Techniques for flexible reference signal patterns in wireless communication systems

Abstract

Methods, systems, and devices for wireless communications are described. A user equipment (UE) may receive a first tracking reference signal configuration and a second tracking reference signal configuration from a base station. The first tracking reference signal configuration may include a first set of parameters, and the second tracking reference signal configuration may include a second set of parameters. The UE, the base station, or both may identify an indicator for a selection result from among the first tracking reference signal configuration and the second tracking reference signal configuration. The UE may receive a tracking reference signal according to the first tracking reference signal configuration or the second tracking reference signal configuration from the base station and based on the identified indicator for the selection result.

Description

[0001] Cross-references

[0002] This patent application claims the benefit of U.S. Provisional Patent Application No. 63 / 072,010, filed by Ma et al. on August 28, 2020, entitled “TECHNIQUES FOR FLEXIBLE REFERENCE SIGNAL PATTERNS IN WIRELESS COMMUNICATIONS SYSTEMS,” and U.S. Patent Application No. 17 / 375,944, filed by Ma et al. on July 14, 2021, entitled “TECHNIQUES FOR FLEXIBLE REFERENCE SIGNAL PATTERNS IN WIRELESS COMMUNICATIONS SYSTEMS,” each of which is assigned to the assignee of this application. Technical Field

[0003] The following generally relates to wireless communications, including techniques for flexible reference signal patterns in wireless communication systems. Background Art

[0004] Wireless communication systems are widely deployed to provide various types of communication content, such as voice, video, packet data, messaging, broadcasting, etc. These systems can support communication with multiple users by sharing available system resources (e.g., time, frequency and power). Examples of such multiple access systems include fourth generation (4G) systems such as long term evolution (LTE) systems, advanced LTE (LTE-A) systems or LTE-A Pro systems, and fifth generation (5G) systems that may be referred to as new radio (NR) systems. These systems may use 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 extended orthogonal frequency division multiplexing (DFT-S-OFDM). A wireless multiple access communication system may include one or more base stations or one or more network access nodes, each base station or network access node supporting communication of multiple communication devices simultaneously, wherein the communication device may also be referred to as user equipment (UE).

[0005] Some wireless communication systems may support reference signals, such as tracking reference signals. Such reference signals may enable devices in the wireless communication system to estimate channel conditions, frequency errors, etc. However, conventional techniques for reference signals may be insufficient. Summary of the invention

[0006] The described technology relates to improved methods, systems, devices and apparatuses for supporting technology for flexible reference signal modes in wireless communication systems. In general, the described technology enables devices of wireless communication systems to implement one or more tracking reference signal (TRS) configurations, for example, based on one or more indications, which can bring improved accuracy for frequency offset estimation (e.g., in relatively high frequency bands), enhanced flexibility of the system, reduced processing and system overhead, or any combination thereof, and other advantages. For example, a base station can configure a user equipment with a TRS configuration set (e.g., the base station can send a first TRS configuration and a second TRS configuration to the UE). The UE can receive a tracking reference signal from the base station based on a selected TRS configuration based on an indicator for a selection result from the TRS configuration set. For example, in addition to other examples of selecting a TRS configuration based on an indicator, the UE can select a TRS configuration based on an identified bandwidth portion, an indicator received via control signaling, a non-periodic TRS trigger, an indicator received during a random access channel process, an identified transmission configuration indicator state, or any combination thereof. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1

[0013] An example of a system for wireless communications that supports techniques for flexible reference signal patterns in wireless communication systems in accordance with aspects of the present disclosure is shown.

[0008] Figure 2

[0013] An example of a wireless communication system supporting techniques for flexible reference signal patterns in a wireless communication system in accordance with aspects of the present disclosure is shown.

[0009] Figures 3 to 5

[0026] Examples of resource schemes supporting techniques for flexible reference signal patterns in wireless communication systems in accordance with aspects of the present disclosure are shown.

[0010] Figure 6 An example of a process flow supporting techniques for flexible reference signal modes in a wireless communication system in accordance with aspects of the present disclosure is shown.

[0011] Figure 7

[0026] Examples of resource schemes supporting techniques for flexible reference signal patterns in wireless communication systems in accordance with aspects of the present disclosure are shown.

[0012] Figure 8 An example of a process flow supporting techniques for flexible reference signal modes in a wireless communication system in accordance with aspects of the present disclosure is shown.

[0013] Fig. 9 and 10A block diagram of a device supporting techniques for flexible reference signal patterns in a wireless communication system is shown in accordance with aspects of the present disclosure.

[0014] Fig.11 A block diagram of a communications manager supporting techniques for flexible reference signal patterns in a wireless communication system is shown in accordance with aspects of the present disclosure.

[0015] Fig.12

[0013] Diagram of a system including devices supporting techniques for flexible reference signal patterns in a wireless communication system in accordance with aspects of the present disclosure is shown.

[0016] Fig.13 and 14 A block diagram of a device supporting techniques for flexible reference signal patterns in a wireless communication system is shown in accordance with aspects of the present disclosure.

[0017] Fig.15 A block diagram of a communications manager supporting techniques for flexible reference signal patterns in a wireless communication system is shown in accordance with aspects of the present disclosure.

[0018] Fig.16

[0013] Diagram of a system including devices supporting techniques for flexible reference signal patterns in a wireless communication system in accordance with aspects of the present disclosure is shown.

[0019] Figures 17 to 20 A flow chart illustrating a method of supporting techniques for flexible reference signal patterns in a wireless communication system in accordance with aspects of the present disclosure. DETAILED DESCRIPTION

[0020] Some wireless communication systems (e.g., new radio (NR)) may support reference signals that enable user equipment (UE) and base stations to estimate channel conditions, enhance the reliability or efficiency of communications, etc. For example, a tracking reference signal (TRS) may be implemented by a user equipment (UE) and a base station for timing tracking, frequency tracking, etc. As an illustrative example, a UE may receive a TRS from a base station and estimate a frequency offset based on the TRS. However, in some cases, a UE may experience a relatively high amount of frequency error (e.g., for higher frequency bands, such as FR2x, FR4, etc.), which may reduce the accuracy of the frequency offset estimate.

[0021] According to the techniques described herein, a UE may be configured with multiple TRS configurations (e.g., multiple TRS modes according to corresponding parameter sets). For example, a base station may configure multiple TRS configurations at a UE. The described techniques may enable a UE to select from multiple TRS configurations (e.g., switch between multiple TRS configurations). In some examples, different TRS configurations may be implemented depending on parameter examples such as a digital scheme, an operating signal-to-noise ratio (SNR), a residual error threshold, or a combination thereof, which may result in enhanced accuracy for frequency offset estimation and flexible TRS modes in the system, as well as other advantages.

[0022] For example, the base station may configure the UE with a first TRS configuration (e.g., a first TRS mode according to a first parameter set) and a second TRS configuration (e.g., a second TRS mode according to a second parameter set). The UE may identify an indicator for a selection result from among these TRS configurations. The UE may receive the TRS according to the selected TRS configuration based on the identified indicator. In some examples, the UE may select the TRS configuration based on the identified bandwidth part. For example, the first bandwidth part may correspond to the first TRS configuration and the second bandwidth part may correspond to the second TRS configuration, and the UE may select the corresponding TRS configuration based on whether the identified bandwidth part is the first bandwidth part or the second bandwidth part. Additionally or alternatively, the base station may send an indicator to switch the TRS configuration via control signaling (e.g., via radio resource control (RRC) configuration signaling, medium access control (MAC) control element (CE) signaling, downlink control information, etc.). The UE may switch from the first TRS configuration to the second TRS configuration according to the indicator in the control signaling, which may enable the base station to update the UE with different TRS configurations within the same bandwidth part. .

[0023] In some examples, the base station may configure the UE with a default TRS configuration (e.g., for periodic resources) and may send a non-periodic TRS trigger to indicate a different TRS configuration (e.g., for non-periodic resources indicated by the TRS trigger). In some examples, the base station may send a message indicating the TRS configuration as part of a random access channel (RACH) process (e.g., message 2 or message B in a 4-step RACH process or a 2-step RACH process, respectively). In some examples, the UE may select a TRS configuration based on an identified transmission configuration indicator (TCI) state for different beams (e.g., the TCI state may correspond to a corresponding TRS configuration). Various aspects of the present disclosure are initially described in the context of a wireless communication system. Various aspects of the present disclosure are also described in the context of a resource scheme and a processing flow. Various aspects of the present disclosure are also illustrated and described by and with reference to apparatus diagrams, system diagrams, and flow charts of technologies related to flexible reference signal modes in wireless communication systems.

[0024] Figure 1 An example of a wireless communication system 100 supporting techniques for flexible reference signal modes in a wireless communication system in accordance with aspects of the present disclosure is shown. The wireless communication system 100 includes one or more base stations 105, one or more UEs 115, and a core network 130. In some examples, the wireless communication system 100 may be a long term evolution (LTE) network, an advanced LTE (LTE-A) network, an LTE-A Pro network, or a new radio (NR) network. In some cases, the wireless communication system 100 may support enhanced broadband communications, ultra-reliable (e.g., mission-critical) communications, low-latency communications, communications with low-cost and low-complexity devices, or a combination thereof.

[0025] The base stations 105 may be dispersed throughout a geographic area to form the 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 over which the UEs 115 and the base stations 105 may establish one or more communication links 125. The coverage area 110 may be an example of a geographic area over which the base stations 105 and the UEs 115 support communication of signals according to one or more radio access technologies.

[0026] The UEs 115 may be dispersed throughout the coverage area 110 of the wireless communication system 100, and each UE 115 may be stationary, mobile, or both at different times. The UEs 115 may be devices of different forms or with different capabilities. Figure 1 Some example UEs 115 are shown. Figure 1As shown, the UE 115 described herein may communicate 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).

[0027] 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 with each other directly (e.g., directly between the base stations 105), or indirectly (e.g., via the core network 130), or both via 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.

[0028] 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 transceiver station, a radio base station, an access point, a radio transceiver, a Node B, an eNode B (eNB), a next generation Node B or a giga Node B (any of which may be referred to as a gNB), a Home Node B, a Home eNode B, or other suitable terminology.

[0029] UE 115 may include or may be referred to as a mobile device, a wireless device, a remote device, a handheld device or a user device, or some other suitable term, where a "device" may also be referred to as a unit, a station, a terminal or a client, etc. UE 115 may also include or may be referred to as a personal electronic device, such as a cellular phone, a personal digital assistant (PDA), a tablet computer, a laptop computer, or a personal computer. In some examples, UE 115 may also include or be referred to as a wireless local loop (WLL) station, an Internet of Things (IoT) device, an Internet of Everything (IoE) device, or a machine type communication (MTC) device, etc., which may be implemented in various objects such as devices, or vehicles, meters, etc.

[0030] The UE 115 described herein is capable of communicating with various types of devices, such as Figure 1 As shown, various types of devices such as other UEs 115 that may sometimes act as relays, as well as base stations 105 and network equipment including macro eNBs or gNBs, small cell eNBs or gNBs, or relay base stations, etc.

[0031] The UE 115 and the base station 105 can communicate with each other wirelessly via one or more communication links 125 through one or more carriers. The term "carrier" may refer to a set of radio 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 spectrum band (e.g., a bandwidth portion (BWP)) that operates according to 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 operations for 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 the 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 frequency division duplex (FDD) and time division duplex (TDD) component carriers.

[0032] The signal waveform transmitted on the carrier may be composed of multiple subcarriers (e.g., using multi-carrier modulation (MCM) techniques, such as orthogonal frequency division multiplexing (OFDM) or discrete Fourier transform spread OFDM (DFT-S-OFDM)). In a system employing MCM techniques, a resource element may be composed of a symbol period (e.g., the duration of a modulation symbol) and a subcarrier, where the symbol period and the subcarrier spacing are inversely proportional. The number of bits carried by each resource element may depend on the modulation scheme (e.g., the order of the modulation scheme, the coding rate of the modulation scheme, or both). Therefore, the more resource elements received by UE 115 and the higher the order of the modulation scheme, the higher the data rate of UE 115 may be. Wireless communication resources may refer to a combination of radio spectrum resources, time resources, and spatial resources (e.g., spatial layers or beams), and the use of multiple spatial layers may further improve the data rate or data integrity used to communicate with UE 115.

[0033] One or more digital schemes for a carrier may be supported, where the digital scheme may include a subcarrier spacing (Δf) and a cyclic prefix. A carrier may be divided into one or more BWPs with the same or different digital schemes. In some examples, a UE 115 may be configured with multiple BWPs. In some examples, a single BWP for a carrier may be active at a given time, and communications by a UE 115 may be limited to the one or more active BWPs.

[0034] The time interval of the base station 105 or the UE 115 may be expressed as a multiple of a basic time unit, which may be, for example, T s =1 / (Δf max·N f ) seconds sampling period, where Δf max It can indicate the maximum subcarrier spacing supported, N f The maximum supported discrete Fourier transform (DFT) size may be indicated. The time intervals of the communication resources may be organized according to radio frames each having a specified duration (e.g., 10 milliseconds (ms)). Each radio frame may be identified by a system frame number (SFN) (e.g., ranging from 0 to 1023).

