Performing L1 / L2 inter-cell mobility

Abstract

An embodiment includes a method for a user equipment (UE) configured to communicate with a radio access network (RAN) node having a central unit (CU) and a distributed unit (DU) that provides a serving cell for the UE. Such a method includes receiving a lower layer signaling message from the DU indicating that the UE should perform L1 / L2-based inter-cell mobility to a first candidate cell provided by the candidate DU. The lower layer signaling message includes an indicator or identity of the first candidate cell and an indication of a first TCI state to be used by the UE to communicate with the first candidate cell. Such a method includes performing an L1 / L2 mobility procedure toward the first candidate cell and communicating in the first candidate cell based on the first TCI state. Other embodiments include complementary methods for the serving and candidate DUs, as well as UEs and DUs configured to perform such methods.

Description

[Technical Field]

[0001] The present application relates generally to the field of wireless networks, and more particularly to improving the mobility of user equipment (UE) across multiple cells in a wireless network, and in particular to cells served by various distributed units (DUs) that may be associated with a single centralized unit (CU). [Background technology]

[0002] The fifth generation (5G) of cellular systems is currently being standardized within the Third Generation Partnership Project (3GPP). 5G is being developed for maximum flexibility to support several substantially different use cases. These include enhanced mobile broadband (eMBB), machine type communications (MTC), ultra-reliable low latency communications (URLLC), sidelink device-to-device (D2D), and several other use cases.

[0003] FIG. 1 shows a high-level view of an exemplary 5G network architecture consisting of a Next Generation Radio Access Network (NG-RAN, 199) and a 5G Core (5GC, 198). The NG-RAN can include one or more gNBs connected to the 5GC via one or more NG interfaces, such as gNodeBs (gNBs) (100, 150) connected via respective interfaces (102, 152). More specifically, the gNBs can connect to one or more Access and Mobility Management Functions (AMFs) in the 5GC via respective NG-C interfaces and to one or more User Plane Functions (UPFs) in the 5GC via respective NG-U interfaces. The 5GC can include various other Network Functions (NFs), such as a Session Management Function (SMF).

[0004] Although not shown, in some deployments, 5GC can replace the evolved packet core (EPC) traditionally used with Long Term Evolution (LTE) evolved UMTS RAN (E-UTRAN). In such deployments, gNBs (e.g., 100, 150) can connect to one or more mobility management entities (MMEs) in the EPC 198 via respective S1-C interfaces. Similarly, gNBs can connect to one or more serving gateways (SGWs) in the EPC via respective NG-U interfaces.

[0005] Additionally, gNBs can be interconnected via one or more Xn interfaces, such as an Xn interface (140) between gNBs (100, 150). The radio technology for NG-RAN is often referred to as "New Radio" (NR). With respect to the NR interface to the UE, each gNB can support frequency division duplexing (FDD), time division duplexing (TDD), or a combination thereof. Each gNB can serve a geographic coverage area that includes one or more cells and, in some cases, can use different directional beams to provide coverage in each cell. Generally, a downlink "beam" is a coverage area of ​​a network transmitted reference signal (RS) that can be measured or monitored by a UE.

[0006] The NG-RAN is layered into the Radio Network Layer (RNL) and the Transport Network Layer (TNL). The NG-RAN architecture, i.e., the NG-RAN logical nodes and the interfaces between them, are specified as part of the RNL. For each NG-RAN interface (NG, Xn, F1), the associated TNL protocols and functions are specified. The TNL provides services for user plane transport and signaling transport.

[0007] The NG RAN logical node shown in FIG. 1 includes a central unit (CU or gNB-CU, e.g., 110) and one or more distributed units (DU or gNB-DU, e.g., 120, 130). The CU is a logical node that hosts upper layer protocols and performs various gNB functions, such as controlling the operation of the DU. The DU is a distributed logical node that hosts lower layer protocols and can include various subsets of gNB functions depending on the functional partitioning option. Thus, the CU and DU can each have various circuits required to perform their respective functions, including processing circuits, communication interface circuits (e.g., transceivers), and power circuits.

[0008] A gNB-CU connects to one or more gNB-DUs via respective F1 logical interfaces (e.g., 122 and 132 shown in FIG. 1). However, a gNB-DU can only connect to a single gNB-CU. A gNB-CU and its connected gNB-DUs only appear as a gNB to other gNBs and 5GCs. In other words, the F1 interface beyond the gNB-CU is not recognized (is invisible).

[0009] Figure 2 shows an example configuration of the NR user plane (UP) and control plane (CP) protocol stack between the UE (210), gNB (220), and AMF (230). The physical (PHY), medium access control (MAC), radio link control (RLC), and packet data convergence protocol (PDCP) layers between the UE and gNB are common to the uplink and CP. The PDCP layer provides encryption / decryption, integrity protection, sequence numbering, reordering, and duplicate detection for both the CP and UP. Additionally, PDCP provides header compression and retransmission for UP data.

[0010] On the UP side, Internet Protocol (IP) packets arrive at the PDCP layer as service data units (SDUs), which then create protocol data units (PDUs) for delivery to the RLC. The Service Data Adaptation Protocol (SDAP) layer handles quality of service (QoS), including mapping between QoS flows and data radio bearers (DRBs) and marking QoS flow identifiers (QFIs) in UL and DL packets. The RLC transfers PDCP PDUs to the MAC over logical channels (LCHs). The RLC provides error detection / correction, concatenation, segmentation / reassembly, sequence numbering, and reordering of data transferred to and from higher layers. The MAC provides mapping between LCHs and PHY transport channels, LCH prioritization, multiplexing to and demultiplexing from transport blocks (TBs), hybrid ARQ (HARQ) error correction, and dynamic scheduling (on the gNB side). The PHY provides transport channel services to the MAC and handles transmission over the NR air interface, e.g., via modulation, coding, antenna mapping, and beamforming.

[0011] On the CP side, the Non-Access Stratum (NAS) layer is located between the UE and the AMF and handles UE / gNB authentication, mobility management, and security control. The RRC is located below the NAS in the UE but terminates in the gNB rather than the AMF. The RRC controls communication between the UE and the gNB over the air interface, as well as UE mobility between cells within the NG-RAN. The RRC also broadcasts system information (SI) and performs the establishment, configuration, maintenance, and release of DRBs and signaling radio bearers (SRBs) used by the UE. Furthermore, the RRC controls the addition, modification, and release of carrier aggregation (CA) and dual connectivity (DC) configurations for the UE and performs various security functions such as key management.

[0012] After a UE is powered on, it remains in the RRC_IDLE state until an RRC connection is established with the network, at which point the UE transitions to the RRC_CONNECTED state (e.g., data transfer is possible). To transition from the RRC_IDLE state to the RRC_CONNECTED state, the UE must perform a random access (RA) procedure, in which the cell serving the UE is known and an RRC context is established for the UE at the serving gNB so that the UE and the gNB can communicate. The UE also sends an RRCSetupRequest message to the serving gNB as part of (or in conjunction with) the RA procedure.

[0013] Long Term Evolution (LTE) Release 10 introduced support for channel bandwidths wider than 20 MHz, which was carried over to NR. To maintain compatibility with legacy UEs from previous releases (e.g., Release 8), wideband LTE Release 10 carriers appeared as multiple component carriers (CCs), each with the structure of a Release 8 carrier. Release 10 UEs can receive multiple CCs based on carrier aggregation (CA). CCs can also be considered "cells," such that a UE performing CA has one primary cell (PCell) and one or more secondary cells (SCells), collectively referred to as a "cell group." NR also supports CA starting in Release 15.

[0014] As specified in 3GPP document RP-213565, Release 18 of NR includes work items on NR mobility enhancements, including the technical area of ​​L1 / L2-based inter-cell mobility. When a UE moves between the coverage areas of two cells, a serving cell change must be performed at some point. Currently, a serving cell change is triggered by Layer 3 (L3, e.g., RRC) measurements and includes RRC signaling for changing the PCell and PSCell (e.g., when dual connectivity is configured) and for releasing / adding an SCell (e.g., when CA is configured).

[0015] Currently, all inter-cell mobility involves a full Layer 2 (L2) and Layer 1 (L1, i.e., PHY) reset, resulting in longer latency, increased signaling overhead, and longer disruptions than with intra-cell beam switching. Therefore, the goal of the L1 / L2 mobility enhancements in Release 18 is to facilitate serving cell change via L1 / L2 signaling to address these issues and / or difficulties. Summary of the Invention

[0016] These Release 18 L1 / L2 mobility enhancements must also take into account the CU / DU split architecture shown in Figure 1 and described above, including intra-DU (within a DU) and inter-DU (between DUs) / intra-CU (within a CU) cell changes, where the source and target cells of a UE are served by different source and target DUs associated with a single CU. However, various issues, challenges, and / or difficulties exist.

[0017] For example, since one of the goals in L1 / L2 inter-cell mobility is to reduce the interruption time for UE data transmission, the UE needs to be ready to communicate with the target cell upon (or shortly thereafter) receiving L1 / L2 signaling for mobility execution from the source cell. As a more specific example, the UE must be able to transmit uplink (UL) data or scheduling requests (SRs) to the target cell and / or monitor downlink (DL) control channels (e.g., PDCCH) from the target cell. However, currently, the UE does not have the necessary information about the target cell configuration (e.g., TCI state) to initiate communication in a manner that significantly reduces the interruption time.

[0018] An objective of embodiments of the present disclosure is to address these and related issues, problems, and / or difficulties, thereby facilitating L1 / L2 mobility of UEs between cells within a RAN (e.g., NG-RAN).

[0019] Some embodiments of the present disclosure include a method (e.g., a procedure) for a UE configured to communicate with a RAN node that includes a CU and a DU that provides a serving cell for the UE.

[0020] The example methods include receiving a lower layer signaling message from a DU indicating that the UE should perform L1 / L2-based inter-cell mobility to a first candidate cell served by the candidate DU. The lower layer signaling message includes an indicator or identity of the first candidate cell and an indication of a first TCI state to be used by the UE to communicate with the first candidate cell. The example methods further include performing an L1 / L2 mobility procedure toward the first candidate cell and communicating in the first candidate cell based on the first TCI state.

[0021] In some embodiments, the indication of the first TCI state is a TCI state identifier, while in other embodiments, the indication of the first TCI state is an index of a first beam or reference signal (RS) transmitted in the first candidate cell.

[0022] In some of these embodiments, these example methods also include receiving, from the CU via the DU, an RRCReconfiguration message including configurations associated with one or more candidate cells for L1 / L2-based inter-cell mobility, including the first candidate cell. Each candidate cell configuration includes multiple TCI state configurations, each TCI state configuration including an index of a beam or RS configured as a quasi-co-located (QCL) source. In such embodiments, these example methods further include selecting, as the first TCI state, one of the TCI state configurations including the index of the first beam or RS as a QCL source.

[0023] Another embodiment includes a method (e.g., a procedure) for a DU of a RAN node, coupled to a CU of the RAN node, and configured to provide a serving cell for a UE.

[0024] The example methods include selecting a first candidate cell provided by a candidate DU for L1 / L2-based inter-cell mobility of a UE served by the DU via a serving cell. The example methods further include transmitting a lower layer signaling message to the UE indicating that the UE should perform L1 / L2-based inter-cell mobility to the first candidate cell. The lower layer signaling message includes an indicator or identity of the first candidate cell and an indication of a first TCI state to be used by the UE to communicate with the first candidate cell.

[0025] In some embodiments, these example methods may also include receiving from the UE results of measurements performed by the UE on multiple beams or RSs transmitted in the first candidate cell. The measurement results include respective indices of the multiple beams or RSs. In some of these embodiments, the multiple beams or RSs include one or more of an SSB and a CSI-RS. In some of these embodiments, the first TCI state is associated with the first beam or RS having the most favorable measurement results (e.g., highest SS-RSRP) for L1 / L2 mobility to the first candidate cell.

[0026] In some embodiments, the indication of the first TCI state is an index of the first beam or RS. In others of these embodiments, the indication of the first TCI state is a TCI state identifier. In some embodiments, the candidate DU is associated with a CU and / or is part of a RAN node.

[0027] Another embodiment includes a method (eg, procedure) for a candidate DU configured to communicate with a CU of a RAN node.

[0028] These example methods include receiving a request from a DU serving the UE via a serving cell or from a CU to configure the UE with at least one candidate cell for L1 / L2-based inter-cell mobility. These example methods further include transmitting, to the CU or DU, configurations for one or more candidate cells provided by the candidate DU, including a first candidate cell. These example methods further include receiving, by the UE, a message from the DU indicating an L1 / L2 mobility procedure. The message includes an indicator or identity of the first candidate cell for the UE's L1 / L2-based inter-cell mobility and an indication of a first TCI state to be used by the UE to communicate with the first candidate cell. These example methods further include communicating with the UE at the first candidate cell based on the first TCI state.

[0029] In some embodiments, the candidate DU is associated with a CU and / or is part of a RAN node. In some embodiments, the indicator or identity of the first candidate cell and the indication of the first TCI state are received in a copy or encapsulated in a lower layer signaling message sent by the DU to the UE.

[0030] In some embodiments, the indication of the first TCI state is an index of a first beam or RS transmitted in the candidate cell. In such embodiments, these example methods may further include determining the first TCI state or an identifier thereof based on the index of the first beam or RS and a mapping between a TCI state identifier used in the first candidate cell and an index of the beam or RS transmitted in the first candidate cell. In other embodiments, the indication of the first TCI state is a TCI state identifier.

[0031] Other embodiments have a UE and a DU configured to perform operations corresponding to any of the example methods described herein. Other embodiments further include a non-transitory computer-readable medium storing computer-executable instructions that, when executed by a processing circuit, configure the UE and the DU to perform operations corresponding to any of the example methods described herein.

[0032] These and other embodiments described herein can facilitate faster execution of L1 / L2 inter-cell mobility than existing L3-based inter-cell mobility because the execution phase is separated from the preparation phase, and therefore the timing of the lower layer signaling that triggers execution of L1 / L2 inter-cell mobility is at the discretion of the serving DU. These advantages are made possible by providing the UE with a TCI state ID or SSB index for a candidate cell in the lower layer signaling that triggers execution of L1 / L2 inter-cell mobility, thereby facilitating timely UE communication with the candidate cell. Furthermore, by providing the UE with an indication of whether to perform a MAC reset in conjunction with L1 / L2 inter-cell mobility, embodiments avoid data loss and excessive interruptions when a MAC reset is unnecessary. Broadly speaking, embodiments improve UE mobility in the RAN.

[0033] These and other objects, features, and advantages of the present disclosure will become apparent from a reading of the following detailed description in light of the drawings briefly described below. [Brief explanation of the drawings]

[0034] [Figure 1] shows a high-level view of an exemplary 5G network architecture. [Figure 2] shows an exemplary configuration of the NR UP and CP protocol stack. [Figure 3] , and [Figure 4] shows a logical architecture for a gNB arranged in the CU / DU split architecture shown in FIG. [Figure 5] 1 shows a signaling flow for an inter-DU / intra-CU mobility procedure for a UE. [Figure 6A] , [Figure 6B] , [Figure 6C] , [Figure 6D] , [Figure 6E] , and [Figure 6F] 1A-1B illustrate various ASN.1 data structures for configuring L1 / L2 inter-cell mobility candidates in a UE, according to various embodiments of the present disclosure. [Figure 7] , [Figure 8] , [Figure 9] , and [Figure 10] 1 illustrates a signaling diagram of a procedure for configuring a UE for inter-DU L1 / L2 inter-cell mobility from a serving DU to a candidate DU associated with the same CU, according to various embodiments of the present disclosure. [Figure 11] 1 illustrates an example method (e.g., procedure) for a UE, in accordance with various embodiments of the present disclosure. [Figure 12] 1 illustrates an example method (e.g., procedure) for serving DUs, according to various embodiments of the present disclosure. [Figure 13] 1 illustrates an exemplary method (e.g., procedure) for a candidate DU, according to various embodiments of the present disclosure. [Figure 14] 1 illustrates a communication system according to various embodiments of the present disclosure. [Figure 15] 1 illustrates a UE according to various embodiments of the present disclosure. [Figure 16] 1 illustrates a network node according to various embodiments of the present disclosure. [Figure 17] 1 illustrates a host computing system according to various embodiments of the present disclosure. [Figure 18] 1 is a block diagram of a virtualization environment in which functionality implemented by some embodiments of the present disclosure may be virtualized. [Figure 19] 1 illustrates communication between a host computing system, a network node, and a UE over multiple connections (at least one of which is wireless) in accordance with various embodiments of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0035] The embodiments briefly summarized above will now be described in more detail with reference to the accompanying drawings. These descriptions are provided as examples to explain the subject matter to those skilled in the art and should not be construed as limiting the scope of the subject matter to only the embodiments described herein. More specifically, examples illustrating the operation of various embodiments according to the advantages described above are provided below.

[0036] In general, all terms used herein should be interpreted according to their ordinary meaning to those of ordinary skill in the relevant art, unless a different meaning is expressly defined and / or implied from the context of use. All references to elements, devices, components, means, steps, etc. should be interpreted openly as referring to at least one instance of the element, device, component, means, step, etc., unless expressly stated otherwise or clearly implied from the context of use. The acts of any method and / or procedure disclosed herein need not be performed in the exact order disclosed, unless an act is explicitly described after or before another act and / or unless it is implicit that an act must follow or precede another act. Any feature of any embodiment disclosed herein may be applied to any other disclosed embodiment, as appropriate. Similarly, any advantage of any embodiment described herein may be applied to any other disclosed embodiment, as appropriate.

[0037] Furthermore, the following terminology is used in the following description:

[0038] Radio Access Node: As used herein, a "radio access node" (or equivalently, "radio network node," "radio access network node," or "RAN node") may be any node in a radio access network (RAN) that operates to transmit and / or receive signals wirelessly. Some examples of radio access nodes include, but are not limited to, base stations (e.g., gNB in ​​a 3GPP 5G / NR network or enhanced or eNB in ​​a 3GPP LTE network), base station distribution components (e.g., CU and DU), high-power or macro base stations, low-power base stations (e.g., micro, pico, femto, or home base stations), integrated access backhaul (IAB) nodes, transmission points (TP), transmit / receive points (TRP), remote radio units (RRUs or RRHs), and relay nodes.

[0039] Core network node: As used herein, a "core network node" is any type of node in a core network. Some examples of core network nodes include, for example, a Mobility Management Entity (MME), a Serving Gateway (SGW), a PDN Gateway (P-GW), a Policy and Charging Rules Function (PCRF), an Access and Mobility Management Function (AMF), a Session Management Function (SMF), a User Plane Function (UPF), a Charging Function (CHF), a Policy Control Function (PCF), an Authentication Server Function (AUSF), a Location Management Function (LMF), or others.

