RA procedure information may include at least one of an identity of the LTM candidate cell or a candidate configuration index associated with the LTM candidate cell.

[0065] For illustrative purposes, an exemplary procedure can be described as follows: Before receiving the LTM cell switch command, the UE receives a PDCCH triggering an RA procedure to one LTM candidate cell for TA acquisition, and then performs an RA to the LTM candidate cell. During the RA procedure, if the preamble transmission counter is equal to the maximum number of random access preamble transmissions plus one (PREAMBLE_TRANSMISSION_COUNTER=preambleTransMax+1), the UE shall at least one of: send RA problem information to the network towards the LTM candidate cell, consider the RA procedure not to have been completed successfully, or not consider RLF detected for the corresponding cell group (i.e., MCG or SCG).

[0066] In some embodiments, the information of the RA procedure may include an identification of the candidate cell. In some embodiments, the information of the RA procedure may include an index of a candidate configuration associated with the candidate cell. It should be understood that any combination of the above information and any other suitable information may also be possible.

[0067] In this way, the UE behavior in case of non-normal RA to LTM candidate cells is defined and the SON functionality is enhanced for the network to optimize LTM deployment.

[0068] Embodiment 2 In this embodiment, the RA procedure is completed successfully and is contention-based. The terminal device may receive an UL grant for transmission to the candidate cell as contention resolution. In this case, the terminal device may discard or ignore the UL grant.

[0069] For illustrative purposes, an exemplary procedure can be described as follows: If the RA to the LTM candidate cell is contention-based and for contention resolution, the UE receives a PDCCH transmission addressed to the C-RNTI and containing an UL grant for a new transmission, Consider this conflict resolution successful, Stop the ra-ContentionResolutionTimer, Destroys the TEMPORARY_C-RNTI, Discard / ignore any UL grants received, This random access procedure shall be considered to have been completed successfully.

[0070] In this way, there is no need to transmit any data to the LTM candidate cell.

[0071] Embodiment 3 In this embodiment, when the random access procedure for one LTM candidate cell for TA acquisition is completed successfully or unsuccessfully, the terminal device 110 stores and transmits information about the RA procedure, including information about the success or failure of the RA procedure.

[0072] In some embodiments, the RA procedure information may include an identification of the candidate cell. In some embodiments, the RA procedure information may include an index of a candidate configuration associated with the candidate cell. In some embodiments, the RA procedure information may include an identification of a serving cell (e.g., SpCell) of the terminal device 110 when the RA procedure for the LTM candidate cell is triggered. In some embodiments, the RA procedure information may include an indication of the success or failure of the RA procedure. It should be understood that any combination of the above information and any other suitable information may also be possible.

[0073] In some embodiments, the terminal device 110 may store information of the RA procedure in an RA report (e.g., a VarRA-report). In some embodiments, the terminal device 110 may store information of the RA procedure in a dedicated UE variable for RA to the LTM candidate cell. It should be understood that any other suitable method is also possible.

[0074] In some embodiments, the terminal device 110 may transmit an indication indicating the availability of information for an RA procedure to the network device 120 if there is such stored information.

[0075] In some embodiments, network device 120 may send a request to obtain information of an RA procedure to terminal device 110. In some embodiments, network device 120 may request information of an RA procedure associated with at least one LTM candidate cell from terminal device 110 by sending a UEInformationRequest message with a request indication for information of an RA procedure associated with at least one LTM candidate cell. Terminal device 110 may then send the information of the RA procedure to network device 120 via a UEInformationResponse message.

[0076] In some embodiments, the terminal device 110 may transmit information of the RA procedure in an RA report with an RA purpose indicating early acquisition of a TA value. In other words, when the RA procedure is completed successfully or unsuccessfully for one LTM candidate cell for TA acquisition, the terminal device 110 may set or include an RA purpose indicating early TA acquisition of the LTM in the RA report.

[0077] So far, a solution has been described for reporting information of RA procedures for LTM candidate cells. In this way, information of RA procedures for LTM candidate cells can be reported to the network, which can facilitate optimization of LTM deployment.

[0078] Example Implementation of Reporting Faults in LTM For SON enhancements for LTM, embodiments of the present disclosure also provide a solution for reporting failures during LTM, which is described below in connection with FIG.