[0035] Each frame may include a plurality of consecutively numbered subframes or time slots, and each subframe or time slot may have the same duration. In some examples, a frame may be divided into subframes (e.g., in the time domain), and each subframe may be further divided into a plurality of time slots. Alternatively, each frame may include a variable number of time slots, and the number of time slots may depend on the subcarrier spacing. Each time slot may include a plurality of symbol periods (e.g., depending on the length of a cyclic prefix prepended to each symbol period). In some wireless communication systems 100, a time slot may be further divided into a plurality of mini-time slots containing one or more symbols. In addition to the cyclic prefix, each symbol period may contain one or more (e.g., N f The duration of a symbol period may depend on the subcarrier spacing or the operating frequency band.

[0036] A subframe, a time slot, a mini-time slot, or a symbol may be a minimum 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 minimum scheduling unit of the wireless communication system 100 may be dynamically selected (e.g., in bursts of short TTIs (sTTIs)).

[0037] Physical channels may be multiplexed on a carrier according to various techniques. Physical control channels and physical data channels may be multiplexed on a downlink carrier, for example, using one or more of a time division multiplexing (TDM) technique, a frequency division multiplexing (FDM) technique, or a hybrid TDM-FDM technique. A control region (e.g., a control resource set (CORESET)) for a physical control channel may be defined by a plurality of symbol periods and may be extended across a system bandwidth or a subset of a system bandwidth of a carrier. One or more control regions (e.g., CORESETs) may be configured for a group of UEs 115. For example, one or more of UEs 115 may monitor or search a control region for control information according to one or more search space sets, and each search space set may include one or more control channel candidates with one or more aggregation levels arranged in a cascaded manner. The aggregation level of a control channel candidate may refer to the number of control channel resources (e.g., control channel elements (CCEs)) associated with a coding information format for a given payload size. A search space set may include a common search space set configured for sending control information to a plurality of UEs 115 and a UE-specific search space set for sending control information to a specific UE 115.

[0038] In some examples, the base stations 105 may be mobile and thus provide communication coverage for mobile geographic coverage areas 110. In some examples, different geographic coverage areas 110 associated with different technologies may overlap, but the different geographic coverage areas 110 may be supported by the same base station 105. In other examples, overlapping geographic coverage areas 110 associated with different technologies may be supported by different base stations 105. The wireless communication system 100 may include, for example, a heterogeneous network in which different types of base stations 105 provide coverage for various geographic coverage areas 110 using the same or different radio access technologies.

[0039] The wireless communication system 100 can be configured to support ultra-reliable communication or low-latency communication, or various combinations thereof. For example, the wireless communication system 100 can be configured to support ultra-reliable low latency communication (URLLC) or mission-critical communication. UE 115 can be designed to support ultra-reliable, low-latency or critical functions (e.g., mission-critical functions). Ultra-reliable communication can include private communication or group communication, and can 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 can include prioritization of services, and mission-critical services can be used for public safety or general commercial applications. The terms ultra-reliable, low-latency, mission-critical, and ultra-reliable low-latency can be used interchangeably herein.

[0040] In some examples, UE 115 can also communicate directly with other UE 115 via device-to-device (D2D) communication links 135 (e.g., using a peer-to-peer (P2P) protocol or a D2D protocol). One or more UE 115 using D2D communication can be within the geographic coverage area 110 of the base station 105. Other UEs 115 in such a group can be outside the geographic coverage area 110 of the base station 105, or cannot receive transmissions from the base station 105. In some examples, the grouped UEs 115 communicating via D2D communication can utilize a one-to-many (1:M) system, in which each UE 115 transmits to each other UE 115 in the group. In some examples, the base station 105 facilitates scheduling resources for D2D communication. In other cases, D2D communication is performed between UEs 115 without involving the base station 105.

[0041] The core network 130 may provide user authentication, access authorization, tracking, Internet Protocol (IP) connection, and other access, routing, or mobility functions. The core network 130 may be an evolved packet core (EPC) or a 5G core (5GC), which may 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 or interconnects to an external network (e.g., a serving gateway (S-GW), a packet data network (PDN) gateway (P-GW), a user plane function (UPF)). The control plane entity may manage non-access stratum (NAS) functions such as mobility, authentication, and bearer management for UE 115 served by a base station 105 associated with the core network 130. User IP packets may be transmitted through the user plane entity, which may provide IP address allocation and other functions. The user plane entity may be connected to a network operator IP service 150. The network operator IP services 150 may include access to the Internet, an intranet, an IP Multimedia Subsystem (IMS), or packet switched (PS) streaming services.

[0042] At least some network devices, such as base stations 105, may include subcomponents such as access network entities 140, which may be examples of access node controllers (ANCs). Each access network entity 140 may communicate with the UE 115 through several other access network transport entities 145, which may be referred to as radio heads, smart radio heads, or transmit / receive points. Each access network transport entity 145 may include one or more antenna panels. In some configurations, the various functions of each access network entity 140 or base station 105 may be distributed among various network devices (e.g., radio heads and ANCs) or merged into a single network device (e.g., base station 105).

[0043] 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). Typically, the region from 300MHz to 3GHz is referred to as the ultra-high frequency (UHF) region or decimeter band because the wavelength ranges from about one decimeter to one meter long. UHF waves may be blocked or redirected by buildings and environmental features, but the waves can penetrate the structure sufficiently for the macrocell to provide services to the UE 115 located indoors. Compared to transmissions using lower frequencies and longer waves in the high frequency (HF) or very high frequency (VHF) portion of the spectrum below 300MHz, transmissions using UHF waves can be associated with smaller antennas and shorter distances (e.g., less than 100 kilometers).

[0044] The wireless communication system 100 may also operate in a super high frequency (SHF) region using a frequency band of 3 GHz to 30 GHz (also referred to as a centimeter band), or in an extremely high frequency (EHF) region (also referred to as a millimeter wave band) of the spectrum (e.g., from 30 GHz to 300 GHz). In some examples, the wireless communication system 100 may support millimeter wave (mmW) communications between UE 115 and base station 105, and the EHF antenna of the corresponding device may be even smaller and more closely spaced than the UHF antenna. In some examples, this may facilitate the use of antenna arrays within the device. However, the propagation of EHF transmissions may be subject to even greater atmospheric attenuation and shorter distances than SHF transmissions or UHF transmissions. The technology disclosed herein may be used across transmissions using one or more different frequency regions, and the designated use of frequency bands across these frequency regions may differ from country to country or regulatory party.

[0045] The wireless communication system 100 can utilize both licensed radio spectrum bands and unlicensed radio spectrum bands. For example, the wireless communication system 100 can employ license assisted access (LAA), LTE-unlicensed (LTE-U) radio access technology, or NR technology in an unlicensed band (e.g., a 5 GHz industrial, scientific, and medical (ISM) band). When operating in an unlicensed radio spectrum band, devices such as base stations 105 and UEs 115 can employ carrier sensing for conflict detection and avoidance. In some examples, operations in an unlicensed band can be based on a carrier aggregation configuration combined with component carriers operating in a licensed band (e.g., LAA). Operations in an unlicensed spectrum can include downlink transmissions, uplink transmissions, P2P transmissions, or D2D transmissions, among others.

[0046] The base station 105 or UE 115 may be equipped with multiple antennas, which may be used to employ technologies such as transmit diversity, receive diversity, multiple-input multiple-output (MIMO) communications, or beamforming. The antennas of the base station 105 or UE 115 may be located in one or more antenna arrays or antenna panels, wherein the antenna arrays or antenna panels may support MIMO operations, 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 the base station 105 may be located in different geographical locations. The base station 105 may have an antenna array having several rows and columns of antenna ports that the base station 105 may use to support beamforming of communications with the UE 115. Similarly, the UE 115 may have one or more antenna arrays that may support various MIMO or beamforming operations. Additionally or alternatively, the antenna panel may support radio frequency beamforming for signals sent via the antenna ports.

[0047] The base station 105 or UE 115 can use MIMO communication to adopt multipath signal propagation and increase spectrum efficiency by sending or receiving multiple signals via different spatial layers. Such a technology can be referred to as spatial multiplexing. For example, multiple signals can be sent by a transmitting device via different antennas or different antenna combinations. Similarly, multiple signals can be received by a receiving device via different antennas or different antenna combinations. Each of the multiple signals can be referred to as a separate spatial stream and can carry bits associated with the same data stream (e.g., the same codeword) or different data streams (e.g., different codewords). Different spatial layers can be associated with different antenna ports used for channel measurement and reporting. MIMO technology includes single-user MIMO (SU-MIMO) for sending multiple spatial layers to the same receiving device, and multi-user MIMO (MU-MIMO) for sending multiple spatial layers to multiple devices.

[0048] 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., a base station 105, a UE 115) to shape or manipulate antenna beams (e.g., a transmit beam, a receive beam) along a spatial path between the transmitting device and the receiving device. Beamforming can be achieved by combining signals transmitted via antenna elements of an antenna array so that some signals propagating in a specific orientation relative to the antenna array experience constructive interference, while other signals experience destructive interference. Adjustments to signals transmitted via antenna elements may include the transmitting device or the receiving device applying an amplitude offset, a phase offset, or both to signals carried via antenna elements associated with the device. Adjustments associated with each antenna element may be defined by a set of beamforming weights associated with a specific orientation (e.g., relative to the antenna array of the transmitting device or the receiving device or relative to some other orientation).

[0049] The base station 105 or the UE 115 may use beam scanning techniques as part of a beamforming operation. For example, the base station 105 may use multiple antennas or antenna arrays (e.g., antenna panels) to perform beamforming operations for directional communications with the UE 115. Some signals (e.g., synchronization signals, reference signals, beam selection signals, or other control signals) may be sent multiple times by the base station 105 in different directions. For example, the base station 105 may send signals based on different sets of beamforming weights associated with different transmission directions. Transmissions in different beam directions may be used (e.g., by a transmitting device such as the base station 105, or by a receiving device such as the UE 115) to identify a beam direction for later transmission or reception by the base station 105.

[0050] Some signals, such as data signals associated with a particular receiving device, may be sent by base station 105 in a single beam direction (e.g., a direction associated with a receiving device such as UE 115). In some examples, a beam direction associated with transmissions along a single beam direction may be determined based on signals sent in one or more beam directions. For example, UE 115 may receive one or more signals sent by base station 105 in different directions and may report to base station 105 an indication of the signal received by UE 115 with the highest signal quality or other acceptable signal quality.

[0051] In some examples, transmissions by a device (e.g., by a base station 105 or a UE 115) may be performed using multiple beam directions, and the device may use a combination of digital precoding or radio frequency beamforming to generate a combined beam for transmission (e.g., from the base station 105 to the UE 115). The UE 115 may report feedback indicating precoding weights for one or more beam directions, and the feedback may correspond to a configured number of beams across the system bandwidth or one or more subbands. The base station 105 may send reference signals (e.g., cell-specific reference signals (CRS), channel state information reference signals (CSI-RS)) that may or may not be precoded. The UE 115 may provide feedback for beam selection, which may be a precoding matrix indicator (PMI) or codebook-based feedback (e.g., a multi-panel type codebook, a linear combination codebook, a port selection codebook). Although these techniques are described with reference to signals sent by base station 105 in one or more directions, UE 115 may employ similar techniques for sending signals multiple times in different directions (e.g., for identifying a beam direction for subsequent transmission or reception by UE 115), or for sending signals in a single direction (e.g., for sending data to a receiving device).

[0052] A receiving device (e.g., UE 115) may try multiple reception configurations (e.g., directional detection) when receiving various signals (such as synchronization signals, reference signals, beam selection signals, or other control signals) from a base station 105. For example, the receiving device may try multiple reception directions by receiving via different antenna subarrays, processing received signals according to different antenna subarrays, receiving according to different receive beamforming weight sets (e.g., different directional detection weight sets) applied to signals received at multiple antenna elements of an antenna array, or processing received signals according to different receive beamforming weight sets applied to signals received at multiple antenna elements of an antenna array, wherein any of these operations may be referred to as "detecting" according to different reception configurations or reception directions. In some examples, a receiving device may use a single reception configuration to receive along a single beam direction (e.g., when receiving a data signal). The single reception configuration may be aligned on a beam direction determined based on detecting according to different reception configuration directions (e.g., a beam direction determined to have the highest signal strength, the highest SNR, or other acceptable signal quality based on detecting according to multiple beam directions).

[0053] The wireless communication system 100 may be a packet-based network that operates according to a layered protocol stack. In the user plane, the communication at the bearer or packet data convergence protocol (PDCP) layer may be IP-based. The radio link control (RLC) layer may perform packet segmentation and reassembly to communicate on a logical channel. The MAC layer may perform priority processing and multiplexing of logical channels to transport channels. The MAC layer may 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 may provide the establishment, configuration, and maintenance of an RRC connection that supports radio bearers for user plane data between UE 115 and base station 105 or core network 130. At the physical layer, transport channels may be mapped to physical channels.