[0040] Wireless Device: As used herein, a "wireless device" (or "WD" for short) is any type of device that is capable of, configured, arranged, and / or operable to communicate wirelessly with network nodes and / or other wireless devices. Communicating wirelessly may include transmitting and / or receiving wireless signals using electromagnetic waves, radio waves, infrared, and / or other types of signals suitable for conveying information through the air. Unless otherwise specified, the term "wireless device" is used interchangeably herein with the term "user equipment" (or "UE" for short), and both of these terms include different meanings than the term "network node."

[0041] Wireless node: As used herein, a "wireless node" may be either a "wireless access node" (or equivalent terms) or a "wireless device."

[0042] Network Node: As used herein, a "network node" is any node that is part of either the radio access network (e.g., radio access node or equivalent term) or core network (e.g., core network node as discussed above) of a cellular communications network. Functionally, a network node is equipment that is configured, arranged, and / or operable to communicate, directly or indirectly, with wireless devices and / or other network nodes or equipment in the cellular communications network to enable and / or provide wireless access to wireless devices and / or perform other functions (e.g., management) in the cellular communications network.

[0043] Node: As used herein, the term "node" (without any prefix) may be any type of node that may be in or with a wireless network (including a RAN and / or core network), including a radio access node (or equivalent term), a core network node, or a wireless device. However, the term "node" may be limited to a particular type (e.g., radio access node, IAB node) based on its unique characteristics in any given context.

[0044] The above definitions are not meant to be exclusive. In other words, various of the above terms may be explained and / or described elsewhere in this disclosure using the same or similar terms. Nevertheless, to the extent that such other explanations and / or descriptions contradict the above definitions, the above definitions shall prevail.

[0045] It should be noted that the description herein focuses on 3GPP cellular communication systems, and therefore, 3GPP terminology or terms similar to 3GPP terminology are generally used. However, the concepts disclosed herein are not limited to 3GPP systems. Other wireless systems, including, but not limited to, Wideband Code Division Multiple Access (WCDMA), Worldwide Interoperability for Microwave Access (WiMax), Ultra Mobile Broadband (UMB), and Global System for Mobile Communications (GSM), may also benefit from the concepts, principles, and / or embodiments described herein. Furthermore, although the term "cell" is used herein, it should be understood that a beam can be used instead of a cell (particularly with respect to 5G NR), and thus the concepts described herein apply equally to both cells and beams.

[0046] Figure 3 shows the logical architecture of a gNB deployed in a CU / DU split architecture, such as the gNB (100) of Figure 1. This logical architecture separates the CU into CP and UP functions, referred to as CU-C and CU-U, respectively. Furthermore, each of the NG, Xn, and F1 interfaces is split into a CP interface (e.g., NG-C) and a UP interface (e.g., NG-U). Note that the terms "central entity" and "distributed entity" in Figure 3 refer to physical network nodes.

[0047] Figure 4 shows another example gNB logical architecture including two gNB-DUs, a gNB-CU-CP, and multiple gNB-CU-UPs. The gNB-CU-CP may be connected to the gNB-DU via an F1-C interface, and the gNB-CU-UP may be connected to the gNB-DU via an F1-U interface and to the gNB-CU-CP via an E1 interface. Each gNB-DU may be connected to only one gNB-CU-CP, and each gNB-CU-UP may be connected to only one gNB-CU-CP. One gNB-DU may be connected to multiple gNB-CU-UPs under the control of the same gNB-CU-CP. Also, one gNB-CU-UP may be connected to multiple DUs under the control of the same gNB-CU-CP. When referring to an operation performed by a "CU" herein, it should be understood that this operation may be performed by any entity within the CU (e.g., CU-CP, gNB-CU-CP) unless otherwise specified.

[0048] When a UE moves between the coverage areas of two cells, at some point a serving cell change needs to be performed. Currently, a serving cell change is triggered by Layer 3 (L3, e.g., RRC) measurements and involves RRC signaling to change the PCell and PSCell (e.g., if dual connectivity is configured) and RRC signaling to release / add an SCell (e.g., if CA is configured). Currently, all inter-cell mobility involves a full Layer 2 (L2) and Layer 1 (L1, i.e., PHY) reset. This includes inter-DU / intra-CU cell changes, where the UE's source and target cells are served by different source and target DUs associated with a single CU.

[0049] Figure 5 illustrates a signaling flow for an inter-DU / intra-CU mobility procedure for a UE (510), where a source DU (520) and a target DU (530) are associated with the same CU (540), i.e., part of a single RAN node (550), such as a gNB. Although the operations shown in Figure 5 are labeled with reference numbers, this is done for ease of explanation and does not require or imply any order of operations, unless otherwise specified.

[0050] In action 1, the UE sends a MeasurementReport message to the source DU. In action 2, the source DU sends a UL RRC MESSAGE TRANSFER message to the CU to convey the received MeasurementReport message. In action 2a (which is optional), the CU may send a UE CONTEXT MODIFICATION REQUEST message to the source DU to inquire about the latest configuration. In action 2b, the source DU responds with a UE CONTEXT MODIFICATION RESPONSE message containing all configuration information.

[0051] In operation 3, a UE CONTEXT SETUP REQUEST message is sent to the target DU to create a UE context and set up one or more data bearers. The UE CONTEXT SETUP REQUEST message contains Handover Preparation Information. In operation 4, the target DU responds to the CU with a UE CONTEXT SETUP RESPONSE message.

[0052] In operation 5, the CU sends a UE CONTEXT MODIFICATION REQUEST message to the source DU, including the generated RRCReconfiguration message and indicating to stop data transmission for the UE. The source DU further sends a Downlink Data Delivery Status frame to inform the CU about the downlink data that failed to be transmitted to the UE. In operation 6, the source DU forwards the received RRCReconfiguration message to the UE. In operation 7, the source DU responds to the CU with a UE CONTEXT MODIFICATION RESPONSE message.

[0053] In operation 8, the UE performs a random access procedure with the target DU. The target DU notifies the CU by sending a Downlink Data Delivery Status frame. Downlink packets, which may include PDCP PDUs that were not successfully transmitted in the source DU, are sent from the CU to the target DU. It is up to the CU's implementation whether to start transmitting DL User Data to the DU before or after receiving the Downlink Data Delivery Status.

[0054] In operation 9, the UE responds to the target DU with an RRCReconfigurationComplete message. In operation 10, the target DU sends a UL RRC MESSAGE TRANSFER message to the CU to convey the received RRCReconfigurationComplete message. Downlink packets are sent to the UE, and uplink packets are sent from the UE and forwarded to the CU via the target DU. In operation 11, the CU sends a UE CONTEXT RELEASE COMMAND message to the source DU. In operation 12, the source DU releases the UE context.

[0055] As briefly mentioned above, Release 18 of NR includes work items on NR mobility enhancements, including the technical area of ​​L1 / L2-based inter-cell mobility. The goal of L1 / L2 mobility enhancements in Release 18 is to facilitate serving cell changes via L1 / L2 signaling instead of L3 (e.g., RRC) signaling. One area of ​​interest is inter-DU / intra-CU cell changes, as shown in Figure 5 above. From the UE's perspective, the procedure shown in Figure 5 may result in longer latency, increased signaling overhead, and longer interruptions than with intra-cell beam switching.

[0056] Therefore, a broad goal of the L1 / L2 mobility enhancements in Release 18 is to facilitate serving cell change via L1 / L2 signaling to address these issues and / or difficulties. Some further specific goals include: Configuration and maintenance for multiple candidate cells, allowing fast application of settings for candidate cells Dynamic switching mechanism between candidate serving cells (including SpCell and SCell) for potentially applicable scenarios based on L1 / L2 signaling L1 enhancements for inter-cell beam management, including L1 measurement and reporting and beam indication ● Timing advance management, and • CU-DU interface signaling to support L1 / L2 mobility, if required. These Release 18 L1 / L2 mobility enhancements must also take into account the CU / DU split architecture shown in Figures 1 and 3-4, including intra-DU and inter-DU / intra-CU cell changes. In inter-DU / intra-CU scenarios, candidate cells for L1 / L2 inter-cell mobility are cells served by neighboring DUs to the DU currently serving (serving or source) the UE's PCell (or PSCell for SCG change during DC).

[0057] As shown in Figure 5, the execution of L3 mobility is triggered by the source DU sending to the UE an RRCReconfiguration message (operation 6) generated by the CU and received from the CU during the preparation phase. This message is based on the CU requesting the target DU to set up a UE context and provide the CU with a target cell configuration (e.g., CellGroupConfig). Thus, when the target DU receives a UE CONTEXT SETUP REQUEST (operation 3), the target DU knows that the UE will arrive in the target cell immediately after receiving the RRCReconfiguration from the CU via the source DU, and the target cell resources reserved for the incoming UE will be used immediately.

[0058] Since one of the goals in L1 / L2 inter-cell mobility is to reduce the interruption time for UE data transmission, the UE needs to be ready to communicate with the target cell upon (or shortly thereafter) receiving L1 / L2 signaling for mobility execution from the source cell. For example, the UE must be able to transmit UL data or a scheduling request (SR) to the target cell and / or monitor a DL control channel (e.g., PDCCH) from the target cell. In other words, the UE needs to know the target cell to which the UE is moving so that it can apply the corresponding configuration, including the correct transmission configuration indicator (TCI) state for that cell. Similarly, when the source DU sends L1 / L2 signaling for mobility execution, the target DU needs to be ready to schedule UL and DL transmissions for the UE in the target cell and receive a scheduling request (SR) from the UE.

[0059] Each TCI state includes parameters for setting a quasi-co-location (QCL) relationship between one or more source DL reference signals (RSs, e.g., SSBs) and one or more other DL RSs, such as a physical DL shared channel (PDSCH) or physical DL control channel (PDCCH) of a DL CSI-RS resource or a DM-RS port of a channel state information RS (CSI-RS) port. In general, different DL RSs may have a QCL relationship if the respective antenna ports in a base station transmitter satisfy the condition that the characteristics of the channel on which symbols on one antenna port are carried can be inferred from the channel on which symbols on the other antenna port are carried.

[0060] However, currently, the UE does not have the necessary information about the target cell configuration (eg, TCI state) to initiate communication in a manner that significantly reduces interruption time.

[0061] Embodiments of the present disclosure address these and other challenges, difficulties, and / or problems by providing a flexible and efficient signaling technique in which a UE receives lower layer signaling from a source DU serving the UE's source cell to initiate L1 / L2 inter-cell mobility execution for a target candidate cell configured for the UE, the lower layer signaling including information about the TCI state of the target candidate cell, the target cell being served by a target DU associated with the same CU as the source DU.

[0062] In some embodiments, the information is a TCI state identifier (ID) from which the UE can directly determine the TCI state setting of the target candidate cell to use during L1 / L2 inter-cell mobility. In this case, the source DU has a mapping between TCI state IDs and SSB indices for the target cell (e.g., provided via the CU by the target DU serving the target cell) and receives a measurement report from the UE that includes the SSB index of the target cell. Based on this information, the source DU can select an SSB index for the target cell, determine the corresponding TCI state ID, and provide this information to the UE in lower layer signaling.

[0063] In another embodiment, the information is an SSB index that identifies the source RS (i.e., SSB) as the QCL source for the TCI state. The UE selects the TCI state of the target cell to use during L1 / L2 inter-cell mobility based on the target cell configuration and the SSB index. In particular, the UE selects a TCI state configuration that includes configuring the indicated SSB index as the QCL source.

[0064] In some embodiments, the lower layer signaling may also include an indication of whether the UE should perform a MAC reset when performing an L1 / L2 inter-cell mobility procedure.

[0065] Embodiments may provide various benefits and / or advantages. For example, embodiments may facilitate much faster execution of L1 / L2 inter-cell mobility than existing L3-based inter-cell mobility because the execution phase is separated from the preparation phase, and as a result, the timing of the lower layer signaling that triggers execution of L1 / L2 inter-cell mobility is at the discretion of the source DU. These advantages are made possible by providing the UE with a TCI state ID or SSB index for a candidate cell in the lower layer signaling that triggers execution of L1 / L2 inter-cell mobility, which facilitates timely UE communication with the candidate cell. Furthermore, by providing the UE with an indication of whether the UE should perform a MAC reset in conjunction with the L1 / L2 inter-cell mobility procedure, embodiments may avoid data loss and excessive interruptions in cases where a MAC reset is unnecessary. Broadly speaking, embodiments improve mobility in a RAN (e.g., NG-RAN).

[0066] In this disclosure, the terms "L1 / L2-based inter-cell mobility" (as used in 3GPP work items), "L1 / L2 mobility," "L1-mobility," "L1-based mobility," "L1 / L2-centric inter-cell mobility," "L1 / L2 inter-cell mobility," "inter-cell beam management," and "inter-DU L1 / L2-based inter-cell mobility" may be used interchangeably. These terms refer to a scenario in which a UE receives lower layer (i.e., lower than RRC, such as MAC or PHY) signaling from the network indicating the UE changing its serving cell (e.g., PCell) from a source cell to a target cell. Exemplary lower layer signaling includes L1 DL control information (DCI) and L2 MAC control element (CE). Compared to traditional RRC signaling, lower layer signaling can reduce processing time and interruption time during mobility and increase mobility robustness because the network can respond more quickly to changes in the UE's channel conditions.

[0067] In this disclosure, the following terms may be used interchangeably with respect to L1 / L2 inter-cell mobility: "neighbor DU," "non-serving DU," "candidate DU," and "target DU." Similarly, the following terms may be used interchangeably with respect to L1 / L2 inter-cell mobility: "serving DU" and "source DU."

[0068] Another relevant aspect in L1 / L2 inter-cell mobility is that a cell may be associated with multiple SSBs (or beams), i.e., different SSBs are transmitted in different spatial directions during a half-frame, thereby increasing the coverage area of ​​the cell. A cell may further be associated with multiple CSI-RS resources, which may be transmitted in different spatial directions. Thus, in L1 / L2 inter-cell mobility, receiving lower layer signaling indicating that a UE should change from one beam in its serving cell to another beam in a (candidate) neighboring cell also involves changing the serving cell.

[0069] The following description refers to the configuration of L1 / L2-based inter-cell mobility candidate cells (also referred to as "candidate cell configurations") that are generated by a candidate DU and encapsulated in an RRCReconfiguration message received by a UE when configured for inter-DU L1 / L2 inter-cell mobility. The RRCReconfiguration message may include one or more of these configurations for each of one or more candidate cells served by the candidate DU. Each configuration includes parameters and / or settings required for the UE to operate in the corresponding candidate cell, which now becomes the target cell for mobility, upon receiving lower layer signaling indicating L1 / L2-based inter-cell mobility to the corresponding candidate cell.

[0070] The configuration of the L1 / L2-based inter-cell mobility candidate cell may include parameters of the serving cell(s) with one or more of a group of parameters in an SpCellConfig information element (IE) (or SCellConfig IE in case of an SCell). These parameters may include any of the following:

[0071] A cell index (e.g., encoding fewer bits than the cell identifier of the L1 / L2 inter-cell mobility candidate cell). This could be the 'servCellIndex' or 'candidateCellIndex' fields of the 'ServCellIndex' or 'CandidateCellIndex' IEs. After this is set, the index may be used later in lower layer signaling to indicate to the UE that this is a candidate cell to which the UE needs to move, in the L1 / L2 inter-cell mobility procedure, and / or in RRC messages indicating some action on that particular candidate cell.

[0072] UE (e.g., UE-specific or UE-dedicated) cell configuration corresponding to the configuration of a candidate cell for L1 / L2-based inter-cell mobility, with parameters possibly adjusted for the UE according to the UE capabilities. The UE cell configuration may include parameters defined in an IE called ServingCellConfig (defined in 3GPP TS38.331), such as DL and UL frequency configuration (including bandwidth parts), L1 control channels (PDCCH, CORESET, PUCCH, etc.), L1 data channels (PDSCH, PUSCH, etc.), etc.

[0073] A common cell configuration corresponding to the configuration of candidate cells for L1 / L2-based inter-cell mobility in the ServingCellConfigCommon element, which may be provided in the ReconfigurationWithSync element or separately. This common cell configuration includes, for example, the RA configuration of the UE to access the candidate cells as needed.

[0074] • Radio link fault settings such as timer T310, counter N310, counter N311, and timer N311 values.

[0075] • At least one UE identifier for identifying the UE within a candidate cell for L1 / L2-based inter-cell mobility, such as a Cell Radio Network Temporary Identifier (C-RNTI).

[0076] In some embodiments, when a UE is configured with multiple L1 / L2 inter-cell mobility candidate cells provided by a neighboring DU, the neighboring DU generates and sends to the CU multiple sets of parameters in multiple SpCellConfig IEs. For example, the UE may receive a list of SpCellConfig IEs, one for each L1 / L2 inter-cell mobility candidate cell.

[0077] In some embodiments, the configuration of candidate cells for L1 / L2-based inter-cell mobility of a neighboring DU may be an SpCell configuration provided as part of a cell group configuration (e.g., a PCell for an MCG) and may also include one or more SCell configurations and cell group-specific configurations (e.g., cell group identity, cell group PHY configuration, cell group MAC configuration, concurrent TCI state configuration for the cell group, etc.). In these embodiments, the UE is configured with a cell group configuration for each neighboring DU candidate cell. One alternative is for the UE to receive one configuration per cell group, where the configuration of candidate cells for L1 / L2-based inter-cell mobility is an SpCell candidate configuration within that group. Lower layer signaling then indicates to the UE to change to the configured cell group candidate, e.g., from MCG configuration A to MCG configuration B.

[0078] In some embodiments, when a UE is configured with multiple L1 / L2 inter-cell mobility candidates, the neighboring DU generates and sends multiple cell group configurations to the CU, each of which is associated with a different candidate. For example, the neighboring DU may generate and send a list of IEs called CellGroupConfig.

[0079] In some embodiments, the L1 / L2 inter-cell mobility candidate may be within the same frequency as the current PCell or within a different frequency. In some embodiments, the L1 / L2 inter-cell mobility candidate may be an SCell candidate.

[0080] The implementation of RRC signaling for the configuration of L1 / L2-based inter-cell mobility candidate cells can be done in different ways corresponding to various embodiments. Some examples are given below.

[0081] Some embodiments may utilize one RRC Reconfiguration message per candidate cell. In this case, the UE receives (a list of) multiple RRC Reconfiguration messages within a single RRC Reconfiguration message, as shown in FIG. 6A. Each RRC Reconfiguration message identifies and / or contains the configuration of an L1 / L2-based inter-cell mobility candidate cell that is stored by the UE and will be applied / used / activated upon receiving lower layer signaling for the corresponding L1 / L2 inter-cell mobility procedure to that candidate cell. This model allows full flexibility for the target node to modify / release / keep any parameters / fields in an existing RRC Reconfiguration message (e.g., measurement configuration, bearers, etc.), as in L3 reconfiguration.

[0082] As an example of these embodiments, the neighboring DU generates a CellGroupConfig IE for each candidate (including candidate SpCells and SCells, if applicable), and the CU generates an RRCReconfiguration message for each candidate based on the respective CellGroupConfig IE, which are received by the UE and stored to be applied if / when the UE later receives an L1 / L2 inter-cell mobility command (e.g., MAC CE) indicating a particular one of the candidate cells.

