CN117099340A - Frequency tracking and timing tracking using broadband reference signals - Google Patents

Abstract

Certain aspects of the present disclosure provide techniques for frequency tracking and timing tracking using a wideband Reference Signal (RS). A method executable by a User Equipment (UE) includes monitoring a wideband RS from a network entity when one or more conditions are met, the wideband RS occupying frequency resources that are wider than a Tracking Reference Signal (TRS) transmitted by the network entity; and performing at least one of frequency tracking or timing tracking based on the monitoring.

Description

Frequency tracking and timing tracking using broadband reference signals

Cross Reference to Related Applications

The present application claims the benefit and priority of U.S. application Ser. No.17/712,956, filed 4 at 2022, and U.S. provisional patent application Ser. No.63/171,517, filed 4 at 2021, which are assigned to the assignee of the present application and are incorporated herein by reference as if fully set forth below and for all applicable purposes.

Background

Aspects of the present disclosure relate to wireless communications, and more particularly, to techniques for frequency tracking and/or timing tracking using a wideband Reference Signal (RS). Wireless communication systems are widely deployed to provide various telecommunication services such as telephony, video, data, messaging, broadcast, or other similar types of services. These wireless communication systems may employ multiple-access techniques capable of supporting communication with multiple users by sharing available system resources (e.g., bandwidth, transmit power, or other resources) with the users. The multiple access technique may rely on any of code division, time division, frequency division, orthogonal frequency division, single carrier frequency division, or time division synchronous code division, to name a few examples. These and other multiple access techniques have been adopted in various telecommunications standards to provide a common protocol that enables different wireless devices to communicate at the urban, national, regional, and even global levels.

Despite the tremendous technological advances made over the years in wireless communication systems, challenges remain. For example, complex and dynamic environments may still attenuate or block signals between the wireless transmitter and the wireless receiver, disrupting the various wireless channel measurement and reporting mechanisms established for managing and optimizing the use of limited wireless channel resources. Accordingly, there is a need for further improvements in wireless communication systems to overcome various challenges.

SUMMARY

Certain aspects may be implemented in a wireless communication method performed by a User Equipment (UE). The method generally includes monitoring a wideband Reference Signal (RS) from a network entity when one or more conditions are met, the wideband RS occupying frequency resources that are wider than a Tracking Reference Signal (TRS) transmitted by the network entity; and performing at least one of frequency tracking or timing tracking based on the monitoring.

Certain aspects may be implemented in a processing system for wireless communication by a UE. The processing system generally includes a memory having computer-executable instructions; and one or more processors configured to execute the computer-executable instructions and cause the processing system to: monitoring a wideband RS from a network entity when one or more conditions are met, the wideband RS occupying frequency resources that are more wideband than a TRS transmitted by the network entity; and performing at least one of frequency tracking or timing tracking based on the monitoring.

Certain aspects may be implemented in an apparatus for wireless communication by a UE. The apparatus may include means for monitoring a wideband RS from a network entity when one or more conditions are met, the wideband RS occupying frequency resources that are wider than a TRS transmitted by the network entity; and means for performing at least one of frequency tracking or timing tracking based on the monitoring.

Certain aspects may be implemented in a non-transitory computer-readable medium for wireless communication by a UE. The non-transitory computer-readable medium may include computer-executable instructions that, when executed by one or more processors of a processing system, cause the processing system to: monitoring a wideband RS from a network entity when one or more conditions are met, the wideband RS occupying frequency resources that are more wideband than a TRS transmitted by the network entity; and performing at least one of frequency tracking or timing tracking based on the monitoring.

Certain aspects may be implemented in a computer program product for wireless communication by a UE embodied on a computer-readable storage medium. The computer-readable storage medium may include code for: monitoring a wideband RS from a network entity when one or more conditions are met, the wideband RS occupying frequency resources that are more wideband than a TRS transmitted by the network entity; and performing at least one of frequency tracking or timing tracking based on the monitoring.

Certain aspects may be implemented in a method of wireless communication by a network entity. The method generally includes detecting when one or more conditions are met to trigger transmission of a wideband Reference Signal (RS) that occupies frequency resources of a wider frequency band than a Tracking Reference Signal (TRS) transmitted by the network entity; and transmitting the wideband RS to the UE based on the detecting.

Certain aspects may be implemented in a processing system for wireless communication by a network entity. The processing system generally includes a memory having computer-executable instructions; and one or more processors configured to execute the computer-executable instructions and cause the processing system to: detecting when one or more conditions are met to trigger transmission of a wideband Reference Signal (RS) that occupies a frequency resource that is wider than a Tracking Reference Signal (TRS) transmitted by the network entity; and transmitting the wideband RS to the UE based on the detecting.

Certain aspects may be implemented in an apparatus for wireless communication by a network entity. The apparatus may include means for detecting when one or more conditions are met to trigger transmission of a wideband Reference Signal (RS) that occupies frequency resources of a wider frequency band than a Tracking Reference Signal (TRS) transmitted by the network entity; and means for transmitting the wideband RS to the UE based on the detection.

Certain aspects may be implemented in a non-transitory computer-readable medium for wireless communication by a network entity. The non-transitory computer-readable medium may include computer-executable instructions that, when executed by one or more processors of a processing system, cause the processing system to: detecting when one or more conditions are met to trigger transmission of a wideband Reference Signal (RS) that occupies a frequency resource that is wider than a Tracking Reference Signal (TRS) transmitted by the network entity; and transmitting the wideband RS to the UE based on the detecting.

Certain aspects may be implemented in a computer program product embodied on a computer readable storage medium for wireless communication by a network entity. The apparatus may include means for detecting when one or more conditions are met to trigger transmission of a wideband Reference Signal (RS) that occupies frequency resources of a wider frequency band than a Tracking Reference Signal (TRS) transmitted by the network entity; and transmitting the wideband RS to the UE based on the detecting.

For purposes of illustration, the following description and the annexed drawings set forth certain features.

Brief Description of Drawings

The drawings depict certain features of the aspects described herein and are not intended to limit the scope of the disclosure.

Fig. 1 is a block diagram conceptually illustrating an example wireless communication network.

Fig. 2 is a block diagram conceptually illustrating aspects of an example of a base station and user equipment.

Fig. 3A-3D depict various example aspects of a data structure for a wireless communication network.

Fig. 4 shows a time-frequency resource grid illustrating example resource allocations to a TRS.

Fig. 5 is a flow chart illustrating example operations of wireless communication by a base station.

Fig. 6 is a flow chart illustrating example operations of wireless communication by a user equipment.

Fig. 7 is a call flow diagram illustrating example operations between a network entity and a user equipment for frequency tracking and timing tracking using a wideband Reference Signal (RS).

Fig. 8 and 9 depict aspects of an example communication device.

Detailed Description

Aspects of the present disclosure provide apparatuses, methods, processing systems, and computer-readable media for frequency tracking, timing tracking, or both frequency and time tracking by a User Equipment (UE) using a wideband Reference Signal (RS).

The wideband RS may be used by the UE for such tracking before the UE is configured with a relatively narrowband Tracking Reference Signal (TRS), which is typically used for such purposes. The wideband RS may be used in addition to or in place of the conventional TRS. As such, the techniques proposed herein may result in less frequent TRS transmissions and, thus, reduced TRS overhead.

Introduction to Wireless communication networks

Fig. 1 depicts an example of a wireless communication system 100 in which aspects described herein may be implemented. For example, the wireless communication system 100 can include a Base Station (BS) 102 having a tracking component 199 configured to perform one or more of the operations illustrated in fig. 6, as well as other operations described herein for frequency tracking and timing tracking using wideband Reference Signals (RSs). The wireless communication system 100 can also include a user equipment 104 having a tracking component 198 configured to perform one or more of the operations illustrated in fig. 5, as well as other operations described herein for frequency tracking and timing tracking using wideband RSs.

In general, wireless communication system 100 includes a BS102, a user UE 104, one or more core networks, such as an Evolved Packet Core (EPC) 160 and a 5G core (5 GC) network 190, that interoperate to provide wireless communication services.

The base station 102 may provide an access point for the user equipment 104 to the EPC 160 and/or 5gc 190 and may perform one or more of the following functions: user data delivery, radio channel ciphering and ciphering, integrity protection, header compression, mobility control functions (e.g., handover, dual connectivity), inter-cell interference coordination, connection setup and release, load balancing, distribution of non-access stratum (NAS) messages, NAS node selection, synchronization, radio Access Network (RAN) sharing, multimedia Broadcast Multicast Services (MBMS), subscriber and equipment tracking, RAN Information Management (RIM), paging, positioning, delivery of alert messages, and other functions. In various contexts, BS102 may include and/or be referred to as a gNB, a node B, an eNB, a ng-eNB (e.g., an eNB that has been enhanced to provide connectivity to both EPC 160 and 5gc 190), an access point, a base transceiver station, a radio base station, a radio transceiver, a transceiver function, or a transmission receiving point.

The base station 102 communicates wirelessly with the UE 104 via a communication link 120. Each base station 102 may provide communication coverage for various geographic coverage areas 110 that may overlap in some cases. For example, a small cell 102 '(e.g., a low power base station) may have a coverage area 110' that overlaps with the coverage area 110 of one or more macro cells (e.g., a high power base station).

The communication link 120 between the base station 102 and the UE 104 may include Uplink (UL) (also known as reverse link) transmissions from the user equipment 104 to the base station 102 and/or Downlink (DL) (also known as forward link) transmissions from the base station 102 to the user equipment 104. In aspects, communication link 120 may use multiple-input multiple-output (MIMO) antenna techniques including spatial multiplexing, beamforming, and/or transmit diversity.

Examples of UEs 104 include a cellular phone, a smart phone, a Session Initiation Protocol (SIP) phone, a laptop, a Personal Digital Assistant (PDA), a satellite radio, a global positioning system, a multimedia device, a video device, a digital audio player, a camera, a game console, a tablet device, a smart device, a wearable device, a vehicle, an electricity meter, an air pump, a large or small kitchen appliance, a healthcare device, an implant, a sensor/actuator, a display, or other similar devices. Some UEs 104 may be internet of things (IoT) devices (e.g., parking meters, air pumps, ovens, vehicles, heart monitors, or other IoT devices), always-on (AON) devices, or edge processing devices. The UE 104 may also be more generally referred to as a station, mobile station, subscriber station, mobile unit, subscriber unit, wireless unit, remote unit, mobile device, wireless communication device, remote device, mobile subscriber station, access terminal, mobile terminal, wireless terminal, remote terminal, handset, user agent, mobile client, or client.

