WO2024092699A1

WO2024092699A1 - Timing advance indications for candidate serving cells

Info

Publication number: WO2024092699A1
Application number: PCT/CN2022/129799
Authority: WO
Inventors: Fang Yuan; Yan Zhou; Tao Luo
Original assignee: Qualcomm Incorporated
Priority date: 2022-11-04
Filing date: 2022-11-04
Publication date: 2024-05-10

Abstract

Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment (UE) may receive a timing advance (TA) indication associated with a candidate serving cell configured for layer 1/layer 2 (L1/L2) mobility. The UE may receive, after or with the TA indication, an L1 message or an L2 message instructing the UE to switch to the candidate serving cell. Accordingly, the UE may communicate with the candidate serving cell based on the L1 message or the L2 message. Numerous other aspects are described.

Description

TIMING ADVANCE INDICATIONS FOR CANDIDATE SERVING CELLS

FIELD OF THE DISCLOSURE

Aspects of the present disclosure generally relate to wireless communication and to techniques and apparatuses for timing advance indications for candidate serving cells.

BACKGROUND

Wireless communication systems are widely deployed to provide various telecommunication services such as telephony, video, data, messaging, and broadcasts. Typical wireless communication systems may employ multiple-access technologies capable of supporting communication with multiple users by sharing available system resources (e.g., bandwidth, transmit power, or the like) . Examples of such multiple-access technologies include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, orthogonal frequency division multiple access (OFDMA) systems, single-carrier frequency division multiple access (SC-FDMA) systems, time division synchronous code division multiple access (TD-SCDMA) systems, and Long Term Evolution (LTE) . LTE/LTE-Advanced is a set of enhancements to the Universal Mobile Telecommunications System (UMTS) mobile standard promulgated by the Third Generation Partnership Project (3GPP) .

A wireless network may include one or more network nodes that support communication for wireless communication devices, such as a user equipment (UE) or multiple UEs. A UE may communicate with a network node via downlink communications and uplink communications. “Downlink” (or “DL” ) refers to a communication link from the network node to the UE, and “uplink” (or “UL” ) refers to a communication link from the UE to the network node. Some wireless networks may support device-to-device communication, such as via a local link (e.g., a sidelink (SL) , a wireless local area network (WLAN) link, and/or a wireless personal area network (WPAN) link, among other examples) .

The above multiple access technologies have been adopted in various telecommunication standards to provide a common protocol that enables different UEs to communicate on a municipal, national, regional, and/or global level. New Radio (NR) , which may be referred to as 5G, is a set of enhancements to the LTE mobile standard promulgated by the 3GPP. NR is designed to better support mobile broadband internet access by improving spectral efficiency, lowering costs, improving services, making use of new spectrum, and better integrating with other open standards using orthogonal frequency division multiplexing (OFDM) with a cyclic prefix (CP) (CP-OFDM) on the downlink, using CP-OFDM and/or single-carrier frequency division multiplexing (SC-FDM) (also known as discrete Fourier transform spread OFDM (DFT-s-OFDM) ) on the uplink, as well as supporting beamforming, multiple-input multiple-output (MIMO) antenna technology, and carrier aggregation. As the demand for mobile broadband access continues to increase, further improvements in LTE, NR, and other radio access technologies remain useful.

SUMMARY

Some aspects described herein relate to an apparatus for wireless communication at a user equipment (UE) . The apparatus may include a memory and one or more processors coupled to the memory. The one or more processors may be configured to receive a timing advance (TA) indication associated with a candidate serving cell configured for layer 1/layer 2 (L1/L2) mobility. The one or more processors may be configured to receive, after or with the TA indication, an L1 message or an L2 message instructing the UE to switch to the candidate serving cell. The one or more processors may be configured to communicate with the candidate serving cell based on the L1 message or the L2 message.

Some aspects described herein relate to an apparatus for wireless communication at a network node. The apparatus may include a memory and one or more processors coupled to the memory. The one or more processors may be configured to transmit a TA indication associated with a candidate serving cell configured for L1/L2 mobility. The one or more processors may be configured to transmit, after or with the TA indication, an L1 message or an L2 message instructing a UE to switch to the candidate serving cell.

Some aspects described herein relate to an apparatus for wireless communication at a UE. The apparatus may include a memory and one or more processors coupled to the memory. The one or more processors may be configured to receive an L1 message or an L2 message instructing the UE to switch to a candidate serving cell. The one or more processors may be configured to receive, after the L1 message or the L2 message, a TA indication associated with the candidate serving cell. The one or more processors may be configured to communicate with the candidate serving cell based on the TA indication.

Some aspects described herein relate to an apparatus for wireless communication at a network node. The apparatus may include a memory and one or more processors coupled to the memory. The one or more processors may be configured to transmit a TA indication associated with a candidate serving cell configured for L1/L2 mobility after an L1 message or an L2 message instructing a UE to switch to the candidate serving cell. The one or more processors may be configured to communicate with the UE based on the TA indication.

Some aspects described herein relate to a method of wireless communication performed by a UE. The method may include receiving a TA indication associated with a candidate serving cell configured for L1/L2 mobility. The method may include receiving, after or with the TA indication, an L1 message or an L2 message instructing the UE to switch to the candidate serving cell. The method may include communicating with the candidate serving cell based on the L1 message or the L2 message.

Some aspects described herein relate to a method of wireless communication performed by a network node. The method may include transmitting a TA indication associated with a candidate serving cell configured for L1/L2 mobility. The method may include transmitting, after or with the TA indication, an L1 message or an L2 message instructing a UE to switch to the candidate serving cell.

Some aspects described herein relate to a method of wireless communication performed by a UE. The method may include receiving an L1 message or an L2 message instructing the UE to switch to a candidate serving cell. The method may include receiving, after the L1 message or the L2 message, a TA indication associated with the candidate serving cell. The method may include communicating with the candidate serving cell based on the TA indication.

Some aspects described herein relate to a method of wireless communication performed by a network node. The method may include transmitting a TA indication associated with a candidate serving cell configured for L1/L2 mobility after an L1 message or an L2 message instructing a UE to switch to the candidate serving cell. The method may include communicating with the UE based on the TA indication.

Some aspects described herein relate to a non-transitory computer-readable medium that stores a set of instructions for wireless communication by a UE. The set of instructions, when executed by one or more processors of the UE, may cause the UE to receive a TA indication associated with a candidate serving cell configured for L1/L2 mobility. The set of instructions, when executed by one or more processors of the UE, may cause the UE to receive, after or with the TA indication, an L1 message or an L2 message instructing the UE to switch to the candidate serving cell. The set of instructions, when executed by one or more processors of the UE, may cause the UE to communicate with the candidate serving cell based on the L1 message or the L2 message.

Some aspects described herein relate to a non-transitory computer-readable medium that stores a set of instructions for wireless communication by a network node. The set of instructions, when executed by one or more processors of the network node, may cause the network node to transmit a TA indication associated with a candidate serving cell configured for L1/L2 mobility. The set of instructions, when executed by one or more processors of the network node, may cause the network node to transmit, after or with the TA indication, an L1 message or an L2 message instructing a UE to switch to the candidate serving cell.

Some aspects described herein relate to a non-transitory computer-readable medium that stores a set of instructions for wireless communication by a UE. The set of instructions, when executed by one or more processors of the UE, may cause the UE to receive an L1 message or a L2 message instructing the UE to switch to a candidate serving cell. The set of instructions, when executed by one or more processors of the UE, may cause the UE to receive, after the L1 message or the L2 message, a TA indication associated with the candidate serving cell. The set of instructions, when executed by one or more processors of the UE, may cause the UE to communicate with the candidate serving cell based on the TA indication.

Some aspects described herein relate to a non-transitory computer-readable medium that stores a set of instructions for wireless communication by a network node. The set of instructions, when executed by one or more processors of the network node, may cause the network node to transmit a TA indication associated with a candidate serving cell configured for L1/L2 mobility after an L1 message or an L2 message instructing a UE to switch to the candidate serving cell. The set of instructions, when executed by one or more processors of the network node, may cause the network node to communicate with the UE based on the TA indication.

Some aspects described herein relate to an apparatus for wireless communication. The apparatus may include means for receiving a TA indication associated with a candidate serving cell configured for L1/L2 mobility. The apparatus may include means for receiving, after or with the TA indication, an L1 message or an L2 message instructing the apparatus to switch to the candidate serving cell. The apparatus may include means for communicating with the candidate serving cell based on the L1 message or the L2 message.

Some aspects described herein relate to an apparatus for wireless communication. The apparatus may include means for transmitting a TA indication associated with a candidate serving cell configured for L1/L2 mobility. The apparatus may include means for transmitting, after or with the TA indication, an L1 message or an L2 message instructing a UE to switch to the candidate serving cell.

Some aspects described herein relate to an apparatus for wireless communication. The apparatus may include means for receiving an L1 message or an L2 message instructing the apparatus to switch to a candidate serving cell. The apparatus may include means for receiving, after the L1 message or the L2 message, a TA indication associated with the candidate serving cell. The apparatus may include means for communicating with the candidate serving cell based on the TA indication.

Some aspects described herein relate to an apparatus for wireless communication. The apparatus may include means for transmitting a TA indication associated with a candidate serving cell configured for L1/L2 mobility after an L1 message or an L2 message instructing a UE to switch to the candidate serving cell. The apparatus may include means for communicating with the UE based on the TA indication.

Aspects generally include a method, apparatus, system, computer program product, non-transitory computer-readable medium, user equipment, base station, network entity, network node, wireless communication device, and/or processing system as substantially described herein with reference to and as illustrated by the drawings and specification.

The foregoing has outlined rather broadly the features and technical advantages of examples according to the disclosure in order that the detailed description that follows may be better understood. Additional features and advantages will be described hereinafter. The conception and specific examples disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present disclosure. Such equivalent constructions do not depart from the scope of the appended claims. Characteristics of the concepts disclosed herein, both their organization and method of operation, together with associated advantages, will be better understood from the following description when considered in connection with the accompanying figures. Each of the figures is provided for the purposes of illustration and description, and not as a definition of the limits of the claims.

While aspects are described in the present disclosure by illustration to some examples, those skilled in the art will understand that such aspects may be implemented in many different arrangements and scenarios. Techniques described herein may be implemented using different platform types, devices, systems, shapes, sizes, and/or packaging arrangements. For example, some aspects may be implemented via integrated chip embodiments or other non-module-component based devices (e.g., end-user devices, vehicles, communication devices, computing devices, industrial equipment, retail/purchasing devices, medical devices, and/or artificial intelligence devices) . Aspects may be implemented in chip-level components, modular components, non-modular components, non-chip-level components, device-level components, and/or system-level components. Devices incorporating described aspects and features may include additional components and features for implementation and practice of claimed and described aspects. For example, transmission and reception of wireless signals may include one or more components for analog and digital purposes (e.g., hardware components including antennas, radio frequency (RF) chains, power amplifiers, modulators, buffers, processors, interleavers, adders, and/or summers) . It is intended that aspects described herein may be practiced in a wide variety of devices, components, systems, distributed arrangements, and/or end-user devices of varying size, shape, and constitution.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the above-recited features of the present disclosure can be understood in detail, a more particular description, briefly summarized above, may be had by reference to aspects, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only certain typical aspects of this disclosure and are therefore not to be considered limiting of its scope, for the description may admit to other equally effective aspects. The same reference numbers in different drawings may identify the same or similar elements.