[0054] The wireless communication system 100 may support reference signals that may enable the base station 105 or the UE 115 to estimate channel conditions or enhance reliability or efficiency of communications, etc. For example, the TRS may be implemented by the UE 115 or the base station 105 for timing tracking, frequency tracking, etc. As an illustrative example, the base station 105 may receive the TRS from the UE 115 and estimate the frequency offset at the UE 115 based on the TRS. However, in some cases, the UE 115 may experience a relatively high amount of frequency error (e.g., for higher frequency bands, such as FR2x, FR4, etc.), which may reduce the accuracy of the frequency offset estimate.

[0055] According to the techniques described herein, a UE 115 may be configured with multiple TRS configurations (e.g., multiple TRS modes according to corresponding parameter sets). For example, a base station 105 may configure multiple TRS configurations at a UE 115. The described techniques may enable a UE 115 to select from (e.g., switch between) multiple TRS configurations. In some examples, different TRS configurations may be implemented according to a digital scheme, an operating SNR, a residual error threshold, or a combination thereof, as well as other parameter examples, which may result in improved accuracy for frequency offset estimation and flexible TRS modes in the system, as well as other advantages.

[0056] For example, the base station 105 may configure the UE 115 with a set of TRS configurations (e.g., the base station 106 may send a first TRS configuration and a second TRS configuration to the UE 115). The UE 115 may identify an indicator for a selection result from the set of TRS configurations. The UE 115 may send a tracking reference signal according to a selected TRS configuration based on the identified indicator. For example, in addition to other examples of selecting a TRS configuration based on an indicator, the UE 115 may select a TRS configuration based on an identified bandwidth portion, an indicator received via control signaling, a non-periodic TRS trigger, an indicator received during a random access channel process, and an identified transmission configuration indicator state, or any combination thereof.

[0057] Figure 2 An example of a wireless communication system 200 that supports techniques for flexible reference signal modes in a wireless communication system according to aspects of the present disclosure is shown. In some examples, the wireless communication system 200 can implement aspects of the wireless communication system 100. The wireless communication system 200 can include a UE 115-a and a base station 105-a, which can be as described with reference to FIG. Figure 1 An example of a UE 115 and a base station 105 is depicted. The base station 105-a may be associated with a cell that provides wireless communication services having a coverage area 110-a. The base station 105-a may communicate with the UE 115-a using downlink communications 205 or uplink communications 210.

[0058] The wireless communication system 200 may support TRS for estimating frequency offset in the system. For example, a receiving device (e.g., a base station 105-a or a UE 115-a) may receive TRS. Although in some cases it is mentioned that a base station (e.g., base station 105) receives a reference signal (e.g., TRS), any of the techniques or aspects described herein may additionally or alternatively support a UE (e.g., UE115) receiving a reference signal (e.g., TRS) and estimating frequency offset. The receiving device may use TRS to estimate frequency offset (e.g., to track the phase of a local oscillator at a transmitter device and a receiver device). For example, the receiving device may apply a quadri-correlator (e.g., for two TRS symbols or bursts for an OFDM or single carrier (SC) waveform) to estimate frequency offset (e.g., frequency error). For example, the receiving device may apply a quadri-correlator (e.g., for two TRS symbols or bursts for an OFDM or single carrier (SC) waveform) to estimate frequency offset. For example, the receiving device may apply a quadri-correlator (e.g., for two TRS symbols or bursts for an OFDM or single carrier (SC) waveform) to estimate frequency offset (e.g., frequency error). ... TRS is sent in two bursts of 10 samples) or resource elements.

[0059] The performance of the frequency offset estimation (e.g., in terms of the variance of the estimation error) may be inversely proportional to the received SNR (e.g., a higher SNR may result in a smaller error in the frequency offset estimation), inversely proportional to the total number of TRS resource elements in each symbol or burst, inversely proportional to the square of the gap between TRS symbols or bursts used for the quad correlator, etc. In some cases, the performance of the frequency offset estimation in terms of pull in range (e.g., how large a frequency error the receiver can estimate and correct) may be inversely proportional to the gap between TRS symbols and bursts. For example, a larger gap may reduce the error in the frequency offset estimation, but may also reduce the pull in range. Accordingly, the techniques described herein may enable a network (e.g., a base station 105-a) to configure a TRS mode based on the performance of the frequency offset estimation (e.g., the base station 105-a may balance a trade-off between a mode that results in a relatively high accuracy error estimate and a lower pull in range or a lower accuracy error estimate and a higher pull in range).

[0060] The wireless communication system 200 can support multiple TRS modes (e.g., multiple TRS configurations), for example, in relatively high frequency bands. For example, UE 115-a can be configured with multiple TRS configurations. In some cases, base station 105-a can configure (e.g., via downlink communication 205) multiple TRS configurations at UE 115-a. The described technology can enable UE 115-a to select from multiple TRS configurations (e.g., switch between multiple TRS configurations). In other words, depending on the digital scheme, operating SNR, target frequency error threshold or a combination thereof, and other parameter examples, different TRS configurations can be implemented, which brings improved accuracy for frequency offset estimation, flexible TRS modes in the system (e.g., various TRS configurations can be configured and implemented based on various parameters to improve capture range or error estimation), and other advantages.

[0061] In some examples, when a synchronization signal block (SSB) uses a relatively smaller subcarrier spacing (SCS) than a corresponding channel (e.g., a control channel or a shared channel), the starting frequency error in the connected state may be lower, which may enable the UE 115-a or base station 105-a to implement a TRS mode with a lower capture range. This implementation can result in a mode with a relatively small estimation error variance (e.g., relatively accurate frequency error detection or correction). For example, the UE 115-a can use one or more techniques described herein to select a TRS configuration with a parameter set that results in a TRS mode with a lower capture range (e.g., the base station 105-a can indicate the selected TRS configuration, the UE 115-a can switch to a bandwidth portion or TCI state corresponding to the selected TRS configuration, etc.).

[0062] In some examples, the wireless communication system 200 may support demodulation reference signal (DMRS) bundling. In such an example, the base station 105-a may configure a TRS mode that brings a relatively low frequency offset estimation error. For example, the receiving device may use DMRS across multiple time slots to estimate channel conditions (e.g., the receiving device may combine DMRS across multiple time slots), which may use relatively high consistency (e.g., relatively low residual frequency offset). Such an estimate may be obtained by the base station 105-a allocating relatively more TRS resource elements for each TRS symbol or burst during a time slot in which DMRS bundling is enabled. In addition or alternatively, the base station 105-a may increase the gap between TRS symbols or bursts to reduce errors (e.g., the base station 105-b may increase the gap so that the capture range threshold is met). In some examples, the UE 115-a may be in a higher geometry or SNR operating point. In such an example, the base station 105-a may configure relatively fewer TRS resource elements, which may bring reduced system overhead and other advantages. Although the techniques described herein are discussed with reference to a TRS, it should be understood that the techniques described herein may be applicable to any reference signal.

[0063] The base station 105-a may configure the UE 115-a with at least a first TRS configuration (e.g., a first TRS mode according to a first parameter set) and a second TRS configuration (e.g., a second TRS mode according to a second parameter set). The UE 115-a may identify an indicator for a selection result from among the TRS configurations. The UE 115-a may receive TRS according to the selected TRS configuration based on the identified indicator. In some examples, the UE 115-a may select a TRS configuration based on an identified bandwidth part. For example, the first bandwidth part may correspond to a first TRS configuration and the second bandwidth part may correspond to a second TRS configuration, and the UE 115-a may select the corresponding TRS configuration based on whether the identified bandwidth part is the first bandwidth part or the second bandwidth part. In other words, the UE 115-a may send TRS using a first configuration on a first BWP and a second configuration on a second BWP. Additionally or alternatively, the base station 105-a may send an indicator for switching the TRS configuration via control signaling (e.g., via RRC configuration signaling, MAC-CE signaling, downlink control information (DCI), etc.). The UE 115-a may switch from the first TRS configuration to the second TRS configuration based on the indicator in the control signaling, which may enable the base station to update the UE 115-a with a different TRS configuration within the same bandwidth portion.

[0064] In some examples, base station 105-a may configure UE 115-a with a default TRS configuration (e.g., for periodic resources) and may send a non-periodic TRS trigger to indicate a different TRS configuration (e.g., for non-periodic resources indicated by the TRS trigger). In some examples, base station 105-a may send a message indicating the TRS configuration as part of a RACH process (e.g., message 2 or message B in a 4-step RACH process or a 2-step RACH process, respectively). In some examples, UE 115-a may select a TRS configuration based on an identified TCI state (e.g., different beams may correspond to different TCI states). For example, UE 115-a may select a TRS configuration corresponding to an identified TCI state.

[0065] In some examples, a reference signal may be sent in uplink communication 210. The reference signal may be sent along with other uplink signaling, such as data signaling, control signaling, or other reference signals. For example, base station 105-a may schedule UE 115-a for transmission via uplink communication 210, and the transmission may include a reference signal and may include other signaling. In some examples, the transmission may include other reference signals, which may also be configured according to one or more configurations. For example, the transmission may include a DMRS or a sounding reference signal (SRS), each of which may be configured according to an independent configuration. Additionally or alternatively, the reference signal may be included in downlink communication 205. For example, as described herein, a TRS may be sent via downlink communication 205 (e.g., using other downlink signaling, such as data signaling, control signaling, other reference signals, etc.).

[0066] Figure 3 An example of a resource scheme 300 supporting techniques for flexible reference signal modes in a wireless communication system in accordance with aspects of the present disclosure is shown. In some examples, the resource scheme 300 can implement aspects of the wireless communication system 100 or 200. For example, the resource scheme 300 can illustrate communications between a base station 105 and a UE 115 as described herein. In general, the resource scheme 300 can show examples of implementing different TRS configurations (e.g., TRS modes) for different bandwidth parts (BWPs) (e.g., BWP 305-a and BWP 305-b), respectively.

[0067] The UE may communicate with the base station via a BWP 305-a having a first frequency range. For example, the UE may transmit a signal (e.g., uplink data, control, or reference signal) using the time-frequency resources (e.g., resource elements) of the BWP 305-a on a first time resource set. The UE may receive TRS according to a first TRS configuration 310-a corresponding to the BWP 305-a during the first time resource set. For example, the UE may be configured (e.g., by the base station) such that the first BWP 305-a is associated with (e.g., tied to) the first TRS configuration 310-a and the second BWP 305-b is associated with the second TRS configuration 310-b. The UE may identify the BWP 305-a for transmitting the first TRS, and may select the first TRS configuration 310-a based on a configured correspondence between the BWP 305-a and the first TRS configuration 310-a. Thus, for example, different TRS modes may be configured depending on the digital scheme configured for a given BWP 305. In some examples, a TRS configuration 310 that results in a relatively lower error for frequency offset estimation may be configured with a BWP 305 that utilizes a relatively higher frequency band, etc.

[0068] The first TRS configuration 310-a may include a first set of parameters for sending TRS via BWP 305-a. For example, the first set of parameters may include a TRS burst length of a certain number of time slots, a TRS burst period of a certain number of time slots, an amount of symbols for TRS within a time slot, a TRS bandwidth (e.g., the first set of parameters may indicate BWP 305-a), a TRS subcarrier spacing, or a TRS symbol spacing within a time slot, and other parameter examples. The second TRS configuration 310-b may include a second set of parameters for sending TRS via BWP305-b. For example, the second set of parameters may include a TRS burst length of a certain number of time slots, a TRS burst period of a certain number of time slots, an amount of symbols for TRS within a time slot, a TRS bandwidth (e.g., the second set of parameters may indicate BWP 305-b), a TRS subcarrier spacing, or a TRS symbol spacing within a time slot, and other parameter examples.

[0069] The UE may identify a second BWP 305-b having a second frequency range. For example, for a second set of time resources, the UE may switch from BWP 305-a to BWP 305-b. In some cases, the UE may switch BWP 305 based on receiving a DCI from the base station indicating that the UE will switch to BWP 305-b for communication. Additionally or alternatively, the UE may be configured with a timer. The UE may switch to BWP 305-b based on expiration of the timer.

[0070] The UE may select a second TRS configuration 310-b from a set of TRS configurations 310 based on the identified BWP 305-b. For example, the BWP 305-b may be associated with the second TRS configuration 310-b (e.g., the BWP configuration for the BWP 305-b may correspond to or be associated with the TRS configuration 310-b). In some cases, the UE may identify an indicator for selecting the TRS configuration 310-b, wherein the indicator includes the identified BWP 305-b (e.g., the BWP configuration for the BWP 305-b). The UE may receive TRS according to the second TRS configuration 310-b (e.g., using a second TRS mode based on a second set of parameters). In some cases, such techniques may enable the UE to automatically apply a different TRS mode when switching from the first BWP 305 to the second BWP 305.

[0071] Figure 4 An example of a resource scheme 400 supporting techniques for flexible reference signal modes in a wireless communication system in accordance with aspects of the present disclosure is shown. In some examples, the resource scheme 400 can implement aspects of the wireless communication system 100 or 200. For example, the resource scheme 400 can illustrate communications between a base station 105 and a UE 115 as described herein. In general, the resource scheme 400 can show examples of implementing different TRS configurations (e.g., different TRS modes for the same BWP (e.g., BWP 405)) based on control signaling from a base station.