Fig. 2 depicts aspects of an example Base Station (BS) 102 and User Equipment (UE) 104.

In general, base station 102 includes various processors (e.g., one or more processors such as processing 220, 230, 238, and 240), antennas 234a-t (collectively 234), transceivers 232a-t (collectively 232) including modulators and demodulators, and other aspects that enable wireless transmission of data (e.g., data source 212) and wireless reception of data (e.g., data sink 239). For example, the base station 102 may send and receive data between itself and the user equipment 104.

The base station 102 includes a controller/processor 240 that may be configured to implement various functions related to wireless communications. In the depicted example, controller/processor 240 includes tracking component 241, which may represent tracking component 199 of fig. 1. It is noted that although depicted as an aspect of controller/processor 240, tracking component 241 may additionally or alternatively be implemented in various other aspects of base station 102 in other implementations.

In general, the user equipment 104 includes various processors (e.g., one or more processors such as processors 258, 264, 266, and 280), antennas 252a-r (collectively 252), transceivers 254a-r (collectively 254) including modulators and demodulators, and other aspects that enable wireless transmission of data (e.g., source data 262) and wireless reception of data (e.g., data sink 260).

The user equipment 104 includes a controller/processor 280 that may be configured to implement various functions related to wireless communications. In the depicted example, controller/processor 280 includes tracking component 281, which may represent tracking component 198 of fig. 1. Notably, while depicted as an aspect of the controller/processor 280, the tracking component 281 may additionally or alternatively be implemented in various other aspects of the user equipment 104 in other implementations.

Overview of decomposed network entities

In various aspects, a network entity or network node may be implemented as an aggregated base station, a decomposed base station, an Integrated Access and Backhaul (IAB) node, a relay node, a sidelink node, to name just a few examples.

The split base station architecture may include one or more Central Units (CUs) that may communicate directly with the core network via a backhaul link, or indirectly with the core network through one or more split base station units, such as Near real-time (Near-RT) RAN Intelligent Controllers (RIC) via E2 links, or Non-real-time (Non-RT) RIC associated with a Service Management and Orchestration (SMO) framework, or both. A CU may communicate with one or more Distributed Units (DUs) via a respective mid-range link, such as an F1 interface. The DUs may communicate with one or more Radio Units (RUs) via respective outbound links. The RU may communicate with respective UEs via one or more Radio Frequency (RF) access links. In some implementations, UE 120 may be served by multiple RUs simultaneously.

Each of these units (i.e., DU, RU, and near RT RIC, non-RT RIC, and SMO frameworks) may include or be coupled to one or more interfaces configured to receive or transmit signals, data, or information (collectively referred to as signals) via wired or wireless transmission media. Each of the units, or an associated processor or controller that provides instructions to a communication interface of the units, may be configured to communicate with one or more of the other units via a transmission medium. For example, the units may include a wired interface configured to receive or transmit signals to one or more of the other units over a wired transmission medium. Additionally, the units may include a wireless interface that may include a receiver, transmitter, or transceiver (such as a Radio Frequency (RF) transceiver) configured to receive or transmit signals to one or more of the other units, or both, over a wireless transmission medium.

In some aspects, a CU may host one or more higher layer control functions. Such control functions may include Radio Resource Control (RRC), packet Data Convergence Protocol (PDCP), service Data Adaptation Protocol (SDAP), etc. Each control function may be implemented with an interface configured to communicate signals with other control functions hosted by the CU. A CU may be configured to handle user plane functionality (i.e., central unit-user plane (CU-UP)), control plane functionality (i.e., central unit-control plane (CU-CP)), or a combination thereof. In some implementations, a CU may be logically split into one or more CU-UP units and one or more CU-CP units. When implemented in an O-RAN configuration, the CU-UP unit may communicate bi-directionally with the CU-CP unit via an interface, such as an E1 interface. A CU may be implemented to communicate with DUs for network control and signaling, as desired.

The DUs may correspond to logic units that include one or more base station functions to control the operation of one or more RUs. In some aspects, DUs may host one or more of a Radio Link Control (RLC) layer, a Medium Access Control (MAC) layer, and one or more high Physical (PHY) layers, such as modules for Forward Error Correction (FEC) encoding and decoding, scrambling, modulation and demodulation, etc., depending at least in part on a functional partitioning, such as defined by the third generation partnership project (3 GPP). In some aspects, the DU may further host one or more lower PHY layers. Each layer (or module) may be implemented with an interface configured to communicate signals with other layers (and modules) hosted by the DU or with control functions hosted by the CU.

The lower layer functionality may be implemented by one or more RUs. In some deployments, RU controlled by DUs may correspond to logical nodes hosting RF processing functions or lower PHY layer functions (such as performing Fast Fourier Transforms (FFTs), inverse FFTs (iffts), digital beamforming, physical Random Access Channel (PRACH) extraction and filtering, etc.), or both, based at least in part on functional partitioning (such as lower layer functional partitioning). In such an architecture, RU(s) may be implemented to handle over-the-air (OTA) communications with one or more UEs. In some implementations, the real-time and non-real-time aspects of control and user plane communication with RU(s) may be controlled by the corresponding DUs. In some scenarios, this configuration may enable the DU(s) and CU(s) to be implemented in a cloud-based RAN architecture, such as a vRAN architecture.

The SMO framework may be configured to support RAN deployment and provisioning of non-virtualized and virtualized network elements. For non-virtualized network elements, the SMO framework may be configured to support deployment of dedicated physical resources for RAN coverage requirements that may be managed via operation and maintenance interfaces (such as O1 interfaces). For virtualized network elements, the SMO framework may be configured to interact with a Cloud computing platform, such as an open Cloud (O-Cloud), to perform network element lifecycle management (such as instantiating the virtualized network elements) via a Cloud computing platform interface, such as an O2 interface. Such virtualized network elements may include, but are not limited to, CUs, DUs, RUs, and near RT RICs. In some implementations, the SMO framework may communicate with hardware aspects of the 4G RAN, such as an open eNB (O-eNB), via an O1 interface. Additionally, in some implementations, the SMO framework may communicate directly with one or more RUs via an O1 interface. The SMO framework may also include a non-RT RIC configured to support the functionality of the SMO framework.

The non-RT RIC may be configured to include logic functions that enable non-real-time control and optimization of RAN elements and resources, artificial intelligence/machine learning (AI/ML) workflows including model training and updating, or policy-based guidance of applications/features in a near-RT RIC. The non-RT RIC may be coupled to or in communication with a near RT RIC (such as via an A1 interface). The near RT RIC may be configured to include logic functions that enable near real-time control and optimization of RAN elements and resources via data collection and actions through an interface (such as via an E2 interface) that connects one or more CUs, one or more DUs, or both, and an O-eNB with the near RT RIC.

In some implementations, to generate an AI/ML model to be deployed in a near RT RIC, a non-RT RIC may receive parameters or external rich information from an external server. Such information may be utilized by a near RT RIC and may be received at SMO framework or non-RT RIC from a non-network data source or from a network function. In some examples, the non-RT RIC or near-RT RIC may be configured to tune RAN behavior or performance. For example, a non-RT RIC may monitor long-term trends and patterns of performance and employ AI/ML models to perform corrective actions through SMO frameworks (such as via reconfiguration of O1) or via creation of RAN management policies (such as A1 policies).

Overview of example data structures

Fig. 3A-3D depict aspects of a data structure for a wireless communication network, such as the wireless communication system 100 of fig. 1. Specifically, fig. 3A is a diagram 300 illustrating an example of a first subframe within a 5G (e.g., 5G NR) frame structure, fig. 3B is a diagram 330 illustrating an example of a DL channel within a 5G subframe, fig. 3C is a diagram 350 illustrating an example of a second subframe within a 5G frame structure, and fig. 3D is a diagram 380 illustrating an example of a UL channel within a 5G subframe.

Further discussion regarding fig. 1, 2, and 3A-3D is provided later in this disclosure.

Introduction to millimeter wave (mmWave) wireless communication

In wireless communications, the electromagnetic spectrum is typically subdivided into various categories, bands, channels, or other features. Subdivision is typically provided based on wavelength and frequency, where frequency may also be referred to as a carrier, subcarrier, channel, tone, or subband.

In 5G, two initial operating bands have been identified as frequency range designation FR1 (410 MHz-7.125 GHz) and FR2 (24.25 GHz-52.6 GHz). The frequency between FR1 and FR2 is commonly referred to as the mid-band frequency. Although a portion of FR1 is greater than 6GHz, FR1 is often (interchangeably) referred to as the "sub-6 GHz" band in various documents and articles. Similar naming problems sometimes occur with respect to FR2, which is often (interchangeably) referred to in various documents and articles as the "millimeter wave" band, although it is different from the Extremely High Frequency (EHF) band (30 GHz-300 GHz) identified by the International Telecommunications Union (ITU) as the "millimeter wave" (mmW "or" mmWave ") band, because the wavelengths at these frequencies are between 1 and 10 millimeters. The radio waves in this band may be referred to as millimeter waves. Near mmWave can be extended down to 3GHz frequencies with 100 mm wavelength. The ultra-high frequency (SHF) band extends between 3GHz and 30GHz, which is also known as a centimeter wave.

In view of the above, unless specifically stated otherwise, it is to be understood that, if used herein, the term "sub-6 GHz" or the like may broadly represent frequencies that may be less than 6GHz, may be within FR1, or may include mid-band frequencies. Further, unless specifically stated otherwise, it should be understood that, if used herein, the term "millimeter wave" or the like may broadly represent frequencies that may include mid-band frequencies, may be within FR2, or may be within the EHF band.

Communications using the mmWave/near mmWave radio frequency band (e.g., 3GHz-300 GHz) may have higher path loss and shorter range than lower frequency communications. Accordingly, in fig. 1, mmWave base station 180 may utilize beamforming 182 with UE 104 to improve path loss and range. To this end, the base station 180 and the UE 104 may each include multiple antennas, such as antenna elements, antenna panels, and/or antenna arrays to facilitate beamforming.

In some cases, the base station 180 may transmit the beamformed signals to the UE 104 in one or more transmit directions 182'. The UE 104 may receive the beamformed signals from the base station 180 in one or more receive directions 182 ". The UE 104 may also transmit the beamformed signals to the base station 180 in one or more transmit directions 182 ". The base station 180 may receive the beamformed signals from the UEs 104 in one or more receive directions 182'. The base station 180 and the UE 104 may then perform beam training to determine the best receive direction and transmit direction for each of the base station 180 and the UE 104. It is noted that the transmission direction and the reception direction of the base station 180 may be the same or different. Similarly, the transmit direction and the receive direction of the UE 104 may be the same or different.