[0083] Other embodiments may utilize one CellGroupConfig IE per candidate cell. In this model, the UE receives a list of CellGroupConfig IEs in the RRCReconfiguration message, each specifying and / or including the configuration of an L1 / L2-based inter-cell mobility candidate cell. Figure 6B shows an example of these embodiments. Each CellGroupConfig IE is stored by the UE and applied / used / activated upon receiving lower layer signaling for the corresponding L1 / L2 inter-cell mobility procedure to that candidate cell. This model allows neighboring DUs to modify / release / retain any parameters / fields that are part of the CellGroupConfig IE without changing the rest of the RRCReconfiguration message (in which the CellGroupConfig IE is received by the UE). This means that measurement configuration, bearers, security, etc. remain the same and are not changed by the target node.

[0084] As an example of these embodiments, the neighboring DU generates a CellGroupConfig IE for each target candidate (including associated candidate SpCells and SCells), and the CU generates an RRCReconfiguration message with a list of such CellGroupConfig IEs, which are received by the UE and stored to be applied if / when the UE later receives an L1 / L2 inter-cell mobility command (e.g., MAC CE) indicating a particular one of the candidate cells.

[0085] Other embodiments may provide the UE with multiple (K) SpCellConfig IEs and / or multiple (K) ServingCellConfigCommon IEs included in the configuration of the L1 / L2-based inter-cell mobility candidate cell. This solution provides minimal flexibility to neighboring DUs when generating the K SpCellConfig IEs and / or K ServingCellConfigCommon IEs provided to the UE, since only cell-specific parameters (e.g., bandwidth part, DL / UL configuration) can be modified / released / retained by the neighboring DU. Figures 6C-E show examples of these embodiments.

[0086] Other embodiments may provide the UE with multiple (K) physical cell identities (PCIs) within the same PCell. Figure 6F shows examples of these embodiments. In this model, multiple PCIs are configured for the same TCI state configuration, where each PCI specifies a configuration of an L1 / L2-based inter-cell mobility candidate cell. This approach does not offer any flexibility, as all parameters / fields used to configure the configuration of an L1 / L2-based inter-cell mobility candidate cell are fixed, and only changes to the PCI, scrambling Id, and / or C-RNTI are allowed for neighboring DUs.

[0087] In various embodiments, the UE receives at least one configuration for an L1 / L2-based inter-cell mobility candidate cell (or candidate cell configuration) via higher layer (e.g., RRC) signaling. The candidate cell configuration may be (or may be included in) a cell group configuration (e.g., in an IE named CellGroupConfig) or a serving cell configuration (e.g., in IEs named ServingCellConfig and / or ServingCellConfigCommon) of the candidate cell for L1 / L2 inter-cell mobility. The UE may have received multiple configurations for the L1 / L2-based inter-cell mobility candidate cell, possibly from multiple candidate DUs serving the respective candidate cells. In some cases, the serving DU may also be a candidate DU, but the candidate cell provided by the serving DU is a cell other than the serving cell of the UE.

[0088] In some embodiments, a serving (or source) DU decides to trigger L1 / L2 inter-cell mobility for the UE to one of the candidate cells previously configured for the UE's L1 / L2 inter-cell mobility. The serving DU's decision may be based on one or more reports received from the UE, such as a CSI report, a measurement report, etc. Such reports may include UE measurement information regarding one or more of the configured candidate cells.

[0089] In some embodiments, the measurement information for the L1 / L2 inter-cell mobility candidate cell may include Synchronization Signal (SS) Reference Signal Received Power (SS-RSRP) measurements for at least one configured / indicated SSB of the L1 / L2 inter-cell mobility candidate cell, where the SS-RSRP is measured only in RSs having SSBs with the same SSB index and the same physical cell identity (PCI) as those of the L1 / L2 inter-cell mobility candidate cell.

[0090] In some embodiments, the SS-RSRP may be derived as a linear average over the power contributions ([W]) of resource elements carrying the secondary synchronization signal (SSS) of the L1 / L2 inter-cell candidate cell. In some embodiments, the SS-RSRP determination may be further based on the demodulation reference signal (DMRS) for the physical broadcast channel (PBCH) of the L1 / L2 inter-cell candidate cell and (if indicated by higher layers) the CSI-RS of the L1 / L2 inter-cell candidate cell.

[0091] In one embodiment, the SS-RSRP indicates a specific SSB for performing the SS-RSRP measurement, and then the SS-RSRP is measured only from the indicated set of SS / PBCH blocks. In some embodiments, the SS-RSRP is used so that the L1-RSRP is included in the CSI report.

[0092] In some embodiments, the measurement information for the L1 / L2 inter-cell mobility candidate cell may include one of the following: Measurement results of SS Reference Signal Received Quality (SS-RSRQ) for at least one configured / indicated SSB of a candidate cell for L1 / L2 inter-cell mobility Measurement results of SS signal-to-noise and interference ratio (SS-SINR) for at least one configured / instructed SSB of a L1 / L2 inter-cell mobility candidate cell ● Measurement results of CSI-RS received power (CSI-RSRP) for at least one configured / indicated CSI-RS resource of an L1 / L2 inter-cell mobility candidate cell. In some embodiments, the CSI-RSRP measurement result is a linear average over the power contributions (in [W]) of the resource elements of the antenna ports carrying the CSI-RS configured for RSRP measurement within the considered measurement frequency bandwidth on the configured CSI-RS occasion.

[0093] Measurement results of CSI-RS received quality (CSI-RSRQ) for at least one configured / indicated CSI-RS resource of a L1 / L2 inter-cell mobility candidate cell CSI-RS signal-to-noise and interference ratio (CSI-SINR) measurement results for at least one configured / indicated CSI-RS resource of the L1 / L2 inter-cell mobility candidate cell L1 / L2 inter-cell mobility L1 reference signal received power (L1-RSRP) based on at least one SSB of a candidate cell L1 reference signal received power (L1-RSRP) based on at least one CSI-RS resource of a candidate cell for L1 / L2 inter-cell mobility Layer 1 SINR (L1-SINR) based on at least one SSB of a candidate cell for L1 / L2 inter-cell mobility Layer 1 SINR (L1-SINR) based on at least one CSI-RS resource of a candidate cell for L1 / L2 inter-cell mobility Channel Quality Indicator (CQI) based on SSB and / or CSI-RS in CSI resource configuration Precoding matrix indicator (PMI) based on SSB and / or CSI-RS in CSI resource configuration CSI-RS Resource Indicator (CRI) based on SSB and / or CSI-RS in CSI resource configuration SS / PBCH Block Resource Indicator (SSBRI) based on SSB and / or CSI-RS in CSI resource configuration Layer Indicator (LI) based on SSB and / or CSI-RS in CSI resource configuration ●Rank indicator (RI) based on SSB and / or CSI-RS in CSI resource configuration.

[0094] In some embodiments, the serving DU generates and sends lower layer signaling (e.g., MAC CE, DCI, etc.) to the UE indicating that the UE should perform L1 / L2 inter-cell mobility to the target cell. The lower layer signaling may include one or more of the following indications: Candidate cells that are targets for UE to perform L1 / L2 inter-cell mobility • The TCI states of the candidate cells that the UE considers should be activated in the candidate cells for the UE's L1 / L2 inter-cell mobility.

[0095] In some embodiments, the indicated candidate cell is a configured candidate cell for which the UE has provided measurement reports to the serving DU, which may be, for example, one of the candidate cells that the UE has indicated as having the highest RSRP, RSRQ, and / or SINR.

[0096] In some embodiments, the candidate cell indication may be an identifier having N1 (an integer) bits, which is mapped to a cell identifier of the target candidate cell having N2 (>N1) bits. For example, a candidate cell configuration (e.g., previously received via RRC) may include an N1 bit identifier, and thus, when a UE receives lower layer signaling including an N1 bit identifier, it can match the corresponding candidate cell configuration.

[0097] In some embodiments, the indication of the TCI state is a TCI state identifier (ID), from which the UE can directly determine the TCI state settings of candidate cells to use during L1 / L2 inter-cell mobility.

[0098] For example, the indicated TCI state may be the TCI state corresponding to the SSB index for which the UE has reported the strongest measurement (e.g., SSB RSRP, SSB SINR, SSB RSRQ) for the candidate cell. This SSB index is set as the QCL source for the indicated TCI state. In other words, the serving DU receives SSB measurements for various SSB indices (e.g., SS-RSRP for SSB index = 1, 5, 7) of the candidate cell from the UE, and based on the mapping between the SSB index and the TCI state (or TCI state identifier), the serving DU determines which TCI state (or TCI state identifier) ​​of the candidate cell to include in the lower layer signaling. The included TCI state is the state that the UE should use when performing L1 / L2 inter-cell mobility execution.

[0099] Since the TCI state configuration of a candidate cell is generated by the candidate DU serving that cell, the serving DU needs to know the mapping between SSB indices and the TCI state (or identifiers) of the candidate cell. In one option, the mapping is provided to the serving DU by the candidate DU via the CU during the mobility preparation phase. In the preparation phase, the CU requests the candidate DU to configure L1 / L2 inter-cell mobility (for at least one candidate target cell) by sending a UE CONTEXT SETUP REQUEST containing an indication of a request for L1 / L2 inter-cell mobility. The candidate DU generates and sends a target candidate configuration containing the mapping between SSB indices (or other RS ​​indices and / or beam identifiers) and TCI state identifiers to the CU, for example, in an RRC container or as part of the F1AP message content / payload. The CU provides the mapping to the serving DU so that when the serving DU receives a report with measurements of the SSB index of a candidate cell, it can map that SSB index to the TCI state (or identifier) ​​of the candidate cell without necessarily knowing other details of its TCI state setting.

[0100] As a more specific example, a candidate DU may provide the following mapping to the serving DU (via the CU): ●SSB index = 3 ⇒ TCI state ID = 4 ●SSB index = 2 ⇒ TCI state ID = 6 ●SSB index = 7 ⇒ TCI state ID = 2 If the serving DU receives a report for a candidate cell indicating that SSB index=7 is the SSB with the strongest RSRP, RSRQ, and / or SINR, it shall include TCI state ID=2 in the lower layer signaling based on the provided mapping.

[0101] Figure 7 illustrates a signaling flow for configuring a UE (710) for inter-DU L1 / L2 inter-cell mobility from a serving DU (720) to a candidate DU (730), in accordance with these embodiments, where both DUs are associated with the same CU (740). In other words, the serving DU, candidate DU, and CU are part of a single RAN node (750). While the operations illustrated in Figure 7 are labeled with reference numbers, this is done for ease of explanation and does not require or imply any particular order of operations, unless explicitly stated otherwise.

[0102] In operation 1, the CU sends a UE CONTEXT SETUP REQUEST message to the candidate DU containing a request to configure L1 / L2 inter-cell mobility for the UE. In operation 2, the candidate DU responds with a UE CONTEXT SETUP RESPONSE message containing the configuration for the candidate cell that the candidate DU serves and the mapping between TCI state ID and SSB index for that candidate cell. In operation 3, the CU provides the same information to the UE's serving DU in a DL RRC MESSAGE TRANSFER message. If the CU has collected other candidate cell configurations (e.g., from other candidate DUs), the CU can include them in this message.

[0103] In operations 4-5, the serving DU sends an RRCReconfiguration message containing the configuration for the L1 / L2 inter-cell mobility candidate cell received from the CU to the UE, and the UE responds with an RRCReconfigurationComplete message. In operation 6, the serving DU responds to the CU with an UL RRC MESSAGE TRANSFER message.

[0104] In operation 7, the UE sends one or more CSI reports with measurement results of SSBs in the candidate cell to the serving DU, where the strongest measurement result is SSB index=X. The serving DU decides to trigger L1 / L2 inter-cell mobility of the UE to the candidate cell and maps SSB index=X to TCI state ID=Y based on the mapping received in operation 2. In operation 8, the serving DU sends lower layer signaling to the UE, including an identifier of the candidate cell and TCI state ID=Y. In operation 9, the UE sends an UL message to the candidate DU in the candidate cell based on applying TCI state ID=Y to the candidate cell.

[0105] In another embodiment, the indication of the TCI status is a beam configuration of the candidate cell. For example, the beam configuration may correspond to the beam or RS index for which the UE reported the strongest measurements (e.g., SSB RSRP, SSB SINR, SSB RSRQ) for the candidate cell. More specifically, this beam or RS index is configured as the QCL source for the indicated beam configuration.

[0106] For example, the serving DU receives from the UE one or more measurements for each RS index of the target candidate cell (e.g., RSRP for RS index=1, RSRP for RS index=5, and RSRP for RS index=7), and based on the mapping between the RS index and the beam configuration (or configuration identifier), the serving DU determines which beam configuration (or identifier) ​​of the candidate cell should be included in the lower layer signaling to the UE. The included beam configuration is the one that the UE should use when performing L1 / L2 inter-cell mobility execution.

[0107] Since the beam configuration of a candidate cell is generated by the candidate DU serving that cell, the serving DU needs to know the mapping between beam or RS index and the beam configuration (or identifier) ​​of the candidate cell, which can be handled in a similar way to the mapping between SSB index and TCI state (or identifier) ​​described above.

[0108] In another embodiment, the indication of the TCI state is a beam index or RS index that identifies an RS (e.g., SSB) as a QCL source for the TCI state. The UE selects the TCI state of a candidate cell to use during L1 / L2 inter-cell mobility based on the previously received candidate cell configuration and the beam or RS index. In particular, the UE selects the TCI state configuration in which the indicated beam index or RS index is configured as a QCL source.

[0109] For example, the indicated beam index or RS index may be the SSB index for which the UE has reported the strongest measurement (e.g., SSB RSRP, SSB SINR, SSB RSRQ) for the candidate cell. This SSB index is configured as the QCL source for a particular TCI state for the candidate cell. In other words, the serving DU receives SSB measurements for various SSB indices (e.g., SS-RSRP with SSB index=1, 5, 7) of the candidate cell from the UE and selects the SSB index corresponding to the strongest measurement.

[0110] For example, the indicated TCI state may be the TCI state corresponding to the SSB index for which the UE has reported the strongest measurement (e.g., SSB RSRP, SSB SINR, SSB RSRQ) for the candidate cell. This SSB index is set as the QCL source for the indicated TCI state. In other words, the serving DU receives measurements from the UE for various SSB indices of the candidate cell (e.g., SS-RSRP for SSB index=1, 5, 7), determines that SSB index=7 has the strongest measurement, and includes SSB index=7 in lower layer signaling to the UE.

[0111] Note that in these embodiments, the serving DU does not perform a mapping between SSB index and TCI state. Rather, upon receiving lower layer signaling, the UE selects a TCI state in which SSB index=7 is configured as the QCL source according to the previously received candidate cell configuration.

[0112] For example, the candidate cell configuration generated by the candidate DU and provided to the UE includes the following TCI state configuration: ● QCL source (e.g., D type) SSB index = 3 ⇒ TCI state ID = 4 ● QCL source (e.g., D type) SSB index = 2 ⇒ TCI state ID = 6 ● QCL source (e.g., D type) SSB index = 7 ⇒ TCI state ID = 2 If the serving DU receives a UE report indicating that SSB index=7 is the SSB with the strongest RSRP, RSRQ, and / or SINR for the candidate cell, the serving DU includes SSB index=7 in the lower layer signaling based on the provided mapping. The UE determines based on the candidate cell configuration that TCI state ID=2, in which SSB index=7 is the QCL source, should be used in the candidate cell.

[0113] As mentioned above, the serving DU does not need to know the mapping between the SSB index and the TCI state identifier of the candidate cell. Therefore, unlike the embodiment shown in Figure 7, the candidate DU does not need to provide the mapping between the SSB index and the TCI state identifier of the candidate cell to the CU or the serving DU during the preparation phase.

[0114] Figure 8 illustrates a signaling flow for configuring a UE (710) for inter-DU L1 / L2 inter-cell mobility from a serving DU (720) to a candidate DU (730), where both DUs are associated with the same CU (740). In other words, the serving DU, candidate DU, and CU are part of a single RAN node (750). While the operations illustrated in Figure 8 are labeled with reference numbers, this is done for ease of explanation and does not require or imply any particular order of operations unless explicitly stated otherwise.

[0115] Operations 1-7 are similar to the corresponding operations described above for Figure 7, except that the mapping between TCI State ID and SSB Index is not included in the messages of operations 2-3. In operation 8, the serving DU sends lower layer signaling to the UE, including the candidate cell's identifier and SSB Index = X. Based on the candidate cell configuration received in operation 4, the UE selects a TCI state (represented by TCI State ID = Y) in which SSB Index = X is configured as the QCL source. In operation 9, the UE sends a UL message to the candidate DU in the candidate cell based on applying TCI State ID = Y to the candidate cell.

[0116] In some embodiments, the serving DU may include in the lower layer signaling an indication of whether the UE should perform a random access (RA) procedure when performing L1 / L2 inter-cell mobility to a candidate cell. RA may not be required when the serving cell and the candidate cell overlap, are adjacent, or are in close proximity. As a specific example, the serving DU may decide to switch the UE's PCell to another cell (e.g., the current SCell for the UE) served by the same DU. Other conditions that may cause the serving DU to indicate the need for RA in a candidate cell are: The time alignment of the candidate cell is different from the time alignment of the source cell. the time alignment timer of the candidate cell has expired, and / or • The time alignment of the candidate cells is unknown.

[0117] In one example, the indication of whether the UE should perform RA may be explicit, such as a one-bit indication where "1" indicates that RA is required and "0" indicates that RA is not required. In another example, the indication of whether the UE should perform RA may be an index pointing to one of a set of pre-configured contention-free random access (CRFA) resources in the candidate cell configuration for L1 / L2 inter-cell mobility. The pre-configured resource may be an RA preamble, an RA occasion, an SSB, or a CSI-RS. In another example, the indication may explicitly indicate that contention-based random access (CBRA) should be used in the candidate cell in conjunction with L1 / L2 mobility.

[0118] In another example, the indication of whether the UE should perform RA may be an indication of whether the UE can maintain the time alignment of the serving cell when performing L1 / L2 inter-cell mobility to the candidate cell. Note that an indication that the UE can maintain the same time alignment as the serving cell implicitly indicates that the UE does not need to perform RA in the candidate cell, which would involve obtaining time alignment. In some variations, the indication may further indicate whether the UE can maintain the same DL time alignment, the same UL time alignment, both, or neither.

[0119] In some embodiments, the UE may determine whether an RA is required in a candidate cell in connection with L1 / L2 inter-cell mobility (e.g., at the UE's discretion) based on one or more of the following criteria: The time alignment of the candidate cell is different from the time alignment of the source cell. the candidate cell's time alignment timer has expired, and • The time alignment of the candidate cells is unknown.