Fig. 1 is a diagram illustrating an example of a wireless network, in accordance with the present disclosure.

Fig. 2 is a diagram illustrating an example of a network node in communication with a user equipment in a wireless network, in accordance with the present disclosure.

Fig. 3 is a diagram illustrating an example disaggregated base station architecture, in accordance with the present disclosure.

Fig. 4 is a diagram illustrating an example of timing advances (TAs) for active and candidate serving cells, in accordance with the present disclosure.

Fig. 5 is a diagram illustrating an example associated with providing TA indications before or with an instruction to switch to a candidate serving cell, in accordance with the present disclosure.

Fig. 6 is a diagram illustrating an example associated with providing TA indications after an instruction to switch to a candidate serving cell, in accordance with the present disclosure.

Figs. 7, 8, 9, and 10 are diagrams illustrating example processes associated with TA indications associated with a candidate serving cell, in accordance with the present disclosure.

Figs. 11 and 12 are diagrams of example apparatuses for wireless communication, in accordance with the present disclosure.

DETAILED DESCRIPTION

Various aspects of the disclosure are described more fully hereinafter with reference to the accompanying drawings. This disclosure may, however, be embodied in many different forms and should not be construed as limited to any specific structure or function presented throughout this disclosure. Rather, these aspects are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. One skilled in the art should appreciate that the scope of the disclosure is intended to cover any aspect of the disclosure disclosed herein, whether implemented independently of or combined with any other aspect of the disclosure. For example, an apparatus may be implemented or a method may be practiced using any number of the aspects set forth herein. In addition, the scope of the disclosure is intended to cover such an apparatus or method which is practiced using other structure, functionality, or structure and functionality in addition to or other than the various aspects of the disclosure set forth herein. It should be understood that any aspect of the disclosure disclosed herein may be embodied by one or more elements of a claim.

Several aspects of telecommunication systems will now be presented with reference to various apparatuses and techniques. These apparatuses and techniques will be described in the following detailed description and illustrated in the accompanying drawings by various blocks, modules, components, circuits, steps, processes, algorithms, or the like (collectively referred to as “elements” ) . These elements may be implemented using hardware, software, or combinations thereof. Whether such elements are implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system.

While aspects may be described herein using terminology commonly associated with a 5G or New Radio (NR) radio access technology (RAT) , aspects of the present disclosure can be applied to other RATs, such as a 3G RAT, a 4G RAT, and/or a RAT subsequent to 5G (e.g., 6G) .

Various aspects relate generally to wireless communication and more particularly to timing advance (TA) commands. Some aspects more specifically relate to providing a TA command, associated with a candidate serving cell, before or with a command to move from an active serving cell to the candidate serving cell. For example, the candidate serving cell may be associated with a layer 1/layer 2 (L1/L2) mobility configuration such that the command is included in an L1 message or an L2 message. A user equipment (UE) may thus perform a timing adjustment before communicating with the candidate serving cell. Alternatively, some aspects more specifically relate to providing a TA command, associated with a candidate serving cell, after a command to move from an active serving cell to the candidate serving cell. As a result, a UE may perform a timing adjustment after switching to the candidate serving cell.

Particular aspects of the subject matter described in this disclosure can be implemented to realize one or more of the following potential advantages. Performing a timing adjustment increases quality and reliability of uplink transmissions from a UE to a network. More specifically, providing a TA command before or with a command to switch from an active serving cell to a candidate serving cell enables the UE to perform a timing adjustment before communicating with a candidate serving cell. As a result, the UE experiences reduced latency because the UE can begin communicating with the candidate serving cell immediately after switching. Additionally, the UE experiences increased reliability and quality of communications, which conserves power and processing resources that would otherwise have been expended on retransmissions. Alternatively, providing a TA command after a command to switch from an active serving cell to a candidate serving cell enables the UE to perform a timing adjustment after switching to a candidate serving cell. Because the candidate serving cell provides the TA command, the active serving cell conserves power and processing resources that would otherwise have been expended on backhaul communications to determine a TA value associated with the candidate serving cell. Additionally, the UE experiences increased reliability and quality of communications, which conserves power and processing resources that would otherwise have been expended on retransmissions.

Fig. 1 is a diagram illustrating an example of a wireless network 100, in accordance with the present disclosure. The wireless network 100 may be or may include elements of a 5G (e.g., NR) network and/or a 4G (e.g., Long Term Evolution (LTE) ) network, among other examples. The wireless network 100 may include one or more network nodes 110 (shown as a network node 110a, a network node 110b, a network node 110c, and a network node 110d) , a UE 120 or multiple UEs 120 (shown as a UE 120a, a UE 120b, a UE 120c, a UE 120d, and a UE 120e) , and/or other entities. A network node 110 is a network node that communicates with UEs 120. As shown, a network node 110 may include one or more network nodes. For example, a network node 110 may be an aggregated network node, meaning that the aggregated network node is configured to utilize a radio protocol stack that is physically or logically integrated within a single radio access network (RAN) node (e.g., within a single device or unit) . As another example, a network node 110 may be a disaggregated network node (sometimes referred to as a disaggregated base station) , meaning that the network node 110 is configured to utilize a protocol stack that is physically or logically distributed among two or more nodes (such as one or more central units (CUs) , one or more distributed units (DUs) , or one or more radio units (RUs) ) .

In some examples, a network node 110 is or includes a network node that communicates with UEs 120 via a radio access link, such as an RU. In some examples, a network node 110 is or includes a network node that communicates with other network nodes 110 via a fronthaul link or a midhaul link, such as a DU. In some examples, a network node 110 is or includes a network node that communicates with other network nodes 110 via a midhaul link or a core network via a backhaul link, such as a CU. In some examples, a network node 110 (such as an aggregated network node 110 or a disaggregated network node 110) may include multiple network nodes, such as one or more RUs, one or more CUs, and/or one or more DUs. A network node 110 may include, for example, an NR base station, an LTE base station, a Node B, an eNB (e.g., in 4G) , a gNB (e.g., in 5G) , an access point, a transmission reception point (TRP) , a DU, an RU, a CU, a mobility element of a network, a core network node, a network element, a network equipment, a RAN node, or a combination thereof. In some examples, the network nodes 110 may be interconnected to one another or to one or more other network nodes 110 in the wireless network 100 through various types of fronthaul, midhaul, and/or backhaul interfaces, such as a direct physical connection, an air interface, or a virtual network, using any suitable transport network.

In some examples, a network node 110 may provide communication coverage for a particular geographic area. In the Third Generation Partnership Project (3GPP) , the term “cell” can refer to a coverage area of a network node 110 and/or a network node subsystem serving this coverage area, depending on the context in which the term is used. A network node 110 may provide communication coverage for a macro cell, a pico cell, a femto cell, and/or another type of cell. A macro cell may cover a relatively large geographic area (e.g., several kilometers in radius) and may allow unrestricted access by UEs 120 with service subscriptions. A pico cell may cover a relatively small geographic area and may allow unrestricted access by UEs 120 with service subscriptions. A femto cell may cover a relatively small geographic area (e.g., a home) and may allow restricted access by UEs 120 having association with the femto cell (e.g., UEs 120 in a closed subscriber group (CSG) ) . A network node 110 for a macro cell may be referred to as a macro network node. A network node 110 for a pico cell may be referred to as a pico network node. A network node 110 for a femto cell may be referred to as a femto network node or an in-home network node. In the example shown in Fig. 1, the network node 110a may be a macro network node for a macro cell 102a, the network node 110b may be a pico network node for a pico cell 102b, and the network node 110c may be a femto network node for a femto cell 102c. A network node may support one or multiple (e.g., three) cells. In some examples, a cell may not necessarily be stationary, and the geographic area of the cell may move according to the location of a network node 110 that is mobile (e.g., a mobile network node) .

In some aspects, the terms “base station” or “network node” may refer to an aggregated base station, a disaggregated base station, an integrated access and backhaul (IAB) node, a relay node, or one or more components thereof. For example, in some aspects, “base station” or “network node” may refer to a CU, a DU, an RU, a Near-Real Time (Near-RT) RAN Intelligent Controller (RIC) , or a Non-Real Time (Non-RT) RIC, or a combination thereof. In some aspects, the terms “base station” or “network node” may refer to one device configured to perform one or more functions, such as those described herein in connection with the network node 110. In some aspects, the terms “base station” or “network node” may refer to a plurality of devices configured to perform the one or more functions. For example, in some distributed systems, each of a quantity of different devices (which may be located in the same geographic location or in different geographic locations) may be configured to perform at least a portion of a function, or to duplicate performance of at least a portion of the function, and the terms “base station” or “network node” may refer to any one or more of those different devices. In some aspects, the terms “base station” or “network node” may refer to one or more virtual base stations or one or more virtual base station functions. For example, in some aspects, two or more base station functions may be instantiated on a single device. In some aspects, the terms “base station” or “network node” may refer to one of the base station functions and not another. In this way, a single device may include more than one base station.

The wireless network 100 may include one or more relay stations. A relay station is a network node that can receive a transmission of data from an upstream node (e.g., a network node 110 or a UE 120) and send a transmission of the data to a downstream node (e.g., a UE 120 or a network node 110) . A relay station may be a UE 120 that can relay transmissions for other UEs 120. In the example shown in Fig. 1, the network node 110d (e.g., a relay network node) may communicate with the network node 110a (e.g., a macro network node) and the UE 120d in order to facilitate communication between the network node 110a and the UE 120d. A network node 110 that relays communications may be referred to as a relay station, a relay base station, a relay network node, a relay node, a relay, or the like.

The wireless network 100 may be a heterogeneous network that includes network nodes 110 of different types, such as macro network nodes, pico network nodes, femto network nodes, relay network nodes, or the like. These different types of network nodes 110 may have different transmit power levels, different coverage areas, and/or different impacts on interference in the wireless network 100. For example, macro network nodes may have a high transmit power level (e.g., 5 to 40 watts) whereas pico network nodes, femto network nodes, and relay network nodes may have lower transmit power levels (e.g., 0.1 to 2 watts) .

A network controller 130 may couple to or communicate with a set of network nodes 110 and may provide coordination and control for these network nodes 110. The network controller 130 may communicate with the network nodes 110 via a backhaul communication link or a midhaul communication link. The network nodes 110 may communicate with one another directly or indirectly via a wireless or wireline backhaul communication link. In some aspects, the network controller 130 may be a CU or a core network device, or may include a CU or a core network device.

The UEs 120 may be dispersed throughout the wireless network 100, and each UE 120 may be stationary or mobile. A UE 120 may include, for example, an access terminal, a terminal, a mobile station, and/or a subscriber unit. A UE 120 may be a cellular phone (e.g., a smart phone) , a personal digital assistant (PDA) , a wireless modem, a wireless communication device, a handheld device, a laptop computer, a cordless phone, a wireless local loop (WLL) station, a tablet, a camera, a gaming device, a netbook, a smartbook, an ultrabook, a medical device, a biometric device, a wearable device (e.g., a smart watch, smart clothing, smart glasses, a smart wristband, smart jewelry (e.g., a smart ring or a smart bracelet) ) , an entertainment device (e.g., a music device, a video device, and/or a satellite radio) , a vehicular component or sensor, a smart meter/sensor, industrial manufacturing equipment, a global positioning system device, a UE function of a network node, and/or any other suitable device that is configured to communicate via a wireless or wired medium.