Aspects related to TRS

In the fifth generation (5G) New Radio (NR), timing error correction is typically performed using a two-step procedure. In a first step, a Synchronization Signal Block (SSB) is used for synchronization purposes to determine a coarse timing for the start of a time slot (e.g., a Fast Fourier Transform (FFT) window). In the second step, a Tracking Reference Signal (TRS) is used to refine the timing and track any drift in the timing error.

In general, SSB-based timing error correction is mainly used during the initial access procedure, while TRS-based timing error correction is used for connected mode operation. Thus, data reception (e.g., system Information Block (SIB) 1, msg 2/4/B of a Random Access Channel (RACH) procedure, etc.) prior to a Radio Resource Control (RRC) connection may not benefit from TRS-based fine timing error correction.

Timing resolution may be insufficient when the data subcarrier spacing (SCS) is much larger than SSB SCS before the TRS configuration is signaled (e.g., via RRC configuration), which may cause some performance degradation. This is because a larger SCS corresponds to a shorter symbol duration. Further, in systems for reducing TRS overhead, such as a multiple transmission reception point (mTRP) scenario, some type of Reference Signal (RS) with a relatively large pull-in range may be required to refine the timing estimate when the TRS is not transmitted (or when relatively few TRSs are transmitted).

Accordingly, certain aspects of the present disclosure provide techniques for frequency tracking and timing tracking using wideband RS. The techniques proposed herein may result in less frequent TRS transmissions and thus reduced TRS overhead.

When connected to and communicating with a wireless communication network, such as wireless communication system 100, a User Equipment (UE) may need to perform one or more synchronization procedures with the wireless communication network to correct timing errors to allow the UE to properly receive transmissions from the wireless communication network. In particular, certain aspects provide techniques for frequency tracking and timing tracking using a wideband Reference Signal (RS).

Fig. 4 shows a time-frequency resource grid 400 illustrating resource allocation to TRSs. As shown, time (in the form of symbols) is plotted along the horizontal axis, while frequency (in the form of subcarriers) is plotted along the vertical axis. The time-frequency resource grid 400 illustrated in fig. 4 may represent one Resource Block (RB) comprising 12 subcarriers and one slot (e.g., comprising 12 to 14 symbols per slot), as described with respect to fig. 3A. As shown, in this example, the time-frequency resource grid 400 includes resources for Physical Downlink Control Channel (PDCCH) transmissions, physical Downlink Shared Channel (PDSCH) transmissions, and TRSs.

The TRS is a special type of channel state information reference signal (CSI-RS). For example, the TRS may include a set of resources with a plurality of periodic CRS-RSs. In a typical configuration, the TRS may be transmitted in two adjacent slots and within two symbols within each slot. For example, as illustrated in fig. 4, TRSs may be transmitted within symbols 4 and 8 of a time-frequency resource grid 400, the time-frequency grid 400 having a symbol interval of 4 (Δn _TRS =4). Further, as depicted, the TRS may have a subcarrier spacing (SCS) of four subcarriers (e.g., ak) measured from the center of each TRS RE _TRS =4), resulting in a TRS density within a resource block (e.g., comprising only 12 subcarriers) of three resource elements. In other words, as depicted in FIG. 4, due to Δk _TRS =4, three TRSs may be transmitted within a resource block.

In addition, the TRS may transmit data in time slots (Δn _TRS ) Symbol intervals (e.g., an _TRS =4 symbols). In some cases, the symbol positions for the TRSs may be configured by Radio Resource Control (RRC) signaling and may be one of several options. For example, as shown in fig. 4, the TRSs may be located in symbols 4 and 8. In other cases, the TRS may be located in symbols 5 and 9. In yet other cases, the TRS may be located in symbols 6 and 10.

In general, if the timing error is within the pull-in range of the TRS symbol, the timing error may be corrected only by the TRS. The timing pull-in range may be based on the SCS of the PDSCH and specify a maximum amount of timing error (e.g., typically in microseconds) that may be corrected. In other words, any timing error that is greater than the timing pull-in range of the TRS may not be corrected by using the TRS. As an example, the TRS timing pull-in range may be determined according to the following equation 1.

As shown in formula 1, Δk _TRS Is the subcarrier spacing of the TRS, and SCS _PDSCH Is the subcarrier spacing of PDSCH. In using Deltak _TRS In a legacy system with subcarrier spacing of=4, equation 1 may be simplified as in equation 2 below.

In some cases, whether the timing error is within the timing pull-in range of the TRS and thus correctable by the TRS may depend on the magnitude of the timing error after SSB timing correction has been performed. In other words, whether the timing error is within the pull-in range of the TRS may depend on the SSB configuration. For example, in the current SSB configuration, the synchronization signal of the SSB may include 127 subcarriers (k _SSB =127) and has a granularity or resolution determined according to the following equation 3.

As depicted, BW _SSB Is the bandwidth associated with the SSB and may be based on the number of subcarriers (e.g., k _SSB ) And subcarrier spacing (SCS _SSB ). In some cases, the granularity of SSB may be enhanced using 2-fold oversampling, which is represented in equation 4 below.

Accordingly, as an example, assuming that the number of subcarriers associated with SSB is 127 subcarriers and assuming a subcarrier spacing of 120kHz, the SSB granularity may be about 32.81 nanoseconds (ns), as shown below in equation 5.

In the example shown in equation 5, the SSB granularity of 32.81ns may represent the minimum amount of timing error that can be corrected. Accordingly, as can be seen, as the SSB subcarrier spacing increases, the SSB granularity or the minimum amount of timing error that can be corrected becomes smaller. Typically, it is preferable to have a lower SSB granularity, as this will allow SSBs to correct finer timing errors.

In some cases, the amount of timing error that can be corrected using SSB may be determined in different ways. The first approach may be based on the number of samples n. For example, in such a case, assuming that SSB can reduce timing error to six samples (n=6 samples), the timing error after SSB correction can be at n×g _SSB Within a range of = 196.86 ns.

Another way of determining the amount of timing error that can be corrected by the SSB may be based on a cyclic prefix (CP _SSB ). For example, SSBs can typically reduce timing errors toWithin the inner part. In such a case, it is assumed that a subcarrier spacing (SCS _SSB =120 kHz) and a cyclic prefix of 585.94ns (CP _SSB = 585.94 ns), the timing error after SSB correction may be around 292.97 ns. For example, the symbol time of each SSB symbol (without CP) may be equal to +.>Typically, the CP occupies 0.0703125 of the symbol time. Thus, for SCS _SSB ＝120kHz，/> In some cases, additional security margins may be required to account for timing errors due to noise. For example, as noise increases, SSB-based timing error correction algorithms may not be able to reduce timing error to 6 samples or +.>The timing error correction algorithm may be able to reduce the timing error to 7 or 8 samples, or slightly exceed +.>Thus, a completely new margin of security may be required to ensure that the time pull-in range of the TRS can be corrected for +.>Or 6 samples slightly more. However, there are still problems with enhancement of TRS for RRC idle/inactive mode operation.

Aspects relating to frequency tracking and timing tracking using wideband RS

As mentioned above, when the data subcarrier spacing (SCS) is much larger than SSB SCS before the TRS configuration is signaled (e.g., via RRC configuration), the timing resolution may be insufficient, which may cause some performance degradation. Furthermore, in some cases, it may be beneficial to reduce TRS overhead by sending fewer TRS signals, especially for multi-transmit receive point (mTRP) operations. If fewer TRSs are sent (when TRS signals are not transmitted (or relatively fewer TRS signals are transmitted), then alternative Reference Signals (RSs) with relatively large pull-in ranges may be used to refine the timing estimate.

Aspects of the present disclosure provide apparatuses, methods, processing systems, and computer-readable media for frequency tracking, timing tracking, or both frequency and time tracking by a User Equipment (UE) using a wideband Reference Signal (RS). An example of such a wideband RS is a wideband DMRS transmitted using a wideband precoder.

The techniques presented herein may help reduce TRS overhead by utilizing wideband DMRS. As described in more detail below, wideband DMRS may be opportunistically scheduled, for example, when one or more conditions are met (e.g., when the UE has not been configured with a TRS or is configured with only sparse TRSs).

Fig. 5 is a flowchart illustrating example operations 500 for wireless communication in accordance with certain aspects of the present disclosure. The operations 500 may be performed, for example, by a UE (e.g., the UE 104 in the wireless communication network 100 of fig. 1) to perform frequency tracking and timing tracking using wideband RSs. The operations 500 may be implemented as software components executing and running on one or more processors (e.g., the controller/processor 280 of fig. 2). Further, the signal transmission and reception by the UE in operation 500 may be implemented, for example, by one or more antennas (e.g., antenna 252 of fig. 2). In certain aspects, signaling and/or reception by the UE may be achieved via a bus interface of one or more processors (e.g., controller/processor 280, including tracking component 281) to obtain and/or output signals.

The operations 500 begin in block 510 by monitoring a wideband Reference Signal (RS) from a network entity that occupies a frequency resource that is wider than a Tracking Reference Signal (TRS) transmitted by the network entity when one or more conditions are met.

At 520, at least one of frequency tracking or timing tracking is performed based on the monitoring.

Fig. 6 is a flow chart illustrating example operations 600 for wireless communication, which may be considered complementary to the operations 500 of fig. 5. For example, operation 600 may be performed by a BS (e.g., BS102 in wireless communication system 100 of fig. 1) to transmit a wideband RS to a UE performing operation 500 of fig. 5. The operations 600 may be implemented as software components executing and running on one or more processors (e.g., the controller/processor 240 of fig. 2). Operation 600 may be complementary to operation 500 performed by the UE. Further, signal transmission and reception by the BS in operation 600 may be implemented, for example, by one or more antennas (e.g., antenna 234 of fig. 2). In certain aspects, signaling and/or reception by the BS may be achieved via a bus interface of one or more processors (e.g., controller/processor 240, including tracking component 241) to obtain and/or output signals.

Operation 600 begins at 610 when one or more conditions are met to trigger (e.g., to a UE) transmission of a wideband Reference Signal (RS) that occupies a frequency resource that is wider than a Tracking Reference Signal (TRS) transmitted by the network entity. At 620, the network entity transmits a wideband RS to the UE based on the detection.

Operations 500 and 600 of fig. 5 and 6 may be understood with reference to call flow diagram 700 of fig. 7, fig. 7 illustrating signaling between a network entity and a UE based on wideband RS performing time and/or frequency tracking.

