Beam indication of layer 1 / layer 2 triggered mobility (LTM)

Abstract

Apparatus and methods for beam indication for Layer 1 / Layer 2 triggered mobility (LTM) are disclosed. Advantages of the apparatus / method include reduction of cell handover latency. In one aspect, a user equipment device (UE) receives a Media Access Control Control Element (MAC-CE) from a serving cell, the MAC-CE including a candidate cell and an indication of activation of one or more Transmission Configuration Indicator (TCI) states for the candidate cell. The UE also receives a cell handover command from the serving cell via low layer signaling, the cell handover command indicating the candidate cell as the target cell. The UE also switches communication with the serving cell to communication with the target cell in response to the cell handover command, wherein communication with the target cell includes communicating with the target cell by applying at least one TCI state of the one or more TCI states.

Description

TECHNICAL FIELD

[0001] Various example embodiments relate generally to wireless networks, and more particularly to beam indication for layer 1 / layer 2 triggered mobility (LTM) in wireless networks. BACKGROUND

[0002] Wireless networks provide significant advantages for user mobility. The ability for users to stay connected while moving provides advantages not only to the users, but also to society as a whole with higher efficiency and productivity. As users have higher and higher expectations for connection reliability, data speeds, and device battery life, wireless network technology must keep pace with such expectations. As a result, there is an ongoing interest in improving wireless network technology. SUMMARY

[0003] According to aspects of the present disclosure, a user equipment apparatus includes at least one processor and at least one memory. The at least one memory stores instructions that, when executed by the at least one processor, cause the user equipment apparatus to at least: receive, from a serving cell, a medium access control control element (MAC-CE) including: a candidate cell and an indication of activation of one or more transmission configuration indicator (TCI) states for the candidate cell; receive, from the serving cell via low layer signaling, a cell switch command indicating the candidate cell as a target cell; and in response to the cell switch command, switch communication with the serving cell to communication with the target cell, wherein the communication with the target cell includes communicating with the target cell by applying at least one of the one or more TCI states.

[0004] In one aspect of the present disclosure, the MAC-CE can include: a first field; and a second field to indicate whether information in the first field is for the serving cell or for the candidate cell.

[0005] In one aspect of the present disclosure, the MAC-CE can include: a first value; and a second value to indicate that the first value identifies the candidate cell.

[0006] In one aspect of the present disclosure, the MAC-CE can include a candidate cell specific TCI state list including the one or more TCI states.

[0007] In one aspect of the present disclosure, the cell switch command can further include: a reference to at least one of the one or more TCI states.

[0008] In an aspect of the disclosure, the instructions, when executed by the at least one processor, can further cause the user equipment apparatus to receive the cell switch command at least by receiving a downlink control information (DCI) including an indication of a candidate cell and a TCI codepoint referencing at least one TCI state of one or more TCI states.

[0009] In an aspect of the disclosure, the instructions, when executed by the at least one processor, can further cause the user equipment apparatus to receive the cell switch command at least by receiving a downlink control information (DCI) including an indication of a candidate cell activation TCI list including a candidate cell and a TCI codepoint referencing at least one TCI state of one or more TCI states.

[0010] In an aspect of the disclosure, the instructions, when executed by the at least one processor, can further cause the user equipment apparatus to receive the cell switch command at least by receiving a downlink control information (DCI) including an indication of a candidate cell activation TCI list including a candidate cell and a TCI codepoint referencing at least one TCI state of one or more TCI states.

[0011] In an aspect of the disclosure, the instructions, when executed by the at least one processor, can further cause the user equipment apparatus to receive the cell switch command at least by receiving a downlink control information (DCI) including an indication of a candidate cell activation TCI list including a candidate cell and a TCI codepoint referencing at least one TCI state of one or more TCI states.

[0012] In an aspect of the disclosure, the instructions, when executed by the at least one processor, can further cause the user equipment apparatus to receive the cell switch command at least by receiving a downlink control information (DCI) including an indication of a candidate cell activation TCI list including a candidate cell and a TCI codepoint referencing at least one TCI state of one or more TCI states.

[0013] In an aspect of the disclosure, the instructions, when executed by the at least one processor, can further cause the user equipment apparatus to receive the cell switch command at least by receiving a downlink control information (DCI) including an indication of a candidate cell activation TCI list including a candidate cell and a TCI codepoint referencing at least one TCI state of one or more TCI states.

[0014] In an aspect of the disclosure, the instructions, when executed by the at least one processor, can further cause the user equipment apparatus to receive the cell switch command at least by receiving a downlink control information (DCI) including an indication of a candidate cell activation TCI list including a candidate cell and a TCI codepoint referencing at least one TCI state of one or more TCI states.

[0015] According to an aspect of the disclosure, a method performed by a user equipment device. The method includes: receiving, from a serving cell, a medium access control control element (MAC-CE) including: an indication of a candidate cell and one or more transmission configuration indicator (TCI) states being activated for the candidate cell; receiving, from the serving cell via low layer signaling, a cell switch command indicating the candidate cell as a target cell; and in response to the cell switch command, switching communication with the serving cell to communication with the target cell, wherein the communication with the target cell includes communicating with the target cell by applying at least one of the one or more TCI states.

[0016] In an aspect of the disclosure, the MAC-CE can include: a first field; and a second field to indicate whether information in the first field is for the serving cell or for the candidate cell.

[0017] In an aspect of the disclosure, the MAC-CE can include: a first value; and a second value to indicate that the first value identifies the candidate cell.

[0018] In an aspect of the disclosure, the MAC-CE can include a candidate cell specific TCI state list including the one or more TCI states.

[0019] In an aspect of the disclosure, the cell switch command can further include a reference to at least one of the one or more TCI states.

[0020] In an aspect of the disclosure, receiving the cell switch command can include receiving a downlink control information (DCI) including: the candidate cell and an indication of a TCI codepoint referencing at least one of the one or more TCI states.

[0021] In an aspect of the disclosure, receiving the cell switch command can include receiving a downlink control information (DCI) including an indication of a candidate cell activated TCI state list including: the candidate cell and a TCI codepoint referencing at least one of the one or more TCI states.

[0022] In an aspect of the disclosure, receiving the cell switch command can include receiving a downlink control information (DCI) including: a reference to at least one of the one or more TCI states and an indication that the at least one of the one or more TCI states is for the candidate cell.

[0023] In one aspect of the disclosure, the method can further include that the one or more TCI states are associated with more than one physical cell identifier (PCI), and the intra-cell beam management in the target cell is performed based on the one or more TCI states.

[0024] In one aspect of the disclosure, the one or more TCI states are associated with more than one physical cell identifier (PCI), and the method can further include that at least one of intra-cell management or inter-cell management in the target cell is performed based on the one or more TCI states.

[0025] In one aspect of the disclosure, the method can further include that a list of TCI states activated by the serving cell is preserved while operating in the target cell.

[0026] In one aspect of the disclosure, the method can further include that an indication of a user equipment capability is transmitted, wherein at least one of a number of one or more TCI states activated in a MAC-CE for a candidate cell or a number of TCI states activated across multiple cells at the user equipment device is based on the UE capability.

[0027] According to an aspect of the disclosure, a network device includes at least one processor; and at least one memory. The at least one memory stores instructions that, when executed by the at least one processor, cause the network device at least to: transmit, to a user equipment device, a medium access control control element (MAC-CE) including an indication of a candidate cell and one or more transmission configuration indicator (TCI) states activated for the candidate cell; transmit, to the user equipment device via lower layer signaling, a cell handover command indicating the candidate cell as a target cell; and perform a handover of the user equipment device to the target cell in response to the cell handover command.

[0028] According to an aspect of the disclosure, a method performed by a network device. The method includes: transmitting, to a user equipment device, a medium access control control element (MAC-CE) including an indication of a candidate cell and one or more transmission configuration indicator (TCI) states activated for the candidate cell; transmitting, to the user equipment device via lower layer signaling, a cell handover command indicating the candidate cell as a target cell; and performing a handover of the user equipment device to the target cell in response to the cell handover command.

[0029] According to some aspects, the subject matter of the independent claims is provided. Some additional aspects are defined in the dependent claims. BRIEF DESCRIPTION OF DRAWINGS

[0030] Some example embodiments will now be described with reference to the accompanying drawings.

[0031] Figure 1 FIG. is a diagram of an example embodiment of a wireless network between a network apparatus and a user equipment apparatus (UE) in accordance with one illustrated aspect of the present disclosure;

[0032] Figure 2 FIG. is a diagram of a UE sweeping receive beams for a synchronization signal block (SSB) burst in accordance with one illustrated aspect of the present disclosure;

[0033] Figure 3 FIG. is a diagram of an example embodiment of a UE communicating with a master node (MN) and a secondary node (SN) in accordance with one illustrated aspect of the present disclosure;

[0034] Figure 4 FIG. is a diagram of an example embodiment of a layer 1 / layer 2 triggered mobility (LTM) scenario in accordance with one illustrated aspect of the present disclosure;

[0035] Figure 5 FIG. is a diagram of an example embodiment of operations for LTM in accordance with one illustrated aspect of the present disclosure;

[0036] Figure 6 FIG. is a diagram of an example configuration for configuring LTM in accordance with one illustrated aspect of the present disclosure;

[0037] Figure 7 FIG. is a diagram of an example transmission configuration indicator (TCI) state activation medium access control control element (MAC-CE) for a candidate cell to support LTM in accordance with one illustrated aspect of the present disclosure;

[0038] Figure 8 FIG. is a flow diagram of an example operation of a UE for LTM in accordance with one illustrated aspect of the present disclosure;

[0039] Figure 9 FIG. is a flow diagram of an example operation of a network apparatus for LTM in accordance with one illustrated aspect of the present disclosure; and

[0040] Figure 10 FIG. illustrates an example embodiment of components of a UE or network apparatus in accordance with one illustrated aspect of the present disclosure. DETAILED DESCRIPTION

[0041] In the following description, specific details are set forth to provide a thorough understanding of the disclosed aspects. However, one skilled in the relevant art will recognize that the aspects can be practiced without one or more of the specific details, or with other methods, components, materials, etc. In other instances, well-known structures associated with a transmitter, receiver, or transceiver are not shown or described in detail to avoid obscuring the description of these aspects.

[0042] In this specification, reference to “one aspect” or “an aspect” means that a particular feature, structure, or characteristic described in connection with the aspect is included in at least one aspect. Thus, the appearance of the phrase “in one aspect” or “in an aspect” in various places in the specification are not necessarily all referring to the same aspect. Furthermore, the particular features, structures, or characteristics can be combined in any suitable manner in one or more aspects.

