EP4690977A1

EP4690977A1 - Beam indication for layer 1/layer 2 triggered mobility (ltm)

Info

Publication number: EP4690977A1
Application number: EP24704143.7A
Authority: EP
Inventors: Timo Koskela; Sanjay Goyal; Keeth Saliya Jayasinghe LADDU
Original assignee: Nokia Technologies Oy
Current assignee: Nokia Technologies Oy
Priority date: 2023-04-05
Filing date: 2024-02-07
Publication date: 2026-02-11
Also published as: CN120814294A; WO2024208465A1; MX2025011822A; KR20260004356A

Abstract

Apparatus and methods for beam indication for layer 1 /layer 2 triggered mobility (LTM) are disclosed. Advantages of the apparatus/methods include a reduction in cell switch latency. In an aspect, a user equipment apparatus (UE) receives, from a serving cell, a medium access control-control element (MAC-CE) including an indication of a candidate cell and an activation of one or more transmission configuration indicator (TCI) states for the candidate cell. The UE further receives, from the serving cell via lower layer signaling, a cell switch command indicating the candidate cell as a target cell. The UE further switches, in response to the cell switch command, communication with the serving cell to communication with the target cell, where the communication with the target cell includes communicating with the target cell by applying at least one of the one or more TCI states.

Description

BEAM INDICATION FOR LAYER 1/LAYER 2 TRIGGERED MOBILITY (LTM)

FIELD

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

BACKGROUND

Wireless networking provides significant advantages for user mobility. A user’s ability to remain connected while on the move provides advantages not only for the user, but also provides greater efficiency and productivity for society as a whole. As user expectations for connection reliability, data speed, and device battery life, become more demanding, technology for wireless networking must also keep pace with such expectations. Accordingly, there is continuing interest in improving wireless networking technology.

SUMMARY

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

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

In an aspect of the present disclosure, the MAC-CE the MAC-CE may include a first value; and a second value to indicate that the first value identifies the candidate cell. In an aspect of the present disclosure, the MAC-CE may include a candidate cell-specific TCI state list including the one or more TCI states.

In an aspect of the present disclosure, the cell switch command may further include a reference to the at least one of the one or more TCI states.

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

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

In an aspect of the present disclosure, the instructions when executed by the at least one processor, may further cause the user equipment apparatus at least to receive the cell switch command by receiving downlink control information (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.

In an aspect of the present disclosure, the instructions when executed by the at least one processor, may further cause the user equipment apparatus at least to perform intra-cell beam management in the target cell based on the one or more TCI states.

In an aspect of the present disclosure, the one or more TCI states are associated with more than one physical cell identifiers (PCIs), and the instructions when executed by the at least one processor, may further cause the user equipment apparatus at least to perform at least one of intra- cell beam management or inter-cell beam management in the target cell based on the one or more TCI states.

In an aspect of the present disclosure, the instructions when executed by the at least one processor, may further cause the user equipment apparatus at least to retain, while operating in the target cell, a TCI state list activated by the serving cell.

In an aspect of the present disclosure, the instructions when executed by the at least one processor, may further cause the user equipment apparatus at least to transmit an indication of a user equipment capability, where at least one of a number of the one or more TCI states activated in the MAC-CE for the candidate cell or a number of TCI states activated across multiple cells at the user equipment apparatus is based on the user equipment capability.

In accordance with aspects of the present disclosure, a method performed by a user equipment apparatus. The method includes receiving, from a serving cell, a medium access control-control element (MAC-CE) including 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 lower layer signaling, a cell switch command indicating the candidate cell as a target cell; and switching, in response to the cell switch command, communication with the serving cell to communication with the target cell, where the communication with the target cell includes communicating with the target cell by applying at least one of the one or more TCI states.

In an aspect of the present disclosure, the MAC-CE the MAC-CE may include a first value; and a second value to indicate that the first value identifies the candidate cell.

In an aspect of the present disclosure, the MAC-CE may include a candidate cell-specific TCI state list including the one or more TCI states. In an aspect of the present disclosure, the cell switch command may further include a reference to the at least one of the one or more TCI states.

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

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

In an aspect of the present disclosure, the receiving the cell switch command may include receiving downlink control information (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.

In an aspect of the present disclosure, the method may further include the one or more TCI states are associated with more than one physical cell identifiers (PCIs), performing intra-cell beam management in the target cell based on the one or more TCI states.

In an aspect of the present disclosure, the one or more TCI states are associated with more than one physical cell identifiers (PCIs), and the method may further include performing at least one of intra-cell management or inter-cell management in the target cell based on the one or more TCI states.

In an aspect of the present disclosure, the method may further include retaining, while operating in the target cell, a TCI state list activated by the serving cell.

In an aspect of the present disclosure, the method may further include transmitting an indication of a user equipment capability, where at least one of a number of the one or more TCI states activated in the MAC-CE for the candidate cell or a number of TCI states activated across multiple cells at the user equipment apparatus is based on the UE capability.

In accordance with aspects of the present disclosure, a network apparatus includes at least one processor; and at least one memory. The at least one memory stores instructions which, when executed by the at least one processor, cause the network apparatus at least to transmit, to a user equipment apparatus, a medium access control-control element (MAC-CE) including an indication of a candidate cell and an activation of one or more transmission configuration indicator (TCI) states for the candidate cell; transmit, to the user equipment apparatus via lower layer signaling, a cell switch command indicating the candidate cell as a target cell; and perform a handover of the user equipment apparatus to target cell responsive to the cell switch command.

In accordance with aspects of the present disclosure, a method performed by a network apparatus. The method includes transmitting, to a user equipment apparatus, a medium access control-control element (MAC-CE) including an indication of a candidate cell and an activation of one or more transmission configuration indicator (TCI) states for the candidate cell; and transmitting, to the user equipment apparatus via lower layer signaling, a cell switch command indicating the candidate cell as a target cell; and performing a handover of the user equipment apparatus to target cell responsive to the cell switch command.

According to some aspects, there is provided the subject matter of the independent claims. Some further aspects are defined in the dependent claims.

BRIEF DESCRIPTION OF THE DRAWINGS

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

FIG. 1 is a diagram of an example embodiment of wireless networking between a network apparatus and a user equipment apparatus (UE), according to one illustrated aspect of the present disclosure;

FIG. 2 is a diagram of an example embodiment of a UE sweeping receive beams for synchronization signal block (SSB) bursts, according to one illustrated aspect of the disclosure; FIG. 3 is a diagram of an example embodiment of a UE in communications with a master node (MN) and a secondary node (SN), according to one illustrated aspect of the disclosure;

FIG. 4 is a diagram of an example embodiment of a layer 1 /layer 2 triggered mobility (LTM) scenario, according to one illustrated aspect of the present disclosure;

FIG. 5 is a diagram of an example embodiment of operations for LTM, according to one illustrated aspect of the present disclosure;

FIG. 6 is a diagram of an example configuration for provisioning LTM, according to one illustrated aspect of the present disclosure;

FIG. 7 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, according to one illustrated aspect of the present disclosure;

FIG. 8 is a flow diagram of example operations of a UE for LTM, according to one illustrated aspect of the present disclosure;

FIG. 9 is a flow diagram of example operations of a network apparatus for LTM, according to one illustrated aspect of the present disclosure; and

FIG. 10 illustrates an example embodiment of components of a UE or of a network apparatus, according to one illustrated aspect of the present disclosure.

DETAILED DESCRIPTION

In the following description, certain specific details are set forth in order to provide a thorough understanding of disclosed aspects. However, one skilled in the relevant art will recognize that aspects may be practiced without one or more of these specific details or with other methods, components, materials, etc. In other instances, well-known structures associated with transmitters, receivers, or transceivers have not been shown or described in detail to avoid unnecessarily obscuring descriptions of the aspects.

Reference throughout this specification 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 appearances of the phrases “in one aspect” or “in an aspect” in various places throughout this specification are not necessarily all referring to the same aspect. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more aspects.

Embodiments described in the present disclosure may be implemented in wireless networking apparatuses, such as, without limitation, apparatuses 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, enhanced LTE (eLTE), 5G New Radio (5G NR), 5G Advance, 6G (and beyond) and 802.1 lax (Wi-Fi 6), among other wireless networking systems. The term ‘eLTE’ here denotes the LTE evolution that connects to a 5G core. LTE is also known as evolved UMTS terrestrial radio access (EUTRA) or as evolved UMTS terrestrial radio access network (EUTRAN).