As shown, at 702, the ue determines whether one or more conditions are met to cause a network entity to transmit a wideband RS. When these conditions are met, the ue monitors the wideband RS at 704. Based on the wideband RS 706, the ue performs frequency tracking and/or time tracking.

In some cases, one of these conditions may be a Radio Resource Control (RRC) configuration in which the UE 104 has not received a Tracking Reference Signal (TRS). In this case, a wideband RS (such as a wideband DMRS) may assist the UE in performing initial access, e.g., to refine the ability of the relatively coarse SSB-based timing using the wideband DMRS.

In some cases, one of these conditions may be that the Synchronization Signal Block (SSB) subcarrier spacing (SCS) is smaller than the Physical Downlink Shared Channel (PDSCH) SCS. This may be implemented as a rule such that the wideband precoder for a DMRS is used whenever:

SCS _SSB <SCS _DATA x m (i.e., the data SCS multiplied by the integer m),

where m is an integer, m > =2. On the other hand, when the ratio between SSB and data SCS is relatively small (e.g., and this rule is not satisfied), SSB time estimation may be assumed to be good enough.

In some cases, the network may indicate via System Information (SI) that wideband DMRS is to be used for the upcoming transmission. For example, the network may indicate the use of a wideband DMRS via Remaining Minimum System Information (RMSI).

In some cases, the BS may transmit an RRC configuration indicating the wideband precoder to the UE and then indicate the use of the wideband precoder via a Downlink Control Information (DCI) message that schedules subsequent transmissions. The BS may then transmit a subsequent transmission with the wideband DMRS using the wideband precoder.

In some cases, the UE may provide an indication that the UE supports Timing Offset Compensation (TOC) using wideband DMRS. For example, the indication may be provided as part of a UE capability report, as shown in fig. 7. BS102 may configure fewer TRS transmissions for UEs that indicate such capabilities, and instead, these UEs may be scheduled with a wideband DMRS. In other words, BS102 can configure UEs supporting TOCs using wideband DMRS to have TRS transmissions (e.g., zero or fewer TRS transmissions) that are more sparse in time than UEs not supporting TOCs using wideband DMRS. As such, BS102 may configure a first set of one or more UEs that indicate TOC supporting use of wideband DMRS to have fewer TRS transmissions than configured for a second set of one or more UEs.

In some cases, after the RRC configuration indicates TRS configuration, the BS (e.g., the gNB) still configures the wideband DMRS for time refinement to reduce TRS overhead. This mixing between wideband DMRS and TRS will help reduce TRS overhead and UE complexity.

In some cases, DMRS bundling may be used with wideband DMRS, which may increase the accuracy of UE tracking based on wideband DMRS. DMRS bundling generally refers to transmitting the same or coherent DMRS in multiple slots to achieve coverage enhancement. This may allow the UE to perform joint channel estimation on DMRSs in multiple slots to improve accuracy.

In some cases, a wideband DMRS may be used in a scenario with multiple Transmission Reception Points (TRPs). Each TRP may be associated with a different Transmission Configuration Indicator (TCI) state (e.g., QCL/transmission parameters indicating the TRP).

In some cases, the scheduling DCI may indicate a plurality of TCI states and indicate one bundle size. However, in some cases, different bundling sizes may be supported by each TCI state to allow wideband DMRS-based timing refinement and to enable reduction of TRS overhead.

Different bundle sizes may be indicated in different ways. In some cases, the bundling size in the DCI may be applied to one TCI state (e.g., a first TCI) and another bundling size (e.g., defined by RRC or Medium Access Control (MAC) Control Element (CE) signaling) may be applied to another TCI state.

In some cases, the signaled bundle size may be applied to the first TCI state and the bundle size of another TCI may be determined based on the TRS transmission. For example, a time duration threshold may be configured, and if the time duration between the last TRS and the data transmission is greater than the time duration threshold, a wideband DMRS may be assumed. Otherwise, the signaled bundle size may be applied to both TCI states.

As another example, a network entity may configure a TRS with one TCI state having a larger duty cycle/period (relatively infrequent TRS transmissions) than another TCI state. The DMRS of the TCI may be assumed to be wideband precoded whenever this duty cycle is greater than a configured threshold. In some cases, the bundle size field in the DCI may be increased such that the gNB may signal a different bundle size for each individual TCI state.

In some aspects, different TCI states may have different prb-bundlegtype (pre-bundling type) configurations. For example, one TCI state may be configured with "dynamic bundling" and another TCI state may be configured with "static bundling". In some cases, TCI states with more frequent TRSs may be configured with "static bundling" and TCI states with less frequent TRSs may be configured with "dynamic bundling. In certain aspects, a Physical Resource Block (PRB) bundling size field in DCI may be applied to a TCI state with a "dynamic bundling" configuration.

In certain aspects, a bundle size field may be maintained (e.g., as defined in the current NR wireless standard), but this field may point to a bundle size vector corresponding to multiple TCI states. For example, in the current system, when a PRB bundle size indicator (P _BWP.i ) When set to 0, the UE uses the data from the second group P _BWP.i P of' value _BWP.i 'value'. However, the pbwp.i' values of the second group may be configured differently for different TCI states. For example, the second group of one TCI state may be configured with "4" PRBs, while the other TCI state may be configured with "wideband" PRBs. In this way, when the PRB bundle size indicator is set to 0, it may signal different bundle sizes for different TCI states.The same applies to the first group P _BWP.i And (5) configuration.

In certain aspects, to allow joint processing of DMRS and TRSs, the beams for DMRS and TRS transmissions may be quasi-co-located (QCL). In this regard, this joint processing of DMRS and TRS may be used to refine the frequency offset estimate. In some cases, the network entity may indicate to the UE whether the same precoder is used for the TRS and DMRS signals. This indication may be via RRC signaling, MAC-CD or DCI. In some cases, if indicated, the UE may assume that the same precoder is applied to the DMRS and the TRS if the DMRS and the TRS are transmitted within a specified time window.

Example Wireless communication device

Fig. 8 depicts an example communication device 800 including various components operable, configured, or adapted to perform operations for the techniques disclosed herein, such as the operations depicted and described with reference to fig. 5. In some examples, the communication device 800 may be a user equipment 104, as described, for example, with reference to fig. 1 and 2.

The communication device 800 includes a processing system 808 that is coupled to a transceiver 802 (e.g., a transmitter and/or receiver). The transceiver 808 is configured to transmit (or send) and receive signals (such as the various signals described herein) for the communication device 800 via the antenna 810. The processing system 802 may be configured to perform processing functions for the communication device 800, including processing signals received and/or to be transmitted by the communication device 800.

The processing system 802 includes one or more processors 820 coupled to a computer-readable medium/memory 830 via a bus 806. In certain aspects, the computer-readable medium/memory 830 is configured to store instructions (e.g., computer-executable code) that, when executed by the one or more processors 820, cause the one or more processors 820 to perform the operations illustrated in fig. 5, or other operations for performing the various techniques for frequency tracking and timing tracking using wideband RS discussed herein.

In the depicted example, computer readable medium/memory 830 stores code 831 for monitoring and code 832 for execution.

In the depicted example, the one or more processors 820 include circuitry configured to implement code stored in the computer-readable medium/memory 830, including circuitry 821 for monitoring and circuitry 822 for executing.

The various components of the communication device 800 may provide means for performing the methods described herein (including with respect to fig. 5).

In some examples, the means for transmitting or sending (or means for outputting for transmission) may include the transceiver 254 and/or antenna(s) 252 of the user equipment 104 illustrated in fig. 2 and/or the transceiver 810 and antenna 810 of the communication device 800 in fig. 8.

In some examples, the means for receiving (or means for obtaining) may include the transceiver 254 and/or antenna(s) 252 of the user equipment 104 illustrated in fig. 2 and/or the transceiver 808 and antenna 810 of the communication device 800 in fig. 8.

In some examples, the means for determining, the means for monitoring, and the means for executing may include various processing system components, such as: one or more processors 820 in fig. 8, or aspects of user equipment 104 depicted in fig. 2, include a receive processor 258, a transmit processor 264, a TX MIMO processor 266, and/or a controller/processor 280 (including a tracking component 281).

It is noted that fig. 8 is merely an example of use, and that many other examples and configurations of communication device 800 are possible.

Fig. 9 depicts an example communication device 900 including various components operable, configured, or adapted to perform operations for the techniques disclosed herein, such as the operations depicted and described with respect to fig. 6. In some examples, communication device 900 may be a base station 102, such as base station 102 described with reference to fig. 1 and 2.

The communication device 900 includes a processing system 902 coupled to a transceiver 908 (e.g., a transmitter and/or receiver). The transceiver 908 is configured to transmit (or send) and receive signals (such as the various signals described herein) for the communication device 900 via the antenna 910. The processing system 902 may be configured to perform processing functions for the communication device 900, including processing signals received and/or to be transmitted by the communication device 900.

The processing system 902 includes one or more processors 920 coupled to a computer-readable medium/memory 930 via a bus 906. In certain aspects, the computer-readable medium/memory 930 is configured to store instructions (e.g., computer-executable code) that, when executed by the one or more processors 920, cause the one or more processors 920 to perform the operations illustrated in fig. 6, or other operations for performing the various techniques for frequency tracking and timing tracking using wideband RS discussed herein.

In the depicted example, computer-readable medium/memory 930 stores code 931 for detecting and code 932 for transmitting.

In the depicted example, the one or more processors 920 include circuitry configured to implement code stored in a computer-readable medium/memory 930, including circuitry 921 for detection and circuitry 922 for transmission.

The various components of the communication device 900 may provide means for performing the methods described herein (including with respect to fig. 6).

In some examples, the means for transmitting or sending (or means for outputting for transmission) may include the transceiver 232 and/or antenna(s) 234 of the base station 102 illustrated in fig. 2 and/or the transceiver 908 and antenna 910 of the communication device 900 in fig. 9.

In some examples, the means for receiving (or means for obtaining) may include the transceiver 232 and/or the antenna(s) 234 of the base station illustrated in fig. 2 and/or the transceiver 908 and antenna 910 of the communication device 900 in fig. 9.

In some examples, the means for determining, the means for providing, and the means for restricting may include various processing system components, such as: one or more processors 920 in fig. 9, or aspects of base station 102 depicted in fig. 2, include a receive processor 238, a transmit processor 220, a TX MIMO processor 230, and/or a controller/processor 240 (including a tracking component 241).

It is noted that fig. 9 is merely an example of use, and that many other examples and configurations of communication device 900 are possible.