Some UEs 120 may be considered machine-type communication (MTC) or evolved or enhanced machine-type communication (eMTC) UEs. An MTC UE and/or an eMTC UE may include, for example, a robot, a drone, a remote device, a sensor, a meter, a monitor, and/or a location tag, that may communicate with a network node, another device (e.g., a remote device) , or some other entity. Some UEs 120 may be considered Internet-of-Things (IoT) devices, and/or may be implemented as NB-IoT (narrowband IoT) devices. Some UEs 120 may be considered a Customer Premises Equipment. A UE 120 may be included inside a housing that houses components of the UE 120, such as processor components and/or memory components. In some examples, the processor components and the memory components may be coupled together. For example, the processor components (e.g., one or more processors) and the memory components (e.g., a memory) may be operatively coupled, communicatively coupled, electronically coupled, and/or electrically coupled.

In general, any number of wireless networks 100 may be deployed in a given geographic area. Each wireless network 100 may support a particular RAT and may operate on one or more frequencies. A RAT may be referred to as a radio technology, an air interface, or the like. A frequency may be referred to as a carrier, a frequency channel, or the like. Each frequency may support a single RAT in a given geographic area in order to avoid interference between wireless networks of different RATs. In some cases, NR or 5G RAT networks may be deployed.

In some examples, two or more UEs 120 (e.g., shown as UE 120a and UE 120e) may communicate directly using one or more sidelink channels (e.g., without using a network node 110 as an intermediary to communicate with one another) . For example, the UEs 120 may communicate using peer-to-peer (P2P) communications, device-to-device (D2D) communications, a vehicle-to-everything (V2X) protocol (e.g., which may include a vehicle-to-vehicle (V2V) protocol, a vehicle-to-infrastructure (V2I) protocol, or a vehicle-to-pedestrian (V2P) protocol) , and/or a mesh network. In such examples, a UE 120 may perform scheduling operations, resource selection operations, and/or other operations described elsewhere herein as being performed by the network node 110.

Devices of the wireless network 100 may communicate using the electromagnetic spectrum, which may be subdivided by frequency or wavelength into various classes, bands, channels, or the like. For example, devices of the wireless network 100 may communicate using one or more operating bands. In 5G NR, two initial operating bands have been identified as frequency range designations FR1 (410 MHz –7.125 GHz) and FR2 (24.25 GHz –52.6 GHz) . It should be understood that although a portion of FR1 is greater than 6 GHz, FR1 is often referred to (interchangeably) as a “Sub-6 GHz” band in various documents and articles. A similar nomenclature issue sometimes occurs with regard to FR2, which is often referred to (interchangeably) as a “millimeter wave” band in documents and articles, despite being different from the extremely high frequency (EHF) band (30 GHz –300 GHz) which is identified by the International Telecommunications Union (ITU) as a “millimeter wave” band.

The frequencies between FR1 and FR2 are often referred to as mid-band frequencies. Recent 5G NR studies have identified an operating band for these mid-band frequencies as frequency range designation FR3 (7.125 GHz –24.25 GHz) . Frequency bands falling within FR3 may inherit FR1 characteristics and/or FR2 characteristics, and thus may effectively extend features of FR1 and/or FR2 into mid-band frequencies. In addition, higher frequency bands are currently being explored to extend 5G NR operation beyond 52.6 GHz. For example, three higher operating bands have been identified as frequency range designations FR4a or FR4-1 (52.6 GHz –71 GHz) , FR4 (52.6 GHz –114.25 GHz) , and FR5 (114.25 GHz –300 GHz) . Each of these higher frequency bands falls within the EHF band.

With the above examples in mind, unless specifically stated otherwise, it should be understood that the term “sub-6 GHz” or the like, if used herein, may broadly represent frequencies that may be less than 6 GHz, may be within FR1, or may include mid-band frequencies. Further, unless specifically stated otherwise, it should be understood that the term “millimeter wave” or the like, if used herein, may broadly represent frequencies that may include mid-band frequencies, may be within FR2, FR4, FR4-a or FR4-1, and/or FR5, or may be within the EHF band. It is contemplated that the frequencies included in these operating bands (e.g., FR1, FR2, FR3, FR4, FR4-a, FR4-1, and/or FR5) may be modified, and techniques described herein are applicable to those modified frequency ranges.

In some aspects, the UE 120 may include a communication manager 140. As described in more detail elsewhere herein, the communication manager 140 may receive a TA indication associated with a candidate serving cell configured for L1/L2 mobility; receive, after or with the TA indication, an L1 message or an L2 message instructing the UE 120 to switch to the candidate serving cell; and communicate with the candidate serving cell based on the L1 message or the L2 message. Alternatively, as described in more detail elsewhere herein, the communication manager 140 may receive an L1 message or an L2 message instructing the UE 120 to switch to a candidate serving cell; receive, after the L1 message or the L2 message, a TA indication associated with the candidate serving cell; and communicate with the candidate serving cell based on the TA indication. Additionally, or alternatively, the communication manager 140 may perform one or more other operations described herein.

In some aspects, the network node 110 may include a communication manager 150. As described in more detail elsewhere herein, the communication manager 150 may transmit a TA indication associated with a candidate serving cell configured for L1/L2 mobility and transmit, after or with the TA indication, an L1 message or an L2 message instructing a UE (e.g., the UE 120) to switch to the candidate serving cell. Alternatively, as described in more detail elsewhere herein, the communication manager 150 may transmit a TA indication associated with a candidate serving cell configured for L1/L2 mobility after an L1 message or an L2 message instructing a UE (e.g., the UE 120) to switch to the candidate serving cell and communicate with the UE 120 based on the TA indication. Additionally, or alternatively, the communication manager 150 may perform one or more other operations described herein.

As indicated above, Fig. 1 is provided as an example. Other examples may differ from what is described with regard to Fig. 1.

Fig. 2 is a diagram illustrating an example 200 of a network node 110 in communication with a UE 120 in a wireless network 100, in accordance with the present disclosure. The network node 110 may be equipped with a set of antennas 234a through 234t, such as T antennas (T ≥ 1) . The UE 120 may be equipped with a set of antennas 252a through 252r, such as R antennas (R ≥ 1) . The network node 110 of example 200 includes one or more radio frequency components, such as antennas 234 and a modem 232. In some examples, a network node 110 may include an interface, a communication component, or another component that facilitates communication with the UE 120 or another network node. Some network nodes 110 may not include radio frequency components that facilitate direct communication with the UE 120, such as one or more CUs, or one or more DUs.

At the network node 110, a transmit processor 220 may receive data, from a data source 212, intended for the UE 120 (or a set of UEs 120) . The transmit processor 220 may select one or more modulation and coding schemes (MCSs) for the UE 120 based at least in part on one or more channel quality indicators (CQIs) received from that UE 120. The network node 110 may process (e.g., encode and modulate) the data for the UE 120 based at least in part on the MCS (s) selected for the UE 120 and may provide data symbols for the UE 120. The transmit processor 220 may process system information (e.g., for semi-static resource partitioning information (SRPI) ) and control information (e.g., CQI requests, grants, and/or upper layer signaling) and provide overhead symbols and control symbols. The transmit processor 220 may generate reference symbols for reference signals (e.g., a cell-specific reference signal (CRS) or a demodulation reference signal (DMRS) ) and synchronization signals (e.g., a primary synchronization signal (PSS) or a secondary synchronization signal (SSS) ) . A transmit (TX) multiple-input multiple-output (MIMO) processor 230 may perform spatial processing (e.g., precoding) on the data symbols, the control symbols, the overhead symbols, and/or the reference symbols, if applicable, and may provide a set of output symbol streams (e.g., T output symbol streams) to a corresponding set of modems 232 (e.g., T modems) , shown as modems 232a through 232t. For example, each output symbol stream may be provided to a modulator component (shown as MOD) of a modem 232. Each modem 232 may use a respective modulator component to process a respective output symbol stream (e.g., for OFDM) to obtain an output sample stream. Each modem 232 may further use a respective modulator component to process (e.g., convert to analog, amplify, filter, and/or upconvert) the output sample stream to obtain a downlink signal. The modems 232a through 232t may transmit a set of downlink signals (e.g., T downlink signals) via a corresponding set of antennas 234 (e.g., T antennas) , shown as antennas 234a through 234t.

At the UE 120, a set of antennas 252 (shown as antennas 252a through 252r) may receive the downlink signals from the network node 110 and/or other network nodes 110 and may provide a set of received signals (e.g., R received signals) to a set of modems 254 (e.g., R modems) , shown as modems 254a through 254r. For example, each received signal may be provided to a demodulator component (shown as DEMOD) of a modem 254. Each modem 254 may use a respective demodulator component to condition (e.g., filter, amplify, downconvert, and/or digitize) a received signal to obtain input samples. Each modem 254 may use a demodulator component to further process the input samples (e.g., for OFDM) to obtain received symbols. A MIMO detector 256 may obtain received symbols from the modems 254, may perform MIMO detection on the received symbols if applicable, and may provide detected symbols. A receive processor 258 may process (e.g., demodulate and decode) the detected symbols, may provide decoded data for the UE 120 to a data sink 260, and may provide decoded control information and system information to a controller/processor 280. The term “controller/processor” may refer to one or more controllers, one or more processors, or a combination thereof. A channel processor may determine a reference signal received power (RSRP) parameter, a received signal strength indicator (RSSI) parameter, a reference signal received quality (RSRQ) parameter, and/or a CQI parameter, among other examples. In some examples, one or more components of the UE 120 may be included in a housing 284.

The network controller 130 may include a communication unit 294, a controller/processor 290, and a memory 292. The network controller 130 may include, for example, one or more devices in a core network. The network controller 130 may communicate with the network node 110 via the communication unit 294.

One or more antennas (e.g., antennas 234a through 234t and/or antennas 252a through 252r) may include, or may be included within, one or more antenna panels, one or more antenna groups, one or more sets of antenna elements, and/or one or more antenna arrays, among other examples. An antenna panel, an antenna group, a set of antenna elements, and/or an antenna array may include one or more antenna elements (within a single housing or multiple housings) , a set of coplanar antenna elements, a set of non-coplanar antenna elements, and/or one or more antenna elements coupled to one or more transmission and/or reception components, such as one or more components of Fig. 2.

On the uplink, at the UE 120, a transmit processor 264 may receive and process data from a data source 262 and control information (e.g., for reports that include RSRP, RSSI, RSRQ, and/or CQI) from the controller/processor 280. The transmit processor 264 may generate reference symbols for one or more reference signals. The symbols from the transmit processor 264 may be precoded by a TX MIMO processor 266 if applicable, further processed by the modems 254 (e.g., for DFT-s-OFDM or CP-OFDM) , and transmitted to the network node 110. In some examples, the modem 254 of the UE 120 may include a modulator and a demodulator. In some examples, the UE 120 includes a transceiver. The transceiver may include any combination of the antenna (s) 252, the modem (s) 254, the MIMO detector 256, the receive processor 258, the transmit processor 264, and/or the TX MIMO processor 266. The transceiver may be used by a processor (e.g., the controller/processor 280) and the memory 282 to perform aspects of any of the methods described herein (e.g., with reference to Figs. 5-12) .