[0120] In some embodiments, when the serving DU generates and sends to the UE lower layer signaling (e.g., MAC CE, DCI) indicating that the UE should perform L1 / L2 inter-cell mobility to the candidate cell, the serving DU further sends one or more of the following to the CU and / or the candidate DU: Indication of candidate cells selected by the serving DU for the UE's L1 / L2 inter-cell mobility, such as cell identifiers (e.g., PCI, CGI) or configuration identifiers Indication of the TCI state (e.g., TCI state ID, SSB index, etc.) of candidate cells used by the UE for L1 / L2 inter-cell mobility, and A copy or encapsulation of lower layer signaling for L1 / L2 inter-cell mobility that the serving DU has sent or will send to the UE, including an indication of the selected candidate cell and TCI state. Based on receiving such information, the candidate DU can determine that the incoming UE should use the particular TCI state in the candidate cell and communicate with the UE accordingly.

[0121] Figure 9 shows signaling for another exemplary procedure for a CU (740) configuring a UE (710) for L1 / L2 inter-cell mobility from a serving DU (720) to a candidate DU (730), both associated with the CU, according to some of these embodiments. In other words, the serving DU, candidate DU, and CU are part of a single RAN node (750). Because Figure 9 illustrates many of the same operations as Figures 7-8, a description of these operations in Figure 9 will be omitted below for brevity.

[0122] In Figure 9, the UE receives lower layer signaling including a target candidate cell indication and a TCI state ID. The serving DU generates the TCI state ID in the lower layer signaling based on a mapping between the SSB index of the candidate cell and the TCI state ID previously received from the candidate DU via the CU. More specifically, the serving DU determines the TCI state ID of the candidate cell based on measurement information reported from the UE for at least one SSB index of the candidate cell.

[0123] When the serving DU sends lower layer signaling to the UE, it also sends an indication (including the TCI state ID) to the CU, which in turn sends it to the candidate DU, which updates the CU with the latest cell the UE is attached to, but also indicates to the candidate DU that the incoming UE should use the TCI state in the candidate cell.

[0124] The serving DU may send the L1 / L2 inter-cell mobility indication (including the TCI state ID) to the CU before or after sending the lower layer signaling to the UE, including after receiving an acknowledgment for the lower layer signaling from the UE. Alternatively, the serving DU may wait a predetermined time after sending the lower layer signaling to send the TCI state ID to the CU.

[0125] Figure 10 shows signaling for another exemplary procedure in which a CU (740) configures a UE (710) for L1 / L2 inter-cell mobility from a serving DU (720) to a candidate DU (730), where both DUs are associated with the CU. In other words, the serving DU, candidate DU, and CU are part of a single RAN node (750). Because Figure 10 shows many of the same operations as Figures 7-8, descriptions of these operations in Figure 10 will be omitted below for brevity.

[0126] 10, the UE receives lower layer signaling including an indication of a candidate cell and an SSB index (operation 8). The UE determines the TCI state ID of the active candidate cell by configuring it as a QCL source (e.g., for QCL type D or other types related to spatial directional correlation) and activating the TCI state with the received SSB index.

[0127] When the serving DU sends lower layer signaling to the UE, it also sends an indication (including the SSB index) to the CU, which forwards it to the candidate DU. This updates the CU with the most recent cell the UE is attached to, but also indicates to the candidate DU that the incoming UE will use the SSB index (or corresponding TCI state) in the candidate cell.

[0128] The serving DU may send the L1 / L2 inter-cell mobility indication (including the SSB index) to the CU before or after sending the lower layer signaling to the UE, including after receiving an acknowledgment of the lower layer signaling from the UE. Alternatively, the serving DU may wait a predetermined time after sending the lower layer signaling to send the SSB index to the CU.

[0129] In some variations of the embodiments shown in Figures 9-10, upon receiving the lower layer signaling, the UE does not transmit an uplink message in the candidate cell (operation 9), but first monitors the PDCCH of the candidate cell according to an indication (e.g., a TCI state ID or SSB index mapped to a TCI state by the UE) included in the lower layer signaling. If the serving DU knows in advance that the UE will first monitor the PDCCH of the candidate cell before transmitting the UL message in operation 9, the serving DU triggers operation 8a. Otherwise, if the serving DU knows that the UE will directly transmit on the UL (operation 9), operation 8a can be omitted. In the case where the lower layer signaling triggers the UE to perform random access, the UE selects a beam (e.g., an SSB index / CSI-RS resource identifier) ​​and transmits a preamble associated with the selected beam, so that the candidate DU can recognize the beam selected by the UE. Therefore, an indication of which TCI state ID and / or beam ID and / or SSB index may not be required in operation 8.

[0130] In some embodiments, upon receiving lower layer signaling with an indication that a random access procedure is not required when performing L1 / L2 inter-cell mobility to the target candidate cell, the UE begins transmitting UL messages in the target candidate cell, in this case the first UL message that the UE can transmit in the candidate cell for L1 / L2 inter-cell mobility is UL data or a scheduling request.

[0131] In some embodiments, an indication of L1 / L2 inter-cell mobility execution, including the candidate cell and possibly the TCI state ID and / or SSB index, is provided from the serving DU to the CU in a UE CONTEXT MODIFICATION REQUIRED message via the F1 AP (operation 8a). The CU provides this information to the candidate DU in a UE CONTEXT MODIFICATION REQUEST message via the F1 AP (operation 8b).

[0132] In some embodiments, the UE receives an indication of whether the UE should perform a MAC reset when performing L1 / L2 inter-cell mobility to a candidate cell. In one example, this indication is provided within lower layer signaling indicating the performance of L1 / L2 inter-cell mobility to the candidate cell (e.g., operation 8 of FIG. 10 ). In another example, this indication is provided within the configuration of one or more L1 / L2 inter-cell mobility candidate cells (e.g., operation 4 of FIG. 10 ). In various embodiments, the MAC reset can include one or more of the following actions: Initializing state variables Stopping, starting, or restarting a timer Setting the New Data Indicator (NDI) for the UL HARQ process to 0 Stopping an ongoing MAC procedure Canceling a triggered MAC procedure Flushing the message buffer Resetting the counter, and ● Releasing the C-RNTI.

[0133] In some embodiments, the UE selectively performs a MAC reset when performing L1 / L2 inter-cell mobility to a candidate cell, such as by not performing any, some, or all of the actions listed above. For example, this selective action is based on an indication received from the serving DU, such as the type (e.g., DCI or MAC CE) or content of lower layer signaling indicating the execution of L1 / L2 inter-cell mobility. Alternatively, the indication may be part of the candidate cell configuration received via higher layer signaling.

[0134] In some embodiments, the serving DU receives an indication from the CU and / or from the candidate DU as to whether the UE needs to perform a MAC reset when performing L1 / L2 inter-cell mobility to one of the L1 / L2 inter-cell mobility candidate cells configured for the UE.

[0135] In some embodiments, the serving DU sends an indication to the CU and / or candidate DU as to whether the UE needs to perform a MAC reset when performing L1 / L2 inter-cell mobility to one of the L1 / L2 inter-cell mobility candidate cells configured for the UE.

[0136] In some embodiments, the serving DU determines whether the UE needs to perform a MAC reset when performing L1 / L2 inter-cell mobility to the candidate cell and sets this indication accordingly. In one example, this determination is based on an indication received from the CU and / or the candidate DU. In another example, this determination is based on whether both the source and candidate target cells are controlled by the same DU. For example, the indication may indicate that the UE should not perform a MAC reset when performing L1 / L2 inter-cell mobility to the candidate cell if both the source and candidate target cells are controlled by the same DU. In another example, this determination is based on whether both the source and candidate target cells are controlled by the same hardware or software unit.

[0137] In some embodiments, the CU transmits an indication to the UE regarding whether the UE needs to perform a MAC reset when performing L1 / L2 inter-cell mobility to a candidate cell. In one example, this indication is provided in the configuration of one or more applicable L1 / L2 inter-cell mobility candidate cells.

[0138] In some embodiments, the CU receives an indication from the serving DU or candidate DU regarding whether the UE needs to perform a MAC reset when performing L1 / L2 inter-cell mobility to one of the L1 / L2 inter-cell mobility candidate cells configured for the UE.

[0139] In some embodiments, the CU sends an indication to the serving DU or candidate DU regarding whether the UE needs to perform a MAC reset when performing L1 / L2 inter-cell mobility to one of the L1 / L2 inter-cell mobility candidate cells configured for the UE.

[0140] In some embodiments, the CU determines whether the UE needs to perform a MAC reset when performing L1 / L2 inter-cell mobility to a candidate cell and sets this indication accordingly. In various embodiments, this determination is based on one or more of the following: Explicit indication from the Serving DU or Candidate DU Whether the source and candidate target cells are both controlled by the same DU (e.g., the UE does not need to perform a MAC reset if the source and candidate cells are both controlled by the same DU) • Whether the source and candidate target cells are both controlled by the same hardware or software unit.

[0141] In some embodiments, the candidate DU receives an indication from the serving DU or CU as to whether the UE needs to perform a MAC reset when performing L1 / L2 inter-cell mobility to one of the L1 / L2 inter-cell mobility candidate cells configured for the UE.

[0142] In some embodiments, the candidate DU sends an indication to the serving DU or CU as to whether the UE needs to perform a MAC reset when performing L1 / L2 inter-cell mobility to one of the L1 / L2 inter-cell mobility candidate cells configured for the UE.

[0143] In some embodiments, the candidate DU determines whether the UE needs to perform a MAC reset when performing L1 / L2 inter-cell mobility to the candidate cell and sets this indication accordingly. In various embodiments, this determination is based on one or more of the following: Explicit indication from the serving DU or CU Whether the source and candidate target cells are both controlled by the same DU (e.g., the UE does not need to perform a MAC reset when the source and candidate cells are both controlled by the same DU). • Whether the source and candidate target cells are both controlled by the same hardware or software unit.

[0144] The above-described embodiments can be further illustrated with reference to FIGS. 11-13, which illustrate example methods (e.g., procedures) for a UE, a serving DU, and a candidate DU, respectively. In other words, various features of the operations described below correspond to the various embodiments described above. The example methods illustrated in FIGS. 11-13 may be used cooperatively to provide benefits, advantages, and / or solutions to problems described herein. Although FIGS. 11-13 illustrate the example methods with particular blocks in a particular order, the operations corresponding to the blocks may be performed in a different order than shown, and may be combined and / or divided into blocks and / or operations having different functionality than shown. Any blocks or operations are indicated by dashed lines.

[0145] More specifically, Figure 11 illustrates an example method (e.g., procedure) for a UE configured to communicate with a RAN node, including a CU and a DU, that provides a serving cell for the UE, in accordance with various embodiments of the present disclosure. The example method illustrated in Figure 11 can be performed by a UE (e.g., a wireless device) as described elsewhere herein.

[0146] The example method may include the operation of block 1150, in which the UE may receive a lower layer signaling message from the DU indicating that the UE should perform L1 / L2-based inter-cell mobility to a first candidate cell provided by the candidate DU. The lower layer signaling message includes an indicator or identification of the first candidate cell and an indication of a first TCI state to be used by the UE to communicate with the first candidate cell. The example method may further include the operation of block 1170, in which the UE may perform an L1 / L2 mobility procedure toward the first candidate cell and communicate in the first candidate cell based on the first TCI state.

[0147] In some embodiments, the indication of the first TCI state is a TCI state identifier or an index of a first beam or reference signal (RS) transmitted in the first candidate cell. In some of these embodiments, the example method may also include operations of blocks 1110 and 1160. In block 1110, the UE may receive, from the CU via the DU, an RRCReconfiguration message including configurations associated with one or more candidate cells for L1 / L2-based inter-cell mobility, including the first candidate cell. Each candidate cell configuration includes multiple TCI state configurations, and each TCI state configuration includes an index of a beam or RS arranged as a quasi-co-located (QCL) source. In block 1160, the UE may select, as the first TCI state, one of the TCI state configurations including the index of the first beam or RS as a QCL source.

[0148] In some of these embodiments, the example method may also include the operation of block 1120, in which the UE may send an RRCReconfigurationComplete message to the CU via the DU in response to the RRCReconfiguration message. In some of these embodiments, the configuration for the first candidate cell (e.g., in block 1110), or one of the messages compatible with lower layer signaling, includes an indication of whether the UE should perform a MAC reset when performing L1 / L2 inter-cell mobility to the first candidate cell. In some variations of these embodiments, performing an L1 / L2 mobility procedure toward the first candidate cell in block 1170 includes the operation of sub-block 1171, where, based on the indication of whether the UE should perform a MAC reset, the UE may selectively perform one or more of the following operations: Initializing MAC state variables Stopping, starting, or restarting a MAC timer Resetting the New Data Indicator (NDI) for the uplink hybrid ARQ process to 0 Stopping an ongoing MAC procedure Canceling a MAC procedure that has been triggered but is not in progress Flushing (emptying) the MAC message buffer Resetting the MAC counter, and ● Releasing the Radio Network Temporary Identifier (RNTI) assigned to the UE.

[0149] In some embodiments, the lower layer signaling message further includes an indication of whether the UE should perform a random access (RA) procedure when performing L1 / L2 inter-cell mobility to the first candidate cell. In some of these embodiments, performing the L1 / L2 mobility procedure toward the first candidate cell in block 1170 includes operations of sub-block 1172, where the UE can selectively perform the RA procedure in the first candidate cell based on one or more of the following: Indication of whether the UE should perform an RA procedure Whether the first candidate cell time alignment is different from the serving cell time alignment whether the time alignment timer of the first candidate cell has expired; and • Whether the time alignment of the first candidate cell is known or unknown.

[0150] In some embodiments, the exemplary method may further include operations of blocks 1130-1140, where the UE may perform measurements on multiple beams or RSs transmitted in the first candidate cell and transmit results of the measurements to the DU. In such cases, the first TCI state corresponds to an index of a beam or RS having a measurement result that is most favorable for L1 / L2 mobility to the first candidate cell. In some of these embodiments, the multiple beams or RSs include one or more of a synchronization signal / PBCH block (SSB) and a channel state information reference signal (CSI-RS).

[0151] In some embodiments, one or more of the following apply: the lower layer signaling message is for a protocol layer below the RRC protocol layer, and the lower layer signaling message is one of a MAC Control Element (CE) or a physical layer Downlink Control Information (DCI). In some embodiments, the candidate DU is associated with a CU and / or is part of a RAN node.

[0152] In some embodiments, communicating in the first candidate cell based on the first TCI state in block 1170 includes one or more of the following operations, as indicated by corresponding subblock numbers: ● (1173) Monitoring a downlink control channel of a first candidate cell in a beam or spatial direction corresponding to a first TCI state; ● (1174) Transmitting uplink data or a scheduling request to the first candidate cell in a beam or spatial direction corresponding to the first TCI state.

[0153] 12 illustrates an example method (e.g., procedure) for a DU of a RAN node to communicate with a CU of the RAN node and to provide a serving cell for a UE, in accordance with various embodiments of the present disclosure. The example method illustrated in FIG. 12 may be performed by providing a serving DU as described elsewhere herein.

[0154] The example method may include the operation of block 1250, in which the DU may select a first candidate cell provided by the candidate DU for L1 / L2-based inter-cell mobility of a UE served by the DU via the serving cell. The example method may further include the operation of block 1280, in which the DU may transmit a lower layer signaling message to the UE indicating that the UE should perform L1 / L2-based inter-cell mobility to the first candidate cell. The lower layer signaling message includes an indicator or identification of the first candidate cell and an indication of a first TCI state to be used by the UE to communicate with the first candidate cell.

[0155] In some embodiments, the exemplary method may also include the operation of block 1240, in which the DU may receive from the UE results of measurements performed by the UE on multiple beams or RSs transmitted in the first candidate cell. The measurement results include indexes of each of the multiple beams or RSs. In some of these embodiments, the multiple beams or RSs include one or more of an SSB and a CSI-RS.

[0156] In some of these embodiments, the first TCI state is associated with a first beam or RS having the most favorable measurement results (e.g., highest SS-RSRP) for L1 / L2 mobility to the first candidate cell. In some variations of these embodiments, the indication of the first TCI state is one of an index of the first beam or RS or a TCI state identifier.

[0157] In some further variations of these embodiments, the exemplary method may also include the operation of block 1260, in which the DU may determine a TCI state identifier for the first TCI state based on an index of a first beam or RS that is an indication of the first TCI state and a mapping between a TCI state identifier used in the first candidate cell and an index of a beam or RS transmitted in the first candidate cell. In some further variations, the exemplary method may also include the operation of block 1205, in which the DU may receive the mapping (e.g., used in block 1260) from a candidate DU or CU.

[0158] In some embodiments, the example method may also include the operation of block 1290, where the DU may send a message to the CU or candidate DU that includes one or more of the following: Indicator or identity of first candidate cell for L1 / L2 based inter-cell mobility of the UE an indication of a first TCI state used by the UE to communicate with the first candidate cell; and ● A copy or encapsulation of the lower layer signaling message (eg, sent or transmitted to the UE in block 1280).

[0159] In some embodiments, the lower layer signaling message in block 1280 may also include one or more of the following: an indication of whether the UE should perform an RA procedure when performing L1 / L2 inter-cell mobility to the first candidate cell; and ●An indication of whether the UE should perform a MAC reset when performing L1 / L2 inter-cell mobility to the first candidate cell. In some of these embodiments, the example method may also include the operation of block 1270, in which the UE may determine whether to perform an RA procedure when the DU performs L1 / L2 inter-cell mobility to the first candidate cell, as indicated in the lower layer signaling message, based on one or more of the following: Whether the time alignment of the first candidate cell is different from the time alignment of the serving cell whether the time alignment timer of the first candidate cell has expired; and • Whether the time alignment of the first candidate cell is known or unknown.

[0160] In some embodiments, the lower layer signaling message is for a protocol layer below the RRC protocol layer, and / or the lower layer signaling message is a MAC CE or DCI of the PHY. In some embodiments, the candidate DU is associated with a CU and / or is part of a RAN node.

[0161] In some embodiments, the exemplary method may also include the DU performing the following operations, labeled with the corresponding block numbers: (1210) Sending a request to a CU or a candidate DU to configure a UE with at least one candidate cell for L1 / L2-based inter-cell mobility. (1220) Receiving, from the CU or the candidate DU, configurations for one or more candidate cells provided by the candidate DU, including the first candidate cell. (1230) Send the configuration to the UE in an RRCReconfiguration message.

[0162] 13 illustrates an example method (e.g., procedure) for a candidate DU of a RAN node, according to various embodiments of the present disclosure. The example method illustrated in FIG. 13 may be performed by the candidate DU as described elsewhere herein.

[0163] The example method may include the operation of block 1320, in which the candidate DU may receive a request from a CU or from a DU serving the UE via a serving cell to configure the UE with at least one candidate cell for L1 / L2-based inter-cell mobility. The example method may further include the operation of block 1330, in which the candidate DU may transmit configurations for one or more candidate cells provided by the candidate DU, including a first candidate cell, to the CU or DU. The example method may further include the operation of block 1340, in which the candidate DU may receive a message from the DU indicating an L1 / L2 mobility procedure by the UE. The message includes an indicator or identification of the first candidate cell for the UE's L1 / L2-based inter-cell mobility and an indication of a first TCI state to be used by the UE to communicate with the first candidate cell. The example method may also include the operation of block 1360, in which the candidate DU may communicate with the UE in the first candidate cell based on the first TCI state.