In recent years, wireless networking technology has benefited with beamforming. Beamforming is a technique by which an array of antennas can be steered to transmit radio signals or receive radio signals in a specific spatial direction. Beamforming may include adjusting the phases of signals transmitted by or received from the antenna elements so that the transmitted or received signals may provide constructive interference in the desired spatial direction and destructive interference in other spatial directions. For instance, in a wireless network, a base station and a user equipment apparatus (UE) may each be equipped with one or more antenna panels or antenna arrays with antenna elements that can be configured to focus transmit signal energy and/or receive signal energy in a certain spatial direction and/or within a certain spatial angular sector or width. The base station may transmit various reference signals in various different beam directions to facilitate the UE in accessing and communicating with the network. The base station may configure the UE to perform signal measurements (e.g., layer 1 -reference signal received power (Ll-RSRP)) and report those signal measurements so that the base station and the UE may select a beam direction with a strongest signal strength for communication. In an example, the base station may transmit synchronization signal blocks (SSBs) in bursts. The base station may transmit the SSB bursts in various beam directions, for example, by sweeping across a set of beam directions. To facilitate intra-frequency and inter-frequency beam management, the base station may provide the UE with information such as a physical cell identify (PCI) or a logical ID, time domain information (e.g., SSB measurement configuration (SMTC) or periodicity and SSB time position in a burst). To facilitate inter-frequency beam management, the base station may provide the UE with frequency domain information such as the center frequency of the SSBs and/or the sub-carrier spacing (SCS) of the SSBs. In general, the base station may transmit any suitable reference signals (e.g., a predetermined waveform or predetermined sequence) and provide the UE with any suitable parameters and/or configurations to facilitate signal measurements, measurement reporting, beam indication, and selection.

In an example of the 5th generation new radio (5G NR) as defined by 3rd Generation Partnership Project (3GPP), a unified TCI framework is used for beam configurations and/or indications. For instance, a base station may configure the UE with a set of TCI states. Each TCI state may indicate at least a certain beam direction or a group of beam directions, which may 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 examples, a TCI state can be an uplink (UL) TCI state for UL communication from the UE to the base station. In a further example, a TCI state can be a joint TCI state for UL and DL communications between the base station and the UE. The base station may activate the UE with at least a subset of the configured TCI states. In some examples, the base station may activate one or more of the configured TCI states in the set and exclude one or more of the other configured TCI states in the set. To communicate with the UE, the base station may select one of the activated TCI states and indicate the selected TCI state to the UE.

Because a UE may travel from one area to another area, handover or mobility procedures can be important to support continue communication (without any interruption or at least a minimal interruption) of the UE with the network. In an example, the UE may be configured to monitor certain reference signal(s) (e.g., SSBs, channel state information-reference signals (CSI-RSs), DL reference signals (RSs)) from one or more base stations, perform signal measurements of the reference signal(s), and report those signal measurements to the network so that a determination of a handover of the UE to a neighboring base station can be made (upon a degradation in signal quality is detected). The initiation of a handover may typically be made from the network. In an example of 5GNR, a handover initiation or handover command may be signaled via higher layer signaling, e.g., radio resource control (RRC) signaling. The higher layer signaling may involve the network, and thus can have a high latency. However, some UEs may be highly mobile devices and/or may be located in a highly mobile wireless communications system. As such, a UE may benefit from a more efficient handover procedure triggered via lower layer signaling, e.g., L1/L2 signaling, that has a lower latency than the higher layer signaling. As used herein, a handover triggered via lower layer signaling may be referred to as lower layer triggered mobility (LTM). In some instances, a candidate cell for LTM may be referred to as an LTM candidate cell.

Aspects of the present disclosure provides techniques for beam indications in LTM procedures by using cell-specific TCI states or cell-specific TCI state lists. In an aspect of the present disclosure, a serving cell (e.g., a base station, a centralized unit (CU) (e.g., server or host), a distributed unit (DU) (e.g., radio head), a network node, or generally an apparatus of the serving cell) may 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 may activate one or more of the respective configured TCI states. In other words, the TCI state activation is cell specific. The serving cell may subsequently transmit a cell switch command via lower layer signal (e.g., L1/L2 signaling) to the UE. In an example, the cell switch command may be transmitted upon detection of a degradation in signal quality between the UE and the base station. The cell switch command may indicate one of the candidate cells as a target cell (for handover). In response to the cell switch command, the UE may switch to communicate with the target cell (e.g., a base station, a CU, a DU, a network node, or generally an apparatus of the target cell). The UE may communicate with the target cell by applying at least one of the one or more activated TCI states. In an aspect, the activation of TCI state(s) for a candidate cell may be via medium access control-control element (MACE-CE) signaling.

Aspects of the present disclosure provide various advantages. For example, the (pre)activation of a TCI state for a candidate cell while the UE is in a serving cell enables the UE to start to track RSs (of the candidate cell) associated with the TCI state at an earlier time (e.g., prior to the beam indication which indicates to the UE to apply the beam/TCI state(s) for communication). As such, this may allow and/or enable a more efficient cell switch process (e.g., a reduction in cell switch latency) compared to the case when the UE is not provided with any (pre-)activated TCI states. The present disclosure may use the term “serving cell” to refer to a base station, a CU, a DU, a network node, or a network apparatus of a serving cell of a UE and may use the term “target cell” to refer to a base station, a CU, a DU, a network node, or a network apparatus of a target cell for a cell switch. Serving cell may be a PCell (primary cell or SpCell, Special cell) or an SCell (secondary cell)

FIG. 1 is a diagram of an example embodiment of wireless networking 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. As persons skilled in the art will understand, the capability to beamform in multiple directions may be implemented using arrangements of multiple radiating elements, which may also be referred as “arrays” of radiating elements. Beamforming (also known as spatial filtering) achieves directional signal transmission or reception by utilizing separate arrays and/or by combining elements in an array in such a way that signals at particular angles, which may result in constructive or destructive interference. The description below may refer to a “broad beam.” Persons skilled in the art will understand and recognize a broad beam for any given array. For example, persons skilled in the art will understand and recognize a broad beam based on half power beam width. In embodiments, a broad beam may be produced by a single radiating element of an array or by multiple radiating elements with specific weights (i.e., phase shifter settings).

Examples of wireless networking apparatuses that apply beamforming in multiple directions include, without limitation, apparatuses implementing 5G NR and apparatuses implementing WiFi 6, among others. The present disclosure describes embodiments related to 5G NR (and generations beyond 5G) and embodiments which involve aspects defined by 3GPP. With respect to such embodiments, the network apparatus 110 may be a gNodeB (also known as gNB). However, it is contemplated that embodiments relating to other wireless networking technologies are encompassed within the scope of the present disclosure.

In radio communications, a node may be implemented, at least partly, by a CU (e.g., server or host) that is operationally coupled to one or more DUs (e.g., a radio head). In embodiments, it is possible that node operations may be distributed among multiple centralized units (e.g., servers or hosts). In embodiments, a network node in 5G wireless networking may be implemented based on a so-called CU-DU split. In embodiments, a processing task may be performed in either the CU or the DU, and the shifting of responsibility between the CU and the DU may be configurable according to a particular implementation.

With continuing reference to FIG. 1, in the example of a 5G NR network, the network apparatus 110 provides a cell, which defines a coverage area of the network apparatus 110. As described above, the network apparatus 110 may be a gNB of the 5G NR network or may be any other apparatus configured to control radio communication and manage radio resources within a cell. As used herein, the term “resource” may refer to radio resources, such as a physical resource block (PRB), a radio frame, a subframe, a time slot, a sub-band, a frequency region, a sub-carrier, a beam, etc. In embodiments, the network apparatus 110 may be called a base station.

The UE 150 may include, but is not limited to, a smartphone, a tablet, portable computers, vehiclemounted wireless terminal devices, an Internet of Things (loT) device, and/or a watch or other wearable device, among others. The network apparatus 110 may provide the UE 150 with wireless access to other networks, such as the Internet. The wireless access may include downlink (DL) communication from the network apparatus 110 to the UE 150 and uplink (UL) communication from the UE 150 to the network apparatus 110. As used herein, the term “transmission” and/or “reception” may refer to, respectively, wirelessly transmitting and/or receiving via a wireless propagation channel on radio resources. There may be other UE in the cell, and each of them may be serviced by the same or by different network apparatuses, such as network apparatus 110.