[0072] The UE may communicate with the base station via the BWP 405. For example, the UE may use the time-frequency resources (e.g., resource elements) of the BWP 405 to send and receive signals (e.g., data signals, control signals, reference signals). The UE may receive TRS according to the first TRS configuration 410-a during the first set of time resources. In some examples, the base station may send control signaling including an indicator for a selection result from among multiple TRS configurations to the UE. For example, the base station may configure the UE to use the first TRS configuration 410-a for the first set of time resources via RRC signaling (e.g., RRC configuration for the first TRS configuration 410-a), MAC-CE signaling (e.g., a field in the MAC-CE may indicate the first TRS configuration 410-a), DCI, or any combination thereof. In some examples, such control signaling may additionally or alternatively configure the UE with a set of multiple TRS configurations (e.g., the base station may send the first TRS configuration and the second TRS configuration to the UE before sending an indicator for the selection result of one or both of the first TRS configuration and the second TRS configuration). As an illustrative example, the UE may transmit a first TRS at a first time via the BWP 405 using the first TRS configuration 410-a. The first TRS configuration 410-a may include a first set of parameters for sending the TRS via the BWP 405. For example, the first set of parameters may include a TRS burst length of a certain number of time slots, a TRS burst period of a certain number of time slots, an amount of symbols for the TRS within a time slot, a TRS bandwidth (e.g., the first set of parameters may indicate the BWP 405), a TRS subcarrier spacing, or a TRS symbol spacing within a time slot, as well as other parameter examples.

[0073] The UE may receive control signaling including an indicator for a selection result among a set of TRS configurations 410 after receiving the first TRS and before receiving the second TRS. For example, the UE may receive control signaling indicating a second TRS configuration 410-b for a second set of time resources. The second TRS configuration 410-b may include a second set of parameters for sending the TRS via the BWP 405. For example, the second set of parameters may include a TRS burst length of a certain number of time slots, a TRS burst period of a certain number of time slots, a symbol amount for the TRS within a time slot, a TRS bandwidth (e.g., the second set of parameters may indicate the BWP 405), a TRS subcarrier spacing, or a TRS symbol spacing within a time slot, and other parameter examples. The UE may receive a second TRS according to the second TRS configuration 410-b based on identifying an indicator for a selection result indicating the second TRS configuration 410-b (e.g., according to the control signaling). Such techniques may enable a base station to update a UE with a TRS pattern for the same BWP 405, which may enhance flexibility in the communication system, as well as achieve other advantages.

[0074] Figure 5 An example of a resource scheme 500 supporting techniques for flexible reference signal modes in a wireless communication system in accordance with aspects of the present disclosure is shown. In some examples, the resource scheme 500 can implement aspects of the wireless communication system 100 or 200. For example, the resource scheme 500 can illustrate communications between a base station 105 and a UE 115 as described herein. In general, the resource scheme 500 can illustrate examples for implementing different TRS configurations for periodic communications and / or aperiodic communications.

[0075] The UE may communicate with the base station via resources 505. For example, the UE may receive a TRS at a first time using time-frequency resources (e.g., resource elements) of resources 505-a, which may be examples of a BWP as described herein. In some examples, the base station may configure the UE with a set of TRS configurations 510. For example, the base station may send (e.g., via control signaling) a first TRS configuration 510-a and a second TRS configuration 510-b, although any number of TRS configurations at the UE may be configured.

[0076] The UE may receive a first TRS according to a first TRS configuration 510-a. In some examples, the UE may identify an indicator for a selection result among a set of TRS configurations 510-a. For example, the UE may be scheduled with periodic resources 505-a and 505-c. The UE may identify an identifier based on identifying periodic resources 505-a and 505-c. For example, the UE may use a first TRS configuration 510-a (e.g., a periodic TRS configuration 510) based on the identified periodic resources 505-a and 505-c. In other words, the UE may apply a first TRS configuration 510-a (e.g., generating a first parameter set for a first TRS mode) to the periodic resources 505, wherein the indicator for the selection result includes an indication of the periodic resources 505-a and 505-c. The base station may (e.g., dynamically) trigger an aperiodic TRS configuration 510-b. For example, the base station may send a non-periodic message indicating non-periodic resources 505-b to the UE (e.g., for relatively high priority communications, and other scheduling examples). In some examples, the base station may send the non-periodic message via DCI, RRC signaling, etc. The UE may receive a message including an indicator for the selection result in various TRS configurations 510. For example, the UE may receive TRS according to the second TRS configuration 510-b based on the non-periodic message indicating the second TRS configuration 510-b. In some examples, such a triggering by the network for applying the non-periodic TRS mode may depend on a target threshold (e.g., in addition to the periodically scheduled TRS transmission via the periodic resources 505 using different TRS modes, the base station may determine the time slot or a certain number of time slots for the non-periodic TRS transmission using the TRS mode with improved error estimation capability). In some examples, the non-periodic TRS trigger 515 (e.g., an indicator included in the non-periodic message) may not change the underlying periodic TRS configuration 510-a. In some other examples, the non-periodic TRS trigger 515 may also change subsequent periodic resources 505 to send TRS according to a second TRS configuration 510-b (eg, using a second set of parameters for a second TRS mode).

[0077] Figure 6 An example of a process flow 600 is shown for supporting techniques for flexible reference signal modes in a wireless communication system in accordance with aspects of the present disclosure. In some examples, the process flow 600 can implement aspects of the wireless communication system 100 or 200. For example, the process flow 600 can illustrate communications between a base station 105-b and a UE 115-b, which can be examples of corresponding devices described herein. In general, the process flow 600 can illustrate an example of implementing a TRS mode as part of a RACH procedure.

[0078] The following alternative examples may be implemented in which some of the processes are either performed in a different order than described or not performed at all. In some implementations, the process may include additional features not mentioned below, or further processes may be added.

[0079] At 605, UE 115-b may send a first message to base station 105-b. The first message may be an example of an initial message of a RACH procedure. For example, the first message may be referred to as msg1 in a 4-step RACH procedure, or msgA in a 2-step RACH procedure, among other examples. The first message may include a preamble with information associated with UE 115-b.

[0080] At 610, the base station 105-b may send a second message to the UE 115-b in response to receiving the first message. The second message may be a second message in a RACH process. For example, the second message may be referred to as msg2 in a 4-step RACH process, or msgB in a 2-step RACH process, among other examples. The second message may include an indicator for a selection result in one or more TRS configurations. For example, the base station 105-b may select a TRS configuration (e.g., a TRS configuration including a corresponding set of parameters) to trigger for the UE 115-b or a set of UEs 115. The base station 105-b may select a TRS configuration based on one or more parameters as described herein (e.g., the base station 105-b may select a TRS mode based on other examples of parameters such as a high frequency band and parameters such as SNR measurements, residual error thresholds, digital schemes, etc., to improve frequency error estimation accuracy).

[0081] The base station 105-b may trigger the selected TRS configuration via a second message. For example, the second message may include an indicator of a selection result in a set of TRS configurations configured at the UE 115-b, for example via remaining minimum system information (RMSI). At 615, the UE 115-b may receive the second message and select a TRS configuration based on identifying the indicator included in the second message. In some cases, the TRS configuration (e.g., a TRS mode indicated by a set of parameters for the TRS configuration) or a trigger for applying the TRS configuration may be sent on a DCI of the second message or in a physical downlink shared channel (PDSCH) payload of the second message. In some examples, the base station 105-b may select a trigger for a TRS mode selected for a detected corresponding preamble or a detected UE 115 (e.g., the base station 105-a may select a TRS mode for the UE 115-b and indicate the TRS mode). For example, base station 105-b may detect a frequency error for a given preamble (e.g., a given UE 115), and base station 105-b may select a different TRS mode to trigger or prohibit triggering a different TRS mode based on the detected frequency error. In some examples, base station 105-b may trigger a TRS configuration via a DCI of the second message. In some such examples, base station 105-b may select to trigger the same TRS configuration for multiple preambles (e.g., UE 115) listed in the second message.

[0082] In some examples, at 620, UE 115-b may send a third message to base station 105-b in response to receiving the second message. Additionally or alternatively, UE 115-b may receive communications including TRS according to the selected TRS configuration (e.g., during the fourth message at 625 or during a different communication). In some cases, the third message may be a message of a RACH procedure (e.g., msg3 in a 4-step RACH procedure). In some examples, at 625, base station 105-b may send a fourth message, e.g., msg4 in a 4-step RACH procedure.

[0083] Figure 7 An example of a resource scheme 700 supporting techniques for flexible reference signal modes in a wireless communication system in accordance with aspects of the present disclosure is shown. In some examples, the resource scheme 700 can implement aspects of the wireless communication system 100 or 200. For example, the resource scheme 700 can illustrate communications between a base station 105 and a UE 115 as described herein. In general, the resource scheme 700 can illustrate examples of implementing different TRS configurations 710 for different TCI states (e.g., for different beams 715).

[0084] The UE may use different beams 715 to communicate with the base station. For example, the UE may send or receive communications via beam 715-a or beam 715-b. In some examples, the beams 715 may each be associated with a corresponding TCI state. For example, some TCI states may correspond to wider beams (e.g., having lower beamforming gain), while other TCI states may correspond to narrower beams (e.g., having better beamforming gain). According to the techniques described herein, each TCI state may correspond to a corresponding TRS configuration 710. For example, different TRS modes may be tied to different TCI states (e.g., the TCI state for beam 715-a may correspond to a first TRS configuration 710-a, and the TCI state for beam 715-b may correspond to a second TRS configuration 710-b).

[0085] In some examples, the base station may configure a TRS configuration 710 as described herein. For example, the base station may configure a first TRS configuration 710-a for a TRS transmitted via a beam 715-a that is quasi-co-located with an SSB 705-a. The base station may additionally or alternatively configure a second TRS configuration 710-b for a TRS transmitted via a beam 715-b that is quasi-co-located with an SSB 705-b. In other words, the TRS transmitted via beam 715-a may be transmitted according to a different mode than the TRS transmitted via beam 715-b.

[0086] Figure 8 An example of a process flow 800 is shown for supporting techniques for flexible reference signal modes in a wireless communication system in accordance with aspects of the present disclosure. In some examples, the process flow 800 can implement aspects of the wireless communication system 100 or 200. For example, the process flow 800 can illustrate communications between a base station 105-c and a UE 115-c, which can be examples of corresponding devices described herein. The following alternative examples can be implemented in which some processes are performed in a different order than described or not performed at all. In some implementations, the processing can include additional features not mentioned below, or further processing can be added.

[0087] At 805, the base station 105-c may send a configuration message to the UE 115-c. For example, the base station 105-c may use the configuration message to configure the UE 115-c with the TRS configuration set, the base station 105c may include an indicator for selecting a TRS configuration from the TRS configuration set, or both.

[0088] In some examples, at 810-a, UE 115-c may identify an indicator for a selection result from a set of TRS configurations. For example, UE 115-c may be configured with a TRS configuration as described herein (e.g., UE 115-c may be configured with a TRS configuration configured via a second message in a RACH process, UE 115-c may be configured with a default periodic TRS configuration, control signaling may indicate a TRS configuration, etc.). In some examples, identifying the indicator may include identifying a BWP or receiving control signaling, and referring to Figure 1-7 Other examples described.

[0089] In some examples, at 810-b, the base station 105-c may additionally or alternatively identify an indicator. Although shown as occurring after sending the configuration message 805, in some examples, the base station 105-c may identify an indicator for a selection result from among the TRS configurations before sending the configuration message (e.g., if the configuration message includes the indicator).

[0090] At 815, UE 115-c may receive a TRS from base station 105-c. For example, based on a TRS configuration, base station 105-c may send a TRS and UE 115-c may receive the TRS. For example, a TRS transmission may be sent with a TRS mode based on a set of parameters included in the TRS configuration. In some examples, the TRS configuration is selected based on an identified indicator, a configuration message, or both.

[0091] In some examples, the UE 115-c and / or the base station 105-c may determine to switch TRS configurations. For example, the base station 105-c may determine to use a different TRS mode based on previously received TRS transmissions, the UE 115-c may switch BWPs as described herein, and so on.

[0092] In some examples, at 820, the base station 105-c may send control signaling including an indicator of a second TRS configuration for sending a subsequent TRS. The control signaling may be an example of RRC signaling, MAC-CE signaling, or DCI signaling, among other examples.

[0093] In some examples, at 825-a, UE 115-c may identify a second indicator for a selection result from among the TRS configurations. For example, UE 115-c may determine to switch to a second TRS configuration for subsequent TRS transmission based on control signaling from base station 105-c, a switch of a BWP or TCI state, etc. Additionally or alternatively, at 825-b, base station 105-c may identify a second indicator.

[0094] At 830, the UE 115-c may receive a second TRS transmission from the base station 105-c. The UE 115-c may receive the second TRS transmission according to a second TRS configuration (e.g., a second TRS mode) selected based on the identified second indicator, which may be a second TRS mode as described herein with reference to Figures 1 to 7 Examples of indicators described.

[0095] Fig. 9 A block diagram 900 of a device 905 supporting techniques for flexible reference signal modes in a wireless communication system according to aspects of the present disclosure is shown. The device 905 may be an example of aspects of a UE 115 as described herein. The device 905 may include a receiver 910, a communication manager 915, and a transmitter 920. The device 905 may also include a processor. Each of these components may communicate with each other (e.g., via one or more buses).