[0043] Embodiments described in this disclosure can be implemented in wireless network devices, such as but not limited to devices utilizing Worldwide Interoperability for Microwave Access (WiMAX), Global System for Mobile Communications (GSM, 2G), GSM EDGE Radio Access Network (GERAN), General Packet Radio Service (GRPS), Universal Mobile Telecommunication System (UMTS, 3G) based on Basic Wideband Code Division Multiple Access (W-CDMA), High Speed Packet Access (HSPA), Long Term Evolution (LTE), LTE-Advanced (LTE-A), Enhanced LTE (eLTE), 5G New Radio (5G NR), Advanced 5G, 6G (and beyond), 802.11ax (Wi-Fi 6), and other wireless network systems. The term “eLTE” herein denotes LTE evolution connected to a 5G core. LTE is also referred to as Evolved UMTS Terrestrial Radio Access (EUTRA), or Evolved UMTS Terrestrial Radio Access Network (EUTRAN).

[0044] Wireless network technology has benefited in recent years from beamforming. Beamforming is a technique that can be used to direct an antenna array to transmit or receive radio signals in a particular spatial direction. Beamforming can include adjusting the phase of signals transmitted by or received from antenna elements so that the transmitted or received signals can provide constructive interference in a desired spatial direction, while destructive interference in other spatial directions. For example, in a wireless network, a base station and a user equipment device (UE) each can be equipped with one or more antenna panels or antenna arrays having antenna elements that can be configured to focus transmitted signal energy and / or received signal energy in a certain spatial direction and / or within a certain spatial angular sector or width. The base station can transmit various reference signals in various different beam directions to facilitate the UE accessing the network and communicating with the network. The base station can configure the UE to perform signal measurements (e.g., layer 1 reference signal receive power (L1-RSRP)) and report these signal measurements so that the base station and the UE can select a beam direction with the strongest signal strength to communicate. In an example, the base station can transmit a synchronization signal block (SSB) in a burst. The base station can transmit the SSB burst in various beam directions, e.g., by sweeping through a set of beam directions. To facilitate intra- and inter- frequency beam management, the base station can provide the UE with information such as a physical cell identity (PCI) or a logical ID, time domain information (e.g., SSB measurement configuration (SMTC) or periodicity and SSB time location in a burst), etc. To facilitate inter- frequency beam management, the base station can provide the UE with frequency domain information such as a center frequency of the SSB and / or a subcarrier spacing (SCS) of the SSB. In general, the base station can transmit any suitable reference signal (e.g., a predetermined waveform or a predetermined sequence) and provide the UE with any suitable parameters and / or configurations to facilitate signal measurements, measurement reporting, beam indication, and selection.

[0045] In an example of Fifth Generation New Radio (5GNR) defined by the Third Generation Partnership Project (3GPP), a unified TCI framework is used for beam configuration and / or indication. For example, a base station can configure a set of TCI states for a UE. Each TCI state can indicate at least a certain beam direction or a set of beam directions, which can correspond to a certain reference signal. In an example, a TCI state can be a downlink (DL) TCI state for DL communication from the base station to the UE. In another example, a TCI state can be an uplink (UL) TCI state for UL communication from the UE to the base station. In another example, a TCI state can be a joint TCI state for UL and DL communication between the base station and the UE. The base station can activate the UE with at least a subset of the configured TCI states. In some examples, the base station can activate one or more of the configured TCI states in the set and exclude other configured TCI states in the set. To communicate with the UE, the base station can select one of the activated TCI states and indicate the selected TCI state to the UE.

[0046] Because a UE can travel from one area to another, a handover or mobility procedure is important to support continuous communication (without any interruption or at least minimal interruption) of the UE with the network. In an example, a UE can be configured to monitor certain reference signal(s) (e.g., SSB, channel state information reference signal (CSI-RS), DL reference signal (RS)) from one or more base stations, perform signal measurements of the reference signal(s), and report these signal measurements to the network so that a handover of the UE to a neighboring base station is determined (upon detecting a drop in signal quality). The initiation of the handover can generally be from the network. In an example of 5GNR, a handover initiation or handover command can be signaled via high layer signaling (e.g., radio resource control (RRC) signaling). High layer signaling can involve the network and thus can have a high latency. However, some UEs can be highly mobile devices and / or can be located in a highly mobile wireless communication system. Thus, the UEs can benefit from a more efficient handover procedure triggered via low layer signaling (e.g., L1 / L2 signaling) that has a lower latency than high layer signaling. As used herein, a handover triggered via low layer signaling can be referred to as low layer triggered mobility (LTM). In some cases, a candidate cell for LTM can be referred to as an LTM candidate cell.

[0047] Aspects of the present disclosure provide techniques for beam indication in LTM procedures by using cell-specific TCI state or a list of cell-specific TCI states. In an aspect of the present disclosure, a serving cell (e.g., a base station, a centralized unit (CU) (e.g., a server or a host), a distributed unit (DU) (e.g., a radio head), a network node, or generally a device of the serving cell) can configure a UE with one or more candidate cells and a list of one or more TCI states for each of the candidate cells. For an individual candidate cell, the serving cell can activate one or more of the respective configured TCI states. In other words, the TCI state activation is cell-specific. The serving cell can then transmit a cell switch command to the UE via a lower layer signal (e.g., L1 / L2 signaling). In an example, the cell switch command can be transmitted upon detecting a drop in signal quality between the UE and the base station. The cell switch command can indicate one of the candidate cells as a target cell (for switching). In response to the cell switch command, the UE can switch to communicate with the target cell (e.g., a base station, a CU, a DU, a network node, or generally a device of the target cell). The UE can communicate with the target cell by applying at least one of the activated TCI state(s). In an aspect, the activation of the TCI state(s) for a candidate cell can be implemented via medium access control control element (MAC-CE) signaling.

[0048] Aspects of the present disclosure provide various advantages. For example, the (pre-)activation of the TCI state for a candidate cell enables the UE to start tracking the RS (of the candidate cell) associated with the TCI state at an earlier time (e.g., before the beam indication to apply the beam / TCI state(s) for communication is indicated to the UE) while the UE is in the serving cell. This can therefore allow and / or enable a more efficient cell switching procedure (e.g., reduce cell switching delay) compared to a case where the UE is not provided any (pre-)activated TCI state.

[0049] The present disclosure can use the term “serving cell” to refer to a base station, a CU, a DU, a network node, or a network device of a serving cell of a UE, and can use the term “target cell” to refer to a base station, a CU, a DU, a network node, or a network device of a target cell for cell switching. The serving cell can be a PCell (primary cell or SpCell, special cell) or a SCell (secondary cell)

[0050] Figure 1is a diagram of an example embodiment of a wireless network between a network apparatus 110 and a user equipment apparatus (UE) 150. The network apparatus 110 is configured to form beams 120 in multiple directions, and the UE 150 is also configured to form beams 160 in multiple directions. Those skilled in the art will appreciate that the ability to beamform in multiple directions can be implemented using an arrangement of multiple radiating elements, which can also be referred to as an “array” of radiating elements. Beamforming (also referred to as spatial filtering) enables directional signal transmission or reception by exploiting individual arrays and / or by combining elements in the array at specific angles to produce constructive or destructive interference. The following description can refer to “wide beams”. Those skilled in the art will appreciate and recognize wide beams for any given array. For example, those skilled in the art will appreciate and recognize wide beams based on half-power beamwidth. In embodiments, a wide beam can be produced by a single radiating element of an array or by multiple radiating elements with specific weights (i.e., phase shifter settings).

[0051] Examples of wireless network apparatuses that apply beamforming in multiple directions include, but are not limited to, apparatuses implementing 5G NR and apparatuses implementing Wi-Fi 6, among others. The present disclosure describes embodiments related to 5G NR (and several generations after 5G), as well as embodiments related to aspects defined by 3GPP. For such embodiments, the network apparatus 110 can be a gNodeB (also referred to as gNB). However, it is contemplated that embodiments related to other wireless network technologies are also included within the scope of the present disclosure.

[0052] In radio communications, a node can be implemented at least in part by a CU (e.g., a server or host) operably coupled to one or more DUs (e.g., radio heads). In embodiments, node operations can be distributed among multiple centralized units (e.g., servers or hosts). In embodiments, network nodes in a 5G wireless network can be implemented based on a so-called CU-DU split. In embodiments, processing tasks can be performed in the CU or the DU, and the transfer of responsibilities between the CU and the DU can be configured according to a particular implementation.

[0053] With continued reference to Figure 1 In an example of a 5G NR network, the network apparatus 110 provides a cell that defines a coverage area of the network apparatus 110. As described above, the network apparatus 110 can be a gNB of a 5G NR network, or can be any other apparatus configured to control radio communications and manage radio resources within a cell. As used herein, the term “resource” can refer to a radio resource, such as a physical resource block (PRB), a radio frame, a subframe, a time slot, a subband, a frequency region, a subcarrier, a beam, etc. In embodiments, the network apparatus 110 can be referred to as a base station.

[0054] The UE 150 can include, but is not limited to, a smartphone, a tablet computer, a portable computer, a vehicle-mounted wireless terminal device, an Internet of Things (IoT) device, and / or a watch or other wearable device, etc. The network apparatus 110 can provide wireless access to the UE 150 for other networks, such as the Internet. The wireless access can include downlink (DL) communications from the network apparatus 110 to the UE 150 and uplink (UL) communications from the UE 150 to the network apparatus 110. As used herein, the terms “transmit” and / or “receive” can refer to wireless transmission and / or reception, respectively, via a wireless propagation channel over a radio resource. There can be other UEs in the cell, and each of these other UEs can be served by the same or a different network apparatus, such as the network apparatus 110.

[0055] 3GPP defines 5G NR frequency ranges, such as Frequency Range 2 (FR2) covering frequencies from 24.25 GHz to 52.6 GHz, which includes high frequencies, and includes frequency bands with very high bandwidths that can accommodate high data rate use cases. Such frequency bands can be subject to challenging propagation conditions, such as high path loss, environmental absorption, and penetration loss, etc. To address such situations, beam management procedures can be used, such as using highly directional beams at the network apparatus 110 and the UE 150.

[0056] With continued reference to Figure 1 , various examples of beams 120 for the network apparatus 110 are illustrated, and various examples of beams 160 for the UE 150 are illustrated. A result of using highly directional beams is that some of the network apparatus beams 120 can not be usable with some of the UE beams 160 due to large directional differences. Thus, the UE 150 “sweeps” its beams 160, and the network apparatus 110 “sweeps” its beams 120, to determine which beam pair has the highest signal power and thus is best suited for use in communications. Due to various propagation conditions, beams that are not perfectly directionally aligned can have the highest signal power. Sweeping will combine Figure 2 are described in more detail. After identifying such a beam pair, the UE 150 and the network apparatus 110 can use the identified beams to initiate an access procedure for the UE 150 to access the network apparatus 110.