[0164] In some embodiments, the DU is associated with the CU and / or is part of a RAN node. In some embodiments, the indicator or identity of the first candidate cell and the indication of the first TCI state are received as a copy or encapsulated in a lower layer signaling message sent by the DU to the UE.

[0165] In some embodiments, the indication of the first TCI state is an index of a first beam or RS transmitted in the candidate cell. In such embodiments, the example method may further include the operation of block 1350, where the candidate DU may determine the first TCI state or an identifier thereof based on the index of the first beam or RS and a mapping between a TCI state identifier used in the first candidate cell and the index of the beam or RS transmitted in the first candidate cell.

[0166] In another embodiment, the indication of the first TCI state is a TCI state identifier, and the exemplary method further includes the operation of block 1310, in which the candidate DU may transmit to the CU or DU a mapping between the TCI state identifier used in the first candidate cell and the index of the beam or RS transmitted in the first candidate cell.

[0167] In some embodiments, the configuration for the first candidate cell (e.g., transmitted in block 1330) includes an indication of whether the UE should perform a MAC reset when performing L1 / L2 inter-cell mobility to the first candidate cell.

[0168] In some embodiments, communicating with the UE in the first candidate cell based on the first TCI state in block 1360 includes one or more of the following operations, as indicated by corresponding subblock numbers: (1361) Transmitting a downlink control channel of a first candidate cell in a beam or spatial direction corresponding to a first TCI state. ● (1362) Receiving uplink data or a scheduling request from the UE of the first candidate cell in a beam or spatial direction corresponding to the first TCI state.

[0169] While various embodiments are described above with respect to methods, techniques, and / or procedures, those skilled in the art will readily appreciate that such methods, techniques, and / or procedures may be implemented by various combinations of hardware and software in various systems, communication devices, computing devices, control devices, apparatus, non-transitory computer-readable media, computer program products, etc.

[0170] 14 illustrates an example of a communications system 1400 according to some embodiments. In this example, the communications system 1400 includes a telecommunications network 1402 including an access network 1404 (e.g., a RAN) and a core network 1406 including one or more core network nodes 1408. The access network 1404 includes one or more access network nodes, such as network nodes 1410 a-b (one or more of which may be generally referred to as network nodes 1410), or some other similar 3GPP access node or non-3GPP access point. The network nodes 1410 facilitate direct or indirect connectivity of UEs 1412 a-d (one or more of which may be generally referred to as UEs 1412), such as connecting UEs 1412 a-d to the core network 1406 over one or more wireless connections.

[0171] Exemplary wireless communications over wireless connections include transmitting and / or receiving wireless signals using electromagnetic waves, radio waves, infrared, and / or other types of signals suitable for carrying information without the use of wires, cables, or other material conductors. Moreover, in various embodiments, communications system 1400 may include any number of wired or wireless networks, network nodes, UEs, and / or any other components or systems that may facilitate or participate in the communication of data and / or signals, whether via wired or wireless connections. Communications system 1400 may include and / or interface with any type of communications, telecommunications, data, cellular, wireless networks, and / or other similar types of systems.

[0172] The UE 1412 may be any of a wide variety of communication devices, including a wireless device, that is positioned, configured, and / or operable to communicate wirelessly with the network node 1410 and other communication devices. Similarly, the network node 1410 is positioned, capable, configured, and / or operable to communicate, directly or indirectly, with the UE 1412 and / or with other network nodes or equipment within the telecommunications network 1402 to enable and / or provide network access, such as wireless network access, and / or to perform other functions, such as management within the telecommunications network 1402.

[0173] In the illustrated example, the core network 1406 connects the network node 1410 to one or more hosts, such as the host 1416. The connections may be direct or indirect through one or more intermediate networks or devices. In other examples, the network nodes may be directly coupled to the hosts. The core network 1406 includes one or more core network nodes (e.g., 1408) structured with hardware and software components. The functionality of those components may be substantially similar to that described with respect to the UEs, network nodes, and / or hosts, and thus those descriptions are generally applicable to the corresponding components of the core network node 1408. Exemplary core network nodes include one or more of the following functions: a Mobile Switching Center (MSC), a Mobility Management Entity (MME), a Home Subscriber Server (HSS), an Access and Mobility Management Function (AMF), a Session Management Function (SMF), an Authentication Server Function (AUSF), a Subscription Identifier Deciphering Function (SIDF), a Unified Data Management (UDM), a Security Edge Protection Proxy (SEPP), a Network Exposure Function (NEF), and / or a User Plane Function (UPF).

[0174] Host 1416 may be owned or controlled by, and operated by or on behalf of, a non-operator service provider or provider of access network 1404 and / or telecommunications network 1402. Host 1416 may host a variety of applications to provide one or more services. Examples of such applications include live and pre-recorded audio / video content, data collection services such as acquiring and compiling data about various ambient conditions sensed by multiple UEs, analytics functionality, social media, functionality for controlling or otherwise interacting with remote devices, functionality for alarm and monitoring centers, or any other such functionality performed by a server.

[0175] 14 enables connectivity between UEs, network nodes, and hosts. In that sense, the communication system may be configured to operate according to predefined rules or procedures, such as a particular standard, including, but not limited to, Global System for Mobile Communications (GSM), Universal Mobile Telecommunications System (UMTS), Long Term Evolution (LTE), and / or other suitable 2G, 3G, 4G, 5G standards, or any applicable future generation standard (e.g., 6G), a wireless local area network (WLAN) standard, such as the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard (WiFi), and / or any other suitable wireless communication standard, such as Worldwide Interoperability for Microwave Access (WiMax), Bluetooth, Z-Wave, Near Field Communication (NFC), ZigBee, LiFi, and / or any low-power wide-area network (LPWAN) standard, such as LoRa and Sigfox.

[0176] In some examples, the telecommunications network 1402 is a cellular network that implements functions standardized by 3GPP. Thus, the telecommunications network 1402 may support network slicing to provide different logical networks to different devices connected to the telecommunications network 1402. For example, the telecommunications network 1402 may provide Ultra-Reliable Low Latency Communications (URLLC) services to some UEs, while providing enhanced Mobile Broadband (eMBB) services to other UEs and / or providing Massive Machine Type Communications (mMTC) / Massive IoT services to additional UEs.

[0177] In some examples, the UE 1412 is configured to transmit and / or receive information without direct human interaction. For example, the UE may be designed to transmit information to the access network 1404 on a predetermined schedule, when triggered by an internal or external event, or in response to a request from the access network 1404. Additionally, the UE may be configured to operate in a single or multi-RAT or multi-standard mode. For example, the UE may be configured and operate in any one or combination of Wi-Fi, NR (New Radio), and LTE, i.e., for Multi-Radio Dual Connectivity (MR-DC), such as E-UTRAN (Evolved-UMTS Terrestrial Radio Access Network) New Radio-Dual Connectivity (EN-DC).

[0178] In the above example, hub 1414 communicates with access network 1404 to facilitate indirect communication between one or more UEs (e.g., UE 1412c and / or 1412d) and a network node (e.g., network node 1410b). In some examples, hub 1414 may be a controller, router, content source and analyzer, or any of the other communication devices described herein with respect to UEs. For example, hub 1414 may be a broadband router that enables access to core network 1406 for the UE. As another example, hub 1414 may be a controller that sends commands or instructions to one or more actuators in the UE. The commands or instructions may be received from the UE or the network node 1410, or may be accepted by executable code, scripts, processes, or other instructions in hub 1414. As another example, hub 1414 may be a data collector that acts as temporary storage for UE data and, in some embodiments, may perform analysis or other processing of that data. As another example, hub 1414 may be a content source. For example, for a UE that is a VR headset, display, loudspeaker, or other media delivery device, the hub 1414 may obtain media or data related to VR assets, video, audio, or other sensory information via a network node, and then provide it to the UE either directly, after performing local processing, and / or after adding additional local content. In yet another example, the hub 1414 acts as a proxy server or orchestrator for the UEs, particularly if one or more of the UEs are low-energy IoT devices.

[0179] The hub 1414 may have a constant / permanent or intermittent connection to the network node 1410b. The hub 1414 may also enable different communication schemes and / or schedules between the hub 1414 and UEs (e.g., UEs 1412c and / or 1412d) and between the hub 1414 and the core network 1406. In other examples, the hub 1414 is connected to the core network 1406 and / or one or more UEs via a wired connection. Moreover, the hub 1414 may be configured to connect to an M2M service provider over the access network 1404 and / or to other UEs over a direct connection. In some scenarios, a UE may establish a wireless connection with the network node 1410b while still being connected via the hub 1414 via a wired or wireless connection. In some embodiments, the hub 1414 may be a dedicated hub, i.e., a hub whose primary function is to route communications between UEs and the network node 1410b. In other embodiments, the hub 1414 may be a non-dedicated hub, i.e., a device that is operable to route communications between the UE and the network node 1410b, but that is also operable as an origin and / or terminator of communications for any data channel.

[0180] 15 illustrates a UE 1500 according to some embodiments. Examples of a UE include, but are not limited to, a smartphone, a mobile phone, a cell phone, a Voice over IP (VoIP) phone, a wireless local loop phone, a desktop computer, a personal digital assistant (PDA), a wireless camera, a game console or device, a music storage device, a playback appliance, a wearable terminal device, a wireless endpoint, a mobile station, a tablet, a laptop, a laptop embedded equipment (LEE), a laptop mounted equipment (LME), a smart device, a wireless customer premises equipment (CPE), a vehicle, an in-vehicle or vehicle embedded / integrated wireless device, etc. Other examples include a Narrowband Internet of Things (NB-IoT) UE, a Machine Type Communication (MTC) UE, and / or any UE identified by the 3rd Generation Partnership Project (3GPP), including an enhanced MTC (eMTC) UE.

[0181] A UE may support device-to-device (D2D) communications, for example, by implementing 3GPP standards for sidelink communications, dedicated short-range communications (DSRC), vehicle-to-vehicle (V2V), vehicle-to-infrastructure (V2I), or vehicle-to-everything (V2X). In other examples, a UE may not necessarily have a user in the sense of a human user who owns and / or operates the associated device. Instead, a UE may represent a device (e.g., a smart sprinkler controller) that is intended for sale to or operation by a human user, but that may not, at least initially, be associated with a particular human user. Alternatively, a UE may represent a device (e.g., a smart power meter) that is not intended for sale to or operation by an end user, but that may be associated with or operated for the benefit of a user.

[0182] The UE 1500 includes a processing circuit 1502, a power supply 1508, a memory 1510, a communication interface 1512, and / or any other components operably coupled via a bus 1504 to an input / output interface 1506, or any combination thereof. A given UE may utilize all or a subset of the components shown in FIG. 15. The level of integration between components may vary from one UE to another. Furthermore, a given UE may include multiple instances of a component, such as multiple processors, memories, transceivers, transmitters, receivers, etc.

[0183] The processing circuit 1502 is configured to process instructions and data, and may be configured to implement any sequential state machine operable to execute instructions stored as a machine-readable computer program in the memory 1510. The processing circuit 1502 may be implemented as one or more hardware-implemented state machines (e.g., in discrete logic, a field programmable gate array (FPGA), an application-specific integrated circuit (ASIC), etc.), programmable logic with appropriate firmware, one or more stored computer programs, a general-purpose processor such as a microprocessor or digital signal processor (DSP) with appropriate software, or any combination of the above. For example, the processing circuit 1502 may include multiple central processing units (CPUs).

[0184] In the above examples, the input / output interface 1506 may be configured to provide one or more interfaces to an input device, an output device, or one or more input and / or output devices. Examples of output devices include speakers, sound cards, video cards, displays, monitors, printers, actuators, emitters, smart cards, other output devices, or any combination thereof. The input device may enable a user to capture information for the UE 1500. Examples of input devices include touch-sensitive or presence-sensitive displays, cameras (e.g., digital cameras, digital video cameras, webcams, etc.), microphones, sensors, mice, trackballs, directional pads, trackpads, scroll wheels, smart cards, etc. The presence-sensitive display may include a capacitive or resistive touch sensor for sensing input from a user. The sensor may be, for example, an accelerometer, a gyroscope, a tilt sensor, a force sensor, a magnetic sensor, an optical sensor, a proximity sensor, a biometric sensor, etc., or any combination thereof. The output device may use the same type of interface port as the input device. For example, a Universal Serial Bus (USB) port may be used to provide input and output devices.

[0185] In some embodiments, the power source 1508 is structured as a battery or battery pack. Other types of power sources, such as an external power source (e.g., an electrical outlet), a solar-powered device, or batteries, may also be used. The power source 1508 may further include power circuitry for transferring power from the power source 1508 itself and / or the external power source to various parts of the UE 1500 via interfaces, such as input circuits or power cables. The power transfer may be for charging the power source 1508, for example. The power circuitry may perform some shaping, conversion, or other modification of the power from the power source 1508 to make it suitable for the respective components of the UE 1500 that it powers.

[0186] The memory 1510 may be or be configured to include random access memory (RAM), read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), magnetic disk, optical disk, hard disk, removable cartridge, flash drive, etc. In one example, the memory 1510 includes one or more application programs 1514, such as an operating system, a web browser application, widgets, gadget engine, or other applications, and corresponding data 1516. The memory 1510 may store any of a wide variety of operating systems or combinations of operating systems for use by the UE 1500.

[0187] The memory 1510 may be configured to include multiple physical drive units such as a redundant array of independent disks (RAID), flash memory, a USB flash drive, an external hard disk drive, a thumb drive, a pen drive, a key drive, a high-density digital versatile disc (HD-DVD), an optical disk drive, an internal hard disk drive, a Blu-ray optical disk drive, a holographic digital data storage (HDDS) optical disk drive, an external mini-DIMM (Dual In-Line Memory Module), a synchronous dynamic random access memory (SDRAM), an external micro-DIMM (SDRAM), a smart card memory such as a tamper-resistant module in the form of a universal integrated circuit card (UICC) including one or more subscriber identity modules (SIMs) such as a USIM and / or ISIM, other memory, or any combination thereof. The UICC may be, for example, an embedded UICC (eUICC), an integrated UICC (iUICC), or a removable UICC commonly known as a "SIM card." The memory 1510 may enable the UE 1500 to access instructions, application programs, and the like stored on a transient or non-transitory memory medium to offload or upload data. An item of manufacture, such as one utilizing a communication system, may be tangibly embodied as or within the memory 1510, which may be or include a device-readable storage medium.

[0188] The processing circuit 1502 may be configured to communicate with an access network or other networks using a communication interface 1512. The communication interface 1512 may include one or more communication subsystems and may include or be communicatively coupled to an antenna 1522. The communication interface 1512 may include one or more transceivers used to communicate, such as by communicating with one or more remote transceivers of other wirelessly capable devices (e.g., other UEs or network nodes within the access network). Each transceiver may include a transmitter 1518 and / or receiver 1520 appropriate for providing network communications (e.g., optical, electrical, frequency-assigned, etc.). Moreover, the transmitter 1518 and receiver 1520 may be coupled to one or more antennas (e.g., 1522), which may share circuit components, software, or firmware, or may alternatively be implemented separately.

[0189] In the illustrated embodiment, the communication capabilities of communication interface 1512 may include cellular communication, Wi-Fi communication, LPWAN communication, data communication, voice communication, multimedia communication, short-range communication such as Bluetooth, near-field communication, location-based communication such as using the Global Positioning System (GPS) for determining location, other similar communication capabilities, or any combination thereof. Communications may be implemented according to one or more communication protocols and / or standards, such as, for example, IEEE 802.11, Code Division Multiple Access (CDMA), Wideband Code Division Multiple Access (WCDMA), GSM, LTE, New Radio (NR), UMTS, WiMax, Ethernet, Transmission Control Protocol / Internet Protocol (TCP / IP), Synchronous Optical Networking (SONET), Asynchronous Transfer Mode (ATM), QUIC, Hypertext Transfer Protocol (HTTP), etc.

[0190] Regardless of the type of sensor, the UE may provide an output of data captured by its sensors to a network node via a wireless connection through its communication interface 1512. Data captured by the UE's sensors may be communicated via other UEs to the network node via a wireless connection. The output may be periodic (e.g., once every 15 minutes when reporting sensed temperature), random (e.g., to balance the load of reporting from multiple sensors), in response to a triggering event (e.g., moisture detected and an alert sent), on request (e.g., a user-initiated request), or as a continuous stream (e.g., a live video feed of a patient).

[0191] As another example, the UE may include an actuator, motor, or switch associated with a communications interface configured to receive wireless input from a network node via a wireless connection. The state of the actuator, motor, or switch may change in response to the received wireless input. For example, the UE may include a motor that adjusts a control surface or rotor of a drone in flight in accordance with the received input, or a robotic arm that performs a medical procedure in accordance with the received input.

[0192] When the UE is in the form of an Internet of Things (IoT) device, it may be a device for use in one or more application domains, including but not limited to wearable technology in the city, extended industrial applications, and healthcare. Non-limiting examples of such IoT devices include, or are incorporated into, devices such as a connected refrigerator or freezer, a TV, a connected lighting fixture, an electric meter, a robot vacuum, a voice-controlled smart speaker, a home security camera, a motion detector, a thermostat, a smoke detector, a door / window sensor, a flood / moisture sensor, an electric door lock, a connected doorbell, an air conditioning system such as a heat pump, an autonomous vehicle, a surveillance system, a weather monitoring device, a vehicle parking monitoring device, an electric vehicle charging station, a smart watch, a fitness tracker, a head-mounted display for augmented reality (AR) or virtual reality (VR), a wearable for haptic augmentation or sensory enhancement, a water sprinkler, an animal or object tracking device, a sensor for monitoring plants or animals, an industrial robot, an unmanned aerial vehicle (UAV), and any type of medical device such as a heart rate monitor or a remote-controlled surgical robot. A UE in the form of an IoT device comprises other components such as those described in connection with the UE 1500 shown in FIG. 15, in addition to circuitry and / or software depending on the intended application of the IoT device.

[0193] As yet another specific example, in an IoT scenario, a UE may represent a machine or other device that performs monitoring and / or measurements and transmits results of such monitoring and / or measurements to other UEs and / or network nodes. The UE, in this case, may be an M2M device, which may also be referred to as an MTC device in the 3GPP context. As one particular example, the UE may implement the 3GPP NB-IoT standard. In other scenarios, a UE may represent a vehicle, such as a car, bus, truck, ship, or aircraft, or other equipment that can monitor and / or report on its operational status or other functions associated with its operation.

[0194] In practice, any number of UEs may be used together for a single use case. For example, a first UE may be a drone or integrated into a drone and provide drone speed information (obtained through a speed sensor) to a second UE that is a remote controller operating the drone. When a user makes changes from the remote controller, the first UE may adjust the drone's throttle (e.g., by controlling an actuator) to increase or decrease the drone's speed. The first and / or second UE may also include more than one of the above-described functionalities. For example, a UE may include a sensor and an actuator and handle communication of data for both the speed sensor and the actuator.