[0096] The receiver 910 may receive information such as packets, user data, or control information associated with various information channels (e.g., control channel information, data channel information, and information related to techniques for flexible reference signal patterns in wireless communication systems, etc.). The information may be delivered to other components of the device 905. The receiver 910 may be a reference signal. Fig.12 Examples of various aspects of the transceiver 1220 are described. The receiver 910 may utilize a single antenna or a group of antennas.

[0097] The communication manager 915 may receive a first tracking reference signal configuration and a second tracking reference signal configuration from a base station, the first tracking reference signal configuration including a first parameter set and the second tracking reference signal configuration including a second parameter set, and receive a tracking reference signal from the base station according to the first tracking reference signal configuration or the second tracking reference signal configuration based on an indicator for a selection result from among the first tracking reference signal configuration and the second tracking reference signal configuration. The communication manager 915 may also send a first message in a random access channel process to the base station, receive a second message in a random access channel process from the base station in response to sending the first message, the second message including an indicator for triggering tracking reference signal transmission, and receive a tracking reference signal from the base station according to the tracking reference signal configuration indicated by the indicator of the second message. The communication manager 915 may be an example of various aspects of the communication manager 1210 described herein.

[0098] The communication manager 915 or its subcomponents may be implemented in hardware, in code (e.g., software or firmware) executed by a processor, or any combination thereof. If implemented in code executed by a processor, the functions of the communication manager 915 or its subcomponents may be performed by a general purpose 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 designed to perform the functions described in the present disclosure.

[0099] The communication manager 915 or its subcomponents may be physically located in various locations, including being distributed so that various parts of the functionality are implemented by one or more physical devices at different physical locations. In some examples, according to various aspects of the present disclosure, the communication manager 915 or its subcomponents may be separate and distinct components. In some examples, according to various aspects of the present disclosure, the communication manager 915 or its subcomponents may be combined with one or more other hardware components, including but not limited to input / output (I / O) components, transceivers, network servers, another computing device, one or more other components described in the present disclosure, or combinations thereof.

[0100] The communication manager 915 may be implemented to achieve one or more potential advantages. Some implementations may allow the device 905 to implement flexible TRS configurations (e.g., different TRS modes). Based on implementing different TRS configurations as described herein, the system may achieve benefits such as improved accuracy or reduced processing overhead for frequency offset estimation.

[0101] The transmitter 920 can transmit signals generated by other components of the device 905. In some examples, the transmitter 920 can be collocated with the receiver 910 in the transceiver module. For example, the transmitter 920 can be a reference Fig.12 Examples of various aspects of the transceiver 1220 are described. The transmitter 920 may utilize a single antenna or a group of antennas.

[0102] Fig.10 A block diagram 1000 of a device 1005 supporting techniques for flexible reference signal modes in a wireless communication system according to aspects of the present disclosure is shown. The device 1005 may be an example of aspects of the device 905 or UE 115 as described herein. The device 1005 may include a receiver 1010, a communication manager 1015, and a transmitter 1050. The device 1005 may also include a processor. Each of these components may communicate with each other (e.g., via one or more buses).

[0103] The receiver 1010 may receive information such as packets, user data, or control information associated with various information channels (e.g., control channel information, data channel information, and information related to techniques for flexible reference signal patterns in wireless communication systems, etc.). The information may be delivered to other components of the device 1005. The receiver 1010 may be a reference signal. Fig.12 Examples of various aspects of the transceiver 1220 are described. The receiver 1010 may utilize a single antenna or a group of antennas.

[0104] The communication manager 1015 may be an example of aspects of the communication manager 915 as described herein. The communication manager 1015 may include a configuration receiver 1020, a TRS receiver 1030, a first message component 1035, a second message component 1040, and a TRS component 1045. The communication manager 1015 may be an example of aspects of the communication manager 1210 described herein.

[0105] The configuration receiver 1020 may receive a first tracking reference signal configuration and a second tracking reference signal configuration from a base station, the first tracking reference signal configuration including a first parameter set, and the second tracking reference signal configuration including a second parameter set.

[0106] The TRS receiver 1030 may receive a tracking reference signal according to the first tracking reference signal configuration or the second tracking reference signal configuration from the base station and based on an indicator of a selection result from among the first tracking reference signal configuration and the second tracking reference signal configuration.

[0107] The first message component 1035 can send a first message in a random access channel process to the base station.

[0108] The second message component 1040 can receive a second message in a random access channel process from the base station in response to sending the first message, the second message including an indicator for triggering transmission of a tracking reference signal.

[0109] The TRS component 1045 can receive a tracking reference signal from the base station according to the tracking reference signal configuration indicated by the indicator of the second message.

[0110] The transmitter 1050 can transmit signals generated by other components of the device 1005. In some examples, the transmitter 1050 can be collocated with the receiver 1010 in the transceiver module. For example, the transmitter 1050 can be a reference Fig.12 Examples of various aspects of the transceiver 1220 are described. The transmitter 1050 may utilize a single antenna or a group of antennas.

[0111] Fig.11A block diagram 1100 of a communication manager 1105 supporting techniques for flexible reference signal modes in a wireless communication system in accordance with aspects of the present disclosure is shown. The communication manager 1105 may be an example of aspects of the communication manager 915, the communication manager 1015, or the communication manager 1210 described herein. The communication manager 1105 may include a configuration receiver 1110, a TRS receiver 1120, a BWP component 1125, a configuration selection component 1130, a DCI component 1135, a timer component 1140, a control signal component 1145, an aperiodic message component 1150, a TCI component 1155, a first message component 1160, a second message component 1165, and a TRS component 1170. Each of these modules may communicate with each other directly or indirectly (e.g., via one or more buses).

[0112] Configuration receiver 1110 may receive a first tracking reference signal configuration and a second tracking reference signal configuration from a base station, the first tracking reference signal configuration including a first parameter set and the second tracking reference signal configuration including a second parameter set. In some cases, the first parameter set, the second parameter set, or both include a tracking reference signal burst length for a certain number of time slots, a tracking reference signal burst period for a certain number of time slots, a number of symbols for a tracking reference signal within a time slot, a tracking reference signal bandwidth, a tracking reference signal subcarrier spacing, or a tracking reference signal symbol spacing within a time slot.

[0113] The TRS receiver 1120 may receive a tracking reference signal according to the first tracking reference signal configuration or the second tracking reference signal configuration from the base station and based on an indicator of a selection result from among the first tracking reference signal configuration and the second tracking reference signal configuration.

[0114] The TRS component 1170 can receive a tracking reference signal according to a tracking reference signal configuration indicated by an indicator of the second message. In some cases, the indicator indicates a selected tracking reference signal configuration.

[0115] The BWP component 1125 can identify a first bandwidth portion for communication with the base station on a first set of time resources, the first bandwidth portion being associated with a first tracking reference signal configuration, wherein the indicator includes the first bandwidth portion. In some examples, the BWP component 1125 can identify a second bandwidth portion for communication with the base station on a second set of time resources, the second bandwidth portion being associated with a second tracking reference signal configuration, wherein the indicator includes the second bandwidth portion.

[0116] Configuration selection component 1130 can select a first tracking reference signal configuration for a first set of time resources based on identifying the first bandwidth portion. In some examples, configuration selection component 1130 can select a second tracking reference signal configuration for a second set of time resources based on identifying the second bandwidth portion. In some examples, configuration selection component 1130 can select the first tracking reference signal configuration based on receiving control signaling.

[0117] In some examples, configuration selection component 1130 can select a second tracking reference signal configuration for a second tracking reference signal based on receiving the second control signaling.In some examples, TRS receiver 1120 can receive the tracking reference signal and the second tracking reference signal on the same bandwidth portion.

[0118] In some examples, configuration selection component 1130 can select a second tracking reference signal configuration based on identifying the indicator as a non-periodic tracking reference signal trigger, the second tracking reference signal configuration being different from a first tracking reference signal configuration associated with periodic transmission of a tracking reference signal.

[0119] The DCI component 1135 can receive downlink control information from the base station including an indication of the second bandwidth portion.

[0120] The timer component 1140 can determine that a timer associated with the first bandwidth portion has expired, wherein switching from the first bandwidth portion to the second bandwidth portion is based on the determination.

[0121] The control signal component 1145 may receive control signaling including an indicator for the selection result from the base station. In some examples, the control signal component 1145 may receive second control signaling including a second indicator for the selection result from the first tracking reference signal configuration and the second tracking reference signal configuration from the base station. In some cases, the control signaling includes an RRC signal, a MAC-CE, or a DCI.

[0122] The aperiodic message component 1150 can receive a message including an aperiodic tracking reference signal trigger from a base station, wherein the indicator includes the aperiodic tracking reference signal trigger.

[0123] The TCI component 1155 can identify that the indicator is associated with a first transmission configuration indicator state, the first transmission configuration indicator state corresponding to a first tracking reference signal configuration. In some examples, the TRS receiver 1120 can receive a tracking reference signal from a base station and based on the identified indicator, based on the indicator as the first transmission configuration indicator state, according to the first tracking reference signal configuration. In some cases, the first synchronization signal block is quasi-co-located with the first transmission configuration indicator state and the second synchronization signal block is quasi-co-located with the second transmission configuration indicator state, and wherein the indicator includes a characteristic associated with the first synchronization signal module or the second synchronization signal module.

[0124] The first message component 1160 can send a first message in a random access channel process to the base station.

[0125] The second message component 1165 can receive a second message in a random access channel process from the base station in response to sending the first message, the second message including an indicator for triggering transmission of a tracking reference signal.

[0126] Fig.12 A diagram of a system 1200 including a device 1205 supporting techniques for flexible reference signal modes in a wireless communication system according to aspects of the present disclosure is shown. The device 1205 may be an example of or include components of a device 905, a device 1005, or a UE 115 as described herein. The device 1205 may include components for two-way voice and data communications, including components for sending and receiving communications, including a communication manager 1210, an I / O controller 1215, a transceiver 1220, an antenna 1225, a memory 1230, and a processor 1240. These components may communicate electronically via one or more buses (e.g., a bus 1245).

[0127] The communication manager 1210 may receive a first tracking reference signal configuration and a second tracking reference signal configuration from a base station, the first tracking reference signal configuration including a first parameter set and the second tracking reference signal configuration including a second parameter set, and receive a tracking reference signal from the base station according to the first tracking reference signal configuration or the second tracking reference signal configuration based on an indicator for a selection result from among the first tracking reference signal configuration and the second tracking reference signal configuration. The communication manager 1210 may also send a first message in a random access channel process to the base station, receive a second message in a random access channel process from the base station in response to sending the first message, the second message including an indicator for triggering tracking reference signal transmission, and receive a tracking reference signal from the base station according to the tracking reference signal configuration indicated by the indicator of the second message.

[0128] I / O controller 1215 can manage input and output signals for device 1205. I / O controller 1215 can also manage peripheral devices that are not integrated into device 1205. In some cases, I / O controller 1215 can represent a physical connection or port to an external peripheral device. In some cases, I / O controller 1215 can utilize a computer such as a Or other known operating systems. In other cases, I / O controller 1215 can represent or interact with a modem, keyboard, mouse, touch screen, or similar device. In some cases, I / O controller 1215 can be implemented as part of a processor. In some cases, a user can interact with device 1205 via I / O controller 1215 or via hardware components controlled by I / O controller 1215.

[0129] As described above, the transceiver 1220 can communicate bidirectionally via one or more antennas, wired or wireless links. For example, the transceiver 1220 can represent a wireless transceiver and can communicate bidirectionally with another wireless transceiver. The transceiver 1220 may also include a modem for modulating packets and providing the modulated packets to an antenna for transmission, and for demodulating packets received from an antenna.

[0130] In some cases, a wireless device may include a single antenna 1225. However, in some cases, a device may have more than one antenna 1225, which may be capable of transmitting or receiving multiple wireless transmissions simultaneously.

[0131] Memory 1230 may include random access memory (RAM) and read-only memory (ROM). Memory 1230 may store computer-readable computer executable code 1235, which includes instructions that, when executed, cause the processor to perform various functions described herein. In some cases, memory 1230 may also contain a basic input / output system (BIOS), which may control basic hardware or software operations, such as interaction with peripheral components or devices.

[0132] Processor 1240 may include an intelligent hardware device (e.g., a general purpose processor, a DSP, a CPU, a microcontroller, an ASIC, an FPGA, a programmable logic device, a discrete gate or transistor logic component, a discrete hardware component, or any combination thereof). In some cases, processor 1240 may be configured to operate a memory array using a memory controller. In other cases, the memory controller may be integrated into processor 1240. Processor 1240 may be configured to execute computer-readable instructions stored in a memory (e.g., memory 1230) to cause device 1205 to perform various functions (e.g., functions or tasks for supporting techniques for flexible reference signal modes in wireless communication systems).

[0133] The code 1235 may include instructions to implement various aspects of the present disclosure, including instructions to support wireless communications. The code 1235 may be stored in a non-transitory computer-readable medium such as a system memory or other type of memory. In some cases, the code 1235 may not be directly executable by the processor 1240, but may cause a computer (e.g., when compiled and executed) to perform the functions described herein.