[0057] Figure 2 is a diagram of an example embodiment of a UE sweeping a receive beam for an SSB burst. Using Figure 1, network device 110 sequentially forms beams B1, B2, B3, and B4. Each formation of a beam is referred to as a "burst." Network device 110 may generate bursts at intervals for observation by UE 150. Each time between intervals is referred to as a "burst period," which may be longer than the duration of the burst. Those skilled in the art will appreciate that beamforming for transmission is achieved by controlling the phase and relative amplitude of the transmission signal at each radiating element in the array to produce a desired constructive and destructive interference pattern in a desired wavefront. In contrast, beamforming for reception is achieved by combining information from different elements of the array so that radiation in a target spatial region is preferentially observed.

[0058] In the example of 5G NR, each beam in a burst sends information about the beam in a so-called signal synchronization block (SSB). Network device 110 (which may be a gNodeB) sends the SSB in each beam in a burst. In some examples, network device 110 may operate using one SSB (single beam operation) or using multiple SSBs (multi-beam operation). In an embodiment, UE 150 may receive a burst of SSBs for each of its receive beams. Figure 1 In the example of four receive beams R1, R2, R3 and R4 shown in FIG, four intervals are required for receiving a burst, such as Figure 2 . In some examples, the UE 150 can operate using a single beam (e.g., an omnidirectional beam). The SSBs of an SS burst can be provided by one or more (collocated or non-collocated) TRPs (transmit receive points). The duration between bursts is called a "burst period". In 5G NR networks, SSB bursts each last 5ms and the burst period has a default duration of 20ms. Nothing in this document is limited to a specific downlink reference signal. For example, a downlink beam can be identified by a CSI-RS (channel state information reference signal) identifier and / or by an SSB (e.g., SS / PBCH block, synchronization signal physical broadcast channel) identifier and / or any reference signal / sequence sent using a beam / spatial filter.

[0059] In an example of 5G NR, each SSB includes: a master information block (MIB) form, and system information (SI) of a plurality of system information blocks (SIBs). The SI is divided into minimum SI and other SI. The minimum SI includes: basic information that can be used to access the network node, and information for acquiring any other SI. The minimum SI includes the MIB that contains cell barring status information and physical layer information of the cell for receiving additional system information (e.g., CORESET#0 configuration). The MIB is periodically broadcast on a broadcast channel (BCH). The minimum SI also includes system information block 1 (SIB1) that defines the scheduling of other system information blocks and contains information for accessing the network node. The SIB1 can also be referred to as remaining minimum SI (RMSI) and is periodically broadcast on a downlink shared channel (DL-SCH).

[0060] More specifically, in an embodiment, the MIB on the common broadcast channel (PBCH) can provide the UE 150 with parameters (e.g., CORESET#0 configuration) for monitoring a common downlink control channel (PDCCH) for scheduling of a common downlink shared channel (PDSCH) that carries the SIB1. In an embodiment, the PBCH can indicate that there is no associated SIB1, in which case the UE 150 can be pointed to another frequency in which to search for SSBs associated with SIB1, and can be pointed to a frequency range in which the UE 150 can assume that there are no SSBs associated with SIB1. The indicated frequency range can be limited to within the same operator’s contiguous spectrum allocation in which the SSB was detected.

[0061] With continued reference to Figure 2 For each transmit-receive beam pair, the UE 150 measures the reference signal received power (RSRP). In an embodiment, the beam pair with the largest RSRP is selected. In an embodiment, any beam pair with sufficient RSRP can be selected. After the beam pair is identified, the UE 150 decodes the SSB of the selected network node transmit beam, and decodes the contents thereof, such as the MIB and / or SIB1. As described above, the MIB contains information of the cell for receiving additional system information, and the SIB1 defines the scheduling of other system information blocks and contains information for accessing the network node. Such information can be used by the UE 150 to establish a connection with the network apparatus 110.

[0062] In some examples, the characteristics of each of the transmit-receive beam pairs can be mapped to a TCI state. In one example, a transmit-receive beam pair can be mapped to a DL TCI state for DL communications from the network to the UE, and a UL TCI state for UL communications from the UE to the network. In another example, a transmit-receive beam pair can be mapped to a joint TCI state for UL and DL communications between the network and the UE.

[0063] Figure 1 and Figure 2 The examples are illustrative only. In embodiments, the number and direction of network node beams and the number and direction of UE beams can vary and can be different than those shown in Figure 1 and Figure 2 .

[0064] In some examples, in addition to beamforming, it can be beneficial for the network to utilize dual connectivity and / or carrier aggregation to increase bandwidth and bit rate for communications with the UE, which will be discussed more fully below in connection with Figure 3 .

[0065] Figure 3 is a diagram of an example embodiment of a UE 310 communicating with a MN 320 and a SN 330. The UE 310 can be substantially similar to the UE 150 of Figure 1 . In embodiments, the MN 320 and / or SN 330 can be a 5G NR node (e.g., gNB) or a LTE network node (e.g., eNB) as well as other types of nodes. In embodiments, the MN 320 and / or SN 330 can be a base station. The UE 310 can operate in a dual connectivity mode. Dual connectivity allows the UE 310 to be connected to two network nodes (e.g., the MN 320 and the SN 330 as shown) at the same time.

[0066] In an embodiment, the MN 320 is connected to a core network, such as a 5G core (5GC), and provides a control plane connection between the UE 310 and the core network, while the SN 330 is connected to the MN 320 (e.g., via an Xn interface) and provides additional resources for user plane services. In an embodiment, the MN 320 processes signaling messages, such as RRC signaling messages. In an embodiment, the SN 330 may also process signaling messages, such as RRC signaling messages, using signaling radio bearers (SRBs) for LTE networks (e.g., SRB0, SRB1, and / or SRB2) and / or for 5G NR networks (e.g., SRB3). Those skilled in the art will appreciate that RRC is used by nodes and UEs for various radio resource operations, such as, but not limited to, connection management and mobility functions. As used herein, the term "resource" may refer to radio resources, such as physical resource blocks (PRBs), radio frames, subframes, time slots, subbands, frequency regions, subcarriers, beams, and the like. As used herein, the terms "transmit" and / or "receive" may refer to wireless sending and / or receiving, respectively, via a wireless propagation channel on radio resources. RRC and SRB will be understood by those skilled in the art.

[0067] like Figure 3 As further shown in the example of , carrier aggregation can be used in conjunction with dual connectivity. Carrier aggregation enables UE310 to connect to multiple cells simultaneously so as to operate on multiple frequencies simultaneously. In an embodiment, multiple cells may be located at a single base station and / or a common location (e.g., a small cell or femto cell at a facility). The one or more cells that a UE can use under carrier aggregation may be referred to as a "cell group". When carrier aggregation is used with dual connectivity, the MN and / or SN may have a cell group. The cell group of the MN may be referred to as a master cell group (MCG), and the cell group of the SN may be referred to as a secondary cell group (SCG). The MCG includes a primary cell (PCell) and may include one or more secondary cells (SCells). The SCG includes a primary cell of a secondary cell group (PSCell) and may include one or more secondary cells (SCells). In Figure 3 In the example shown, MN 320 includes one PCell 322 and one SCell 324. Similarly, SN 330 includes one PCell 332 and one SCell 334. Each of PCell 322, SCell 324, PCell 332, and SCell 334 may be connected to a network. Figure 1 The network devices 110 of FIG. 1 and 2 may be operated in a substantially similar manner. One skilled in the art will understand the characteristics and functions of such cells and cell groups.

[0068] In some examples, the MN 320 and / or the SN 330 can communicate with the UE 310 utilizing beamforming techniques, as described above with reference to Figure 1 and Figure 2 .

[0069] As described above, a UE can travel from one area to another, and thus handover or mobility procedures are important to support continuous communication of the UE with the network. Moreover, more efficient handover procedures, such as LTM, are beneficial to avoid or at least reduce any interruption of service of the UE as it moves from one cell coverage to another.

[0070] Figure 4 is a diagram of example embodiments of an LTM scenario. As shown in Figure 4 , the UE 410 can be in communication with and served by a network device 420 (e.g., a base station, gNB), as shown by the solid arrow. The UE 410 can be substantially similar to the UE 150 of Figure 1 and / or the UE 310 of Figure 3 . The network device 420 can be substantially similar to the network device 110 of Figure 1 and / or the PCell 322, SCell 324, PCell 332, and SCell 334 of Figure 3 . The network device 420 that is or is currently serving the UE 410 can be referred to as a serving cell. As the UE 410 travels towards the edge of a cell or area 402 served by (or within the coverage of) the network device 420, a handover procedure can be performed to handover the UE 410 to a neighboring cell served by another network device. In the example shown in Figure 4 , one neighboring cell is served by a network device 430, and another neighboring cell is served by a network device 440. The network device 440 can cover (or serve) a cell or area 406, while the network device 430 can cover an area 404. In some examples, the areas 402, 404, and 406 can partially overlap as shown. In other examples, the areas 402, 404, and 406 can be non-overlapping. In the context of handover, a neighboring cell can be referred to as a candidate cell. In the context of LTM, a neighboring cell can be referred to as an LTM candidate cell.

[0071] In one aspect, each of the network devices 420, 430, and 440, and the UE 410 can implement beamforming as described above with reference to Figure 1 . Moreover, each of the network devices 420, 430, and 440 can transmit RS, such as described above with reference to Figure 2The discussed SSBs to facilitate signal measurement and / or reporting by a UE, such as UE 410. Further, UE 410 can be concurrently served by multiple cells, e.g., using carrier aggregation and / or dual connectivity as described above with reference to Figure 3 the discussed carrier aggregation and / or dual connectivity.

[0072] To facilitate LTM, network apparatus 420 (or a serving cell) can configure UE 410 to perform signal measurements (e.g., L1-RSRP) in various ways. In a first example, UE 410 can be provided with a configuration for L1 measurements of RSs under ServingCellConfig for its serving cell(s). In some cases, it can be useful to reuse the inter-cell beam management (ICBM) mechanism defined in 3GPP Release 17. In a second example, UE 410 can be provided with a configuration for L1 measurements of candidate cell(s) under CellGroupConfig. In a third example, UE 410 can be separately provided with L1 measurements of RSs for serving cell(s) under ServingCellConfig and L1 measurements of RSs for candidate cell(s) under CellGroupConfig. A person of skill in the art will understand the characteristics and functionality of such ServingCellConfig and CellGroupConfig.