3GPP defines 5G NR frequency ranges, such as Frequency Range 2 (FR2) covering 24.25 GHz to 52.6 GHz, which include high frequencies and include bands having very high bandwidths that can accommodate high data rate use cases. Such bands may be subject to challenging propagating conditions, such as high path loss, absorption from the environment, and penetration losses, among other conditions. To address such conditions, beam management procedures may be used, such as using highly directive beams at the network apparatus 110 and at the UE 150.

With continuing reference to FIG. 1, various examples of beams 120 are illustrated for the network apparatus 110 and various examples of beams 160 are illustrated for the UE 150. A consequence of using highly directive beams is that some of the network apparatus beams 120 may 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 beampairing has the highest signal power and, therefore, is best usable for communications. It is possible for beams that are not fully directionally-aligned to have the highest signal power due to various propagating conditions. The sweeps will be described in more detail in connection with FIG. 2. After identifying such a beam pairing, the UE 150 and the network apparatus 110 may use the identified beams to initiate access procedures for the UE 150 to access the network apparatus 110.

FIG. 2 is a diagram of an example embodiment of a UE sweeping receive beams for SSB bursts. Using the example beams illustrated in FIG. 1, the network apparatus 110 form beams Bl, B2, B3, and B4, successively. Each formation of the beams is referred to as a “burst.” The network apparatus 110 may generate the bursts at intervals for the UE 150 to observe. Each time between intervals is referred to as “burst period,” which may be longer than the duration of a burst. As persons skilled in the art will understand, beamforming for a transmission is implemented by controlling the phase and relative amplitude of the transmission signal at each radiating element in an array, in order to create a desired pattern of constructive and destructive interference in a desired wavefront. Beamforming for a reception, in contrast, is implemented by combining information from different elements of an array in such a way that radiation in a target spatial region is preferentially observed.

In the example of 5G NR, each beam in a burst transmits information about the beam in what is referred to as a Signal Synchronization Block (SSB). A network apparatus 110, which may be a gNodeB, transmits an SSB in each beam in a burst. In some examples, the network apparatus 110 may operate using one SSB (single beam operation) or using multiple SSBs (multi beam operation). In embodiments, the UE 150 may receive an SSB burst for each of its receive beams. In the example of four receive beams Rl, R2, R3, and R4, shown in FIG. 1, receiving the bursts takes four intervals, as shown in FIG. 2. In some examples, the UE 150 may operate using a single beam (e.g., omnidirectional beam). The SSBs of an SS burst can be provided by one or more (co- or non co-located) TRP(s) (transmit-receive points). The duration between bursts is referred to as “burst periodicity.” In a 5G NR network, SSB bursts can each last 5ms, and burst periodicity can have a default duration of 20ms. Any of the aspects herein are not limited to a particular downlink reference signal. As an example, a downlink beam may be identified by CSI-RS (channel state information reference signal) identifier and/or by SSB (e.g., SS/PBCH block, synchronization signal physical broadcast channel) identifier and/or any reference signal/sequence transmitted using the beam/spatial filter.

In the example of 5G NR, each SSB includes System Information (SI) in the form of Master Information Blocks (MIB) and a number of System Information Blocks (SIB). The SI is divided into Minimum SI and Other SI. Minimum SI includes basic information usable for accessing the network node and information for acquiring any other SI. Minimum SI includes the MIB, which contains cell-barred status information and physical layer information of the cell for receiving further system information (e.g., CORESET#0 configuration). MIB is periodically broadcast on a broadcast channel (BCH). Minimum SI also includes a System Information Block 1 (SIB1), which defines the scheduling of other system information blocks and contains information for accessing the network node. SIB1 may also be referred to as Remaining Minimum SI (RMSI) and is periodically broadcast on a downlink shared channel (DL-SCH).

More specifically, in embodiments, a MIB on a public broadcast channel (PBCH) may provide a UE 150 with parameters (e.g., CORESET#0 configuration) for monitoring a public downlink control channel (PDCCH) for the schedule of a public downlink shared channel (PDSCH) that carries a SIB1. In embodiments, a PBCH may indicate that there is no associated SIB1, in which case the UE 150 may be pointed to another frequency in which to search for an SSB that is associated with a SIB1, and may be pointed to a frequency range where the UE 150 may assume no SSB associated with SIB1 is present. The indicated frequency range may be confined within a contiguous spectrum allocation of the same operator in which SSB is detected.

With continuing reference to FIG. 2, for each transmit-receive beam pair, the UE 150 measures a reference signal received power (RSRP). In embodiments, the beam pair with the maximum RSRP is selected. In embodiments, any beam pair with sufficient RSRP may be selected. Once the beam pair is identified, the UE 150 decodes the SSB of the selected network node transmit beam and decodes its contents, such as a MIB and/or a SIB1. As mentioned above, a MIB contains information of a cell for receiving further system information, and SIB1 defines the scheduling of other system information blocks and contains information for accessing the network node. Such information may be used by the UE 150 to establish a connection with the network apparatus 110.

In some examples, the characteristics of each of the transmit-receive beam pair may be mapped to TCI states. In one example, a transmit-receive beam pair may be mapped to a DL TCI state for DL communication from the network to the UE and a UL TCI state for UL communication from the UE to the network. In another example, a transmit-receive beam pair may be mapped to a joint TCI state for UL and DL communication between the network and the UE.

The examples of FIGS. 1 and 2 are merely illustrative. In embodiments, the number and direction of network node beams and the number and direction of UE beams may vary and may be different from those illustrated in FIGS. 1 and 2.

In some examples, it may be beneficial for a network to utilize dual connectivity and/or carrier aggregation in addition to beamforming to increase the bandwidth and bitrate for communication with UEs as will be discussed more fully below in connection with FIG. 3.

FIG. 3 is a diagram of an example embodiment a UE 310 in communications with an MN 320 and an SN 330. The UE 310 may be substantially similar to the UE 150 of FIG. 1. In embodiments, the MN 320 and/or the SN 330 may be a 5G NR node (e.g., gNB) or an LTE network node (e.g., eNB), among other types of nodes. In embodiments, the MN 320 and/or SN 330 may be base stations. The UE 310 may operate in a dual connectivity mode. Dual connectivity allows the UE 310 to simultaneously connect to two network nodes (e.g., the MN 320 and the SN 330 as shown).

In embodiments, the MN 320 connects to a core network, such as a 5G core (5GC), and provides a control plane connection between a UE 310 and the core network, while the SN 330 connects to the MN 320 (e.g., via an Xn interface) and provides additional resources for user plane traffic. In embodiments, the MN 320 handles signaling messages, such as RRC signaling messages. In embodiments, using signaling radio bearers (SRB) for LTE networks (e.g., SRB0, SRB1, and/or SRB2) and/or for 5G NR networks (e.g., SRB3), the SN 330 may handle signaling messages, such as RRC signaling messages, as well. As persons skilled in the art will understand, RRC is used by a node and a UE for various radio resource operations, such as, without limitation, connection management and mobility functions, among others. As used herein, the term “resource” may refer to radio resources, such as a physical resource block (PRB), a radio frame, a subframe, a time slot, a sub-band, a frequency region, a sub-carrier, a beam, etc. As used herein, the term “transmission” and/or “reception” may refer to, respectively, wirelessly transmitting and/or receiving via a wireless propagation channel on radio resources. Persons skilled in the art will understand RRC and SRB.

As further shown in the example of FIG. 3, carrier aggregation may be used in conjunction with dual connectivity. Carrier aggregation enables a UE 310 to simultaneously connect with multiple cells so as to operate at multiple frequencies at the same time. In embodiments, the multiple cells may be located at a single base station and/or at a common location (e.g., small cells or femtocells at a facility). One or more cells that may be usable by a UE under carrier aggregation may be referred to as a “cell group.” When carrier aggregation is used with dual connectivity, the MN and/or the SN may have a cell group. A cell group of a MN may be referred to as a master cell group (MCG), and a cell group of a 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 (SCell). The SCG includes a primary cell of a secondary cell group (PSCell) and may include one or more secondary cells (SCell). In the illustrated example of FIG. 3, the MN 320 includes one PCell 322 and one SCell 324. Similarly, the SN 330 includes one PCell 332 and one SCell 334. Each of the PCell 322, SCell 324, PCell 332, and SCell 334 may be operated by a network apparatus substantially similar to the network apparatus 110 of FIG. 1. Persons skilled in the art will understand the characteristics and functions of such cells and cell groups.