[0134] Fig.13 A block diagram 1300 of a device 1305 supporting techniques for flexible reference signal modes in a wireless communication system in accordance with aspects of the present disclosure is shown. The device 1305 may be an example of aspects of a base station 105 as described herein. The device 1305 may include a receiver 1310, a communication manager 1315, and a transmitter 1320. The device 1305 may also include a processor. Each of these components may communicate with each other (e.g., via one or more buses).

[0135] The receiver 1310 may receive information such as packets, user data, or control information associated with various information channels (e.g., control channel information, data channel information, and information related to techniques for flexible reference signal patterns in wireless communication systems, etc.). The information may be delivered to other components of the device 1305. The receiver 1310 may be a reference signal. Fig.16 Examples of various aspects of the transceiver 1620 are described. The receiver 1310 may utilize a single antenna or a group of antennas.

[0136] The communication manager 1315 may send a first tracking reference signal configuration and a second tracking reference signal configuration to one or more UEs, the first tracking reference signal configuration including a first parameter set and the second tracking reference signal configuration including a second parameter set, and send a tracking reference signal to the one or more UEs and based on an indicator for a selection result from the first tracking reference signal configuration and the second tracking reference signal configuration according to the first tracking reference signal configuration or the second tracking reference signal configuration. The communication manager 1315 may also receive a first message in a random access channel process from the one or more UEs, send a second message in a random access channel process to the one or more UEs in response to sending the first message, the second message including an indicator for triggering tracking reference signal transmission, and send a tracking reference signal to the one or more UEs according to the tracking reference signal configuration indicated by the indicator of the second message. The communication manager 1315 may be an example of various aspects of the communication manager 1610 described herein.

[0137] The communication manager 1315 or its subcomponents may be implemented in hardware, in code (e.g., software or firmware) executed by a processor, or any combination thereof. If implemented in code executed by a processor, the functions of the communication manager 1315 or its subcomponents may be performed by a general purpose processor, a DSP, an application specific integrated circuit (ASIC), an FPGA or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described in this disclosure.

[0138] The communication manager 1315 or its subcomponents can be physically located in various locations, including being distributed so that various parts of the functions are implemented by one or more physical devices at different physical locations. In some examples, according to various aspects of the present disclosure, the communication manager 1315 or its subcomponents can be separate and different components. In some examples, according to various aspects of the present disclosure, the communication manager 1315 or its subcomponents can be combined with one or more other hardware components, including but not limited to input / output (I / O) components, transceivers, network servers, another computing device, one or more other components described in the present disclosure, or combinations thereof.

[0139] The transmitter 1320 may transmit signals generated by other components of the device 1305. In some examples, the transmitter 1320 may be collocated with the receiver 1310 in the transceiver module. For example, the transmitter 1320 may be a reference Fig.16 Examples of various aspects of the transceiver 1620 are described. The transmitter 1320 may utilize a single antenna or a group of antennas.

[0140] Fig.14 A block diagram 1400 of a device 1405 supporting techniques for flexible reference signal modes in a wireless communication system according to aspects of the present disclosure is shown. The device 1405 may be an example of aspects of the device 1305 or base station 105 described herein. The device 1405 may include a receiver 1410, a communication manager 1415, and a transmitter 1450. The device 1405 may also include a processor. Each of these components may communicate with each other (e.g., via one or more buses).

[0141] Receiver 1410 may receive information such as packets, user data, or control information associated with various information channels (e.g., control channel information, data channel information, and information related to techniques for flexible reference signal patterns in wireless communication systems, etc.). The information may be delivered to other components of device 1405. Receiver 1410 may be a reference signal. Fig.16 Examples of various aspects of the transceiver 1620 are described. The receiver 1410 may utilize a single antenna or a group of antennas.

[0142] The communication manager 1415 may be an example of aspects of the communication manager 1315 described herein. The communication manager 1415 may include a configuration transmitter 1420, a TRS transmitter 1430, a first message module 1435, a second message module 1440, and a TRS module 1445. The communication manager 1415 may be an example of aspects of the communication manager 1610 described herein.

[0143] Configuration transmitter 1420 may send a first tracking reference signal configuration and a second tracking reference signal configuration to one or more UEs, the first tracking reference signal configuration including a first set of parameters and the second tracking reference signal configuration including a second set of parameters.

[0144] The TRS transmitter 1430 may transmit a tracking reference signal according to the first tracking reference signal configuration or the second tracking reference signal configuration to one or more UEs and based on an indicator of a selection result from among the first tracking reference signal configuration and the second tracking reference signal configuration.

[0145] The first message module 1435 may receive a first message in a random access channel procedure from one or more UEs.

[0146] The second message module 1440 may send a second message in a random access channel process to one or more UEs in response to sending the first message, where the second message includes an indicator for triggering transmission of a tracking reference signal.

[0147] The TRS module 1445 may send a tracking reference signal to one or more UEs according to the tracking reference signal configuration indicated by the indicator of the second message.

[0148] The transmitter 1450 may transmit signals generated by other components of the device 1405. In some examples, the transmitter 1450 may be collocated with the receiver 1410 in the transceiver module. For example, the transmitter 1450 may be a reference Fig.16 Examples of various aspects of the transceiver 1620 are described. The transmitter 1450 may utilize a single antenna or a group of antennas.

[0149] Fig.15A block diagram 1500 of a communication manager 1505 supporting techniques for flexible reference signal modes in a wireless communication system in accordance with aspects of the present disclosure is shown. The communication manager 1505 may be an example of aspects of the communication manager 1315, the communication manager 1415, or the communication manager 1610 described herein. The communication manager 1505 may include a configuration transmitter 1510, a TRS transmitter 1520, a BWP module 1525, a configuration selection module 1530, a DCI module 1535, a timer module 1540, a control signal module 1545, an aperiodic message module 1550, a TCI module 1555, a first message module 1560, a second message module 1565, a TRS module 1570, and a trigger module 1575. Each of these modules may communicate with each other directly or indirectly (e.g., via one or more buses).

[0150] Configuration transmitter 1510 may send a first tracking reference signal configuration and a second tracking reference signal configuration to one or more UEs, the first tracking reference signal configuration including a first parameter set and the second tracking reference signal configuration including a second parameter set. In some cases, the first parameter set, the second parameter set, or both include a tracking reference signal burst length for a certain number of time slots, a tracking reference signal burst period for a certain number of time slots, a number of symbols for a tracking reference signal within a time slot, a tracking reference signal bandwidth, a tracking reference signal subcarrier spacing, or a tracking reference signal symbol spacing within a time slot.

[0151] TRS transmitter 1520 may transmit a tracking reference signal according to a first tracking reference signal configuration or a second tracking reference signal configuration to one or more UEs and based on an indicator for a selection result from among the first tracking reference signal configuration and the second tracking reference signal configuration. In some examples, TRS transmitter 1520 may transmit a tracking reference signal and a second tracking reference signal according to a same bandwidth portion configuration. In some examples, TRS transmitter 1520 may transmit a tracking reference signal according to a first tracking reference signal configuration based on an indicator, based on identifying the indicator as a first transmission configuration indicator.

[0152] The TRS module 1570 may transmit a tracking reference signal according to the tracking reference signal configuration indicated by the indicator of the second message.

[0153] The BWP module 1525 may identify a first bandwidth portion for receiving a tracking reference signal, the first bandwidth portion being associated with a first tracking reference signal configuration, wherein the indicator includes the first bandwidth portion. In some examples, the BWP module 1525 may identify a second bandwidth portion for transmitting a tracking reference signal, the second bandwidth portion being associated with a second tracking reference signal configuration, wherein the indicator includes the second bandwidth portion. In some examples, the BWP module 1525 may switch from the first bandwidth portion to the second bandwidth portion based on identifying the second bandwidth portion.

[0154] Configuration selection module 1530 may select the first tracking reference signal configuration based on identifying the first bandwidth portion. In some examples, configuration selection module 1530 may select the second tracking reference signal configuration based on switching from the first bandwidth portion to the second bandwidth portion. In some examples, configuration selection module 1530 may select the first tracking reference signal configuration based on sending control signaling.

[0155] In some examples, configuration selection module 1530 can select a second tracking reference signal configuration for the second tracking reference signal based on sending the second control signaling. In some examples, configuration selection module 1530 can select a second tracking reference signal configuration based on sending the message, the second tracking reference signal configuration being different from a first tracking reference signal configuration associated with the periodic transmission of the tracking reference signal.

[0156] The DCI module 1535 may send downlink control information including an indication of the second bandwidth portion to one or more UEs.

[0157] The timer module 1540 may determine that a timer associated with the first bandwidth portion has expired, wherein switching from the first bandwidth portion to the second bandwidth portion is based on the determination.

[0158] The control signal module 1545 may send control signaling including an indicator for the selection result to one or more UEs. In some examples, the control signal module 1545 may send a second control signaling including a second indicator for the selection result from the first tracking reference signal configuration and the second tracking reference signal configuration to one or more UEs. In some cases, the control signaling includes an RRC signal, a MAC-CE, or a DCI.

[0159] The aperiodic message module 1550 may send a message including an aperiodic tracking reference signal trigger to one or more UEs, wherein the indicator includes the aperiodic tracking reference signal trigger.

[0160] The TCI module 1555 may identify the indicator as a first transmission configuration indicator state, the first transmission configuration indicator state corresponding to a first tracking reference signal configuration. In some cases, the tracking reference signal is quasi-co-located with a first synchronization signal block that is different from a second synchronization signal block that is quasi-co-located with a second tracking reference signal, wherein the tracking reference signal corresponds to the first tracking reference signal configuration and the second tracking reference signal corresponds to the second tracking reference signal configuration.

[0161] The triggering module 1575 may determine to trigger a tracking reference signal configuration for the UEs in the UE set, or the triggering module 1574 may determine to trigger a tracking reference signal configuration for the UE set.

[0162] The first message module 1560 may receive a first message in a random access channel process from one or more UEs. In some cases, the tracking reference signal configuration includes a set of parameters including a tracking reference signal burst length of a certain number of time slots, a tracking reference signal burst period of a certain number of time slots, a number of symbols for a tracking reference signal within a time slot, a tracking reference signal bandwidth, a tracking reference signal subcarrier spacing, or a tracking reference signal symbol spacing within a time slot.

[0163] The second message module 1565 may send a second message in a random access channel process to one or more UEs in response to sending the first message, the second message including an indicator for triggering tracking reference signal transmission. In some cases, the indicator indicates a tracking reference signal configuration.

[0164] Fig.16 A diagram of a system 1600 including a device 1605 supporting techniques for flexible reference signal modes in a wireless communication system according to various aspects of the present disclosure is shown. The device 1605 may be an example of or include components of a device 1305, a device 1405, or a base station 105 as described herein. The device 1605 may include components for two-way voice and data communications, including components for sending and receiving communications (including a communication manager 1610, a network communication manager 1625, a transceiver 1620, an antenna 1625, a memory 1630, a processor 1640, and an inter-station communication manager 1645). These components may communicate electronically via one or more buses (e.g., a bus 1650).

[0165] The communication manager 1610 may send a first tracking reference signal configuration and a second tracking reference signal configuration to one or more UEs, the first tracking reference signal configuration including a first parameter set and the second tracking reference signal configuration including a second parameter set, and send a tracking reference signal to the one or more UEs and based on an indicator for a selection result from the first tracking reference signal configuration and the second tracking reference signal configuration according to the first tracking reference signal configuration or the second tracking reference signal configuration. The communication manager 1610 may also receive a first message in a random access channel process from the one or more UEs, send a second message in a random access channel process to the one or more UEs in response to sending the first message, the second message including an indicator for triggering tracking reference signal transmission, and send a tracking reference signal to the one or more UEs according to the tracking reference signal configuration indicated by the indicator of the second message.

[0166] The network communications manager 1615 may manage communications with the core network (eg, via one or more wired backhaul links). For example, the network communications manager 1615 may manage the transmission of data communications for client devices, such as one or more UEs 115.

[0167] As described above, the transceiver 1620 can communicate bidirectionally via one or more antennas, wired or wireless links. For example, the transceiver 1620 can represent a wireless transceiver and can communicate bidirectionally with another wireless transceiver. The transceiver 1620 may also include a modem for modulating packets and providing the modulated packets to an antenna for transmission, and for demodulating packets received from an antenna.

[0168] In some cases, a wireless device may include a single antenna 1625. However, in some cases, a device may have more than one antenna 1625, which may be capable of transmitting or receiving multiple wireless transmissions simultaneously.

[0169] Memory 1630 may include RAM, ROM, or a combination thereof. Memory 1630 may store computer readable code 1635, which includes instructions that, when executed by a processor (e.g., processor 1640), cause the device to perform various functions described herein. In some cases, memory 1630 may also include BIOS, which may control basic hardware or software operations such as interaction with peripheral components or devices.

[0170] Processor 1640 may include an intelligent hardware device (e.g., a general purpose processor, a DSP, a CPU, a microcontroller, an ASIC, an FPGA, a programmable logic device, a discrete gate or transistor logic component, a discrete hardware component, or any combination thereof). In some cases, processor 1640 may be configured to operate a memory array using a memory controller. In some cases, the memory controller may be integrated into processor 1640. Processor 1640 may be configured to execute computer-readable instructions stored in a memory (e.g., memory 1630) to cause device 1605 to perform various functions (e.g., functions or tasks for supporting techniques for flexible reference signal modes in wireless communication systems).