[0079] 3 shows a schematic diagram illustrating a process 300 for reporting a failure during LTM according to an embodiment of the present disclosure. For discussion purposes, the process 300 will be described with reference to FIG. 1A. The process 300 may involve the terminal device 110 and the network device 120 shown in FIG. 1A. In this example, the network device 120 provides a serving cell (e.g., cell 121) to the terminal device 110 and also provides a target candidate cell (e.g., cell 122) to the terminal device 110. The serving cell may be an SPCell, PCell, or PSCell of the terminal device 110.

[0080] As shown in FIG. 3, network device 120 may transmit 310 to terminal device 110 a configuration of a set of candidate cells that enable LTM.

[0081] Upon determining that a cell switch failure (which may also be referred to as a handover failure) or an RLF has occurred during LTM, terminal device 110 may transmit 320 information of the cell switch failure or RLF to network device 120. In some embodiments, terminal device 110 may start a timer upon the LTM cell switch. When the timer expires, terminal device 110 may determine that a cell switch failure has occurred.

[0082] In some embodiments, upon a cell switch failure or RLF, terminal device 110 may store or configure information about the cell switch failure or RLF and report the information about the cell switch failure or RLF to network device 120. In some embodiments, terminal device 110 may store the information about the cell switch failure or RLF in an RLF report. In some embodiments, terminal device 110 may store and transmit the information about the cell switch failure or RLF in an SCGFailureInformation message. It should be understood that any other suitable method is also possible.

[0083] In some embodiments, the cell switch failure or RLF information may include an indication that the handover type is LTM. In some embodiments, the cell switch failure or RLF information may include an indication of whether the failed cell switch is a subsequent cell switch. In some embodiments, the cell switch failure or RLF information may include neighbor cell measurement results with an indication of whether the neighbor cell is a candidate cell of a set of candidate cells. In some embodiments, the cell switch failure or RLF information may include a list of identities of candidate cells for LTM at the time of the cell switch failure or RLF. In some embodiments, the cell switch failure or RLF information may include an indication of whether an RA procedure is skipped.

[0084] In some embodiments where a cell switch failure occurs, the cell switch failure information may include the elapsed time from receipt of the configuration to initiation of the cell switch, i.e., the elapsed time from receipt of the most recent LTM configuration to initiation of the last LTM cell switch or receipt of a cell switch command (i.e., MAC CE) towards the target cell. Figure 4 shows a schematic diagram 400 illustrating reported time information according to an embodiment of the present disclosure. As shown in Figure 4, reference numeral 410 denotes the elapsed time from receipt of the configuration to initiation of the cell switch.

[0085] In some embodiments where a cell switch failure occurs, the cell switch failure information may include the elapsed time from the initiation of the cell switch to the cell switch failure, i.e., the elapsed time from the receipt of the cell switch command (i.e., MAC CE) towards the target cell to the cell switch failure. As shown in Figure 4, reference numeral 420 denotes the elapsed time from the initiation of the cell switch to the cell switch failure.

[0086] In some embodiments where an RLF occurs, the RLF information may include the elapsed time from receipt of the configuration to the RLF, i.e., the elapsed time from receipt of the most recent conditional reconfiguration while connected to the source PCell or PSCell to the RLF. As shown in Figure 4, reference numeral 430 denotes the elapsed time from receipt of the configuration to the RLF.

[0087] It should be understood that any combination of the above information with any other suitable information may also be possible.

[0088] So far, a solution for reporting fault information during LTM has been described. In this way, cell switching fault and RLF information can be reported to the network, which can facilitate optimization of LTM deployment.

[0089] Example Implementation of Successful Cell Switch Reporting For SON enhancements for LTM, embodiments of the present disclosure also provide a solution for reporting successful cell switching during LTM, which is described below in connection with FIG.

[0090] 5 shows a schematic diagram illustrating a process 500 for reporting a successful cell switch during LTM according to an embodiment of the present disclosure. For discussion purposes, process 500 will be described with reference to FIG. 1A. Process 500 may involve terminal device 110 and network device 120 shown in FIG. 1A. In this example, network device 120 provides a serving cell (e.g., cell 121) to terminal device 110 and also provides a target candidate cell (e.g., cell 122) to terminal device 110. The serving cell may be an SPCell, PCell, or PSCell of terminal device 110.

[0091] 5, the network device 120 may transmit 510 a MAC CE indicating a cell switch to the target candidate cell to the terminal device 110. Upon receiving the MAC CE, the terminal device 110 may perform 520 a cell switch to the target candidate cell.

[0092] Upon determining that the cell switch has been successfully completed, terminal device 110 may transmit 530 information of the cell switch.