At the network node 110, the uplink signals from UE 120 and/or other UEs may be received by the antennas 234, processed by the modem 232 (e.g., a demodulator component, shown as DEMOD, of the modem 232) , detected by a MIMO detector 236 if applicable, and further processed by a receive processor 238 to obtain decoded data and control information sent by the UE 120. The receive processor 238 may provide the decoded data to a data sink 239 and provide the decoded control information to the controller/processor 240. The network node 110 may include a communication unit 244 and may communicate with the network controller 130 via the communication unit 244. The network node 110 may include a scheduler 246 to schedule one or more UEs 120 for downlink and/or uplink communications. In some examples, the modem 232 of the network node 110 may include a modulator and a demodulator. In some examples, the network node 110 includes a transceiver. The transceiver may include any combination of the antenna (s) 234, the modem (s) 232, the MIMO detector 236, the receive processor 238, the transmit processor 220, and/or the TX MIMO processor 230. The transceiver may be used by a processor (e.g., the controller/processor 240) and the memory 242 to perform aspects of any of the methods described herein (e.g., with reference to Figs. 5-12) .

The controller/processor 240 of the network node 110, the controller/processor 280 of the UE 120, and/or any other component (s) of Fig. 2 may perform one or more techniques associated with TA indications for candidate serving cells, as described in more detail elsewhere herein. For example, the controller/processor 240 of the network node 110, the controller/processor 280 of the UE 120, and/or any other component (s) of Fig. 2 may perform or direct operations of, for example, process 700 of Fig. 7, process 800 of Fig. 8, process 900 of Fig. 9, process 1000 of Fig. 10, and/or other processes as described herein. The memory 242 and the memory 282 may store data and program codes for the network node 110 and the UE 120, respectively. In some examples, the memory 242 and/or the memory 282 may include a non-transitory computer-readable medium storing one or more instructions (e.g., code and/or program code) for wireless communication. For example, the one or more instructions, when executed (e.g., directly, or after compiling, converting, and/or interpreting) by one or more processors of the network node 110 and/or the UE 120, may cause the one or more processors, the UE 120, and/or the network node 110 to perform or direct operations of, for example, process 700 of Fig. 7, process 800 of Fig. 8, process 900 of Fig. 9, process 1000 of Fig. 10, and/or other processes as described herein. In some examples, executing instructions may include running the instructions, converting the instructions, compiling the instructions, and/or interpreting the instructions, among other examples.

In some aspects, a UE (e.g., the UE 120 and/or apparatus 1100 of Fig. 11) may include means for receiving a TA indication associated with a candidate serving cell configured for L1/L2 mobility; means for receiving, after or with the TA indication, an L1 message or an L2 message instructing the UE to switch to the candidate serving cell; and/or means for communicating with the candidate serving cell based on the L1 message or the L2 message. Alternatively, the UE may include means for receiving an L1 message or an L2 message instructing the UE to switch to a candidate serving cell; means for receiving, after the L1 message or the L2 message, a TA indication associated with the candidate serving cell; and/or means for communicating with the candidate serving cell based on the TA indication. The means for the UE to perform operations described herein may include, for example, one or more of communication manager 140, antenna 252, modem 254, MIMO detector 256, receive processor 258, transmit processor 264, TX MIMO processor 266, controller/processor 280, or memory 282.

In some aspects, a network node (e.g., the network node 110, an RU 340, a DU 330, a CU 310, and/or apparatus 1200 of Fig. 12) may include means for transmitting a TA indication associated with a candidate serving cell configured for L1/L2 mobility; and/or means for transmitting, after or with the TA indication, an L1 message or an L2 message instructing a UE to switch to the candidate serving cell. Alternatively, the network node may include means for transmitting a TA indication associated with a candidate serving cell configured for L1/L2 mobility after an L1 message or an L2 message instructing a UE to switch to the candidate serving cell; and/or means for communicating with the UE based on the TA indication. The means for the network node to perform operations described herein may include, for example, one or more of communication manager 150, transmit processor 220, TX MIMO processor 230, modem 232, antenna 234, MIMO detector 236, receive processor 238, controller/processor 240, memory 242, or scheduler 246.

While blocks in Fig. 2 are illustrated as distinct components, the functions described above with respect to the blocks may be implemented in a single hardware, software, or combination component or in various combinations of components. For example, the functions described with respect to the transmit processor 264, the receive processor 258, and/or the TX MIMO processor 266 may be performed by or under the control of the controller/processor 280.

As indicated above, Fig. 2 is provided as an example. Other examples may differ from what is described with regard to Fig. 2.

Deployment of communication systems, such as 5G NR systems, may be arranged in multiple manners with various components or constituent parts. In a 5G NR system, or network, a network node, a network entity, a mobility element of a network, a RAN node, a core network node, a network element, a base station, or a network equipment may be implemented in an aggregated or disaggregated architecture. For example, a base station (such as a Node B (NB) , an evolved NB (eNB) , an NR base station, a 5G NB, an access point (AP) , a TRP, or a cell, among other examples) , or one or more units (or one or more components) performing base station functionality, may be implemented as an aggregated base station (also known as a standalone base station or a monolithic base station) or a disaggregated base station. “Network entity” or “network node” may refer to a disaggregated base station, or to one or more units of a disaggregated base station (such as one or more CUs, one or more DUs, one or more RUs, or a combination thereof) .

An aggregated base station (e.g., an aggregated network node) may be configured to utilize a radio protocol stack that is physically or logically integrated within a single RAN node (e.g., within a single device or unit) . A disaggregated base station (e.g., a disaggregated network node) may be configured to utilize a protocol stack that is physically or logically distributed among two or more units (such as one or more CUs, one or more DUs, or one or more RUs) . In some examples, a CU may be implemented within a network node, and one or more DUs may be co-located with the CU, or alternatively, may be geographically or virtually distributed throughout one or multiple other network nodes. The DUs may be implemented to communicate with one or more RUs. Each of the CU, DU, and RU also can be implemented as virtual units, such as a virtual central unit (VCU) , a virtual distributed unit (VDU) , or a virtual radio unit (VRU) , among other examples.

Base station-type operation or network design may consider aggregation characteristics of base station functionality. For example, disaggregated base stations may be utilized in an IAB network, an open radio access network (O-RAN (such as the network configuration sponsored by the O-RAN Alliance) ) , or a virtualized radio access network (vRAN, also known as a cloud radio access network (C-RAN) ) to facilitate scaling of communication systems by separating base station functionality into one or more units that can be individually deployed. A disaggregated base station may include functionality implemented across two or more units at various physical locations, as well as functionality implemented for at least one unit virtually, which can enable flexibility in network design. The various units of the disaggregated base station can be configured for wired or wireless communication with at least one other unit of the disaggregated base station.

Fig. 3 is a diagram illustrating an example disaggregated base station architecture 300, in accordance with the present disclosure. The disaggregated base station architecture 300 may include a CU 310 that can communicate directly with a core network 320 via a backhaul link, or indirectly with the core network 320 through one or more disaggregated control units (such as a Near-RT RIC 325 via an E2 link, or a Non-RT RIC 315 associated with a Service Management and Orchestration (SMO) Framework 305, or both) . A CU 310 may communicate with one or more DUs 330 via respective midhaul links, such as through F1 interfaces. Each of the DUs 330 may communicate with one or more RUs 340 via respective fronthaul links. Each of the RUs 340 may communicate with one or more UEs 120 via respective radio frequency (RF) access links. In some implementations, a UE 120 may be simultaneously served by multiple RUs 340.

Each of the units, including the CUs 310, the DUs 330, the RUs 340, as well as the Near-RT RICs 325, the Non-RT RICs 315, and the SMO Framework 305, may include one or more interfaces or be coupled with one or more interfaces configured to receive or transmit signals, data, or information (collectively, signals) via a wired or wireless transmission medium. Each of the units, or an associated processor or controller providing instructions to one or multiple communication interfaces of the respective unit, can be configured to communicate with one or more of the other units via the transmission medium. In some examples, each of the units can include a wired interface, configured to receive or transmit signals over a wired transmission medium to one or more of the other units, and a wireless interface, which may include a receiver, a transmitter or transceiver (such as an RF transceiver) , configured to receive or transmit signals, or both, over a wireless transmission medium to one or more of the other units.

In some aspects, the CU 310 may host one or more higher layer control functions. Such control functions can include radio resource control (RRC) functions, packet data convergence protocol (PDCP) functions, or service data adaptation protocol (SDAP) functions, among other examples. Each control function can be implemented with an interface configured to communicate signals with other control functions hosted by the CU 310. The CU 310 may be configured to handle user plane functionality (for example, Central Unit –User Plane (CU-UP) functionality) , control plane functionality (for example, Central Unit –Control Plane (CU-CP) functionality) , or a combination thereof. In some implementations, the CU 310 can be logically split into one or more CU-UP units and one or more CU-CP units. A CU-UP unit can communicate bidirectionally with a CU-CP unit via an interface, such as the E1 interface when implemented in an O-RAN configuration. The CU 310 can be implemented to communicate with a DU 330, as necessary, for network control and signaling.

Each DU 330 may correspond to a logical unit that includes one or more base station functions to control the operation of one or more RUs 340. In some aspects, the DU 330 may host one or more of a radio link control (RLC) layer, a medium access control (MAC) layer, and one or more high physical (PHY) layers depending, at least in part, on a functional split, such as a functional split defined by the 3GPP. In some aspects, the one or more high PHY layers may be implemented by one or more modules for forward error correction (FEC) encoding and decoding, scrambling, and modulation and demodulation, among other examples. In some aspects, the DU 330 may further host one or more low PHY layers, such as implemented by one or more modules for a fast Fourier transform (FFT) , an inverse FFT (iFFT) , digital beamforming, or physical random access channel (PRACH) extraction and filtering, among other examples. Each layer (which also may be referred to as a module) can be implemented with an interface configured to communicate signals with other layers (and modules) hosted by the DU 330, or with the control functions hosted by the CU 310.

Each RU 340 may implement lower-layer functionality. In some deployments, an RU 340, controlled by a DU 330, may correspond to a logical node that hosts RF processing functions or low-PHY layer functions, such as performing an FFT, performing an iFFT, digital beamforming, or PRACH extraction and filtering, among other examples, based on a functional split (for example, a functional split defined by the 3GPP) , such as a lower layer functional split. In such an architecture, each RU 340 can be operated to handle over the air (OTA) communication with one or more UEs 120. In some implementations, real-time and non-real-time aspects of control and user plane communication with the RU (s) 340 can be controlled by the corresponding DU 330. In some scenarios, this configuration can enable each DU 330 and the CU 310 to be implemented in a cloud-based RAN architecture, such as a vRAN architecture.