[0171] The inter-site communication manager 1645 may manage communications with other base stations 105 and may include a controller or scheduler for controlling communications with UE 115 in cooperation with other base stations 105. For example, the inter-site communication manager 1645 may coordinate scheduling of transmissions to UE 115 for various interference mitigation techniques such as beamforming or joint transmission. In some examples, the inter-site communication manager 1645 may provide an X2 interface within an LTE / LTE-A wireless communication network technology to provide communications between base stations 105.

[0172] The code 1635 may include instructions to implement various aspects of the present disclosure, including instructions to support wireless communications. The code 1635 may be stored in a non-transitory computer-readable medium such as a system memory or other type of memory. In some cases, the code 1635 may not be directly executable by the processor 1640, but may cause a computer (e.g., when compiled and executed) to perform the functions described herein.

[0173] Fig.17 A flow chart illustrating a method 1700 for supporting techniques for flexible reference signal modes in a wireless communication system according to aspects of the present disclosure is shown. The operations of the method 1700 may be implemented by a UE 115 or components thereof as described herein. For example, the operations of the method 1700 may be implemented by a UE 115 or components thereof as described herein. Figures 9 to 12 The communication manager described in the embodiment of the present invention performs. In some examples, the UE may execute a set of instructions to control the functional elements of the UE to perform the functions described below. Additionally or alternatively, the UE may use dedicated hardware to perform various aspects of the functions described below.

[0174] At 1705, the UE may receive a first tracking reference signal configuration and a second tracking reference signal configuration from a base station, the first tracking reference signal configuration including a first set of parameters and the second tracking reference signal configuration including a second set of parameters. The operations of 1705 may be performed according to the methods described herein. In some examples, aspects of the operations of 1705 may be performed as described with reference to Figures 9 to 12 Configure the receiver to perform the described

[0175] At 1710, the UE may receive a tracking reference signal from a base station and based on an indicator of a selection result from the first tracking reference signal configuration and the second tracking reference signal configuration, according to the first tracking reference signal configuration or the second tracking reference signal configuration. The operations of 1710 may be performed according to the methods described herein. In some examples, aspects of the operations of 1710 may be performed as described with reference to Figures 9 to 12 Describes the TRS transmitter implementation.

[0176] Fig.18 A flow chart illustrating a method 1800 for supporting techniques for flexible reference signal modes in a wireless communication system according to aspects of the present disclosure is shown. The operations of the method 1800 may be implemented by a UE 115 or components thereof as described herein. For example, the operations of the method 1800 may be implemented by a UE 115 or components thereof as described herein. Figures 9 to 12 The communication manager described in the embodiment of the present invention performs. In some examples, the UE may execute a set of instructions to control the functional elements of the UE to perform the functions described below. Additionally or alternatively, the UE may use dedicated hardware to perform various aspects of the functions described below.

[0177] At 1805, the UE may send a first message in a random access channel process to the base station. The operations of 1805 may be performed according to the methods described herein. In some examples, aspects of the operations of 1805 may be performed as described with reference to Figures 9 to 12 The first message component described is executed.

[0178] At 1810, the UE may receive a second message in a random access channel process from the base station in response to sending the first message, the second message including an indicator for triggering transmission of a tracking reference signal. The operations of 1810 may be performed according to the methods described herein. In some examples, aspects of the operations of 1810 may be performed as described with reference to Figures 9 to 12 The second message component described is executed.

[0179] At 1815, the UE may receive a tracking reference signal from the base station according to the tracking reference signal configuration indicated by the indicator of the second message. The operations of 1815 may be performed according to the methods described herein. In some examples, aspects of the operations of 1815 may be performed as described with reference to Figures 9 to 12Describes the implementation of the TRS components.

[0180] Fig.19 A flow chart illustrating a method 1900 for supporting techniques for flexible reference signal modes in a wireless communication system according to aspects of the present disclosure is shown. The operations of the method 1900 may be implemented by a base station 105 or components thereof as described herein. For example, the operations of the method 1900 may be implemented by a base station 105 or components thereof as described herein. Figures 13 to 16 The communication manager described in the description is executed. In some examples, the base station can execute a set of instructions to control the functional elements of the base station to perform the functions described below. In addition or alternatively, the base station can use dedicated hardware to perform various aspects of the functions described below.

[0181] At 1905, the base station may send a first tracking reference signal configuration and a second tracking reference signal configuration to one or more UEs, the first tracking reference signal configuration including a first set of parameters and the second tracking reference signal configuration including a second set of parameters. The operations of 1905 may be performed according to the methods described herein. In some examples, aspects of the operations of 1905 may be performed as described with reference to Figures 13 to 16 Describes how to configure the transmitter to perform.

[0182] At 1910, the base station may send a tracking reference signal according to the first tracking reference signal configuration or the second tracking reference signal configuration to one or more UEs and based on an indicator of a selection result from the first tracking reference signal configuration and the second tracking reference signal configuration. The operations of 1910 may be performed according to the methods described herein. In some examples, aspects of the operations of 1910 may be performed as described with reference to Figures 13 to 16 The TRS receiver implementation is described.

[0183] Fig. 20 A flow chart illustrating a method 2000 for supporting techniques for flexible reference signal modes in a wireless communication system according to aspects of the present disclosure is shown. The operations of the method 2000 may be implemented by a base station 105 or components thereof as described herein. For example, the operations of the method 2000 may be implemented by a base station 105 or components thereof as described herein. Figures 13 to 16 The communication manager described in the description is executed. In some examples, the base station can execute a set of instructions to control the functional elements of the base station to perform the functions described below. In addition or alternatively, the base station can use dedicated hardware to perform various aspects of the functions described below.

[0184] At 2005, the base station may receive a first message in a random access channel process from one or more UEs. The operations of 2005 may be performed according to the methods described herein. In some examples, aspects of the operations of 2005 may be performed as described with reference to Figures 13 to 16 The first message module described is executed.

[0185] At 2010, the base station may send a second message in a random access channel process to one or more UEs in response to sending the first message, the second message including an indicator for triggering the transmission of a tracking reference signal. The operation of 2010 may be performed according to the method described herein. In some examples, the operation may be performed by referring to Figures 13 to 16 The second messaging module is described to perform various aspects of the operation of 2010.

[0186] At 2015, the base station may send a tracking reference signal to one or more UEs according to the tracking reference signal configuration indicated by the indicator of the second message. The operation of 2015 may be performed according to the method described herein. In some examples, the tracking reference signal may be configured as shown in FIG. Figures 13 to 16 Describes the TRS modules used to perform various aspects of 2015's operations.

[0187] It should be noted that the methods described herein describe possible implementations, and that the operations and steps may be rearranged or otherwise modified, and that other implementations are possible. Furthermore, aspects from two or more methods may be combined.

[0188] The following aspects are given by way of illustration. Examples of the following aspects may be combined with the examples or embodiments shown or discussed with respect to the figures or elsewhere in this document.

[0189] Aspect 1 is a method of wireless communication at a UE, the method comprising: receiving a first tracking reference signal configuration and a second tracking reference signal configuration from a base station, the first tracking reference signal configuration comprising a first parameter set and the second tracking reference signal configuration comprising a second parameter set, and receiving a tracking reference signal from the base station and based on an indicator of a selection result from among the first tracking reference signal configuration and the second tracking reference signal configuration according to the first tracking reference signal configuration or the second tracking reference signal configuration.

[0190] In aspect 2, the method according to aspect 1 includes: identifying a first bandwidth portion for communicating with the base station on a first time resource set, the first bandwidth portion being associated with the first tracking reference signal configuration, wherein the indicator includes the first bandwidth portion, and selecting the first tracking reference signal configuration for the first time resource set based on identifying the first bandwidth portion.

[0191] In aspect 3, the method according to any one of aspects 1-2 includes: identifying a second bandwidth part for communicating with the base station on a second time resource set, the second bandwidth part being associated with the second tracking reference signal configuration, wherein the indicator includes the second bandwidth part, and selecting the second tracking reference signal configuration for the second time resource set based on identifying the second bandwidth part.

[0192] In aspect 4, the method according to any of aspects 1-3 comprises: receiving downlink control information including an indication of the second bandwidth part from the base station.

[0193] In aspect 5, the method according to any one of aspects 1 to 4 comprises determining that a timer associated with the first bandwidth portion may have expired, wherein switching from the first bandwidth portion to the second bandwidth portion may be based on the determination.

[0194] In aspect 6, the method according to any one of aspects 1-5 comprises: receiving control signaling including the indicator for the selection result from the base station, and selecting the first tracking reference signal configuration based on receiving the control signaling.

[0195] In aspect 7, the method according to any one of aspects 1-6 includes: receiving a second control signaling from the base station, the second control signaling including a second indicator for a selection result from the first tracking reference signal configuration and the second tracking reference signal configuration, and selecting the second tracking reference signal configuration for a second tracking reference signal based on receiving the second control signaling.

[0196] In aspect 8, the method according to any one of aspects 1-7 includes receiving the tracking reference signal and the second tracking reference signal from the base station on a same bandwidth portion.

[0197] In aspect 9, the control signaling according to any one of aspects 1 to 8 includes a radio resource control signal, a medium access control control element, or downlink control information.

[0198] In aspect 10, the method according to any one of aspects 1 to 9 comprises: receiving a message including an aperiodic tracking reference signal trigger from the base station, wherein the indicator includes the aperiodic tracking reference signal trigger.

[0199] In aspect 11, the method according to any one of aspects 1-10 includes: selecting the second tracking reference signal configuration based on identifying the indicator that may be triggered by the non-periodic tracking reference signal, and the second tracking reference signal configuration is different from the first tracking reference signal configuration associated with the periodic transmission of the tracking reference signal.

[0200] In aspect 12, the method according to any one of aspects 1-11 includes: identifying that the indicator can be associated with a first transmission configuration indicator state, the first transmission configuration indicator state corresponds to the first tracking reference signal configuration, and based on the indicator, receiving the tracking reference signal from the base station according to the first tracking reference signal configuration based on identifying the indicator that can be the first transmission configuration indicator state.

[0201] Aspect 13 may include any of Aspects 1-12, wherein a first synchronization signal block may be quasi-co-located with a first transmission configuration indicator state, and a second synchronization signal block may be quasi-co-located with a second transmission configuration indicator state, and wherein the indicator includes a characteristic associated with the first synchronization signal block or the second synchronization signal block.

[0202] In aspect 14, the first parameter set, the second parameter set or both of the above-described aspects 1-13 include a tracking reference signal burst length of a certain number of time slots, a tracking reference signal burst period of the certain number of time slots, the number of symbols for the tracking reference signal in a time slot, a tracking reference signal bandwidth, a tracking reference signal subcarrier spacing, or a tracking reference signal symbol spacing in the time slot.

[0203] Aspect 15 is a system or apparatus, comprising means for implementing the method or apparatus according to any one of aspects 1-14.

[0204] Aspect 16 is a non-transitory computer-readable medium storing instructions executable by one or more processors to cause the one or more processors to implement the method according to any one of aspects 1-14.

[0205] Aspect 17 is a system comprising one or more processors and a memory in electronic communication with the one or more processors, the memory storing instructions executable by the one or more processors to enable the system or device to implement a method as described in any one of aspects 1-14.

[0206] Aspect 18 is a method of wireless communication at a UE, comprising: sending a first message in a random access channel process to a base station, receiving a second message in the random access channel process from the base station in response to sending the first message, the second message including an indicator for triggering transmission of a tracking reference signal, and receiving a tracking reference signal from the base station according to a tracking reference signal configuration indicated by the indicator of the second message.

[0207] Aspect 19 may include the method of aspect 18, wherein the indicator indicates the selected tracking reference signal configuration.

[0208] Aspect 20 may include a method according to any one of Aspects 18-19, wherein the tracking reference signal configuration includes a parameter set, the parameter set including a tracking reference signal burst length of a certain number of time slots, a tracking reference signal burst period of the certain number of time slots, the number of symbols for the tracking reference signal in the time slot, the tracking reference signal bandwidth, the tracking reference signal subcarrier spacing, or the tracking reference signal symbol spacing in the time slot.

[0209] Aspect 21 is a system or apparatus, comprising means for implementing the method or apparatus according to any one of aspects 18-20.

[0210] Aspect 22 is a non-transitory computer-readable medium storing instructions executable by one or more processors to cause the one or more processors to implement the method according to any one of aspects 18-20.

[0211] Aspect 23 is a system comprising one or more processors and a memory in electronic communication with the one or more processors, the memory storing instructions executable by the one or more processors to cause the system or device to implement a method as described in any one of aspects 18-20.

[0212] Aspect 24 is a method of wireless communication at a base station, comprising: sending a first tracking reference signal configuration and a second tracking reference signal configuration to one or more UEs, the first tracking reference signal configuration including a first parameter set and the second tracking reference signal configuration including a second parameter set, and sending a tracking reference signal according to the first tracking reference signal configuration or the second tracking reference signal configuration to the one or more UEs and based on an indicator of a selection result from among the first tracking reference signal configuration and the second tracking reference signal configuration.