[0073] To further facilitate beam indication for LTM, a UE 410 can be provided with beam indications associated with candidate cell(s) prior to a cell switch, after a cell switch, or as part of a cell switch command. Thus, there is a need to design an LTM framework to incorporate beam indication.

[0074] According to one aspect of the disclosure, network apparatus 420 (a serving cell) can serve UE 410 for a particular period of time and can pre-activate UE 410 with TCI state(s) for candidate cell(s). The pre-activation can be cell-specific. In this regard, network apparatus 420 can transmit an indication of activation of one or more candidate cells (e.g., network apparatus 430 and 440) and a respective list of one or more TCI states for each of the one or more candidate cells. Upon detecting a degradation in operation or communication with UE 410, serving cell network apparatus 420 can transmit a cell switch command to UE 410 via low layer signaling (e.g., L1 / L2 signaling). The cell switch command can indicate a selected one of the one or more candidate cells as a target cell for a cell switch. In response to receiving the cell switch command, UE 410 can switch to communicating with the target cell by applying at least one of the respective one or more activated TCI states.

[0075] exist Figure 4 In the example shown in FIG, UE 410 can utilize various beams for communication. Figure 4 The drawing is cluttered with only two beams 412 and 414 being illustrated. The beams 412 and 414 may be substantially similar to those described above with reference to Figures 1-2 The beam discussed. Network device 420 (serving cell) may activate a TCI state corresponding to beam 412 at UE 410 for a candidate cell operated by network device 430. Network device 420 may also activate a TCI state corresponding to beam 414 at UE 410 for a candidate cell operated by network device 440. For LTM, network device 420 may indicate a cell operated by network device 430 as a target cell. As part of a cell handover, UE 410 may switch to communicate with network device 430 (target cell), as indicated by the dashed arrow. UE 410 may communicate with the target cell using beam 412 corresponding to the TCI state activated by the serving cell. The mechanism for LTM beam indication will be referenced below. Figures 5-7 Discuss more fully.

[0076] Figure 3 and Figure 4 The examples are only illustrative. In an embodiment, the number of PCells and SCells in the MN and / or SN, the number of candidate cells, and the number of activated TCI states (or beams) may vary and may be different from Figure 3 and Figure 4 Different as shown.

[0077] Figures 5-7 The discussions are related to each other to illustrate the mechanism for LTM beam indication using TCI status, for example, extending the unified TCI framework defined by 3GPP.

[0078] Figure 5 11 is a diagram of an example embodiment of operations for LTM. These operations are implemented between UE 510, serving cell 520, and target cell 530 for LTM. In some examples, each of UE 510, serving cell 520, and target cell 530 can implement the operations using an apparatus having components as shown in FIG. One or more of the following operations can be implemented in conjunction with the operations of the present disclosure, such as those described above with reference to FIG. Figures 1-4 Examples discussed. UE 510 may be similar to UE 150, UE 310, and / or UE 410. Serving cell 520 and target cell 530 may be similar to network devices 110, 420, and / or 430. As shown, Figure 5 involves multiple enumeration steps, but Figure 5Aspects of the operations in the

[0079] In some examples, carrier aggregation can be used between the UE 510, the serving cell 520, and the target cell 530 (if the target cell is an SCell). For example, the serving cell 520 can be a PCell similar to the PCell 322 and / or 332, and the target cell 530 can be a PCell or an SCell similar to the SCell 324 and / or 334. In other words, Figure 5 The LTM operations of the Figure 5 The inter-cell beam management operations of the

[0080] As Figure 5 As shown in 502, the serving cell 520 transmits a configuration and the UE 510 receives the configuration. For example, the configuration can be received at the LTM preparation phase. The configuration can include a configuration of one or more cells (e.g., including the serving cell and / or one or more candidate cells) and a list of one or more TCI states for each of the one or more cells. The configuration can be in a variety of formats, for example, as discussed below with reference to Figure 6

[0081] Figure 6 is a diagram of an example configuration 600 for configuring LTM. The configuration 600 can be referred to as a CellGroupConfig. In general, the configuration 600 can refer to a set of cells (which can include one or more serving cells and / or one or more candidate cells) that are configured for LTM operations. The configuration 600 can include a configuration for each of a plurality of cells associated with LTM. In Figure 6 ​In the example shown, configuration 600 includes a configuration 610 for a PCell identified by index 0 and LTM index 0, which may be referred to as ServingCellConfig. Configuration 600 also includes a configuration 620 for a candidate cell identified by LTM index 1, which may be referred to as ServingCellConfig. Configuration 600 also includes a configuration 630 for a candidate cell identified by LTM index 2, which may be referred to as ServingCellConfig. Depending on which cell is serving the UE (and thus providing the configuration), the cell may have other index values, for example, an LTM cell (with index 2) may be the PCell of another UE. The LTM index referred to herein is an example, and an LTM cell may be referred to by a cell identifier, an LTM configuration index, or any identifier that may be used to refer to a particular cell. A serving cell (e.g., a PCell) may also be an LTM cell (and may be referred to by an LTM index, etc.).

[0082] Each of the configurations 610, 620, and 630 may include a TCI configuration for the corresponding cell. Figure 6 As further shown, configuration 610 includes a TCI configuration 614, which includes a TCI state list 612 for a PCell (e.g., serving cell 520) currently serving a UE (e.g., UE 510). Configuration 620 includes a TCI configuration 624, which includes a TCI state list 622 for an LTM candidate identified by LTM index 1. Similarly, configuration 630 includes a TCI configuration 634, which includes a TCI state list 632 for an LTM candidate identified by LTM index 2. Each of TCI state lists 612, 622, and 632 can include one or more TCI states (e.g., 1, 2, 3, 4, 5, 6, or more). In one aspect, each cell (e.g., serving cell, candidate cell) can have an independent configuration of TCI states or TCI state lists. Thus, for one cell, a TCI state with a particular value (e.g., 1) may refer to cell-specific (or different) transmission and / or reception characteristics, while for another cell, it may refer to a TCI with the same value. In other words, the TCI state ID# for cell 1 may include different information than the TCI state ID# for cell 2. In general, a TCI state may include any suitable parameters related to a beam or transmission.

[0083] In one aspect, for example, the UE 510 can be provided with configuration of the list(s) of TCI states (or TCI state pool) associated with each candidate cell at the LTM preparation phase. In one example, the list of TCI states can be provided / updated using RRC. In one example, such configuration can be part of the reference RRC configuration that the UE 510 can retain and / or maintain across multiple cell switches. As shown in Figure 6 In one example, the configuration of the list of TCI states corresponding to each configured LTM candidate cell can be provided under the cell group configuration (CellGroupConfig) or as part of other RRC configuration, and each LTM cell can be referenced using the LTM candidate cell identifier within the serving cell. In one example, each list of TCI states can be referenced using the LTM candidate cell identifier (or LTM index, or LTM configuration ID) within the serving cell. In another example, the configuration of the list(s) of TCI states corresponding to each configured LTM candidate cell can be provided outside of any cell group configuration. In another example, the configuration of the list(s) of TCI states corresponding to each configured LTM candidate cell can be provided using RRC signaling. For example, an LTM-specific configuration message can be used to provide the LTM candidate cell TCI state configuration.

[0084] Figure 6 The examples are merely illustrative. In embodiments, the number of LTM candidate cells and / or LTM indices indicated in the configuration can vary and can be different from what is shown in Figure 6

[0085] Returning to Figure 5 At 504, the serving cell 520 transmits and the UE 510 receives a MAC-CE (candidate cell / LTM cell TCI state activation MAC-CE or generally a message) including: a candidate cell (e.g., as referenced above with respect to Figure 4 ​The serving cell 520 can transmit a MAC-CE to indicate one or more activated TCI states for a candidate cell. The MAC-CE can include a candidate cell ID to indicate the candidate cell. The one or more activated TCI states for the candidate cell can be referred to as an activated TCI state list (candidate cell specific activated TCI list). The one or more activated TCI states can include at least a subset of the one or more configured TCI states configured for the candidate cell. In some cases, the serving cell 520 can exclude at least one of the one or more configured TCI states for the candidate cell. That is, at least one configured TCI state for the candidate cell can remain deactivated. In other cases, the serving cell 520 can activate all of the one or more configured TCI states for the candidate cell. The MAC-CE for TCI state activation can be in a variety of formats, for example, as discussed below with reference to Figure 7

[0086] Figure 7 is a diagram of an example TCI state activation MAC-CE 700 for a candidate cell to support LTM. As discussed above, the MAC-CE 700 can include a candidate cell ID to indicate the candidate cell. The MAC-CE 700 can also include an activated TCI state list to indicate one or more activated TCI states for the candidate cell. The activated TCI state list can include at least a subset of the one or more configured TCI states configured for the candidate cell. In some cases, the MAC-CE 700 can exclude at least one of the one or more configured TCI states for the candidate cell. That is, at least one configured TCI state for the candidate cell can remain deactivated. In other cases, the MAC-CE 700 can activate all of the one or more configured TCI states for the candidate cell. Figure 7 ​As shown in FIG, MAC-CE 700 includes a serving cell identifier (ID) / LTM ID (e.g., an LTM index, an LTM configuration ID, or any ID that identifies a candidate / LTM cell) field 702, an S / L field 704, and a TCI state list field 710. Serving cell ID / LTM ID field 702 may have a length of 5 bits and may indicate a serving cell ID for identifying a serving cell or an LTM ID for identifying a candidate cell to which MAC-CE 700 is applicable. The LTM ID may also be referred to as an LTM cell ID, an LTM candidate cell ID, or an LTM configuration ID. The S / L field 704 may have a length of 1 bit and may indicate whether serving cell ID / LTM ID field 702 includes a serving cell ID or a value of an LTM ID (of a candidate cell) to which MAC-CE 700 is applicable. For example, a bit value of 1 in the S / L field 704 may indicate that the serving cell ID / LTM ID field 702 includes a serving cell ID, and a bit value of 0 in the S / L field 704 may indicate that the serving cell ID / LTM ID field 702 includes an LTM ID, or vice versa. The TCI state list field 710 may have a variable length and may include a list of one or more TCI states to be activated for the cell identified by the serving cell ID / LTM ID field 702 to which the MAC-CE 700 applies. That is, if the serving cell ID / LTM ID field 702 indicates a serving cell ID, the TCI state list field 710 includes TCI state(s) to be activated for the serving cell identified by the serving cell ID. Alternatively, if the serving cell ID / LTM ID field 702 indicates an LTM ID, the TCI state list field 710 includes TCI state(s) or TCI state ID(s) to be activated for the candidate cell identified by the LTM ID.