[0195] 16 illustrates a network node 1600 according to some embodiments. Examples of network nodes include, but are not limited to, access points (e.g., wireless access points) and base stations (e.g., wireless base stations, Node Bs, eNBs, and gNBs).

[0196] Base stations may be categorized based on the amount of coverage they provide (or, stated differently, their transmit power levels), and thus may be referred to as femto, pico, micro, or macro base stations, depending on the amount of coverage provided. A base station may also be a relay node or a relay donor node that controls a repeater. A network node may include one or more (or all) parts of a distributed radio base station, such as a centralized digital unit and / or a remote radio unit (RRU), sometimes also called a remote radio head (RRH). Such remote radio units may or may not be integrated with an antenna, such as an antenna-integrated radio. Some distributed radio base stations may also be referred to as nodes in a distributed antenna system (DAS).

[0197] Other examples of network nodes include multi-transmission point (multi-TRP) 5G access nodes, multi-standard radio (MSR) equipment such as an MSR BS, a network controller such as a radio network controller (RNC) or base station controller (BSC), a base transceiver station (BTS), a transmission point, a transmitting node, a multi-cell / multicast coordinating entity (MCE), an operations and maintenance (O&M) node, an operations support system (OSS) node, a self-organizing network (SON) node, a positioning node (e.g., an evolved serving mobile location center (E-SMLC) and / or a minimized drive test (MDT).

[0198] The network node 1600 includes a processing circuit 1602, a memory 1604, a communication interface 1606, and a power source 1608. The network node 1600 may be composed of multiple physically separate components (e.g., an NB component and an RNC component, or a BTS component and a BSC component, etc.), each of which may have its own respective components. In some scenarios in which the network node 1600 includes multiple separate components (e.g., a BTS and a BSC component), one or more of the separate components may be shared among several network nodes. For example, a single RNC may control multiple NBs. In such scenarios, each unique pair of NB and RNC may, in some examples, be considered a single separate network node. In some embodiments, the network node 1600 may be configured to support multiple radio access technologies (RATs). In such embodiments, some components may be redundant (e.g., separate memories 1604 for different RATs) and some components may be reused (e.g., the same antenna 1610 may be shared by different RATs). Network node 1600 may also include multiple sets of the various illustrated components for different wireless technologies, such as GSM, WCDMA, LTE, NR, WiFi, Zigbee, Z-wave, LoRaWAN, RFID (Radio Frequency Identification), or Bluetooth wireless technologies, that are integrated into network node 1600. The wireless technologies may be integrated into the same or different chips or sets of chips and other components within network node 1600.

[0199] The processing circuitry 1602 may include one or more combinations of a microprocessor, controller, microcontroller, central processing unit, digital signal processor, application specific integrated circuit, field programmable gate array, or other suitable computing device, resources, or combination of hardware, software, and / or coded logic operable, alone or in conjunction with other network node 1600 components, such as memory 1604, to provide the functionality of the network node 1600.

[0200] In some embodiments, the processing circuit 1602 comprises a system on a chip (SOC). In some embodiments, the processing circuit 1602 includes one or more of a radio frequency (RF) transceiver circuit 1612 and a baseband processing circuit 1614. In some embodiments, the RF transceiver circuit 1612 and the baseband processing circuit 1614 may be on separate chips (or set of chips), boards, or units, such as a radio unit and a digital unit. In alternative embodiments, some or all of the RF transceiver circuit 1612 and the baseband processing circuit 1614 may be on the same chip or set of chips, board, or unit.

[0201] The memory 1604 may include any form of volatile or non-volatile computer-readable memory, including, but not limited to, persistent storage, solid-state memory, remotely mounted memory, magnetic media, optical media, random access memory (RAM), read-only memory (ROM), mass storage media (e.g., hard disk), removable storage media (e.g., flash drive, compact disc (CD) or digital video disc (DVD)), and / or any other volatile or non-volatile non-transitory device-readable and / or computer-executable memory device that stores information, data, and / or instructions that can be used by the processing circuit 1602. The memory 1604 may store any suitable instructions, data, or information, including applications, including one or more of computer programs, software, logic, rules, code, tables, and / or other instructions, that are executable by the processing circuit 1602 and usable by the network node 1600 (collectively referred to as computer programs 1604a, which may be in the form of a computer program product). The memory 1604 may be used to store any computational results produced by the processing circuit 1602 and / or any data received via the interface 1606. In some embodiments, the processing circuit 1602 and the memory 1604 are integrated.

[0202] The communications interface 1606 is used for wired or wireless communication of signaling and / or data between network nodes, access networks, and / or UEs. As shown, the communications interface 1606 includes a port / terminal 1616 for transmitting and receiving data to and from a network, for example, over a wired connection. The communications interface 1606 also includes radio front-end circuitry 1618, which is coupled to an antenna 1610 or, in some embodiments, may be part of the antenna 1610. The radio front-end circuitry 1618 includes a filter 1620 and an amplifier 1622. The radio front-end circuitry 1618 may be connected to the antenna 1610 and the processing circuitry 1602. The radio front-end circuitry may be configured to condition signals communicated between the antenna 1610 and the processing circuitry 1602. The radio front-end circuitry 1618 may receive digital data to be sent to another network node or UE via a wireless connection. The radio front-end circuitry 1618 may convert the digital data into a radio signal having appropriate channel and bandwidth parameters using a combination of filters 1620 and / or amplifiers 1622. The radio signal may then be transmitted via the antenna 1610. Similarly, when data is received, the antenna 1610 collects the radio signal, which may then be converted into digital data by the radio front-end circuitry 1618. The digital data may be passed to the processing circuitry 1602. In other embodiments, the communication interface may include different components and / or different combinations of components.

[0203] In an alternative embodiment, the network node 1600 may not include a separate radio front-end circuit 1618; rather, the processing circuit 1602 may include the radio front-end circuitry and may be connected to the antenna 1610. Similarly, in some embodiments, all or some of the RF transceiver circuitry 1612 is part of the communications interface 1606. In yet another embodiment, the communications interface 1606 includes one or more ports or terminals 1616, the radio front-end circuitry 1618, and the RF transceiver circuitry 1612 as part of a radio unit (not shown), and the communications interface 1606 communicates with baseband processing circuitry 1614 that is part of a digital unit (not shown).

[0204] Antenna 1610 may include one or more antennas or antenna arrays configured to transmit and / or receive wireless signals. Antenna 1610 may be coupled to radio front-end circuitry 1618 and may be any type of antenna capable of transmitting and receiving data and / or signals wirelessly. In some embodiments, antenna 1610 is separate from network node 1600 and connectable to network node 1600 through an interface or port.

[0205] The antenna 1610, the communication interface 1606, and / or the processing circuit 1602 may be configured to perform any receiving operation and / or any obtaining operation described herein as being performed by a network node. Any information, data, and / or signals may be received from a UE, another network node, and / or any other network equipment. Similarly, the antenna 1610, the communication interface 1606, and / or the processing circuit 1602 may be configured to perform any transmitting operation described herein as being performed by a network node. Any information, data, and / or signals may be transmitted to a UE, another network node, and / or any other network equipment.

[0206] The power source 1608 provides power to the various components of the network node 1600 in a form appropriate for each component (e.g., at the voltage and current levels required for each component). The power source 1608 may include or be coupled to power management circuitry for providing power to the components of the network node 1600 to perform the functionality described herein. For example, the network node 1600 may be connectable to an external power source (e.g., a power grid, an electrical outlet) via an input circuit or interface, such as an electrical cable, whereby the external power source provides power to the power circuitry of the power source 1608. As a further example, the power source 1608 may include a power source in the form of a battery or battery pack connected to or integrated into the power circuitry. The battery may provide backup power in case of failure of the external power source.

[0207] Embodiments of network node 1600 may include additional components other than those shown in Figure 16 to provide certain aspects of the network node's functionality, including any of the functionality described herein and / or any functionality necessary to support the subject matter described herein. For example, network node 1600 may include user interface devices that allow information to be input into network node 1600 and information to be output from network node 1600. This may enable a user to perform diagnostic, maintenance, repair, and other administrative functions on network node 1600.

[0208] 17 is a block diagram of a host 1700, which may be an embodiment of the host 1416 of FIG. 14, in accordance with various aspects described herein. As used herein, the host 1700 may be or include various combinations of hardware and / or software, including a standalone server, a blade server, a cloud-implemented server, a distributed server, a virtual machine, a container, or processing resources within a server farm. The host 1700 may provide one or more services to one or more UEs.

[0209] Host 1700 includes a processing circuit 1702 operably coupled via bus 1704 to input / output interface 1706, a network interface 1708, a power supply 1710, and memory 1712. In other embodiments, other components may be included, the functionality of which may be substantially similar to those described with respect to the devices in previous figures, such as Figures 15 and 16, and therefore those descriptions are generally applicable to the corresponding components of host 1700.

[0210] Memory 1712 may include one or more computer programs, including one or more host application programs 1714, and data 1716, which may include user data, such as data generated by a UE for or by the host 1700 for a UE. An embodiment of the host 1700 may utilize only a subset or all of the illustrated components. The host application programs 1714 may be implemented in a container-based architecture and may provide support for video codecs (e.g., Versatile Video Coding (VVC), High Efficiency Video Coding (HEVC), Advanced Video Coding (AVC), MPEG, VP9) and audio codecs (e.g., FLAC, Advanced Audio Coding (AAC), MPEG, G.711), including transcoding for different UE classes, types, or implementations (e.g., handsets, desktop computers, wearable display systems, heads-up display systems). The host application program 1714 may also provide user authentication and license checks, and may periodically report health, route, and content availability to a central node, such as a device in or at the edge of the core network. Thus, the host 1700 may select and / or point to different hosts for over-the-top services for the UE. The host application program 1714 may support a variety of protocols, such as HTTP Live Streaming (HLS) protocol, Real-Time Messaging Protocol (RTMP), Real-Time Streaming Protocol (RTSP), Dynamic Adaptive Streaming over HTTP (MPEG-DASH), etc.

[0211] FIG. 18 is a block diagram illustrating a virtualization environment 1800 in which functionality implemented according to some embodiments may be virtualized. In this context, virtualization means for creating a virtual version of an apparatus or device may include a virtualized hardware platform, storage devices, and networking resources. As used herein, virtualization may apply to any device or component thereof described herein and refer to an implementation in which at least a portion of its functionality is implemented as one or more virtual components. Some or all of the functionality described herein may be implemented as virtual components executed by one or more virtual machines (VMs) implemented within one or more virtual environments 1800 hosted by one or more hardware nodes, such as a network node, a UE, a core network node, or a hardware computing device acting as a host. Furthermore, in embodiments in which a virtualized node does not require wireless connectivity (e.g., a core network node or host), the node may be virtualized in its entirety.

[0212] An application 1802 (which may alternatively be referred to as a software instance, a virtual appliance, a network function, a virtual node, a virtual network function, etc.) runs in the virtualized environment 1800 to implement some of the features, functionality and / or benefits of some of the embodiments disclosed herein.

[0213] The hardware 1804 may include processing circuitry, memory for storing software and / or instructions executable by the processing circuitry (collectively referred to as computer program 1604a, which may be in the form of a computer program product), and / or hardware devices as described herein, such as network interfaces and input / output interfaces. The software is executed by the processing circuitry to instantiate one or more virtualization layers 1806 (also referred to as hypervisors or virtual machine monitors (VMMs)), provide VMs 1808a-b (one or more of which may be collectively referred to as VMs 1808), and / or perform any of the functions, features, and / or benefits described in connection with some embodiments described herein. The virtualization layer 1806 may present a virtual operating platform that appears to the virtual machines 1808 as networking hardware.

[0214] The VMs 1808 may include virtual processing, virtual memory, virtual networking or interfaces, and virtual storage, and may be executed by a corresponding virtualization layer 1806. Various embodiments of virtual appliances 1802 may be implemented in one or more of the VMs 1808, and the implementation may be done in various ways. Hardware virtualization is referred to in some contexts as network functions virtualization (NFV). NFV may be used to aggregate many network equipment types into industry-standard, high-capacity server hardware, physical switches, and physical storage that may be located in data centers and customer premises equipment.

[0215] In the context of NFV, each VM 1808 may be a software implementation of a physical machine that runs programs as if they were running on a physical, non-virtualized machine. Each VM 1808 and the portion of hardware 1804 on which it runs, whether the hardware is dedicated to that VM and / or shared by that VM with other VMs, forms a separate virtual network element. Also in the context of NFV, a virtual network function is responsible for handling specific network functions running in one or more VMs 1808 on top of the hardware 1804 and corresponds to the application 1802.

[0216] The hardware 1804 may be implemented in a standalone network node with generic or proprietary components. The hardware 1804 may implement some functions via virtualization. Alternatively, the hardware 1804 may be part of a larger hardware cluster (e.g., in a data center or CPE) where multiple hardware nodes cooperate and are managed via management and orchestration 1810, which oversees, among other things, the lifecycle management of the application 1802. In some embodiments, the hardware 1804 is coupled to one or more radio units, each including one or more transmitters and one or more receivers, which may be coupled to one or more antennas. The radio units may communicate directly with other hardware nodes via one or more appropriate network interfaces or may be used in combination with virtual components, such as radio access nodes or base stations, to provide wireless capabilities to virtual nodes. In some embodiments, some signaling may be provided with the use of a control system 1812, which may alternatively be used for communication between the hardware nodes and the radio units.

[0217] Figure 19 shows a communication diagram of a host 1902 communicating with a UE 1906 via a network node 1904 over a partially wireless connection, according to some embodiments. Exemplary implementations, according to various embodiments, of the UE (UE 1412a of Figure 14 and / or UE 1500 of Figure 15), network node (network node 1410a of Figure 14 and / or network node 1600 of Figure 16), and host (host 1416 of Figure 14 and / or host 1700 of Figure 17) discussed in the previous paragraphs will now be described with reference to Figure 19.

[0218] Similar to the host 1700, an embodiment of the host 1902 includes hardware such as a communications interface, processing circuitry, and memory. The host 1902 also includes software stored within or accessible by the host 1902 and executable by the processing circuitry. The software includes a host application that may be operable to provide services to a remote user, such as a UE 1906, connecting via an over-the-top (OTT) connection 1950 extending between the UE 1906 and the host 1902. During the provision of services to the remote user, the host application may provide user data that is transmitted using the OTT connection 1950.

[0219] The network node 1904 includes hardware that enables communication with the host 1902 and the UE 1906. The connection 1960 may be direct or may pass through one or more other intermediate networks, such as a core network (such as the core network 1406 of FIG. 14) and / or one or more public, private, or hosted networks. For example, the intermediate network may be a backbone network or the Internet.

[0220] The UE 1906 also includes software stored within or accessible by the UE 1906 and executable by the UE's processing circuitry. This software includes client applications, such as a web browser or operator-specific "apps," that, with the support of the host 1902, may be operable to provide services to a human or non-human user via the UE 1906. Host applications running on the host 1902 may communicate with client applications running on the host 1902 via an OTT connection 1950 that terminates at the UE 1906 and the host 1902. During the provision of services to the user, the client applications on the UE may receive request data from the host applications on the host and provide user data in response to the request data. The OTT connection 1950 may transport both the request data and user data. The client applications on the UE may interact with the user to generate user data that they provide to the host applications over the OTT connection 1950.

[0221] The OTT connection 1950 may extend via a connection 1960 between the host 1902 and the network node 1904 and via a wireless connection 1970 between the network node 1904 and the UE 1906, providing connectivity between the host 1902 and the UE 1906. The connection 1960 and the wireless connection 1970 over which the OTT connection 1950 may be provided are depicted abstractly to illustrate communication between the host 1902 and the UE 1906 via the network node 1904 without explicit reference to any intermediate devices and the precise routing of messages through those devices.

[0222] As an example of transmitting data over the OTT connection 1950, in step 1908, the host 1902 provides user data, which may be done by executing a host application. In some embodiments, the user data is associated with a specific human user interacting with the UE 1906. In other embodiments, the user data is associated with the UE 1906 sharing data with the host 1902 without explicit human interaction. In step 1910, the host 1902 initiates a transmission to the UE 1906 carrying user data. The host 1902 may initiate the transmission in response to a request sent by the UE 1906. The request may be triggered by human interaction with the UE 1906 or by the operation of a client application running on the UE 1906. The transmission may pass through the network node 1904 in accordance with the teachings of embodiments described throughout this disclosure. In response, at step 1912, the network node 1904 transmits the user data carried in the transmission initiated by the host 1902 to the UE 1906, in accordance with the teachings of embodiments described throughout this disclosure. At step 1914, the UE 1906 receives the user data carried in the transmission, which may be done by a client application running on the UE 1906 that is associated with a host application executed by the host 1902.

[0223] In some examples, the UE 1906 executes a client application, which provides user data destined for the host 1902. The user data may be provided in reaction or response to receiving the data from the host 1902. In response, the UE 1906 may provide the user data at step 1916, which may be done by executing the client application. During the provision of the user data, the client application may further consider user input received from a user via an input / output interface of the UE 1906. Regardless of the specific manner in which the user data is provided, the UE 1906 initiates transmission of the user data to the host 1902 via the network node 1904 at step 1918. At step 1920, in accordance with the teachings of embodiments described throughout this disclosure, the network node 1904 receives the user data from the UE 1906 and initiates transmission of the received user data to the host 1902. At step 1922, the host 1902 receives the user data carried in the transmission initiated by the UE 1906.

[0224] One or more of the various embodiments improve the performance of the OTT service provided to the UE 1906 using the OTT connection 1950, in which the radio connection 1970 forms the final leg. More precisely, the embodiments described herein can facilitate much faster execution of L1 / L2 inter-cell mobility compared to existing L3-based inter-cell mobility because the execution phase is separated from the preparation phase, and as a result, the timing of the lower layer signaling that triggers the execution of L1 / L2 inter-cell mobility is at the discretion of the source DU. These advantages are made possible by providing the UE with a TCI state ID or SSB index for a candidate cell in the lower layer signaling that triggers the execution of L1 / L2 inter-cell mobility, which facilitates timely UE communication with the candidate cell. Furthermore, by providing the UE with an indication of whether the UE should perform a MAC reset in conjunction with L1 / L2 inter-cell mobility, the embodiments avoid data loss and unnecessary interruptions in cases where a MAC reset is unnecessary. Broadly speaking, the embodiments improve mobility in a RAN (e.g., NG-RAN). By improving UE and RAN operation in this manner, embodiments enhance the value of OTT services delivered to / from UEs via the RAN.

