Techniques for Transport Configuration Indicator State Switching in Handover Procedures

Abstract

Methods, systems, and devices for wireless communication are described. Generally, a user equipment (UE) may communicate with a first network device in a first communication system (e.g., a non-standalone (NSA) system) before initiating a handover to a second communication system (e.g., a standalone (SA) system). In some examples, the UE may receive a first tracking reference signal (TRS) from the first network device using a first transmission configuration indicator (TCI) state. The first network device may include an indication of the first TCI state in a control message. The UE may initiate a handover from the first network device to a second network device. After the handover, the UE may receive a second TRS from the second network device. The UE may use the first TCI state to receive the second TRS based on determining that one or more antenna port configuration conditions are met.

Description

Technical Field

[0001] The following relates to wireless communication, including techniques for transmission configuration indicator state switching for handover procedures. Background Art

[0002] Wireless communication systems are widely deployed to provide various types of communication content such as voice, video, packet data, messaging, broadcasting, etc. These systems are capable of supporting communication with multiple users by sharing available system resources (e.g., time, frequency, and power). Examples of such multi-access systems include fourth-generation (4G) systems (e.g., Long Term Evolution (LTE) systems, enhanced LTE (LTE-A) systems, or LTE-A Pro systems) and fifth-generation (5G) systems (which may be referred to as New Radio (NR) systems). These systems may employ techniques such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal frequency division multiple access (OFDMA), or discrete Fourier transform spread orthogonal frequency division multiplexing (DFT-S-OFDM). A wireless multi-access communication system may include one or more base stations or one or more network access nodes, each of which simultaneously supports communication for multiple communication devices (which may alternatively be referred to as user equipment (UE)). In some examples, a UE may initiate a handover from one system or subsystem to another system or subsystem. Summary of the Invention

[0003] The described techniques relate to improved methods, systems, devices, and apparatuses for supporting techniques for transmission configuration indicator state switching for handover procedures. Generally, a user equipment (UE) may communicate with a first network device in a first communication system (e.g., a non-standalone (NSA) system) before initiating a handover to a second communication system (e.g., a standalone (SA) system). In some examples, the UE may receive a first tracking reference signal (TRS) from the first network device using a first transmission configuration indicator (TCI) state. The first network device may include an indication of the first TCI state in a control message. The UE may initiate a handover from the first network device to a second network device. After the handover, the UE may receive a second TRS from the second network device. The UE may use the first TCI state to receive the second TRS based on determining that one or more antenna port configuration conditions are met. For example, the UE may determine that an implicit lower selection has failed, there is no quasi-co-location (QCL) relationship between a synchronization signal block (SSB) and the TRS, the second network device will not send a control message indicating an updated TCI state, or any combination thereof.

[0004] Describes a method for wireless communication at a user equipment (UE). The method may include: receiving a first tracking reference signal from a first network device in a first cell using a first transmission configuration indicator state in a set of transmission configuration indicator states; initiating a handover from the first network device to a second network device; and receiving a second tracking reference signal from the second network device using the first transmission configuration indicator state, wherein using the first transmission configuration indicator state is based on meeting one or more antenna port configuration conditions.

[0005] Describes an apparatus for wireless communication at a UE. The apparatus may include a processor, a memory in electronic communication with the processor, and instructions stored in the memory. The instructions may be executable by the processor to cause the apparatus to perform the following operations: receiving a first tracking reference signal from a first network device in a first cell using a first transmission configuration indicator state in a set of transmission configuration indicator states; initiating a handover from the first network device to a second network device; and receiving a second tracking reference signal from the second network device using the first transmission configuration indicator state, wherein using the first transmission configuration indicator state is based on meeting one or more antenna port configuration conditions.

[0006] Describes another apparatus for wireless communication at a UE. The apparatus may include: a unit for receiving a first tracking reference signal from a first network device in a first cell using a first transmission configuration indicator state in a set of transmission configuration indicator states; a unit for initiating a handover from the first network device to a second network device; and a unit for receiving a second tracking reference signal from the second network device using the first transmission configuration indicator state, wherein using the first transmission configuration indicator state is based on meeting one or more antenna port configuration conditions.

[0007] Describes a non-transitory computer-readable medium storing code for wireless communication at a UE. The code may include instructions executable by a processor to perform the following operations: receiving a first tracking reference signal from a first network device in a first cell using a first transmission configuration indicator state in a set of transmission configuration indicator states; initiating a handover from the first network device to a second network device; and receiving a second tracking reference signal from the second network device using the first transmission configuration indicator state, wherein using the first transmission configuration indicator state is based on meeting one or more antenna port configuration conditions.

[0008] Some examples of the methods, apparatuses, and non-transitory computer-readable media described herein may also include operations, features, units, or instructions for performing the following: after initiating the handover, monitoring a control message including an indication of a second transmission configuration indicator state; and failing to receive the control message based on the monitoring.

[0009] Some examples of the methods, apparatuses, and non-transitory computer-readable media described herein may also include operations, features, units, or instructions for performing the following: determining that the first transmission configuration indicator state may be one of the transmission configuration indicator states in the set of transmission configuration indicator states.

[0010] Some examples of the methods, apparatuses, and non-transitory computer-readable media described herein may also include operations, features, units, or instructions for performing the following: determining that there is no quasi-co-location relationship between one or more synchronization signals and at least one of the first tracking reference signal or the second tracking reference signal.

[0011] Some examples of the methods, apparatuses, and non-transitory computer-readable media described herein may also include operations, features, units, or instructions for performing the following: using the first transmission configuration indicator state to process the second tracking reference signal; and receiving control signaling, data signaling, or both based on the processed tracking reference signal.

[0012] In some examples of the methods, apparatuses, and non-transitory computer-readable media described herein, initiating the handover may include operations, features, units, or instructions for performing the following: initiating an intra-cell handover.

[0013] In some examples of the methods, apparatuses, and non-transitory computer-readable media described herein, initiating the handover may include operations, features, units, or instructions for performing the following: initiating a handover from a non-standalone system to a standalone system.

[0014] In some examples of the methods, apparatuses, and non-transitory computer-readable media described herein, the first network device includes a base station, a repeater, a radio headend, or any combination thereof associated with a high-speed train network deployment.

[0015] Some examples of the methods, apparatuses, and non-transitory computer-readable media described herein may also include operations, features, units, or instructions for performing the following: receiving, before initiating the handover, from the first network device a control message including an indication of the first transmission configuration indicator state, wherein receiving the first tracking reference signal using the first transmission configuration indicator state may be based on receiving the control message. Description of the Drawings

[0016] Figure 1 An example of a wireless communication system supporting techniques for transmission configuration indicator state switching for a handover process in accordance with aspects of the present disclosure is shown.

[0017] Figure 2 An example of a wireless communication system supporting techniques for transmission configuration indicator state switching for a handover process in accordance with aspects of the present disclosure is shown.

[0018] Figure 3 An example of a process flow supporting techniques for transmission configuration indicator state switching for a handover process in accordance with aspects of the present disclosure is shown.

[0019] Figure 4 and 5 A block diagram of a device supporting techniques for transmission configuration indicator state switching for a handover process in accordance with aspects of the present disclosure is shown.

[0020] Figure 6 A block diagram of a communication manager supporting techniques for transmission configuration indicator state switching for a handover process in accordance with aspects of the present disclosure is shown.

[0021] Figure 7 A diagram of a system including a device supporting techniques for transmission configuration indicator state switching for a handover process in accordance with aspects of the present disclosure is shown.

[0022] Figures 8 to 11 A flowchart illustrating a method supporting techniques for transmission configuration indicator state switching for a handover process in accordance with aspects of the present disclosure is shown. DETAILED DESCRIPTION

[0023] In some cases, a wireless communication system may support various deployments and systems. For example, a user equipment (UE) in some communication systems may initiate a handover from a first communication system (e.g., a non-standalone (NSA) system such as a high-speed train (HST) deployment) to a second communication system (e.g., a standalone (SA) system). The transition from one communication system to another may introduce processing issues at the UE because the UE may rely on information specific to one communication system to handle control and data signaling in another communication system.

[0024] In some cases, a UE may rely on one or more reference signals (e.g., Tracking Reference Signal (TRS)) to establish or maintain communication with a network device. In such cases, the TRS may be quasi - co - located (QCL) with the Physical Downlink Control Channel (PDCCH), Physical Downlink Shared Channel (PDSCH), Demodulation Reference Signal (DMRS), or any combination thereof. Thus, the UE can rely on the TRS to receive and successfully process downlink information. A first network device in a first communication system may send a control message (e.g., Medium Access Control (MAC) Control Element (CE)) indicating one or more Transmission Control Information (TCI) states corresponding to the TRS for the UE to use in receiving and processing each TRS. For example, the UE may receive an indication of a first TCI state to be used for receiving and processing a first TRS, an indication of a second TCI state to be used for receiving and processing a second TRS, and so on. Thus, the UE can receive the first TRS, process the first TRS, and receive one or more of PDCCH, PDSCH, DMRS corresponding to the first TRS by identifying the correct TCI state for receiving the first TRS.

[0025] In some cases, the first communication system may support the transmission of control messages that explicitly indicate TCI states, but the second communication system may not support such signaling. Thus, when the UE initiates a handover process from the first communication system to the second communication system, the UE may expect to receive a control message indicating the TCI state for receiving subsequent TRS, but may not receive such a control message. Consequently, the UE may be unable to receive and process the TRS after the handover. This may cause the UE to be unable to process PDCCH, PDSCH, DMRS, etc. Thus, after such a handover, the UE may experience increased Block Error Rate (BLER), reduced signal throughput, and potential signal failure.

[0026] In some examples, the UE may experience a handover process from a first communication system (e.g., Non - Standalone (NSA) system, such as an HST network) to a second communication system (e.g., Standalone (SA) system). In some cases, before the handover, the UE may receive a control message (e.g., MAC CE) indicating a first TCI state. Subsequently, the UE may initiate a handover from the first communication system to the second communication system. In some cases, this handover may be referred to as an intra - cell handover. The UE may transfer the connection from a first base station (associated with the first communication system) to a second base station (associated with the second communication system).

[0027] When performing a handover, the UE can determine the TCI state for receiving subsequent TRS based on determining whether multiple antenna port configuration conditions are met. For example, the UE can determine that one or more antenna port configuration conditions are met by monitoring the MAC-CE including an indication of the TCI state and not receiving the MAC-CE. In some examples, the UE can determine that one or more antenna port configuration conditions are met by determining that multiple TCI states are configured (e.g., implicit downselection failure of TCI states). In some examples, if the UE determines that there is no QCL relationship between the synchronization signal block (SSB) and the TRS, the UE can determine that one or more antenna port configuration conditions are met. Based on determining that one or more antenna port configuration conditions are met, the UE can identify the most recent TCI state explicitly indicated prior to the handover and can use the identified TCI state to receive and process subsequent TRS after the handover. This can allow the UE to successfully process control signaling, data signaling, DMRS, etc., resulting in a continuous connection to the base station and reduced signal latency.

[0028] Aspects of the present disclosure can be implemented to achieve one or more advantages. For example, performing a handover process as described herein can result in reduced BLER, reduced likelihood of connection failure, improved communication, increased system efficiency, and improved user experience. Additionally, using the described techniques (including implementing some techniques only when one or more conditions are met) can result in efficient implementation of the described methods only when the described techniques will provide the greatest benefit to a wireless communication system.

[0029] Aspects of the present disclosure are first described in the context of a wireless communication system. Aspects of the present disclosure are further illustrated by a wireless communication system and a process flow, and aspects of the present disclosure are described with reference to the wireless communication system and the process flow. Aspects of the present disclosure are further illustrated by a device diagram, a system diagram, and a flowchart related to techniques for transmission configuration indicator state switching for a handover process, and aspects of the present disclosure are described with reference to these diagrams.