[0087] like Figure 7 As further shown in FIG. 7 , the MAC-CE 700 includes a plurality of reserved fields 701 indicated by R, a DL bandwidth part (BWP) ID field 703, a UL BWPID field 705, a plurality of P fields indicated by P1 to P8, and a plurality of i field 706 (e.g., i is from 1 to 8) and a number of D / U fields 707 shown by D / U. Figure 7 The diagram is confusing, only one of the reserved fields is marked as 701, P i Only one of the fields is marked 706 , and only one of the D / U fields is marked 707 .

[0088] In an example, if the serving cell indicated in the serving cell ID / LTM ID (e.g., LTM index, LTM configuration ID, or any ID identifying the candidate / LTM cell) field 702 is configured as part of simultaneousU-TCI-UpdateList1, simultaneousU-TCI-UpdateList2, simultaneousU-TCI-UpdateList3, or simultaneousU-TCI-UpdateList4 specified in the 3GPP TS 38.331 document, then the MAC-CE 700 applies to all serving cells in the set simultaneousU-TCI-UpdateList1, simultaneousU-TCI-UpdateList2, simultaneousU-TCI-UpdateList3, or simultaneousU-TCI-UpdateList4.

[0089] The DL BWP field 703 indicates the DL BWP to which the MAC-CE 700 applies as a codepoint of the DCI bandwidth part indicator field specified in the 3GPP TS 38.212 document. The DL BWP ID field 703 is 2 bits in length.

[0090] The UL BWP field 705 indicates the UL BWP to which the MAC-CE 700 applies as a codepoint of the DCI bandwidth part indicator field specified in the 3GPP TS 38.212 document. The UL BWP ID field 705 is 2 bits in length.

[0091] The Pi field 706 indicates whether each TCI codepoint has multiple TCI states or a single TCI state. If the Pi field 706 is set to 1, it indicates that the ith TCI codepoint includes a DL TCI state and a UL TCI state. If the Pi field 706 is set to 0, it indicates that the ith TCI codepoint includes: a DL / joint TCI state, or a UL TCI state. The codepoint to which the TCI states are mapped is determined by its sequential position in all of its TCI state ID fields in the TCI state list field 710.

[0092] The D / U field 707 indicates whether the TCI state ID in the same octet is for joint / downlink or uplink TCI state. If the field is set to 1, the TCI state ID in the same octet is for uplink, and vice versa.

[0093] The TCI state IDs in the TCI state list field 710 indicate TCI states identified by TCI-StateId specified in the 3GPP TS 38.331 document. If the D / U field 707 is set to 1, the TCI state ID of 7-bit length is used, i.e., TCI-StateId specified in the 3GPP TS 38.331 document. If the D / U field 707 is set to 0, the most significant bit of the TCI state ID is considered as a reserved bit and the remaining 6 bits indicate UL-TCIState-Id specified in the 3GPP TS 38.331 document. In some examples, the maximum number of activated TCI states can be 16.

[0094] The reserved field 701 is a reserved bit and can be set to 0.

[0095] Those skilled in the art will appreciate that simultaneousU-TCI-UpdateListl, simultaneousU-TCI-UpdateList2, simultaneousU-TCI-UpdateList3, simultaneousU-TCI-UpdateList4, DL BWP, and UL BWP.

[0096] According to one aspect of the disclosure, the MAC-CE 700 can be part of a unified TCI framework configured to support LTM. For example, the MAC-CE 700 can be used to carry inter-cell beam indication for LTM-based cell switching and / or subsequent communications for intra- and / or inter-cell beam management in a new target cell by a UE (e.g., UEs 150, 310, 410, and / or 510), which will be discussed more fully below.

[0097] In an example, the unified TCI state activation / deactivation MAC-CE defined in the 3GPP TS 38.321 document can be as follows Figure 7the MAC-CE 700. In one aspect, the serving cell ID in the unified TCI state activation / deactivation MAC-CE can be reinterpreted to include a serving cell ID or an LTM configuration ID (e.g., to indicate an ID of an LTM candidate cell that includes the current serving cell). The unified TCI state activation / deactivation MAC-CE can include a bit field (e.g., S / L field 704) that can be relied upon for interpretation. For example, a bit field in the MAC-CE indicates whether the TCI state activation is for a serving cell (serving cell ID, S) or for an LTM candidate cell (LTM configuration index, ‘L’). If the bit field indicates S, then the activation is for the serving cell ID and serving cell beam management (e.g., intra-cell / inter-cell beam management). Alternatively, if the bit field indicates L, then the active TCI state in the MAC-CE is for the LTM candidate cell (e.g., including the current serving cell) indicated by the field.

[0098] Figure 7 The examples of FIGS. 7A-7B are merely illustrative. In general, a MAC-CE can be used to provide activation for one or more LTM candidate cells or candidate cell IDs.

[0099] As described above, the candidate cell TCI state activation MAC-CE can be in a variety of formats. In one aspect, a first field in the MAC-CE (e.g., serving cell ID / LTM ID field 702) is the identity or candidate cell configuration of a candidate cell that is conditionally present or conditionally interpreted when the MAC-CE is received. For example, the first field in the MAC-CE is interpreted in a manner that is based on the value of a bit field (e.g., S / L field 704) in the MAC-CE. For example, one value (e.g., a first value) of the bit field can indicate that the UE is to interpret the information in the first field of the MAC-CE as a serving cell ID, while another value (e.g., a second value) of the bit field can indicate that the UE is to interpret the information in the first field of the MAC-CE as an LTM candidate cell configuration ID or additional PCI value(s) or any other identity for indicating an LTM candidate cell. For example, the first value can be 1 and the second value can be 0, or vice versa. In another example, a value (e.g., 1) of the bit field in the MAC-CE can indicate that the UE is to read the first field in the MAC-CE as an LTM candidate cell configuration ID or additional PCI value or any other identity for indicating an LTM candidate cell. That is, the MAC-CE can utilize the bit field to indicate that there is information in the MAC-CE for identifying an LTM candidate cell.

[0100] Generally, the candidate cell TCI state activation MAC-CE can include a first field and a second field to indicate whether the information (e.g., cell ID or TCI state ID(s)) in the first field is for a serving cell or for a candidate cell.

[0101] Returning to Figure 5 At 506, the UE 510 and the serving cell 520 can communicate with each other. In some examples, the serving cell 520 can transmit signal measurement configuration(s) and the UE 510 can receive the signal measurement configuration(s) (e.g., L1-RSRP measurement configuration for SSB, CSI-RS, DL RS, and / or any RS). In response, the UE 510 can transmit signal measurement report(s) and the serving cell 520 can receive the signal measurement report(s), as described above. Generally, at 506, the serving cell 520 can serve the UE 510 by communicating any suitable communication signals with the UE 510.

[0102] At 508, a cell handover command is transmitted via low layer signaling (e.g., via medium access control (MAC) or physical layer signaling, L1 / L2 signaling), the serving cell 520 transmits and the UE 510 receives the cell handover command indicating a candidate cell (one or more TCI states for which were activated at 504) as a target cell (illustrated by the target cell 530). For example, at 504, the cell handover command can include an indication of a target cell ID corresponding to the candidate cell ID in a MAC-CE. The serving cell 520 can select the candidate cell using any suitable mechanism, e.g., based on best signal quality of the candidate cells in the candidate cell set.

[0103] At 509, in response to the cell handover command, the serving cell 520 can perform a handover of the UE 510 to the target cell 530. The handover can include forwarding information associated with the UE 510 and / or any pending data to the target cell.

[0104] At 512, in response to the cell handover command, the UE 510 switches communications to the target cell 530. The UE 510 communicates with the target cell 530 by applying at least one of the one or more TCI states activated at 504.

[0105] In one aspect, the TCI state activation for the candidate cell at 504 can include a single (only one) activated TCI state, and the cell switch command at 508 can exclude any TCI state indication or can indicate that no TCI state is provided. In this aspect, when the UE 510 receives the cell switch command without any TCI state or with an indication that no TCI state is provided, the UE 510 considers the cell switch command to implicitly indicate the single activated TCI state. Thus, the UE 510 can apply the single activated TCI state at 512 to communicate with the target cell 530. In another aspect, if the TCI state activation for the candidate cell at 504 includes a single (only one) TCI state, and the cell switch command at 508 includes an indication of a TCI state, the UE 510 can consider the TCI state to be indicated (for the cell switch) when the TCI state in the cell switch command is the same (or matches) the activated TCI state ID.

[0106] In one aspect, upon receiving the MAC-CE, the UE 510 can consider (e.g., at 504) the activated TCI state for the LTM cell received in the MAC-CE to be valid. In one aspect, when the UE 510 subsequently receives another MAC-CE for an activated (or updated) TCI state for the same LTM cell, the earlier activated TCI state can be updated by the TCI state activated by the latest MAC-CE.

[0107] In one aspect, the UE 510 can be configured to receive one or more MAC-CEs providing TCI state activation. The configuration can be based on UE capability. For example, the UE capability can indicate how many MAC-CEs associated with different LTM candidate cells can be provided to the UE 510 and / or how many cells can be associated with the activated TCI state list described herein. In one example, there can be a maximum (or threshold) number N of activated TCI states across different LTM candidate cells supported by the UE 510. In one example, the value N can include the active TCI states for cell beam management at the current serving cell. In other words, the value N can be the total number of active TCI states supported by the UE 510 for the current serving cell and any other LTM candidate cell. In another example, the value N can exclude the active TCI states for cell beam management at the current serving cell. In other words, N can be the total number of active TCI states supported by the UE 510 for the LTM candidate cells.

[0108] In one aspect, when (multiple) MAC-CE based TCI state activation is provided for the LTM, the DCI based beam indication can be used to indicate a cell switch command (e.g., at 508) as described herein. In a first example, the DCI based beam indication can include an LTM index, an LTM configuration ID, etc. (e.g., an additional PCI index, which is a logical index to a list of PCIs configured as LTM candidates), and a TCI codepoint mapping to the TCI indication. Referring to the example TCI state activation MAC-CE 700 shown in Figure 7 In a first example, the DCI based beam indication can include an LTM index, an LTM configuration ID, etc. (e.g., an additional PCI index, which is a logical index to a list of PCIs configured as LTM candidates), and a TCI codepoint mapping to the TCI indication. Referring to the example TCI state activation MAC-CE 700 shown in

[0109] In general, the cell switch command can be carried in a DCI or a MAC-CE. The DCI or the MAC-CE can include: a candidate cell (as a target cell for the cell switch), and an indication of a TCI codepoint. The TCI codepoint can refer to at least one TCI state in a list of one or more TCI states activated for the candidate cell, where the activation can be based on a signaled candidate LTM configuration ID (etc.) in the candidate cell TCI state activation MAC-CE.