[0093] In some embodiments, upon successful completion of the cell switch, the terminal device 110 may store or configure information about the cell switch and report the information about the cell switch to the network device 120. In some embodiments, the terminal device 110 may store the information about the cell switch in a successful handover report (SHR). In some embodiments, the terminal device 110 may store the information about the cell switch in a successful PSCell change / addition report (SPR). It should be understood that any other suitable method is also possible.

[0094] In some embodiments, the cell switch information may include an indication that the handover type is LTM. In some embodiments, the cell switch information may include an indication of whether the cell switch is a subsequent cell switch. In some embodiments, the cell switch information may include an indication of whether an RA procedure is skipped. In some embodiments, the cell switch information may include measurement results of a neighboring cell with an indication of whether the neighboring cell is a candidate cell for LTM.

[0095] In some embodiments, the cell switch information may include the elapsed time from receiving the configuration of the set of candidate cells that enable LTM to the initiation of the cell switch, i.e., the elapsed time from receiving the latest LTM configuration for the target cell to the initiation of the cell switch or the receipt of a cell switch command (i.e., MAC CE) towards the target cell. Continuing with reference to Figure 4, reference numeral 440 denotes the elapsed time from receiving the configuration of the set of candidate cells that enable LTM to the initiation of the cell switch.

[0096] In some embodiments, the cell switch information may include the elapsed time from receipt of the MAC CE to successful completion of the cell switch. Continuing with reference to Figure 4, reference numeral 450 denotes the elapsed time from receipt of the MAC CE to successful completion of the cell switch.

[0097] It should be understood that any combination of the above information with any other suitable information may also be possible.

[0098] So far, a solution has been described for reporting information of successful cell switches during LTM, in this way information of successful cell switches can be reported to the network, which can facilitate optimization of LTM deployment.

[0099] It should be understood that the processes 200, 300 and 500 described in connection with Figures 2-5 may be performed separately or in any suitable combination.

[0100] Exemplary implementation of the method In response to the above, embodiments of the present disclosure provide methods of communication implemented in a terminal device, which are described below with reference to Figures 6 to 8.

[0101] 6 illustrates an exemplary method 600 of communication implemented in a terminal device, according to some embodiments of the present disclosure. For example, method 600 may be implemented in terminal device 110 as shown in FIG. 1A. For purposes of discussion, method 600 is described below with reference to FIG. 1A. It should be understood that method 600 may include additional blocks not shown and / or omit some blocks that are shown, and that the scope of the present disclosure is not limited in this respect.

[0102] In block 610, the terminal device 110 receives a DCI that triggers an RA procedure for a candidate cell from a set of candidate cells that enable LTM.

[0103] In block 620, the terminal device 110 performs an RA procedure with the candidate cell.

[0104] In block 630, the terminal device 110 transmits information of the RA procedure. In some embodiments, the information of the RA procedure may include at least one of an identification of the candidate cell or an index of a candidate configuration associated with the candidate cell. In some embodiments, the information of the RA procedure may further include at least one of an identification of a serving cell of the terminal device 110 when the RA procedure was triggered for the candidate cell or an indication of the success or failure of the RA procedure.

[0105] In some embodiments, if the RA procedure fails, the terminal device 110 may transmit information of the RA procedure as an indication of the failure of the RA procedure.

[0106] In some embodiments, the terminal device 110 may transmit information of the RA procedure via a MAC CE. In some embodiments, the terminal device 110 may transmit information of the RA procedure via an RRC message. In some embodiments, the terminal device 110 may transmit information of the RA procedure via a UCI.

[0107] In some embodiments, terminal device 110 may store information of the RA procedure. In some embodiments, terminal device 110 may transmit an indication indicating availability of information of the RA procedure. In some embodiments, terminal device 110 may receive a request to obtain information of the RA procedure.

[0108] In some embodiments, the terminal device 110 may transmit information of the RA procedure in an RA report with an RA purpose indicating early acquisition of a TA value.

[0109] In some embodiments where the RA procedure is contention-based, terminal device 110 may receive an UL grant for transmission to a candidate cell and discard the UL grant as contention resolution.

[0110] Using method 600, information of RA procedures for LTM candidate cells may be reported to the network, which may facilitate optimization of LTM deployment.