[0030] Figure 1 An example of a wireless communication system 100 supporting techniques for transmission configuration indicator state switching for a handover process in accordance with aspects of the present disclosure is shown. The wireless communication system 100 can include one or more base stations 105, one or more UEs 115, and a core network 130. In some examples, the wireless communication system 100 can be a Long-Term Evolution (LTE) network, an enhanced LTE (LTE-A) network, an LTE-A Pro network, or a New Radio (NR) network. In some examples, the wireless communication system 100 can support enhanced broadband communication, ultra-reliable communication, low-latency communication, or communication with low-cost and low-complexity devices, or any combination thereof.

[0031] Base stations 105 may be distributed throughout a geographic area to form a wireless communication system 100 and may be devices of different forms or with different capabilities. The base stations 105 and the UEs 115 may communicate wirelessly via one or more communication links 125. Each base station 105 may provide a coverage area 110, and the UEs 115 and the base stations 105 may establish one or more communication links 125 over the coverage area 110. The coverage area 110 may be an example of a geographic area over which the base stations 105 and the UEs 115 may support the transmission of signals according to one or more radio access technologies.

[0032] The UEs 115 may be distributed throughout the coverage area 110 of the wireless communication system 100, and each UE 115 may be stationary, or mobile, or both at different times. The UEs 115 may be devices of different forms or with different capabilities. Some example UEs 115 are shown in Figure 1 . The UEs 115 described herein are capable of communicating with various types of devices, such as other UEs 115, base stations 105, or network devices (e.g., core network nodes, relay devices, integrated access and backhaul (IAB) nodes, or other network devices), as Figure 1 shown.

[0033] The base stations 105 may communicate with the core network 130, or with each other, or both. For example, the base stations 105 may interface with the core network 130 via one or more backhaul links 120 (e.g., via S1, N2, N3, or other interfaces). The base stations 105 may communicate directly (e.g., directly between base stations 105) with each other, or indirectly (e.g., via the core network 130) with each other, or both, over the backhaul links 120 (e.g., via X2, Xn, or other interfaces). In some examples, the backhaul links 120 may be or include one or more wireless links.

[0034] One or more of the base stations 105 described herein may include or may be referred to by those skilled in the art as a base station transceiver, radio base station, access point, radio transceiver, Node B, evolved Node B (eNB), next generation Node B, or Gigabit Node B (either of which may be referred to as a gNB), home Node B, home evolved Node B, or some other suitable term.

[0035] The UE 115 may include or may be referred to as a mobile device, wireless device, remote device, handheld device, or subscriber device, or some other suitable term, where the "device" may also be referred to as a unit, station, terminal, or client, among other examples. The UE 115 may also include or may be referred to as a personal electronic device, such as a cellular phone, personal digital assistant (PDA), tablet computer, laptop computer, or personal computer. In some examples, the UE 115 may include or be referred to as a wireless local loop (WLL) station, Internet of Things (IoT) device, Internet of Everything (IoE) device, or machine type communication (MTC) device, among other examples, which may be implemented in various items such as appliances, or vehicles, meters, and other examples.

[0036] The UE 115 described herein is capable of communicating with various types of devices, such as other UE 115s that can sometimes act as relays, as well as base station 105 and network devices, including macro eNBs or gNBs, small cell eNBs or gNBs, or relay base stations, among other examples, as Figure 1 shown.

[0037] The UE 115 and the base station 105 may wirelessly communicate with each other over one or more carriers via one or more communication links 125. The term "carrier" may refer to a collection of radio frequency spectrum resources having a defined physical layer structure for supporting the communication link 125. For example, a carrier for the communication link 125 may include a portion of a radio frequency spectrum band (e.g., a bandwidth part (BWP)) that operates in accordance with one or more physical layer channels for a given radio access technology (e.g., LTE, LTE-A, LTE-A Pro, NR). Each physical layer channel may carry acquisition signaling (e.g., synchronization signals, system information), control signaling for coordinating the operation of the carrier, user data, or other signaling. The wireless communication system 100 may support communication with the UE 115 using carrier aggregation or multi-carrier operation. According to a carrier aggregation configuration, the UE 115 may be configured with multiple downlink component carriers and one or more uplink component carriers. Carrier aggregation may be used with both frequency division duplex (FDD) component carriers and time division duplex (TDD) component carriers.

[0038] In some examples (e.g., in a carrier aggregation configuration), a carrier may also have acquisition signaling or control signaling that coordinates operations for other carriers. A carrier may be associated with a frequency channel (e.g., an evolved universal mobile telecommunications system terrestrial radio access (E-UTRA) absolute radio frequency channel number (EARFCN)) and may be placed according to a channel raster for discovery by the UE 115. A carrier may operate in an independent mode where the UE 115 performs initial acquisition and connection via the carrier, or a carrier may operate in a non-independent mode where a different carrier (e.g., of the same or a different radio access technology) is used to anchor the connection.

[0039] The communication link 125 shown in the wireless communication system 100 may include an uplink transmission from the UE 115 to the base station 105 or a downlink transmission from the base station 105 to the UE 115. A carrier may carry downlink or uplink communication (e.g., in an FDD mode) or may be configured to carry both downlink and uplink communication (e.g., in a TDD mode).

[0040] A carrier may be associated with a bandwidth of the radio frequency spectrum, and in some examples, the carrier bandwidth may be referred to as the "system bandwidth" of the carrier or the wireless communication system 100. For example, the carrier bandwidth may be one of a number of defined bandwidths for carriers of a radio access technology (e.g., 1.4, 3, 5, 10, 15, 20, 40, or 80 megahertz (MHz)). Devices of the wireless communication system 100 (e.g., the base station 105, the UE 115, or both) may have a hardware configuration that supports communication over the carrier bandwidth or may be configurable to support communication over one of a set of carrier bandwidths. In some examples, the wireless communication system 100 may include a base station 105 or a UE 115 that supports simultaneous communication via carriers associated with multiple carrier bandwidths. In some examples, each served UE 115 may be configured to operate over a portion (e.g., a sub-band, a BWP) or all of the carrier bandwidth.

[0041] The signal waveform transmitted on a carrier can be composed of multiple subcarriers (e.g., using a multi-carrier modulation (MCM) technique such as orthogonal frequency division multiplexing (OFDM) or discrete Fourier transform spread spectrum OFDM (DFT-S-OFDM)). In a system employing an MCM technique, a resource element can include a symbol period (e.g., the duration of a modulated symbol) and a subcarrier, where the symbol period and the subcarrier spacing are inversely related. The number of bits carried by each resource element can depend on the modulation scheme (e.g., the order of the modulation scheme, the coding rate of the modulation scheme, or both). Thus, the more resource elements received by the UE 115 and the higher the order of the modulation scheme, the higher the data rate can be for the UE 115. Wireless communication resources can refer to a combination of radio frequency spectrum resources, time resources, and spatial resources (e.g., spatial layers or beams), and the use of multiple spatial layers can further increase the data rate or data integrity for communication with the UE 115.

[0042] One or more numerologies for a carrier can be supported, where a numerology can include a subcarrier spacing (Δf) and a cyclic prefix. A carrier can be divided into one or more BWPs with the same or different numerologies. In some examples, the UE 115 can be configured with multiple BWPs. In some examples, a single BWP for a carrier can be active at a given time, and communication for the UE 115 can be restricted to one or more active BWPs.

[0043] Time intervals for the base station 105 or the UE 115 can be represented as multiples of a basic time unit, which can refer to, for example, a sampling period of T s = 1 / (Δf max ·N f ) seconds, where Δf max can represent the maximum supported subcarrier spacing, and N f can represent the maximum supported discrete Fourier transform (DFT) size). The time intervals of communication resources can be organized according to radio frames, each having a specified duration (e.g., 10 milliseconds (ms)). Each radio frame can be identified by a system frame number (SFN) (e.g., ranging from 0 to 1023).

[0044] Each frame may include a plurality of consecutively numbered sub - frames or time slots, and each sub - frame or time slot may have the same duration. In some examples, a frame may be divided (e.g., in the time domain) into sub - frames, and each sub - frame may be further divided into a number of time slots. Alternatively, each frame may include a variable number of time slots, and the number of time slots may depend on the sub - carrier spacing. Each time slot may include a number of symbol periods (e.g., depending on the length of the cyclic prefix added in front of each symbol period). In some wireless communication systems 100, a time slot may be further divided into a plurality of mini - slots each containing one or more symbols. Excluding the cyclic prefix, each symbol period may contain one or more (e.g., N f f

[0045] sub - frames, time slots, mini - slots, or symbols may be the smallest scheduling unit (e.g., in the time domain) of the wireless communication system 100 and may be referred to as a transmission time interval (TTI). In some examples, the TTI duration (e.g., the number of symbol periods in a TTI) may be variable. Additionally or alternatively, the smallest scheduling unit of the wireless communication system 100 may be dynamically selected (e.g., in the form of a burst of shortened TTIs (sTTIs)).

[0046] Physical channels may be multiplexed on a carrier according to various techniques. For example, time - division multiplexing (TDM) techniques, frequency - division multiplexing (FDM) techniques, or one or more of hybrid TDM - FDM techniques may be used to multiplex physical control channels and physical data channels on a downlink carrier. The control region for a physical control channel (e.g., a control resource set (CORESET)) may be defined by the number of symbol periods and may extend across the system bandwidth of the carrier or a subset of the system bandwidth. One or more control regions (e.g., CORESETs) may be configured for a group of UEs 115. For example, one or more of the UEs 115 may monitor or search for control regions for control information according to one or more search space sets, and each search space set may include one or more control channel candidates at one or more aggregation levels arranged in a cascaded manner. The aggregation level for a control channel candidate may refer to the number of control channel resources (e.g., control channel elements (CCEs)) associated with the coded information for a control information format having a given payload size. The search space set may include a common search space set configured to send control information to multiple UEs 115 and a UE - specific search space set for sending control information to a particular UE 115.

[0047] Each base station 105 can provide communication coverage via one or more cells (e.g., macro cells, small cells, hotspots, or other types of cells, or any combination thereof). The term "cell" can refer to a logical communication entity for communicating with base station 105 (e.g., on a carrier), and can be associated with an identifier for differentiating adjacent cells (e.g., physical cell identifier (PCID), virtual cell identifier (VCID), or other identifier). In some examples, a cell can also refer to a geographic coverage area 110 or a portion of the geographic coverage area 110 (e.g., a sector) on which the logical communication entity operates. Depending on various factors (such as the capabilities of base station 105), the range of such a cell can range from a relatively small area (e.g., a structure, a subset of a structure) to a relatively large area. For example, a cell can be or include a building, a subset of a building, or an external space between or overlapping with geographic coverage areas 110, among other examples.

[0048] Macro cells typically cover a relatively large geographic area (e.g., with a radius of several kilometers) and can allow unrestricted access by UEs 115 having a service subscription with the network provider that supports the macro cell. Compared to macro cells, small cells can be associated with lower-power base stations 105, and small cells can operate in the same or different (e.g., licensed, unlicensed) frequency bands as macro cells. Small cells can provide unrestricted access to UEs 115 having a service subscription with the network provider, or can provide restricted access to UEs 115 associated with the small cell (e.g., UEs 115 in a closed subscriber group (CSG), UEs 115 associated with users in a residence or office). Base station 105 can support one or more cells and can also support communicating on one or more cells using one or more component carriers.

[0049] In some examples, a carrier can support multiple cells and can be configured with different cell types according to different protocol types that can provide access for different types of devices (e.g., MTC, narrowband IoT (NB-IoT), enhanced mobile broadband (eMBB)).