The SMO Framework 305 may be configured to support RAN deployment and provisioning of non-virtualized and virtualized network elements. For non-virtualized network elements, the SMO Framework 305 may be configured to support the deployment of dedicated physical resources for RAN coverage requirements, which may be managed via an operations and maintenance interface (such as an O1 interface) . For virtualized network elements, the SMO Framework 305 may be configured to interact with a cloud computing platform (such as an open cloud (O-Cloud) platform 390) to perform network element life cycle management (such as to instantiate virtualized network elements) via a cloud computing platform interface (such as an O2 interface) . Such virtualized network elements can include, but are not limited to, CUs 310, DUs 330, RUs 340, non-RT RICs 315, and Near-RT RICs 325. In some implementations, the SMO Framework 305 can communicate with a hardware aspect of a 4G RAN, such as an open eNB (O-eNB) 311, via an O1 interface. Additionally, in some implementations, the SMO Framework 305 can communicate directly with each of one or more RUs 340 via a respective O1 interface. The SMO Framework 305 also may include a Non-RT RIC 315 configured to support functionality of the SMO Framework 305.

The Non-RT RIC 315 may be configured to include a logical function that enables non-real-time control and optimization of RAN elements and resources, Artificial Intelligence/Machine Learning (AI/ML) workflows including model training and updates, or policy-based guidance of applications/features in the Near-RT RIC 325. The Non-RT RIC 315 may be coupled to or communicate with (such as via an A1 interface) the Near-RT RIC 325. The Near-RT RIC 325 may be configured to include a logical function that enables near-real-time control and optimization of RAN elements and resources via data collection and actions over an interface (such as via an E2 interface) connecting one or more CUs 310, one or more DUs 330, or both, as well as an O-eNB, with the Near-RT RIC 325.

In some implementations, to generate AI/ML models to be deployed in the Near-RT RIC 325, the Non-RT RIC 315 may receive parameters or external enrichment information from external servers. Such information may be utilized by the Near-RT RIC 325 and may be received at the SMO Framework 305 or the Non-RT RIC 315 from non-network data sources or from network functions. In some examples, the Non-RT RIC 315 or the Near-RT RIC 325 may be configured to tune RAN behavior or performance. For example, the Non-RT RIC 315 may monitor long-term trends and patterns for performance and employ AI/ML models to perform corrective actions through the SMO Framework 305 (such as reconfiguration via an O1 interface) or via creation of RAN management policies (such as A1 interface policies) .

As indicated above, Fig. 3 is provided as an example. Other examples may differ from what is described with regard to Fig. 3.

Fig. 4 is a diagram illustrating an example 400 of TAs for active and candidate serving cells, in accordance with the present disclosure. In example 400, a network may configure a UE (e.g., UE 120) with different sets of cells. Each cell may include one TRP or a group of TRPs. Additionally, or alternatively, multiple TRPs within a cell may be configured separately (e.g., for non-coherent joint transmission (NCJT) ) or together (e.g., for coherent joint transmission (CJT) ) .

As shown in Fig. 4, the network may communicate with the UE 120 via an active serving cell 102a. The active serving cell 102a may include at least one TRP. As further shown in Fig. 4, the network may provide the UE 120 with a set of cells for L1/L2 mobility. As used herein, “layer 1” or “L1” refers to a PHY layer, “layer 2” or “L2” refers to a MAC layer, an RLC layer, a PDCP layer, and/or an SDAP layer, and “layer 1/layer 2” or “L1/L2” refers to layer 1 and/or layer 2. The network may indicate the set of cells in an RRC message including an l1l2MobilityConfig data structure (e.g., as defined in 3GPP specifications and/or another standard) . In example 400, the set of cells includes a candidate serving cell 102b and a candidate serving cell 102c (e.g., each including at least one TRP) . Other examples may include one candidate serving cell or additional candidate serving cells (e.g., three candidate serving cells, four candidate serving cells, and so on) .

Each serving cell may be associated with a timing advance group (TAG) . For example, the active serving cell 102a may be associated with a first TAG, the candidate serving cell 102b may be associated with a second TAG, and the candidate serving cell 102c may be associated with a third TAG. Accordingly, in example 400, the active serving cell 102a, the candidate serving cell 102b, and the candidate serving cell 102c may transmit different TA commands (e.g., corresponding to the different TAGs) . Although example 400 is described with one cell in each TAG, other examples may include multiple cells in a TAG. Additionally, or alternatively, although example 400 is described with one TAG per cell, other examples may include multiple TAGs associated with a single cell. For example, a cell may include multiple TRPs, where each TRP is associated with a different TAG.

In order to reduce latency when a UE is moving (and/or when channel conditions are changing) , an active serving cell may instruct the UE to switch to a candidate serving cell using an L1 message (e.g., downlink control information (DCI) ) or an L2 message (e.g., a MAC control element (MAC-CE) ) . However, when the candidate serving cell is in a different TAG than the active serving cell, the UE will experience reduced quality and reliability when communicating with the candidate serving cell. As a result, the UE may waste power and processing resources because the candidate serving cell is less likely to receive and decode uplink transmissions from the UE, resulting in more retransmissions.

Some techniques and apparatuses described herein enable a UE (e.g., UE 120) to receive a TA indication, associated with a candidate serving cell configured for L1/L2 mobility, before an L1 message or an L2 message instructing the UE 120 to switch to the candidate serving cell. For example, the UE 120 may apply a TA management procedure (e.g., including TA acquisition and receiving the TA indication) before following an L1/L2 cell switch command when the candidate cell is a deactivated cell. As a result, the UE 120 may perform a timing adjustment before communicating with the candidate serving cell. Therefore, the UE 120 experiences reduced latency because the UE 120 can begin communicating with the candidate serving cell immediately after switching. Additionally, the UE 120 experiences increased reliability and quality of communications, which conserves power and processing resources that would otherwise have been expended on retransmissions.

Alternatively, some techniques and apparatuses described herein enable a UE (e.g., UE 120) to receive a TA indication, associated with a candidate serving cell configured for L1/L2 mobility, with an L1 message or an L2 message instructing the UE 120 to switch to the candidate serving cell. As a result, the UE 120 may perform a timing adjustment during a handover procedure to the candidate serving cell. For example, the UE 120 may trigger a sound reference signal (SRS) transmission to refine a TA for the candidate serving cell when receiving an L1/L2 cell switch command indicating handover to the candidate serving cell. The UE 120 may apply a TA value either indicated in the L1/L2 cell switch command or derived as an initial TA value for the triggered SRS transmission.

Alternatively, some techniques and apparatuses described herein enable a UE (e.g., UE 120) to receive a TA indication, associated with a candidate serving cell configured for L1/L2 mobility, after an L1 message or an L2 message instructing the UE 120 to switch to the candidate serving cell. As a result, the UE 120 may perform a timing adjustment after switching to the candidate serving cell. Because the candidate serving cell provides the TA indication, the active serving cell conserves power and processing resources that would otherwise have been expended on backhaul communications to determine a TA value associated with the candidate serving cell. Additionally, the UE 120 experiences increased reliability and quality of communications, which conserves power and processing resources that would otherwise have been expended on retransmissions.

As indicated above, Fig. 4 is provided as an example. Other examples may differ from what is described with respect to Fig. 4.

Fig. 5 is a diagram illustrating an example 500 associated with providing TA indications before or with an instruction to switch to a candidate serving cell, in accordance with the present disclosure. As shown in Fig. 5, a network node 110 (e.g., an RU 340 and/or a device controlling the RU 340, such as a DU 330 and/or a CU 310) and a UE 120 may communicate with one another (e.g., on a wireless network, such as wireless network 100 of Fig. 1) . Some examples may include a plurality of network nodes 110 (e.g., throughout the wireless network 100) . In example 500, the network node (s) 110 may represent an active serving cell associated with the UE 120, where the active serving cell may include at least one TRP, as described in connection with Fig. 4.

In some aspects, as shown by reference number 505, the network node (s) 110 may transmit (e.g., directly or via the RU 340) , and the UE 120 may receive, a random access channel (RACH) trigger and/or an SRS trigger. Accordingly, the UE 120 may transmit a RACH preamble or an SRS to the candidate serving cell based on the RACH trigger or the SRS trigger for TA acquisition in the candidate serving cell. For example, the RACH or SRS transmission may be configured on the candidate serving cell when the candidate serving cell is deactivated, and the network node (s) 110 may transmit the RACH trigger and/or the SRS trigger to trigger the RACH or SRS transmission on the candidate serving cell before an L1/L2 cell switch command to the candidate serving cell. In another example, the network node (s) 110 may transmit the RACH trigger and/or the SRS trigger in the L1/L2 cell switch command to trigger PRACH or SRS transmission as part of a handover procedure to the candidate serving cell configured for L1/L2 mobility (e.g., as described in connection with Fig. 4) .

As shown by reference number 510, the network node (s) 110 may transmit (e.g., directly or via the RU 340) , and the UE 120 may receive, a TA indication associated with the candidate serving cell. For example, the TA indication may be included in a MAC-CE.

The TA indication may include a TA identifier associated with a TAG that includes the candidate serving cell. For example, the TA identifier may be a TAG identity (TAG ID) or another type of identifier associated with the TAG. In one example, the TAG may be associated with a transmission configuration indicator (TCI) state associated with the candidate serving cell. Accordingly, the UE 120 applies a TA value indicated in the TA indication when using the TCI state. In another example, the TAG may be associated with at least one reference signal (e.g., an SRS or another type of reference signal) associated with the candidate serving cell. Accordingly, the UE 120 applies a TA value indicated in the TA indication when transmitting the at least one reference signal. In another example, the TAG associated with the candidate serving cell may be a primary TAG. Accordingly, the UE 120 applies a TA value indicated in the TA indication when communicating with the candidate serving cell.

As shown by reference number 515, the UE 120 may perform a timing adjustment based on the TA indication. For example, the UE 120 may apply a TA value indicated in the TA indication, as described above. Because the UE 120 received the TA indication before switching to the candidate serving cell, the UE 120 performs the timing adjustment before communicating with the candidate serving cell.

As shown by reference number 520, the network node (s) 110 may transmit (e.g., directly or via the RU 340) , and the UE 120 may receive, an L1 message or an L2 message instructing the UE 120 to switch to the candidate serving cell. For example, the L2 message may be a MAC-CE, and the L1 message may be DCI.

In some aspects, the network node (s) 110 may transmit a handover command (e.g., after transmitting the RACH trigger or the SRS trigger) . The handover command may be included in the L1 message or the L2 message. Therefore, the UE 120 may receive the TA indication before the handover command.

Alternatively, the network node (s) 110 may include the TA indication in the L1 message or the L2 message. In some aspects, the TA indication may thus be included in the handover command. The UE 120 may still perform the timing adjustment before communicating with the candidate serving cell because the TA indication is received in the L1 message or the L2 message.

By using techniques as described in connection with Fig. 5, the UE 120 receives the TA indication, associated with the candidate serving cell configured for L1/L2 mobility, before or with the L1 message or the L2 message instructing the UE 120 to switch to the candidate serving cell. As a result, the UE 120 may perform a timing adjustment before communicating with the candidate serving cell. Therefore, the UE 120 experiences reduced latency because the UE 120 can begin communicating with the candidate serving cell immediately after switching. Additionally, the UE 120 experiences increased reliability and quality of communications, which conserves power and processing resources that would otherwise have been expended on retransmissions.

As indicated above, Fig. 5 is provided as an example. Other examples may differ from what is described with respect to Fig. 5.