In some examples, the MN 320 and/or the SN 330 may utilize beamforming techniques to communicate with the UE 310 as discussed above with reference to FIGS. 1 and 2.

As explained above, a UE may travel from one area to another area, and thus handover or mobility procedures can be important to support continue communication of the UE with the network. Further, a more efficient handover process, such as LTM, can be beneficial in avoiding or at least reducing any disruption to the UE service as the UE moves from one cell coverage to another cell coverage.

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

In an aspect, each of the network apparatuses 420, 430, and 440 and the UE 410 may implement beamforming as discussed above with reference to FIG. 1. Further, each of the network apparatuses 420, 430, and 440 may transmit RSs, such as the SSBs discussed above with reference to FIG. 2, to facilitate signal measurements and/or reporting by a UE such as the UE 410. Further still, the UE 410 can be served by multiple cells concurrently, for example, using carrier aggregation and/or dual connectivity as discussed above with reference to FIG. 3.

To facilitate LTM, the network apparatus 420 (or the serving cell) may configure the UE 410 for signal measurements (e.g., Ll-RSRP) in a variety of ways. In a first example, the UE 410 may be provided with configurations for LI measurements of RSs under ServingCellConfig for its serving cell(s). In some instances, it may be useful to reuse inter-cell beam management (ICBM) mechanisms as defined in 3GPP Release 17. In a second example, the UE 410 may be provided with configurations for LI measurements under CellGroupConfig for candidate cell(s). In a third example, the UE 410 may be provided separately under ServingCellConfig for LI measurements of RSs for serving cell(s) and under CellGroupConfig for LI measurements of RSs for candidate cells(s). Persons skilled in the art will understand the characteristics and functions of such ServingCellConfig and CellGroupConfig.

To further facilitate beam indications for LTM, the UE 410 may be provided with beam indications associated with candidate cell(s) before a cell switch, after a cell switch, or as part of a cell switch command. Accordingly, there is a need to design an LTM framework to incorporate beam indications.

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

In the illustrated example of FIG. 4, the UE 410 may utilize various beams for communication. In order not to clutter the drawings of FIG. 4, only two beams 412 and 414 are illustrated. The beams 412 and 414 may be substantially similar to the beams discussed above with reference to FIGS. 1- 2. The network apparatus 420 (the serving cell) may activate, at the UE 410, a TCI state corresponding to the beam 412 for the candidate cell operated by the network apparatus 430. The network apparatus 420 may further activate, at the UE 410, a TCI state corresponding to the beam 414 for the candidate cell operated by the network apparatus 440. For LTM, the network apparatus 420 may indicate a cell operated by the network apparatus 430 as the target cell. As part of the cell switch, the UE 410 may switch to communicate with the network apparatus 430 (the target cell) as indicated by the dashed arrow. The UE 410 may communicate with the target cell using beam 412 corresponding to the TCI state activated by the serving cell. Mechanisms for LTM beam indications will be discussed more fully below with reference to FIGS. 5-7.

The examples of FIGS. 3 and 4 are merely illustrative. In embodiments, the number of PCells and SCells in an MN and/or in an SN, the number of candidate cells, and the number of activated TCI states (or beams) may vary and may be different from those illustrated in FIGS. 3 and 4.

FIGS. 5-7 are discussed in relation to each other to illustrate mechanisms for LTM beam indications using TCI states, e.g., to extend the unified TCI framework defined by 3 GPP.

FIG. 5 is a diagram of an example embodiment of operations for LTM. The operations are implemented among a UE 510, a serving cell 520, and a target cell 530 for LTM. In some examples, each of the UE 510, a serving cell 520, and a target cell 530 may implement the operation using an apparatus with components as shown in FIG. 11. One or more of the following operations may be implemented in connection with the operations of the present disclosure, such as the examples discussed above with reference to FIGS. 1-4. The UE 510 may be similar to the UEs 150, 310, and/or 410. The serving cell 520 and the target cell 530 may be similar to the network apparatuses 110, 420, and/or 430. As illustrated, FIG. 5 includes a number of enumerated steps, but aspects of the operations in FIG. 5 may include additional steps before, after, and in between the enumerated steps. In some aspects, one or more of the enumerated steps may be omitted or performed in a different order.

In some examples, carrier aggregation may be used among the UE 510, the serving cell 520, and the target cell 530 (if the target cell is an SCell. For instance, the serving cell 520 may be a PCell similar to the PCells 322 and/or 332, and the target cell 530 can be a PCell or an SCell similar to the SCells 324 ad/or 334. In other words, the LTM operations of FIG. 5 can be used to switch the UE 510 from a serving PCell to a target PCell or from a serving PCell to a target SCell. However, the initiation or triggering of the cell switch may be from a serving PCell. In some examples, inter- cell beam management may be used among the UE 510, the serving cell 520, and the target cell 530 (where the target has different PCI than a serving cell). In other words, the inter-cell beam management operations of FIG. 5 can be used prior the to the switching the UE 510 from a serving PCell to a target cell. In general, the LTM operations described herein may be applicable for PCell and/or SCell and or cell with different PCI than a/the serving cell in a cell switch or handover process.

As shown in FIG. 5, at 502, the serving cell 520 transmits, and the UE 510 receives a configuration. The configuration may be received, for example, during an LTM preparation phase. The configuration may include configurations of one or more cells, for example, including a 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 FIG. 6.

FIG. 6 is a diagram of an example configuration 600 for provisioning LTM. The configuration 600 may be referred to as a CellGroupConfig. In general, the configuration 600 may refer to set of cells that are configured for LTM operation (this may include one or more serving cells and/or one or more candidate cells). The configuration 600 may include a configuration for each of a plurality of cells associated with LTM. In the illustrated example of FIG. 6, the configuration 600 includes a configuration 610, which may be referred to as a ServingCellConfig, for a PCell identified by an index 0 and an LTM index 0. The configuration 600 further includes a configuration 620, which may be referred to as a ServingCellConfig, for a candidate cell identified by an LTM index 1. The configuration 600 further includes a configuration 630, which may be referred to as a ServingCellConfig, for a candidate cell identified by an LTM index 2. The cells may have other index values depending on which of the cell is serving the UE (thus providing the configuration) e.g., the LTM cell (with index 2) may be a PCell of another UE. The LTM index referred herein is an example and the LTM cell may be referred with a cell identifier, LTM configuration index or any identifier that can be used to refer to the specific cell. The serving cell (e.g., PCell) may also be an LTM cell (and can be referred with a LTM index or the like). Each of the configurations 610, 620, and 630 may include a TCI configuration for a respective cell. For instance, as further shown in FIG. 6, the configuration 610 includes a TCI configuration 614 including a TCI state list 612 for a PCell (e.g., the serving cell 520) that is currently serving a UE (e.g., the UE 510). The configuration 620 includes be a TCI configuration 624 including a TCI state list 622 for an LTM candidate identified by LTM index 1. In a similar way, the configuration 630 includes a TCI configuration 634 including a TCI state list 632 for an LTM candidate identified by LTM index 2. Each of the TCI state lists 612, 622, and 632 may include one or more TCI states (e.g., 1, 2, 3, 4, 5, 6 or more). In an aspect, each cell (e.g., serving cell, candidate cell) may have independent configuration of TCI states or TCI state lists. As such, a TCI state with a certain value (e.g., 1) for one cell may refer to cell specific (or different) transmission and/or reception characteristic(s) a TCI state with the same value for another cell. In other words, TCI state ID# of a cell 1 may comprise of different information than the TCI state ID# of cell 2. In general, a TCI state may include any suitable parameters related to a beam or a transmission.