[0050] In some examples, base station 105 can be movable, and thus, provide communication coverage for a moving geographic coverage area 110. In some examples, different geographic coverage areas 110 associated with different technologies can overlap, but different geographic coverage areas 110 can be supported by the same base station 105. In other examples, overlapping geographic coverage areas 110 associated with different technologies can be supported by different base stations 105. The wireless communication system 100 can include, for example, a heterogeneous network, where different types of base stations 105 use the same or different radio access technologies to provide coverage for respective geographic coverage areas 110.

[0051] The wireless communication system 100 can support synchronous or asynchronous operation. For synchronous operation, base stations 105 can have similar frame timings, and transmissions from different base stations 105 can be approximately aligned in time. For asynchronous operation, base stations 105 can have different frame timings, and in some examples, transmissions from different base stations 105 can not be aligned in time. The techniques described herein can be used for synchronous or asynchronous operation.

[0052] Some UEs 115 (e.g., MTC or IoT devices) can be low-cost or low-complexity devices, and can provide automated communication between machines (e.g., via machine-to-machine (M2M) communication). M2M communication or MTC can refer to data communication technologies that allow devices to communicate with each other or with a base station 105 without human intervention. In some examples, M2M communication or MTC can include communication from devices integrated with sensors or meters to measure or capture information and relay such information to a central server or application that utilizes the information or presents the information to a human who interacts with the application. Some UEs 115 can be designed to collect information or implement automated behavior of machines or other devices. Examples of applications for MTC devices include smart metering, inventory monitoring, water level monitoring, device monitoring, healthcare monitoring, wildlife monitoring, climate and geological event monitoring, fleet management and tracking, remote security sensing, physical access control, and transaction-based business billing.

[0053] Some UEs 115 may be configured to operate in a power-reduced mode of operation, e.g., half-duplex communication (e.g., a mode that supports one-way communication via transmission or reception rather than simultaneous transmission and reception). In some examples, half-duplex communication may be performed at a reduced peak rate. Other power saving techniques for UEs 115 include entering a power-saving deep sleep mode when not participating in active communication, when operating on a limited bandwidth (e.g., in accordance with narrowband communication), or a combination of these techniques. For example, some UEs 115 may be configured for operation using a narrowband protocol type associated with a defined portion or extent (e.g., a set of subcarriers or resource blocks (RBs)) within a carrier, within a guard band of a carrier, or external to a carrier.

[0054] The wireless communication system 100 may be configured to support ultra-reliable communication or low-latency communication, or various combinations thereof. For example, the wireless communication system 100 may be configured to support ultra-reliable low-latency communication (URLLC) or mission-critical communication. The UE 115 may be designed to support ultra-reliability, low latency, or critical functions (e.g., mission-critical functions). Ultra-reliable communication may include private communication or group communication and may be supported by one or more mission-critical services such as mission-critical push-to-talk (MCPTT), mission-critical video (MCVideo), or mission-critical data (MCData). Support for mission-critical functions may include prioritization of services, and mission-critical services may be used for public safety or general commercial applications. The terms ultra-reliable, low-latency, mission-critical, and ultra-reliable low-latency may be used interchangeably herein.

[0055] In some examples, the UE 115 is capable of communicating directly with other UEs 115 over a device-to-device (D2D) communication link 135 (e.g., using a peer-to-peer (P2P) or D2D protocol). One or more UEs 115 utilizing D2D communication may be within the geographic coverage area 110 of the base station 105. Other UEs 115 in such a group may be outside the geographic coverage area 110 of the base station 105 or otherwise unable to receive transmissions from the base station 105. In some examples, groups of UEs 115 communicating via D2D communication may utilize a one-to-many (1:M) system where each UE 115 transmits to each other UE 115 in the group. In some examples, the base station 105 facilitates scheduling of resources for D2D communication. In other cases, D2D communication is performed between UEs 115 without involving the base station 105.

[0056] In some systems, the D2D communication link 135 can be an example of a communication channel (such as a sidelink communication channel) between vehicles (e.g., UE 115). In some examples, vehicles can communicate using vehicle-to-everything (V2X) communication, vehicle-to-vehicle (V2V) communication, or some combination of these. Vehicles can signal information related to traffic conditions, signal scheduling, weather, safety, emergencies, or any other information related to the V2X system. In some examples, vehicles in a V2X system can communicate with roadside infrastructure (such as a roadside unit), or communicate with the network via one or more network nodes (e.g., base station 105) using vehicle-to-network (V2N) communication, or perform both operations.

[0057] The core network 130 can provide user authentication, access authorization, tracking, Internet Protocol (IP) connectivity, and other access, routing, or mobility functions. The core network 130 can be an evolved packet core (EPC) or a 5G core (5GC), which can include at least one control plane entity that manages access and mobility (e.g., a mobility management entity (MME), an access and mobility management function (AMF)) and at least one user plane entity that routes packets to or interconnects with an external network (e.g., a serving gateway (S-GW), a packet data network (PDN) gateway (P-GW), or a user plane function (UPF)). The control plane entity can manage non-access stratum (NAS) functions, such as mobility, authentication, and bearer management for the UE 115 served by the base station 105 associated with the core network 130. User IP packets can be transmitted through the user plane entity, which can provide IP address allocation and other functions. The user plane entity can be connected to IP services 150 for one or more network operators. The IP services 150 can include access to the Internet, an intranet, an IP multimedia subsystem (IMS), or packet-switched streaming services.

[0058] Some network devices in the network device (e.g., base station 105) can include subcomponents such as an access network entity 140, which can be an example of an access node controller (ANC). Each access network entity 140 can communicate with the UE 115 through one or more other access network transmission entities 145 (which can be referred to as radio heads, intelligent radio heads, or transmit / receive points (TRPs)). Each access network transmission entity 145 can include one or more antenna panels. In some configurations, the various functions of each access network entity 140 or base station 105 can be distributed across various network devices (e.g., radio heads and ANCs) or combined into a single network device (e.g., base station 105).

[0059] The wireless communication system 100 can operate using one or more frequency bands, typically in the range of 300 megahertz (MHz) to 300 gigahertz (GHz). Generally, the region from 300 MHz to 3 GHz is referred to as the ultra-high frequency (UHF) region or the decimeter band because the wavelength range is approximately from one decimeter to one meter in length. UHF waves may be blocked or redirected by buildings and environmental features, but the waves can be sufficient to penetrate structures to serve UEs 115 located indoors from a macro cell. Compared to transmissions using smaller frequencies and longer waves in the high frequency (HF) or very high frequency (VHF) portions of the spectrum below 300 MHz, UHF wave transmissions can be associated with smaller antennas and shorter distances (e.g., less than 100 kilometers).

[0060] The wireless communication system 100 can also operate in the super-high frequency (SHF) region using frequency bands from 3 GHz to 30 GHz (also referred to as the centimeter band) or in the extremely high frequency (EHF) region of the spectrum (e.g., from 30 GHz to 300 GHz) (also referred to as the millimeter band). In some examples, the wireless communication system 100 can support millimeter wave (mmW) communication between the UE 115 and the base station 105, and the EHF antennas of the corresponding devices can be even smaller and more closely spaced compared to UHF antennas. In some examples, this can facilitate the use of antenna arrays within the device. However, compared to SHF or UHF transmissions, EHF transmissions may suffer even greater atmospheric attenuation and shorter distances. The techniques disclosed herein can be employed across transmissions using one or more different frequency regions, and the designation of the use of frequency bands across these frequency regions can vary according to the country or regulatory body.

[0061] The wireless communication system 100 can utilize both licensed and unlicensed radio frequency spectrum bands. For example, the wireless communication system 100 can employ licensed-assisted access (LAA), LTE-unlicensed (LTE-U) radio access technology, or NR technology in an unlicensed frequency band such as the 5 GHz industrial, scientific, and medical (ISM) band. When operating in an unlicensed radio frequency spectrum band, devices such as the base station 105 and the UE 115 can employ carrier sensing for collision detection and avoidance. In some examples, operation in an unlicensed frequency band can be based on a carrier aggregation configuration that combines a component carrier operating in a licensed frequency band (e.g., LAA). Operation in the unlicensed spectrum can include downlink transmissions, uplink transmissions, peer-to-peer (P2P) transmissions, or device-to-device (D2D) transmissions, among other examples.

[0062] Base station 105 or UE 115 may be equipped with multiple antennas, which may be used to employ techniques such as transmit diversity, receive diversity, multiple-input multiple-output (MIMO) communication, or beamforming. The antennas of base station 105 or UE 115 may be located within one or more antenna arrays or antenna panels (which may support MIMO operation or transmit or receive beamforming). For example, one or more base station antennas or antenna arrays may be co-located at an antenna assembly, such as an antenna tower. In some examples, the antennas or antenna arrays associated with base station 105 may be located at different geographical locations. Base station 105 may have an antenna array having a number of rows and columns of antenna ports that base station 105 may use to support beamforming for communication with UE 115. Similarly, UE 115 may have one or more antenna arrays that may support various MIMO or beamforming operations. Additionally or alternatively, an antenna panel may support radio frequency beamforming for signals transmitted via an antenna port.

[0063] Base station 105 or UE 115 may use MIMO communication to exploit multipath signal propagation and improve spectral efficiency by transmitting or receiving multiple signals via different spatial layers. Such techniques may be referred to as spatial multiplexing. For example, a transmitting device may transmit multiple signals via different antennas or different combinations of antennas. Similarly, a receiving device may receive multiple signals via different antennas or different combinations of antennas. Each of the multiple signals may be referred to as a separate spatial stream and may carry bits associated with the same data stream (e.g., the same codeword) or different data streams (e.g., different codewords). Different spatial layers may be associated with different antenna ports for channel measurement and reporting. MIMO techniques include single-user MIMO (SU-MIMO) (where multiple spatial layers are transmitted to the same receiving device) and multi-user MIMO (MU-MIMO) (where multiple spatial layers are transmitted to multiple devices).

[0064] Beamforming (which may also be referred to as spatial filtering, directional transmission, or directional reception) is a signal processing technique that can be used at a transmitting device or a receiving device (e.g., base station 105, UE 115) to form or direct an antenna beam (e.g., transmit beam, receive beam) along a spatial path between the transmitting device and the receiving device. Beamforming can be achieved by combining signals transmitted via the antenna elements of an antenna array such that some signals propagating in a particular orientation relative to the antenna array experience constructive interference while other signals experience destructive interference. The adjustment of the signals transmitted via the antenna elements can include the transmitting device or the receiving device applying an amplitude offset, a phase offset, or both to the signals carried via the antenna elements associated with the device. The adjustment associated with each antenna element in the antenna elements can be defined by a set of beamforming weights associated with a particular orientation (e.g., relative to the antenna array of the transmitting device or the receiving device, or relative to some other orientation).

[0065] As part of the beamforming operation, the base station 105 or the UE 115 can use beam scanning techniques. For example, the base station 105 can use multiple antennas or antenna arrays (e.g., antenna panels) to perform beamforming operations for directional communication with the UE 115. The base station 105 can transmit some signals (e.g., synchronization signals, reference signals, beam selection signals, or other control signals) multiple times in different directions. For example, the base station 105 can transmit signals according to different sets of beamforming weights associated with different transmission directions. Transmissions in different beam directions can be used (e.g., by the transmitting device such as the base station 105 or by the receiving device such as the UE 115) to identify the beam direction for subsequent transmissions or receptions performed by the base station 105.

[0066] The base station 105 can transmit some signals (e.g., data signals associated with the receiving device) in a single beam direction (e.g., the direction associated with a particular receiving device (e.g., UE 115)). In some examples, the beam direction associated with the transmission along a single beam direction can be determined based on the signals transmitted in one or more beam directions. For example, the UE 115 can receive one or more of the signals transmitted by the base station 105 in different directions and can report to the base station 105 an indication of the signal that has the highest signal quality or otherwise acceptable signal quality received by the UE 115.