Fig. 6 is a diagram illustrating an example 600 associated with providing TA indications after an instruction to switch to a candidate serving cell, in accordance with the present disclosure. As shown in Fig. 6, a network node 110 (e.g., an RU 340 and/or a device controlling the RU 340, such as a DU 330 and/or a CU 310) and a UE 120 may communicate with one another (e.g., on a wireless network, such as wireless network 100 of Fig. 1) . Some examples may include a plurality of network nodes 110 (e.g., throughout the wireless network 100) . In example 600, the network node (s) 110 may represent a candidate serving cell associated with the UE 120, where the candidate serving cell may include at least one TRP, as described in connection with Fig. 4.

In some aspects, as shown by reference number 605, the UE 120 may transmit, and the network node (s) 110 may receive (e.g., directly or via the RU 340) , a RACH preamble and/or an SRS. For example, an active serving cell may transmit a RACH trigger and/or an SRS trigger to the UE 120 (e.g., as described in connection with reference number 505 of Fig. 5) such that the UE 120 transmits the RACH preamble and/or the SRS based on the RACH trigger and/or the SRS trigger.

The UE 120 may switch to the candidate serving cell. For example, the active serving cell may transmit an L1 message or an L2 message to the UE 120 (e.g., as described in connection with reference number 520 of Fig. 5) such that the UE 120 switches to the candidate serving cell. In some aspects, L1 message or the L2 message may include a handover command.

As shown by reference number 610, the network node (s) 110 may transmit (e.g., directly or via the RU 340) , and the UE 120 may receive, a TA indication associated with the candidate serving cell. For example, the TA indication may be included in a MAC-CE. The TA indication may include a TA identifier associated with a TAG that includes the candidate serving cell. For example, the TA identifier may be a TAG ID or another type of identifier associated with the TAG.

As shown by reference number 615, the UE 120 may perform a timing adjustment based on the TA indication. For example, the UE 120 may apply a TA value indicated in the TA indication. Because the UE 120 received the TA indication after switching to the candidate serving cell, the UE 120 performs the timing adjustment after switching. Additionally, the UE 120 may perform the timing adjustment before communicating with the candidate serving cell.

As shown by reference number 620, the UE 120 may communicate with the network node (s) 110 (e.g., directly or via the RU 340) . For example, the UE 120 may transmit an uplink transmission to the network node (s) 110 based on the TA indication (e.g., by applying the TA value indicated in the TA indication) .

By using techniques as described in connection with Fig. 6, the UE 120 may receive the TA indication after the L1 message or the L2 message instructing the UE 120 to switch to the candidate serving cell. As a result, the UE 120 may perform a timing adjustment after switching to the candidate serving cell. Because the candidate serving cell provides the TA indication, the active serving cell conserves power and processing resources that would otherwise have been expended on backhaul communications to determine a TA value associated with the candidate serving cell. Additionally, the UE 120 experiences increased reliability and quality of communications, which conserves power and processing resources that would otherwise have been expended on retransmissions.

As indicated above, Fig. 6 is provided as an example. Other examples may differ from what is described with respect to Fig. 6.

Fig. 7 is a diagram illustrating an example process 700 performed, for example, by a UE, in accordance with the present disclosure. Example process 700 is an example where the UE (e.g., UE 120 and/or apparatus 1100 of Fig. 11) performs operations associated with TA indications for candidate serving cells.

As shown in Fig. 7, in some aspects, process 700 may include receiving a TA indication associated with a candidate serving cell configured for L1/L2 mobility (block 710) . For example, the UE (e.g., using communication manager 140 and/or reception component 1102, depicted in Fig. 11) may receive a TA indication associated with a candidate serving cell configured for L1/L2 mobility, as described herein.

As further shown in Fig. 7, in some aspects, process 700 may include receiving, after or with the TA indication, an L1 message or an L2 message instructing a switch to the candidate serving cell (block 720) . For example, the UE (e.g., using communication manager 140 and/or reception component 1102) may receive, after or with the TA indication, an L1 message or an L2 message instructing a switch to the candidate serving cell, as described herein.

As further shown in Fig. 7, in some aspects, process 700 may include communicating with the candidate serving cell based on the L1 message or the L2 message (block 730) . For example, the UE (e.g., using communication manager 140, reception component 1102, and/or transmission component 1104, depicted in Fig. 11) may communicate with the candidate serving cell based on the L1 message or the L2 message, as described herein.

Process 700 may include additional aspects, such as any single aspect or any combination of aspects described below and/or in connection with one or more other processes described elsewhere herein.

In a first aspect, the TA indication comprises a MAC-CE.

In a second aspect, alone or in combination with the first aspect, the L2 message comprises a MAC-CE.

In a third aspect, alone or in combination with one or more of the first and second aspects, the L1 message comprises DCI.

In a fourth aspect, alone or in combination with one or more of the first through third aspects, process 700 includes receiving (e.g., using communication manager 140 and/or reception component 1102) a RACH trigger or an SRS trigger, transmitting (e.g., using communication manager 140 and/or transmission component 1104) a RACH preamble or an SRS to the candidate serving cell based on the RACH trigger or the SRS trigger, and receiving (e.g., using communication manager 140 and/or reception component 1102) a handover command after transmitting the RACH preamble or the SRS.

In a fifth aspect, alone or in combination with one or more of the first through fourth aspects, the TA indication is received before the handover command.

In a sixth aspect, alone or in combination with one or more of the first through fifth aspects, the TA indication is included in the handover command.

In a seventh aspect, alone or in combination with one or more of the first through sixth aspects, the TA indication includes a TA identifier associated with a TAG that includes the candidate serving cell.

In an eighth aspect, alone or in combination with one or more of the first through seventh aspects, the TAG is associated with a TCI state associated with the candidate serving cell.

In a ninth aspect, alone or in combination with one or more of the first through eighth aspects, the TAG is associated with at least one reference signal associated with the candidate serving cell.

In a tenth aspect, alone or in combination with one or more of the first through ninth aspects, the TAG is a primary TAG associated with the candidate serving cell.

Although Fig. 7 shows example blocks of process 700, in some aspects, process 700 may include additional blocks, fewer blocks, different blocks, or differently arranged blocks than those depicted in Fig. 7. Additionally, or alternatively, two or more of the blocks of process 700 may be performed in parallel.

Fig. 8 is a diagram illustrating an example process 800 performed, for example, by a network node, in accordance with the present disclosure. Example process 800 is an example where the network node (e.g., network node 110 and/or apparatus 1200 of Fig. 12) performs operations associated with TA indications for candidate serving cells.

As shown in Fig. 8, in some aspects, process 800 may include transmitting a TA indication associated with a candidate serving cell configured for L1/L2 mobility (block 810) . For example, the network node (e.g., using communication manager 150 and/or transmission component 1204, depicted in Fig. 12) may transmit a TA indication associated with a candidate serving cell configured for L1/L2 mobility, as described herein.

As further shown in Fig. 8, in some aspects, process 800 may include transmitting, after or with the TA indication, an L1 message or an L2 message instructing a switch to the candidate serving cell (block 820) . For example, the network node (e.g., using communication manager 150 and/or transmission component 1204) may transmit, after or with the TA indication, an L1 message or an L2 message instructing a switch to the candidate serving cell, as described herein.

Process 800 may include additional aspects, such as any single aspect or any combination of aspects described below and/or in connection with one or more other processes described elsewhere herein.

In a first aspect, the TA indication comprises a MAC-CE.

In a fourth aspect, alone or in combination with one or more of the first through third aspects, process 800 includes transmitting (e.g., using communication manager 150 and/or transmission component 1204) a RACH trigger or an SRS trigger, and transmitting (e.g., using communication manager 150 and/or transmission component 1204) a handover command after transmitting the RACH trigger or the SRS trigger.

Although Fig. 8 shows example blocks of process 800, in some aspects, process 800 may include additional blocks, fewer blocks, different blocks, or differently arranged blocks than those depicted in Fig. 8. Additionally, or alternatively, two or more of the blocks of process 800 may be performed in parallel.

Fig. 9 is a diagram illustrating an example process 900 performed, for example, by a UE, in accordance with the present disclosure. Example process 900 is an example where the UE (e.g., UE 120 and/or apparatus 1100 of Fig. 11) performs operations associated with TA indications for candidate serving cells.

As shown in Fig. 9, in some aspects, process 900 may include receiving an L1 message or an L2 message instructing a switch to a candidate serving cell (block 910) . For example, the UE (e.g., using communication manager 140 and/or reception component 1102, depicted in Fig. 11) may receive an L1 message or an L2 message instructing a switch to a candidate serving cell, as described herein.

As further shown in Fig. 9, in some aspects, process 900 may include receiving, after the L1 message or the L2 message, a TA indication associated with the candidate serving cell (block 920) . For example, the UE (e.g., using communication manager 140 and/or reception component 1102) may receive, after the L1 message or the L2 message, a TA indication associated with the candidate serving cell, as described herein.

As further shown in Fig. 9, in some aspects, process 900 may include communicating with the candidate serving cell based on the TA indication (block 930) . For example, the UE (e.g., using communication manager 140, reception component 1102, and/or transmission component 1104, depicted in Fig. 11) may communicate with the candidate serving cell based on the TA indication, as described herein.

Process 900 may include additional aspects, such as any single aspect or any combination of aspects described below and/or in connection with one or more other processes described elsewhere herein.

In a first aspect, the TA indication comprises a MAC-CE.

In a fourth aspect, alone or in combination with one or more of the first through third aspects, the TA indication includes a TA identifier associated with a TAG that includes the candidate serving cell.

Although Fig. 9 shows example blocks of process 900, in some aspects, process 900 may include additional blocks, fewer blocks, different blocks, or differently arranged blocks than those depicted in Fig. 9. Additionally, or alternatively, two or more of the blocks of process 900 may be performed in parallel.

Fig. 10 is a diagram illustrating an example process 1000 performed, for example, by a network node, in accordance with the present disclosure. Example process 1000 is an example where the network node (e.g., network node 110 and/or apparatus 1200 of Fig. 12) performs operations associated with TA indications for candidate serving cells.

As shown in Fig. 10, in some aspects, process 1000 may include transmitting a TA indication associated with a candidate serving cell configured for L1/L2 mobility after an L1 message or an L2 message instructing a switch to the candidate serving cell (block 1010) . For example, the network node (e.g., using communication manager 150 and/or transmission component 1204, depicted in Fig. 12) may transmit a TA indication associated with a candidate serving cell configured for L1/L2 mobility after an L1 message or an L2 message instructing a switch to the candidate serving cell, as described herein.

As further shown in Fig. 10, in some aspects, process 1000 may include communicating with a UE based on the TA indication (block 1020) . For example, the network node (e.g., using communication manager 150, reception component 1202, and/or transmission component 1204, depicted in Fig. 12) may communicate with a UE based on the TA indication, as described herein.

Process 1000 may include additional aspects, such as any single aspect or any combination of aspects described below and/or in connection with one or more other processes described elsewhere herein.

In a first aspect, the TA indication comprises a MAC-CE.

Although Fig. 10 shows example blocks of process 1000, in some aspects, process 1000 may include additional blocks, fewer blocks, different blocks, or differently arranged blocks than those depicted in Fig. 10. Additionally, or alternatively, two or more of the blocks of process 1000 may be performed in parallel.