[0225] In an exemplary scenario, factory status information may be collected and analyzed by the host 1902. As another example, the host 1902 may process audio and video data, possibly obtained from UEs, for use in generating maps. As another example, the host 1902 may collect and analyze real-time data to assist in traffic congestion control (e.g., traffic light control). As another example, the host 1902 may store surveillance video uploaded by UEs. As another example, the host 1902 may store or control access to media content, such as video, audio, VR, or AR, that may be broadcast, multicast, or unicast to UEs. As another example, the host 1902 may be used for energy pricing, remote control of non-time-critical power loads for balancing power generation needs, location services, presentation services (e.g., compiling diagrams from data collected from remote devices), or any other function that collects, acquires, stores, analyzes, and / or transmits data.

[0226] In some examples, measurement procedures may be provided to monitor data rates, latency, and other factors that may be improved by one or more embodiments. There may also be optional network functionality for reconfiguring the OTT connection 1950 between the host 1902 and the UE 1906 in response to fluctuations in the measurements. The measurement procedures and / or network functionality for reconfiguring the OTT connection may be implemented in software and hardware in the host 1902 and / or the UE 1906. In some embodiments, sensors (not shown) may be deployed in or associated with other devices through which the OTT connection 1950 passes, and these sensors may participate in the measurement procedures by providing values ​​for the monitored quantities exemplified above or other physical quantities from which the monitored quantities may be calculated or estimated by software. Reconfiguration of the OTT connection 1950 may include message formats, retransmission settings, preferred routing, etc., and the reconfiguration need not directly change the operation of the network node 1904. Such procedures and functionality may be known and practiced in the art. In one embodiment, the measurements may involve proprietary UE signaling that facilitates measurements of throughput, propagation time, latency, etc. by the host 1902. The measurements may be performed by sending messages (particularly empty or "dummy" messages) using the OTT connection 1950 while software monitors propagation times, errors, etc.

[0227] The foregoing merely illustrates the principles of the present disclosure. Various modifications and alterations to the described embodiments will be apparent to those skilled in the art in light of the teachings herein. It will thus be appreciated that those skilled in the art will be able to devise numerous systems, configurations, and procedures that, although not explicitly shown or described herein, embody the principles of the present disclosure and thus may be within the spirit and scope of the present disclosure. As will be understood by those skilled in the art, the various embodiments can be used in conjunction with, and interchangeably with, one another.

[0228] The term unit as used herein may have its conventional meaning in the field of electronic equipment, electrical devices, and / or electronic devices, and may include, for example, electric and / or electronic circuits, devices, modules, processors, memories, logic solid state and / or discrete devices, computer programs, or instructions for performing respective tasks, procedures, operations, output, and / or display functions, etc., such as those described herein.

[0229] Any suitable step, method, feature, function, or benefit disclosed herein may be performed via one or more functional units or modules of one or more virtual devices. Each virtual device may comprise several of these functional units. These functional units may be implemented via processing circuitry, which may include one or more microprocessors or microcontrollers, and other digital hardware, which may include digital signal processors (DSPs), dedicated digital logic, and the like. The processing circuitry is configurable to execute program code stored in memory, which may include one or more types of memory, such as read-only memory (ROM), random access memory (RAM), cache memory, flash memory devices, optical storage devices, etc. The program code stored in memory includes program instructions for implementing one or more communication and / or data communication protocols, as well as instructions for executing one or more of the techniques described herein. In some implementations, the processing circuitry may be used to cause each functional unit to perform corresponding functions according to one or more embodiments of the present disclosure.

[0230] As described herein, a device and / or apparatus may be represented by a semiconductor chip, chipset, or (hardware) module comprising such a chip or chipset, without excluding the functionality of the device or apparatus, which may instead be implemented in hardware as a software module, such as a computer program or computer program product comprising executable software code portions executed or running on a processor. Furthermore, the functionality of a device or apparatus may be implemented by any combination of hardware and software. A device or apparatus may further be considered an assembly of multiple devices and / or apparatus, whether functionally cooperating with each other or independent of each other. Furthermore, devices and apparatus may be implemented in a distributed manner throughout a system, so long as the functionality of the device or apparatus is maintained. Such and similar principles are believed to be known to those skilled in the art.

[0231] Furthermore, functionality described herein as being performed by a wireless device or network node may be distributed across multiple wireless devices and / or network nodes. In other words, it is contemplated that the functionality of the network nodes and wireless devices described herein is not limited to performance by a single physical device, but may in fact be distributed among several physical devices.

[0232] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. Terms used herein should be interpreted to have a meaning consistent with their meaning in the context of the present specification and related art, and will be further understood not to be interpreted in an idealized or overly formal sense unless explicitly defined herein.

[0233] Additionally, certain terms used in this disclosure, including the specification and drawings, may be used synonymously in certain instances (e.g., "data" and "information"). Although these terms (and / or other terms that may be synonymous with each other) may be used synonymously herein, it is understood that there may be cases where it is intended that such terms not be used synonymously.

[0234] The techniques and devices described herein include, but are not limited to, the examples listed below: A1. A method for a user equipment (UE) configured to communicate with a radio access network (RAN) node having a central unit (CU) and a distributed unit (DU) that provides a serving cell for the UE, the method comprising: receiving a lower layer signaling message from the DU indicating that the UE should perform L1 / L2-based inter-cell mobility to a first candidate cell provided by the candidate DU, where the lower layer signaling message includes: an indicator or identity of the first candidate cell; and an indication of a first transmission configuration indicator (TCI) state to be used by the UE to communicate with the first candidate cell; performing an L1 / L2 mobility procedure toward the first candidate cell; and communicating in the first candidate cell based on the first TCI state; It has.

[0235] A2. The method of embodiment A1, wherein the indication of the first TCI state is a TCI state identifier.

[0236] A3. The method of embodiment A1, wherein the indication of the first TCI state is an index of a first beam or reference signal (RS) transmitted in the first candidate cell.

[0237] A4. The method of embodiment A3, further comprising: receiving an RRCReconfiguration message from the CU via the DU, the RRCReconfiguration message including configurations associated with one or more candidate cells for L1 / L2-based inter-cell mobility, including the first candidate cell; and Each candidate cell configuration includes multiple TCI state configurations; Each TCI state configuration includes an index of a beam or RS configured as a quasi-colocated (QCL) source; selecting one of the TCI state configurations including the index of the first beam or RS as a QCL source as the first TCI state; It has.

[0238] A5. The method of embodiment A4, further comprising sending an RRCReconfigurationComplete message to the CU via the DU in response to the RRCReconfiguration message.

[0239] A5a. A method according to any one of embodiments A4 to A5, wherein the configuration for the first candidate cell includes an indication of whether the UE should perform a medium access control (MAC) reset when performing the L1 / L2 inter-cell mobility to the first candidate cell.

[0240] A6. The method of any of embodiments A1-A5a, further comprising: performing measurements on a plurality of beams or reference signals (RS) transmitted in the first candidate cell; and transmitting results of the measurement to the DU; Here, the first TCI state corresponds to the index of the beam or RS having the most favorable measurement result for L1 / L2 mobility to the first candidate cell.

[0241] A6a. The method of embodiment A6, wherein the plurality of beams or RSs include one or more of a synchronization signal / PBCH block (SSB) and a channel state information reference signal (CSI-RS).

[0242] A7. The method of any one of embodiments A1-A6, wherein the lower layer signaling message further includes one or more of the following: an indication of whether the UE should perform a random access (RA) procedure when performing L1 / L2 inter-cell mobility to the first candidate cell; and An indication of whether the UE should perform a Medium Access Control (MAC) reset when performing L1 / L2 inter-cell mobility to the first candidate cell.

[0243] A8. The method of embodiment A7, wherein performing the L1 / L2 mobility procedure toward the first candidate cell comprises selectively performing one or more of the following operations based on the indication of whether the UE should perform a MAC reset: initializing MAC state variables; Stopping, starting, or restarting a MAC timer; resetting a new data indicator (NDI) for an uplink hybrid ARQ process to zero; and Stopping any MAC procedure in progress; and canceling MAC procedures that have been triggered but are not in progress; Flushing the MAC message buffer; Resetting the MAC counter; Releasing a Radio Network Temporary Identifier (RNTI) assigned to the UE.

[0244] A9. The method of any of embodiments A7-A8, wherein performing the L1 / L2 mobility procedure toward the first candidate cell comprises selectively performing an RA procedure in the first candidate cell based on one or more of the following: the indication of whether the UE should perform an RA procedure; and whether the time alignment of the first candidate cell is different from the time alignment of the serving cell; and whether a time alignment timer of the first candidate cell has expired; Whether the time alignment of said first candidate cell is known or unknown.

[0245] A10. The method of any of embodiments A1-A9, wherein one or more of the following apply: the lower layer signaling message is for a protocol layer below a radio resource control (RRC) protocol layer; and The lower layer signaling message is one of a MAC Control Element (MAC CE) or a PHY Downlink Control Information (DCI).

[0246] A11. The method of any of embodiments A1-A10, wherein communicating in the first candidate cell based on the first TCI state includes one or more of the following: monitoring a downlink control channel of the first candidate cell in a beam or spatial direction corresponding to the first TCI state; Transmitting uplink data or a scheduling request to the first candidate cell in a beam or spatial direction corresponding to the first TCI state.

[0247] A12. The method of any of embodiments A1-A11, wherein the candidate DU is associated with the CU and / or is part of the RAN node.

[0248] B1. A method for a distributed unit (DU) of a radio access network (RAN) node, the DU coupled to a central unit (CU) of the RAN node and configured to provide a serving cell for a user equipment (UE), the method comprising: selecting a first candidate cell provided by a candidate DU for L1 / L2-based inter-cell mobility of a UE currently served by the DU via the serving cell; sending, to the UE, a lower layer signaling message indicating that the UE should perform L1 / L2-based inter-cell mobility to the first candidate cell, wherein the lower layer signaling message comprises: an indicator or identity of the first candidate cell; and and an indication of a first transmission configuration indicator (TCI) state to be used by the UE to communicate with the first candidate cell.

[0249] B2. The method of any one of embodiments A1 to A5a, further comprising receiving from the UE results of measurements performed by the UE on a plurality of beams or reference signals (RSs) transmitted in the first candidate cell, wherein the measurement results include respective indices of the plurality of beams or RSs.

[0250] B2a. The method of embodiment B2, wherein the plurality of beams or RSs include one or more of a synchronization signal / PBCH block (SSB) and a channel state information reference signal (CSI-RS).

[0251] B3. The method of any of embodiments B2-B2a, wherein the first TCI state is associated with a first beam or RS having a measurement result that is most favorable for L1 / L2 mobility to the first candidate cell.

[0252] B4. The method of embodiment B3, wherein the indication of the first TCI state is the index of the first beam or RS.

[0253] B5. The method of embodiment B3, wherein the indication of the first TCI state is a TCI state identifier.

[0254] B6. The method of embodiment B5, further comprising: determining the TCI state identifier for the first TCI state based on the index of the first beam or RS and a mapping between a TCI state identifier used in the first candidate cell and an index of a beam or RS transmitted in the first candidate cell.

[0255] B7. The method of embodiment B6, further comprising receiving the mapping from one of the candidate DUs or the CUs.

[0256] B8. The method of any of embodiments B1-B7, further comprising sending a message to the CU or to the candidate DU, the message including one or more of the following: an indicator or identity of the first candidate cell for L1 / L2 based inter-cell mobility of the UE; An indication of the first TCI state to be used by the UE to communicate with the first candidate cell and a copy or encapsulation of the lower layer signaling message.

[0257] B9. The method of any of embodiments B1-B8, wherein the lower layer signaling message further includes one or more of the following: an indication of whether the UE should perform a random access (RA) procedure when performing L1 / L2 inter-cell mobility to the first candidate cell; and An indication of whether the UE should perform a medium access control (MAC) reset when performing the L1 / L2 inter-cell mobility to the first candidate cell.

[0258] B10. The method of embodiment B9, further comprising, when performing L1 / L2 inter-cell mobility to the first candidate cell as indicated in the lower layer signaling message, determining whether the UE should perform an RA procedure based on one or more of the following: whether the time alignment of the first candidate cell is different from the time alignment of the serving cell; and whether a time alignment timer of the first candidate cell has expired; Whether the time alignment of said first candidate cell is known or unknown.

[0259] B11. The method of any of embodiments B1-B10, wherein one or more of the following apply: the lower layer signaling message is for a protocol layer below a radio resource control (RRC) protocol layer; and The lower layer signaling message is a MAC Control Element (MAC CE) or a PHY Downlink Control Information (DCI).

[0260] B12. The method of any of embodiments B1-B11, wherein the candidate DU is associated with the CU and / or is part of the RAN node.

[0261] B13. The method of any one of embodiments B1-B12, further comprising: sending a request to the CU or to the candidate DU to configure the UE with at least one candidate cell for L1 / L2-based inter-cell mobility; receiving, from the CU or the candidate DU, configurations for one or more candidate cells provided by the candidate DU, including the first candidate cell; sending the configuration to the UE in an RRCReconfiguration message; It has.

[0262] C1. A method for a candidate distributed unit (DU) of a radio access network (RAN) node, the candidate DU being coupled to a central unit (CU) of the RAN node, the method comprising: receiving a request from the CU or from the DU currently serving the UE via a serving cell to configure the UE with at least one candidate cell for L1 / L2-based inter-cell mobility; transmitting to the CU or the DU configurations for one or more candidate cells provided by the candidate DU, including the first candidate cell; receiving a message from the DU indicating an L1 / L2 mobility procedure by the UE, where the message comprises: an indicator or identity of the first candidate cell for L1 / L2 based inter-cell mobility of the UE; an indication of a first transmission configuration indicator (TCI) state to be used by the UE to communicate with the first candidate cell; and communicating with the UE in the first candidate cell based on the first TCI state.

[0263] C2. A method as described in embodiment C1, wherein the indicator or identification information of the first candidate cell and the indication of the first TCI state are received in a copy or encapsulated version of a lower layer signaling message sent by the DU to the UE.

[0264] C3. The method of any one of embodiments C1-C2, wherein the indication of the first TCI state is an index of a first beam or reference signal (RS) transmitted in the candidate cell.

[0265] C4. The method of embodiment C3, further comprising determining the first TCI state or its identifier based on the index of the first beam or RS and a mapping between a TCI state identifier used in the first candidate cell and an index of a beam or RS transmitted in the first candidate cell.

[0266] C5. The method of any of embodiments C1-C2, comprising: The first TCI state indication is a TCI state identifier, and the method further comprises: The method includes transmitting to the CU or the DU a mapping between a TCI status identifier used in the first candidate cell and an index of a beam or RS transmitted in the first candidate cell.

[0267] C6. A method according to any one of embodiments C1 to C5, wherein the configuration of the first candidate cell includes an indication of whether the UE should perform a medium access control (MAC) reset when performing the L1 / L2 inter-cell mobility to the first candidate cell.

[0268] C7. The method of any of embodiments C1-C6, wherein communicating with the UE in the first candidate cell based on the first TCI state includes one or more of the following: Transmitting a control channel of the first candidate cell in a beam or spatial direction corresponding to the first TCI; Receiving uplink data or a scheduling request from the UE in the first candidate cell in a beam or spatial direction corresponding to the first TCI state.

[0269] C8. The method of any of embodiments C1-C7, wherein the DU is associated with the CU and / or is part of the RAN node.

[0270] D1. A user equipment (UE) configured to provide a serving cell for the UE and to communicate with a radio access network (RAN) node including a central unit (CU) and a distributed unit (DU), the UE comprising: a communication interface circuit configured to communicate with the CU and at least the DU; and a processing circuit operably coupled to the communication interface circuit, wherein the processing circuit and the communication interface circuit are further configured to perform operations corresponding to the method described in any one of embodiments A1 to A12.

[0271] D2. A user equipment (UE) configured to communicate with a radio access network (RAN) node having a central unit (CU) and a distributed unit (DU) that provides a serving cell for the UE, wherein the UE is further configured to perform operations corresponding to a method described in any of embodiments A1 to A12.

[0272] D3. A non-transitory computer-readable medium storing computer-executable instructions that, when executed by processing circuitry of a user equipment (UE), the UE having a central unit (CU) and a distributed unit (DU) and configured to communicate with a radio access network (RAN) node that provides a serving cell for the UE, configure the UE to perform operations corresponding to the method of any of embodiments A1-A12.

[0273] D4. A computer program product including computer-executable instructions, which, when executed by processing circuitry of a user equipment (UE) configured to communicate with a radio access network (RAN) node having a central unit (CU) and a distributed unit (DU) that provides a serving cell for the UE, configure the UE to perform operations corresponding to the method described in any of embodiments A1-A12.

[0274] E1. A distributed unit (DU) of a radio access network (RAN) node, the DU coupled to a central unit (CU) of the RAN node and configured to provide a serving cell for a user equipment (UE), the DU comprising: a communication interface circuit configured to communicate with the CU and the UE; and a processing circuit operably coupled to the communication interface circuit, whereby the processing circuit and the communication interface circuit are configured to perform operations corresponding to the method described in any of embodiments B1 to B13.

[0275] E2. A distributed unit (DU) of a radio access network (RAN) node, the DU coupled to a central unit (CU) of the RAN node and configured to provide a serving cell to a user equipment (UE), the DU further configured to perform operations corresponding to a method described in any of embodiments B1 to B13.

[0276] E3. A non-transitory computer-readable medium storing computer-executable instructions that, when executed by processing circuitry of a distributed unit (DU) coupled to a central unit (CU) of a radio access network (RAN) node and configured to provide a serving cell to a user equipment (UE), configure the DU to perform operations corresponding to the method of any of embodiments B1-B13.

[0277] E4. A computer program product having computer-executable instructions that, when executed by processing circuitry of a distributed unit (DU) coupled to a central unit (CU) of a radio access network (RAN) node and configured to provide a serving cell to a user equipment (UE), configure the DU to perform operations corresponding to the method of any of embodiments B1-B13.

[0278] F1. A candidate distributed unit (DU) of a radio access network (RAN) node, the candidate DU coupled to a central unit (CU) of the RAN node, the candidate DU comprising: a communication interface circuit configured to communicate with the CU and to communicate with the UE via one or more cells provided by the candidate DU; and a processing circuit operably coupled to the communication interface circuit, whereby the processing circuit and the communication interface circuit are configured to perform operations corresponding to the method described in any of embodiments C1 to C8.

[0279] F2. A second distributed unit (DU) of a radio access network (RAN) node, coupled to a centralized unit (CU) of the RAN node, the second DU configured to perform operations corresponding to the method described in any of embodiments C1 to C8.

[0280] F3. A non-transitory computer-readable medium storing computer-executable instructions that, when executed by processing circuitry of a candidate distributed unit (DU) coupled to a central unit (CU) of a radio access network (RAN) node, configure the candidate DU to perform operations corresponding to the method of any of embodiments C1-C8.

[0281] F4. A computer program product having computer-executable instructions that, when executed by processing circuitry of a candidate distributed unit (DU) coupled to a central unit (CU) of a radio access network (RAN) node, configures the candidate DU to perform operations corresponding to the method of any of embodiments C1-C8.