[0067] In some examples, multiple beam directions can be used to perform transmissions by a device (e.g., by base station 105 or UE 115), and the device can use a combination of digital precoding or radio frequency beamforming to generate a combined beam for transmission (e.g., from base station 105 to UE 115). UE 115 can report feedback indicating precoding weights for one or more beam directions, and the feedback can correspond to a configured number of beams across the system bandwidth or one or more subbands. Base station 105 can transmit reference signals (e.g., cell-specific reference signal (CRS), channel state information reference signal (CSI-RS)) that can be precoded or not precoded. UE 115 can provide feedback for beam selection, which can be a precoding matrix indicator (PMI) or codebook-based feedback (e.g., multi-panel type codebook, linear combination type codebook, port selection type codebook). Although these techniques are described with reference to signals transmitted by base station 105 in one or more directions, UE 115 can employ similar techniques to transmit signals multiple times in different directions (e.g., for identifying beam directions for subsequent transmissions or receptions by UE 115) or to transmit signals in a single direction (e.g., for transmitting data to a receiving device).

[0068] When receiving various signals (such as synchronization signals, reference signals, beam selection signals, or other control signals) from base station 105, a receiving device (e.g., UE 115) can attempt multiple receiving configurations (e.g., directional listening). For example, the receiving device can receive by receiving via different antenna subarrays, by processing received signals according to different antenna subarrays, by receiving according to different sets of receive beamforming weights applied to signals received at multiple antenna elements of an antenna array (e.g., different sets of directional listening weights), or by processing received signals according to different sets of receive beamforming weights applied to signals received at multiple antenna elements of an antenna array (any of the above operations can be referred to as "listening" according to different receiving configurations or receiving directions), thereby attempting multiple receiving directions. In some examples, the receiving device can use a single receiving configuration to receive along a single beam direction (e.g., when receiving a data signal). The single receiving configuration can be aligned in a beam direction determined based on listening according to different receiving configuration directions (e.g., a beam direction determined to have the highest signal strength, the highest signal-to-noise ratio (SNR), or otherwise acceptable signal quality based on listening according to multiple beam directions).

[0069] The wireless communication system 100 can be a packet-based network that operates according to a layered protocol stack. In the user plane, communication at the bearer or packet data convergence protocol (PDCP) layer can be IP-based. The radio link control (RLC) layer can perform packet segmentation and reassembly for transmission over logical channels. The media access control (MAC) layer can perform priority handling and multiplexing of logical channels to transport channels. The MAC layer can also use error detection techniques, error correction techniques, or both to support retransmission at the MAC layer to improve link efficiency. In the control plane, the radio resource control (RRC) protocol layer can provide the establishment, configuration, and maintenance of an RRC connection (which supports radio bearers for user plane data) between the UE 115 and the base station 105 or the core network 130. At the physical layer, transport channels can be mapped to physical channels.

[0070] The UE 115 and the base station 105 can support retransmission of data to increase the likelihood that the data is successfully received. Hybrid automatic repeat request (HARQ) feedback is a technique for increasing the likelihood that data is correctly received over the communication link 125. HARQ can include a combination of error detection (e.g., using cyclic redundancy check (CRC)), forward error correction (FEC), and retransmission (e.g., automatic repeat request (ARQ)). HARQ can improve throughput at the MAC layer in poor radio conditions (e.g., low signal-to-noise conditions). In some examples, the device can support same-slot HARQ feedback, where the device can provide HARQ feedback for data received in previous symbols in a particular slot in that slot. In other cases, the device can provide HARQ feedback in a subsequent slot or according to some other time interval.

[0071] Generally, the UE 115 can communicate with a first network device (e.g., the base station 105) in a first communication system (e.g., a non-standalone (NSA) system) before initiating a handover to a second communication system (e.g., a standalone (SA) system). In some examples, the UE 115 can receive a first tracking reference signal (TRS) from the first network device using a first TCI state. The first network device can include an indication of the first TCI state in a control message. The UE 115 can initiate a handover from the first network device to a second network device. After the handover, the UE 115 can receive a second TRS from the second network device. The UE 115 can receive the second TRS using the first TCI state based on determining that one or more antenna port configuration conditions are met.

[0072] Figure 2FIG. 0 shows an example of a wireless communication system 200 that supports techniques for switching a transmission configuration indicator state for a handover procedure in accordance with various aspects of the present disclosure. In some examples, the wireless communication system 200 may include a UE 215, a base station 205, a network device 220, etc., which may be examples of corresponding devices described with reference to Figure 1 For example, the network device 220 may be a base station 105, an access network transport entity 145, a repeater, a transmit receive point (TRP), a remote radio head (RRH), an access point (AP), or any combination thereof. Each network device 220 may be managed, controlled, or otherwise signaled by another network device (e.g., a controller or a base station).

[0073] In some examples, the wireless communication system 200 may support multiple communication systems or subsystems. For example, the wireless communication system 200 may support a first communication system (e.g., an NSA system) and a second communication system (e.g., an SA system). In some examples, the first communication system may include a deployment of HSTs 210 for HSTs. The first communication system may include one or more network devices 220. For example, the network device 220 may be a repeater deployed along the track of the HST 210. The network device 220 may generate or forward signaling for UEs 215 on the HST 210 (e.g., UEs 215 carried by passengers, UEs attached to or co-located with the HST 210, etc.).

[0074] In some examples, the first communication system may support the transmission of one or two synchronization signal blocks (SSBs). For example, each network device 220 may transmit the same one or two SSBs (e.g., SSB 0 and SSB 1) using a wide beam or a coarse beam. Each cell of the first communication system may support multiple network devices (e.g., six network devices 220, including network device 220-a, network device 220-b, network device 220-c, and network device 220-d). In some examples, each network device 220 may transmit one or more reference signals according to different TCI states. For example, each network device 220 may transmit a TRS 225 according to different TCI states. In such an example, network device 220-a may transmit a TRS 225-a according to a first TCI state, network device 220-b may transmit a TRS 225-b according to a second TCI state, network device 220-c may transmit a TRS 225-c according to a third TCI state, and network device 220-d may transmit a TRS 225-d according to a fourth TCI state.

[0075] The UE 215 may rely on the TRS for subsequent reception and decoding of control or data channels. In some examples, the TRS 225 may not have a QCL relationship with the common or repeated SSB transmitted by all network devices 220 in a cell of the first communication system. However, the TRS may have a QCL relationship with the physical downlink control channel (PDCCH), the physical downlink shared channel (PDSCH), etc. Thus, by identifying and receiving the TRS, the UE 215 can successfully and efficiently receive and decode the control signaling on the PDCCH, the data signaling on the PDSCH, or both.

[0076] Since each network device 220 transmits a separate TRS according to different TCI states, the UE 215 can update its TCI state as it travels along the orbit of the HST 210. That is, when the UE 215 travels along the orbit of the HST 210, the communication quality with, for example, network device 220-a may degrade, and the UE 215 may alternatively communicate with network device 220-b. If the UE 215 updates its TCI state for receiving signaling (e.g., TRS 225-b) from network device 220-b, the communication can be switched from network device 220-a to network device 220-b. When the UE 215 travels along the HST orbit, the network can update its TCI state. The network device 220 can determine the correct TCI state for transmitting the TRS based on the uplink signal (e.g., sounding reference signal (SRS)) received from the UE 215. In some examples, the network device 220 may not rely on the SSB index report to update the TCI state. The network device 220 can send a control message (e.g., MAC-CE) with an explicit indication of the updated or activated TCI state. Thus, the network device 220 can explicitly signal the TCI state to the UE 215 and can expect the UE 215 to update its TCI state for receiving one or more subsequent TRS 225. Thus, the network (e.g., via one or more network devices 220) can indicate to the UE 215 that it should use a first TCI state to receive TRS 225-a, a second TCI state to receive TRS 225-b, a third TCI state to receive TRS 225-c, and a fourth TCI state to receive TRS 225-d.

[0077] After receiving an indication of which TCI states to use from the network (e.g., via one or more MAC-CEs), the UE 215 may successfully receive one or more TRSs 225. Based on the QCL relationship with the PDSCH or PDCCH, and based on the information received in the TRS (e.g., timing information, resource information, location information, tracking information, or any combination thereof), the UE 215 may receive control signaling, data signaling, or both from the network (e.g., via one or more network devices 220).

[0078] The UE 215 can be switched from a first communication system (e.g., HST deployment) to a second communication system (e.g., NSA 5G system). For example, the user carrying the UE 215 may get off the HST 210, or the HST 210 may stop, or the service for HST deployment may degrade, etc. The UE 215 can initiate a handover from the first communication system (e.g., from the first network device 220) to the second communication system (e.g., to the base station 205 serving the UE 215 within the coverage area 110-a). Such a handover can be considered (e.g., by the network) as an intra-cell handover. In such an example, the UE 215 can establish a two-way communication link 230 with the base station 205 (e.g., and can stop communicating with one or more network devices 220 of the first communication system or stop monitoring the communication from one or more network devices 220 of the first communication system). In some examples, after such a transition, the UE 215 may experience a higher block error (BLER) rate. For example, when switching from an NSA system (e.g., HST deployment) to an SA system, the UE 215 may fail to successfully receive or process the TRS sent by the base station 205. The network can consider such a handover as an intra-cell handover. However, in some examples, the second communication system (e.g., SA system) may not support explicit TCI state indication via control signaling (e.g., MAC-CE). For example, the UE 215 can monitor updated TCI state indication from the base station 205 (e.g., via MAC-CE). However, the base station 205 may not support such signaling (e.g., may not send such a MAC-CE, or may not include the TCI state indication in such a MAC-CE). In such an example, the UE 215 may fail to determine which TCI state to use to monitor and receive the TRS from the base station 205. As a result, the UE 215 may fail to receive one or more subsequent TRSs from the base station 205 and may fail to receive the corresponding or subsequent data signal or control signal or both. If the UE 215 is only configured with a single TCI state or a single active TCI state, the UE 215 can simply perform an implicit downselection (e.g., using a single TCI state) to receive subsequent TRSs from the base station 205. However, if the UE 215 is configured with multiple TCI states or multiple active TCI states, the UE 215 may not be able to implicitly downselect a single TCI state.

[0079] Thus, if the UE 215 transitions from a first communication system (e.g., HST deployment) to a second communication system (e.g., 5G system or SA system), the UE 215 may rely on or expect to receive a MAC-CE indicating the TCI state for receiving subsequent TRSs. If the base station 205 does not support the transmission of such a MAC-CE, the UE 215 may not be able to determine which of the multiple TCI states to use for receiving and processing subsequent TRSs from the base station 205. In such an example, the UE 215 may fail to receive one or more TRSs sent by the base station 205, which may result in partial or complete failure in processing subsequent control signaling, data signaling, or both.