[0111] 7 illustrates another exemplary method 700 of communication implemented in a terminal device, according to some embodiments of the present disclosure. For example, method 700 may be implemented in terminal device 110 as shown in FIG. 1A. For purposes of discussion, method 700 is described below with reference to FIG. 1A. It should be understood that method 700 may include additional blocks not shown and / or omit some blocks that are shown, and that the scope of the present disclosure is not limited in this respect.

[0112] In block 710, the terminal device 110 receives a configuration of a set of candidate cells that enable LTM.

[0113] In block 720, the terminal device 110 determines that a cell switch or radio link failure occurred during the LTM.

[0114] In block 730, the terminal device 110 transmits information of the cell switch or radio link failure.

[0115] In some embodiments, the cell switch or radio link failure information may include at least one of an indication that the handover type is LTM, an indication of whether the failed cell switch is a subsequent cell switch, measurement results of the neighboring cell with an indication of whether the neighboring cell is a candidate cell of a set of candidate cells, a list of identities of candidate cells for LTM at the time of the failure, an indication of whether the RA procedure is skipped, the elapsed time from receipt of the configuration to initiation of the cell switch, the elapsed time from initiation of the cell switch to failure of the cell switch or the elapsed time from receipt of the configuration to failure of the radio link.

[0116] Using method 700, information of failures during LTM may be reported to the network, which may facilitate optimization of LTM deployment.

[0117] 8 illustrates yet another exemplary method 800 of communication implemented in a terminal device, in accordance with some embodiments of the present disclosure. For example, method 800 may be implemented in terminal device 110 as shown in FIG. 1A. For purposes of discussion, method 800 is described below with reference to FIG. 1A. It should be understood that method 800 may include additional blocks not shown and / or omit some blocks that are shown, and that the scope of the present disclosure is not limited in this respect.

[0118] In block 810, the terminal device 110 receives a MAC CE from the network device 120 indicating a cell switch to the target candidate cell.

[0119] In block 820, the terminal device 110 performs a cell switch to the target candidate cell.

[0120] In block 830, the terminal device 110 determines that the cell switch was completed successfully.

[0121] In block 840, the terminal device 110 transmits information of the cell switch.

[0122] In some embodiments, the cell switch information may include at least one of an indication that the handover type is LTM, an indication of whether the cell switch is a subsequent cell switch, an indication of whether the RA procedure is skipped, measurement results of the neighboring cell with an indication of whether the neighboring cell is a candidate cell for LTM, the elapsed time from receiving the configuration of the set of candidate cells that allows LTM to initiating the cell switch, or the elapsed time from receiving the MAC CE to successful completion of the cell switch.

[0123] In some embodiments, terminal device 110 may store cell switching information.

[0124] Using method 800, information of successful cell switches during LTM may be reported to the network, which may facilitate optimization of LTM deployment.

[0125] It should be understood that the operations of methods 600-800 correspond to those described in connection with FIGS. 2-5, and therefore other details will not be repeated here for the sake of brevity.

[0126] Exemplary Implementations of Devices and Apparatus 9 is a simplified block diagram of a device 900 suitable for implementing embodiments of the present disclosure. Device 900 may be considered a further exemplary implementation of terminal device 110 or network device 120 shown in FIG. 1. Thus, device 900 may be implemented in or at least as part of terminal device 110 or network device 120.

[0127] As shown, device 900 includes a processor 910, a memory 920 coupled to the processor 910, a suitable transmitter (TX) and receiver (RX) 940 coupled to the processor 910, and a communication interface coupled to the TX / RX 940. The memory 910 stores at least a portion of a program 930. The TX / RX 940 is for bidirectional communication. The TX / RX 940 has at least one antenna to facilitate communication, although in practice the access nodes described in this application may have several antennas. The communication interface may represent any interface required for communication with other network elements, such as an X2 / Xn interface for bidirectional communication between eNBs / gNBs, an S1 / NG interface for communication between a Mobility Management Entity (MME) / Access and Mobility Management Function (AMF) / SGW / UPF and an eNB / gNB, an Un interface for communication between an eNB / gNB and a relay node (RN), or a Uu interface for communication between an eNB / gNB and a terminal device.

[0128] The program 930 is assumed to include program instructions that, when executed by an associated processor 910, cause the device 900 to operate according to embodiments of the present disclosure, as discussed herein with reference to FIGS. 1A-8. The embodiments herein may be implemented by computer software executable by the processor 910 of the device 900, or by hardware, or a combination of software and hardware. The processor 910 may be configured to implement various embodiments of the present disclosure. Furthermore, the combination of the processor 910 and the memory 920 may form a processing means 950 adapted to implement various embodiments of the present disclosure.