In an aspect, configuration of TCI state list(s) (or TCI state pool) associated with each candidate cell may be provided to the UE 510, e.g., in the LTM preparation phase. In one example, the TCI state lists may be provided/updated using RRC. In one example, such a configuration may be part of a reference RRC configuration which the UE 510 may retain and/or maintain across multiple cell switches. As shown in FIG. 6, configuration of TCI state lists respective to each configured LTM candidate cell may be provided under a cell group configuration (CellGroupConfig), or as part of other RRC configuration, and each LTM cell can be referred using an LTM candidate cell identifier within the serving cell. In one example, each TCI state list can be referred using an LTM candidate cell identifier (or LTM index, or LTM configuration ID) within the serving cell. In another example, configuration of TCI state list(s) respective to each configured LTM candidate cell may be provided outside of any cell group configuration. In another example, configuration of TCI state list(s) respective to each configured LTM candidate cell may be provided using RRC signaling. For instance, an LTM-specific configuration message may be used to provide LTM candidate cell TCI state configurations. The examples of FIG. 6 are merely illustrative. In embodiments, the number of LTM candidate cells and/or the LTM indices indicated in a configuration may vary and may be different from those illustrated in FIG. 6.

Returning to FIG. 5, at 504, the serving cell 520 transmits, and the UE 510 receives a MAC-CE (a candidate cell/LTM cell TCI state activation MAC-CE or generally a message) including an indication of a candidate cell (e.g., a neighboring cell/LTM cell as discussed above with reference to FIG. 4) and an activation of one or more TCI states for the candidate cell. The MAC-CE may include a candidate cell ID to indicate the candidate cell. The one or more TCI states activated for the candidate cell may be referred to as an activated TCI State list (a candidate cell-specific activated TCI list). The one or more activated TCI states may include at least a subset of the one or more TCI configured states configured for the candidate cell at 502. In some instances, the serving cell 520 may exclude at least one of the one or more configured TCI states for the candidate cell. That is, at least one of the configured TCI states for the candidate cell may remain deactivated. In other instances, the serving cell 520 can activate all of the one or more configured TCI states for the candidate cell. The MAC-CE for the TCI state activation may be in a variety of formats, for example, as discussed below with reference to FIG. 7.

FIG. 7 is a diagram of an example TCI state activation MAC-CE 700 for a candidate cell to support LTM. As shown in FIG. 7, the MAC-CE 700 includes a serving cell identifier (ID)/LTM ID (e.g., LTM index, LTM configuration ID or any ID that identifies the candidate/LTM cell) field 702, an S/L field 704, and a TCI state list field 710. The serving cell ID/LTM ID field 702 may have a length of 5 bits and may indicate a serving cell ID identifying a serving cell or an LTM ID identifying a candidate cell for which the MAC-CE 700 applies. 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 the serving cell ID/LTM ID field 702 includes a value for a serving cell ID or an LTM ID (for a candidate cell) for which the MAC-CE 700 applies. For instance, 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 1 for a cell identified by the serving cell ID/LTM ID field 702 for 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 a candidate cell identified by the LTM ID.

As further shown in FIG. 7, the MAC-CE 700 includes a plurality of reserved fields 701 shown by R, a DL bandwidth part (BWP) ID field 703, a UL BWP ID field 705, a plurality of Pi fields 706 shown by Pi to Ps (e.g., i varies from 1 to 8), and a plurality of D/U fields 707 shown by D/U. In order not to clutter the drawing of FIG. 7, only one of the reserved fields is labelled by 701, only one of the Pi fields is labelled by 706, and only one of the D/U fields is labelled by 707.

In an example, if the indicated serving cell in the serving cell ID/LTM ID (e.g., an LTM index, an LTM configuration ID, or any ID that identifies the candidate/LTM cell) field 702 is configured as part of a simultaneousU-TCI-UpdateListl, simultaneousU-TCI-UpdateList2, simultaneousU-TCI-UpdateList3 or simultaneousU-TCI-UpdateList4 as specified in 3GPP TS 38.331 document, this MAC-CE 700 applies to all the serving cells in the set simultaneousU-TCI-UpdateListl , simultaneousU-TCI-UpdateList2, simultaneousU-TCI- UpdateList3 or simultaneousU-TCI-UpdateList4, respectively, for the serving cell.

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

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

The Pi field 706 indicates whether each TCI codepoint has multiple TCI states or single TCI state. If Pi field 706 is set to 1, it indicates that the i^th TCI codepoint includes a DL TCI state and a UL TCI state. If Pi field 706 is set to 0, it indicates that the i^th TCI codepoint includes a DL/joint TCI state or a UL TCI state. The codepoint to which a TCI state is mapped is determined by its ordinal position among all the TCI state ID fields in the TCI state list field 710.

The D/U fields 707 indicate whether the TCI state ID in the same octet is for joint/ downlink or uplink TCI state. If this field is set to 1, the TCI state ID in the same octet is for uplink, or vice versa.

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

The reserved field 701 is a reserved bit and may be set to 0.

Persons skilled in the art will understand simultaneousU-TCI-UpdateListl, simultaneousU- TCI-UpdateList2, simultaneousU-TCI-UpdateList3, simultaneousU-TCI-UpdateList4, DL BWP, and UL BWP.

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

In an example, the unified TCI state activation/ deactivation MAC-CE as defined in 3 GPP TS 38.321 document may be modified as shown in the MAC-CE 700 of FIG. 7. In an aspect, the serving cell ID in the unified TCI state activation/deactivation MAC-CE may be re-interpreted to include a serving cell ID or an LTM configuration ID (e.g., an ID to indicate an LTM candidate cell including the current serving cell). The unified TCI state activation/deactivation MAC-CE may include a bitfield (e.g., the S/L field 704) on which the interpretation may depend. For instance, the bitfield in the MAC-CE indicates whether the TCI state activation is for the serving cell (serving cell ID, S) or an LTM candidate cell (LTM configuration index, ‘L’). If the bitfield indicates S, the activation is for the serving cell ID and for the serving cell beam management (e.g., for intra/inter-cell beam management), Alternatively, if the bitfield indicates L, the active TCI States in the MAC-CE are for the LTM candidate cell (e.g., including the current serving cell) that the field indicates.

The examples of FIG. 7 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.

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

Returning to FIG. 5, at 506, the UE 510 and the serving cell 520 may communicate with each other. In some examples. The serving cell 520 may transmit, and the UE 510 may receive signal measurement configuration(s) (e.g., Ll-RSRP measurement configurations for SSBs, CSI-RSs, DL RSs, and/or any RSs). In response, the UE 510 may transmit, and the serving cell 520 may receive signal measurement report(s) as discussed above. In general, the serving cell 520 may serve the UE 510 by communicating any suitable communication signals with the UE 510 at 506.

At 508, the serving cell 520 transmits, and the UE 510 receives, via lower layer signaling (e.g., via medium access control (MAC) or physical layer signaling, L1/L2 signaling), a cell switch command indicating the candidate cell (for which the one or more TCI states are activated at 504) as a target cell (shown by the target cell 530). For instance, the cell switch command may include an indication of a target cell ID corresponding to the candidate cell ID in the MAC-CE at 504. The serving cell 520 may select the candidate cell using any suitable mechanisms, for example, based on a best signal quality from the candidate cell among a set of candidate cells.

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

At 512, in response to the cell switch command, the UE 510 switches communication 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.

In one aspect, the TCI state activation for the candidate cell at 504 may include a single (only one) activated TCI state, and the cell switch command at 508 may exclude any TCI state indication or may indicate that no TCI state is provided. In this regard, when the UE 510 receives the cell switch command without any TCI state or indication that no TCI state is provided, the UE 510 considers that the cell switch command implicitly indicated the single activated TCI state. Accordingly, the UE 510 may apply the single activated TCI state at 512 for communication 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 states, the UE 510 may consider a TCI state is indicated (for a cell switch) when the TCI state in the cell switch command is the same as (or matches) the activated TCI state ID.

In an aspect, the UE 510 may consider the activated TCI States for the LTM cell received in a MAC-CE (e.g., at 504) as valid upon reception of the MAC-CE. In an aspect, when the UE 510 subsequently receives another MAC-CE activating (or updating) TCI states for the same LTM cell, the earlier activated TCI states may be updated by the TCI states activated by the latest MAC-CE.

In an aspect, the UE 510 may be configured to receive one or more MAC-CEs that provide TCI state activation. The configuration can be based on a UE capability. The UE capability may indicate, for example, 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 lists as described herein. In one example, there may be a maximum number (or threshold number) of N activated TCI states across the different LTM candidate cells supported by the UE 510. In an example, the value N may include the active TCI states used for cell beam management at the current serving cell. In other words, the value N may be a total number of active TCI states supported by the UE 510 for the current serving cell and any other LTM candidate cells. In another example, the value N may exclude the active TCI states used for cell beam management at the current serving cell. In other words, N may be a total number of active TCI states supported by the UE 510 for LTM candidate cells.