[0080] The UE 215 may configure the TCI state based on determining whether one or more antenna port configuration conditions are met after initiating a handover. If such a condition is met, the UE 215 may receive the TRS using the previously used (e.g., most recently used prior to the handover) TCI state after initiating the handover. For example, the UE 215 may determine that a handover (e.g., same cell handover) has occurred or is occurring. In such an example, the UE 215 may determine whether a first condition is met. For example, the UE 215 may determine whether a QCL relationship exists or is configured between the SSB and the TRS. If no QCL relationship exists between the SSB and the TRS (e.g., the UE 215 is operating in or has been in a first communication system or is transitioning to a second communication system), the UE 215 may consider the first condition to be met. The UE 215 may determine whether a second condition is met. For example, the UE 215 may determine whether implicit downselection is available or whether implicit downselection has failed. If implicit downselection has failed or is unavailable (e.g., if the UE 215 is configured with multiple TCI states and thus cannot simply continue to use a single configured TCI state), the UE 215 may consider the second condition to be met. The UE 215 may determine whether it will receive a TCI state indication in a control message (e.g., MAC-CE) after initiating the handover. For example, the UE 215 may monitor, via the two-way communication link 230, a MAC-CE from the base station 205 carrying an explicit indication of the updated TCI state after initiating the handover. If the UE 215 does not receive such a MAC-CE, or if the UE 215 receives a MAC-CE but determines that the received MAC-CE does not include such an indication of the updated TCI state, the UE 215 may consider the third condition to be met. In some examples, if all three conditions are met, the UE 215 may continue to use the previously used TCI state to receive the TRS. In some examples, if one or more of the conditions or other conditions are met, the UE 215 may continue to use the previously used TCI state. If all three conditions are met, the UE 215 may proceed as described herein.

[0081] If the UE 215 determines that the conditions are met, the UE 215 may select a previously used TCI state to receive subsequent TRSs. For example, the UE 215 may be configured with multiple TCI states (e.g., six TCI states for a cell in a first communication system). The UE 215 may travel along the track for the HST 210 and may use the first TCI state to receive the TRS 225-a, then use the second TCI state to receive the TRS 225-b, and then use the third TCI state to receive the TRS 225-c. However, before using the fourth TCI state to receive the TRS 225-d, the UE 215 may initiate a handover to the base station 205. If the UE 215 determines that one or more of the conditions are met (e.g., all conditions are met), the UE 215 may use the most recently used TCI state (e.g., the third TCI state) before the handover to receive the next TRS from the base station 205. The UE 215 may then successfully receive and process downlink control signaling, downlink data signaling, or both (e.g., using the third TCI state or based on the received TRS, or both).

[0082] The techniques described herein may improve UE performance after a handover. However, such techniques may only be deployed if all conditions are met, which may result in the efficient deployment of the described techniques when useful (e.g., for NSA to SA handover), and the inefficient deployment of the described method in all cases. For example, if the handover is accompanied by a TCI indication from the MAC-CE, the UE may not use the described techniques because the handover does not result in a service degradation with increased BLER. However, in such an example, at least one condition will not be met, and the UE 215 may avoid implementing the described techniques.

[0083] The techniques described herein may improve UE performance after a handover. Such a handover may be used for a handover from an NSA system to an SA system, a handover from an SA system to an NSA system, an HST deployment to a legacy 4G system or a 5G system, an intra-cell handover, or any other handover performed by the UE. The UE 215 may determine whether the conditions are met and may select a TCI state based on whether the conditions are met after such a handover, as described in more detail with reference to Figure 3 more specifically described.

[0084] Figure 3 An example of a process flow 300 is shown that supports techniques for transmission configuration indicator state switching for a handover procedure in accordance with various aspects of the present disclosure. The process flow 300 may include one or more UEs 315, which may be respectively referred to Figure 1 and 2An example of the described UE 115 or UE 215. The process flow 300 may include one or more wireless network devices (e.g., base station 305), which may be examples of base station 105, base station 205, network device 220, etc. as described with reference to Figure 1 and 2 the described base station 105, base station 205, network device 220, etc.

[0085] In some examples, base station 305 may correspond to different communication systems. For example, base station 305-a may correspond to a first wireless system (e.g., a network device in an NSA deployment, such as a repeater, RRH, TRP, etc.), while base station 305-b may correspond to a second communication system (e.g., base station 105 in an SA 4G or 5G deployment). Additionally or alternatively, base station 305-a or base station 305-b or both may be examples of a base station, IAB node, repeater node (e.g., configured with some retransmission capabilities), etc. In some examples, an NSA system may use a 4G core network to deploy 5G communications, where an SA system may use only 5G core network and devices for 5G deployment. Formatted control information, reference signals, data transmissions, etc. may vary depending on the communication system. For example, base station 305-b operating in an NSA system may indicate control information at a first location within a control message, while an SA system may indicate the same control information in a different control message, or may not indicate the same control information at all. Similarly, base station 305-a may format output control information and reference signals based on formatting specific to the first communication system. In some examples, base station 305-a and base station 305-b may be separate entities located in different physical spaces. However, in some examples, base station 305-a and base station 305-b may be co-located, or may be the same network entity that operates in the role of a first base station (e.g., as part of a first communication system) and subsequently operates in the role of a second base station (e.g., part of a second communication system).

[0086] At 320, base station 305-a may send a control message to UE 315. In some cases, the control message may be a MAC-CE, which may include an explicit indication of one or more TCI states. UE 315 may receive the control message indicating one or more TCI states. UE 315 may use the TCI state to identify and process one or more subsequent TRSs. If base station 305-a does not send a control message to UE 315, the UE may not be able to process the TRS, potentially resulting in increased BLER, disconnection of the connection between UE 315 and base station 305-a, etc.

[0087] At 325, after receiving, at 320, a control message indicating one or more first TCI states, the UE 315 may identify the first TCI state as indicated in the control message. The UE 315 may be configured with multiple TCI states. When identifying the first TCI state among the multiple TCI states, the UE 315 may configure itself according to the first TCI state. For example, the UE 315 may configure one or more antennas and one or more antenna ports according to the first TCI state. Configuring the UE 315 according to the first TCI state may allow the UE to process subsequent TRSs transmitted by the base station 305-a or another base station in the first communication system according to the first TCI.

[0088] At 330, the base station 305-a (or another base station 305 of the first communication system) may transmit a first TRS. The UE 315 may use the indicated first TCI state to receive the first TRS (e.g., based on the indication of the first TCI state according to the configuration of antennas and antenna ports). The UE 315 may use the received TRS for time and frequency tracking of subsequent control signaling, data signaling, or a combination thereof.

[0089] At 335, the UE 315 may process the received first TRS based on the first TCI state. The UE 315 may determine that the first TRS is QCL with the PDCCH, PDSCH, or both. When processing the first TRS and determining the QCL relationship, the UE 315 may configure itself to receive control signaling or data signaling from the base station 305-a (or an additional base station 305 of the first communication system) based on the information received in the first TRS.

[0090] At 340, the network device may send control signaling, data signaling, or a combination of both to the UE 315. In some cases, the PDCCH or PDSCH may be QCL with the first TRS. The UE 315 may receive data or control signaling based on having successfully processed the TRS and may thus maintain a connection with the network via the base station 305-a.

[0091] At 345, the UE 315 may initiate a handover. For example, the UE 315 may interrupt its connection with the base station 305-a and the UE 315 may establish a connection with the base station 305-b. In some examples, initiating a handover may be based on the UE 315 changing its location (e.g., from one coverage area to another, from one area of a first coverage area to a second area of the first coverage area, etc.). For example, the UE 315 on the HST may be located in a coverage area corresponding to the coverage area of a first network device supporting an NSA communication system. The HST may stop and the UE 315 may be located in a coverage area corresponding to the coverage areas of the first network device and a second network device, where the second network device supports an SA communication system (e.g., the user of the UE 315 may get off the HST). Additionally or alternatively, the handover may be initiated due to one or more of a signal from the base station 305-a or 305-b, an autonomous determination at the UE 315, meeting a threshold value, etc.

[0092] In some examples, the base station 305-b may not support the transmission of control messages including an indication of the TCI state. If the UE 315 is unable to determine the TCI state for receiving subsequent TRSs, the UE 315 may be unable to identify and process the subsequent TRSs, resulting in an increase in BLER, a decrease in signal throughput, a network connection interruption, etc. To mitigate such issues, the UE 315 may implement the techniques described herein at 355 and 360.

[0093] At 350, after the handover, the UE 315 may monitor control messages from the base station 305-b. In some cases, the base station 305-b may operate according to a second communication system, which may be an example of an SA system. The second communication system may not support the transmission of control signals including an explicit indication of the TCI state (e.g., for receiving TRSs). The UE 315 may monitor such control messages (e.g., MAC CE) from the base station 305-b. However, the base station 305-b may not send such control messages to the UE 315. Additionally or alternatively, the network device may send a control message to the UE 315, but the control message may not include an indication of one or more TCI states. In some cases, if the UE 315 does not identify the TCI state for receiving TRSs or subsequent signaling, the UE 315 may be unable to identify and process the subsequent TRSs, resulting in an increase in BLER, connection loss, etc. Therefore, the UE 315 may autonomously determine the TCI state configuration based on the status of one or more antenna port configuration conditions.

[0094] At 355, the UE 315 may determine whether one or more antenna port configuration conditions are met. The UE 315 may determine that the first antenna port configuration condition is met by monitoring the MAC CE indicating the TCI state. If the UE 315 fails to receive a control message, the UE 315 may determine that the first antenna port configuration condition is met. In some examples, the UE 315 may determine that the second antenna port configuration condition is met by determining an implicit downselection failure of the TCI. For example, if the UE 315 determines that multiple TCI states are configured (e.g., an implicit downselection failure of the TCI) and the UE 315 cannot continue to use a single configured TCI state, the UE 315 may determine that the second antenna port configuration condition is met. In some examples, the UE 315 may determine that the third antenna port configuration condition is met by verifying the presence or absence of one or more QCL relationships. For example, if the UE 315 can determine that there is no QCL relationship between one or more synchronization signals (e.g., SSB) and the TRS, the UE 315 may determine that the third antenna port configuration condition is met. If the UE 315 determines that one or more (e.g., all) antenna port configuration conditions are met, the UE 315 may use the most recently indicated TCI state before the handover. That is, at 360, the UE 315 may use the most recently used TCI state (e.g., the TCI state indicated at 320 before initiating the handover) to receive the next TRS from the base station 305-b. In some examples, if the UE 315 has reconfigured its TCI state after initiating the handover at 345, the UE 315 may reconfigure one or more antennas or antenna ports or both according to the first TCI state based on having determined that all antenna port configuration conditions are met.

[0095] At 360, the base station 305-b may send a second TRS. The UE 315 may use the most recently used TCI state (e.g., the TCI state indicated at 320) to receive and process the second TRS. The UE 315 may not reconfigure its antenna port based on determining that one or more (e.g., all) antenna port configuration conditions are met at 355 (e.g., may continue to monitor and receive signaling using the previously indicated TCI state).

[0096] At 365, the UE 315 may process the second TRS based on the TCI state indicated at 320 (before the handover). When processing the second TRS, the UE may identify the QCL relationship between the second TRS and one or more of the PDCCH and PDSCH. The UE 315 receives control signaling, data signaling, or both based on having processed the second TRS using the previously used TCI state.

[0097] At 370, the UE 315 may receive one or more of control signaling and data signaling based on having received a second TRS from the base station 305-b. Receiving control signaling, data signaling, or both may allow the UE 315 to continue communicating with the network via the base station 305-b without experiencing an increase in BLER.

[0098] In the previous description of the process flow 300, the operations performed by the UE 315, the base station 305-a, and the base station 305-b may be performed in a different order or at different times. Additionally or alternatively, some of the operations performed by the UE 315, the base station 305-a, and the base station 305-b may be performed simultaneously. Some operations may also be omitted from the process flow 300, or other operations may be added to the process flow 300. It should be understood that although the UE 315, the base station 305-a, and the base station 305-b are shown performing multiple operations of the process flow 300, any wireless device may perform the operations shown.

[0099] Figure 4 Block diagram 400 of a device 405 showing techniques supporting a transmission configuration indicator state switch for a handover process in accordance with aspects of the present disclosure is shown. The device 405 may be an example of aspects of the UE 115 described herein. The device 405 may include a receiver 410, a transmitter 415, and a communication manager 420. The device 405 may also include a processor. Each of these components may communicate with each other (e.g., via one or more buses).