Fig. 11 is a diagram of an example apparatus 1100 for wireless communication, in accordance with the present disclosure. The apparatus 1100 may be a UE, or a UE may include the apparatus 1100. In some aspects, the apparatus 1100 includes a reception component 1102 and a transmission component 1104, which may be in communication with one another (for example, via one or more buses and/or one or more other components) . As shown, the apparatus 1100 may communicate with another apparatus 1106 (such as a UE, an RU, or another wireless communication device) using the reception component 1102 and the transmission component 1104. As further shown, the apparatus 1100 may include the communication manager 140. The communication manager 140 may include a TA component 1108, among other examples.

In some aspects, the apparatus 1100 may be configured to perform one or more operations described herein in connection with Figs. 5-6. Additionally, or alternatively, the apparatus 1100 may be configured to perform one or more processes described herein, such as process 700 of Fig. 7, process 900 of Fig. 9, or a combination thereof. In some aspects, the apparatus 1100 and/or one or more components shown in Fig. 11 may include one or more components of the UE described in connection with Fig. 2. Additionally, or alternatively, one or more components shown in Fig. 11 may be implemented within one or more components described in connection with Fig. 2. Additionally, or alternatively, one or more components of the set of components may be implemented at least in part as software stored in a memory. For example, a component (or a portion of a component) may be implemented as instructions or code stored in a non-transitory computer-readable medium and executable by a controller or a processor to perform the functions or operations of the component.

The reception component 1102 may receive communications, such as reference signals, control information, data communications, or a combination thereof, from the apparatus 1106. The reception component 1102 may provide received communications to one or more other components of the apparatus 1100. In some aspects, the reception component 1102 may perform signal processing on the received communications (such as filtering, amplification, demodulation, analog-to-digital conversion, demultiplexing, deinterleaving, de-mapping, equalization, interference cancellation, or decoding, among other examples) , and may provide the processed signals to the one or more other components of the apparatus 1100. In some aspects, the reception component 1102 may include one or more antennas, a modem, a demodulator, a MIMO detector, a receive processor, a controller/processor, a memory, or a combination thereof, of the UE described in connection with Fig. 2.

The transmission component 1104 may transmit communications, such as reference signals, control information, data communications, or a combination thereof, to the apparatus 1106. In some aspects, one or more other components of the apparatus 1100 may generate communications and may provide the generated communications to the transmission component 1104 for transmission to the apparatus 1106. In some aspects, the transmission component 1104 may perform signal processing on the generated communications (such as filtering, amplification, modulation, digital-to- analog conversion, multiplexing, interleaving, mapping, or encoding, among other examples) , and may transmit the processed signals to the apparatus 1106. In some aspects, the transmission component 1104 may include one or more antennas, a modem, a modulator, a transmit MIMO processor, a transmit processor, a controller/processor, a memory, or a combination thereof, of the UE described in connection with Fig. 2. In some aspects, the transmission component 1104 may be co-located with the reception component 1102 in a transceiver.

In some aspects, the reception component 1102 may receive (e.g., from the apparatus 1106) a TA indication associated with a candidate serving cell configured for L1/L2 mobility. The TA component 1108 may thus perform a timing adjustment based on the TA indication. The TA component 1108 may include one or more antennas, a modem, a demodulator, a MIMO detector, a receive processor, a modulator, a transmit MIMO processor, a transmit processor, a controller/processor, a memory, or a combination thereof, of the UE described in connection with Fig. 2. Additionally, the reception component 1102 may receive, after or with the TA indication, an L1 message or an L2 message instructing the apparatus 1100 to switch to the candidate serving cell. Accordingly, the reception component 1102 and/or the transmission component 1104 may communicate with the candidate serving cell based on the L1 message or the L2 message.

In some aspects, the reception component 1102 may receive (e.g., from the apparatus 1106) a RACH trigger or an SRS trigger. Accordingly, the transmission component 1104 may transmit a RACH preamble or an SRS to the candidate serving cell based on the RACH trigger or the SRS trigger. Therefore, the reception component 1102 may receive a handover command after transmitting the RACH preamble or the SRS, and the TA indication may be received before or with the handover command.

Alternatively, the reception component 1102 may receive (e.g., from the apparatus 1106) an L1 message or an L2 message instructing the UE to switch to a candidate serving cell. The reception component 1102 may further receive, after the L1 message or the L2 message, a TA indication associated with the candidate serving cell. Accordingly, the reception component 1102 and/or the transmission component 1104 may communicate with the candidate serving cell based on the TA indication. Additionally, the TA component 1108 may thus perform a timing adjustment based on the TA indication.

The number and arrangement of components shown in Fig. 11 are provided as an example. In practice, there may be additional components, fewer components, different components, or differently arranged components than those shown in Fig. 11. Furthermore, two or more components shown in Fig. 11 may be implemented within a single component, or a single component shown in Fig. 11 may be implemented as multiple, distributed components. Additionally, or alternatively, a set of (one or more) components shown in Fig. 11 may perform one or more functions described as being performed by another set of components shown in Fig. 11.

Fig. 12 is a diagram of an example apparatus 1200 for wireless communication, in accordance with the present disclosure. The apparatus 1200 may be a network node, or a network node may include the apparatus 1200. In some aspects, the apparatus 1200 includes a reception component 1202 and a transmission component 1204, which may be in communication with one another (for example, via one or more buses and/or one or more other components) . As shown, the apparatus 1200 may communicate with another apparatus 1206 (such as a UE, an RU, or another wireless communication device) using the reception component 1202 and the transmission component 1204. As further shown, the apparatus 1200 may include the communication manager 150. The communication manager 150 may include a handover component 1208, among other examples.

In some aspects, the apparatus 1200 may be configured to perform one or more operations described herein in connection with Figs. 5-6. Additionally, or alternatively, the apparatus 1200 may be configured to perform one or more processes described herein, such as process 800 of Fig. 8, process 1000 of Fig. 10, or a combination thereof. In some aspects, the apparatus 1200 and/or one or more components shown in Fig. 12 may include one or more components of the network node described in connection with Fig. 2. Additionally, or alternatively, one or more components shown in Fig. 12 may be implemented within one or more components described in connection with Fig. 2. Additionally, or alternatively, one or more components of the set of components may be implemented at least in part as software stored in a memory. For example, a component (or a portion of a component) may be implemented as instructions or code stored in a non-transitory computer-readable medium and executable by a controller or a processor to perform the functions or operations of the component.

The reception component 1202 may receive communications, such as reference signals, control information, data communications, or a combination thereof, from the apparatus 1206. The reception component 1202 may provide received communications to one or more other components of the apparatus 1200. In some aspects, the reception component 1202 may perform signal processing on the received communications (such as filtering, amplification, demodulation, analog-to-digital conversion, demultiplexing, deinterleaving, de-mapping, equalization, interference cancellation, or decoding, among other examples) , and may provide the processed signals to the one or more other components of the apparatus 1200. In some aspects, the reception component 1202 may include one or more antennas, a modem, a demodulator, a MIMO detector, a receive processor, a controller/processor, a memory, or a combination thereof, of the network node described in connection with Fig. 2.

The transmission component 1204 may transmit communications, such as reference signals, control information, data communications, or a combination thereof, to the apparatus 1206. In some aspects, one or more other components of the apparatus 1200 may generate communications and may provide the generated communications to the transmission component 1204 for transmission to the apparatus 1206. In some aspects, the transmission component 1204 may perform signal processing on the generated communications (such as filtering, amplification, modulation, digital-to-analog conversion, multiplexing, interleaving, mapping, or encoding, among other examples) , and may transmit the processed signals to the apparatus 1206. In some aspects, the transmission component 1204 may include one or more antennas, a modem, a modulator, a transmit MIMO processor, a transmit processor, a controller/processor, a memory, or a combination thereof, of the network node described in connection with Fig. 2. In some aspects, the transmission component 1204 may be co-located with the reception component 1202 in a transceiver.

In some aspects, the transmission component 1204 may transmit a TA indication associated with a candidate serving cell configured for L1/L2 mobility. Additionally, the transmission component 1204 may transmit, after or with the TA indication, an L1 message or an L2 message instructing a UE (e.g., the apparatus 1206) to switch to the candidate serving cell.

The apparatus 1200 may be associated with an active serving cell. Accordingly, the handover component 1208 may perform handover for the UE to the candidate serving cell. For example, the transmission component 1204 may transmit a RACH trigger or an SRS trigger. Additionally, the transmission component 1204 may transmit a handover command after transmitting the RACH trigger or the SRS trigger.

Alternatively, the transmission component 1204 may transmit a TA indication associated with a candidate serving cell configured for L1/L2 mobility after an L1 message or an L2 message instructing a UE (e.g., the apparatus 1206) to switch to the candidate serving cell. Accordingly, the reception component 1202 and/or the transmission component 1204 may communicate with the UE based on the TA indication.

The number and arrangement of components shown in Fig. 12 are provided as an example. In practice, there may be additional components, fewer components, different components, or differently arranged components than those shown in Fig. 12. Furthermore, two or more components shown in Fig. 12 may be implemented within a single component, or a single component shown in Fig. 12 may be implemented as multiple, distributed components. Additionally, or alternatively, a set of (one or more) components shown in Fig. 12 may perform one or more functions described as being performed by another set of components shown in Fig. 12.

The following provides an overview of some Aspects of the present disclosure:

Aspect 1: A method of wireless communication performed by a user equipment (UE) , comprising: receiving a timing advance (TA) indication associated with a candidate serving cell configured for layer 1/layer 2 (L1/L2) mobility; receiving, after or with the TA indication, an L1 message or an L2 message instructing the UE to switch to the candidate serving cell; and communicating with the candidate serving cell based on the L1 message or the L2 message.

Aspect 2: The method of Aspect 1, wherein the TA indication comprises a medium access control layer control element.

Aspect 3: The method of any of Aspects 1-2, wherein the L2 message comprises a medium access control layer control element.

Aspect 4: The method of any of Aspects 1-3, wherein the L1 message comprises downlink control information.

Aspect 5: The method of any of Aspects 1-4, further comprising: receiving a random access channel (RACH) trigger or a sounding reference signal (SRS) trigger; transmitting a RACH preamble or an SRS to the candidate serving cell based on the RACH trigger or the SRS trigger; and receiving a handover command after transmitting the RACH preamble or the SRS.

Aspect 6: The method of Aspect 5, wherein the TA indication is received before the handover command.

Aspect 7: The method of Aspect 5, wherein the TA indication is included in the handover command.

Aspect 8: The method of any of Aspects 1-7, wherein the TA indication includes a TA identifier associated with a TA group (TAG) that includes the candidate serving cell.

Aspect 9: The method of Aspect 8, wherein the TAG is associated with a transmission configuration indicator state associated with the candidate serving cell.

Aspect 10: The method of Aspect 8, wherein the TAG is associated with at least one reference signal associated with the candidate serving cell.

Aspect 11: The method of Aspect 8, wherein the TAG is a primary TAG associated with the candidate serving cell.