Example aspects

Examples of implementations are described in the following numbered aspects:

aspect 1: a method for wireless communication by a User Equipment (UE), comprising: monitoring a wideband Reference Signal (RS) from a network entity when one or more conditions are met, the wideband RS occupying a frequency resource that is wider than a Tracking Reference Signal (TRS) transmitted by the network entity; and performing at least one of frequency tracking or timing tracking based on the monitoring.

Aspect 2: the method of aspect 1, wherein the wideband RS comprises a wideband demodulation reference signal (DMRS) transmitted from the network entity using a wideband precoder.

Aspect 3: the method of aspect 2, wherein the one or more conditions include a Radio Resource Control (RRC) configuration of the TRS that the UE has not received.

Aspect 4: the method of aspect 3, wherein the one or more conditions further comprise a Synchronization Signal Block (SSB) subcarrier spacing (SCS) that is less than a Physical Downlink Shared Channel (PDSCH) SCS.

Aspect 5: the method of any of aspects 3-4, wherein the one or more conditions further include the UE receiving System Information (SI) indicating that the UE is to perform at least one of frequency tracking or timing tracking on an upcoming transmission using a wideband DMRS.

Aspect 6: the method of any of aspects 3-5, further comprising: receiving an RRC configuration indicating the wideband precoder; receiving a Downlink Control Information (DCI) message scheduling a subsequent transmission; and receiving the subsequent transmission, wherein the subsequent transmission is transmitted by the network with the wideband DMRS using the wideband precoder.

Aspect 7: the method of any of aspects 2-6, wherein at least one of the conditions is that the UE has provided an indication that the UE supports Timing Offset Compensation (TOC) using wideband DMRS.

Aspect 8: the method of aspect 7, further comprising receiving signaling to the UE to perform time refinement based on the wideband DMRS as an alternative or in addition to the TRS after Radio Resource Control (RRC) configuration.

Aspect 9: the method of any of aspects 2-8, further comprising: receiving Downlink Control Information (DCI) indicating at least two Transmission Configuration Indicator (TCI) states; and applying different bundling sizes for transmissions using the at least two TCI states.

Aspect 10: the method of aspect 9, wherein applying different bundling sizes for transmissions using the at least two TCI states comprises: applying a first bundling size indicated in the DCI for a transmission using a first TCI state; and applying a second bundling size indicated via at least one of Radio Resource Control (RRC) or Medium Access Control (MAC) Control Element (CE) signaling to a transmission using the second TCI state.

Aspect 11: the method of any of aspects 9-10, wherein applying different bundling sizes for transmissions using the at least two TCI states comprises: applying a first bundling size indicated in the DCI for a transmission using a first TCI state; and applying a second bundling size derived from the TRS transmission to the transmission using the second TCI state.

Aspect 12: the method of any of aspects 9-11, wherein applying different bundling sizes for transmissions using the at least two TCI states comprises: applying a first bundling size indicated in the DCI for a transmission using a first TCI state; and applying a second bundling size also indicated in the DCI for a transmission using a second TCI state.

Aspect 13: the method of any of aspects 9-12, wherein the different bundle sizes are configured for the at least two TCI states.

Aspect 14: the method of any of aspects 9-13, wherein the different bundle sizes are determined based on a field in the DCI mapped to a bundle size vector for the at least two TCI states.

Aspect 15: the method of any one of aspects 2-14, further comprising: monitoring the TRS with one or more beams quasi co-located (QCL) with one or more beams for monitoring the wideband DMRS; and jointly processing the DMRS and TRS to perform at least one of frequency tracking or timing tracking.

Aspect 16: the method of aspect 15, wherein the joint processing is performed to refine the frequency offset estimate.

Aspect 17: the method of any of aspects 2-16, further comprising receiving an indication of whether the same precoder is used for the DMRS and the TRS.

Aspect 18: the method of aspect 17, wherein the indication is received via at least one of Radio Resource Control (RRC) signaling, medium Access Control (MAC) Control Elements (CEs), or Downlink Control Information (DCI) signaling.

Aspect 19: a User Equipment (UE), comprising: a memory; a transceiver; and at least one processor coupled to the memory and the transceiver, the at least one processor configured to perform the method of any of aspects 1-18.

Aspect 20: a method for wireless communication by a network entity, comprising: detecting when one or more conditions are met to transmit a wideband Reference Signal (RS) to a User Equipment (UE), the wideband RS occupying frequency resources that are wider than a Tracking Reference Signal (TRS) transmitted by the network entity; and transmitting the wideband RS to the UE based on the detecting.

Aspect 21: the method of aspect 20, wherein the wideband RS comprises a wideband demodulation reference signal (DMRS) transmitted from the network entity using a wideband precoder.

Aspect 22: the method of aspect 21, wherein the one or more conditions include a Radio Resource Control (RRC) configuration of the TRS that the UE has not received.

Aspect 23: the method of aspect 22, wherein the one or more conditions further comprise a Synchronization Signal Block (SSB) subcarrier spacing (SCS) that is less than a Physical Downlink Shared Channel (PDSCH) SCS.

Aspect 24: the method of any of aspects 22-23, wherein the one or more conditions further comprise the UE receiving System Information (SI) indicating that the UE is to perform at least one of frequency tracking or timing tracking on an upcoming transmission using a wideband DMRS.

Aspect 25: the method of any of aspects 22-24, further comprising: transmitting an RRC configuration indicating the wideband precoder to the UE; transmitting a Downlink Control Information (DCI) message scheduling a subsequent transmission; and transmitting the subsequent transmission with the wideband DMRS using the wideband precoder.

Aspect 26: the method of any of aspects 21-25, wherein at least one of the conditions is that the UE has provided an indication that the UE supports Timing Offset Compensation (TOC) using wideband DMRS.

Aspect 27: the method of aspect 26, further comprising transmitting signaling to the UE to perform time refinement based on the wideband DMRS as an alternative or in addition to the TRS after Radio Resource Control (RRC) configuration.

Aspect 28: the method of any of aspects 21-27, further comprising: downlink Control Information (DCI) indicating at least two Transmission Configuration Indicator (TCI) states associated with different bundling sizes for a UE to apply to bundled transmissions is transmitted.

Aspect 29: the method of aspect 28, wherein the different bundle sizes include: a first bundling size indicated in the DCI for a transmission using a first TCI state; and a second bundling size for transmissions using a second TCI state indicated via at least one of Radio Resource Control (RRC) or Medium Access Control (MAC) Control Element (CE) signaling.

Aspect 30: the method of any of aspects 28-29, wherein the different bundle sizes include: a first bundling size indicated in the DCI for a transmission using a first TCI state; and a second bundling size derived from the TRS transmission for transmissions using the second TCI state.

Aspect 31: the method of any of aspects 28-30, wherein the different bundle sizes include: a first bundling size indicated in the DCI for a transmission using a first TCI state; and a second bundling size for transmissions using the second TCI state also indicated in the DCI.

Aspect 32: the method of any of aspects 28-31, wherein the different bundle sizes are configured for the at least two TCI states.

Aspect 33: the method of any of aspects 28-32, wherein the different bundle sizes are determined based on a field in the DCI mapped to a bundle size vector for the at least two TCI states.

Aspect 34: the method of any of aspects 21-33, further comprising: the TRS is transmitted to the UE, wherein the network entity transmits the DMRS and TRS with quasi-co-located (QCL) beams.

Aspect 35: the method of aspect 34, further comprising transmitting an indication to the UE as to whether the same precoder is used for the DMRS and TRS.

Aspect 36: the method of aspect 35, wherein the indication is transmitted via at least one of Radio Resource Control (RRC), medium Access Control (MAC) Control Element (CE), or Downlink Control Information (DCI) signaling.

Aspect 37: a network entity, comprising: a memory; and at least one processor coupled to the memory, the at least one processor configured to perform the method of any of aspects 20-36.

Additional wireless communication network considerations

The techniques and methods described herein may be used for various wireless communication networks (or Wireless Wide Area Networks (WWANs)) and Radio Access Technologies (RATs). Although aspects may be described herein using terms commonly associated with 3G, 4G, and/or 5G (e.g., 5G New Radio (NR)) wireless technologies, aspects of the present disclosure may be equally applicable to other communication systems and standards not explicitly mentioned herein.

The 5G wireless communication network may support various advanced wireless communication services, such as enhanced mobile broadband (emmbb), millimeter wave (mmWave), machine Type Communication (MTC), and/or ultra-reliable, low latency communication for mission critical (URLLC). These services and other services may include latency and reliability requirements.

Returning to fig. 1, various aspects of the present disclosure may be performed within an example wireless communication network 100.

In 3GPP, the term "cell" can refer to a coverage area of a NodeB and/or a narrowband subsystem serving the coverage area, depending on the context in which the term is used. In an NR system, the terms "cell" and BS, next generation node BS (gNB or gndeb), access Points (APs), distributed Units (DUs), carriers, or transmission/reception points may be used interchangeably. The BS may provide communication coverage for macro cells, pico cells, femto cells, and/or other types of cells.

A macro cell may generally cover a relatively large geographic area (e.g., several kilometers in radius) and may allow unrestricted access by UEs with service subscription. A picocell may cover a relatively small geographic area (e.g., a stadium) and may allow unrestricted access by UEs with service subscription. A femtocell may cover a relatively small geographic area (e.g., a residence) and may allow restricted access by UEs associated with the femtocell (e.g., UEs in a Closed Subscriber Group (CSG) and UEs of users in the residence). The BS for a macro cell may be referred to as a macro BS. The BS for a pico cell may be referred to as a pico BS. The BS for a femto cell may be referred to as a femto BS, a home BS, or a home NodeB.

A base station 102 configured for 4G LTE, collectively referred to as an evolved Universal Mobile Telecommunications System (UMTS) terrestrial radio access network (E-UTRAN), may interface with the EPC 160 through a first backhaul link 132 (e.g., an S1 interface). A base station 102 configured for 5G (e.g., 5G NR or next generation RAN (NG-RAN)) may interface with the 5gc 190 over the second backhaul link 184. Base stations 102 may communicate with each other directly or indirectly (e.g., through EPC 160 or 5gc 190) over a third backhaul link 134 (e.g., an X2 interface). The third backhaul link 134 may be generally wired or wireless.

The small cell 102' may operate in licensed and/or unlicensed spectrum. When operating in unlicensed spectrum, the small cell 102' may employ NR and use the same 5GHz unlicensed spectrum as that used by the Wi-Fi AP 150. Small cells 102' employing NR in the unlicensed spectrum may push up access network coverage and/or increase access network capacity.

Some base stations, such as the gNB 180, may operate in the legacy sub-6 GHz spectrum, millimeter wave (mmWave) frequencies, and/or near mmWave frequencies to be in communication with the UE 104. When the gNB 180 operates in mmWave or near mmWave frequencies, the gNB 180 may be referred to as a mmWave base station.