In an aspect, a DCI -based beam indication may be used to indicate a cell switch command (e.g., at 508) when MAC-CE -based TCI state activation(s) are provided for LTM as described herein. In a first example, a DCI-based beam indication may include an LTM index, LTM configuration ID, or the like (e.g., additional PCI index which is a logical index for the 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 FIG. 7, each of the TCI state IDs in the TCI state list field 710 may be referenced by a TCI codepoint according to the order of the TCI state IDs in the TCI state list field 710. That is, a TCI codepoint having a value of 0 may refer (or point) to the TCI state ID 1 in the TCI state list field 710, a TCI codepoint having a value of 1 may refer (or point) to the TCI state ID 2 in the TCI state list field 710, and so on, assuming each TCI code point includes one TCI state. To indicate the activated TCI state ID 2 (in the TCI state list field 710) for a cell switch to a candidate cell identified by the LTM ID in the serving cell ID/LTM field 702, the DCI-based beam indication may include a TCI codepoint value of 2. In a second example, the DCI-based beam indication may include an indication of an LTM candidate pool/cell ID and a TCI codepoint referencing at least one of the one or more activated TCI states in the TCI state list field 710. In a third example, the DCI-based beam indication may include an LTM flag indicating that the DCI beam indication refers to an LTM candidate cell TCI state list and not a serving cell beam management TCI state list.

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

In an aspect, upon receiving and applying the cell switch command, the UE 510 may determine to use the activated TCI state list (activated at 504) for the new serving cell (e.g., the target cell 530) for which the cell switch command is applied. As an example, when the UE 510 enters the new target cell (e.g., the target cell 530), the UE 510 considers the “activated TCI state list” as valid for intra-cell beam management. In other words, the list is the activated TCI State list for the current serving cell (e.g., a PCell) for which the UE 510 performed the switch. The activated TCI states in the activated TCI state list may refer to the TCI states provided in the RRC configuration. As an example, the UE retains the list of activated TCI states after the cell switch and the list of TCI states (RRC configured) from which the TCI States were activated. In another example, if the activated TCI State list (activated at 506) for the serving cell 520 is associated with more than one PCIs, when the UE 510 enters the new target cell, the UE 510 considers the “activated TCI state list” as valid for inter-cell beam management and intra-cell beam management. Beam management may generally refer to processes and/or mechanisms that are related to forming, controlling, and/or detecting beams. Beam management may include various phases, for example, during an initial access by a UE or while the UE is in a connected mode. In inter-cell beam management the UE may be configured to communicate with a cell that has a different PCI than the serving cell while maintaining connection to the serving cell.

In an aspect, when the UE 510 applies the MAC-CE that is used to activate TCI states for an LTM cell (e.g., at 504), the activated TCI states are considered to be valid until the cell switch command is applied at 508. For the cell (e.g., the target cell 530) which the cell switch is triggered/signaled, the list (of the activated 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).

In an aspect, the UE 510 may retain a TCI state list activated by the source cell (the previous serving cell 520) while operating in the target cell 530. The activated TCI state list may be for the previous serving cell 520, any previous serving cell, or other candidate cells. For instance, the UE 510 may store the activated TCI state list at a memory (e.g., the memory 1150) of the UE 510 upon receiving the activated TCI state list and may not overwrite or delete the stored activated TCI state list. In an aspect, whether the active TCI states are maintained and/or retained at the UE 510 after the cell switch can be configured. The configuration can be cell specific. For instance, the UE may receive a configuration (e.g., from the serving cell 520) or indication indicating whether the active TCI state list (for the target cell and/or other candidate cells for which the TCI states have been activated) is to be deactivated or maintained after the UE 510 enters the target cell 530. In one aspect, the UE 510 may receive this configuration or indication as part of the cell switch command (e.g., in DCI) or an RRC configuration (e.g., an RRC pre-configuration).

In a further aspect, a current serving cell ID (which can also be identified by an LTM configuration index or an LTM index) can be referred with a MAC-CE that activates TCI states for intra-cell beam management. In an example, if the current serving cell 520 is referred in a MAC-CE that activates TCI state(s) using LTM specific index (e.g., the current serving cell is referred to as a or referred with a candidate cell (LTM) index), the UE 510 determines that the TCI state(s) provided in the activation MAC-CE are activated upon the UE 510 applying the cell switch to the new target cell 530. In other words, the serving cell may be configured and activated with TCI states that are for LTM operation (and at the same time the serving cell may have an activated TCI State list for intra-cell beam management).

The examples of FIG. 5 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 TCI state activation in each candidate cell TCI state activation MAC-CE, and/or the number of TCI states for activation for each candidate cell may vary and may be different from those illustrated in FIG. 5. In some examples, the serving cell 520 may transmit one MAC-CE to activate TCI state(s) for each LTM candidate cell. In other examples, the serving cell 520 the serving cell 520 may transmit one MAC-CE to activate TCI state(s) for multiple LTM candidate cells. In some examples, a candidate cell TCI state activation MAC-CE may include a candidate cell-specific TCI state active list for each candidate cell. In some examples, a candidate cell TCI state activation MAC-CE may include a candidate cell list include multiple candidate cell IDs and a separate TCI state active list for each of the multiple candidate cells. In some examples, a candidate cell TCI state activation MAC-CE may be a modified or extended unified TCI state activation MAC-CE as defined by 3GPP. In other examples, a candidate cell TCI state activation MAC-CE can be a MAC- CE (or generally a message) identified by an ID specific for TCI state activation for LTM candidate cells. FIG. 8 is a flow diagram of example operations of a UE, such as the UEs 150, 310, 410, and/or 510, for LTM. The operations of FIG. 8 may include similar mechanisms as discussed above with reference to FIGS. 5-7. As illustrated, FIG. 8 includes a number of enumerated steps, but aspects of the operations in FIG. 8 may include additional steps before, after, and in between the enumerated steps. In some aspects, one or more of the enumerated steps may be omitted or performed in a different order.

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

In an aspect, the MAC-CE includes a first field and a second field to indicate whether information in the first field is for the serving cell or the candidate cell. For instance, the second field may be similar to the S/L field 704 in the MAC-CE 700 of FIG. 7 for providing conditional interpretation of the first field. In an aspect, the MAC-CE includes a first value and a second value to indicate that the first value identifies the candidate cell. In an aspect, the MAC-CE includes a value to indicate that the one or more TCI states are activated for the candidate cell. In an aspect, the MAC- CE includes a candidate cell-specific TCI state list including an indication of the candidate cell (e.g., an LTM ID) and the activation of the one or more TCI states (for the candidate cell).

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

In an aspect, the receiving the cell switch command includes receiving DCI including an indication of the candidate cell and a TCI codepoint referencing the at least one of the one or more TCI states. In an aspect, receiving the cell switch command includes receiving DCI including an indication of a candidate cell activated TCI state list including the candidate cell and a TCI codepoint referencing the at least one of the one or more TCI states. In an aspect, the receiving the cell switch command includes receiving 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. At 806, the operations include switching, in response to the cell switch command, communication to the target cell. The switching to the target cell includes communicating with the target cell by applying at least one of the one or more TCI states. In an aspect, carrier aggregation may be used for communication with the UE as discussed above with reference to FIG. 3 (if the target cell is an SCell). In such an aspect, the serving cell may be a PCell and the candidate cell may be a candidate PCell. Accordingly, the switching communication to the target cell may refer to switching communication from the serving PCell to the target PCell. In another aspect, the serving cell may be a PCell and the candidate cell may be a candidate PCell. Accordingly, the switching communication to the target cell may refer to switching communication from a serving PCell to the target SCell.