Aspect 12: A method of wireless communication performed by a network node, comprising: transmitting a timing advance (TA) indication associated with a candidate serving cell configured for layer 1/layer 2 (L1/L2) mobility; and transmitting, after or with the TA indication, an L1 message or an L2 message instructing a user equipment (UE) to switch to the candidate serving cell.

Aspect 13: The method of Aspect 12, wherein the TA indication comprises a medium access control layer control element.

Aspect 14: The method of any of Aspects 12-13, wherein the L2 message comprises a medium access control layer control element.

Aspect 15: The method of any of Aspects 12-14, wherein the L1 message comprises downlink control information.

Aspect 16: The method of any of Aspects 12-15, further comprising: transmitting a random access channel (RACH) trigger or a sounding reference signal (SRS) trigger; and transmitting a handover command after transmitting the RACH trigger or the SRS trigger.

Aspect 17: The method of Aspect 16, wherein the TA indication is received before the handover command.

Aspect 18: The method of Aspect 16, wherein the TA indication is included in the handover command.

Aspect 19: The method of any of Aspects 12-18, wherein the TA indication includes a TA identifier associated with a TA group (TAG) that includes the candidate serving cell.

Aspect 20: The method of Aspect 19, wherein the TAG is associated with a transmission configuration indicator state associated with the candidate serving cell.

Aspect 21: The method of Aspect 19, wherein the TAG is associated with at least one reference signal associated with the candidate serving cell.

Aspect 22: The method of Aspect 19, wherein the TAG is a primary TAG associated with the candidate serving cell.

Aspect 23: A method of wireless communication performed by a user equipment (UE) , comprising: receiving a layer 1 (L1) message or a layer 2 (L2) message instructing the UE to switch to a candidate serving cell; receiving, after the L1 message or the L2 message, a timing advance (TA) indication associated with the candidate serving cell; and communicating with the candidate serving cell based on the TA indication.

Aspect 24: The method of Aspect 23, wherein the TA indication comprises a medium access control layer control element.

Aspect 25: The method of any of Aspects 23-24, wherein the L2 message comprises a medium access control layer control element.

Aspect 26: The method of any of Aspects 23-25, wherein the L1 message comprises downlink control information.

Aspect 27: The method of any of Aspects 23-26, wherein the TA indication includes a TA identifier associated with a TA group (TAG) that includes the candidate serving cell.

Aspect 28: A method of wireless communication performed by a network node, comprising: transmitting a timing advance (TA) indication associated with a candidate serving cell configured for layer 1/layer 2 (L1/L2) mobility after an L1 message or an L2 message instructing a user equipment (UE) to switch to the candidate serving cell; and communicating with the UE based on the TA indication.

Aspect 29: The method of Aspect 28, wherein the TA indication comprises a medium access control layer control element.

Aspect 30: The method of any of Aspects 28-29, wherein the L2 message comprises a medium access control layer control element.

Aspect 31: The method of any of Aspects 28-30, wherein the L1 message comprises downlink control information.

Aspect 32: The method of any of Aspects 28-31, wherein the TA indication includes a TA identifier associated with a TA group (TAG) that includes the candidate serving cell.

Aspect 33: An apparatus for wireless communication at a device, comprising a processor; memory coupled with the processor; and instructions stored in the memory and executable by the processor to cause the apparatus to perform the method of one or more of Aspects 1-32.

Aspect 34: A device for wireless communication, comprising a memory and one or more processors coupled to the memory, the one or more processors configured to perform the method of one or more of Aspects 1-32.

Aspect 35: An apparatus for wireless communication, comprising at least one means for performing the method of one or more of Aspects 1-32.

Aspect 36: A non-transitory computer-readable medium storing code for wireless communication, the code comprising instructions executable by a processor to perform the method of one or more of Aspects 1-32.

Aspect 37: A non-transitory computer-readable medium storing a set of instructions for wireless communication, the set of instructions comprising one or more instructions that, when executed by one or more processors of a device, cause the device to perform the method of one or more of Aspects 1-32.

The foregoing disclosure provides illustration and description but is not intended to be exhaustive or to limit the aspects to the precise forms disclosed. Modifications and variations may be made in light of the above disclosure or may be acquired from practice of the aspects.

As used herein, the term “component” is intended to be broadly construed as hardware and/or a combination of hardware and software. “Software” shall be construed broadly to mean instructions, instruction sets, code, code segments, program code, programs, subprograms, software modules, applications, software applications, software packages, routines, subroutines, objects, executables, threads of execution, procedures, and/or functions, among other examples, whether referred to as software, firmware, middleware, microcode, hardware description language, or otherwise. As used herein, a “processor” is implemented in hardware and/or a combination of hardware and software. It will be apparent that systems and/or methods described herein may be implemented in different forms of hardware and/or a combination of hardware and software. The actual specialized control hardware or software code used to implement these systems and/or methods is not limiting of the aspects. Thus, the operation and behavior of the systems and/or methods are described herein without reference to specific software code, since those skilled in the art will understand that software and hardware can be designed to implement the systems and/or methods based, at least in part, on the description herein.

As used herein, “satisfying a threshold” may, depending on the context, refer to a value being greater than the threshold, greater than or equal to the threshold, less than the threshold, less than or equal to the threshold, equal to the threshold, not equal to the threshold, or the like.

Even though particular combinations of features are recited in the claims and/or disclosed in the specification, these combinations are not intended to limit the disclosure of various aspects. Many of these features may be combined in ways not specifically recited in the claims and/or disclosed in the specification. The disclosure of various aspects includes each dependent claim in combination with every other claim in the claim set. As used herein, a phrase referring to “at least one of” a list of items refers to any combination of those items, including single members. As an example, “at least one of: a, b, or c” is intended to cover a, b, c, a + b, a + c, b + c, and a + b + c, as well as any combination with multiples of the same element (e.g., a + a, a + a + a, a + a + b, a +a + c, a + b + b, a + c + c, b + b, b + b + b, b + b + c, c + c, and c + c + c, or any other ordering of a, b, and c) .

No element, act, or instruction used herein should be construed as critical or essential unless explicitly described as such. Also, as used herein, the articles “a” and “an” are intended to include one or more items and may be used interchangeably with “one or more. ” Further, as used herein, the article “the” is intended to include one or more items referenced in connection with the article “the” and may be used interchangeably with “the one or more. ” Furthermore, as used herein, the terms “set” and “group” are intended to include one or more items and may be used interchangeably with “one or more. ” Where only one item is intended, the phrase “only one” or similar language is used. Also, as used herein, the terms “has, ” “have, ” “having, ” or the like are intended to be open-ended terms that do not limit an element that they modify (e.g., an element “having” A may also have B) . Further, the phrase “based on” is intended to mean “based, at least in part, on” unless explicitly stated otherwise. Also, as used herein, the term “or” is intended to be inclusive when used in a series and may be used interchangeably with “and/or, ” unless explicitly stated otherwise (e.g., if used in combination with “either” or “only one of” ) .

Claims

An apparatus for wireless communication at a user equipment (UE) , comprising:

a memory; and

one or more processors, coupled to the memory, configured to:

receive a timing advance (TA) indication associated with a candidate serving cell configured for layer 1/layer 2 (L1/L2) mobility;

receive, after or with the TA indication, an L1 message or an L2 message instructing the UE to switch to the candidate serving cell; and

communicate with the candidate serving cell based on the L1 message or the L2 message.
The apparatus of claim 1, wherein the TA indication comprises a medium access control layer control element.
The apparatus of claim 1, wherein the L2 message comprises a medium access control layer control element.
The apparatus of claim 1, wherein the L1 message comprises downlink control information.
The apparatus of claim 1, wherein the one or more processors are further configured to:

receive a random access channel (RACH) trigger or a sounding reference signal (SRS) trigger;

transmit a RACH preamble or an SRS to the candidate serving cell based on the RACH trigger or the SRS trigger; and

receive a handover command after transmitting the RACH preamble or the SRS.
The apparatus of claim 5, wherein the TA indication is received before the handover command.
The apparatus of claim 5, wherein the TA indication is included in the handover command.
The apparatus of claim 1, wherein the TA indication includes a TA identifier associated with a TA group (TAG) that includes the candidate serving cell.
The apparatus of claim 8, wherein the TAG is associated with a transmission configuration indicator state associated with the candidate serving cell.
The apparatus of claim 8, wherein the TAG is associated with at least one reference signal associated with the candidate serving cell.
The apparatus of claim 8, wherein the TAG is a primary TAG associated with the candidate serving cell.
An apparatus for wireless communication at a network node, comprising:

a memory; and

one or more processors, coupled to the memory, configured to:

transmit a timing advance (TA) indication associated with a candidate serving cell configured for layer 1/layer 2 (L1/L2) mobility; and

transmit, after or with the TA indication, an L1 message or an L2 message instructing a user equipment (UE) to switch to the candidate serving cell.
The apparatus of claim 12, wherein the TA indication comprises a medium access control layer control element.
The apparatus of claim 12, wherein the L2 message comprises a medium access control layer control element.
The apparatus of claim 12, wherein the L1 message comprises downlink control information.
The apparatus of claim 12, wherein the one or more processors are further configured to:

transmit a random access channel (RACH) trigger or a sounding reference signal (SRS) trigger; and

transmit a handover command after transmitting the RACH trigger or the SRS trigger.
The apparatus of claim 16, wherein the TA indication is received before the handover command.
The apparatus of claim 16, wherein the TA indication is included in the handover command.
The apparatus of claim 12, wherein the TA indication includes a TA identifier associated with a TA group (TAG) that includes the candidate serving cell.
The apparatus of claim 19, wherein the TAG is associated with a transmission configuration indicator state associated with the candidate serving cell.
The apparatus of claim 19, wherein the TAG is associated with at least one reference signal associated with the candidate serving cell.
The apparatus of claim 19, wherein the TAG is a primary TAG associated with the candidate serving cell.
An apparatus for wireless communication at a user equipment (UE) , comprising:

a memory; and

one or more processors, coupled to the memory, configured to:

receive a layer 1 (L1) message or a layer 2 (L2) message instructing the UE to switch to a candidate serving cell;

receive, after the L1 message or the L2 message, a timing advance (TA) indication associated with the candidate serving cell; and

communicate with the candidate serving cell based on the TA indication.
The apparatus of claim 23, wherein the TA indication comprises a medium access control layer control element.
The apparatus of claim 23, wherein the L2 message comprises a medium access control layer control element.
The apparatus of claim 23, wherein the L1 message comprises downlink control information.
The apparatus of claim 23, wherein the TA indication includes a TA identifier associated with a TA group (TAG) that includes the candidate serving cell.
An apparatus for wireless communication at a network node, comprising:

a memory; and

one or more processors, coupled to the memory, configured to:

transmit a timing advance (TA) indication associated with a candidate serving cell configured for layer 1/layer 2 (L1/L2) mobility after an L1 message or an L2 message instructing a user equipment (UE) to switch to the candidate serving cell; and

communicate with the UE based on the TA indication.
The apparatus of claim 28, wherein the TA indication comprises a medium access control layer control element.
The apparatus of claim 28, wherein the L2 message comprises a medium access control layer control element.
The apparatus of claim 28, wherein the L1 message comprises downlink control information.
The apparatus of claim 28, wherein the TA indication includes a TA identifier associated with a TA group (TAG) that includes the candidate serving cell.