[0110] In one aspect, after receiving and applying the cell switch command, the UE 510 can determine to use the active TCI state list (activated at 504) for the new serving cell (e.g., target cell 530) to which the cell switch command is applied. For example, when the UE 510 enters the new target cell (e.g., target cell 530), the UE 510 considers the “active TCI state list” to be valid for intra-cell beam management. In other words, the list is the active TCI state list of the current serving cell (e.g., PCell) for which the UE 510 performs the switch. The active TCI states in the active TCI state list can reference TCI states provided in the RRC configuration. For example, the UE retains the active TCI state list activated after the cell switch and the TCI state list from which the TCI states are activated (RRC configuration). In another example, if the active TCI state list of the serving cell 520 (activated at 506) is associated with more than one PCI, when the UE 510 enters the new target cell, the UE 510 considers the “active TCI state list” to be valid for inter-cell beam management and intra-cell beam management. Beam management can generally refer to procedures and / or mechanisms related to forming, controlling, and / or detecting beams. Beam management can include various stages, for example, during initial access by a UE or while the UE is in connected mode. In inter-cell beam management, the UE can be configured to communicate with a cell having a different PCI than the serving cell while maintaining a connection with the serving cell.

[0111] In one aspect, when the UE 510 applies the MAC-CE that is used to activate the TCI states for the LTM cell (e.g., at 504), the active TCI states are considered to be valid before the cell switch command is applied at 508. For the cell for which the cell switch is triggered / signaled (e.g., target cell 530), the list (of active TCI states) becomes the intra-cell (or inter-cell) beam management list. For other cells, the TCI states are not considered to be active (i.e., they are deactivated).

[0112] In one aspect, the UE 510 can retain the list of activated TCI states activated by the source cell (previous serving cell 520) while operating in the target cell 530. The list of activated TCI states can be for the previous serving cell 520, any previous serving cell, or other candidate cells. For example, the UE 510 can store the list of activated TCI states in a memory (e.g., memory 1150) of the UE 510 after receiving the list of activated TCI states, and can not overwrite or delete the stored list of activated TCI states. In one aspect, whether to maintain and / or retain the active TCI states at the UE 510 after a cell handover can be configured. The configuration can be cell-specific. For example, the UE can receive a configuration (e.g., from the serving cell 520) or indication that can indicate whether to deactivate or maintain the list of active TCI states (for the target cell, and / or other candidate cells for which the TCI states have been activated) after the UE 510 enters the target cell 530. In one aspect, the UE 510 can receive the configuration or indication as part of a cell handover command (e.g., in a DCI) or RRC configuration (e.g., RRC pre-configuration).

[0113] In another aspect, the current serving cell ID (which can also be identified by an LTM configuration index or LTM index) can be referenced with the MAC-CE activating the TCI states for intra-cell beam management. In an example, if the current serving cell 520 is referenced (e.g., referred to as a candidate cell (LTM) index or with) in the MAC-CE activating the TCI state(s) using an LTM-specific index, the UE 510 determines that the TCI state(s) provided in the activating MAC-CE are activated after the UE 510 applies a cell handover to the new target cell 530. In other words, the serving cell can be configured and activated with TCI states for LTM operation (and at the same time the serving cell can have a list of activated TCI states for intra-cell beam management).

[0114] Figure 5 The examples of FIGS. 10A and 10B are merely illustrative. In embodiments, the number of candidate cell TCI state activation MAC-CEs from the serving cell 520 to the UE 510, the number of candidate cells for which TCI states are activated in each candidate cell TCI state activation MAC-CE, and / or the number of TCI states for activation per candidate cell can vary and can be different than Figure 5The serving cell 520 can transmit one MAC-CE to activate TCI state(s) for each LTM candidate cell, in some examples. In other examples, the serving cell 520 can transmit one MAC-CE to activate TCI state(s) for multiple LTM candidate cells. In some examples, the candidate cell TCI state activation MAC-CE can include a candidate cell specific TCI state activation list for each candidate cell. In some examples, the candidate cell TCI state activation MAC-CE can include multiple candidate cell IDs and a separate TCI state activation list for each of the multiple candidate cells. In some examples, the candidate cell TCI state activation MAC-CE can be a 3GPP defined modified or extended unified TCI state activation MAC-CE. In other examples, the candidate cell TCI state activation MAC-CE can be a MAC-CE (or message in general) identified by a specific ID for TCI state activation for LTM candidate cells. Figure 8 is a flowchart of example operations of a UE (such as the UE 150, 310, 410, and / or 510) for LTM. Figure 8 The operations of can include similar mechanisms as discussed above with reference to Figures 5-7 As illustrated, Figure 8 includes multiple enumerated steps, but Figure 8 Aspects of the operations in can include additional steps before, after, and in between the enumerated steps. In some aspects, one or more of these enumerated steps can be omitted or performed in a different order.

[0115] At 802, the operations include receiving, from a serving cell, a MAC-CE including: a candidate cell and an indication of activation of one or more TCI states for the candidate cell. In examples, the serving cell can correspond to the serving cell 520. In one example, the MAC-CE can be received from a serving cell network device, such as the network device 110, the MN 320, the PCell 322 (e.g., a PCell network node), a CU, a DU, and / or the network devices 420, 430, 440.

[0116] In aspects, the MAC-CE includes: a first field and a second field to indicate whether the information in the first field is for the serving cell or for the candidate cell. For example, the second field can be similar to the TCI state activation field discussed above with reference to Figure 7the S / L field 704 in the MAC-CE 700 to provide conditional interpretation of the first field. In one aspect, the MAC-CE includes a first value and a second value to indicate that the first value identifies a candidate cell. In one aspect, the MAC-CE includes a value to indicate that one or more TCI states of the candidate cell are activated. In one aspect, the MAC-CE includes a list of candidate cell specific TCI states including an indication of a candidate cell (e.g., LTM ID) and one or more TCI states activated (for the candidate cell).

[0117] At 804, the operations include receiving a cell switch command from the serving cell via lower layer signaling, the cell switch command indicating the candidate cell as a target cell. The lower layer signaling includes at least one of L1 signaling or L2 signaling.

[0118] In one aspect, receiving the cell switch command includes receiving a DCI including an indication of the candidate cell and a TCI codepoint referencing at least one of the one or more TCI states. In one aspect, receiving the cell switch command includes receiving a DCI including an indication of a list of candidate cell activated TCI states including the candidate cell and a TCI codepoint referencing at least one of the one or more TCI states. In one aspect, receiving the cell switch command includes receiving a DCI including an indication of a reference to at least one of the one or more TCI states and an indication that the at least one of the one or more TCI states is for the candidate cell.

[0119] At 806, the operations include switching communications to the target cell in response to the cell switch command. Switching to the target cell includes communicating with the target cell by applying the at least one of the one or more TCI states. In one aspect, carrier aggregation can be used for communications with the UE as described above with reference to Figure 3 the target cell (if the target cell is an SCell). In such an aspect, the serving cell can be a PCell and the candidate cell can be a candidate PCell. Thus, switching communications to the target cell can refer to switching communications from the serving PCell to the target PCell. In another aspect, the serving cell can be a PCell and the candidate cell can be a candidate PCell. Thus, switching communications to the target cell can refer to switching communications from the serving PCell to the target SCell.

[0120] In one aspect, the cell switch command at 804 further includes a reference (e.g., TCI codepoint) to at least one of the one or more TCI states (activated at 802). In another example, whether the cell switch command provides beam indication / TCI state indication in the form of TCI codepoint or TCI state ID can be configurable. In one example, the cell switch command can indicate whether at least one TCI state is indicated using TCI codepoint or TCI state ID. In an example, if separate TCI states (separate TCI states for uplink and downlink) are indicated, the cell switch command can refer to TCI codepoint of TCI state (e.g., to reduce indication overhead). In an example, if separate TCI states (separate TCI states for uplink and downlink) are indicated, the cell switch command can refer to cell switch TCI state ID for downlink and uplink. The TCI states can be listed in order of DL TCI state ID and UL TCI state ID. In one example, the DCI scheduling the cell switch command can include TCI codepoint indicating the TCI state(s) for the target cell. The cell switch command providing indication (e.g., beam indication) of TCI state (in any embodiment) can refer to any MAC CE that activates the TCI state for LTM-based beam indication (and / or for further communication in the target cell).

[0121] In one aspect, the cell switch command at 804 further includes a reference to a TCI state, and applying at least one of the one or more TCI states is based on a match between the TCI state referenced in the cell switch command and at least one of the one or more TCI states. For example, if the cell switch command indicates TCI state ID 2, and the one or more activated TCI states include the same TCI state ID 2, the UE can apply TCI state ID 2 for communication with the target cell. However, if the cell switch command indicates TCI state ID 2, and the one or more activated TCI states do not include TCI state ID 2, the UE can not apply TCI state ID 2 indicated by the cell switch command. In this case, the UE can determine to trigger a random access procedure on the candidate cell. Alternatively, the UE can use TCI state ID 2 as the target / indicated TCI state ID, and determine that TCI state ID (#2) is an unknown TCI state to the UE, and further apply a longer beam application time (i.e., a time after which the UE is assumed to use / apply the new TCI state). The beam application time can include performing one or more measurements on DL RS indicated by the TCI state.

[0122] In one aspect, the UE also performs intra-cell beam management in the target cell based on the one or more TCI states. In one aspect, the one or more TCI states are associated with more than one PCI, and the UE performs intra-cell beam management and inter-cell beam management in the target cell based on the one or more TCI states. Some example operations of beam management can include forming, controlling, and / or detecting beams.

[0123] In one aspect, the UE can also retain the list of TCI states activated by the serving cell (e.g., the previous source cell) at 802 while operating in the target cell. In one aspect, retaining the list of TCI states activated by the serving cell while operating in the target cell is based on a configuration including an indication to retain the list of TCI states activated by the previous serving cell. In one aspect, the configuration is a cell-specific configuration. In one aspect, the cell handover command at 804 includes the configuration. In another aspect, the UE can also receive the configuration in an RRC configuration (e.g., a cell-specific RRC configuration).

[0124] In one aspect, the UE can also transmit an indication of a UE capability (e.g., indicating a threshold number of activated TCI states supported by the UE), where at least one of the number of one or more TCI states in a MAC-CE for a candidate cell or the number of TCI states activated across multiple cells is based on the UE capability.

[0125] In one aspect, the UE can also receive another MAC-CE from the serving cell including an indication of one or more TCI states to be activated for the serving cell after switching to the target cell. In one aspect, the UE can also receive a configuration including an indication of one or more candidate cells for low layer triggered mobility and a list of TCI states for each of the one or more candidate cells.