[0213] In aspect 25, the method according to aspect 24 includes: identifying a first bandwidth part for receiving the tracking reference signal, the first bandwidth part being associated with the first tracking reference signal configuration, wherein the indicator includes the first bandwidth part; and selecting the first tracking reference signal configuration based on identifying the first bandwidth part.

[0214] In aspect 26, the method according to any one of aspects 24-25 includes: identifying a second bandwidth part for transmitting the tracking reference signal, the second bandwidth part being associated with the second tracking reference signal configuration, wherein the indicator includes the second bandwidth part, switching from the first bandwidth part to the second bandwidth part based on identifying the second bandwidth part, and selecting the second tracking reference signal configuration based on switching from the first bandwidth part to the second bandwidth part.

[0215] In aspect 27, the method according to any of aspects 24-26 comprises sending downlink control information including an indication of the second bandwidth part to the one or more UEs.

[0216] In aspect 28, the method according to any of aspects 24-27 comprises determining that a timer associated with the first bandwidth portion may have expired, wherein switching from the first bandwidth portion to the second bandwidth portion may be based on the determination.

[0217] In aspect 29, the method according to any one of aspects 24-28 comprises: sending control signaling including the indicator for the selection result to the one or more UEs, and selecting the first tracking reference signal configuration based on sending the control signaling.

[0218] In aspect 30, the method according to any one of aspects 24-29 includes: sending a second control signaling to the one or more UEs, the second control signal including a second indicator for a selection result from among the first tracking reference signal configuration and the second tracking reference signal configuration, and selecting the second tracking reference signal configuration for the second tracking reference signal based on sending the second control signaling.

[0219] In aspect 31, the method according to any of aspects 24-30 comprises sending the tracking reference signal and the second tracking reference signal to the one or more UEs according to the same bandwidth portion configuration.

[0220] In aspect 32, the control signaling according to any one of aspects 24-31 comprises a radio resource control signal, a medium access control control element or downlink control information.

[0221] In aspect 33, the method according to any of aspects 24-32 includes: sending a message including an aperiodic tracking reference signal trigger to the one or more UEs, wherein the indicator includes the aperiodic tracking reference signal trigger.

[0222] In aspect 34, the method according to any of aspects 24-33 comprises selecting the second tracking reference signal configuration based on sending the message, the second tracking reference signal configuration being different from the first tracking reference signal configuration associated with the periodic transmission of the tracking reference signal.

[0223] In aspect 35, the method according to any one of aspects 24-34 includes: identifying the indicator that can be a first transmission configuration indicator state, the first transmission configuration indicator state corresponds to the first tracking reference signal configuration, and based on the indicator, based on identifying the indicator that can be the first transmission configuration indicator state, receiving the tracking reference signal according to the first tracking reference signal configuration.

[0224] Aspect 36 may include any of Aspects 24-35, wherein the tracking reference signal may be quasi-co-located with a first synchronization signal block, the first synchronization signal block is different from a second synchronization signal block quasi-co-located with a second tracking reference signal, wherein the tracking reference signal corresponds to the first tracking reference signal configuration and the second tracking reference signal corresponds to the second tracking reference signal configuration.

[0225] In aspect 37, the first parameter set, the second parameter set or both of the above-described aspects 24-36 include a tracking reference signal burst length of a certain number of time slots, a tracking reference signal burst period of the certain number of time slots, the number of symbols for the tracking reference signal in a time slot, a tracking reference signal bandwidth, a tracking reference signal subcarrier spacing, or a tracking reference signal symbol spacing in the time slot.

[0226] Aspect 38 is a system or apparatus, comprising means for implementing the method or apparatus according to any one of aspects 24-37.

[0227] Aspect 39 is a non-transitory computer-readable medium storing instructions executable by one or more processors to cause the one or more processors to implement the method as described in any one of aspects 24-37.

[0228] Aspect 40 is a system comprising one or more processors and a memory in electronic communication with the one or more processors, the memory storing instructions executable by the one or more processors to cause the system or device to implement a method as described in any one of aspects 24-37.

[0229] Aspect 41 is a method for wireless communication at a base station, comprising: receiving a first message in a random access channel process from one or more UEs, sending a second message in the random access channel process to the one or more UEs in response to sending the first message, the second message including an indicator for triggering transmission of a tracking reference signal, and sending a tracking reference signal to the one or more UEs according to the tracking reference signal configuration indicated by the indicator of the second message.

[0230] Aspect 42 may include the method of aspect 41, wherein the indicator indicates the tracking reference signal configuration.

[0231] In aspect 43, the method according to any one of aspects 41-42 comprises: determining to trigger the tracking reference signal configuration for a UE in a set of UEs, or determining to trigger the tracking reference signal configuration for the set of UEs.

[0232] Aspect 44 may include a method according to any one of Aspects 41-43, wherein the tracking reference signal configuration includes a parameter set, the parameter set including a tracking reference signal burst length of a certain number of time slots, a tracking reference signal burst period of the certain number of time slots, the number of symbols for the tracking reference signal in the time slot, the tracking reference signal bandwidth, the tracking reference signal subcarrier spacing, or the tracking reference signal symbol spacing in the time slot.

[0233] Aspect 45 is a system or apparatus, comprising means for implementing the method or apparatus according to any one of aspects 41-43.

[0234] Aspect 46 is a non-transitory computer-readable medium storing instructions executable by one or more processors to cause the one or more processors to implement the method as described in any one of aspects 41-43.

[0235] Aspect 47 is a system comprising one or more processors and a memory in electronic communication with the one or more processors, the memory storing instructions executable by the one or more processors to cause the system or device to implement a method as described in any one of Aspects 41-43.

[0236] Examples of these aspects may be combined with examples or embodiments disclosed in other implementations.

[0237] Although aspects of LTE, LTE-A, LTE-A Pro, or NR systems may be described for purposes of example, and LTE, LTE-A, LTE-A Pro, or NR terminology may be used in much of the description, the techniques described herein may be applicable beyond LTE, LTE-A, LTE-A Pro, or NR applications. For example, the techniques described may be applicable to various 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.

[0238] The information and signals described herein may be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips mentioned throughout the above description may be represented by voltage, current, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

[0239] The various illustrative blocks and modules described in conjunction with the disclosure herein may be implemented or executed with a general purpose processor, a DSP, an ASIC, an 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. A general purpose processor may be a microprocessor, but alternatively, the processor may be any conventional 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, a plurality of microprocessors, a combination of one or more microprocessors with a DSP core, or any other such configuration).

[0240] 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 as one or more instructions or codes on or transmitted via a computer-readable medium. Other examples and implementations are within the scope of this disclosure and the appended claims. For example, due to the nature of software, the functions described above may be implemented using software executed by a processor, hardware, firmware, hardwiring, or a combination of any of these items. Features used to implement the functions may also be physically located in various locations, including being distributed so that parts of the functions are implemented at different physical locations.

[0241] Computer readable medium includes both non-transitory computer storage medium and communication medium, and the communication medium includes any medium that promotes to transfer computer program from one place to another place.Non-transitory storage medium can be any available medium that can be accessed by general or special-purpose computer.As an example and not limitation, non-transitory computer readable medium can include RAM, ROM, electrically erasable programmable ROM (EEPROM), flash memory, compact disc (CD) ROM or other optical disk storage, disk storage or other disk storage device, or can be used for carrying or storing desired program code unit in the form of instruction or data structure and can be accessed by general or special-purpose computer or general or special-purpose processor computer any other non-transitory medium.Moreover, any connection is appropriately referred to as computer readable medium.For example, if software is sent from website, server or other remote source using coaxial cable, optical cable, twisted pair, digital subscriber line (DSL) or wireless technology (for example, infrared, radio and microwave), then coaxial cable, optical cable, twisted pair, DSL or wireless technology such as infrared, radio and microwave are included in the definition of computer readable medium. Disk and disc as used herein include CDs, laser discs, optical discs, digital versatile discs (DVDs), floppy disks and Blu-ray discs, where disks usually reproduce data magnetically, while discs reproduce data optically with lasers. Combinations of the above are also included within the scope of computer-readable media.

[0242] As used herein, including in the claims, "or" as used in a list of items (e.g., a list of items beginning with a phrase such as "at least one" or "one or more") indicates an inclusive list, so that, for example, a list of 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). Moreover, as used herein, the phrase "based on" should not be interpreted as a reference to a closed set of conditions. For example, an exemplary step described as "based on condition A" can be based on both condition A and condition B without departing from the scope of the present disclosure. In other words, as used herein, the phrase "based on" should be interpreted in the same manner as the phrase "based at least in part on."

[0243] In the accompanying drawings, similar components or features may have the same reference numeral. In addition, various components of the same type may be distinguished by following the reference numeral with a dash and a second reference numeral that distinguishes between similar components. If only the first reference numeral is used in the specification, the description applies to any similar component having the same first reference numeral, regardless of the second reference numeral or other subsequent reference numerals.

[0244] The description given herein in conjunction with the accompanying drawings describes example configurations and does not represent all examples that can be implemented or within the scope of the claims. The term "exemplary" used herein means "used as an example, instance, or illustration," rather than "preferred" or "more advantageous than other examples." The specific implementation includes specific details to provide an understanding of the described technology. However, these technologies can be implemented without these specific details. In some cases, well-known structures and devices are shown in block diagram form to avoid obscuring the concepts of the examples described.

[0245] The description herein is provided to enable one of ordinary skill in the art to make or use the present disclosure. Various modifications to the present disclosure will be apparent to one of ordinary skill in the art, and the general principles defined herein may be applied to other variations without departing from the scope of the present disclosure. Therefore, the present disclosure is not limited to the examples and designs described herein, but is intended to conform to 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, from a base station, a first tracking reference signal configuration associated with a first bandwidth portion and a second tracking reference signal configuration associated with a second bandwidth portion, the first tracking reference signal configuration comprising a first set of parameters and the second tracking reference signal configuration comprising a second set of parameters; identifying the first bandwidth portion for communication with the base station on a first set of time resources and the second bandwidth portion for communication with the base station on a second set of time resources, wherein the first set of time resources is different from the second set of time resources; selecting the first tracking reference signal configuration for the first set of time resources based at least in part on the first tracking reference signal configuration being associated with the first bandwidth part; and Based at least in part on the selection, a first tracking reference signal is received from the base station according to the first tracking reference signal configuration.

2. The method according to claim 1, further comprising: identifying the second bandwidth portion for communication with the base station over the second set of time resources, the second bandwidth portion being associated with the second tracking reference signal configuration; as well as The second tracking reference signal configuration for the second set of time resources is selected based at least in part on the second tracking reference signal configuration being associated with the second bandwidth part.

3. The method according to claim 2, further comprising: Downlink control information including an indication of the second bandwidth portion is received from the base station.

4. The method according to claim 2, further comprising: A determination is made that a timer associated with the first bandwidth portion has expired, wherein switching from the first bandwidth portion to the second bandwidth portion is based at least in part on the determination.

5. The method according to claim 1, wherein: The first parameter set, the second parameter set or both include a tracking reference signal burst length of a certain number of time slots, a tracking reference signal burst period of the certain number of time slots, the number of symbols for the tracking reference signal burst in a time slot, a tracking reference signal bandwidth, a tracking reference signal subcarrier spacing, or a tracking reference signal symbol spacing in the time slot.

6. An apparatus for wireless communication at a user equipment (UE), comprising: one or more processors, one or more memories coupled to the one or more processors; as well as Instructions stored in the one or more memories and executable by the one or more processors to cause the apparatus to: receiving, from a base station, a first tracking reference signal configuration associated with a first bandwidth portion and a second tracking reference signal configuration associated with a second bandwidth portion, the first tracking reference signal configuration comprising a first set of parameters and the second tracking reference signal configuration comprising a second set of parameters; identifying the first bandwidth portion for communication with the base station on a first set of time resources and the second bandwidth portion for communication with the base station on a second set of time resources, wherein the first set of time resources is different from the second set of time resources; selecting the first tracking reference signal configuration for the first set of time resources based at least in part on the first tracking reference signal configuration being associated with the first bandwidth part; and Based at least in part on the selection, a first tracking reference signal is received from the base station according to the first tracking reference signal configuration.

7. The device according to claim 6, wherein: The one or more processors are further operable, individually or collectively, to execute the instructions to cause the apparatus to: identifying the second bandwidth portion for communication with the base station over the second set of time resources, the second bandwidth portion being associated with the second tracking reference signal configuration; as well as The second tracking reference signal configuration for the second set of time resources is selected based at least in part on the second tracking reference signal configuration being associated with the second bandwidth part.

8. The device according to claim 7, wherein: The one or more processors are further operable, individually or collectively, to execute the instructions to cause the apparatus to: Downlink control information including an indication of the second bandwidth portion is received from the base station.

9. The device according to claim 7, wherein: The one or more processors are further operable, individually or collectively, to execute the instructions to cause the apparatus to: A determination is made that a timer associated with the first bandwidth portion has expired, wherein switching from the first bandwidth portion to the second bandwidth portion is based at least in part on the determination.

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