[0100] The receiver 410 may provide a unit for receiving information (such as packets, user data, control information, or any combination thereof) associated with various information channels (e.g., control channels, data channels, information channels related to techniques for a transmission configuration indicator state switch for a handover process). The information may be passed to other components of the device 405. The receiver 410 may utilize a single antenna or a collection of multiple antennas.

[0101] The transmitter 415 may provide a unit for transmitting signals generated by other components of the device 405. For example, the transmitter 415 may transmit information (such as packets, user data, control information, or any combination thereof) associated with various information channels (e.g., control channels, data channels, information channels related to techniques for a transmission configuration indicator state switch for a handover process). In some examples, the transmitter 415 may be co-located with the receiver 410 in a transceiver component. The transmitter 415 may utilize a single antenna or a collection of multiple antennas.

[0102] The communication manager 420, the receiver 410, the transmitter 415, or various combinations or various components thereof can be examples of units for performing aspects of the techniques for transmission configuration indicator state switching for a handover process as described herein. For example, the communication manager 420, the receiver 410, the transmitter 415, or various combinations or components thereof can support methods for performing one or more of the functions described herein.

[0103] In some examples, the communication manager 420, the receiver 410, the transmitter 415, or various combinations or components thereof can be implemented in hardware (e.g., in communication management circuitry). The hardware can include a processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof configured to or otherwise supporting units for performing the functions described in this disclosure. In some examples, a processor and memory coupled to the processor can be configured to perform one or more of the functions described herein (e.g., by the processor executing instructions stored in the memory).

[0104] Additionally or alternatively, in some examples, the communication manager 420, the receiver 410, the transmitter 415, or various combinations or components thereof can be implemented with code executed by a processor (e.g., as communication management software or firmware). If implemented with code executed by a processor, the functions of the communication manager 420, the receiver 410, the transmitter 415, or various combinations or components thereof can be performed by a general purpose processor, a DSP, a central processing unit (CPU), an ASIC, an FPGA, or any combination of these or other programmable logic devices (e.g., configured to or otherwise supporting units for performing the functions described in this disclosure).

[0105] In some examples, the communication manager 420 can be configured to use the receiver 410, the transmitter 415, or both, or otherwise cooperate with the receiver 410, the transmitter 415, or both to perform various operations (e.g., receive, monitor, transmit). For example, the communication manager 420 can receive information from the receiver 410, send information to the transmitter 415, or be integrated in combination with the receiver 410, the transmitter 415, or both to receive information, send information, or perform various other operations as described herein.

[0106] According to examples disclosed herein, communication manager 420 may support wireless communication at a UE. For example, communication manager 420 may be configured to or otherwise support a unit for receiving a first tracking reference signal from a first network device in a first cell using a first transmission configuration indicator state in a set of transmission configuration indicator states. Communication manager 420 may be configured to or otherwise support a unit for initiating a handover from the first network device to a second network device. Communication manager 420 may be configured to or otherwise support a unit for receiving a second tracking reference signal from the second network device using the first transmission configuration indicator state, wherein using the first transmission configuration indicator state is based on meeting one or more antenna port configuration conditions.

[0107] By including or configuring communication manager 420 according to examples described herein, device 405 (e.g., a processor that controls or otherwise couples to receiver 410, transmitter 415, communication manager 420, or a combination thereof) may support techniques for a handover procedure, thereby reducing BLER, reducing the likelihood of connection failure, improving communication, increasing system efficiency, and improving the user experience.

[0108] Figure 5 Block diagram 500 of a device 505 supporting techniques for transmission configuration indicator state switching for a handover procedure in accordance with aspects of the present disclosure is shown. Device 505 may be an example of aspects of device 405 or UE 115 described herein. Device 505 may include a receiver 510, a transmitter 515, and a communication manager 520. Device 505 may also include a processor. Each of these components may communicate with each other (e.g., via one or more buses).

[0109] Receiver 510 may provide a unit for receiving information (such as packets, user data, control information, or any combination thereof) associated with various information channels (e.g., control channels, data channels, information channels related to techniques for transmission configuration indicator state switching for a handover procedure). The information may be passed to other components of device 505. Receiver 510 may utilize a single antenna or an array of multiple antennas.

[0110] Transmitter 515 may provide a unit for transmitting signals generated by other components of device 505. For example, transmitter 515 may transmit information (such as packets, user data, control information, or any combination thereof) associated with various information channels (e.g., control channels, data channels, information channels related to techniques for transmission configuration indicator state switching for a handover procedure). In some examples, transmitter 515 may be co-located with receiver 510 in a transceiver component. Transmitter 515 may utilize a single antenna or an array of multiple antennas.

[0111] Device 505 or its various components may be examples of units for performing aspects of techniques for transmission configuration indicator state switching for a handover process as described herein. For example, communication manager 520 may include a TCI state manager 525, a handover manager 530, or any combination thereof. Communication manager 520 may be an example of aspects of communication manager 420 as described herein. In some examples, communication manager 520 or its various components may be configured to perform various operations (e.g., receive, monitor, transmit) using receiver 510, transmitter 515, or both, or otherwise in cooperation with receiver 510, transmitter 515, or both. For example, communication manager 520 may receive information from receiver 510, send information to transmitter 515, or integrate with receiver 510, transmitter 515, or both to receive information, send information, or perform various other operations as described herein.

[0112] According to examples disclosed herein, communication manager 520 may support wireless communication at a UE. TCI state manager 525 may be configured to or otherwise support a unit for receiving a first tracking reference signal from a first network device in a first cell using a first transmission configuration indicator state from a set of transmission configuration indicator states. Handover manager 530 may be configured to or otherwise support a unit for initiating a handover from the first network device to a second network device. TCI state manager 525 may be configured to or otherwise support a unit for receiving a second tracking reference signal from the second network device using the first transmission configuration indicator state, wherein using the first transmission configuration indicator state is based on meeting one or more antenna port configuration conditions.

[0113] Figure 6 Block diagram 600 of a communication manager 620 supporting techniques for transmission configuration indicator state switching for a handover process in accordance with aspects of the present disclosure is shown. Communication manager 620 may be an example of aspects of communication manager 420, communication manager 520, or both as described herein. Communication manager 620 or its various components may be examples of units for performing aspects of techniques for transmission configuration indicator state switching for a handover process as described herein. For example, communication manager 620 may include a TCI state manager 625, a handover manager 630, a monitoring manager 635, a QCL manager 640, a TRS manager 645, a control message manager 650, or any combination thereof. Each of these components may communicate directly or indirectly with each other (e.g., via one or more buses).

[0114] According to examples disclosed herein, the communication manager 620 may support wireless communication at a UE. The TCI state manager 625 may be configured to or otherwise support a unit for receiving a first tracking reference signal from a first network device in a first cell using a first transmission configuration indicator state from a set of transmission configuration indicator states. The handover manager 630 may be configured to or otherwise support a unit for initiating a handover from the first network device to a second network device. In some examples, the TCI state manager 625 may be configured to or otherwise support a unit for receiving a second tracking reference signal from a second network device using the first transmission configuration indicator state, where using the first transmission configuration indicator state is based on meeting one or more antenna port configuration conditions.

[0115] In some examples, the monitoring manager 635 may be configured to or otherwise support a unit for monitoring, after initiating a handover, a control message including an indication of a second transmission configuration indicator state. In some examples, the monitoring manager 635 may be configured to or otherwise support a unit for failing to receive a control message based on the monitoring.

[0116] In some examples, the TCI state manager 625 may be configured to or otherwise support a unit for determining that the first transmission configuration indicator state is one of the transmission configuration indicator states in a set of transmission configuration indicator states, where the set of transmission configuration indicator states includes a plurality of transmission configuration indicator states.

[0117] In some examples, the QCL manager 640 may be configured to or otherwise support a unit for determining that there is no quasi - co - location relationship between one or more synchronization signals and at least one of the first tracking reference signal or the second tracking reference signal.

[0118] In some examples, the TRS manager 645 may be configured to or otherwise support a unit for processing the second tracking reference signal using the first transmission configuration indicator state. In some examples, the TRS manager 645 may be configured to or otherwise support a unit for receiving control signaling, data signaling, or both based on the processed tracking reference signal.

[0119] In some examples, to support initiating a handover, the handover manager 630 may be configured to or otherwise support a unit for initiating an intra - cell handover.

[0120] In some examples, to support initiating a handover, the handover manager 630 may be configured to or otherwise support a unit for initiating a handover from a non - stand - alone system to a stand - alone system.

[0121] In some examples, the first network device includes a base station, a repeater, a radio head, or any combination thereof associated with a high-speed train network deployment.

[0122] In some examples, the control message manager 650 may be configured to or otherwise support a unit for receiving, before initiating a handover, a control message from the first network device that includes an indication of a first transmission configuration indicator state, wherein receiving a first tracking reference signal using the first transmission configuration indicator state is based on receiving the control message.

[0123] Figure 7 FIG. shows a system 700 of a device 705 that includes techniques for supporting a transmission configuration indicator state switch for a handover procedure in accordance with aspects of the present disclosure. The device 705 may be an example of or include components of the device 405, the device 505, or the UE 115 described herein. The device 705 may wirelessly communicate with one or more base stations 105, UEs 75, or any combination thereof. The device 705 may include components for two-way voice and data communication, including components for sending and receiving communications, such as a communication manager 720, an input / output (I / O) controller 710, a transceiver 715, an antenna 725, a memory 730, code 735, and a processor 740. These components may be electronically communicated or otherwise (e.g., operatively, communicatively, functionally, electronically, electrically) coupled via one or more buses (e.g., bus 745).

[0124] The I / O controller 710 may manage input and output signals for the device 705. The I / O controller 710 may also manage peripheral devices not integrated into the device 705. In some cases, the I / O controller 710 may represent a physical connection or port to an external peripheral device. In some cases, the I / O controller 710 may utilize an operating system such as or another known operating system. Additionally or alternatively, the I / O controller 710 may represent a modem, a keyboard, a mouse, a touch screen, or similar device or interact with the above devices. In some cases, the I / O controller 710 may be implemented as part of a processor (such as the processor 740). In some cases, a user may interact with the device 705 via the I / O controller 710 or via hardware components controlled by the I / O controller 710.

[0125] In some cases, device 705 may include a single antenna 725. However, in some other cases, device 705 may have more than one antenna 725, which are capable of simultaneously transmitting or receiving multiple wireless transmissions. Transceiver 715 may communicate bidirectionally via one or more antennas 725, wired or wireless links as described herein. For example, transceiver 715 may represent a wireless transceiver and may communicate bidirectionally with another wireless transceiver. Transceiver 715 may also include a modem for modulating packets, providing the modulated packets to one or more antennas 725 for transmission, and demodulating packets received from one or more antennas 725. Transceiver 715 or transceiver 715 and one or more antennas 725 may be examples of transmitter 415, transmitter 515, receiver 410, receiver 510, or any combination thereof or components thereof as described herein.

[0126] Memory 730 may include random access memory (RAM) and read-only memory (ROM). Memory 730 may store computer-readable, computer-executable code 735 that includes instructions that, when executed by processor 740, cause device 705 to perform the various functions described herein. Code 735 may be stored in a non-transitory computer-readable medium (such as system memory or another type of memory). In some cases, code 735 may not be directly executable by processor 740 but may cause a computer (e.g., when compiled and executed) to perform the functions described herein. In some cases, in addition, memory 730 may also contain a basic input / output system (BIOS) that may control basic hardware or software operations, such as interactions with peripheral components or devices.