[0129] Memory 920 may be of any type suitable for a local technology network and may be implemented using any suitable data storage technology, such as, by way of non-limiting example, non-transitory computer-readable storage media, semiconductor-based memory devices, magnetic memory devices and systems, optical memory devices and systems, fixed memory, and removable memory. While only one memory 920 is shown in device 900, several physically distinct memory modules may be present within device 900. Processor 910 may be of any type suitable for a local technology network and may include, by way of non-limiting example, one or more of a general-purpose computer, a special-purpose computer, a microprocessor, a digital signal processor (DSP), and a processor based on a multi-core processor architecture. Device 900 may have multiple processors, such as application-specific integrated circuit chips that are time-slaved to a clock that synchronizes the main processor.

[0130] In some embodiments, the terminal device includes circuitry configured to receive downlink control information that triggers a random access procedure for a candidate cell from a set of candidate cells that enable Layer 1 or Layer 2 triggered mobility, perform the random access procedure for the candidate cell, and transmit information for the random access procedure that includes at least one of an identification information of the candidate cell or an index of a candidate configuration associated with the candidate cell.

[0131] In some embodiments, the terminal device includes circuitry configured to receive a configuration of a set of candidate cells that enable Layer 1 or Layer 2 triggered mobility, and, pursuant to a determination that a cell switch or radio link failure has occurred during the Layer 1 or Layer 2 triggered mobility, transmit information of the cell switch or radio link failure.

[0132] In some embodiments, the terminal device includes circuitry configured to receive a medium access control control element indicating a cell switch to a target candidate cell, perform a cell switch to the target candidate cell, and, pursuant to a determination that the cell switch has been successfully completed, transmit information about the cell switch.

[0133] As used herein, the term "circuit" may refer to a hardware circuit and / or a combination of a hardware circuit and software. For example, a circuit may be a combination of analog and / or digital hardware circuitry and software / firmware. As a further example, a circuit may be any portion of a hardware processor having software, including a digital signal processor, software, and memory, that cooperate to cause an apparatus, such as a terminal device or a network device, to perform various functions. In yet a further example, a circuit may be a hardware circuit and / or processor, e.g., a microprocessor or part of a microprocessor, that requires software / firmware for operation, but where software is not required for operation, the software may not be present. As used herein, the term circuit also encompasses merely a hardware circuit or processor or part of a hardware circuit or processor and its (or their) accompanying software and / or firmware implementation.

[0134] In general, various embodiments of the present disclosure may be implemented in hardware or special-purpose circuits, software, logic, or any combination thereof. Some aspects may be implemented in hardware, while other aspects may be implemented in firmware or software that may be executed by a controller, microprocessor, or other computing device. While various aspects of the embodiments of the present disclosure are illustrated and described as block diagrams, flowcharts, or using some other graphical representations, it should be understood that the blocks, apparatus, systems, techniques, or methods described herein may be implemented in, by way of non-limiting example, hardware, software, firmware, special-purpose circuits or logic, general-purpose hardware or controller, or other computing device, or some combination thereof.

[0135] 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, that execute on a target real or virtual processor device to implement a process or method such as those described above with reference to FIGS. 1A-8. Generally, program modules include routines, programs, libraries, objects, classes, components, data structures, etc. that perform particular tasks or implement particular abstract data types. The functionality of the program modules may be combined or split between program modules as desired in various embodiments. The machine-executable instructions of a program module may be executed in a local or distributed device. In a distributed device, program modules may be located in both local and remote storage media.

[0136] Program code for implementing the methods of the present disclosure may be written in any combination of one or more programming languages. These program codes may be provided to a processor or controller of a general-purpose computer, a special-purpose computer, or other programmable data processing apparatus, so that when executed by the processor or controller, the program code causes the processor or controller to perform the functions / acts specified in the flowcharts and / or block diagrams. The program code may run 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.

[0137] The above program code may be embodied in a machine-readable medium, which may be any tangible medium that can contain or store a program used by or in connection with an instruction execution system, apparatus, or device. The machine-readable medium may be a machine-readable signal medium or a machine-readable storage medium. Examples of machine-readable media include, but are not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, apparatus, or devices, or any suitable combination of the foregoing. More specific examples of machine-readable storage media include electrical connections with one or more wires, portable computer diskettes, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fibers, portable compact disc read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination of the foregoing.