In an aspect, the cell switch command at 804 further includes a reference (e.g., a TCI codepoint) to the at least one of the one or more TCI states (activated at 802). In a further example it may be configurable whether the cell switch command provides the beam indication/TCI state indication in a form a TCI codepoint or TCI State ID. In an example, the cell switch command may have indication whether the at least one TCI State is indicated using a TCI codepoint or the TCI state ID (or IDs). In one example if the separate TCI states (separate TCI states for uplink and downlink) are indicated the cell switch command may refer to a TCI codepoint referring to the TCI States (e.g., for less indication overhead)). In one example if the separate TCI states (separate TCI states for uplink and downlink) are indicated the cell switch command, the cell switch TCI state IDs for downlink and uplink. The TCI states may be listed in the order of DL TCI State ID and UL TCI state ID. In one example, the DCI that schedules the cell switch command may comprise a TCI codepoint that indicates the TCI state(s) for the target cell. The cell switch command (in any of the embodiments) that provides indication of a TCI State (e.g., a beam indication) may refer to any MAC CE that activates TCI States for LTM based beam indication (and/or for further communication in the target cell).

In an aspect, the cell switch command at 804 further includes a reference to a TCI state, and the applying the 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 the at least one of the one or more TCI states. As an example, if the cell switch command indicates a TCI state ID 2 and the one or more activated TCI states includes the same TCI state ID 2, the UE may apply TCI state ID 2 for communication with the target cell. If, however, the cell switch command indicates a TCI state ID 2 and the one or more activated TCI states do not include a TCI state ID 2, the UE may not apply the TCI state ID2 as indicated by the cell switch command. In this case, the UE may determine to trigger random access procedure on the candidate cell. Alternatively, the UE may use the TCI state ID 2 as target/indicated TCI State ID and determine that the TCI State ID (#2) is not known TCI state for the UE and further apply longer beam application time (i.e., time after which the UE is assumed to use/apply the new TCI state). Beam application time may comprise of performing one or more measurements on the DL RS indicated by the TCI state.

In an aspect, the UE further performs intra-cell beam management in the target cell based on the one or more TCI states. In an aspect, the one or more TCI states are associated with more than one PCIs, 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 may include forming, controlling, and/or detecting beams.

In an aspect, the UE may further retain, while operating in the target cell, a TCI state list activated by the serving cell (e.g., a previous source cell) at 802. In an aspect, the retaining, while operating in the target cell, the TCI state list activated by the serving cell is based on a configuration including an indication to retain the TCI state list activated by the previous serving cell. In an aspect, the configuration is a cell-specific configuration. In one aspect, the cell switch command at 804 includes the configuration. In another aspect, the UE may further receive the configuration in an RRC configuration (e.g., a cell-specific RRC configuration).

In an aspect, the UE may further 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 a number of the one or more TCI states in the MAC-CE for the candidate cell or a number of TCI states activated across multiple cells is based on the UE capability.

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

FIG. 9 is a flow diagram of example operations of a network apparatus, such as the network apparatus 110, the MN 320, the PCell 322 (e.g., a PCell network node), a CU, a DU, the network apparatuses 420, 430, 440, and/or the serving cell 520 (e.g., a serving cell network node). The operations of FIG. 9 may include similar mechanisms as discussed above with reference to FIGS. 5-7. As illustrated, FIG. 9 includes a number of enumerated steps, but aspects of the operations in FIG. 9 may include additional steps before, after, and in between the enumerated steps. In some aspects, one or more of the enumerated steps may be omitted or performed in a different order.

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

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 an aspect, the cell switch command further 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 may expect the UE to utilize the one or more TCI states (activated at 902) upon switching to the target cell. At 906, the operations include performing a handover of the UE to the target cell responsive to the cell switch command. The handover may include forwarding information and/or any pending data associated with the UE 510 to the target cell.

FIG. 10 illustrates an example embodiment of a block diagram of example components of a UE or of a network apparatus. For instance, the UE may correspond to theUE 150, 310, 410, or 510, and the network apparatus may correspond to the network apparatus 110, the MN 320, the PCell 322 (e.g., a PCell network node), the network apparatuses 420, 430, 440, or a network apparatus (which may be a network node, a CU, or a DU) of the serving cell 520. The apparatus includes an electronic storage 1110, a processor 1120, a memory 1150, and a network interface 1140. The various components may be communicatively coupled with each other. The processor 1120 may be and may 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-Chip (SoC), or any other type of processor. The memory 1150 may be a volatile type of memory, e.g., RAM, or a non-volatile type of memory, e.g., NAND flash memory. The memory 1150 includes computer- readable instructions that are executable by the processor 1120 to cause the apparatus to perform various operations, including beams indications (e.g., TCI state pre-activations and/or TCI state indication) for LTM as discussed herein.

The electronic storage 1110 may be and include any type of electronic storage used for storing data, such as hard disk drive, solid state drive, and/or optical disc, 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 relating to 5G NR standards, among other data. The network interface 1140 may implement wireless networking technologies such as 5GNR, Wi-Fi 6, and/or other wireless networking technologies, and may include one or more arrays of radiating elements, such as those described in connection with FIGS. 1-7.

The components shown in FIG. 10 are merely examples, and persons skilled in the art will understand that an apparatus includes other components not illustrated and may include multiples

RECTIFIED SHEET (RULE 91) ISA/EP of any of the illustrated components. Such and other embodiments are contemplated to be within the scope of the present disclosure.

Further embodiments of the present disclosure include the following examples.

Example 1 includes a method performed by a user equipment apparatus, the method including receiving, from a serving cell, a medium access control-control element (MAC-CE) including 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 lower layer signaling (e.g., via medium access control (MAC) or physical layer signaling, L1/L2 signaling), a cell switch command indicating the candidate cell as a target cell; and switching, in response to the cell switch command, communication to the target cell, where the switching includes communicating with the target cell by applying at least one of the one or more TCI states.

In Example 2, the method of example 1 can optionally include where the MAC-CE includes a first field; and a second field to indicate whether information in the first field is for the serving cell or the candidate cell.

In Example 3, the method of any one of examples 1-2 can optionally include where the MAC-CE includes a first value; and a second value to indicate that the first value identifies the candidate cell.

In Example 4, the method of any one of examples 1-3 can optionally include where the MAC-CE includes a candidate cell-specific TCI state list including the one or more TCI states.

In Example 5, the method of any one of examples 1-4 can optionally include where the cell switch command further includes a reference to the at least one of the one or more TCI states.

In Example 6, the method any one of examples 1-5 can optionally include where the receiving the cell switch command includes receiving downlink control information (DCI) including an indication of the candidate cell and a TCI codepoint referencing the at least one of the one or more TCI states.

In Example 7, the method of any one of examples 1-5 can optionally include where the receiving the cell switch command includes receiving downlink control information (DCI) including an indication of a candidate cell activated TCI list including the candidate cell and a TCI codepoint referencing the at least one of the one or more TCI states.

In Example 8, the method of any one of examples 1-5 can optionally include where the receiving the cell switch command includes receiving downlink control information (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.

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

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

In Example 11, the method of any one of examples 1-9 can optionally include where the one or more TCI states are associated with more than one physical cell identifiers (PCIs), and where 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.

In Example 12, the method of any one of examples 1-11 can optionally include retaining, while operating in the target cell, a TCI state list activated by the serving cell. In Example 13, the method of any one of examples 1-12 can optionally include where the retaining, while operating in the target cell, the TCI state list activated by the serving cell is based on a configuration including an indication to retain the TCI state list activated by the serving cell.

In Example 14, the method of any one of examples 1-13 can optionally include where the configuration is a cell-specific configuration.

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

In Example 16, the method of any one of examples 1-14 can optionally include where the cell switch command includes the configuration.

In Example 17, the method of any one 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), where at least one of a number of the one or more TCI states activated in the MAC- CE for the candidate cell or a number of TCI states activated across multiple cells at the user equipment apparatus is based on the user equipment capability.

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

In Example 19, the method of any one of examples 1-18 can optionally include receiving a configuration including an indication of one or more candidate cells for low layer triggered mobility and a TCI state list for each of the one or more candidate cells.

In Example 20, the method of any one of examples 1-19 can optionally include where the serving cell is a primary cell. Example 21 includes an apparatus including at least one processor; and at least one memory storing instructions which, when executed by the at least one processor, cause a user equipment apparatus at least to perform the method of any one of examples 1-20.

Example 22 includes an apparatus including means at least to perform the method of any one of examples 1-20.

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

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

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

In Example 26, the method of any one of examples 24-25 can optionally include where the MAC- CE includes a first value; and a second value to indicate that the first value identifies the candidate cell.