[0127] Processor 740 may include intelligent hardware devices (e.g., general-purpose processors, DSPs, CPUs, microcontrollers, ASICs, FPGAs, programmable logic devices, discrete gate or transistor logic components, discrete hardware components, or any combination thereof). In some cases, processor 740 may be configured to operate a memory array using a memory controller. In some other cases, the memory controller may be integrated into processor 740. Processor 740 may be configured to execute computer-readable instructions stored in a memory (e.g., memory 730) to cause device 705 to perform various functions (e.g., functions or tasks supporting techniques for transmission configuration indicator state switching for a handover procedure). For example, device 705 or components of device 705 may include processor 740 and memory 730 coupled to processor 740, and processor 740 and memory 730 are configured to perform the various functions described herein.

[0128] According to examples disclosed herein, communication manager 720 may support wireless communication at a UE. For example, communication manager 720 may be configured to or otherwise support a unit for receiving a first tracking reference signal from a first network device in a first cell using a first transmission configuration indicator state in a set of transmission configuration indicator states. Communication manager 720 may be configured to or otherwise support a unit for initiating a handover from the first network device to a second network device. Communication manager 720 may be configured to or otherwise support a unit for receiving a second tracking reference signal from the second network device using the first transmission configuration indicator state, wherein using the first transmission configuration indicator state is based on meeting one or more antenna port configuration conditions.

[0129] By including or configuring communication manager 720 according to examples described herein, device 705 may support techniques for a handover procedure, thereby reducing BLER, reducing the likelihood of connection failure, improving communication, increasing system efficiency, and improving the user experience.

[0130] In some examples, communication manager 720 may be configured to perform various operations (e.g., receive, monitor, transmit) using transceiver 715, one or more antennas 725, or any combination thereof or in cooperation therewith. Although communication manager 720 is shown as a separate component, in some examples, one or more functions described with reference to communication manager 720 may be supported or performed by processor 740, memory 730, code 735, or any combination thereof. For example, code 735 may include instructions executable by processor 740 to cause device 705 to perform aspects of techniques for transmission configuration indicator state switching for a handover procedure as described herein, or processor 740 and memory 730 may otherwise be configured to perform or support such operations.

[0131] Figure 8 A flowchart illustrating a method 800 for supporting transmission configuration indicator state switching for a handover procedure in accordance with aspects of the present disclosure is shown. The operations of method 800 may be implemented by a UE or components thereof as described herein. For example, the operations of method 800 may be performed by a UE 115 as described with reference to Figures 1 to 7 described. In some examples, the UE may execute an instruction set to control functional units of the UE to perform the described functions. Additionally or alternatively, the UE may use dedicated hardware to perform aspects of the described functions.

[0132] At 805, the method may include: receiving a first tracking reference signal from a first network device in a first cell using a first transmission configuration indicator state in a set of transmission configuration indicator states. The operation of 805 may be performed according to examples disclosed herein. In some examples, aspects of the operation of 805 may be performed by a TCI state manager 625 as described with reference to Figure 6 described.

[0133] At 810, the method may include: initiating a handover from the first network device to a second network device. The operation of 810 may be performed according to examples disclosed herein. In some examples, aspects of the operation of 810 may be performed by a handover manager 630 as described with reference to Figure 6 described.

[0134] At 815, the method may include: receiving a second tracking reference signal from the second network device using the first transmission configuration indicator state, wherein using the first transmission configuration indicator state is based on meeting one or more antenna port configuration conditions. The operation of 815 may be performed according to examples disclosed herein. In some examples, aspects of the operation of 815 may be performed by a TCI state manager 625 as described with reference to Figure 6 described.

[0135] Figure 9 FIG. shows a flowchart of a method 900 illustrating techniques that support transmission configuration indicator state switching for a handover procedure in accordance with aspects of the present disclosure. The operations of method 900 may be implemented by a UE or its components as described herein. For example, the operations of method 900 may be performed by a UE 115 as described with reference to Figures 1 to 7 described. In some examples, the UE may execute an instruction set to control functional units of the UE to perform the described functions. Additionally or alternatively, the UE may use dedicated hardware to perform aspects of the described functions.

[0136] At 905, the method may include: receiving a first tracking reference signal from a first network device in a first cell using a first transmission configuration indicator state in a set of transmission configuration indicator states. The operation of 905 may be performed according to examples disclosed herein. In some examples, aspects of the operation of 905 may be performed by a TCI state manager 625 as described with reference to Figure 6 described.

[0137] At 910, the method may include: initiating a handover from the first network device to a second network device. The operation of 910 may be performed according to examples disclosed herein. In some examples, aspects of the operation of 910 may be performed by a handover manager 630 as described with reference to Figure 6 described.

[0138] At 915, the method may include: after initiating a handover, monitoring a control message that includes an indication of a second transmission configuration indicator state. The operations at 915 may be performed according to examples disclosed herein. In some examples, aspects of the operations at 915 may be performed by a monitoring manager 635 as described with reference to Figure 6 the description.

[0139] At 920, the method may include: failing to receive a control message based on the monitoring. The operations at 920 may be performed according to examples disclosed herein. In some examples, aspects of the operations at 920 may be performed by a monitoring manager 635 as described with reference to Figure 6 the description.

[0140] At 925, the method may include: receiving a second tracking reference signal from a second network device using a first transmission configuration indicator state, where using the first transmission configuration indicator state is based on the failure to receive the control message. The operations at 925 may be performed according to examples disclosed herein. In some examples, aspects of the operations at 925 may be performed by a TCI state manager 625 as described with reference to Figure 6 the description.

[0141] Figure 10 FIG. 1000 is a flow diagram illustrating a method 1000 that supports techniques for transmission configuration indicator state switching for a handover procedure in accordance with aspects of the present disclosure. The operations of method 1000 may be implemented by a UE or components thereof as described herein. For example, the operations of method 1000 may be performed by a UE 115 as described with reference to Figures 1 to 7 the description. In some examples, the UE may execute an instruction set to control functional units of the UE to perform the described functions. Additionally or alternatively, the UE may use dedicated hardware to perform aspects of the described functions.

[0142] At 1005, the method may include: receiving a first tracking reference signal from a first network device in a first cell using a first transmission configuration indicator state from a set of transmission configuration indicator states. The operations at 1005 may be performed according to examples disclosed herein. In some examples, aspects of the operations at 1005 may be performed by a TCI state manager 625 as described with reference to Figure 6 the description.

[0143] At 1010, the method may include: initiating a handover from the first network device to the second network device. The operations at 1010 may be performed according to examples disclosed herein. In some examples, aspects of the operations at 1010 may be performed by a handover manager 630 as described with reference to Figure 6 the description.

[0144] At 1015, the method may include: determining that a first transmission configuration indicator state is one of a set of transmission configuration indicator states, where the set of transmission configuration indicator states includes a plurality of transmission configuration indicator states. The operation at 1015 may be performed according to the examples disclosed herein. In some examples, aspects of the operation at 1015 may be performed by a TCI state manager 625 as described with reference to Figure 6 described.

[0145] At 1020, the method may include: receiving a second tracking reference signal from a second network device using the first transmission configuration indicator state, where using the first transmission configuration indicator state is based on determining that the first transmission configuration indicator state is one of a set of transmission configuration indicator states. The operation at 1020 may be performed according to the examples disclosed herein. In some examples, aspects of the operation at 1020 may be performed by a TCI state manager 625 as described with reference to Figure 6 described.

[0146] Figure 11 FIG. 1100 is a flow diagram illustrating a method 1100 that supports techniques for switching transmission configuration indicator states for a handover procedure in accordance with aspects of the present disclosure. The operations of method 1100 may be implemented by a UE or components thereof as described herein. For example, the operations of method 1100 may be performed by a UE 115 as described with reference to Figures 1 to 7 described. In some examples, the UE may execute an instruction set to control functional units of the UE to perform the described functions. Additionally or alternatively, the UE may use dedicated hardware to perform aspects of the described functions.

[0147] At 1105, the method may include: receiving a first tracking reference signal from a first network device in a first cell using a first transmission configuration indicator state of a set of transmission configuration indicator states. The operation at 1105 may be performed according to the examples disclosed herein. In some examples, aspects of the operation at 1105 may be performed by a TCI state manager 625 as described with reference to Figure 6 described.

[0148] At 1110, the method may include: initiating a handover from the first network device to the second network device. The operation at 1110 may be performed according to the examples disclosed herein. In some examples, aspects of the operation at 1110 may be performed by a handover manager 630 as described with reference to Figure 6 described.

[0149] At 1115, the method may include: determining that there is no quasi - co - location relationship between one or more synchronization signals and at least one of a first tracking reference signal or a second tracking reference signal. The operation of 1115 may be performed according to examples disclosed herein. In some examples, aspects of the operation of 1115 may be performed by a QCL manager 640 as described with reference to Figure 6 described.

[0150] At 1120, the method may include: receiving a second tracking reference signal from a second network device using a first transmission configuration indicator state, wherein using the first transmission configuration indicator state is based on determining that there is no quasi - co - location relationship between one or more synchronization signals and at least one of a first tracking reference signal or a second tracking reference signal. The operation of 1120 may be performed according to examples disclosed herein. In some examples, aspects of the operation of 1120 may be performed by a TCI state manager 625 as described with reference to Figure 6 described.

[0151] Aspect 1: A method for wireless communication at a UE, comprising: receiving a first tracking reference signal from a first network device in a first cell using a first transmission configuration indicator state in a set of transmission configuration indicator states; initiating a handover from the first network device to a second network device; and receiving a second tracking reference signal from the second network device using the first transmission configuration indicator state, wherein using the first transmission configuration indicator state is at least partially based on meeting one or more antenna port configuration conditions.

[0152] Aspect 2: The method according to aspect 1, further comprising: after initiating the handover, monitoring a control message including an indication of a second transmission configuration indicator state; and failing to receive the control message at least partially based on the monitoring.

[0153] Aspect 3: The method according to any one of aspects 1 to 2, further comprising: determining that the first transmission configuration indicator state is one of the transmission configuration indicator states in the set of transmission configuration indicator states.

[0154] Aspect 4: The method according to any one of aspects 1 to 3, further comprising: determining that there is no quasi - co - location relationship between one or more synchronization signals and at least one of the first tracking reference signal or the second tracking reference signal.

[0155] Aspect 5: The method according to any one of aspects 1 to 4, further comprising: using the first transmission configuration indicator state to process the second tracking reference signal; and receiving control signaling, data signaling, or both at least partially based on the processed tracking reference signal.

[0156] Aspect 6: The method according to any one of Aspects 1 to 5, wherein initiating the handover includes: initiating an intra-cell handover.

[0157] Aspect 7: The method according to any one of Aspects 1 to 6, wherein initiating the handover includes: initiating a handover from a non-standalone system to a standalone system.

[0158] Aspect 8: The method according to any one of Aspects 1 to 7, wherein the first network device includes a base station, a repeater, a radio head, or any combination thereof associated with a high-speed train network deployment.

[0159] Aspect 9: The method according to any one of Aspects 1 to 8, further comprising: receiving, before initiating the handover, a control message from the first network device that includes an indication of the first transmission configuration indicator state, wherein receiving the first tracking reference signal using the first transmission configuration indicator state is at least partially based on receiving the control message.

[0160] Aspect 10: An apparatus for wireless communication at a UE, comprising: a processor; a memory coupled to the processor; and instructions stored in the memory and executable by the processor to cause the apparatus to perform the method according to any one of Aspects 1 to 9.

[0161] Aspect 11: An apparatus for wireless communication at a UE, comprising at least one unit for performing the method according to any one of Aspects 1 to 9.

[0162] Aspect 12: A non-transitory computer-readable medium storing code for wireless communication at a UE, the code including instructions executable by a processor to perform the method according to any one of Aspects 1 to 9.