The communication link 120 between the base station 102 and, for example, the UE 104 may be over one or more carriers. For example, for each carrier allocated in carrier aggregation up to yxmhz (x component carriers) in total for transmission in each direction, base station 102 and UE 104 may use a spectrum up to Y MHz (e.g., 5, 10, 15, 20, 100, 400MHz, and other MHz) bandwidth. These carriers may or may not be contiguous with each other. The allocation of carriers may be asymmetric with respect to DL and UL (e.g., more or fewer carriers may be allocated to DL than UL). The component carriers may include a primary component carrier and one or more secondary component carriers. The primary component carrier may be referred to as a primary cell (PCell) and the secondary component carrier may be referred to as a secondary cell (SCell).

The wireless communication system 100 further includes a Wi-Fi Access Point (AP) 150 in communication with Wi-Fi Stations (STAs) 152 via a communication link 154 in, for example, a 2.4GHz and/or 5GHz unlicensed spectrum. When communicating in the unlicensed spectrum, the STA 152/AP 150 may perform a Clear Channel Assessment (CCA) prior to communication to determine whether the channel is available.

Some UEs 104 may communicate with each other using a device-to-device (D2D) communication link 158. The D2D communication link 158 may use the DL/UL WWAN spectrum. The D2D communication link 158 may use one or more side link channels such as a physical side link broadcast channel (PSBCH), a physical side link discovery channel (PSDCH), a physical side link shared channel (PSSCH), and a physical side link control channel (PSCCH). D2D communication may be through a variety of wireless D2D communication systems such as, for example, flashLinQ, wiMedia, bluetooth, zigBee, wi-Fi based on the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard, 4G (e.g., LTE), or 5G (e.g., NR), just to name a few options.

EPC 160 may include a Mobility Management Entity (MME) 162, other MMEs 164, a serving gateway 166, a Multimedia Broadcast Multicast Service (MBMS) gateway 168, a broadcast multicast service center (BM-SC) 170, and a Packet Data Network (PDN) gateway 172.MME 162 may be in communication with a Home Subscriber Server (HSS) 174. The MME 162 is a control node that handles signaling between the UE 104 and the EPC 160. Generally, MME 162 provides bearer and connection management.

In general, user Internet Protocol (IP) packets are communicated through the serving gateway 166, with the serving gateway 166 itself being connected to the PDN gateway 172. The PDN gateway 172 provides UE IP address allocation as well as other functions. The PDN gateway 172 and BM-SC 170 are connected to IP services 176, which IP services 176 may include, for example, the internet, intranets, IP Multimedia Subsystem (IMS), packet Switched (PS) streaming services, and/or other IP services.

The BM-SC 170 may provide functionality for MBMS user service provisioning and delivery. The BM-SC 170 may be used as an entry point for content provider MBMS transmissions, may be used to authorize and initiate MBMS bearer services within a Public Land Mobile Network (PLMN), and may be used to schedule MBMS transmissions. The MBMS gateway 168 may be used to distribute MBMS traffic to base stations 102 belonging to a Multicast Broadcast Single Frequency Network (MBSFN) area broadcasting a particular service and may be responsible for session management (start/stop) and for collecting eMBMS related charging information.

The 5gc 190 may include access and mobility management functions (AMFs) 192, other AMFs 193, session Management Functions (SMFs) 194, and User Plane Functions (UPFs) 195. The AMF 192 may be in communication with a Unified Data Management (UDM) 196.

The AMF 192 is typically a control node that handles signaling between the UE 104 and the 5gc 190. In general, AMF 192 provides QoS flows and session management.

All user Internet Protocol (IP) packets are transported through the UPF 195, the UPF 195 being connected to the IP service 197 and providing UE IP address assignment and other functions for the 5gc 190. The IP services 197 may include, for example, the internet, an intranet, an IP Multimedia Subsystem (IMS), PS streaming services, and/or other IP services.

Returning to fig. 2, various example components of BS102 and UE 104 (e.g., wireless communication network 100 of fig. 1) that may be used to implement aspects of the disclosure are depicted.

At BS102, transmit processor 220 may receive data from data source 212 and control information from controller/processor 240. The control information may be for a Physical Broadcast Channel (PBCH), a Physical Control Format Indicator Channel (PCFICH), a physical hybrid ARQ indicator channel (PHICH), a Physical Downlink Control Channel (PDCCH), a group common PDCCH (GC PDCCH), and others. In some examples, the data may be for a Physical Downlink Shared Channel (PDSCH).

A Medium Access Control (MAC) -control element (MAC-CE) is a MAC layer communication structure that may be used for control command exchange between wireless nodes. The MAC-CE may be carried in a shared channel, such as a Physical Downlink Shared Channel (PDSCH), a Physical Uplink Shared Channel (PUSCH), or a physical side link shared channel (PSSCH).

Processor 220 may process (e.g., encode and symbol map) the data and control information to obtain data symbols and control symbols, respectively. The transmit processor 220 may also generate reference symbols, such as for a Primary Synchronization Signal (PSS), a Secondary Synchronization Signal (SSS), a PBCH demodulation reference signal (DMRS), and a channel state information reference signal (CSI-RS).

A Transmit (TX) multiple-input multiple-output (MIMO) processor 230 may perform spatial processing (e.g., precoding) on the data symbols, the control symbols, and/or the reference symbols, if applicable, and may provide output symbol streams to Modulators (MODs) 232a-232t in the transceiver. Each modulator 232a-232t in the transceiver may process a respective output symbol stream (e.g., for OFDM) to obtain an output sample stream. Each modulator may further process (e.g., convert to analog, amplify, filter, and upconvert) the output sample stream to obtain a downlink signal. Downlink signals from modulators 232a-232t in the transceivers may be transmitted via antennas 234a-234t, respectively.

At the UE 104, antennas 252a-252r may receive the downlink signals from the BS102 and may provide received signals to demodulators (DEMODs) 254a-254r, respectively, in a transceiver. Each demodulator 254a-254r in the transceiver may condition (e.g., filter, amplify, downconvert, and digitize) a respective received signal to obtain input samples. Each demodulator may further process the input samples (e.g., for OFDM) to obtain received symbols.

MIMO detector 256 may obtain received symbols from all of the demodulators 254a-254r in the transceiver, perform MIMO detection on the received symbols if applicable, and provide detected symbols. A receive processor 258 may process (e.g., demodulate, deinterleave, and decode) the detected symbols, provide decoded data to the UE 104 to a data sink 260, and provide decoded control information to a controller/processor 280.

On the uplink, at the UE 104, a transmit processor 264 may receive and process data from a data source 262 (e.g., for a Physical Uplink Shared Channel (PUSCH)) and control information from a controller/processor 280 (e.g., for a Physical Uplink Control Channel (PUCCH)). The transmit processor 264 may also generate reference symbols for a reference signal, e.g., a Sounding Reference Signal (SRS). The symbols from transmit processor 264 may be precoded by a TX MIMO processor 266 if applicable, further processed by modulators 254a-254r in the transceiver (e.g., for SC-FDM), and transmitted to BS102.

At BS102, uplink signals from UEs 104 may be received by antennas 234a-t, processed by demodulators 232a-232t in a transceiver, detected by a MIMO detector 236 if applicable, and further processed by a receive processor 238 to obtain decoded data and control information sent by UEs 104. The receive processor 238 may provide the decoded data to a data sink 239 and the decoded control information to a controller/processor 240.

Memories 242 and 282 may store data and program codes for BS102 and UE 104, respectively. The one or more processors (e.g., processors 220, 230, 238, and 240) of BS102 are coupled to memory 242, and the one or more processors of BS102 may be configured to cause BS102 (which may also be referred to as a network entity) to perform the methods described herein, such as, for example, the methods discussed with reference to fig. 6 and 7. The one or more processors of the UE 104 are coupled to the memory 282 and the transceiver 254, and the one or more processors of the UE 104 (e.g., processors 258, 264, 266, and 280) may be configured to cause the UE 104 to perform the methods described herein, such as, for example, the methods discussed with reference to fig. 5 and 7. When receiving or transmitting various configurations, indications, messages, or data (e.g., RRC, DCI, and/or MAC-CE, reference signals, signaling, etc.), the UE 104 may receive or transmit such configurations, indications, messages, or data via the transceiver 254.

The scheduler 244 may schedule UEs for data transmission on the downlink and/or uplink.

The 5G may utilize Orthogonal Frequency Division Multiplexing (OFDM) with Cyclic Prefix (CP) on uplink and downlink. 5G may also support half duplex operation using Time Division Duplex (TDD). OFDM and single carrier frequency division multiplexing (SC-FDM) divide the system bandwidth into a plurality of orthogonal subcarriers, which are also commonly referred to as tones and bins. Each subcarrier may be modulated with data. The modulation symbols may be transmitted with OFDM in the frequency domain and SC-FDM in the time domain. The spacing between adjacent subcarriers may be fixed and the total number of subcarriers may depend on the system bandwidth. In some examples, the minimum resource allocation, referred to as a Resource Block (RB), may be 12 consecutive subcarriers. The system bandwidth may also be divided into sub-bands. For example, one subband may cover multiple RBs. NR may support a 15KHz base subcarrier spacing (SCS) and other SCSs may be defined relative to the base SCS (e.g., 30KHz, 60KHz, 120KHz, 240KHz, and others).

As described above, fig. 3A-3D depict various example aspects of a data structure for a wireless communication network, such as wireless communication network 100 of fig. 1.

In aspects, the 5G NR frame structure may be Frequency Division Duplex (FDD), where for a particular set of subcarriers (carrier system bandwidth), subframes within the set of subcarriers are dedicated to DL or UL. The 5G frame structure may also be Time Division Duplex (TDD), where for a particular set of subcarriers (carrier system bandwidth), the subframes within the set of subcarriers are dedicated to both DL and UL. In the example provided by fig. 3A and 3C, the 5G frame structure is assumed to be TDD, with subframe 4 configured with slot format 28 (mostly DL) and subframe 3 configured with slot format 34 (mostly UL), where D is DL, U is UL, and X is for flexible use between DL/UL. Although subframes 3, 4 are shown as having slot formats 34, 28, respectively, any particular subframe may be configured with any of a variety of available slot formats 0-61. The slot formats 0, 1 are full DL, full UL, respectively. Other slot formats 2-61 include a mix of DL, UL, and flexible symbols. The UE is configured with a slot format (dynamically configured by DL Control Information (DCI) or semi-statically/statically configured by Radio Resource Control (RRC) signaling) through a received Slot Format Indicator (SFI). Note that the following description also applies to a 5G frame structure that is TDD.