In Example 27, the method of any one of examples 24-26 can optionally include where the MAC- CE includes a candidate cell-specific TCI state list including the one or more TCI states. In Example 28, the method of any one of examples 24-27 can optionally include where the cell switch command further includes a reference to the at least one of the one or more TCI states.

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

In Example 30, the method of any one of examples 24-28 can optionally include where the transmitting the cell switch command includes transmitting downlink control information (DCI) including an indication of a candidate cell activated TCI list including the candidate cell and a TCI codepoint referencing the at least one of the one or more TCI states.

In Example 31, the method of any one of examples 24-28 can optionally include where the transmitting the cell switch command includes transmitting downlink control information (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.

In Example 32, the method of any one of examples 24-31 can optionally include transmitting a configuration including an indication of whether the user equipment apparatus is to retain an activated TCI state list activated after switching to the target cell.

In Example 33, the method of any one of examples 24-32 can optionally include where the configuration is an RRC configuration.

In Example 34, the method of any one of examples 24-33 can optionally include where the configuration is a cell-specific configuration.

In Example 35, the method of any one of examples 24-33 can optionally include where the cell switch command includes a configuration including an indication of whether the user equipment apparatus is to retain an activated TCI state list activated after switching to the target cell. In Example 36, the method of any one of examples 24-35 can optionally include receiving, from the UE, an indication of a UE capability (e.g. , indicating a threshold number of activated TCI states supported by the UE); and configuring a number of TCI states to be activated across one or more cells for the UE based on the UE capability.

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

In Example 38, the method of any one of examples 24-37 can optionally include transmitting a configuration including an indication of one or more candidate cells for low layer triggered mobility and a TCI state list for each of the one or more candidate cells.

Example 39 includes an apparatus including at least one processor; and at least one memory storing instructions which, when executed by the at least one processor, cause the network apparatus at least to perform the method of any one of examples 24-38.

Example 40 includes an apparatus including means at least to perform the method of any one of examples 24-38.

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

The embodiments and aspects disclosed herein are examples of the present disclosure and may be embodied in various forms. For instance, although certain embodiments herein are described as separate embodiments, each of the embodiments herein may be combined with one or more of the other embodiments herein. Specific structural and functional details disclosed herein are not to be interpreted as limiting, but 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 virtually any appropriately detailed structure. Like reference numerals may refer to similar or identical elements throughout the description of the figures.

The phrases “in an aspect,” “in aspects,” “in various aspects,” “in some aspects,” or “in other aspects” may each refer to one or more of the same or different aspects in accordance with this present disclosure. The phrase “a plurality of’ may refer to two or more.

The phrases “in an embodiment,” “in embodiments,” “in various embodiments,” “in some embodiments,” or “in other embodiments” may each refer to one or more of the same or different embodiments in accordance with the present disclosure. A phrase in the form “A or B” means “(A), (B), or (A and B).” A phrase in the form “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).”

Any of the herein described methods, programs, algorithms or codes may be converted to, or expressed in, a programming language or computer program. The terms “programming language” and “computer program,” as used herein, each include any language used to specify instructions to a computer, and include (but is not limited to) the following languages and their derivatives: Assembler, Basic, Batch files, BCPL, C, C+, C++, Delphi, Fortran, Java, JavaScript, machine code, operating system command languages, Pascal, Perl, PL1, Python, scripting languages, Visual Basic, metalanguages which themselves specify programs, and all first, second, third, fourth, fifth, or further generation computer languages. Also included are database and other data schemas, and any other meta-languages. No distinction is made between languages which are interpreted, compiled, or use both compiled and interpreted approaches. No distinction is made between compiled and source versions of a program. Thus, reference to a program, where the programming language could exist in more than one state (such as source, compiled, object, or linked) is a reference to any and all such states. Reference to a program may encompass the actual instructions and/or the intent of those instructions.

While aspects of the present disclosure have been shown in the drawings, it is not intended that the present disclosure be limited thereto, as it is intended that the present disclosure be as broad in scope as the art will allow and that the specification be read likewise. Therefore, the above description should not be construed as limiting, but merely as exemplifications of particular aspects. Those skilled in the art will envision other modifications within the scope and spirit of the claims appended hereto.

Claims

CLAIMS:

1. A user equipment apparatus comprising: at least one processor; and at least one memory storing instructions which, when executed by the at least one processor, cause the user equipment apparatus at least to: receive, from a serving cell, a medium access control-control element (MAC-CE) including an indication of a candidate cell and an activation of one or more transmission configuration indicator (TCI) states for the candidate cell; receive, from the serving cell via lower layer signaling, a cell switch command indicating the candidate cell as a target cell; and switch, in response to the cell switch command, communication with the serving cell to communication with the target cell, wherein the communication with the target cell comprises communicating with the target cell by applying at least one of the one or more TCI states.

2. The user equipment apparatus of claim 1, wherein the MAC-CE includes: a first field; and a second field to indicate whether information in the first field is for the serving cell or the candidate cell.

3. The user equipment apparatus of claim 1, wherein the MAC-CE includes: a first value; and a second value to indicate that the first value identifies the candidate cell.

4. The user equipment apparatus of claim 1 , wherein the MAC-CE includes a candidate cell-specific TCI state list including the one or more TCI states.

5. The user equipment apparatus of claim 1, wherein the cell switch command further includes a reference to the at least one of the one or more TCI states.

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

7. The user equipment apparatus of claim 1, wherein the instructions when executed by the at least one processor, further cause the user equipment apparatus at least to receive the cell switch command by: receiving downlink control information (DCI) including an indication of a candidate cell activated TCI list including the candidate cell and a TCI codepoint referencing the at least one of the one or more TCI states.

8. The user equipment apparatus of claim 1, wherein the instructions when executed by the at least one processor, further cause the user equipment apparatus at least to receive the cell switch command by: receiving downlink control information (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.

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

10. The user equipment apparatus of claim 1, wherein the one or more TCI states are associated with more than one physical cell identifiers (PCIs), and wherein the instructions when executed by the at least one processor, further cause the user equipment apparatus at least to: perform at least one of intra-cell beam management or inter-cell beam management in the target cell based on the one or more TCI states.

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

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

13. A method performed by a user equipment apparatus, the method comprising: receiving, from a serving cell, a medium access control-control element (MAC-CE) including 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 lower layer signaling, a cell switch command indicating the candidate cell as a target cell; and switching, in response to the cell switch command, communication with the serving cell to communication with the target cell, wherein the communication with the target cell comprises communicating with the target cell by applying at least one of the one or more TCI states.

14. The method of claim 13, wherein the MAC-CE includes: a first field; and a second field to indicate whether information in the first field is for the serving cell or the candidate cell.

15. The method of claim 13, wherein the MAC-CE includes: a first value; and a second value to indicate that the first value identifies the candidate cell.

16. The method of claim 13, wherein the MAC-CE includes a candidate cell-specific TCI state list including the one or more TCI states.

17. The method of claim 13, wherein the cell switch command further includes a reference to the at least one of the one or more TCI states.

18. The method of claim 13, wherein the receiving the cell switch command comprises: receiving downlink control information (DCI) including an indication of the candidate cell and a TCI codepoint referencing the at least one of the one or more TCI states.

19. The method of claim 13, wherein the receiving the cell switch command comprises: receiving downlink control information (DCI) including an indication of a candidate cell activated TCI state list including the candidate cell and a TCI codepoint referencing the at least one of the one or more TCI states.

20. The method of claim 13, wherein the receiving the cell switch command comprises: receiving downlink control information (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: wherein the one or more TCI states are associated with more than one physical cell identifiers (PCIs), performing intra-cell beam management in the target cell based on the one or more TCI states.

22. The method of claim 13, wherein the one or more TCI states are associated with more than one physical cell identifiers (PCIs), and wherein the method further comprises: performing at least one of intra-cell management or inter-cell management in the target cell based on the one or more TCI states.

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

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

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

26. A method performed by a network apparatus, the method comprising: transmitting, to a user equipment apparatus, a medium access control-control element

(MAC-CE) including an indication of a candidate cell and an activation of one or more transmission configuration indicator (TCI) states for the candidate cell; and transmitting, to the user equipment apparatus via lower layer signaling, a cell switch command indicating the candidate cell as a target cell; and performing a handover of the user equipment apparatus to target cell responsive to the cell switch command.