[0126] Figure 9 is a flowchart of example operations of a network apparatus, such as network apparatus 110, MN 320, PCell 322 (e.g., a PCell network node), a CU, a DU, network apparatus 420, 430, 440, and / or serving cell 520 (e.g., a serving cell network node). Figure 9 The operations of can include similar mechanisms as discussed above with reference to Figures 5-7 The operations of Figure 9 include a number of enumerated steps, but Figure 9 Aspects of the operations of can include additional steps before, after, and in between the enumerated steps. In some aspects, one or more of these enumerated steps can be omitted or performed in a different order.

[0127] At 902, the operations include transmitting, to a UE (e.g., UE 150, 310, 410, 510), a MAC-CE including: an indication of a candidate cell and activation of one or more TCI states for the candidate cell. In one aspect, the MAC-CE includes: a first field and a second field to indicate whether the information in the first field is for a serving cell or for a candidate cell. For example, the second field can be similar to the S / L field 704 in the MAC-CE 700 of Figure 7 FIG. 7, to provide conditional interpretation of the first field. In one aspect, the MAC-CE includes: a first value and a second value to indicate that the first value identifies a candidate cell. In one aspect, the MAC-CE includes: a value to indicate that one or more TCI states for the candidate cell are activated. In one aspect, the MAC-CE includes: a candidate cell specific TCI state list including: a candidate cell (e.g., LTMID) and an indication of activation (for the candidate cell) of one or more TCI states.

[0128] At 904, the operations include transmitting, to the UE via lower layer signaling, a cell switch command indicating the candidate cell as a target cell. In one aspect, the cell switch command also indicates a reference to at least one of the one or more TCI states activated at 902. In another aspect, the cell switch command does not include any additional TCI state indication or reference, and the network apparatus can expect the UE to utilize the one or more TCI states activated at 902 when switching to the target cell.

[0129] At 906, the operations include performing, in response to the cell switch command, a handover of the UE to the target cell. The handover can include forwarding information associated with the UE 510 and / or any pending data to the target cell.

[0130] Figure 10An example embodiment illustrating a block diagram of example components of a UE or network apparatus. For example, the UE can correspond to the UE 150, 310, 410, or 510, and the network apparatus can correspond to the network apparatus 110, MN 320, PCell 322 (e.g., a PCell network node), network apparatus 420, 430, 440, or a network apparatus of the serving cell 520 (which can be a network node, a CU, or a DU). The apparatus includes: electronic storage 1110, a processor 1120, a memory 1150, and a network interface 1140. The various components can be communicatively coupled to each other. The processor 1120 can be and can include any type of processor, such as a single core central processing unit (CPU), a multi core CPU, a microprocessor, a digital signal processor (DSP), a system on a chip (SoC), or any other type of processor. The memory 1150 can be a volatile type of memory, such as a RAM, or a non-volatile type of memory, such as a NAND flash. The memory 1150 includes computer readable instructions executable by the processor 1120 to cause the apparatus to perform various operations, including the beam indication (e.g., TCI state pre-activation and / or TCI state indication) of the LTM described herein.

[0131] The electronic storage 1110 can be and include any type of electronic storage for storing data, such as a hard drive, a solid state drive, and / or an optical disk, among other types of electronic storage. The electronic storage 1110 stores software instructions for causing the apparatus to perform its operations, and stores data associated with such operations, such as storing data related to the 5G NR standard, among other data. The network interface 1140 can implement wireless network technologies, such as 5G NR, Wi-Fi 6, and / or other wireless network technologies, and can include one or more arrays of radiating elements, such as the arrays of radiating elements described in connection with Figures 1-7 The components described are examples only, and one of skill in the art will understand that the apparatus includes other components not shown, and can include multiple any of the components shown. Such and other embodiments are considered within the scope of the present disclosure.

[0132] Figure 10 The components shown are examples only, one of skill in the art will understand that the apparatus includes other components not shown, and can include multiple any of the components shown. Such and other embodiments are considered within the scope of the present disclosure.

[0133] Further embodiments of the present disclosure include the following examples.

[0134] Example 1 includes a method performed by a user equipment device, the method comprising: receiving, from a serving cell, a medium access control control element (MAC-CE), the MAC-CE comprising: an indication of a candidate cell and an activation of one or more transmission configuration indicator (TCI) states for the candidate cell; receiving, from the serving cell via low layer signaling (e.g., via medium access control (MAC) or physical layer signaling, L1 / L2 signaling), a cell switch command, the cell switch command indicating the candidate cell as a target cell; and in response to the cell switch command, switching communications to the target cell, wherein the switching comprises: communicating with the target cell by applying at least one of the one or more TCI states.

[0135] In Example 2, the method of Example 1 can optionally include: wherein the MAC-CE comprises: a first field; and a second field to indicate whether information in the first field is for the serving cell or for the candidate cell.

[0136] In Example 3, the method of any of Examples 1-2 can optionally include: wherein the MAC-CE comprises: a first value; and a second value to indicate that the first value identifies the candidate cell.

[0137] In Example 4, the method of any of Examples 1-3 can optionally include: wherein the MAC-CE comprises: a candidate cell specific TCI state list, the candidate cell specific TCI state list comprising: the one or more TCI states.

[0138] In Example 5, the method of any of Examples 1-4 can optionally include: wherein the cell switch command further comprises: a reference to at least one of the one or more TCI states.

[0139] In Example 6, the method of any of Examples 1-5 can optionally include: wherein receiving the cell switch command comprises: receiving a downlink control information (DCI), the DCI comprising: the candidate cell and an indication of a TCI codepoint that references at least one of the one or more TCI states.

[0140] In Example 7, the method of any of Examples 1-5 can optionally include: wherein receiving the cell switch command comprises: receiving a downlink control information (DCI), the DCI comprising: an indication of a candidate cell activated TCI list, the candidate cell activated TCI list comprising: the candidate cell and a TCI codepoint that references at least one of the one or more TCI states.

[0141] In Example 8, the method of any of Examples 1-5 can optionally include wherein receiving the cell handover command comprises receiving a downlink control information (DCI), the DCI including a reference to at least one of the one or more TCI states and an indication that the at least one of the one or more TCI states is for the candidate cell.

[0142] In Example 9, the method of any of Examples 1-7 can optionally include wherein the cell handover command further includes a reference to a TCI state, wherein using the at least one of the one or more TCI states for communication with the target cell is based on a match between the TCI state referenced in the cell handover command and the at least one of the one or more TCI states.

[0143] In Example 10, the method of any of Examples 1-9 can optionally include performing intra-cell beam management in the target cell based on the one or more TCI states.

[0144] In Example 11, the method of any of Examples 1-9 can optionally include wherein the one or more TCI states are associated with more than one physical cell identifier (PCI), and wherein the method further includes performing at least one of intra-cell management or inter-cell management in the target cell based on the one or more TCI states.

[0145] In Example 12, the method of any of Examples 1-11 can optionally include retaining the list of TCI states activated by the serving cell while operating in the target cell.

[0146] In Example 13, the method of any of Examples 1-12 can optionally include wherein retaining the list of TCI states activated by the serving cell while operating in the target cell is based on a configuration including an indication to retain the list of TCI states activated by the serving cell.

[0147] In Example 14, the method of any of Examples 1-13 can optionally include wherein the configuration is a cell-specific configuration.

[0148] In Example 15, the method of any of Examples 1-14 can optionally include receiving the configuration in a radio resource control (RRC) configuration.

[0149] In Example 16, the method of any of Examples 1-14 can optionally include wherein the cell handover command includes the configuration.

[0150] In Example 17, a method according to any of Examples 1-6 can optionally include transmitting an indication of a UE capability (e.g., indicating a threshold number of activated TCI states supported by the UE), wherein at least one of the number of one or more TCI states activated in a MAC-CE for a candidate cell or the number of TCI states activated at the user equipment device across multiple cells is based on the user equipment capability.

[0151] In Example 18, a method according to any of Examples 1-17 can optionally include receiving another MAC-CE from the serving cell, the other MAC-CE including: a candidate cell ID corresponding to the serving cell and an indication of one or more TCI states to be activated for the serving cell after switching to the target cell.

[0152] In Example 19, a method according to any of Examples 1-18 can optionally include receiving a configuration, the configuration including: one or more candidate cells for low layer triggered mobility and an indication of a list of TCI states for each of the one or more candidate cells.

[0153] In Example 20, a method according to any of Examples 1-19 can optionally include wherein the serving cell is a primary cell.

[0154] Example 21 includes an apparatus comprising at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the user equipment device to perform at least a method according to any of Examples 1-20.

[0155] Example 22 includes an apparatus comprising means for performing at least a method according to any of Examples 1-20.

[0156] Example 23 includes a non-transitory computer-readable medium comprising program code, which, when executed by one or more processors, causes the one or more processors to perform at least a method according to any of Examples 1-20.

[0157] Example 24 includes a method performed by a network device of a serving cell, the method comprising: transmitting, to a user equipment device, a medium access control control element (MAC-CE), the MAC-CE including: a candidate cell and an indication of activation of one or more transmission configuration indicator (TCI) states for the candidate cell; transmitting, to the user equipment device via lower layer signaling, a cell handover command, the cell handover command indicating the candidate cell as a target cell; and in response to the cell handover command, performing a handover of the user equipment device to the target cell.

[0158] In Example 25, the method of Example 24 can optionally include wherein the MAC-CE includes: a first field; and a second field to indicate whether information in the first field is for a serving cell or for a candidate cell.

[0159] In Example 26, the method of any of Examples 24 to 25 can optionally include wherein the MAC-CE includes: a first value; and a second value to indicate that the first value identifies a candidate cell.

[0160] In Example 27, the method of any of Examples 24 to 26 can optionally include wherein the MAC-CE includes: a candidate cell specific TCI state list, the candidate cell specific TCI state list including: one or more TCI states.

[0161] In Example 28, the method of any of Examples 24 to 27 can optionally include wherein the cell switch command further includes: a reference to at least one of the one or more TCI states.

[0162] In Example 29, the method of any of Examples 24 to 28 can optionally include wherein transmitting the cell switch command includes: transmitting a downlink control information (DCI), the DCI including: an indication of a candidate cell and a TCI codepoint referencing at least one of the one or more TCI states.

[0163] In Example 30, the method of any of Examples 24 to 28 can optionally include wherein transmitting the cell switch command includes: transmitting a downlink control information (DCI), the DCI including: an indication of a candidate cell active TCI list, the candidate cell active TCI list including: a candidate cell and a TCI codepoint referencing at least one of the one or more TCI states.

[0164] In Example 31, the method of any of Examples 24 to 28 can optionally include wherein transmitting the cell switch command includes: transmitting a downlink control information (DCI), the DCI including: a reference to at least one of the one or more TCI states and an indication that the at least one of the one or more TCI states is for a candidate cell.