Other wireless communication technologies may have different frame structures and/or different channels. A frame (10 ms) may be divided into 10 equally sized subframes (1 ms). Each subframe may include one or more slots. The subframe may also include a mini slot, which may include 7, 4, or 2 symbols. In some examples, each slot may include 7 or 14 symbols, depending on the slot configuration.

For example, for slot configuration 0, each slot may include 14 symbols, and for slot configuration 1, each slot may include 7 symbols. The symbol on DL may be a Cyclic Prefix (CP) OFDM (CP-OFDM) symbol. The symbols on the UL may be CP-OFDM symbols (for high throughput scenarios) or Discrete Fourier Transform (DFT) -spread OFDM (DFT-s-OFDM) symbols (also known as single carrier frequency division multiple access (SC-FDMA) symbols) (for power limited scenarios; limited to single stream transmission).

The number of slots within a subframe is based on slot configuration and parameter design. For slot configuration 0, different parameter designs (μ) 0 through 5 allow 1, 2, 4, 8, 16, and 32 slots per subframe, respectively. For slot configuration 1, different parameter designs 0 through 2 allow 2, 4, and 8 slots per subframe, respectively. Accordingly, for slot configuration 0 and parameter design μ, there are 14 symbols per slot and 2 per subframe ^μ And each time slot. Subcarrier spacing and symbol length/duration are a function of parameter design. The subcarrier spacing may be equal to 2 ^μ ×15kHzWhere μ is the parameter design 0 to 5. Thus, parameter design μ=0 has a subcarrier spacing of 15kHz, while parameter design μ=5 has a subcarrier spacing of 480 kHz. The symbol length/duration is inversely related to the subcarrier spacing. Fig. 3A-3D provide examples of a slot configuration 0 having 14 symbols per slot and a parameter design μ=2 having 4 slots per subframe. The slot duration is 0.25ms, the subcarrier spacing is 60kHz, and the symbol duration is approximately 16.67 mus.

The resource grid may be used to represent a frame structure. Each slot includes Resource Blocks (RBs) (also referred to as Physical RBs (PRBs)) that extend for 12 consecutive subcarriers. The resource grid is divided into a plurality of Resource Elements (REs). The number of bits carried by each RE depends on the modulation scheme.

As illustrated in fig. 3A, some REs carry reference (pilot) signals (RSs) for UEs (e.g., UE 104 of fig. 1 and 2). The RS may comprise a demodulation RS (DM-RS) (indicated as R for one particular configuration) for channel estimation at the UE _x Where 100x is a port number, but other DM-RS configurations are possible) and a channel state information reference signal (CSI-RS). The RSs may also include beam measurement RSs (BRSs), beam Refinement RSs (BRRSs), and phase tracking RSs (PT-RSs).

Fig. 3B illustrates an example of various DL channels within a subframe of a frame. A Physical Downlink Control Channel (PDCCH) carries DCI within one or more Control Channel Elements (CCEs), each CCE including 9 RE groups (REGs), each REG including 4 consecutive REs in an OFDM symbol.

The Primary Synchronization Signal (PSS) may be within symbol 2 of a particular subframe of a frame. PSS is used by UEs (e.g., 104 of fig. 1 and 2) to determine subframe/symbol timing and physical layer identity.

The Secondary Synchronization Signal (SSS) may be within symbol 4 of a particular subframe of a frame. SSS is used by the UE to determine the physical layer cell identity group number and radio frame timing.

Based on the physical layer identity and the physical layer cell identity group number, the UE may determine a Physical Cell Identifier (PCI). Based on the PCI, the UE can determine the location of the aforementioned DM-RS. A Physical Broadcast Channel (PBCH) carrying a Master Information Block (MIB) may be logically grouped with PSS and SSS to form a Synchronization Signal (SS)/PBCH block. The MIB provides the number of RBs in the system bandwidth, and a System Frame Number (SFN). The Physical Downlink Shared Channel (PDSCH) carries user data, broadcast system information such as System Information Blocks (SIBs) not transmitted over the PBCH, and paging messages.

As illustrated in fig. 3C, some REs carry DM-RS for channel estimation at the base station (indicated as R for one particular configuration, but other DM-RS configurations are possible). The UE may transmit DM-RS for a Physical Uplink Control Channel (PUCCH) and DM-RS for a Physical Uplink Shared Channel (PUSCH). The PUSCH DM-RS may be transmitted in the previous or the previous two symbols of the PUSCH. The PUCCH DM-RS may be transmitted in different configurations depending on whether the short PUCCH or the long PUCCH is transmitted and depending on the specific PUCCH format used. The UE may transmit Sounding Reference Signals (SRS). The SRS may be transmitted in the last symbol of the subframe. The SRS may have a comb structure, and the UE may transmit the SRS on one of the comb. The SRS may be used by the base station for channel quality estimation to enable frequency-dependent scheduling on the UL.

Fig. 3D illustrates examples of various UL channels within a subframe of a frame. The PUCCH may be located as indicated in one configuration. The PUCCH carries Uplink Control Information (UCI) such as a scheduling request, a Channel Quality Indicator (CQI), a Precoding Matrix Indicator (PMI), a Rank Indicator (RI), and HARQ ACK/NACK feedback. PUSCH carries data and may additionally be used to carry Buffer Status Reports (BSR), power Headroom Reports (PHR), and/or UCI.

Additional considerations

The preceding description provides examples of variable Tracking Reference Signal (TRS) densities in a communication system. The previous description is provided to enable any person skilled in the art to practice the various aspects described herein. The examples discussed herein are not limiting of the scope, applicability, or aspects set forth in the claims. Various modifications to these aspects will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other aspects. For example, changes may be made in the function and arrangement of elements discussed without departing from the scope of the disclosure. Various examples may omit, substitute, or add various procedures or components as appropriate. For example, the described methods may be performed in a different order than described, and various steps may be added, omitted, or combined. Moreover, features described with reference to some examples may be combined in some other examples. For example, an apparatus may be implemented or a method practiced using any number of the aspects set forth herein. In addition, the scope of the present disclosure is intended to cover such an apparatus or method practiced using other structure, functionality, or both, that is complementary to, or different from, the various aspects of the present disclosure set forth herein. It should be understood that any aspect of the disclosure disclosed herein may be embodied by one or more elements of the claims.

The techniques described herein may be used for various wireless communication techniques such as 5G (e.g., 5G NR), 3GPP Long Term Evolution (LTE), LTE-advanced (LTE-a), code Division Multiple Access (CDMA), time Division Multiple Access (TDMA), frequency Division Multiple Access (FDMA), orthogonal Frequency Division Multiple Access (OFDMA), single carrier frequency division multiple access (SC-FDMA), time division synchronous code division multiple access (TD-SCDMA), and other networks. The terms "network" and "system" are often used interchangeably. CDMA networks may implement technologies such as Universal Terrestrial Radio Access (UTRA), CDMA2000, and other radios. UTRA includes Wideband CDMA (WCDMA) and other variations of CDMA. cdma2000 covers IS-2000, IS-95, and IS-856 standards. TDMA networks may implement radio technologies such as global system for mobile communications (GSM). OFDMA networks may implement technologies such as NR (e.g., 5G RA), evolved UTRA (E-UTRA), ultra Mobile Broadband (UMB), IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, flash-OFDMA, and other radio technologies. UTRA and E-UTRA are parts of Universal Mobile Telecommunications System (UMTS). LTE and LTE-a are versions of UMTS that use E-UTRA. UTRA, E-UTRA, UMTS, LTE, LTE-a and GSM are described in the literature from an organization named "third generation partnership project" (3 GPP). cdma2000 and UMB are described in literature from an organization named "third generation partnership project 2" (3 GPP 2). NR is an emerging wireless communication technology under development.

The various illustrative logical blocks, modules, and circuits described in connection with the disclosure herein may be implemented or performed with a general purpose processor, a Digital Signal Processor (DSP), an ASIC, a Field Programmable Gate Array (FPGA) or other Programmable Logic Device (PLD), 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 in the alternative, the processor may be any commercially available processor, controller, microcontroller, or state machine. A 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, one or more microprocessors in conjunction with a DSP core, a system-on-a-chip (SoC), or any other such configuration.

If implemented in hardware, an example hardware configuration may include a processing system in a wireless node. The processing system may be implemented with a bus architecture. The bus may include any number of interconnecting buses and bridges depending on the specific application of the processing system and the overall design constraints. The bus may link together various circuits including processors, machine-readable media, and bus interfaces. A bus interface may be used to connect network adapters and the like to the processing system via the bus. The network adapter may be used to implement the signal processing functions of the PHY layer. In the case of user equipment (see fig. 1), user interfaces (e.g., keypad, display, mouse, joystick, touch screen, biometric sensor, proximity sensor, light emitting element, and others) may also be connected to the bus. The bus may also link various other circuits such as timing sources, peripherals, voltage regulators, power management circuits, and the like, which are well known in the art, and therefore, will not be described any further. A processor may be implemented with one or more general-purpose and/or special-purpose processors. Examples include microprocessors, microcontrollers, DSP processors, and other circuitry capable of executing software. Those skilled in the art will recognize how to optimally implement the functionality described with respect to the processing system, depending upon the particular application and overall design constraints imposed on the overall system.

If implemented in software, the functions may be stored on or transmitted over as one or more instructions or code on a computer-readable medium. Software should be construed broadly to mean instructions, data, or any combination thereof, whether referred to as software, firmware, middleware, microcode, hardware description language, or otherwise. Computer-readable media includes both computer storage media and communication media including any medium that facilitates transfer of a computer program from one place to another. The processor may be responsible for managing the bus and general processing, including the execution of software modules stored on a machine-readable storage medium. A computer readable storage medium may be coupled to a processor such that the processor can read information from, and write information to, the storage medium. In the alternative, the storage medium may be integral to the processor. By way of example, machine-readable media may comprise a transmission line, a carrier wave modulated by data, and/or a computer-readable storage medium having instructions stored thereon, separate from the wireless node, all of which may be accessed by a processor through a bus interface. Alternatively or additionally, the machine-readable medium, or any portion thereof, may be integrated into the processor, such as the cache and/or general purpose register file, as may be the case. By way of example, a machine-readable storage medium may comprise RAM (random access memory), flash memory, ROM (read only memory), PROM (programmable read only memory), EPROM (erasable programmable read only memory), EEPROM (electrically erasable programmable read only memory), registers, a magnetic disk, an optical disk, a hard drive, or any other suitable storage medium, or any combination thereof. The machine-readable medium may be implemented in a computer program product.