[0163] It should be noted that the methods described herein describe possible implementations, and the operations and steps may be rearranged or otherwise modified, and other implementations are possible. Additionally, aspects from two or more methods may be combined.

[0164] Although aspects of LTE, LTE-A, LTE-A Pro, or NR systems may be described for purposes of example and the LTE, LTE-A, LTE-A Pro, or NR terminology may be used in much of the description, the techniques described herein are applicable beyond LTE, LTE-A, LTE-A Pro, or NR networks. For example, the described techniques may be applicable to a variety of other wireless communication systems such as Ultra Mobile Broadband (UMB), Institute of Electrical and Electronics Engineers (IEEE) 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, Flash-OFDM, and other systems and radio technologies not explicitly mentioned herein.

[0165] The information and signals described herein may be represented using any of a variety of different technologies and methods. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be referred to throughout the description may be represented by voltage, current, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

[0166] The various illustrative blocks and components described in connection with the disclosure herein may be implemented or performed with a general purpose processor, DSP, ASIC, CPU, FPGA, or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. The general purpose processor may be a microprocessor, but in the alternative, the processor may be any processor, controller, microcontroller, or state machine. The processor may also be implemented as a combination of computing devices (e.g., a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration).

[0167] The functions described herein may be implemented in hardware, software executed by a processor, firmware, or any combination thereof. If implemented in software executed by a processor, the functions may be stored on or transmitted via a computer-readable medium as one or more instructions or code. Other examples and implementations are within the scope of the present disclosure and the appended claims. For example, due to the nature of software, the functions described herein may be implemented using software executed by a processor, hardware, firmware, hardwiring, or any combination of these items. The features implementing the functions may also be physically located at various positions, including being distributed such that portions of the functions are implemented at different physical locations.

[0168] A computer-readable medium includes both a non-transitory computer storage medium and a communication medium, where the communication medium includes any medium that facilitates the transfer of a computer program from one place to another. The non-transitory storage medium can be any available medium that can be accessed by a general-purpose or special-purpose computer. By way of example and not limitation, the non-transitory computer-readable medium can include RAM, ROM, electrically erasable programmable ROM (EEPROM), flash memory, compact disc read-only memory (CD-ROM) or other optical disc storage, magnetic disk storage or other magnetic storage devices, or any other non-transitory medium that can be used to carry or store the desired program code units in the form of instructions or data structures and that can be accessed by a general-purpose or special-purpose computer, or a general-purpose or special-purpose processor. Additionally, any connection is properly termed a computer-readable medium. For example, if software is transmitted from a website, server, or other remote source using coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwave, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of computer-readable medium. As used herein, disk and disc include CD, laser disc, optical disc, digital versatile disc (DVD), floppy disk, and Blu-ray disc, where disks typically reproduce data magnetically, while discs use lasers to optically reproduce data. Combinations of the above are also included within the scope of computer-readable medium.

[0169] As used herein (including in the claims), the "or" as used in a list of items (e.g., a list of items that ends with a phrase such as "at least one of" or "one or more of") indicates an inclusive list, such that a list of, for example, at least one of A, B, or C means A or B or C or AB or AC or BC or ABC (i.e., A and B and C). Additionally, as used herein, the phrase "based on" should not be construed as a reference to a closed set of conditions. For example, without departing from the scope of the present disclosure, an example step described as "based on condition A" can be based on both condition A and condition B. In other words, as used herein, the phrase "based on" should be interpreted in the same manner as the phrase "at least partially based on".

[0170] In the figures, similar components or features may have the same reference numerals. Additionally, various components of the same type can be distinguished by following the reference numeral with a dash and a second numeral, which is used to distinguish among similar components. If only the first reference numeral is used in the specification, the description applies to any one of the similar components having the same first reference numeral, regardless of the second reference numeral or any other subsequent reference numerals.

[0171] The description of example configurations has been presented in conjunction with the illustrations described herein and does not represent all examples that may be implemented or that are within the scope of the claims. The term "example" as used herein means "serving as an example, instance, or illustration" and not "preferred" or "advantageous over other examples." For the purpose of providing an understanding of the described technology, the detailed description includes specific details. However, the technology may be practiced without these specific details. In some instances, well-known structures and devices are shown in block diagram form in order to avoid obscuring the concepts of the described examples.

[0172] The description herein is provided to enable a person skilled in the art to make or use the present disclosure. Various modifications to the present disclosure will be apparent to those skilled in the art, and the general principles defined herein may be applied to other variations without departing from the scope of the present disclosure. Thus, the present disclosure is not limited to the examples and designs described herein but is accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for wireless communication at a user equipment (UE), comprising: receiving a first tracking reference signal from a first network device in a first cell using a first transmission configuration indicator state in a set of transmission configuration indicator states; initiating a handover from the first network device to a second network device; and receiving a second tracking reference signal from the second network device using the first transmission configuration indicator state, wherein using the first transmission configuration indicator state is at least partially based on meeting one or more antenna port configuration conditions.

2. The method according to claim 1, further comprising: after initiating the handover, monitoring a control message including an indication of a second transmission configuration indicator state; and failing to receive the control message at least partially based on the monitoring.

3. The method according to claim 1, further comprising: determining that the first transmission configuration indicator state is one of the transmission configuration indicator states in the set of transmission configuration indicator states, wherein the set of transmission configuration indicator states includes a plurality of transmission configuration indicator states.

4. The method according to claim 1, further comprising: determining that there is no quasi - co - location relationship between one or more synchronization signals and at least one of the first tracking reference signal or the second tracking reference signal.

5. The method according to claim 1, further comprising: processing the second tracking reference signal using the first transmission configuration indicator state; and receiving control signaling, data signaling, or both at least partially based on the processed tracking reference signal.

6. The method according to claim 1, wherein, initiating the handover includes: initiating an intra - cell handover.

7. The method according to claim 1, wherein, initiating the handover includes: initiating a handover from a non - stand - alone system to a stand - alone system.

8. The method according to claim 1, wherein, the first network device includes a base station, a repeater, a radio head, or any combination thereof associated with a high - speed train network deployment.

9. The method according to claim 1, further comprising: receiving, before initiating the handover, a control message from the first network device including an indication of the first transmission configuration indicator state, wherein receiving the first tracking reference signal using the first transmission configuration indicator state is at least partially based on receiving the control message.

10. An apparatus for wireless communication at a user equipment (UE), comprising: a processor; a memory coupled to the processor; and instructions stored in the memory and executable by the processor to cause the apparatus to perform the following operations: receiving a first tracking reference signal from a first network device in a first cell using a first transmission configuration indicator state in a set of transmission configuration indicator states; initiating a handover from the first network device to a second network device; and receiving a second tracking reference signal from the second network device using the first transmission configuration indicator state, wherein using the first transmission configuration indicator state is at least partially based on meeting one or more antenna port configuration conditions.

11. The apparatus according to claim 10, wherein, the instructions can also be executed by the processor to cause the apparatus to perform the following operations: after initiating the handover, monitor a control message including an indication of a second transmission configuration indicator state; and fail to receive the control message at least in part based on the monitoring.

12. The apparatus according to claim 10, wherein, the instructions can also be executed by the processor to cause the apparatus to perform the following operations: determine that the first transmission configuration indicator state is one of a set of transmission configuration indicator states, wherein the set of transmission configuration indicator states includes a plurality of transmission configuration indicator states.

13. The apparatus according to claim 10, wherein, the instructions can also be executed by the processor to cause the apparatus to perform the following operations: determine that there is no quasi - co - location relationship between one or more synchronization signals and at least one of the first tracking reference signal or the second tracking reference signal.

14. The apparatus according to claim 10, wherein, the instructions can also be executed by the processor to cause the apparatus to perform the following operations: use the first transmission configuration indicator state to process the second tracking reference signal; and receive control signaling, data signaling, or both at least in part based on the processed tracking reference signal.

15. The apparatus according to claim 10, wherein, the instruction for initiating the handover can be executed by the processor to cause the apparatus to perform the following operation: initiate an intra - cell handover.

16. The apparatus according to claim 10, wherein, the instruction for initiating the handover can be executed by the processor to cause the apparatus to perform the following operation: initiate a handover from a non - stand - alone system to a stand - alone system.

17. The apparatus according to claim 10, wherein, the first network device includes a base station, a repeater, a radio head, or any combination thereof associated with a high - speed train network deployment.

18. The apparatus according to claim 10, wherein, the instructions can also be executed by the processor to cause the apparatus to perform the following operations: receive, before initiating the handover, a control message from the first network device including an indication of the first transmission configuration indicator state, wherein receiving the first tracking reference signal using the first transmission configuration indicator state is at least in part based on receiving the control message.

19. An apparatus for wireless communication at a user equipment (UE), comprising: a unit for receiving a first tracking reference signal from a first network device in a first cell using a first transmission configuration indicator state in a set of transmission configuration indicator states; a unit for initiating a handover from the first network device to a second network device; and a unit for receiving a second tracking reference signal from the second network device using the first transmission configuration indicator state, wherein using the first transmission configuration indicator state is at least in part based on meeting one or more antenna port configuration conditions.

20. The apparatus according to claim 19, further comprising: a unit for monitoring, after initiating the handover, a control message including an indication of a second transmission configuration indicator state; and a unit for failing to receive the control message at least partially based on the monitoring.

21. The apparatus according to claim 19, further comprising: a unit for determining that the first transmission configuration indicator state is one transmission configuration indicator state in a set of transmission configuration indicator states, wherein the set of transmission configuration indicator states includes a plurality of transmission configuration indicator states.

22. The apparatus according to claim 19, further comprising: a unit for determining that there is no quasi co-location relationship between one or more synchronization signals and at least one of the first tracking reference signal or the second tracking reference signal.

23. The apparatus according to claim 19, further comprising: a unit for processing the second tracking reference signal using the first transmission configuration indicator state; and a unit for receiving control signaling, data signaling, or both at least partially based on the processed tracking reference signal.

24. The apparatus according to claim 19, wherein the unit for initiating the handover includes: a unit for initiating an intra-cell handover.

25. The apparatus according to claim 19, wherein the unit for initiating the handover includes: a unit for initiating a handover from a non-standalone system to a standalone system.

26. The apparatus according to claim 19, further comprising: a unit for receiving, before initiating the handover, from the first network device a control message including an indication of the first transmission configuration indicator state, wherein receiving the first tracking reference signal using the first transmission configuration indicator state is at least partially based on receiving the control message.

27. A non-transitory computer-readable medium storing code for wireless communication at a user equipment (UE), the code including instructions executable by a processor to perform the following operations: receiving a first tracking reference signal from a first network device in a first cell using a first transmission configuration indicator state in a set of transmission configuration indicator states; initiating a handover from the first network device to a second network device; and receiving a second tracking reference signal from the second network device using the first transmission configuration indicator state, wherein using the first transmission configuration indicator state is at least partially based on meeting one or more antenna port configuration conditions.

28. The non-transitory computer-readable medium according to claim 27, wherein the instructions are further executable by the processor to perform the following operations: monitoring, after initiating the handover, a control message including an indication of a second transmission configuration indicator state; and failing to receive the control message at least partially based on the monitoring.

29. The non-transitory computer-readable medium according to claim 27, wherein the instructions are further executable by the processor to perform the following operations: Determine that the first transmission configuration indicator state is one of the transmission configuration indicator states in the set of transmission configuration indicator states, where the set of transmission configuration indicator states includes a plurality of transmission configuration indicator states.

30. The non-transitory computer-readable medium according to claim 27, wherein, the instructions are further executable by the processor to perform the following operations: Determine that there is no quasi-co-location relationship between one or more synchronization signals and at least one of the first tracking reference signal or the second tracking reference signal.

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