[0138] Furthermore, while operations are shown in a particular order, this should not be understood as requiring that such operations be performed in the particular order or sequential order shown, or that all of the shown operations be performed, to achieve desirable results. In certain situations, multitasking and parallel processing may be advantageous. Similarly, while details of several specific implementations are included in the above discussion, these should not be construed as limitations on the scope of the disclosure, but rather as descriptions of features that may be specific to particular embodiments. Certain features that are described in the context of separate embodiments may also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment may also be implemented in multiple embodiments separately or in any suitable subcombination.

[0139] Although the present disclosure has been described in language specific to structural features and / or methodological acts, it is to be understood that the present disclosure, as defined in the appended claims, is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims.

Claims

1. A terminal device, The terminal device, receiving downlink control information that triggers a random access procedure to a candidate cell from a set of candidate cells that enable Layer 1 or Layer 2 triggered mobility; performing the random access procedure to the candidate cell; the identity of the candidate cell; or an index of a candidate configuration associated with said candidate cell; transmitting information of the random access procedure, including at least one of a processor configured to cause Terminal devices, including:

2. 2. The terminal device of claim 1, wherein the terminal device is configured to transmit the information of the random access procedure according to a determination that the random access procedure has failed by transmitting the information of the random access procedure as an indication of the failure of the random access procedure.

3. transmitting said information of said random access procedure via a medium access control control element; transmitting the information of the random access procedure via a radio resource control message; or transmitting the information of the random access procedure via uplink control information; The terminal device according to claim 1 , wherein the terminal device is adapted to transmit the information of the random access procedure by at least one of the following:

4. The information of the random access procedure includes: the identity of the serving cell of the terminal device when the random access procedure is triggered; or an indication of the success or failure of said random access procedure; The terminal device of claim 1 , further comprising at least one of:

5. storing the information of the random access procedure; sending an indication of the availability of said information for said random access procedure; or receiving a request to obtain the information of the random access procedure; The terminal device according to claim 4 , further adapted to perform at least one of the following:

6. 5. The terminal device of claim 4, wherein the information of the random access procedure is transmitted by transmitting the information of the random access procedure in a random access report having a random access purpose indicating early acquisition of a timing advance value.

7. The random access procedure is contention-based, and the terminal device: receiving an uplink grant for transmission to the candidate cell as contention resolution; discarding the uplink grant; The terminal device of claim 1 , further adapted to:

8. A terminal device, The terminal device, receiving a configuration of a set of candidate cells that enable Layer 1 or Layer 2 triggered mobility; transmitting information of the cell switch or the radio link failure according to a determination that a cell switch or a radio link failure has occurred during the Layer 1 or Layer 2 triggered mobility; a processor configured to cause Terminal devices, including:

9. The information on the cell switching or the failure of the radio link, an indication that the handover type is the Layer 1 or Layer 2 triggered mobility; an indication of whether the failed cell switch is a subsequent cell switch; Measurement results of the neighboring cell, the measurement results having an indication of whether the neighboring cell is a candidate cell of the set of candidate cells; a list of identities of candidate cells for the Layer 1 or Layer 2 triggered mobility at the time of the failure; an indication of whether the random access procedure is skipped; the elapsed time from receiving the configuration to initiating the cell switch; the elapsed time from the initiation of the cell switch to the failure of the cell switch; or the time elapsed between the receipt of the configuration and the failure of the wireless link; The terminal device of claim 8, comprising at least one of:

10. A terminal device, The terminal device, receiving a medium access control control element indicating a cell switch to a target candidate cell; performing the cell switch to the target candidate cell; transmitting information about the cell switch according to a determination that the cell switch has been successfully completed; a processor configured to cause Terminal devices, including:

11. The information of the cell switching an indication that the handover type is Layer 1 or Layer 2 triggered mobility; an indication of whether the cell switch is a subsequent cell switch; an indication of whether the random access procedure is skipped; Measurement results of the neighboring cell, the measurement results having an indication of whether the neighboring cell is a candidate cell for Layer 1 or Layer 2 triggered mobility; the time elapsed between receiving the configuration of the set of candidate cells enabling the Layer 1 or Layer 2 triggered mobility and the initiation of the cell switch; or the time elapsed from receipt of the medium access control control element to successful completion of the cell switch; The terminal device of claim 10, comprising at least one of:

12. The terminal device according to claim 10, further adapted to store the information of the cell switch.

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