A software module may comprise a single instruction, or many instructions, and may be distributed over several different code segments, among different programs, and across multiple storage media. The computer readable medium may include a plurality of software modules. These software modules include instructions that, when executed by equipment (such as a processor), cause a processing system to perform various functions. These software modules may include a transmit module and a receive module. Each software module may reside in a single storage device or be distributed across multiple storage devices. As an example, when a trigger event occurs, the software module may be loaded into RAM from a hard drive. During execution of the software module, the processor may load some instructions into the cache to increase access speed. One or more cache lines may then be loaded into a general purpose register file for execution by the processor. Where functionality of a software module is described below, it will be understood that such functionality is implemented by a processor when executing instructions from the software module.

As used herein, the term "exemplary" means "serving as an example, instance, or illustration. Any aspect described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other aspects.

As used herein, a phrase referring to a list of items "at least one of" refers to any combination of these items, including individual members. As an example, "at least one of a, b, or c" is intended to encompass: a. b, c, a-b, a-c, b-c, and a-b-c, as well as any combination having multiple identical elements (e.g., a-a-a, a-a-b, a-a-c, a-b-b, a-c-c, b-b-b, b-b-c, c-c, and c-c-c, or any other ordering of a, b, and c).

As used herein, the term "determining" encompasses a wide variety of actions. For example, "determining" may include calculating, computing, processing, deriving, researching, looking up (e.g., looking up in a table, database, or another data structure), ascertaining, and the like. Also, "determining" may include receiving (e.g., receiving information), accessing (e.g., accessing data in memory), and the like. Also, "determining" may include parsing, selecting, choosing, establishing, and the like.

The methods disclosed herein comprise one or more steps or actions for achieving the method. These method steps and/or actions may be interchanged with one another without departing from the scope of the claims. In other words, unless a specific order of steps or actions is specified, the order and/or use of specific steps and/or actions may be modified without departing from the scope of the claims. Furthermore, the various operations of the above-described methods may be performed by any suitable means capable of performing the corresponding functions. These means may comprise various hardware and/or software components and/or modules including, but not limited to, circuits, application Specific Integrated Circuits (ASICs), or processors. Generally, where there are operations illustrated in the figures, these operations may have corresponding counterpart means-plus-function components with similar numbers.

The following claims are not intended to be limited to the aspects shown herein but are to be accorded the full scope consistent with the language of the claims. Within the claims, reference to an element in the singular is not intended to mean "one and only one" (unless specifically so stated) but rather "one or more". The term "some" means one or more unless specifically stated otherwise. No element of a claim should be construed under the specification of 35u.s.c. ≡112 (f) unless the element is explicitly recited using the phrase "means for … …" or in the case of method claims the element is recited using the phrase "step for … …". The elements of the various aspects described throughout this disclosure are all structural and functional equivalents that are presently or later to be known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the claims. Furthermore, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the claims.

Claims (30)

1. An apparatus for wireless communication at a User Equipment (UE), comprising:

A memory;

a transceiver; and

one or more processors coupled to the memory and the transceiver, the one or more processors configured to cause the UE to:

monitoring a wideband Reference Signal (RS) from a network entity when one or more conditions are met, the wideband RS occupying a frequency resource that is wider than a Tracking Reference Signal (TRS) transmitted by the network entity; and

at least one of frequency tracking or timing tracking is performed based on the monitoring.

2. The apparatus of claim 1, wherein the wideband RS comprises a wideband demodulation reference signal (DMRS) transmitted from the network entity using a wideband precoder.

3. The apparatus of claim 2, wherein the one or more conditions comprise a Radio Resource Control (RRC) configuration of the TRS that the UE has not received.

4. The device of claim 3, wherein the one or more conditions further comprise at least one of:

the Synchronization Signal Block (SSB) subcarrier spacing (SCS) is smaller than the Physical Downlink Shared Channel (PDSCH) SCS; or alternatively

The UE receives System Information (SI) indicating that the UE is to use the wideband DMRS to perform at least one of frequency tracking or timing tracking for an upcoming transmission.

5. The apparatus of claim 3, wherein the one or more processors are further configured to cause the UE to:

receiving, via the transceiver, an RRC configuration indicating the wideband precoder;

receiving, via the transceiver, a Downlink Control Information (DCI) message scheduling a subsequent transmission; and

the subsequent transmission is received via the transceiver, wherein the subsequent transmission is transmitted by the network with the wideband DMRS using the wideband precoder.

6. The apparatus of claim 2, wherein at least one of the conditions is that the UE has provided an indication that the UE supports Timing Offset Compensation (TOC) using the wideband DMRS.

7. The apparatus of claim 6, wherein the one or more processors are further configured to cause the UE to receive, via the transceiver, signaling to the UE to perform time refinement based on the wideband DMRS as an alternative or in addition to the TRS after receiving a Radio Resource Control (RRC) configuration.

8. The apparatus of claim 2, wherein the one or more processors are further configured to cause the UE to:

receiving, via the transceiver, a Downlink Control Information (DCI) message indicating at least two Transmission Configuration Indicator (TCI) states; and

Different bundling sizes are applied for transmissions using the at least two TCI states.

9. The apparatus of claim 8, wherein applying different bundling sizes for transmissions using the at least two TCI states comprises:

applying a first bundling size indicated in the DCI for a transmission using a first TCI state; and

applying a second bundle size to transmissions using a second TCI state, wherein the second bundle size is: indicated via at least one of Radio Resource Control (RRC) or Medium Access Control (MAC) Control Element (CE) signaling derived from TRS transmissions or indicated in the DCI.

10. The apparatus of claim 8, wherein the different bundling sizes are configured for the at least two TCI states.

11. The apparatus of claim 8, wherein the different bundling sizes are determined based on a field in the DCI mapped to a bundling size vector for the at least two TCI states.

12. The apparatus of claim 2, wherein the one or more processors are further configured to cause the UE to:

monitoring the TRS with one or more beams quasi co-located (QCL) with one or more beams used to monitor the wideband DMRS; and

The wideband DMRS and the TRS are jointly processed to perform at least one of frequency tracking or timing tracking.

13. The apparatus of claim 12, wherein the joint processing is performed to refine a frequency offset estimate.

14. The apparatus of claim 12, wherein the one or more processors are further configured to cause the UE to receive, via the transceiver, an indication of whether the same precoder is used for the wideband DMRS and the TRS, wherein the indication is received via at least one of Radio Resource Control (RRC), medium Access Control (MAC) Control Element (CE), or Downlink Control Information (DCI) signaling.

15. An apparatus for wireless communication by a network entity, comprising:

a memory; and

one or more processors configured to cause the network entity to:

detecting when one or more conditions are met to trigger transmission of a wideband Reference Signal (RS) that occupies a frequency resource that is wider than a Tracking Reference Signal (TRS) transmitted by the network entity; and

the wideband RS is transmitted based on the detection.

16. The apparatus of claim 15, wherein the wideband RS comprises a wideband demodulation reference signal (DMRS) transmitted from the network entity using a wideband precoder.

17. The apparatus of claim 16, wherein the one or more conditions comprise a Radio Resource Control (RRC) configuration of the TRS that has not been received by a User Equipment (UE).

18. The device of claim 17, wherein the one or more conditions further comprise at least one of:

the Synchronization Signal Block (SSB) subcarrier spacing (SCS) is smaller than the Physical Downlink Shared Channel (PDSCH) SCS; or alternatively

The UE receives System Information (SI) indicating that the UE is to use the wideband DMRS to perform at least one of frequency tracking or timing tracking for an upcoming transmission.

19. The apparatus of claim 17, wherein the one or more processors are further configured to cause the network entity to:

transmitting an RRC configuration indicating the wideband precoder;

transmitting a Downlink Control Information (DCI) message scheduling a subsequent transmission; and

the subsequent transmission is transmitted with the wideband DMRS using the wideband precoder.

20. The apparatus of claim 16, wherein at least one of the conditions is that the UE has provided an indication that the UE supports Timing Offset Compensation (TOC) using the wideband DMRS.

21. The apparatus of claim 20, wherein the network entity is to:

a first set of one or more User Equipments (UEs) indicating support for TOC using the wideband DMRS are configured to have fewer TRS transmissions than are configured for a second set of one or more UEs.

22. The apparatus of claim 20, wherein the one or more processors are further configured to cause the network entity to transmit signaling to the UE to perform time refinement based on the wideband DMRS as an alternative or in addition to the TRS after transmitting a Radio Resource Control (RRC) configuration.

23. The apparatus of claim 16, wherein the one or more processors are further configured to cause the network entity to:

a Downlink Control Information (DCI) message is transmitted indicating at least two Transmission Configuration Indicator (TCI) states associated with different bundling sizes for application by the UE to a bundled transmission.

24. The apparatus of claim 23, wherein the different bundling sizes comprise:

a first bundling size indicated in the DCI for a transmission using a first TCI state; and

a second bundle size for transmissions using a second TCI state, wherein the second bundle size is: indicated via at least one of Radio Resource Control (RRC) or Medium Access Control (MAC) Control Element (CE) signaling derived from TRS transmissions or indicated in the DCI.

25. The apparatus of claim 16, wherein the one or more processors are further configured to cause the network entity to:

transmitting a TRS, wherein the network entity transmits the DMRS and the TRS with quasi-co-located (QCL) beams.

26. The apparatus of claim 25, wherein the one or more processors are further configured to cause the network entity to transmit an indication of whether the same precoder is used for the wideband DMRS and the TRS, wherein the indication is transmitted via at least one of Radio Resource Control (RRC), medium Access Control (MAC) Control Element (CE), or Downlink Control Information (DCI) signaling.

27. A method for wireless communication by a User Equipment (UE), comprising:

monitoring a wideband Reference Signal (RS) from a network entity when one or more conditions are met, the wideband RS occupying a frequency resource that is wider than a Tracking Reference Signal (TRS) transmitted by the network entity; and

at least one of frequency tracking or timing tracking is performed based on the monitoring.

28. The method of claim 27, wherein the wideband RS comprises a wideband demodulation reference signal (DMRS) transmitted from the network entity using a wideband precoder.

29. The method of claim 27, wherein the one or more conditions comprise a Radio Resource Control (RRC) configuration of the TRS that the UE has not received.

30. A method for wireless communication by a network entity, comprising:

detecting when one or more conditions are met to trigger transmission of a wideband Reference Signal (RS) that occupies a frequency resource that is wider than a Tracking Reference Signal (TRS) transmitted by the network entity; and

the wideband RS is transmitted based on the detection.