Claims

1. 1. A method for a user equipment (UE) configured to communicate with a radio access network (RAN) node having a central unit (CU) and a distributed unit (DU) providing a serving cell for the UE, the method comprising: receiving 1150 a lower layer signaling message from the DU indicating that the UE should perform L1 / L2-based inter-cell mobility to a first candidate cell served by the candidate DU, wherein the lower layer signaling message includes: an indicator or identity of the first candidate cell; and an indication of a first transmission configuration indicator (TCI) state to be used by the UE to communicate with the first candidate cell; performing an L1 / L2 mobility procedure toward the first candidate cell (1170); and communicating in the first candidate cell based on the first TCI state; A method having the following.

2. 2. The method of claim 1, wherein the indication of the first TCI state is one of a TCI state identifier or an index of a first beam or reference signal transmitted in the first candidate cell.

3. 3. The method of claim 2, further comprising: receiving 1110 an RRCReconfiguration message from the CU via the DU, the RRCReconfiguration message including configurations associated with one or more candidate cells for L1 / L2-based inter-cell mobility, including the first candidate cell; Each candidate cell configuration includes multiple TCI state configurations; Each TCI state configuration includes an index of a beam or RS arranged as a quasi-collocated (QCL) source; selecting 1160 as the first TCI state one of the TCI state configurations that includes the index of the first beam or RS that is a QCL source; A method having the following.

4. 4. The method of claim 3, further comprising: sending (1120) an RRCReconfigurationComplete message to the CU via the DU in response to the RRCReconfiguration message.

5. 5. The method of claim 3, wherein one of the configuration for the first candidate cell or the lower layer signaling message includes an indication of whether to perform a medium access control (MAC) reset when the UE performs the L1 / L2 inter-cell mobility to the first candidate cell.

6. 6. The method of claim 5, wherein performing (1170) the L1 / L2 mobility procedure towards the first candidate cell comprises selectively performing (1171) one or more of the following actions based on the indication of whether the UE should perform a MAC reset: initializing MAC state variables; Stopping, starting, or restarting a MAC timer; resetting a new data indicator (NDI) of the uplink hybrid ARQ process to zero; Stopping an ongoing MAC procedure; Canceling a MAC procedure that has been triggered but is not in progress; Flushing the MAC message buffer; resetting the MAC counter; Releasing a Radio Network Temporary Identifier (RNTI) assigned to the UE; That's the method.

7. 7. The method according to claim 1, wherein the lower layer signaling message further includes an indication of whether the UE should perform a random access (RA) procedure when performing L1 / L2 inter-cell mobility to the first candidate cell.

8. 10. The method of claim 7, wherein performing (1170) the L1 / L2 mobility procedure towards the first candidate cell comprises selectively performing (1172) an RA procedure in the first candidate cell based on one or more of the following: an indication of whether the UE should perform an RA procedure; and whether the time alignment of the first candidate cell is different from the time alignment of the serving cell; whether a time alignment timer of the first candidate cell has expired; whether the time alignment of the first candidate cell is known or unknown; That's the method.

9. The method according to any one of claims 1 to 8, further comprising: performing 1130 measurements on a plurality of beams or reference signals (RS) transmitted in the first candidate cell; and transmitting (1140) results of the measurements to the DU; A method wherein the first TCI state corresponds to an index of a beam or RS having a most favorable measurement result for L1 / L2 mobility to the first candidate cell.

10. 10. The method of claim 9, wherein the plurality of beams or RSs include one or more of: synchronization signals / PBCH blocks (SSBs) and channel state information reference signals (CSI-RSs).

11. The method according to any one of claims 1 to 10, the lower layer signaling message is for a protocol layer below a Radio Resource Control (RRC) protocol layer; and the lower layer signaling message is one of a Medium Access Control (MAC) Control Element (CE) or a physical layer Downlink Control Information (DCI); The method according to claim 1, wherein one or more of the following is applied:

12. 12. The method of claim 1, wherein communicating in the first candidate cell based on the first TCI state (1170) comprises: monitoring 1173 a downlink control channel of the first candidate cell in a beam or spatial direction corresponding to the first TCI state; transmitting 1174 uplink data or a scheduling request to the first candidate cell in a beam or spatial direction corresponding to the first TCI state; A method comprising one or more of:

13. The method according to any one of claims 1 to 12, wherein the candidate DU is associated with the CU and / or is part of the RAN node.

14. 1. A method for a distributed unit (DU) of a radio access network (RAN) node, the DU configured to communicate with a central unit (CU) of the RAN node and provide a serving cell to a user equipment (UE), the method comprising: selecting (1250) a first candidate cell provided by a candidate DU for L1 / L2-based inter-cell mobility of a UE served by the DU via the serving cell; sending 1280 a lower layer signaling message to the UE indicating that the UE should perform L1 / L2-based inter-cell mobility to the first candidate cell; wherein the lower layer signaling message is an indicator or identity of the first candidate cell; and an indication of a first transmission configuration indicator (TCI) state to be used by the UE to communicate with the first candidate cell; and A method comprising:

15. 15. The method of claim 14, further comprising receiving (1240) from the UE results of measurements performed by the UE on a plurality of beams or reference signals (RSs) transmitted in the first candidate cell, the results of the measurements including respective indices of the plurality of beams or RSs.

16. 16. The method of claim 15, wherein the plurality of beams or RSs include one or more of a synchronization signal / PBCH block (SSB) and a channel state information reference signal (CSI-RS).

17. A method according to any one of claims 15 to 16, wherein the first TCI state is associated with a first beam or RS having measurement results that are most favorable for L1 / L2 mobility to the first candidate cell.

18. 18. The method of claim 17, wherein the indication of the first TCI state is one of the index of the first beam or RS, or a TCI state identifier.

19. 20. The method of claim 18, further comprising determining (1260) the TCI state identifier for the first TCI state based on: the index of the first beam or RS, which is the indication of the first TCI state; and A mapping between a TCI state identifier used in the first candidate cell and an index of a beam or RS transmitted in the first candidate cell.

20. 20. The method of claim 19, further comprising receiving (1205) the mapping from the candidate DU or the CU.

21. The method according to any one of claims 14 to 20, further comprising sending (1290) a message to the CU or the candidate DU, wherein the message comprises: the indicator or identity of the first candidate cell for L1 / L2 based inter-cell mobility of the UE; and the indication of the first TCI state to be used by the UE to communicate with the first candidate cell; and a copy or encapsulation of said lower layer signaling message; A method comprising one or more of:

22. 22. The method according to claim 14, wherein the lower layer signaling message further comprises: an indication of whether the UE should perform a random access (RA) procedure when performing L1 / L2 inter-cell mobility to the first candidate cell; and an indication of whether to perform a Medium Access Control (MAC) reset when the UE performs the L1 / L2 inter-cell mobility to the first candidate cell; and A method comprising one or more of:

23. 23. The method of claim 22, further comprising: determining (1270) whether the UE should perform an RA procedure when performing L1 / L2 inter-cell mobility to the first candidate cell as indicated in the lower layer signaling message based on one or more of the following: whether the time alignment of the first candidate cell is different from the time alignment of the serving cell; whether a time alignment timer of the first candidate cell has expired; whether the time alignment of the first candidate cell is known or unknown; That's the method.

24. The method according to any one of claims 14 to 23, the lower layer signaling message is for a protocol layer below a Radio Resource Control (RRC) protocol layer; the lower layer signaling message is one of a Medium Access Control (MAC) Control Element (CE) or a physical layer Downlink Control Information (DCI); The method according to claim 1, wherein one or more of the following is applied:

25. The method according to any one of claims 14 to 24. The method, wherein the candidate DU is associated with the CU and / or is part of the RAN node.

26. The method according to any one of claims 14 to 25, further comprising: sending a request to the CU or the candidate DU to configure the UE with at least one candidate cell for L1 / L2-based inter-cell mobility (1210); receiving, from the CU or the candidate DU, configurations for one or more candidate cells provided by the candidate DU, including the first candidate cell (1220); sending (1230) said configuration to said UE in an RRCReconfiguration message; , a method having

27. 1. A method for a candidate distributed unit (DU) of a radio access network (RAN) node, the candidate DU configured to communicate with a central unit (CU) of the RAN node, the method comprising: receiving a request from the CU or from a DU serving the UE via a serving cell to configure the UE with at least one candidate cell for L1 / L2-based inter-cell mobility (1320); transmitting to the CU or the DU configurations for one or more candidate cells provided by the candidate DU, including a first candidate cell (1330); receiving 1340 a message from the DU indicating an L1 / L2 mobility procedure by the UE, wherein the message comprises: an indicator or identity of the first candidate cell for L1 / L2 based inter-cell mobility of the UE; and an indication of a first transmission configuration indicator (TCI) state to be used by the UE to communicate with the first candidate cell; communicating with the UE in the first candidate cell based on the first TCI state (1360); A method having the following.

28. 28. The method of claim 27, wherein the indicator or identification information of the first candidate cell and the indication of the first TCI state are received in a copy or encapsulated version of a lower layer signaling message sent by the DU to the UE.

29. The method according to any one of claims 27 to 28, the indication of the first TCI state is an index of a first beam or reference signal (RS) transmitted in the candidate cell; The method further includes determining the first TCI state or its identifier based on the index of the first beam or RS and a mapping between a TCI state identifier used in the first candidate cell and an index of a beam or RS transmitted in the first candidate cell (1350); A method having the following.

30. The method according to any one of claims 27 to 28, the indication of the first TCI state is a TCI state identifier; The method further includes transmitting to the CU or the DU a mapping between a TCI state identifier used in the first candidate cell and an index of a beam or RS transmitted in the first candidate cell (1310); A method having the following.

31. 31. The method of claim 27, wherein the configuration for the first candidate cell includes an indication of whether the UE should perform a Medium Access Control (MAC) reset when performing the L1 / L2 inter-cell mobility to the first candidate cell.

32. 32. The method of claim 27, wherein communicating with the UE in the first candidate cell based on the first TCI state (1360) comprises: transmitting a control channel of the first candidate cell in a beam or spatial direction corresponding to the first TCI (1361); receiving 1362 uplink data or a scheduling request from the UE in the first candidate cell in a beam or spatial direction corresponding to the first TCI state; A method comprising one or more of:

33. A method according to any one of claims 27 to 32, wherein the DU is associated with the CU and / or is part of the RAN node.

34. 1. A user equipment (UE) (510, 710, 1412, 1500, 1906) configured to communicate with a radio access network (RAN) node (100, 550, 750, 1410, 1600, 1802, 1904) having a central unit (CU) (110, 540, 740) and a distributed unit (DU) (120, 520, 720) providing a serving cell for the UE, wherein the UE: a communication interface circuit (1512) configured to communicate with the CU and at least the DU; a processing circuit (1502) operably coupled to the communication interface circuit, wherein the processing circuit and the communication interface circuit receiving a lower layer signaling message from the candidate DU indicating that the UE should perform L1 / L2-based inter-cell mobility to a first candidate cell provided by the candidate DU, wherein the lower layer signaling message includes: an indicator or identity of the first candidate cell; and an indication of a first transmission configuration indicator (TCI) state to be used by the UE to communicate with the first candidate cell; performing an L1 / L2 mobility procedure toward the first candidate cell and communicating in the first candidate cell based on the first TCI state; The UE is configured as follows:

35. 35. The UE of claim 34, wherein the processing circuitry and the communications interface circuitry are further configured to perform operations corresponding to a method according to any one of claims 2 to 13.

36. 1. A user equipment (UE) (510, 710, 1412, 1500, 1906) configured to communicate with a radio access network (RAN) node (100, 550, 750, 1410, 1600, 1802, 1904) having a central unit (CU) (110, 540, 740) and a distributed unit (DU) (120, 520, 720) providing a serving cell for the UE, the UE further comprising: receiving a lower layer signaling message from the candidate DU indicating that the UE should perform L1 / L2-based inter-cell mobility to a first candidate cell provided by the candidate DU, wherein the lower layer signaling message includes: an indicator or identity of the first candidate cell; and an indication of a first transmission configuration indicator (TCI) state to be used by the UE to communicate with the first candidate cell; performing an L1 / L2 mobility procedure toward the first candidate cell and communicating in the first candidate cell based on the first TCI state; The UE is configured as follows:

37. A UE according to claim 36, further configured to perform operations corresponding to the method according to any of claims 2 to 13.

38. 14. A non-transitory computer-readable medium (1510) having stored thereon computer-executable instructions, when executed by a processing circuit (1502) of a user equipment (UE) (510, 710, 1412, 1500, 1906) configured to communicate with a radio access network (RAN) node (100, 550, 750, 1410, 1600, 1802, 1904) having a central unit (CU) (110, 540, 740) and a distributed unit (DU) (120, 520, 720) that provides a serving cell for the UE, configured to configure the UE to perform operations corresponding to the method of any one of claims 1 to 13.

39. 14. A computer program product (1514) having computer-executable instructions, when executed by a processing circuit (1502) of a user equipment (UE) (510, 710, 1412, 1500, 1906) configured to communicate with a radio access network (RAN) node (100, 550, 750, 1410, 1600, 1802, 1904) having a central unit (CU) (110, 540, 740) and a distributed unit (DU) (120, 520, 720) providing a serving cell for the UE, to configure the UE to perform operations corresponding to the method of any one of claims 1 to 13.

40. A distributed unit (DU) (120, 520, 720) of a radio access network (RAN) node (100, 550, 750, 1410, 1600, 1802, 1904), the DU configured to communicate with a central unit (CU) (110, 540, 740) of the RAN node and configured to provide a serving cell for a user equipment (UE) (510, 710, 1412, 1500, 1906), the DU comprising: a communication interface circuit (1606, 1804) configured to communicate with the CU and the UE; a processing circuit (1602, 1804) operably coupled to the communication interface circuit, whereby the processing circuit and the communication interface circuit Selecting a first candidate cell provided by a candidate DU (130, 530, 730) for L1 / L2-based inter-cell mobility of a UE served by the DU via the serving cell; and transmitting to the UE a lower layer signaling message indicating that the UE should perform L1 / L2-based inter-cell mobility to the first candidate cell, wherein the lower layer signaling message comprises: an indicator or identity of the first candidate cell; and an indication of a first transmission configuration indicator (TCI) state to be used by the UE to communicate with the first candidate cell; and Including, DU.

41. 41. The DU of claim 40, wherein the processing circuitry and the communications interface circuitry are further configured to perform operations corresponding to a method according to any one of claims 15 to 26.

42. A distributed unit (DU) (120, 520, 720) of a radio access network (RAN) node (100, 550, 750, 1410, 1600, 1802, 1904), the DU configured to communicate with a central unit (CU) (110, 540, 740) of the RAN node and to provide a serving cell to a user equipment (UE) (510, 710, 1412, 1500, 1906), the DU further comprising: Selecting a first candidate cell provided by a candidate DU (130, 530, 730) for L1 / L2-based inter-cell mobility of a UE served by the DU via the serving cell; and transmitting to the UE a lower layer signaling message indicating that the UE should perform L1 / L2-based inter-cell mobility to the first candidate cell, wherein the lower layer signaling message comprises: an indicator or identity of the first candidate cell; and an indication of a first transmission configuration indicator (TCI) state to be used by the UE to communicate with the first candidate cell; and Including, DU.

43. The DU of claim 42, further configured to perform operations corresponding to the method of any one of claims 15 to 26.

44. A non-transitory computer-readable medium (1604, 1804) having stored thereon computer-executable instructions that, when executed by a processing circuit (1402, 1604) of a distributed unit (DU) (120, 520, 720) of a radio access network (RAN) node (100, 550, 750, 1410, 1600, 1802, 1904), configure the DU to perform operations corresponding to the method of any one of claims 14 to 26.

45. A computer program product (1604a, 1804a) having computer-executable instructions which, when executed by a processing circuit (1402, 1604) of a distributed unit (DU) (120, 520, 720) of a radio access network (RAN) node (100, 550, 750, 1410, 1600, 1802, 1904), configures the DU to perform operations corresponding to the method of any one of claims 14 to 26.

46. A candidate distribution unit (DU) (130, 530, 730) of a radio access network (RAN) node (100, 550, 750, 1410, 1600, 1802, 1904), the candidate DU configured to communicate with a central unit (CU) (110, 540, 740) of the RAN node, the candidate DU comprising: a communication interface circuit (1606, 1804) configured to communicate with a user equipment (UE) (510, 710, 1412, 1500, 1906) and the CU via one or more cells provided by the candidate DU; a processing circuit (1602, 1804) operably coupled to the communication interface circuit, whereby the processing circuit and the communication interface circuit receiving a request from the CU or from a DU (120, 520, 720) serving the UE via a serving cell to configure the UE with at least one candidate cell for L1 / L2-based inter-cell mobility; Sending configurations for one or more candidate cells provided by the candidate DU, including a first candidate cell, to the CU or the DU; Receive a message from the DU indicating an L1 / L2 mobility procedure by the UE, wherein the message comprises: an indicator or identity of the first candidate cell for L1 / L2 based inter-cell mobility of the UE; and an indication of a first transmission configuration indicator (TCI) state to be used by the UE to communicate with the first candidate cell; A candidate DU configured to communicate with the UE in the first candidate cell based on the first TCI state.

47. A candidate DU according to claim 46, wherein the processing circuitry and communication interface circuitry are further configured to perform operations corresponding to a method according to any one of claims 28 to 33.

48. A candidate distribution unit (DU) (130, 530, 730) of a radio access network (RAN) node (100, 550, 750, 1410, 1600, 1802, 1904), the candidate DU configured to communicate with a central unit (CU) (110, 540, 740) of the RAN node, the candidate DU further comprising: receiving a request from the CU or from a DU (120, 520, 720) serving a user equipment (UE) (510, 710, 1412, 1500, 1906) via a serving cell to configure the UE with at least one candidate cell for L1 / L2-based inter-cell mobility; Sending configurations for one or more candidate cells provided by the candidate DU, including a first candidate cell, to the CU or the DU; Receive a message from the DU indicating an L1 / L2 mobility procedure by the UE, wherein the message comprises: an indicator or identity of the first candidate cell for L1 / L2 based inter-cell mobility of the UE; and an indication of a first transmission configuration indicator (TCI) state to be used by the UE to communicate with the first candidate cell; A candidate DU configured to communicate with the UE in the first candidate cell based on the first TCI state.

49. A candidate DU according to claim 48, further configured to perform operations corresponding to the method according to any one of claims 28 to 33.

50. A non-transitory computer-readable medium (1604, 1804) having stored thereon computer-executable instructions that, when executed by a processing circuit (1602, 1804) of a candidate distribution unit (DU) (130, 530, 730) of a radio access network (RAN) node (100, 550, 750, 1410, 1600, 1802, 1904), configures the candidate DU to perform operations corresponding to the method of any one of claims 27 to 33.

51. A computer program product (1604a, 1804a) having computer-executable instructions that, when executed by a processing circuit (1602, 1804) of a candidate distribution unit (DU) (130, 530, 730) of a radio access network (RAN) node (100, 550, 750, 1410, 1600, 1802, 1904), configures the candidate DU to perform operations corresponding to the method of any one of claims 27 to 33.

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