[0165] In Example 32, the method of any of Examples 24 to 31 can optionally include transmitting a configuration, the configuration including an indication of whether the user equipment device is to retain an active TCI state list activated after switching to a target cell.

[0166] In Example 33, the method of any of Examples 24 to 32 can optionally include wherein the configuration is an RRC configuration.

[0167] In Example 34, a method according to any of Examples 24 to 33 can optionally include wherein the configuration is a cell-specific configuration.

[0168] In Example 35, a method according to any of Examples 24 to 33 can optionally include wherein the cell handover command includes a configuration, the configuration including an indication of whether the user equipment device is to retain a list of activated TCI states that are activated after handover to the target cell.

[0169] In Example 36, a method according to any of Examples 24 to 35 can optionally include receiving, from the UE, an indication of a UE capability (e.g., an indication of a threshold number of activated TCI states supported by the UE); and configuring, based on the UE capability, a number of TCI states to be activated across one or more cells for the UE.

[0170] In Example 37, a method according to any of Examples 24 to 36 can optionally include transmitting, to the UE, another MAC-CE, the other MAC-CE including a candidate cell ID corresponding to the serving cell and an indication of one or more TCI states to be activated for the serving cell after handover to the target cell.

[0171] In Example 38, a method according to any of Examples 24 to 37 can optionally include transmitting a configuration, the configuration including one or more candidate cells for low-layer triggered mobility and an indication of a list of TCI states for each of the one or more candidate cells.

[0172] Example 39 includes an apparatus comprising at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the network apparatus at least to perform a method according to any of Examples 24 to 38.

[0173] Example 40 includes an apparatus comprising at least means for performing a method according to any of Examples 24 to 38.

[0174] Example 41 includes a non-transitory computer-readable medium comprising program code, which, when executed by one or more processors, causes the one or more processors to at least perform a method according to any of Examples 24 to 38.

[0175] The embodiments and aspects disclosed herein are examples of the present disclosure and can be embodied in various forms. For example, although certain embodiments herein are described as separate embodiments, each embodiment herein can be combined with one or more other embodiments herein. The specific structural and functional details disclosed herein should not be construed as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present disclosure in almost any appropriately detailed structure. Throughout the description, similar reference numerals can refer to similar or identical elements.

[0176] According to the present disclosure, the phrases “in one aspect,” “in aspects,” or “in some aspects” each can refer to one or more aspects of the same or different aspects. The phrase “plurality” can refer to two or more.

[0177] According to the present disclosure, the phrases “in one embodiment,” “in an embodiment,” “in various embodiments,” “in some embodiments,” or “in other embodiments” each can refer to one or more embodiments of the same or different embodiments. The phrase “A or B” means “(A), (B), or (A and B).” The phrase “at least one of A, B, or C” means “(A); (B); (C); (A and B); (A and C); (B and C); or (A, B, and C).”

[0178] Any of the methods, procedures, algorithms, or code described herein can be converted to or represented with a programming language or computer program. The terms “programming language” and “computer program” used herein each include any language used to specify computer instructions, and include (but are not limited to) the following languages and their derivatives: assembly language, Basic, batch files, BCPL, C, C++, Delphi, Fortran, Java, JavaScript, machine code, operating system command languages, Pascal, Perl, PL1, Python, scripting languages, Visual Basic, meta-languages that specify programs themselves, and all first-, second-, third-, fourth-, fifth-, or subsequent-generation computer languages. Database and other data schemas, and any other meta-languages are also included. No distinction is made between languages that are interpreted, compiled, or use both compilation and interpretation methods. No distinction is made between compiled and source code versions of programs. Thus, if a programming language can exist in more than one state (such as source, compiled, object, or linked), a reference to a program is a reference to any and all such states. A reference to a program can encompass the actual instructions and / or the intent of those instructions.

[0179] While aspects of the disclosure have been illustrated and described, it is not intended to limit or restrict the disclosure to the exact form disclosed. Rather, several modifications can be made and still fall within the scope of the disclosure as set forth in the appended claims.

Claims

1. A user equipment device, comprising: at least one processor; as well as at least one memory storing instructions that, when executed by the at least one processor, cause the user equipment device to at least: receiving a medium access control element (MAC-CE) from a serving cell, the MAC-CE including: a candidate cell and an indication of activation of one or more transmission configuration indicator (TCI) states for the candidate cell; receiving a cell handover command from the serving cell via low layer signaling, the cell handover command indicating the candidate cell as a target cell; and In response to the cell handover command, communication with the serving cell is switched to communication with the target cell, wherein the communication with the target cell includes communicating with the target cell by applying at least one TCI state of the one or more TCI states.

2. The user equipment device according to claim 1, wherein the MAC-CE comprises: First field; as well as The second field is used to indicate whether the information in the first field is for the serving cell or the candidate cell.

3. The user equipment device according to claim 1, wherein the MAC-CE comprises: First value; as well as The second value is used to indicate that the first value identifies the candidate cell.

4. The user equipment device according to claim 1, wherein the MAC-CE comprises: A candidate cell-specific TCI state list, wherein the candidate cell-specific TCI state list includes: the one or more TCI states.

5. The user equipment device according to claim 1, wherein the cell handover command further comprises: A reference to the at least one TCI state of the one or more TCI states.

6. The user equipment device of claim 1 , wherein the instructions, when executed by the at least one processor, further cause the user equipment device to receive the cell handover command by at least: Receive downlink control information (DCI), the DCI including: The candidate cell and an indication of a TCI code point referencing the at least one TCI state of the one or more TCI states.

7. The user equipment device of claim 1 , wherein the instructions, when executed by the at least one processor, further cause the user equipment device to receive the cell handover command by at least: Receive downlink control information (DCI), the DCI including: An indication of a candidate cell activation TCI list, the candidate cell activation TCI list including: the candidate cell, and a TCI code point referencing the at least one TCI state of the one or more TCI states.

8. The user equipment device of claim 1 , wherein the instructions, when executed by the at least one processor, further cause the user equipment device to receive the cell handover command by at least: Receive downlink control information (DCI), the DCI including: The reference to the at least one TCI state of the one or more TCI states, and the at least one TCI state of the one or more TCI states are an indication for the candidate cell.

9. The user equipment device of claim 1 , wherein the instructions, when executed by the at least one processor, further cause the user equipment device to at least: Based on the one or more TCI states, intra-cell beam management is performed in the target cell.

10. The user equipment device according to claim 1, wherein the one or more TCI states are associated with more than one physical cell identifier (PCI), and The instructions, when executed by the at least one processor, further cause the user equipment device to at least: Based on the one or more TCI states, at least one of intra-cell beam management or inter-cell beam management is performed in the target cell.

11. The user equipment device of claim 1 , wherein the instructions, when executed by the at least one processor, further cause the user equipment device to at least: While operating in the target cell, retaining a list of TCI states activated by the serving cell.

12. The user equipment device according to claim 1, The instructions, when executed by the at least one processor, further cause the user equipment device to at least: Sending an indication of the user equipment capabilities, Wherein at least one of the following items is based on the user equipment capability: the number of the one or more TCI states activated in the MAC-CE for the candidate cell, or the number of TCI states activated across multiple cells at the user equipment device.

13. A method performed by a user equipment device, the method comprising: receiving a medium access control element (MAC-CE) from a serving cell, the MAC-CE including: a candidate cell and an indication of activation of one or more transmission configuration indicator (TCI) states for the candidate cell; receiving a cell handover command from the serving cell via low layer signaling, the cell handover command indicating the candidate cell as a target cell; and In response to the cell handover command, communication with the serving cell is switched to communication with the target cell, wherein the communication with the target cell includes communicating with the target cell by applying at least one TCI state of the one or more TCI states.

14. The method according to claim 13, wherein the MAC-CE comprises: First field; as well as The second field is used to indicate whether the information in the first field is for the serving cell or the candidate cell.

15. The method according to claim 13, wherein the MAC-CE comprises: First value; as well as The second value is used to indicate that the first value identifies the candidate cell.

16. The method according to claim 13, wherein the MAC-CE comprises: A candidate cell-specific TCI state list, wherein the candidate cell-specific TCI state list includes: the one or more TCI states.

17. The method according to claim 13, wherein the cell handover command further comprises: A reference to the at least one TCI state of the one or more TCI states.

18. The method according to claim 13, wherein the receiving the cell handover command comprises: Downlink control information (DCI) is received, the DCI including the candidate cell and an indication of a TCI code point referencing the at least one TCI state of the one or more TCI states.

19. The method according to claim 13, wherein the receiving the cell handover command comprises: Downlink control information (DCI) is received, wherein the DCI includes: an indication of a candidate cell activation TCI state list, wherein the candidate cell activation TCI state list includes: the candidate cell and a TCI code point referencing the at least one TCI state of the one or more TCI states.

20. The method according to claim 13, wherein the receiving the cell handover command comprises: Downlink control information (DCI) is received, the DCI including a reference to the at least one of the one or more TCI states and an indication that the at least one of the one or more TCI states is for the candidate cell.

21. The method of claim 13, further comprising: The one or more TCI states are associated with more than one physical cell identifier (PCI), and intra-cell beam management is performed in the target cell based on the one or more TCI states.

22. The method according to claim 13, wherein the one or more TCI states are associated with more than one physical cell identifier (PCI), and The method further comprises: Based on the one or more TCI states, at least one of intra-cell management or inter-cell management is performed in the target cell.

23. The method of claim 13, further comprising: While operating in the target cell, retaining a list of TCI states activated by the serving cell.

24. The method of claim 13, further comprising: Send an indication of UE capabilities, Wherein at least one of the following items is based on the UE capability: the number of the one or more TCI states activated in the MAC-CE for the candidate cell, or the number of TCI states activated across multiple cells at the user equipment device.

25. A network device comprising: at least one processor; as well as at least one memory storing instructions that, when executed by the at least one processor, cause the network device to at least: sending a medium access control element (MAC-CE) to a user equipment device, the MAC-CE including: a candidate cell and an indication of activation of one or more transmission configuration indicator (TCI) states for the candidate cell; sending a cell handover command to the user equipment device via lower layer signaling, the cell handover command indicating the candidate cell as a target cell; and In response to the cell handover command, handover of the user equipment device to a target cell is performed.

26. A method performed by a network device, the method comprising: sending a medium access control element (MAC-CE) to a user equipment device, the MAC-CE including: a candidate cell and an indication of activation of one or more transmission configuration indicator (TCI) states for the candidate cell; sending a cell handover command to the user equipment device via lower layer signaling, the cell handover command indicating the candidate cell as a target cell; and In response to the cell handover command, handover of the user equipment device to a target cell is performed.

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